diatmll Mmmvsit^ Kibrarg Stlfata, Hern ^atk THE LIBRARY OF EMIL KUICHLING. C. E. ROCHESTER. NEW YORK THE GIFT OF SARAH L. KUICHLtNG 1919 Cornell University Library TD 525.C5A5 1914 V.1 Report on Industrial wastes *fO'" {J'lf. **° 3 1924 005 001 312 en,,,, Cornell University Library The original of tiiis book is in tine Cornell University Library. There are no known copyright restrictions in the United States on the use of the text. http://www.archive.org/details/cu31924005001312 REPORT ON Industrial Wastes FROM THE Stock Yards and Packingtown IN CHICAGO MADE TO THE BOARD OF TRUSTEES OF THE SANITARY DISTRICt'oF CHICAGO OCTOBER, 1914. K'^^/^ 172 IT. I^aSaiiI^b] Sx., Gbioaso 137 BOARD OF TRUSTEES 1913-1914 Feed D. Beeit Wallace G. Clabk James M. Dailet Paul A. Hazard Edwaed Kane George W. Paullin Charles E. Reading Thomas M. Sullivan Thomas A. Smyth OFFICERS Thomas A. Smyth President George M. Wisner Chief Engineer John A. McCormick (Vice Pres. Chicago Savings Bank & Trust Co.) Treasurer John McGillen Clerk Edmund D. Adcock Attorney ENGINEERING COMMITTEE Thomas M. Sullivan; Chairman Fred D. Breit Paul A. Hazard James M. Dailey Edwaed Kane offices karpen building CHICAGO TABLE OF CONTENTS PAGE Letter of Transmittal i-iv Summary of Investigations and Recommendations iv-xxii Chapter I. The Stockyards and Packingtown Industry .... 1-19 II. Examination of Individual Houses 19-25 III. The Stockyards 25-31 IV. Description of Center Ave. Testing Station. . . .31-40 V. Crude Sewage, Center Ave 40-53 VI. Grit Chamber 53-50 VII. Plain Sedimentation in Dortmund Tanks 58-76 VIII. Plain Sedimentation in the Emscher Tank 76-93 IX. Chemical Precipitation 93-110 X. Sludge Treatment 110-133 XI. Screening 133-163 'XII. Comparison of Methods of Preliminary Treat- ment 163-174 XIII. Sprinkling Filter 174-187 XIV. Fat Treatment 187-195 XV. Oxygen Requirements 195-200 XVI. Existing sewers 200-211 XVII. Projects 211-223 Appendix I. List of Firms in Stockyards and Packing- town" 223-225 II. Test at Packinghouse of Adler & Oberndorf. 225-227 III. Test at Packinghouse of Anglo-American Pro- vision Co 227-232 IV. Test at Packinghouse of Armour & Co. 232-239 V. Test at Armour Glue Works 239-242 VI. Test at Packinghouse of Boyd-Lunham Co. . . 242-245 VII. Test at Packinghouse of Brennaq Packing Co 245-247 VIII. Test at Packinghouse of Chicago Packing Co 247-250 PAGE IX. Test at Glue Plant of Darling Fertilizer Co 250-252 X. Test at Packinghouse of Friedman M'f'g Co 252-254 XI. Test at Packinghouse of Henry Guth 254-256 XII. Test at Packinghouse of G. H. Hammond Co 256-266 XIII. Test at Packinghouse of Independent Packing Co , 266-269 XIV. Test at Packinghouse of Libby, McNeill & Libby 269-272 XV. Test at Packinghouse of Miller & Hart 272-275 XVI. Test at Packinghouse of Morris & Co 275-285 XVII. Test at Packinghouse of Northwestern Glue Co 285-287 XVIII. Test at Packinghouse of Peoples Packing Co 287-289 XIX. Test at Packinghouse of Louis Pfaelzer & Sons , 289-292 XX. Test at Packinghouse of Siegel-Hechinger . . 292-294 XXI. Test at Packinghouse of Standard Slaughter- ing Co. '. .-. .294-296 XXII. Test at Packinghouse of Sulzberger & Sons . 296-303 XXIII. Test at Packinghouse of Swift & Co 303-315 XXIV. Test j,t Packinghouse of Western Packing Co. 315-318 XXV. Methods of Sampling and Analysis 318-321 List of Tables, Diagrams, and Plates and General Index. . . .321-346 REPORT ON INDUSTRIAL WASTES FROM THE Stockyards and Packingtown IN CHICAGO Made to the Engineering Committee of the Sanitary District of Chicago ' GEORGE M. WISNER, Chief Engineer LANGDON PEARSE, Division Engineer LETTER OF TRANSMITTAL / Chicago, October 15, 1914. To the Honorable, the Committee on Engineering. Gentlemen : For the past three years this Department has been making a careful study of the sewage and sewerage conditions of the region known as the Stockyards and Packingtown, which drains into the East and West Arms of the South Pork of the South Branch of the Chicago River. For the past two years a sewage testing station has been operated at the outlet of the Center Ave. sewer into which comes much of the sewage from the packing plants. The construc- tion cost of this testing station was largely defrayed by a fund con- tributed by the various firms in Packingtown, the Union Stockyards and Transit Co. furnishing the land at a nominal rental. In con- sideration of this contribution a report was promised to the sub- scribers, which I now have the honor; to present, The report and estimates are, necessarily preliminary. Before any actual construction work can be done, a detailed survey of the district and its sewers will be required and detailed plans prepared for treatment works. The legal phases of the situation require con- 11 sideration and the determination of who shall finance the work is all important. The report indicates methods of treatment which have been demonstrated, and points out the feasibility of handling the wastes from the entire packing and stockyards industry, so that eventually no load of that character would be put upon the main channel of the Sanitary District, if circumstances require. The investigation clearly shows that the sewers now existing in the Stockyards and Packingtown are inadequate and need re- building. In view of the f acfr that the City of Chicago is proposing to construct a new sewer along Center Ave., the time is ripe to adopt a definite plan for a sewerage system and for sewage treatment of the industrial wastes of this section. Our feeling has been that a community plant is desirable be- cause of the concentration of the operation in one locality and con- sequent ease of securing the best and most economical operation. On the other hand, there is force in the argument that each firm would prefer to control its own waste. Yet some firms now operate recovery plants for grease on community sewers. Our conclusion is that fine screening is entirely feasible and advisable at each indi- vidual house or group of houses belonging to a firm, in addition to and following grease skimming. Screening should be supplemerited by a sedimentation plant either at each house or preferably in a community plant. The report covers many phases of the Stockyards and Packing industry and represents the combined work of the Sanitary Divi- sion, under the direction of Mr. Langdon Pearse, Division Engineer. To Dr. Arthur Lederer, Chemist, for investigation in the chemical and bio-chemical fields, and to Mr. L. C. Whittemore, Eesident Engi- neer, for field supervision, compilation of the records and prepara- tion of the report, due acknowledgment is made, as well as to the other assistants in both engineering and laboratory work who have carried out the work. To the officials of the Union Stockyards and Transit Co., as well as of the packing houses, ^11 of which firms are listed in Appendix I, thanks are due for hearty co-operation and assistance in carrying through the investigation. In view of the injunction suit now pending in the Federal courts to determine our right to take diluting water from Lake Michigan over and above 4167 cu. ft. per sec. and the need of adjusting all improvements to the outcome of that case, I feel that the Board of Trustees should carefully consider this report and consult with the representatives of the interested industries, as well as the oflficials Ill of the City of Chicago, in order to agree upon a workable plan. The organic law of The Sanitary District of Chicago is based on the theory that a channel will be constructed solely for the recep- tion of domestic wastes. The Federal statutes distinctly prohibit the dumping or discharge of settling solids into any navigable water or tributary thereof. Under these authorities, it would be possible to close up absolutely every industrial establishment discharging wastes into the Chicago Eiver or Drainage Canal. Undoubtedly, the law intends that the larger burden shall be carried by the industries. Improvement of existing conditions is imperative. In the present stress of finance and industries, time should be given to all con- cerned to look the situation squarely in the face and to decide what they will do. Certain improvements can now be made at moderate expens.e. Greater expenditures for further improvement can be met later. For many years Bubbly Creek has been a byword, but I hope soon with the co-operation of all concerned that it will become a memory. EespectfuUy submitted, GEORGE M. WISNER, Chief Engineer. REPORT ON INDUSTRIAL WASTES FROM "raE Stockyards and Packingtown IN CHICAGO The Industry, Its Units and Its Wastes; Tests of Treatment, and a Project for the Improvement of Bubbly Creek ' For Details, see Chapters I to XVII following SUMMARY. GENEEAL. Some two years ago, negotiations were begun with the firms in the Stockyards and Packingtown by which a testing station was put in operation at Center Ave. in September, 1912. Engineering studies were made on various alternatives for. sewers in handling industrial wastes. It was early recognized that in such development some heed should be paid to the possible future re- quirements both for sewerage and sewage disposal, as the U. S. gov- ernment has been seeking to enjoin the Sanitary District from di- verting more than 4167 cubic feet per second from Lake Michigan. This suit is not yet decided. Last year a movement was started to fill up Bubbly Creek, that is the west arm of the south fork of the south branch of the Chicago Eiver. This would reclaim a certain amount of space, now useless, and would permanently remove from the vicinity of Packingtown the present river nuisance. Unless steps were taken, however, to reduce the organic load, this removal in itself would only transfer the present trouble to other localities. WESTERN AVE. CONDUIT. In 1909 a conduit was built from the west end of the west arm of Bubbly Creek north to and along "West 39th St. to Western Ave. and thence north to the Drainage Canal at 31st St. This conduit was expected to cause a circulation in the then stagnant west arm, by utilizing a slight difference of head. But continued use for over four years has not proven this adequate. Material settles in the west arm as markedly as before. A recent inspection of the conduit has shown deposits from two to four feet deep, due to low velocities, and a much reduced flow, at present about 75 cubic feet per second, practically the flow of "West- ern Ave. and Eobey St. sewers plus Ashland Ave. In the present c6ndition of the conduit, this flow appears largely independent of the working of the flushing pumps at 39th St. and Lake Michigan. DREDGING. Dredging was carried out last year at a total ex- pense of $34,534.05, of which the committee of packers ahd the stock- yards paid $26,864.38. This affords, however, only temporary relief, since the dredged spots fill in again and all the while the deposits on the bottom become septic, blow up, form scum and give the dis- agreeable appearance from which the characteristic name, "Bubbly Creek, ' ' was derived. TESTING STATION. The testing station investigations at Cen- ter Ave. have been extended beyond the original program, because certain additional experiments were found necessary to study the treatment of settled sewage on sprinkling filters and the behavior of devices under a longer trial than one year. Other special tests on sludge handling, recovery of fats and the like are still under way. The formulation of a new method of testing effluents early in 1914, by our Chemist, Dr. Lederer, also emphasized the need of learning at some length the comparative oxygen requirements of domestic sewage, as well as Packingtown wastes and other industrial sewage. The original testing station layout (1912) was equipped with a coarse screen with f in. clear openings, a 2 in. centrifugal pump, a grit chamber, Emscher tank and Dortmund tank. To this has been added a fine mesh (30 meshes to the inch) rotary screen of the Weand type, a sprinkling filter and a chemical precipitation tank with devices for mixing and applying chemicals. A screen testing device was also added, as well as sedimentation cans. CRUDE SEWAGE. The sewage at both Center Ave. and Ash- land Ave. outlets is very strong, containing large amounts of both suspended and soluble matter (cf. table 116). At different hours of the day, the crude sewage varies greatly in strength according to the discharge of wastes from the stockyards and Packingtown. The average analyses for the year 1913 for the day and night flow from Center Ave. sewer are given in table 9. The character of the night flow and Sunday flow was practically identical. Some seasonal vari- ation in strength occurred, the sewage being weakest during the spring and summer and attaining a maximum strength during the late fall and early winter. The great strength of the day sewage is clearly shown by comparison with the -purely domestic sewage from 39th St. sewage pumping station (cf. table 116). At Center Ave. a biologic oxygen consumption of roughly 1000 p. p. m. was VI found for the crude day sewage, whereas at 39th St. this was only 100 to 150 p. p. m. The temperature of the sewage at Center Ave. ranged from 60 deg. Pahr. in the winter to 90 deg. Pahr. in the summer, being nearly 20 deg. warmer than the domestic sewage at 39th St. (of. fig. 11). The average week day flow at Center Ave. sewer, gaged during 11 months in 1912-13, varied from 16.4 cu. ft. per sec. at night to 29.0 cu. ft. per sec. by day (cf. fig. 19), with a maximum recorded hourly rate of 105 cu. ft. per sec. during a rainstorm. The Sunday flow has averaged 14.1 cu. ft. per sec. Of this flow about 150,000 gal. per 24 hr. have been handled in the testing station. SCREENING, COARSE. All the crude sewage used in the testing station passed through a bar screen with | in. clear openings. The retention of solid material was nominal, averaging about 90 lb. of moist screenings per mil. gal. with a moisture content of 82 per cent. The screenings are largely hair, coarse vegetable matter, guts and similar material quite foreign to domestic sewage. A coarse screen is requisite in any case to protect pumps and other devices. GRIT CHAMBER. The grit chaimber has been operated at velocities from 17 to 25 ft. per min. With a detention period vary- ing between 50 and 70 sec, the suspended matter has decreased in- appreciably, but a slight deposit of detritus, largely mineral, has occurred in amount about 0.02 cu. yd. per mil. gal., with a specific gravity of 1.3 and a moisture content of 44 per cent. The grit cham- ber has acted largely as a grease skimmer, from 5 to 1260 lb. of scum per mil. gal. having been removed, containing on an average about 75 per cent, moisture. Of the dry residue about 60 per cent, is ether soluble. This is, however, by no means a complete fat re- covery, being less than 11 per cent, of the total fat. The collection is higher in winter than in summer. TREATMENT- IN SETTLING TANKS. Plain sedimentation was tried in both Dortmund and Emscher tanks, and chemical pre- cipitation in a Dortmund tank. The Emscher tank, at first arranged for a downward and upward flow, was changed in March, 1914, to a straight horizontal flow tank. A daily average of 49 to 69 per cent, of the suspended matter in the heavy day sewage can be removed by plain sedimentation in tanks of the Dortmund and Emscher vertical flow types with periods from 1 to 4 hours. The effectiveness of the vertical flow tanks of the Dortmund or Emscher type depends on low velocities. Prom 60 to Vll 70 per cent, of the suspended matter can be removed in straight flow Emscher tanks with a period from 2 to 3 hours. Chemical precipi- tation will remove upwards of 80 per cent, of the suspended matter, using about 3.0 grains of iron sulphate and 5 grains of lime per gallon. "^ QUIESCENT SEDIMENTATION. Special experiments on quiescent sedimentation in a deep can, along the lines indicated by Steuernagel at Cologne, Germany, show a removal of 76 per cent, of the suspended matter in 2 hr., with 1100 p. p. m. present. Ex- tended settling over 12 hr. indicates a removal of 79 per cent., which may be taken to represent the settling suspended matter. The re- sults plotted in fig. 17, indicate higher removals than for similar experiments on 39th St. sewage. DORTMUND TANKS. The Dortmund tanks have been oper- ated at varying detention periods and velocities. The average re- moval of suspended matter is as follows (see also table 27) : TJpward Per Cent Removal Average Detention Suspended Matter Number of . Velocity Ft. per Hr. Period Hours Months Averaged Tank Day 24 Hour Sewage Sewage 4.5 1.0 49 47 1 C 2.6 4.0 54 48 2 D 2.3 1.9 54 53 4 C 1.8 2.0 49 42 1 C 1.7 6.0 63 57 3 D 1.5* 3.0* 72* 67* 2* C 1.1 4.0 69 65 /3 C 1.0 10.0 80 72 1 D ' One month on raw sewage and one month on screened sewage in daytime. These results show that in a Dortmund type of tank, both velocity and detention period are factors in the efficiency of removal of suspended matter. Low velocity is more important than a long period, as the same detention period gives greater efficiencies with the lower velocities. This is of great importance in determining the economy of this type of tank. For instance, with a velocity of 1 ft. per hr., the removal is considerably higher than with velocities of 2.5 ft. and over. As the settling efficiency depends on the Velocity, and the capacity on the area multiplied by the velocity, high velocities are desirable from the viewpoint of econ- omy, but undesirable from the standpoint of efficiency. Vlll EMSCHER TANK. With the Bmscher tank, the following re- sults have been obtained (see also table 45) : Average .Upward Detention Period Hours Per Cent Removal, Suspended Maiteb Number of Months Velocity Ft. per Hr. Day Sewage 24 Hour Sewage Averaged^ ORIGINAL TANK. VERTICAL FLOW 1.9 2.5 3.8 5.0 4.0 52 45 3.0 50 47 2.0 51 48 1.5 53 50 REMODELED TANK. HORIZONTAL FLOW 2.5 2.0 5.5 4.0 9.2* 6.0* 1.9 61 58 2.9 72 69 2.3 3,0 * Horizontal Vel. Ft. per Hr. Less variation occurred for different periods and velocities than with the Dortmund tanks. The relatively high efficiency for the 1^ hr. detention period may have been influenced by the addition of scum baffles about that time, which retained considerable light floating inaterial from passing off in the effluent. The disturbances incidental to "ripening" of the sludge digestion chamber, also in- terfered with the efficiency of the tank during the first few months of operation. CHEMICAL PRECIPITATION. With chemical precipitation, using copperas or alum and lime, or alum alone, during the hours of strong flow, and plain sedimentation during the night, a reduc- tion in suspended matter of about 80 per cent, was secured. The Grains PEK Gal. Per Cent Reduction Upward Vel. Detention Suspended Matter Ft. per Hr. Period, Hr. Copperas 1 Lime Day 1 24 Hour 3.3 3.0 5.5 10,3 76 72 3.3 3.0, 4.5 10.2 80 77 3.3 3.0 3.5 9.9 84 79 2.2 2.0 3.3 8.6 78 74 2.2 2.0 3.5 5.1 67 68 2.5 4.0 3.5 5.1 79 70 2.5 4.0 2,4 5.2 82 74 2.5 4.0 5,2 5,5 72 65 1.7 6,0 4,9 6,0 77 2.6 4.0 2,4* 2.8 64 52 2.6 . 4.0 3,0* 0.0 73 • 66 2.6 4.0 1,9* 2.7 82 76 2.6 4.0 3,2* 0.0 80 76 * Alum used instead of copperas. IX following figures show the results of individual runs (see also table 55): The apparatus for mixing and applying the chemicals was some- what crude. In a large installation at least 3 gr. per gal. of copperas and 5 of lime would probably be required. Lime is essential to obtain a floe with the copperas. With alum a floe was formed with- out the addition of lime but scum formation was excessive. The cost for chemicals alone was assumed at $0.50 per mil. gal. for each grain of lime per gallon, $0.65 for each grain of copperas, and $1.15 for each grain of alum. On the basis given, 3 gr. per gal. of copperas would cost $1.95 per mil. gal. and 5 gr. per gal. of lime would cost $2.50 per mil. gal., making a' total chemical cost alone of $4.45 per mil. gal. SLUDGE ACCUMULATION. The amount of sludge retained in the various devices varied considerably per unit volume for individual measurements, apparently due to fluctuations in water content, slight changes influencing the volume very markedly. The relative proportion of bottom kludge and top scum is also a factor of importance. The following 'figures, based on actual measure- ments, indicate the amounts of sludge found in cubic yards per million gallons of sewage: Tank Cu. Yd. peh Milmon Gallons Sludge Scum Sludge and Scum Period of Observation Dortmund C. . Dortmund D . Emscher E . . . Chem. Preclp. 3.1 2.7 5.8 June 24, 1913, to June 19, 1914 6.1 3.5, 9.6 Sept. 16, 1912, to July 7,1913 6.8 1.3 8.1 Sept. 16, 1912, to June 1,1914 12.7 ... 12.7 Aug. 28, 1913, to June 1,1914 The figure for chemical precipitation is the average of individ- ual runs, using copperas and lime, the others are cumulative aver- ages over long periods. With alum instead of copperas, consider- able scum formed, but those results are not included in the table. The scum accumulation in the Emscher tank is high because of the inclusion of the scum removed during the ripening period. At that time it formed in large amounts, but afterwards very much less accumulated. These figures were obtained with a uniform rate of flow through the tanks throughout the entire 24 hours. But as the day flow in the sewer is much greater than the average flow during the hours of flow iwhen the sewage is strongest and consequently when deposition is greatest, in adapting these figures to actual de- sign, operating conditions must be taken into account. For uniform flow the figures are correct, but for a variable flow through a given number of units allowance must be made for the greater proportion of day flow, in figuring the probable rate of sludge accumulation. On the other hand, the greater depth of the tanks in an actual plant would have a tendency to compact the sludge and thus diminish its volume. The following table gives approximately the average composi- tion of sludges and scum from the various tanks : Percentage ON Det Basis Tank Specific Per Cent Gravity Moisture Nitro- Volatile Fixed Ether gen Matter Matter Soluble SLtJDGE Dortmund C. 1.02 90.8 2.65 72 28 8.1 Dortmund D 1.02 91.7 2.88 76 24 8.6 Emscher 1.02 91.4 2.75 64 36 6.6 Chem. Precip 1.03 89.5 2.21 - SCUM 58 42 5.1 Dortmund C 1.02 84.1 2.55 71 29 7.7 Dortmund D 1.02 84.5 2.60 75 25 9.2 Emscher 1.01 84.1 2.73 72 28 • 12.9 The digestion in the Emscher tank is shown by the decrease in the proportion of volatile matter over the fresh Dortmund sludges. The influence of the precipitant on the chemical precipitation sludge is indicated by the high ratio of fixed matter. The scums are very similar to the sludges from the respective tanks, except that the moisture content is lower. The Emscher scum, however, shows an appreciably higher percentage of volatile matter, indicating that little or no digestion has occurred. SCUM. Scum consistently persisted on the surface of the Dort- mund tanks at all times. Practically none formed on the chemical precipitation tank, except when alum was used instead of copperas. For the first seven months of operation, scum formation was ex- cessive on the Emscher tank. With the establishment of thorough ripening, however, the production of scum has shown a marked de- crease, particularly during the summer months. Experiments on Tank C using the effluent from the rotary screen seemed to indicate that scum formation could be largely eliminated by preliminary fine screening through 30 mesh screens. ODOR. Slight odor developed from the Emscher tank. A trace of hydrogen sulphide was occasionally noted, particularly when sludge was being removed. With the other tanks, the odor has been more marked, particularly during removal of sludge. XI SCEEBNING, FINE. A number of experiments were conducted on the efficiency of fine mesh screens of mesh from 4 to 40 per lineal inch. In most cases the flow was 14,800 gal. per 24 hr. per sq. ft. of screen area, on a screen approximately 3.5 sq. ft. in area, on strong day sewage running to a final loss of head of 4.5 ft. Prom 134 to 1534 Ib.^of dry material was removed per mil. gal. (table 86), with a calculated per cent, reduction of suspended matter ranging from 10 to 26 per cent. The removal by the 24, 30 and 40 mesh screens averaged from 1098 to 1534 lb. of dry material per mil. gal. 60, 80 and 100 mesh screens tested subsequently gave somewhat higher per cent, removals of suspended matter, but as the sewage at that time was weaker the pounds of dry material removed per mil. gal. was less than for the former screens previously tested (cf. tables 85, 86)'. These results indicate in general an increasing efficiency with decreasing size of mesh, under similar conditions. REMOVAL BY FINE MESH SCREENS. No. Meshes per Lineal Inch Net Length of Opening ■ Inches Dry Screenings Lb. per Mil. Gal. Suspended Matter Per Cent Ee iuction No. of Tests 4 0.198 134 3 6 0.137 654 13 5 10 0.072 421 10 6 16 0.042 992 17 4 20 0.036 919 16 4 24 0.029 1113 21 5 30 0.022 1098 19 10 40 0.015 1534 26 11 EOTARY SCREEN. Extended experiments were also made with a small rotary screen of the Weand type 2 ft. 4 in. in diameter and 4 ft. 8 in. long, swung on a steel axle. The coarse supporting screen was covered with a fine screen of 30 meshes per lineal in. The screen rotated 7 r. p. m. and was cleaned by a spray of water directed against the outside, the screenings being ejected at one end by a worm and buckets. During three separate runs, in October, No- Date Hrs. of Operation Dry Scbbbnings Lb. per Mil. Gal. Per Cent Reduction Suspended Matter Computed Max. Min. Avg. Max. Min. Avg. Oct.-Dec, 1913 May, 1914 May, 1914 July, 1914 8:00 a.m. to 4:00 p.m. 7:30 a.m. to 10:30 p.m. 10:30 p.m. to 7:30 a.m. 8:00 a.m. to 11:00 p.m. 1420 816 41 488 505 304 26 194 950 500 32 310 23 16 12 6 6 17 12 9 Xll vember and December, 1913, May, 1914, and June, 1914, each of about one month's duration, the foregoing results were obtained. Based on the actual analyses, the average reduction of sus- pended matter for the first run was about 32 per cent., as compared with the average of 17 per cent., computed by the addition of the weight of screenings to the effluent. The result of operation dur- ing the heaviest hours of the day is strikingly shown. Extending the period of operation into the evening cuts down the unit rate of accumulation, while the removal at night is comparatively low. The capacity of the screen was not found to be exceeded with rates of flow between 5300 and 8000 gal. per day per sq. ft. of net effective area, at the linear peripheral velocity of 51 ft. per min. SCREENINGS. The material caught by the screen ' differs widely in appearance from the tank sludges and scums, and is usually of a dirty greenish yellow color, firm enough as ejected to be forked after slight draining. The material is largely organic, the volatile matter in the dried residue running uniformly over 90 per cent. "When delivered from the screen, the moisture content averages between 85 and 88 per cent., but after slight draining is readily reduced to about 80 per cent. SCREENS ON STOCKYARDS AND PACKING HOUSE. Be- side the work at the testing station, additional tests were made on a traveling band screen designed by Mr. C. A. Jennings, located at the outlet of the Morgan street sewer, and also on a Weand screen, purchased by the packers, and installed at the Sulzberger plant. The Morgan street sewer receives drainage from a portion of the stockyards only. The sewage is considerably weaker than the ordinary packing wastes (ef. table 116). The Sulzberger screen was set up at the outlet for the entire plant. Both these screens were covered with wire cloth with 40 meshes per lineal in. when tested. The duration of each test at Sulzberger's was from 1 to 7 hr. (cf. table 82), according to circumstances, and from 5 to 6 hr. at Morgan St. The results of these tests are tabulated below: Sewer Outlet Dry Scrbbninos Lb. per Mil. Gal. Max. Min. Aver. Per Cent Reduction Suspended Matter Max. I Min. I Aver. No. of Tests Screen Morgan St. . . 1420 Sulzberger . . 2820 945 320 1150 1690 49 39 22 33 26 5 Jennings 7 Weand The initial content of suspended matter delivered to the Jen- nings screen averaged 340 p. p. m., whereas that at the Sulzberger XIU plant averaged 747 p. p. m. Considerably higher efficiencies are probably possible at the individual plants than can be obtained at the Center Ave. outfall, largely because of the greater concen- tration and freshness of the wastes. Although no tests were made by the District at the Armour pliant, an average efficiency of about 65 per cent, was claimed by their superintendent, Mr. Harding. This appears very high, but may be influenced by concentrated waste from certain processes, as for instance, water from the paunch ma- nure presses containing considerable coarse material in suspension. An essential requisite of a good screen is its equipment with ade- quate cleaning devices. Water was used on the screen at the testing station and compressed air on the Jennings screen. Both were effec- tive, but the high pressure at which the air was then applied resulted in rapid destruction of the wire mesh. The presence of large quan- tities of grease or fat in the sewage is likely to cause more or less clogging, by depositing or chilling in the meshes of the screen. This can be removed by occasional application of steam. At Morgan St. the 40 mesh screen removed from 4820 to 7860 lb. per mil. gal. wet material, averaging 6740 lb. or 1150 lb. dry. This removal averages about 24 per cent, actual suspended matter or a computed removal of 33 per cent. The previous summer a small straight flow tank of 1.21 hr. capacity removed 3.8 eu. yd. of sludge per mil. gal of 88.5 per cent, moisture. The removal of suspended matter averaged 63.8 per cent., with an average of 548 p. p. m. in the influent. This yardage is probably low because the tank unloaded at times. The sludge had an offensive putrid odor. Based on the removal of suspended matter, the sedimentation plant is far more effective than screening. SCREENS WITH TANKS. As an adjunct to tank treatment, fine screening is likely to prove useful. The removal of light scum- forming material from the influent to the tanks is desirable in re- ducing operation difficulties and increasing the clarity of the effluent. During the months of May and July, 1914, one tank was operated on screened sewage during the daytime, and maintained almost an entire freedom from scum throughout the month. Under ordi- nary operation, a heavy scum would have formed long before the end of the month. The reduction in amount of sludge handled is also desirable under the conditions existing in the yards. Screen- ings at the rate of 500 lb. of dry material per mil. gal. would repre- sent a reduction in volume of nearly 3 cu. yd. of sludge containing 90 per cent, moisture, or about 2 cu. yd. of scum containing 85 per cent, moisture. SLUDGE HANDLING. The handling of the liquid sludge pro- XIV duced by settling tanks is one of the important factors in reaching a conclusion. The rate of accumulation of sludge from the various devices was large and the composition largely organic. When withdrawn from the tanks in bulk, the moisture content was always greater than that in situ, as the withdrawal of some of the overlying sewage appeared almost inevitable, on a small scale. This increased the volume to be handled. The sludge from the various devices differed in appearance. That from the Emscher tank was uniformly black and even grained, flowing readily, and had little or no odor. The fresh sludge from plain sedimentation was usually of a dirty greenish black color, frequently having a very offensive odor. The consistency when run from the tank was not uniform, sometimes being very thick, while at other times quite thin. The chemical precipitation sludge was usually of a dirty greenish black, or deep black color, sticky in consistency, and ordinarily had a peculiar sickish or metallic odor. The sludge from . the secondary settling basin was usually of a deep brown color, very smooth in appearance, with an odor resembling that of decayed vegetables. ' SLUDGE DRYING. Experiments on underdrained sand beds showed that the Emscher tank sludge uniformly dried to a spadeable condition in layers 1 to 1.5 ft. thick in 5 or 6 days of good weather. Under these circumstances, the moisture content was ordinarily reduced to about 75 per cent. Although the sludge was still moist it was removed from the beds without difficulty. With fresh Dort- mund sludge dried under similar conditions the drying time varied from 2 to 4 weeks with a final moisture content of about 75 per cent. The chemical precipitation sludge was even more retentive of moisture, 3 to 4 weeks usually being required. The Emscher slucige drained largely from beneath. Within 24 hr. after application, the surface became firm and cracks began to appear. With the fresh sludge, the water ordinarily flushed to the surface, making the drying largely a matter of surface evaporation. The chemical precipitation sludge was very retentive of moisture, a thin hard crust forming on the surface while the interior of the mass remained soft and sticky for long intervals. Violent septic action was sometimes noted in this sludge after application to the beds, the surface sometimes falling 6 in. on the stirring of the mass, by the liberation of entrained gases. Little has yet been done on the secondary settling basin sludge, but the indications are that it will dry very readily in thin layers. The beds used in these experiments were about 6 in. deep, con- XV sisting of graded gravel. overlaid with about 1 to 2 in. of torpedo sand. They were exposed to the sun and air. SLUDGE PRESSING. A few experiments were made with a Kelly filter press, using the chemical precipitation and fresh sludges. Sludge was pumped into the press under pressures of from 70 to 80 lb. per sq. in., which were maintained for about 15 min., the filtrate escaping through the press cloth. Irrespective of the initial moisture content, a final result of about 75 per cent, was obtained in most cases. The sludge appeared wetter than that of similar moisture content removed from the beds, being more compact. ' One objection to ""this type of apparatus was found to be the fre- quent rehandling of sludge necessary, as the cloths becaine com- pletely clogged after a thin "cake" had farmed over them. The interior of the press was left filled with liquid sludge which had to be withdrawn to allow the cloths to be cleaned. SLUDGE FUEL VALUES. Calorific tests showed various sludges to have thermal values varying from 2500 b. t. u. per lb. for dried sludges, which had been exposed to the weather for several months, to over 9000 b. t. u. per lb. for fresh sludges and screen- ings on a dry basis. The fresh material, if rapidly dried, has a calorific value comparable to that of poor coal when computed on a dry basis. A considerable portion of these heat, units must, however, be used in evaporating the moisture content. A consider- able loss of heat-producing constituents occurs, however, on pro- tracted exposure to the air. The great bulk of water which the fresh sludges contain is the chief obstacle to their incineration. FERTILIZER VALUES. The few analyses for fertilizing con- stituents made do not promise recovery of any fertilizer values worth attention from a standpoint other than possible reduction of sludge volume. SPRINKLING FILTER. The filter was 6 ft. in depth, consist- ing of 5 ft. 6 in. of li to 2 in. limestone overlying 6 in. of 2 to 4 in. stone. It was dosed with a Taylor circular spray nozzle with a cam device for regulating the head on the nozzle. The effluent from the Emscher tank was applied to the filter. Operation began in September, 1913, at a nominal rate of 0.75 mil. gal. per acre daily and this rate was maintained till April 1, 1914, when it was in- creased to"l mil. gal. per acre. On August 1, the rate was still further increased. These rates are actual net yields. The work of the filter was very satisfactory. Suspended mat- ter varying between 70 to 210 p. p. m. was applied, the removal varying from about 45 per cent, to an increase of 76 per cent, during XVI the unloading period in April, 1914. Nitrification became well es- tablished within a few days after the start and has been well maintained since, the nitrates in the effluent varying from 10 to 20 p. p. m. on the average. Putrescibility and dissolved oxygen samples were taken four times daily at 3 a. m., 9 a. m., 3 p. m., and 9 p. m. The former were incubated at room temperature for 10 days. For the entire period of the operation of the filter an average relative stability of 73 was obtained. But during May, June and July, the stability was 94. The time required to ripen, and the spring unloading in April lowered the stability for the flr^t six months. There appears little doubt but that a rate can be main- tained of net yield of 1 mil. gal. per acre per 24 hr. on a bed 6 ft. deep, with gbod results, giving practical stability once the filter has ripened. The performance of the filter was best emphasized by the re- duction in oxygen requirements. Approximately 1000 p. p. m. of oxygen were required for complete stability of the crude sewage from Center Ave., whereas the average requirement for the filter effluent was about 64 p. p. m. or a reduction of over 90 per cent. The filter effluent contained enough oxygen available to meet this requirement during the past 3 months and was stable. These fig- ures were for the strong day* sewage. Free oxygen was nearly al- ways present in the filter effluent which was uniformly clear. The material in suspension discharged by the filter was granular, settling readily. The indications are that a sprinkling filter can handle this liquid and produce an effluent remarkably improved over the orig- inal sewage. Continued operation is needed to settle the question of permanency of capacity. There is evidence that more or less fat is retained at times in the filter. Whether or not this will be removed during the unloading period is a question. Owing to the high temperature of this sewage, cold winter weather is not likely to cause any difficulty in operation. , SECONDARY SETTLING. The effluent from the filter was passed through a small secondary settling basin operated on the Dortmund principle. The detention period was 1 hr. the greater part of the time, and the upward velocity from 2.4 to 3.5 ft. per hr. Under these conditions, the removal of residual suspended solids varieid from an increase of 7 per cent, to a removal of over 50 per cent., based on monthly averages. A longer period and lower velocity is evidently required. Sludge accumulated at a rate vary- XVll ing from 0.5 to nearly 8.0 cubic yards per mil. gal. between individual measurements. Tbe percentage of volatile matter in the sludge recovered from this tank was appreciably lower than for the fresh sludges from the preliminary tanks, while the nitrogen content was distinctly higher. Secondary settling basins appear desirable on account of the large amounts of suspended matter applied to the filter and un- loaded. Owing to the excessive scum formation at times and the comparative difficulty of maintaining single chamber tanks, a dou- ble-deck type of tank seems preferable, even though a shallow sludge chamber necessitates pumping the sludge into the deeper primary settling tanks. OXYGEN EEQUIRED. Comparison of the total oxygen re- quired for the oxidation of the sewage showed a demand at 39th St. on domestic sewage, of about 100 to 150 p. p. m., whereas at Center Ave. the demand was around 1000 p. p. m. The improve- ment by plain settling of the Center Ave. sewage averaged from 18 to 48 per cent. For chemical precipitation the improvement ranged from 22 to 48 per cent. The sprinkling filter did not at all times deliver a stable effluent, particularly at the start. How- ever, during May, June and July, 1914, the oxygen available' in the effluent was greater than the demand, so the liquid proved thor- oughly sta'ble, for the specific tests for biologic oxygen consumed. The larger number of relative stability tests made check very closely, with an average relative stability of 94. , The indications are clear that fine screening had a small effect on improving the stability of the liquid, compared with the im- provement due to sedimentation. FAT REMOVAL. While considerable fat is and has been re- moved by the skimming basins of the various packing houses, and on the Center Ave. and Ashland Ave. outlets, there is a loss due to insufficient basin capacity. The fat contained in the sediment or sludge is also lost, as well" as the fats which are kept in an emulsified state in the hot summer sewage, by the heat of the liquid. The studies on fat removal show a greater removal in the winter than the summer. This is not explicable on the theory of lack of business in summer, but probably depends on temperature. The melting point of the fat extracted by ether from the fatty wastes collected by us is 26 deg. C. or 79 deg. F. In the summer months the sewage is continuously warmer in the day. Cooling the sewage by exposure to air in shallow basins, or artificially, seems to be the XVUl probable solution of this problem. About half the fat was removed on the average by plain sedimentation, while with chemical pre- cipitation about two-thirds was deposited. RECOVERY OF FAT BY ACIDIFICATION. Although there is considerable fat reported in the sludges as directly ether soluble, yet the acidification of the sludge will in many cases greatly in- crease the fat yield. Several random analyses are given on both sludge and seum: Tank Material Ethbb Soluble Pekcbntagb op Dry Weight Remarks As Removed | Acidified C D C Seum ' Sludge Sludge Scum Scum 11.4 23.3 7.4 10.0 10.0 25.6 62.3 69.0 12.6 29.8 Chem. Pre. Bottom Sludge. Grit Cham. E From Gas Vent Acidification of the heavy day sewaige followed by sedimenta- tion for 3 hr. in a Dortmund tank gave an average fat removal of about 69 per cent. The amount of acid consumed is large, 2500 lb. of 100 per cent, sulphuric acid per mil. gal. being necessary to neutralize the alkalinity, while for efficient fat removal qn excess is required. Acidification of the sludge removed by plain sedimentation with subsequent recovery of the grease by the use of some solvent or by distillation with steam is also a possibility. The processes and costs are not as yet established. Various ways have been suggested of acidification, which if ever proved economical, can readily be added to settling works. Acidification of sewage makes an apparent reduction in the biologic oxygen consumption which is remarkable, but this is probably not real, being simply due to a retardation of decomposition fey the sterilization of the bacteria present, the organic material being left in solution. If thoroughly seeded, new bacteria will pick up the work of decomposition, the liquid then proving putrescible. Similar phenomena may happen with chloride of lime. GENERAL CONCLUSIONS. The operation of the Center Ave. testing station has demonstrated that it is entirely practicable to treat to any desired degree sewage, mixed from industrial and domestic origin, as it issues from the Center Ave. outlet. Of the de- vices tried, fine screening, sedimentation in double-deck tanks, and sprinkling filters appear most suitable. The combinations are : XXX 1. Fine screening. 2. Pine screening in combination with sedimentation. 3. Fine screening in combination with sedimentation followed by biological treatment on sprinkling filters and secondary sedimen- tation. Under any circumstances, the removal of settling suspended matter from industrial wastes is needed. Fine screening alone does not appear adequate to meet this test. In almost every ease screens can be installed at the individual houses, and on the fresh sewage will undoubtedly be more effective. Hence screening appears to be an individual problem for each house or firm. Sedimentation re- quires more space, both for equipment and disposal of sludge, and hence is best handled as a community problem, because at most houses space is lacking. In any ease, fine screening is the logical first step, to remove the coarser suspended matter, and will fit with sedimentation in that it materially reduces the scum-forming material. Ultimately biological treatment of industrial wastes is a neces- sity. Sprinkling filters followed by secondary settling tanks seem most desirable. But w;ith a gradual installation, opportunity is afforded on a large scale, to watch the effect of the removal of sus- pended matter from a gross source of pollution. Preliminary screen- ing and settling are necessary as a preparatory treatment for sprink- ling filters, and would be advantageous in the operation of a long intercepting sewer by preventing deposits from a sewage so heavily laden with settling suspended matter. OBJECT OF INVESTIGATION. The purpose of the inves- tigation has been two-fold, first to learn how to relieve the load upon the main channel coming from the organic waste Of this in- dustry and second how to remove the local nuisance from the East and West arms of the South Fork of the South Branch of the Chicago River, and particularly the West arm, known popularly as Bubbly Cr^ek. CONSIDERATIONS INVOLVED. The solution of the problem involves not only a consideration of the.municipal and private sewers in and around the yards and Packingtown, but also the efficiencies of various forms of treatment, the size and location of treatment works, and the relation of different steps in the collection and treatment to the future. Whatever is done must be flexible, readily adapted to future extension and fitting into a comprehensive sys- tem, if it ever becomes necessary. EXISTING SEWERS. The present system of private sewers XX in Pactingtown is generally inadequate for flood flows. Center Ave. sewer is also overloaded at time of heavy rain. The City of Chicago is now planning a new sewer, located to the west of but parallel to the Center Ave. sewer, to run south and relieve the old Center Ave., Ashland Ave. and Eobey St. sewers, and pick up some new territory. EXISTING TREATMENT. At present there -is practically no treatment of the industrial sewage from Packingtown, other than a partial removal of fat by grease skimming basins. The basins are seldom built to retain settling material, except at the hog- houses, and then are insufficient. The screens in use are very coarse and hold back little except intestines. At the stockyards, the Jennings screen is handling the outflow of the Morgan St. sewer. At the other outlets no treatment is given. PILLING BUBBLY CREEK. From the sanitary standpoint the filling of Bubbly Creek would be desirable, although mere filling alone would simply transfer the nuisance from one locality to another. "With suitable treatment of the industrial wastes, it is entirely proper that this dead arm be filled and that the area thus reclaimed be used as a site for sedimentation tanks. The areas reclaimable are : A. From the end of the West Arm to Ashland Ave. — 11.5 acres. B. From the end of the West Arm to W. 39th St.— 16.5 acres. C. From the end of the West Arm to the Forks — 24.3 acres. The fill required can be obtained in part from the construction of the proposed Center Ave. sewer, the proposed sedimentation plant, and from the dumping of ashes. The sedimentation plant itself for industrial wastes only will require 6 acres, and a reserva- tion of 3 acres for future use. The points to be cared for are : 1. The flow in the West 39th St. conduit should be in- creased, by the introduction of the sewage from Robey St. and industrial sewages from the East thereof, including the stockyards and Packingtown. 2. The sewage from the stockyards and Packingtown should be treated by fine screening and sedimentation at once, regardless of the outcome of the Federal suit. 3. A portion of the bed of the West Arm should be re- served for the sedimentation plant. 4. Intercepting sewers will be required to collect the XXI sewage and to divert tlie wastes of Packingtown from the new Center Ave. sewer into Ashland Ave. BEST PEOJECT. Consideration of various alternatives (see Chap. XVII) leads to the belief that the best project comprises an intercepting sewer for industrial wastes and domestic sewage extend- ing from Halsted St. to the west end of the "West Arm, the diversion of all Packingtown sewage from Center Ave. sewer to Ashland Ave. sewer, fine screening at the individual houses or firms, sedimentation at the outlet of the intercepting sewer, in a community plant built in the bed of the "West Arm west of Ashland Ave., an outfall sewer into the "West 39th St. conduit, receiving the effluent of the plant, and the diversion of the Robey St. sewer into the same conduit. The cost of this project is approximately $985,000, exclusive of legal, engineering and land expenses. The new Center Ave. sewer, under this project, would receive no industrial waste from the stockyards or Packingtown. Such a project for screening and sedimentation handles the wastes as separately as possible, with the presence of some domestic sewage, and is flexible with regard to the future. The ultimate solution will require biological treatment. As kpace is lacking in the immediate vicinity of Packingtown, this means an extended intercepting sewer running westward from the outfall of the sedimentation plant, which would carry the screened and settled sewage to a pumping station where the sewage would be pumped onto sprinkling filters. The effluent would require settling in secondary settling tanks. Sludge drying beds, an outfall sewer, and other collateral works are required. ' This fits directly onto the set- tling plant, just described. Screening and sedimentation are neces- sary as a preliminary treatment, and will materially aid in maintain- ing the intercepting sewer free from deposits. The additional cost for the intercepting sewer, pumping station, sprinkling filters and collateral works is approximately $3,600,000, exclusive of legal, engi- neering and land expenses. , BURDEN OF COST. There are many preliminary questions to be solved of legal and financial nature, as well as engineering details, before construction can commence. Particularly important is the distribution of the burden of cost. Undoubtedly the law intends that the larger burden shall be carried by the industries, for the organic law of the Sanitary District is based on the theory that a channel will be constructed solely for the reception of do- mestic wastes. RECO"VERIES. The results of the testing station do not indi- cate hope of recovering much material of value, from the commer- xxu cial standpoint, other than grease. It is possible that use may be found for the sludge as filler for fertilizer, and that the screenings may be burned. The smaller houses should endeavor to save all offal or other material now reaching the sewers, which is saved by the larger houses, by some cooperative arrangement. The chief object to attain here is not commercial recoveries, but the destruction of a nuisance of long standing. Improved conditions of sanitation, and standards of civic cleanliness, demand this. CHAPTER I. THE STOCKYARDS AND PACKINGTOWN INDUSTRY. For years Chicago has been the center of stockyards and pack- ing interests. A large community of plants has grown up in the vicinity of 39th and Halsted streets on the South Side, occupying over one square mile, with stockyards and packing houses, and including all the scattered plants, nearly one and one-half square miles. The industry has grown from small beginnings, with various shifts in location. In 1848, John B. Sherman started the Old Bull's Head stockyards at the corner of Madison street and Ogden avenue. This site proving unsatisfactory, a new site was selected at Cottage Grove avenue and 30th street, known as the Sherman Stockyards. In 1865, the site was again changed to a half -section bounded by '40th and 47th streets, and by Halsted street and Center avenue, at that time largely a swamp far outside the city limits. At first, the yards covered 120 acres, with 2,000 cattle pens, which grew in 1901 to 340 acres with 5,000 pens. From 1865 on, the industry developed in one central location. As nearly as can now be learned, drainage was into the south branch of the Chicago Eiver, a very sluggish stream, utterly inadequate to receive the wastes of even a young industry. Complaints began early and continued for years, lessened somewhat by the endeavors of the packers to recover more completely the by-products. In the early days, the problem of disposing of the offal resulting from the slaughter of cattle, sheep and hogs, was very troublesome. Even its value as fertilizer was unknown. Blood was allowed to run into the river, while heads, feet, tankage and general refuse were hauled out on the prairie and buried. A few began to dig up this material, and convert it into glue, tallow, oil and fertilizer' in small factories. For awhile the offal was given to any one who would cart it away. Various products of fair quality were made in small factories, at ' large profits which attracted so much competition that buyers bid up the price of offal to a high figure "With the perfecting of a direct heat drier in 1877, the packers began to enter the fertilizer industry, making the profits for them- selves. Gradually other by-products were utilized, by the packers themselves, so that to-day practically every part of the animal is used in some way in factories belonging to the large packing houses. In the small houses, slaughtering largely for intra-state or local trade, early conditions still obtain. Blood, ofEal, and even tankage frequently are discharged into the sewer in a way not tolerated, in the large houses. To-day in the large houses, an attempt is made to save practically everything except the squeal, and even that the packers jokingly say is canned by a phonograph. In the. pursuit of returns, grease. is skimmed from the main sewer outfalls at Ash- land and Center avenues and from the immediate surface of the river. The endeavor of the industry, to secure economic recoveries has not, however, carried the efforts so far as to retain material of im- portaniee, not necessarily from the manufacturing staiidpoint, but from the standpoint of sewage disposal. There is still much ma- terial which passes away, in the aggregate thousands of tons a year, to which the practical manufacturer attaches little importance. To the sanitary engineer these wastes, containing large amounts of sus- pended matter with a liquid highly putrescible, are of great im- portance. For many years there has been a strong feeling that industrial waste of highly putrescible character is concentrated in the region along the South Fork of the Chicago River known as Bubbly Creek, yet no definite data had been found on which to base any recommendations for its treatment or use. Many sanitary engineers of standing have felt that the legal minimum rate of flow prescribed for the Sanitary District by its charter was too low to care for the industrial load on the main channel in addition to the sewage of purely human origin. "With the sluggish flow now existing in the West Arm and the moderate flow in the East Arm, it has been evident that sedimentation does occur both of organic and mineral suspended matter. The velocities of flow have not been made sufficiently high to scour. The condition of the South Fork has been vastly improved by the construction of the 39th street pumping station, and the use of the flushing pumps but permanent improvement will not ensue until the quality of the waste discharged into the river is distinctly improved, and large amounts of suspended matter removed. From time to time substantial deposits have been dredged out by the United States, the City of Chicago, the Sanitary District, and private corporations. The amount of material so removed amounts to several hundred thousand cubic yards, since the opening of the Drainage Canal in 1900. Banks of foul putrefying organic matter may still be seen at intervals along the South Fork, in particular along the West Arm, near Ashland avenue, where there is a bank in the middle of a draw span. A record of soundings in the West Arm, west of Ashland avenue, shows that over a period of thirteen years, from 1895 to 1908, the shoaling has continued at a rate of 0.42 feet per year. In this dead end, fed solely by the Ash- land avenue and Eobey street sewers, and a little surface water from the original bed of the old "West Arm east of "Western avenue, the source of the deposits is at once evident. During the work pre- liminary to the opening of the conduit from the "West Arm through Western avenue to the Drainage Canal, the Sanitary District re- moved approximately 100,000 cubic yards of material from the river west of Ashland avenue. Of this it is estimated that over 50 per cent, was typical sludge of sewage origin, in various stages of putrefac- tion. PREVIOUS INVESTIGATION. Early in the history of the Sanitary District, it was realized that something must be done to improve the condition of Bubbly Creek. In 1890 steps were taken by L. E. Cooley, then Chief Engi- neer, towards a comprehensive investigation covering gaugings of sewers and chemical analyses. Of this work only a few records are available, principally a table of analyses (Proceedings, 1891, p. 183) copied herein (table 1), and some plots of gagings. The analyses of the Stockyards sewage (Ashland avenue and Brennock sewers) made by Prof. J. H. Long agree very closely with the present day results. At the same general period a report was made by W. E. Worthen, then Chief Engineer (Proceedings 1891, p. 140-4), in which the construction of an intercepting sewer or conduit was recommended of a capacity of 38 cubic feet per second from Hal- sted street westerly to receive all the Packingtown sewage. Flush- ing pumps were also proposed, the whole to discharge into the Illi- nois and Michigan Canal. Apparently, however, no attention was paid to the possible effect of this discharge on the canal. Ten years later, in the report Of the Sanitary Investigations of the Illinois Eiver and its tributaries (Illinois State Board of Health, 1901), Prof. J. H. Long made a special report on the chemical and bacterial examination of the waters of the Illinois Eiver and its principal tributaries (pp. 66-67). Comment was made on the condi- tions existing in Bubbly Creek and the North Branch as follows : "An extremely important factor in determining the char- acter of the Bridgeport discharge is the drainage from the stock- yards sewers, and in former years the output of these was much greater in amount of organic matter than at the present time. In 1886 I made some examinations of the flow of the main sewer, and found that the organic matter discharged by it when calcu- lated to the dry condition amounted to over 112 tons daily, which is about equivalent to the closet sewage of a population of 1,350,000. This large content was exceeded greatly in earlier years when the commercial value of the waste was not appre- ciated. Several years later, in 1890 and 1891, I had occasion to make extended investigations of the character of the sewage reaching Bridgeport from several quarters. Over twenty com- plete tests were made on the sewage discharged from the Bren- nock and Ashland sewers combined, the samples being collected in such a manner as to secure a very accurate and fair average for the flow of the 24 hours. With a mean discharge of 1,336,000 cubic feet per day, the organic matter present was 2,428 parts per million, corresponding to 91,850 kilograms or about 101 tons daily. At the same period the discharge of the Halsted and 39th street sewers was 9.3 tons of dry, organic matter. The total nitrogen from the Ashland and Brennock sewers, counted as ammonia, was 418.5 parts per million, amounting to 15,820 kilograms, or 17.4 tons daily. From the Halsted and 39th street sewers the amount was 37.2 parts per million, correspond- ing to 1,406 kilograms daily, or 1.25 tons. For the two sewer systems the ratio of ammonia to total organic solids is nearly the same, and high enough to indicate the essential proteid char- acter of the waste. "I believe these results may be applied to present condi- tions (1901.) with a fair degree of accuracy. While many im- provements have been made in processes for utilizing stock- yards waste, the gain is practically compensated for by the in- creased slaughtering of cattle and hogs. Extensions in the Ash^ land avenue and Halsted street sewer systems bring also a great- ly increased amount of sewage from points south of the stock- yards, so that the final discharge must now be above the figures given. Approximately, then, the flow at Bridgeport can be taken as made up of city sewage containing 150 tons daily of dry organic matter and the combined stockyards and Ashland and Halsted sewers, containing about 110 tons daily, but from the latter must be deducted the fraction of house sewage it contains, which in dry organic matter must amount to about 20 tons, as the contributing district has a population of about 200,000. Supposing the above assumption as to the constant flow from the stockyards correct, we must add 90 tons of dry organic matter to that from the city flowing toward the Bridge- port pumps." . The Board of Health of the City of Chicago has from time to time made cursory examinations of the slaughter houses from the standpoint of sanitary conditions (cf. Reports Dept^^ Public Health, Chicago, 1904-1910). Attention was principally directed to reducing the odors, the larger volume of which arise from the fertilizer driers. The nuisance from. Packingtown to-day is largely aerial. The odor is unmistakable, and travels miles under favorable atmospheric con- ditions. RESULTS OBTAINED. Notwithstanding all these investigations, little has been done from the standpoint of improving the condition of Bubbly Creek by the treatment of the pollution. The object of our investigation vras to establish definitely the probable amounts of waste to be expected and suggest the ways and means of handling the problem with a view to immediate action. PRESENT INVESTIGATION. An extended investigation was begun early in January, 1911, to cover all the industrial wastes which enter the Drainage Canal. Lists of probable sources of wastes were prepared, and as time has per- mitted, the localities have been examined, and samples collected. So far, the detailed investigation has been confined to the stockyards region and its immediate vicinity. Conditions along the Chicago River have changed so markedly in the last twenty years, that industrial practices which once passed unnoticed are fast becoming a serious problem. Again, with the occupation of the water-front, adjacent properties are sometimes directly injured by deposits from a neighboring factory up-stream. Hence the growth of the city and the accompanying congestion have brought about changed conditions, which miist be faced in order to avoid conditions worse than the present. PURPOSE. The purpose is not to drive manufacturers or industries away, but to secure such co-operation as will gradually improve existing conditions in an economical and scientific way. Treatment of indus- trial wastes is vitally necessary to prevent the canal from becom- ing a dumping ground for all kinds of industrial refuse, and thereby increasing the load on the canal itself. IMPROVEMENTS. However, it is frequently impossible at first to suggest off-hand the necessary improvements in detail, as none of the houses exam- ined so far had exact knowledge of the flow or quality of their dis- charges prior to examination by us. Measurements and tests are necessary, sometimes over an extended period. Plants vary, as well as operating conditions. Continued co-operation, study, and im- provement are therefore necessary. 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En « o p m o IS < pj-g n o o o IS o < Ph O a . o ^ S ■a ^ 1 uj c ft! fc- Ul _l £ oa CQ 03 < O _« H o OT W 1 1^ o ^ o £ ^ £ hj ■a ' s M 1 fq o o o fl p^ o o ooooo . oa t^ »0 »i3 00C ooos tO'^eoc ooooooo o o o o o o o Oi^oq^o^oa^QOos^c m •* COOCO'*M(MCO _ _ ooc OSOOOQOOO C0O5'cOCo'riH''00T(H" t^ m t^ T-H i> CO CO M Ol CD "* (N (M CO ooooooo ooooooo oi o cx) -^ CO IN m .CO-*-* .CQ03C0 N COtH Soo oo •OOOCO : cTi-h"-* .CO --I CO 1-H coo §oo oo .■*ioco :-*'oi>r .00 CO CO rH COOa • oooo • oooo ■ oa cooot* ooOtHOwom ; OOIMCOCO .. — th ;t*-*cooo ooooooo ooooooo (M >0 (M t^ 00 1-1 CO "^lOO-t-r-^i-TiC C'llOlXMO C<100 IN 00 "O ■* CO ■* cooo 1-ti-H (N^- ■ oooo • OOOO • O -* ■* 1-H ■ CD CO i-Tco ■OOOO* CqcNCOOO OOOOOOOOOOOO OOOOOOOOOOOO 0_0_0_0_0_0_^0_0_0_0_0 0_ lo i-T oa" o i>r CO i>- CO »o t>^ 00 !2 COQ**CDlDOQcD (Mi-I 0-* oiro o MOW ^o MOS i 29 third compartments was very fine grained, brown in color, resem- bling finely separated loam (table 8). The amount was compara- tively small, a total of 3.8 cu. yds. per Inillion gallons accumulating during a period of test lasting over 3 months. The percentage of removal of suspended matter ran from — 36.2 to -f 80.0, depending on the amount present and the condition of the basin. With a maximum of I3O8 p. p. m., 73.1 per cent, was removed. With a minimum of 34 p. p. m., 41.2 per cent, was removed. On the average with a content of 548 parts per million, 63.8 per cent, was removed. LABOEATORY TESTS ON SETTLING. Laboratory tests on settling demonstrate that most of the settling suspended matter drops out in the first 5 to 10 minutes of quiescent settling. SLUDGE. Scattered analyses (table 8) indicate a sludge some- what more dense than the sludges from the 39th street Sewage Testing Station, the proportion of volatile matter being, usually greater. The nitrogen content and fats average about the same. The sludge from the first compartment contained hair. In general, all this sludge had an offensive, putrid odor, entirely different from the material collected at 39th street. SCREENING. In 19l3, an endless band screen was installed on the outlet of the Morgan street sewer by the Union Stockyards and Transit Co! from the design of Mr. C. A. Jennings. This screen has been operated almost continuously since, various meshes and punched plates being tried. The results of the tests made by the Sanitary District are given in Chapter XI. The removal of sus- pended matter does not appear to be as great as by sedimentation. CONCLUSIONS. If the sewa,ge of the Stockyards proper be treated separately, settling basins should be built given a nominal settling period of at least 1 hour for the higher dry weather flows. Sludge storage for at least 4 eu. yds. per million gallons flow should be provided, with a period of at least 8 days, and better, 2 weeks, if arrangements are made for carefully avoiding any septic action, by cleaning very frequently. The sludge should drain readily, and after pressing can probably be burnt. The analyses show a low ni- trogen content, so that utilization for fertilizer is doubtful. The appearance is also against this use. It is, htowever, better to build a shallow doubleTdeek tank to aid in retaining settled matter, and ob- tain thereby cleaner effluents. By enlarging thfe sludge storage in a double deck tank, digested sludge can be had. Fine screening is also effective but will not remove as much of the suspended matter as sedimentation. It would, therefore, seem desirable to use a combination of fine screening and settling. 30 UJ ca < ■3 g rJ^ ■*s ■^ S w 03 a ? g <0 bO 3& § T3 Ti . .-1 1 OcSS il *o3 Hi"- 1 >> 'S 1 ?'2 b-i ^ir H H uA C3 . fi oOtoOThoi tH . 1-1 IM Ph <^i-icococo . H o !0-* (M ioa> H /"t- CD 10 to t- CD(N I-:; h 1^ ^§ <1 H g ■« H -§ n P-l o Ph . ^ ^>0!0-*>0 cq •*o 1 ■-1 CQ (>i CO ro N Oo'r-i |x| S f^ a "S *■ il •^ 0000 q 00 ^ 0>rH OiCO 0° 00 OS 00 OS CO OS 00 fe ^ 00 00 CO H Q p '.a^ a sssss 10 ■^ CO OQ Ort o oaiS 1-1 ,-( r-4 t-H ^ T-t rf l-I OQ pq >H P. ^M < aasi c 3 •s m CHAPTER IV. DESCRIPTION OF TESTING STATION. GENERAL. The original plant, built in 1912, consi.sted of a grit chamber, two settling tanks of the Dortmund and Emscher types, respectively, and six sludge filters, together with accessory Plate 1. Center Ave. Testing Station from North. pumping and controlling apparatus. During 1913, extensive addi- tions were made, including a motor driven rotary screen, apparatus for determining the loss of head through screens of various mesh, a Plate 2. Center Ave. Testing Station from South. 32 second tank of the Dortmund type, apparatus for the application of chemicals to the sewage as an adjunct of tank treatment, a sludge press, a sprinkling filter and secondary settling basin. Additional pumping capacity was also provided. The general arrangement of Plate 3. East Arm of South Fork of South Branch of Chicago River. Note. View taken from Racine Ave. bridge looking East. Grease skimming basins in foreground, at outlet of uenter Ave. sewer, power house in background . U. S. & T. Co. the final plant is shown in Figs. 5 and 6, and in the accompanying illustrations, Plates 1, 2 and 3. SUPPLY OF SEWAGE. Sewage flows by gravity through a six-inch tile pipe from the Center avenue sewer, at a point about one foot above the invert, and discharges through a six-inch shear gate into a concrete channel in tbe pump well. Any surplus over pump- age discharges over a waste weir at one side of the channel into a drain to the river. All sewage pumped passes through a screen, in- clined at an angle of 30 degrees with the horizontal in the direction of flow, composed of %-inch roiind bars set with %-inch clear open- ings. The screen is 9% inches wide. It was cleaned from time to time with a rake. A vertical centrifugal pump with a rated capacity of about 250,000 gallons per day discharges through a 4-inch force main with branches to the grit chamber and screen house. The pump is direct connected to a 3-| h.-p., 3 phase, 60 cycle, 220- volt induction motor running at a speed of approximately 850 r. p. m. located in a small wooden shed covered with corrugated galvanized iron built directly over the pump-well. This arrangement keeps the motor and controlling switch dry and in good working order at all times, with excellent operating results. The pump works against a 33 maximum static head of about 19 feet, and, being always sub- merged, requires no pritaing device or foot valve. In order to operate the rotary screen at a high rate without shutting down the rest of the plant, a 2i/^-inch Morris horizontal centrifugal pump was provided, of a nominal capacity of 260,000 gallons per day at 720 r. p. m., connecting with the force main of the original installation for flexibility of operation. The pump is belt connected to a 3 h.-p., 60 cycle, 3 phase induction motor, with a speed of 1,800 r. p. m., mounted on the floor of the motor house. GEIT CHAMBER. One branch of the force main discharges into a stilling basin built of a half barrel, carried by the trestle sup- porting the grit chamber. As the speed of the motor is constant, the pumpage is regulated by a valve in the force main. The stilling basin feeds the grit chamber proper through a 4-inch pipe, entering at the bottom near one end. The grit chamber is of tank construc- tion, of 2-ineh stock, 20 ft. 6 in. long, 6 in. wide inside, varying uni- formly from a depth of 19 in. at the inlet end to 13 in. at the outlet. Sludge is removed when cleaning through a 4-inch waste pipe and valve near the inlet end. During November, 1912, a thick, greasy scum persisted on the surface of the grit chamber. To retain this, a scum board was placed 6 in. from the outlet, dipping about 2 in. below the surface of the sewage. Ordinarily the surface of the sewage is about 2% in. below the top of the chamber, giving a capacity of about 87 gallons. The effluent flows through an open wooden flume, 6 in. square inside, to the controlling apparatus. CONTROLLING APPARATUS. The controlling apparatus is housed in a two-story frame building, covered with corrugated gal- vanized iron, 8 ft. by 10 ft. in plan. The flume from the grit cham- ber enters the second story and discharges directly 'into the main orifice box, of standard tank construction, containing three compart ments for vertical orifice plates, on which the head is maintained practically constant by a waste weir extending the entire length of the orifice box. The surplus sewage passes through a 3%-in. pipe overflow to the floor below. The orifices are always operated sub- merged, the effective head being regulated by adjustable brass weirs. The orifice compartments discharge directly into open wooden flumes, 31/2 in. wide inside, leading to the various tanks. All waste from the overflow pipe is measured by an orifice box, containing three 1%-in. horizontal circular orifices, the head being read hourly to determine the total amount of sewage passing the grit chamber. OLD DORTMUND TANK (TANK D). This tank, located iust east of the control house, is a circular wooden tank (Fig. 7), with an inside diameter of 10 ft. and a total depth of 15 ft. 21/2 in- below the 34 1 i tl 1 /^^^^^ ^ ^. f - ^^^ '^ ^1 ( * ) fB"^ J z %JLM 1 c « H ■a c 3 E b □I il IVofer Line^ ^ ; SVatel^/n V/7f/ e 03 '3 ^ P bO cccoeo • OlOOl'^t-Oi-i'^WCO OJOCD Q BI H H I— I o m Q D OSOJi-i i-HCOCO 00OU3 Or-irH COO'-'NOOOOOCCQOtO.HeD Tl( r-HO N t* N N .-HOJ r-l 00 1> 10 ^O ^ ^ ^ ^ ^ ''J* ^ ^P ^ ^ .OST-li-lfHOr-li-tOOtH ^ com-* P rHNW «^COU31OCOt}4C4IOU30000 coccPJNoawcocow nco « DO 5 ■B ■*«^ iz; d '3 03 £ S COOOfD b 3 < !f2NiO) > •^ :^y'^ Alka inT of C ■rt ►1 In ^ § :§ g •s ,o 1^ ^ m (3 CO •S H° C3 » d o ■a a s 3 § g o ■a »,9 « (!< S &S° g a§^ rt Q to 12; en 0) ■< 5 1 iz; o 1? ■^1 O '^'3 ^o CO Date 912-1 H O 05 W5 03 O O tM CO O O i-H CO ^ CD 05 (Nt^lO lO O -^ CO 00 l> ■^ CO (M O CO T-H OiOCD COOT-H(MOQQOOCOOOlOt-lCO P H '-1 COCO (NOi-icooocooO'^t-Haii>LO OCDOiiOiOOcDI>CCO^>OCOC01C^OCOIOCD«0 ^COO lO (NIM(MC5lM P5 W 1-1 l>00001>-lr~f-!OQ000 3 80M i-lO cqaDOCoypiOeocou^Ocoo osoiOrHOi-joaiQoojoio ,-li-lrHCitDi*oortT-i(a^ CaOOtVOOOOCDOOOOOSt^OS «llr~Oi03rHg5COtHW*iHO Thi-(CC(MCOOCOi^lOiHNrt cccccc'^co'^'^'^cococon C13 JL ^2 I^ ,o OQ • ■ ■ w "C5 ^t^ T-(CO Oi-l-l Q ■ ■ • IZi «J oocoi*(rot~coiNcp^iOT((o (MC^NC^CCrHTHOOiHNN OgjMlOOOINtlN^CDfflO) i-)Oi— li-; t>; l>i 00 H I" ,J!i a. o ff OQ ^ CD 61) eS >. ^ r ai •«-' r/> r o 73 El « O O) re i]> ■> o < ^ ■^ "SS »\< 52 ASHLAND AVE. SEWAGE. As \eomsiderable packing house waste enters the Ashland Ave. sewer, samples were col- lected for two weeks in September, 1913, under identically the same conditions of sampling and division between day and night flow as at Center Ave. The results, given in table 16, and compared with similar analyses for Center Ave., show the sewages at Ashland Ave. and Center Ave. to have substantially the same composition and character. The Ashland Ave. sewage is somewhat lower in chlorine, possibly because of the absence of any urine from Stock- yards drainage. TABLE 16. COMPAEATIVE ANALYSES OF CRUDE SEWAGE FROM CENTER AVE. AND ASHIAND AVE. SEWERS. PARTS PER MILLION NITROGEN AS Alk. 1913 CUo- as of Total Free Nitrites Nitrate Oxy. nne CaCos Org. Amm. Con. Total M Vol. 1 Fixed DAY SEWAGE ASHLAND AVE.— WKEli Sept. 22 65 19 .16 1.48 211 850 830 560 270 400 24 83 21 .20 1.48 247 1000 810 640 170 340 26 74 22 .16 1.80 265 950 880 600 280 420 29 69 19 .24 1.46 250 880 700 520 180 330 Oct. 1 71 21 .32 1.23 267 920 1100 970 140 320 3. 74 19 .16 4,40 229 940 830 650 180 340 Average 73 20 .21 1.97 245 920 860 657 203 358 CENTER AVE.— WEEK Sept. 22 77 19 .52 3.26 248 1070 690 480 210 240 24 86 18 .52 2.26 275 1060 720 600 120 320 26 75 21 .52 2.74 282 1250 660 510 150 330 29 58 18 .40 1.40 221 900 450 380 70 270 Oct. 1 68 18 .32 2.09 227 850 420 410 10 240 3 73 26 .24 1.90 262 1210 670 520 150 320 Average 71 20 .42 2.27 252 1060 601 483 118 287 ASHLAND AVE.— SUNDA Y Sept. 28 172 108 64 Got. 5 188 92 96 Average 180 100 80 CENTER AVE.— SUNDA' ?■ Sept. 28 100 84 16 Oct. 5 88 72 16 Average 94 78 16 NIGHT SEWAGE ASHLAND AVE.— WEEK AND SUNDAY Sept. 22 32 16 .06 1.33 60 500 272 128 144 230 24 34 18 .08 0.78 61 590 192 132 60 220 26 33 19 .12 0.66 81 530 360 88 272 250 28 244 116 128 29 35 17 .07 0.67 76 530 212 132 80 250 Average 34 18 .08 .86 70 537 258 120 138 237 CENTER AVE.— WEEK AND SUNDAY Sept. 22 100 56 44 24 152 124 28 26 104 88 16 28 324 144 180 29 140 108 32 Average 146 99 47 53 CHAPTER VI. GRIT CHAMBER. GENERAL. Tlie purpose _of a grit chamber is to remove the heavy mineral matter in the sewage, especially the detritus entering the sewers at time of heavy storms, without causing deposition of organic matter, which usually can best be handled at a later stage of treatment. A comparatively high velocity is essential to prevent the settling of excessive amounts of lighter organic materials. The grit chamber was operated at a rate of from about 105,000 to 150,000 gal. daily with an average flow depth of approximately 13| in TABLE 17. GRIT CHAMBER. Sludge Accumulation and Analyses. Cu. Yd. Per Calculated to dry Weight MU. Gal. Spec. Grav. Per Cent Mois- Percentage Date Since Ether Solu- ble Remarks last Since ture Nitro- Vol. Fixed clean- start gen Matter Matter ing 1912 Oct. 25 0.016 0.016 1.31 48.3 0.72 23 77 1.7 Cleaned Nov. 9 0.062 0.028 1.23 0.80 2.0 Nov. 22. ... ; 0.025 0.027 1.12 . . .- . 1.68 58 42 2.8 Dec. 3*. . . . 0.000 0.022 Dec. 27 0.012 0.021 1.30 44.6 1.04 33 67 2.2 1913 Jan. 17 0.032 0.023 1.24 50.7 0.88 34 66 2.1 Feb. 10 0.026 0.023 1.13 55.4 0.88 40 . 60 2.8 Apr. 9 0.028 0.025 1.50 34.9 0.56 13 87 1.2 May 1 0.031 0.025 1.33 50.0 0.88 30 70 1.6 June 24 0.017 0.024 1.34 44,6 0.64 17 ' 83 1.2 Aug. .8 0.013 0.022 1.44 39.6 0.80 19 81 0.9 28 0.029 0.022 1.34 44.3 0.64 23 - 77 5.5 Oct. 2 0.018 0.022 1.39 29.2 0.56 10 90 1.5 24 0.022 0.022 1.36 47.8 0.76 26 74 1.6 Nov. 13 0.023 0.022 1.32 49.1 0.84 27 73 1.9 Dec. 10 0.016 0.022 1.23 54.9 0.88 34 66 1.8 1914 . Mar. 12 0.011 0.020 • • • • .... Apr. 21 0.044 0.021 .... June 26 0.019- 0.021 .... Average 1.31 45.6 0.84 28 72 2.1 * Estimated result — Sludge run out by filter attendant without measuring. 54 Making no allowance for the reduction of volume by deposits this variation in flow corresponds to velocities from 17 to 25 ft. per min., or from 87 to 125 mm. per sec, with a short detention period, vary- ing between 70 and 50 sec. SLUDGE. The grit chamber was cleaned at intervals of two to eight weeks, the amount of grit deposited being measured and sampled for analysis. These results (table 17) indicate a sludge of high specific gravity and low moisture content. The content of nitrogen and ether soluble matter was also low, approximating the grit chamber sludge at 39th St. The percentage of volatile and fixed matter varied considerably, however, at times the volatile content being very high for a true grit, and in general the percentage of volatile matter being higher than at 39th St., with the high veloci- ties. The sludge consisted largely of black-stained sand with vary- ing amounts of paunch manure and animal droppings. The amount of detritus was slight, averaging about 0.021 eu. yd. per mil. gal. With an average specific gravity of 1.31 and a moisture content of 46 per cent., this corresponds to a removal of about 3 p. p. m. of suspended matter, or less than 1 per cent., based on the average composition of the raw sewage. The rate of accumu- lation has varied between individual cleanings. The accumulation at the 39th St. testing station at high velocities (0.016 cu. yd. per mil. gal. at 142 mm. per sec), is lower than at the Center Ave. test- ing station, but the velocity was appreciably less, so that the results are not wholly comparable. The rate of accumulation of grit was probably less than under working conditions in an actual plant receiving the entire flow of the sewer, as the pipe supplying the testing station leaves the sewer at a point above the invert, and thus may not receive its propor- tionate share of heavy grit from the bottom. The sludge was simply flushed from the grit chamber into the waste pipe and discharged without further treatment. It was dry enough, however, to be handled by shoveling, and was comparatively inoffensive. EFFLUENT. The amount of suspended material removed by th^ grit chamber was a' very small proportion of the total suspended matter, and accordingly the reduction in suspended matter was merely nominal. Determinations of suspended matter were made, the monthly averages being given in table 18. The percentage re ductions in suspended matter are rather erratic, showing an appar ent increase in some months, whereas in other months the removal varies from 3 to 22 per cent. Tn December, 1912, to determine- 55 TABLE 18. GRIT CHAMBER. Reduction in Suspended Matter, Based on Monthly Averages. Suspended Matter Parts Per MU. Per Cent Reduction Date Influent Effluent Total Vol. Fixed Total Vol. Fixed Total Vol. Fixed 1913 Day Sewage — Sundays Omitted 702 660 543 510 159 150 670 605 519 455 151 150 5 8 5 11 5 Feb Mar 1-8; 24-31 ' 691 451 140 626 484 142 6* 7* 1* Apr 556 422 134 523 390 133 6 8 1 May 658 470 188 597 450 147 9 4 22 June 603 428 175 580 437 143 4 4* 18 July 568 428 140 543 420 123 5 4 12 Aug 574 413 161 554 406 148 3 ,2 8 Sept 621 498 123 577 440 137 7 12 11* Oct 519 617 415 481 104 136 528 556. 420 437 108 119 3* 10 1* 9 4* Nov 12 Dee 595 476 119 502 400 102 16 16 14 Av. 1913. . . . 605 461 144 572 438 134 6 6 7 Night Sewage — Sundays Ir icluded. 225 167 152 117 73 50 204 150 147 102 ■ 57 48 9 10 3 13 22 Feb 4 Mar. 1-8; 24-31 163 116 47 157 108 49 4 7 4* 121 238 84 146 37 82 125 185 79 122 46 63 3* 22 6 16 24* May 23 June 162 103 59 156 103 53 4 10 July 148 92 56 134 89 45 10 3 20 Aug 142 95 47 136 92 44 4 3 6 Sept 153 110 43 156 117 39 2* 6* 9 Oct 128 93 35 130 92 38 2* 1 8* Nov. . 148 107 41 133 99 34 10 8 17 Deo 165 120 45 160 119 41 3 1 9 Av: 1913. . . 163 112 51 152 106 46 7 5 . 10 1912 Day and Night (24 Hour) Sewage- — Sunda ys Omitt ed Oct 644 589 518 430 126 159 669 644 547 480 122 164 4 9* 6* 12* 3 Nov 3* Dec 540 420 120 524 410 114 3- 2 5 1913 Jan 542 413 129 517 398 119 5 4 8 Feb 483 366 117 446 332 114 8 9 3 Mar. 1-8; 24-31 433 329 104 456 347 109 5*- 5* 5* Aor 394 500 296 350 98 150 375 445 275 328 100 117 5 11 7 6 2* May 22 June 444 310 134 432 319 113 3 3* 16 July 418 312 106 389 297 92 7 5 13 Aug 425 302 123 407 296 111 4 2 10 Sept 437 350 87 411 316 95 6 10 9* Oct 374 444 295 343 79 101 381 401 298 313 83 88 2* 10 1* 9 5* Nov 13 Dec 436 345 91 376 298 78 14 14 14 Av. 1913. . . . 444 334 110 420 318 102 5 5 7 Note: I Jay Sewage includes samples from 8 A. IV [. to 10 ] P. M. inc ,1. 1 ^ight sewage includes samples from 11 P. M. to7 A. M. ii icl. * Denote s mcreas e. 56 whether the method of sampling caused the increase in suspended matter occasionally noted, samples covering 8 hr. intervals were taken over a period of two weeks with particular care. The average results on suspended matter and chlorine are shown in table 19. Since the same discrepancies occurred, the errors previously found are probably those of sampling. In general, a somewhat higher reduction in fixed matter was noticeable as would be expected, but this was not universally true. TABLE 19. SUSPENDED MATTER AND CHLORINE IN GRIT CHAMBER EFFLUENT. Dec. 10 to 23, 1912. 8 A. M. TO 4 P. M. 4 P. M. TO 12 Mid. 12 Mid. to 8 A. M. Susp. Matter Chlorine Susp. Matter Chlorine Susp. Matter Chlorine Crude Grit Crude Grit Crude Grit Crude Grit Crude Grit Crude Grit. 633 668 1044 1063 521 546 994 961 238 226 627 627 SCUM. About the* middle of November, 1912, a heavy greasy scum formed on the surface of the grit chamber. To retain it from passing into the controlling apparatus, a baffle dipping about 2 in. below the surface was installed, 6 in. from the outlet of the chamber. The scum collected in a cream colored mat, at times coveriag the entire surface of the chamber to a depth of 2 in. or more. The amount accumulated, summarized by months in table 20, varies TABLE 20. GRIT CHAMBER, ACCUMULATION OF SCUM. Pounds Per Million Gallons. Date 8 a.m. to 11 p.m. | 11 p.m. to 8 a.m. | 8 a.m. to 8 a.m. | Remarks 1912 Dec. 1913 Jan. . Feb.. Mar. Apr. . May. June. July. Aug.. Oct.. Nov. , Dec. 1914 Jan. . Feb.. Mar. Apr. . May. June. 163 5 12 240 885 1490 1730 1430 256 28 122 71 26 32 196 400 490 416 108 6 553 633 464 303 34 47 83 111 5 12 162 625 1060 1260 1050 198 18 122 71 12 days 9 days 21 days 57 considerably, but in general is much higher in winter than at other seasons of the year. The variations in temperature of the sewage and air in part cause this. The variation in amount of killing, in velocity of flow through the grit chamber occasioned by deposits of detritus, and in the care with which the grease skimming basins are operated at the individual plants all affect the formation of scum to a certain extent. Some of these factors are seasonal, while others are local. The greater part of the scum collects during the daytime. This matter is discussed at length in Chapter XI V. Occasional analyses of the scum (table 21) show a very high percentage of volatile matter, and ether soluble material. The nitro- gen content is coriiparatively low. Based on the average content of ether soluble matter in the dry residue and on the percentage of moisture, about 15 per cent, of the weight of wet scum accumulated represents pure fat. TABLE 21. GRIT CHAMBER AT CENTER AVE. TESTING STATION. Analyses of Sciim. Date Specific Gravity- Percent Moisture Det Basis — Pbbcbntage , Nitrogen Volatile Matter Fixed Matter Ether Soluble Nov. Deo. 1912 15 .... 0.74 84.1 ' 2.64 16 . .. .... 0.73 81.0 62.9 2.56 27 .... 0.98 1.03 29 1.01 72.7 73.4 1.35 4 .... 0.99 1.04 13 .... 0.99 87.4 1.98 17....... .... 0.97 71.1 18 .... 0.99 74.3 19 .... 0.97 70.7 .... 20 .... 0.99 76.7 21 .... 0.97 65.0 22 . ... 0.98 81.8 73.0 23 .... 0.98 91 90 96 90 91 1913 Feb." 26 0.97 83.8 1.68 8.1 9.4 61.3 60.3 66.6 57.4 62.6 65.2 68.6 62.3* 66.8 65.7 58.1 49.4 56.5 58.8 Average 0.94 75.6 1:75 92.1 7.9 65.6 " With acidification 69 percent ether soluble. 58 CHAPTER Vn. PLAIN SEDIMENTATION IN DORTMUND TANKS. (Tanks C and D.) GENERAL. Two tanks of the Dortmund type were run as plain sedimentation tanks. Tank D was operated from the start un- til July 7, 1913, as a plain sedimentation tank. After that date, it was principally used for chemical precipitatioh. Tank C was started on June 24, 1913. Both tanks are similar in construction and method of operation, sewage rising from a central pipe some distance above the bottom of the tank to the effluent riiig near the periphery (see Fig. 7). The solid matter settles to the bottom of the tank and is removed, at intervals. The capacity of Tank D for settling above the bottom of the inlet pipe is about 6120 gal., and for sludge below the inlet approxi- mately 980 gal. As originally operated, the influent pipe in Tank G terminated at 3 ft. 6 in. above the bottom of the tank giving a sludge capacity of about 156 gal. and a settling volume of approximately 1590 gal. On August 15, 1913, a conical distributor was added, the influent pipe being shortened to a point 4 ft* 8 in. above the bottom, increasing the sludge capacity to 293 gal. and reducing the settling capacity to 1453 gal. The operating schedules of both tanks and the theoretical velocities of flow are given in tables 22 and 23. TABLE 22. OPERATING SCHEDULE FOR DORTMUND TANK C. From To Rate Gallons Daily Deten- tion Period Hour Mean Upward Velocity Ft. per Hour Mm.per Second Remarks June 24, 1913 Aug. 15, 1913 18,200 2.1 1.7 0.146 Aug. 15, 1913 Dei. 1,1913 18,200 1.9 2.3 0.198 Dec. 1,1913 , Jan. 5,1914 34,800 1.0 4.5 0.387 Jan. 5, 1914 Feb. 9, 1914 Used for chemical precipitation. Feb. 9,1914 May 1,1914 8,800 4.0 1.1 0.095 May 1,1914 June 1,1914 12,000 2.9 1.5 0.129 June 1, 1914 July 1, 1914 12,000 2.9 1.5 0.129 Using screened sewage. 59 TABLE 23. OPERATING SCHEDULE FOR DORTMUND TANK D. Mean Upward Rate Deten- Velocity Fhom To tion Period DaUy Ft. per Mm. per Hours Hour Second Sept. 16, 1912 Mar. 1,1913 36,400 4.0 2.6 0.224 Mar. 1, 1913 July 7,1913 24,200 6.0. 1.7 0.146 July 7,1913 Jan. 5, 1914 Used for chemical precipitation. Jan. 5,1914 Feb. 7,1914 14,600 10.0 1.0 0.086 Feb. 7,1914 July 1, 1914 Used tor chemical precipitation. ANALYTICAL RESULTS. Monthly averages of the composi- tion of the tank effluents for the day, night and 24 hr. samples are shown in tables 24, 25 and 26. 60 o Q O CM g O SO I 1^ o iS !2 ^ o I |1 o !^) ^<5 s ■ I P-i 02 • O M Iz; oooooo ^ ■^ CO CO CO CO o o o o o o 43 -*:> -ta +» •+3 -ta 05 .-I «I(N (NtH(N(N ooo^■^op eo(N (Me0t~-*COlN Cfl (N i-H i-H T-H t-H CO i-HlO -"SH 00 O lOCO'^.-lOO CD lO (M (M CO (N (N (M C« ffl>OTj 00 CO O ■^ W3 Cfl 00 < ■n H t- M ,- ^ ^ <1 T3 p ^ Q 2 iz; ?? P m g o F-l cc « s ■S3 ^ S3 1— 1 Hi ^ d o O •43 HH (1 H s . H ^ W CQ -n P S ^ S Q QQ ;:^ o •K (i( P Iz; S3 H £ o -r) 02 0) w d ^ P. HH Ph ^ ta -g ^ Screen ings P.P.M. lO-«:HCO(M«)CCc5?H»0^ ^ i w w ■3 ^ to 1 " 02 O3i-l00G0W5t^iCt-*OSiO t~ S3 3^ -J ■a fe II 02 ^H 1— (»— 1 T—i § on" 00 an— K 1=1 CO § sli-i cDoo-^io cqcocoiooo ^ m ■ 02 Eh 1 li 1 S3 '^ p. n 02 PL, to (NO(N(N(MCDC^00(NO OOiOCqCSOIr-CD^O i-H tH t-I ,-( 1-1 (M § Ed < P ^"1 -3 -s 00t^t>l>-00CDiO0000Q0 00 i Oi-HI^-OSt^OsCOOiOO l> CO CO CO t^ lO'iO I> l> 00 § d O{N0i00CD0:u:>00OI> 1— 1 1— 1 T— 1 Oi 1^^ T3 S3 If gpH 02 lOCOi-HCDlCCCOOlM^OS OOiOsi>.i-iCOCOI>Ol> 1—i 1—1 1—1 N 1—1 1—1 1—1 lOCOO.-l(NOO(MiOOOO t^O"*OC0J>-^i- <1 .5- ■73 d 3 02 bO d 1 -d" to _d fl « 3 S * «"? -^^ >>« a d-^ t- " 2 2 6! d S3-^-^i. og&il a x> CI C ^ Pmoo-I o 66 REDUCTION IN OEGANIC NITROGEN, FREE AMMONL\ AND OXYGEN CONSUMED. Table 30 shows the reduction in organic nitrogen, free ammonia and oxygen consumed for the day sewage for both tanks. During the winter and early spring, the reduction in organic nitrogen and oxygen consumed was consider- ably less than in suspended matter, because of the presence of solu- ble wastes. The free ammonia showed a slight increase. With the return of warm weather, an increase in the percentage reduction of organic nitrogen and oxygen consumed approaching the removal obtained on suspended matter was noted. At the same time a marked , increase in free ammonia was noted, as well as a decrease in nitrites and nitrates. Under the influence of rising temperature, oxidation of the organic matter in the sewage was apparently stimulated at the expense of the oxygen contained in the nitrites and nitrates, particularly in Tank D. The effect was not marked in Tank C, al- though a substantial reduction in oxygen consumed and organic nitrogen occurred, accompanied by a corresponding increase in free ammonia. SLUDGE AND SCUM. Scum was consistently present on the surface of both tanks from the start, forming usually within 24 lir. after cleaning and often to a considerable thickness as time elapsed. During cold months it formed more slowly than in warm weather. Prior to the installation of scum boards, considerable scum escaped in the effluent, but thereafter much less. During May and July, 1914, Tank C was run on the effluent from the rotary screen during the daytime with a detention period of three hours, and during June with the same detention period using the effluent from the grit chamber. A very slight scum accu- mulated during the last few days of the runs on screened sewage, but in June a heavy coating was present almost continually. The relative rates of scum formation of 0.5 eu. yds, per mil. gal. in May and 3.1 cu. yd. in June point to the value of preliminary fine screen- ing as a possible remedy for excessive scum formation. The light fibrous material removed by the screen is largely responsible for the heavy mat of scum. During the hot summer weather, the surface of the scum often baked hard in a thin skin, which, on removal, frequently revealed large colonies of maggots. The scum thus affords a very favorable breeding ground for flies, as well as the sludge drying on the sludge beds. Ordtaarily the scum had no objectionable odor, except when stirred or agitated. Owing to the necessity of skimming off the 67 m -I Q 13 < O M I izi o o p P-i H =g li I if T3 |2 to CO l> !>. I> t- N (N tH T-( T-H T-H oooooo •^ Tt< CD to CD CO 05 00 IC T-H 00 Tt< (M f5 M ■* ■* "3 * * * * * OOOCOOOO t-t »-j lO o 00 OS-^ QOCO (N eq (N T-t rH T-H rH a 5 co>0(M coeog H IM(M(NffqimTH (Nt~l^O00-* cq i-H CO »o lo CO COffO (N CM (N OS 05 05 O ' ■^ W) CO CO CO CO ^ llss°^ So 1—1 S5SSS.gg5S s coiO'ii mcoN ■* >* lO t~ 00 00 ' T— 1 ?-H 1— ) 1— ) tH T— 1 s °MN«^N ^ cocsooint-co IO"3W3"5COt^ s O 00O*H N l> ^«NCNC^(M S?3S?3^S ?3 T-l -^ CO 05 CD ds t~t>l>CO00 00 f: August September. . . . October. ...... November December 1 68 w QQ C3 ■i^ ^ «^ d H rt 1=1 M o B ^1 p' a. 1 g f2 rt ^ o ■^ « 6 y P a CO 1-1 3 < o 1- 'A r/j ^^ 13 Iz;- ^ o So H Tl <^ 3 H no t? g s P 1 oa s ■S 1 '<< < ■_J iPLi t3 00 ■>! OQ fl 13 3 OS _3 I P oqO O V C3 01 fo > > >\' ^ &„ o o o o o- I a s i s £i3 g-s gi3 g-d g -a a'fl« ci3,a3ci3« rt^ fl _ eas n ca H ee g oa: g; es -p-oj- --3-»--3«3« 3 43 oaO OQOoaOoQO qq O COCDCOCDo ••* 00 -OS . . -O ■■* -00 • ■ • >-( ■ (N • C« (N (N IN (N IN .-i i-i T-i T-i rt' i-i ,-( OOOOOOOOOOOOO •5O00 -ooi •00 •d INUSINININ^'^IN cococccocococcco •M-^TtllC ■ CO CO CO CO JV.-I50 IN'* to • ca.-i^o ■ CO CO t^ CO ■,-ICO .i>!cd ■CO ■lOCO ■coco' •T(<,-l ■"5C» • o ■-*■ OOlNOOOOCOCiOt^ ■ -O • • ■' 1-i ■ i>! .■ -^ ■OSC^I -t^ -1-1 -OS ws ■ 00 -si -co '00 • 1-1 00 •i-lO -co -1-1 • ■■* ■ 00 CO • r-' -1-1 • -co 1-1 rH IN 1-1 OOINOOOOC0050t~ ■^O5^HCflC0C^C0i-i l-l ' ■ OS t^ "^ 05 • ■* CO 15 00 00 IN iH -OOOS OCO Cq' CO -^ • ■*' IC ■*' IN • OS Cfl ■ t^ -1-1 ■ OS lO ■OO"**! -co -00 • F-HOO INt~>OOSO(N'*COTtl l-l IN (N(N 1-llN OS ^*5 > cj o ^ eOi-it^O(NU500-«:t 4 (2 §^s s, ^ fJ9 o iA ^ iz; O •< a H n -.a n w ^ SS «■ 6 C 73 |3 03 K ■< s s « . i|-ils S||£W -B f^ aa , iS f^w ■Has S «> g <^ 1 u ^ 1 CO p 1^^ !a S M B U a J pa ^ ^-7- !^ £) 02 . o S ^ S C3 S " g H g 3 g CO H • a Iz; -o « 5 CD s ■ a ■a "O 00 CO CO CO ■I r-i r-i M (N CO CO CO CO (M* N Csi N CO CO CO m CO CO CO CO CO ifs ■ oo Cg(Mi-Hi-Tt01Wi-lr-(0 ^mn'mcococo ■NNCOOOiMOrHOO-tfTHOW •USCOOOOCOOOCOIOMOOCO ■ O® 00t-"3«0 ■ O) 00 05 iC T}i -^ CO N t» CO Tf CO OS O) t* CO lO t> CO . .-icoiH'^'i>i>co-*Ttcoioi>co iHeOrH'*t-t*cO'^'-^b-eo'^co . 03 »0 »0 05 b- OS ■ O lO O ■* OS --I (M i-HOO CD CO CD •ei|rHrHCOCSl(NCONI>'#C0(N .rt^COOOXt* ! (O CO t* 04 M N 3 2 U (1) (DO} O' u o o o. o -(10»010»0»0 o oooooooooooooo r-i '^' ■^ I}* Tf T*I ■^' ■*' Til ■^ CO CO CO CO CO ■OSOiOOO -co ■»OiOCO"3- "lO ■ OJ Oi OS t- Tt*Nb-'*iflcMot-a)Oo "-i jiOCodoOSOOtHOS'-iTtiiOO oioocadiM'M»ocqNcocoob-dw'<*oob-"*Oicoi-*coco.H«os II i I "§ |i|g ■ rH •00 • "^ »0 CD »0 lO tH • occ ■05CP • t^ T-H • ^ ^ Ttl o g 00 02 I •0000 -ON 1-H • .1-1 • 1> o ■ i> ui o • • cc • qOt-1 --^ ICO OSCDT-li-ie0«DTHrH00O5Oi 72 Tank C, with all results reduced to a standard moisture content. For comparison sludge measurements are also given. The sludge flowing from the tanks varied in color from a dirty brownish or greenish gray to almost black, that from Tank D fre- quently giving off a strong odor of hydrogen sulphide. This was not noticed in Tank C, possibly because the small sludge storage space necessitated more frequent cleaning, thus minimizing the de- velopment of septic action. Considerable amounts of gas were given off during the winter by Tank D. Some difficulty occurred in running the sludge from the tanks, particularly during the winter of 1912-1913, when on several occa- sions it became almost impossible to clean Tank D. After a small amount of sludge was withdrawn, clear sewage would break through. If shut down until the sludge gathered about the sludge pipe inlet. TABLE 35. PLAIN SEDIMENTATION IN OLD DORTMUND TANK (TANK D). Analyses of Bottom Sludge and Top Scum. Date Specific Gravity Per Cent Moisture CALCnLATED TO DrT WEIGHT — PERCENTAGE Nitrogen Volatile Matter Fixed Matter Ether Soluble 1912 Oct. 7*. 25*. Nov. 9*. 22*. Dec. 4.. 13.. 24.. 1913 Jan. 17 . Feb. 10. 25. Apr. 4 . May 27. June 11. BOTTOM SLUDGE 1.01* 1.00* .00* .03* .02 ,02 ,02 1.03 1.03 1.00* 1.00* 1.03 1.02 98.9* 91.8* 95.8* 92.1* 93.1 94.6 90.8 89.7 91.6 89.1 92.0 92'8 2.24 2.64 2.32 3.04 3.44 4.90 3.36 3.36 1.68 3.04 2.56 2.56 2.32 80 70 77 78 78 79 76 76 78 74 74 75 31 20 30 23 22 22 21 24 24 22 26 26 25 9.7 7.8 8.6 8.8 10.0 7.3 9.5 8.0 9.8 9.3 7.7 8.8 6.4 Average. 1.02 91.7 76 TOP SCUM 1912 Oct. 25 1.02 1.01 1.02 1.02 i^os 1.01 1.02, 1.02 1.05 1.03 1.02 1.01 93.0 81,3 85.0 84.7 87.2 87.7 90.1 84,3 81.9 79.6 80.6 81.0 81.0 3.36 3.84 3.52 i!44 2.16 2.64 1.76 2.64 2.96 2.16 2.16 75 • 74 78 72 77 75 76 74 75 75 73 73 25 26 22 28 23 25 24 26 25 25 27 27 Nov. 22 . . . 10.4 9,0 9.7 Dec. 3 24 1913 Jan. 17 Feb. 10 11.6 9.2 8.6 7.4 11.4 7.8 7.2 ■ 9.2 26 Mar. 27 Apr. 4 . . . May 7 22 19 '. Average 1.02 84.5 2.60 75 25 9.1 Note: • Samples from sludge filter omitted from average. Other sludge samples from tank. 73 flow would again resume. Twice this difficulty was overcome by sus- pending a metal disc about three feet in diameter over the surface of the . sludge, which may have prevented vortex action. Differ- ences in the character of the sludge may have caused the variations noted. However, sludge was readily removed when the disc was used. The low specific gravity of the sludge, combined with the stir- ring and uplifting tendency of the gas formed, may have prevented free flow toward the sludge outlet, or the friction against the sides of the tank and hopper may have caused the sludge to hang, form- ing a cone-shaped depression in the center of the sludge mass through which the overlying sewagp finally broke. Stirring was effective when the sludge had become particularly compact. Analyses of sludge. and scum for Tank D (table 35) and for Tank C (table 36) show the composition of the sludges and scura.s TABLE 36. PLAIN SEDIMENTATION IN DORTMUND TANK (TANK C). Analyses of Bottom Sludge and Top Soum. Date Specific Gravity Per Cent Moisture Calculated to Dry Weight — Percentage Nitrogen Volatile Matter Fixed lyiatter Ether Soluble, 1913 July 9 . 18. Aug. 2 . 16. 22. 28. Sept. 22 . Oct. 3. 17. Nov. 7. 21. 1914 Mar. 20. 1.02 1.01 1.01 0.99 1.01 1.01 1.03 BOTTOM SLUDGE 1913 July 18 . . 1.02 1.02 1.02 1.05 i!62 1.01 1.02 1.01 1.02 1.02 1.02 1.03 1.01 1.01 89.5 92.7 91.3 86.8 92.5 89.9 91.3 91.2 90.2 90.0 87.2 91.0 92.5 91.7 94.2 2.56 2.80 2.44 1.84 2.72 2.56 2.56 2.96 2.88 2.88 3.04 2:S6 69 74 69 62 177 67 71 73 81 78 71 73 67 31 26 31 38 23 33 29 27 19 22 29 27 32 7.1 Aug. 2 6.2 18 7.9 22 5.5 28 3.3 Sept. 22 . 7.6 Oct. 3 9.0 17 7.9 Nov. 7 9.1 21 8.2 Dec. 16 7.3 1914 Mar. 20. i6.8 27 17.4 27 top of sludge 1 13.5 botto m of sludge Average 1.02 90.6 2.65 72 28 8.1 TOP SCUM 1.02 81.2 79.8 84.4 84.4 82.6 83.6 83.6 83.5 83.7 86.3 83.4 84.4 2.56 2.64 2,88 2.40 2.56 •3.12 3.04 72 70 62 69 68 71 68 72 71 76 77 28 30 38 31 32 29 32 28 29 24 23 30 7.4 7.7 7.2 6.9 7.3 3.5 7.5 9.2 9.4 8.3 7.6 10.5 7.7 74 to be almost identical, except for the lower moisture content of the scums averaging 84 per cent, as compared with 92 per cent, for sludge in Tank D and 85 per cent, against 91 per cent, for Tank C. The percentage of volatile matter in the sludge and scum from both tanks is high, little difference being noted between the sludge and scum from the same tank. The nitrogen content averages nearly 3 per cent., whereas the ether soluble material averages 8 to 8.5 per cent. The fat content of the sludges was determined by extracting with ether without acidifying. "When the sample is first acidified, considerably higher results are obtained, probably due to the break- ing down or "cracking" of the soap fats which are not recorded by the simple ether extract. For instance, 2 samples of bottom sludge, showing percentages of 7.4 and 10.0 with simple ether extraction, gave values of 10.0 and 25.6 when first acidified. ACTUAL PEEIOD OF FLOW. In the body of this report, all figures have been based on the nominal period of flow, assuming com- plete and uniform displacement, a condition only approximated in practice. Several attempts were made to measure the actual deten- 550 500 450 .^400 t t r so ^^50 ZOO 1 ^—- / \ ■ / ^ ^ ^^ j ^ N 1 . / 1^ , / ^ > M>, 777^/ /P/Aa '/7/^- r I- > • 1 A /. 5- 3 4 S- 6 V z 5" e /i K- A /> L IS /i. W /i ■y /ao T/merMbu^s. Fig. 12. Flow Period in Dortmund Tanl< (C). tion period but the unusual character of the sewage interfered. Dyes were tried with indifferent success, owing to the reducing action of the sewage on the coloring matter and the difficulty of getting a distinct trace of color in the highly colored effluent. Of the chem- 75 icals ordinarily used, the quantity l*equired to produce an appreci- able effect was so large as to be impracticable in most cases. A fairly successful test of Tank C was, however, made while running on a two-hour schedule, before the conical distributor was added to the influent pipe. The alkalinity of the sewage was in- creased on a Sunday by adding sodium carbonate, samples being taken at 5-min. intervals for. 2 hr. and every 10 min. thereafter for an additional hour. The results (Fig. 12) indicate considerable vari- ation in rate of flow, a portion of the sewage passing through very rapidly, the peak in the curve being reached 35 min. after application began. A portion flows through very slowly, the' alkalinity being high at the end of 3 hr. Diffusion of the chemical may have had an influence. Although sampling was not continued until normal alka- linity was restored, an average period of flow was found less than the, theoretical. 76 CHAPTER VIII. EMSCHER TANK. GENEEAL. The distinguishing feature of the Imhoff or Eiti- scher tank (tank E) is the provision made for the retention and digestion of the sludge in a chamber separate from that through which the sewage flows, so arranged that the gases of digestion pass off through a separate vent without contact with the incoming sewage. The construction and details of the original and remodeled tanks have already been outlined. (Fig. 8.) The operating schedule , is shown in table 37. TABLE 37. OPERATING SCHEDULE OF EMSCHER TANK (TANK E). Date Rate Gal. Daily Period of Flow Hrs. VrTjOCITT From To Ft. per Hr. Mm. per Sec. Down 1 Up 1 Down Up Sept. 16, 1912 Nov. 2, 1912 Mar. 1, 1913 May 15, 1913 Oct. 1, 1913 Feb. 10, 1914 VERTICAL RADIAL FLOW, ORIGINAL Nov. 2, 1912 Mar. 1, 1913 May 15, 1913 Oct. 1, 1913 Feb. 10, 1914 Mar. 9, 1914 27,400 2.0 8.7 3.8 0.74 18,200 3.0 5.8 2.5 0.49 13,700 4.0 4.4 1.9 0.37 27,400 2.0 8.7 3.8 0.74 36,400 1.5 11.6 5.0 0.99 27,400 2.0 8.7 3.8 0.74 0.32 0.21 0.16 0.32 0.44 0.32 Mar. 19, 1914 June 1, 1914 HORIZONTAL FLOW, REMODELLED June 1, 1914 15,200 1.9 9.2* ... Sept. 2,1914 10,000 2.9 6.0* 0.79* .... 0.52* .... * Horizontal velocity. ANALYTICAL RESULTS. Monthly averages showing character of the effluent are given in tables 38, 40 and 41. the 77 iz; "iz;- W CO O UJ -« _l [x. § H 1- ^ H 1-1 M^l t=H ' w fe o m H CO bn l-I ■ m lO lO CO M Tji ^ tH (M ■'iH 00 00 (M »0 ^ t> CO O CD Oi Oi t^ 1^^ CD C» C^ (^ CO t^ ci C^ r/) CO CO (M (N (M (M (M (N (M CO (M IN cq >^ CO CO C35 00 -^ lO W5 CO 1-1 TtH t^ o 00 1^ CO cq eq 1-1 T-i ,-1 1-1 r-1 ,-1 ,-1 ,-i 1—1 . cq 1— t T-H 1-1 P4 00 tH 1—1 o <^ CO CO 'cH t~ 1-1 t> O 03 l> o CO CO CD . CO t- (N (M (M 1-1 T-H 1-1 i-( 1-1 1—1 cq 1—1 I— 1 (M >^ <^ -o 1^2 IC lO J>. O -1:)^ O^ CO »0 f£> cq ^. 00 ^ 'ii (MCQN JhoS^N^ (M .CO COC§««-* CO^COTt* CO (N o o o t~ Ci Oi t^ lO O CDIO o»o O 05 o S o o irieo 1913 January. . . February. . 1 -^CD 1—1 r-l 1- ■s i ft CO Si S3 .o > 1 1 CO 1— I i si. 1-1 HS 78 3 EQ 5 g. b cc M & M COGOOOOOOOOOO CflCN^HT-Hi-lCOCOCCCOCOiOuaiO ooooo (NNtNOOO OOOOOOOOOOiOiCiO CO CO •'J^ •^' '^ n' c'^C0i-IC0r-(05C0C000i-l lO CO O g »0 CD CO !> I> t^ IXOCOCOt^cOcOt^OOOOCOiO" CO CO o t^ lO i-i lo t^ o CO "^ lO 05 osop CN W Cq W Cfl (M Cfl *H CM (N i-H CS» r-* — — ' t* "-iOi-l^»Ot^CDNI>C0 (MOOCD^CflCOlOi-cOOO 00 CD 00 * 05 CD ^o^^oo^*ocDQOl>o T-l rH t^ 1-H tH T-H O CO epos 00^-CO COtDUSiHMO CDCDCDU5COU3U3U3U3U3LOU510 ■"HCO o o CD o> -. oi n o o o 79 1 4 H -a. Z 02 O 111 ffi o iz; pq 'a o o OS fi] fi( musrooiosooooooooooooo OOOOOOOOOOU3UMO e<3 M ■"*< ■*' ■*■ Ci) im' (m' cq N ^ r^ rA NrHr-l CQ Ca CO i> -^ rH CO UDTHC0"*CDU3TfiMC0T-lN(N(N i>CSI00OiOiCCC03C> ii ooooo lOCOCO IM(M(N ooo 0:> OS O) CD CO CO lO O O 03 O^ 0> 03 O) 03 .-I Im' * > w OQiniM'St^CO . . . . C9 ■-! IN >ff "H 1-1 • • ■ • to O Cfl m TjH 1-H 00 t^ CO CO OOCOOO-TJ05"5"5 10"3-* o a -3 lomco cocot^"*co(N T-( GO 00 tH t>- 00 i-H OS OS '^'=> (^PhS g , a 3 oa H 'fa ■a a & 4 03 PP § 3 t3 5, m o o p Q m Pi a O » a » EQ 00 lO lO U3mCi03050000QOOOOOOOO OOOOO (N(N(NOOO OOO OO OO OO OO OO ICIO IC (m' M CO CC PO ■^' -^ ■^" (m" CnI (N N . O CD T* ,-( op 1-^ i-( t^ TtH op 03 lO-i^lO -^ -^ lO Ttl "^ Tt* -^ 1^ -^ CO "^ •"*' 1^ t^CO(Ni— IOPeOt^i-(03IMOO.-l O0plO*C-^0000t^l>« lO IC »0 O »0 UD lO CO «D t^ O 03 CD » (M rt ■* IM (M ^(N (N O3(M00 00 lO ^ CNOOlOOOtNCDOcDi-i-^T-fOOCD WOOCDOOOPt*t^TtHlOOPlO»0-* C^T-1i— It— IrHi— 1f-1i— lr-HT-ti— It— It— I T-H>IO Til CO t^ coco en T— IOPOIMt— It— lOSOCDTfcD^CD OOTtllMT(lO-*C<10T-l'*03000 (MCNIMlNCQIMlMirqCniSlT-KNT-l «>00(M"3JCO2>O(Mt-M t^C0C0-S00OC.»OOOsOit^CDCOOOCCOO OSCO-x^Ht^iOOr-IOSOSi-HOSi-lOl cococo(Neococoo»c^co(Mecc- CO (NO OS "^ "^ coco lO lr^(DCDlOCOOCvlOSt-i-ti-li-lcO '-HTHlf5t^I>.C lO'^-^CO'^TpTt1CO-<^Tt, H a.g S fe a o o T-H CD 85 03 3 «• i^&tl OS >»"^-^ T-t tjOS 1-1 03 , CO o •3^ S'S^"" 81 REDUCTION OP SUSPENDED MATTER. Tables 39, 40 and 41 show the percentage reduction in suspended matter for the day, night, and 24-hr. samples by months. In the day and 24-hr. averages Sunday results have been excluded, owing to the greatly decreased strength of the sewage. The average results by periods of flow are given in table 42. , TABLE 42. REDUCTION IN SUSPENDED MATTER BY PERIODS OF FLOW. Deten- ■ tion Period Hours Mean Upward Velocity Ft. per Hours Suspended Mattbb — Pabts pee Million Pee Cent Reduction Influent Effluent Total Vol. Fixed Total Vol. Fixed Total Vol. Fixed DAY SEWAGE 4.0 3.0 2.0 1.5 1.9 586 446 140 283 214 69 52 52 2.5 638 487 151 316 243 73 50 50 3.8 645 418 127 267 199 68 51 52 5.0 521 417 104 246 192 54 53 54 4.0 3.0 2.0 1.5 1.9 2.9 9.2t 6. Of 85 100 Horizontal Plow I ... I 60 I ... 51 29 49 51 52 47 48 Horizontal Flow 1.9 9.2t 400 158 61 2.9 6. Of 365 101 72 NIGHT SEWAGE 1.9 154 125 52 174 123 51 2 2 2.5 177 101 ,53 153 110 43 1 9* 3.8 137 95 42 104 74 30 24 •22 5.0 135 99 36 88 62 26 35 39 2 19 28 28 4.0 3.0 2.0 1.5 1.9 2.9 24 HOUR SEWAGE 1.9 427 319 108 235 177 58 45 45 2.5 533 405 128 285 217 68 47 ' 47 3.8 435 336 92 228 174 54 48 48 5.0 379 299 80 191 148 43 50 51 9.2t 6.0t 293 266 Horizontal Flow I ••• I 124 I ... 82 58 46 47 45 46 * Denotes increase, t Horizontal velocity. ' The efficiency of the Emscher tank with different vertical veloci- ties, during the operation of the tank on the radial flow basis, varied much less than did that of the Dortmund tanks. During the entire period of operation on the 3-hr. and 4-hr. periods, the process of ripening was going on in the digestion chamber, causing more or less disturbance in the operation of the tank. Scum baffles for the 82 effluent nipples were not installed then or during the greater part of the period during which the tank was operating on a 2-hr. deten- tion period. During September, 1913, the sludge level rose above the level of the slots. When the period was changed to a l^-hr. basis, individual scum baffles were provided for the effluent nipples, retaining considerable light scum which formed on the surface of the settling chamber. With the change to horizontal flow, considera- bly higher efficiencies were recorded. REDUCTION OP ORGANIC NITROGEN, FREE AMMONIA AND OXYGEN CONSUMED. Table 43 shows the reduction in or- ganic nitrogen, free ammonia and oxygen consumed for the day sewage, for 1913. The decrease in organic nitrogen, while apprecii able, was considerably less than in suspended matter, because of the large amount of organic matter present in solution. The free ammo- nia consistently increased, accompanied by a decrease in nitrites and nitrates, indicating a slight oxidation of the organic nitrogenous TABLE 43. SEDIMENTATION IN EMSCHER TANK (TANK E). Reduction in Organic Nitrogen, Free Ammonia and Oxygen Consumed in Day Sewage Parts per Million. Per Cent Reduc- tion Period of Flow Hr. Date iNFLUENTf Efpltjent 1913 Org. Nit. Free Amm. Oxy. Cons. Org. Nit. Free Amm. Oxy. Cons. Org. Nit. Free Amm. Oxy. Cons. Jan Feb "... Mar Apr May 1 to 15; 16 to 31 June July Aug Sept Oct Nov Dec 96 91 71 70 83 78 81 71 74 76 69 86 89 24 25 19 20 23 21 21 21 22 21 22 24 24 322 317 267 250 268 250 264 240 228 250 251 282 287 79 79 57 55 50 56 55 53 45 50 48 60 72 30 28 24 26 40 33 40 30 42 37 32 30 32 238 237 198 180 147 150 155 143 118 149 171 203 185 18 13 20 21 40 28 32 25 41 34 30 30 19 25* 12* 26* 30* 74* 57* 91* 43* 104* 76*. 45* 25* 33* 26 25 26 28 45 40 41 40 48 40 32 ■ 28 36 3.0 3.0 4.0 4.0 4.0 2.0 2.0 2.0 2.0 2.0 1.5 1.5 1.5 Av. ...... . 80 1 24 268 59 32 178 26 33* 34 * Denotes increase, t Crude sewage. matter. With the approach of warm weather in May, a sharp in- crease in the reduction of organic nitrogen was noted, together with an increase in the amount of free ammonia. The nitrites and nitrates were also lower. These changes occurred almost simultaneously, 83 apparently following increasing temperature, with the resultant in- crease in bacterial action and increased oxidation of organic wastes. The oxygen consumed was decreased less than for the suspended matter, owing to the presence of soluble organic matter, altho in the late spring and summer the percentage reduction approached that obtained on the- suspended matter. Apparently the same fac- tors influencing the reduction of organic nitrogen were at work here also. SLUDGE CHAMBEE. The Emscher tank is about 17 ft. deep from the flow line to the bottom of the hopper. Seven days after th& tank was started, the evolution of gas became noticeable and the gas funnel had plugged to a depth of about 5 ft. with a brownish floating sludge or scum of very offensive odor. This scum was broken up daily to liberate the accumulation of gas underneath, and was frequently removed throughout the entire winter, and even up to the middle of April, 1913, as it formed quickly. At one time the accumulation reached a depth of 8 ft. The production of gas was practically continuous from the start, but the clogging of the gas vent, by the vigorous scum production, retarded the escape of gas at times- and occasionally caused ebullition through the sludge ports. On one occasion, the pressure was so great beneath the plug of scum that an attempt to break it, up caused the gas vent to over- flow into the settling compartment. Odors at times were very noticeable, particularly of hydrogen sulphide. After the first of May, 1913, however, little or no trouble was experienced, the ripening of the tank having apparently been com- pleted. Only a thin mat of light floating material collected during the summer of 1913, altho ebullition of gas was continuous and vig- orous. The odor of HgS was noted occasionally, although usually only on very close examination. Slight white deposits, presumably sulphur, were noted about the effluent pipes. During the summer a thin greasy scum accumulated in the inlet portion of the settling chamber, but this seldom exceeded a depth of one inch and gave no trouble in operating the tank. With the approach of cold weather, the scum reappeared in the gas funnel, though not to the extent noted during the first few months of operation. With the remodel- ling of the tank scum has continued to accumulate in the gas vents to a small extent. Owing to the excessive attention required to keep the gas vent clear during the first few months of operation, this tank was not regarded as favorably at first as the Dortmund tank. But as the tank became thoroughly ripened, the difficulties of operation largely 84 ceased, and very favorable results were^ obtained. The excessive scum formation is apparently incidental to the ripening of the tank, although occurring less markedly at other times. Ample area must be provided in the gas vents for the escape of the gases of digestion, far more than for domestic sewage. The original proportion was 8.8 per cent, and as remodeled 34. TABLE 44. SEDIMENTATION IN EMSCHER TANK (TANK B). Sludge and Scum Accumulation in Cubic Yards Per Million Gallons. Date Cubic Yards Feb Million Gallons Sludge Since Last Meas- urement Scum Since Last Cleaning Since Start Sludge Scum Sludge and Scum Deten- tion Period Hours Mean Upward Vel. ft. per hr Cu. Yds. Sludge Re- moved 1912 Oct. 25. Nov. 7. 16. 22. Deo. 12. 1913 Jan.. 11. Feb. 11. 22. Apr. 4; 18. 23. June 11. 24. 18. Aug. 19. Sept. 5. 27. 30. Oct. 14. 21. Nov. 6. 13. 18. ■20. 26. Deo. 10. 12. 17. 1914 Jan. 12. 16. 19. 21. 28. Feb. 6. 11. 19. 28. Mar. 9. Mar. .20. 27. Apr. 4. 13. 16. May 1 . 13. 26. June 1 . 13.3 13.4 10.3 4.3 8.8 6.3 0.6 4.3 4.3 8.5 9!3 8.8 7.9 11.2* 17.4 3.2 13.8* 8.9* 16.0 '3.6 2.9 i!6 1.4 S.2 b'.i 0.0 0.0 0.0 0.0 6!i 0.4 0.6 0.4 5.0 1.0 6!4 13.3 3.4 6.0 1.1 3.2 3.9 3.6 3.7 3.8 4.1 i.& 4.8 4.9 5.3 5.9 5.9 6.3 6.3 5.0 4!6 5 3.1 3.2 0.4 3.5 2.8 1.4 ■0.4 1.3 1.3 1.3 1.3 1.3 7.0 2.8 6.4 1.3 7.7 0.0 1.4 6.4 1.3 7.7 7.6 ■0.4 6.4 1.3 7.7 13.4 ... 6.6 26.6 ... 6.3 12.7 1.0 6.4 1.3 7.9 ... 6.4 14.5 1.1 6.5 1.1 March 9 to 18 Tank Remodeled (Velocities Horizontal Hereafter) 7.7 38.5 6.5 1.4 13.8 10.9 65.8 8.S 6.4 6.2 3.9 0.6 0.4 6.5 6.6 6.6 6.6 6.8 6.8 6.8 6.8 6.8 1.4 1.3 2.0 3.0 3.0 3.0 3.0 3.0 3.0 3.0 4.0 4.0 4.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 1.5 1.5 1.6 1.6 1.6 1.6 1.6 1.6 1.6 1.5 1.5 1.6 1.6 1.5 1.5 2.0 2.0 2.0 2.0 2.0 3.8 2.5 2.5 2.5 2.5 2. 2. 2. 1. 1. 1. 3.8 3.8 3.8 3.8 3.8 3.8 3.8 5.0 6.0 6.0 5.0 5.0 5.0 3.8 3.8 3.8 3.8 3.8 1.9 9.2 1.9 9.2 1.9 9.2 1.9 9.2 1.9 9.2 1.9 9.2 1.9 9.2 1.9 9.2 1.9 9.2 3.3 2!3 4.5 sis 0.2 4.9 6.1 2.8 9.6* 4.7* 10 ! 6* 10. 17.7 6.2 * Measuremen uncertain. 85 SLUDGE. Measurements of the sludge were made at montlily intervals, as a rule. The results expressed in cubic yards per million gallons are shown in table 44, with the quantities of scum from the gas funnel. The first few measurements of sludge fluctuated considerably, for on one or two occasions the sludge line was rather indefinite. Later measurements proved more consistent, the sludge apparently compacting with the ripening of the tank. The rate of accumulation during the first few months of opera- tion was very erratic. Sometimes very high rates occurred between individual measurements, and again an actual 'decrease, due prob- ably to variations in density and compactness. The results are also somewhat obscured by the varying amounts of gas-lifted scum of lower moisture content and therefore smaller volume per unit of dry matter. After the disappearance of the scum, the results proved more uniform. TABLE 45. SLXJDGE.ACCUMULATION BY PERIODS. Period Mean Cubic Yaeds per Mil. Deten- Upward Gallons tion Period Velocity Ft. per Sludge Scum Total trom. To Hours Hour Sept. 16, 1912 ' Oct. 25, 1912 2.0 3.8 13.3 3.3 16.6 Oct. 25, 1912 Feb. 11, 1913 3.0 2.5 -3.8 3.6 -0.2 Feb. 11, 1913 Apr. 23, 1913 4.0 1.9 8.8 2.4 11.2 Apr. 23, 1913 Sept. 30, 1913 2.0 3.8 5.8 0.1 5.9 Sept. 30, 1913 Jan. 28, 1914 1.5 5.0 9.7 0.8 10.5 Jan. 28, 1914 Mar. 9, 1914 2.0 3.8 7.5 1.0 8.5 Mar. 9, 1914 | June 1, Horizontal Flow 1914 I 1.9 I 9.2* 10.0 1.4 11.4 * Horizontal velocity. The rates of sludge accumulation (table 44) show a reduction in the rate of scum formation after the ripening of the sludge cham- ber. Variations iu volume may be largely traced to changes in moisture content and eonipactness of the sludge (table 46) when the rate of accumulation is reduced to a uniform moisture con- tent. Possibly with a tank of working depth, a more compact sludge would be obtained, reducing the unit rate of accumulation. In applying the results to actual conditions, it should be noted that this tank was operated at a uniform rate of flow throughout the en- tire 24 hr., whereas, the flow in the sewer fluctuates between wide limits during the day and is greatest when the sewage is strongest and deposition is most rapid. ' Design must therefore take account 86 H O M a t3 a>os • IN O 1>^ to I> •COi-H •* '.'.'.'. -a • 00 W3 Oi— 1 1-1 ■>OI>COOO ■ CD T— I T-H T— I T— I ■* ! .■ : I ^o •OSOOOINOO ■ cq lo CO 1^ 005 :?S .a IOU3 IC O lO lO hoo eflcoiot^ocoiot^iot^o O -t^T-H CO ■ cocoes •t*CDCD ■COOi-4 . COi-H ^H • oot--tx> U3 kOiC OiOiOU5ifliCI>t*l>;000 lO lO lO US lO ^ p). csi CO lo bJ o CO lo t^' »o t* g 95 I 02. H iz; o o p, A o O I ■a o '■S I .9 o I O . T3 a a O O Jo U ID o • ■ ■ . ,.o o I> ta OOOOO 'O OO ^^ "511 ^ ^ • ^ OOQO 00 ■*!«•«# OO o cgtp la 0-* ■* • oo • o • cq oo (N CO o to •O -O -IM to ■CO • Co 'Sso T-KNCOTfuSt'.'oNWO •S ^ rt ^ iM o : 00 §§^^ :§::::: Sg^ :::::::: S : : :§ '.feS; ^ t> : : : : :g :g : :^ : : : : :g :f2 :S388 ^ ':::::§ :^g ^ ,-1 . (35 • ■ (N • • CO lO .1(5 • • "5 • ; >0 o.- lO lO (NcOThwt^ONmo rH 1— 1 T-t Cq 96 approximately SJ in. wide, with 180 deg. turns at the ends, making a total distance of travel about 100 ft. The lime solution was added to the sewage at the entrance to the trough, flowing nearly the entire length, before the solution of copperas was added. Owing to the relative plevations of the main orifice box and effluent ring in the tank, it would have been impossible to construct the trough with the proper slope to give a uniform velocity throughout without ex- tensive alterations. The requisite head to overcome friction losses was obtained, however, by backing up the sewage in the orifice box. The velocity in the first half of the mixing box was, conse- quently, low enough to allow some deposition, but the general results obtained in the tank showed great improvement. In an actual plant with better mechanical appliances, greater, efficiency in mixing could be obtained. CHEMICALS. For convenience in handling, a high grade of hydrated lime packed in 40-lb. bags was used. For a short time, quicklime of good quality was tried, but the labor of slaking, as well as the more rapid deterioration in a damp atmosphere, caused a return to the hydrated lime The lime solution was applied to the sewage at a rate from 20 to 40 gal. per hr. (cf. table 54) regardless of the amount of chemical used, variations in the rate of applica- tion being met by changing the strength of the solution. Although the lime used was advertised, as of exceptional quality, considerable impurities were found, as shown in table 52. TABLE 52. ANALYSES OF LIME AS DELIVERED. Date Percentage of Percentage as Remarks 1913 CaO Ca (0H)2 July 17 48.8 64.5 Hydrated lime 21 46.8 61.8 Hydrated lime 23 52.8 69.7 Hydrated lime Aug. 11 69.4 Quick lime 14 80.7 Quick lime , 18 64.0 84.5 Hydrated lime As first applied, the lime solution was mixed of the theoretical strength, allowance being made for impurities. As the experiments progressed, it was found, however, that further allowance was nec- essary on account of unavoidable sedimentation in the mixing trough and orifice box, and after the middle of August, 1913, the rate of application was checked by chemical control, analyses of the solu- tion as discharged from the orifice being made three times daily. 97 After April, 1914, samples of the lime solution were collected every 2 hv. into a composite for analysis. The actual weight of lime mixed was varied according to the analyses to give a rate as constant as possible. The copperas was practically a chemically pure product, analyz- ing on July 17, 1913, 99.3 per cent, of crystalline ferrous sulphate. This was applied in a dilute solution at a rate approximating six gal- lons per hour variations being made by changing the strength of the solution. During a portion of the time, the rate of application was- based on the weight of chemical dissolved. Later, chemical control was established, samples being taken as for the lime solution. During the summer of 1914, sulphate of alumina was tried, mixed to give the theoretical dose by weight, no analyses being made. The alum, supplied from the filter plant of the Union Stock- yards and Transit Co. analyed as follows : ANALYSIS OF ALUM. • Constituents Per Gent AljOa+Fe^ds PejOa Sulphates Insoluble Water 17.80 1,36 48.00 0.57 31.44 OPEEATION. Chemical precipitation started on July 15, 1913, with a two-hour period of flow and a theoretical application of 3 gr. of copperas and 5 gr. of lime as CaO pergal., based on actual weight of chemicals mixed. No better results occurring than those from plain sedimentation, the period of flow was increased to 3 hr. on July 28, 1913. As the results continued to be unsatisfactory, the dose of chemicals was increased to 6 gr. of copperas and 10 gr. of lime per gal. on Aug. 4. On Aug. 12, chemical control of the addi- tion of lime was established. The persistance of inferior results, however, was ended on August 23, by the construction of the lime mixing trough previously referred to. Cleaning was made more fre- quently thereafter, as unloading due to septic action had been noticed, from time to time. With the mixing trough and more careful op- eration, a decided improvement in the quality of the effluent soon became apparent. Owing to the poor results obtained during the first 1^ months of operation, these experiments are only briefly sum- marized. RESULTS OF PRELIMINARY OPERATION. Average results 98 for the first IJ months of operation are given in table 53, according to application of chemicals and period of flow. Table 53 indicates that the removal of suspended matter was somewhat erratic, at the start, and but little, better than by plain sedimentation. The removal of organic nitrogen and oxygen con- sumed was appreciably better, however, than by plain settling. During the entire period before the installation of the mixing trough, the effluent from the tank was black in color, containing considerable black scaly material in suspension. The sludge as re- TABLE 53. CHEMICAL PRECIPITATION. REDUCTION OF SUSPENDED MATTER. Day Samples. Grains Per Gallon Period of Flow Hr. Parts Per Million Per Cent Reduction Date 1913 Influent Effluent Cop- peras Lime Org. Nit. Oxy. Con. Org. Nit. Ox. Con. Sus. Mat. Org. Nit. Ox. Con. Sus. Mat. Sua. Mat. July 16 to 25... 3* 5* 2.0 79 232 525 57 128 232 28 45 56 July 25toAug.4 3* 5* 3.0 62 219 538 34 125 390 45 43 28 Aug. 4 to 12... 6* 10* 3.0 78 244 570 44 111 288 44 55 49 Aug. 12 to 23... 6* lot 3.0 67 ,213 528 36 95 238 46 55 55 * By weight. t By chemical control. moved from the tank was likewise very black and sticky. Probably this black scale-like substance was ferrous sulphide, resulting from incomplete precipitation of the copperas by the lime and subsequent reduction of the sulphate under the anaerobic conditions developed in the tank Septic action was frequently noted during this period, with consequent unloading of suspended matter. The odor of hy- drogen sulphide was distinctly perceptible in the effluent. Experiments made in glass jars required considerably more lime to secure adequate coagulation than that called for by the theoretical reaction taking place between the coagulants. Incom- plete mixing and the use of lime for other reactions in the mixture probably accounts for the results noted above, the iron being par- tially or largely wasted. 99 I 2 Ph O IZi O I o Ph i I— I w o 13 O CLi ifi ^ s -aw ^s Ph 8*2 33 c? O a is; H H 1:1 R" ^ o Pi w ^ m s H ■*) 5 o o § << Pi ^ ° a - ■ I w j§ s PS B 00»OOC t^ CO lo i> »> jc^ i> 00 "* • lo -I — I — I— I- U30»OCO»OW3^C<105'^OC3IM inrHcocococoe^'io-^cscoi-Hco T-iO0iC0i0t*O(MiLOC^OO00 CO Cq (N (N -0 OO0S00»O»^U3iC10n'o(NO CO CD t*" •^' CO CO 1-1 ■<4< (M* T-l - i-H Tt< OSCa OOO I> t> CO -CO I>OSCDa>l>Oi-i"^CDOOiOOOOi "^ CO '^f ""sh ^^ ^^ ^^ CO ^^ '^^ ^^ ^^ "^ OIXDOiOOOi-HCO-^t^-OOO rHt^i-Ht-li-lOOS-^OrHOrHC^ COWSCOCOCDCDlOiOCOCOcDcOcD Tt-^00(Nc0C lOCD-^lN (N 1-1 "3 t^ 00 CD CD »0 1— I 1— < OS CO Tji -^ 00 -^ '^ CO COt^CO i-(Ol> >»^2 ) (35 to 00 IM i-H O ,-1 r-1 T-l (N T-1 i-H 3 ^ 0) 9 3 O OJ S 1-5 1-^ ^ ft, g ■«) ^i 1-5 l-J ►-5 <1 i-j<1cc IMi-H _>> >. ti 33^ i-lOjHC^« 13 bO 3 100 RESULTS OP INDIVIDUAL RUNS. OPERATION. The essential data for indiYidual runs after the installation of the lime trough are tabulated in table 54. In general, the chemicals were applied between 8 a. m. and 11 p. m., when the sewage was strong. At night and on Sundays and holidays, no chemicals were used; The average daily number of hours of ap- plication was somewhat less than 15, however, owing to occasional unavoidable shut-downs, so that the percentage of total operating time during which the sewage was being precipitated was corres- pondingly reduced. This was also influenced by the number of Sundays and holidays occurring during a run. The results obtained, therefore, represent a composite of chemical precipitation treatment for a portion of the day, with plain sedimentation for the reminder and on Sundays and holidays. APPLICATION OF CHEMICALS. Some difficulty was experi- enced in controlling the application of chemicals with the compara- tively crude apparatus at hand, in the small amounts required, hence the dosing and mixing were not as uniform as was to be desired. In an actual plant handling large quantities of chemicals with better mechanical appliances, such difficulties could be largely overcome. ANALYSES. Analyses of the day samples of effluent for indi- vidual runs (tables 55 and 56) are corrected for dilution, due to the water used in applying the chemicals, approximately from 1 to 3 per cent. Sunday results have been omitted. REDUCTION IN SUSPENDED MATTER. Table 55 shows the average reduction in suspended matter for individual runs, both for the day samples and for the entire 24 hr. The latter represent a composite of chemical precipitation and plain sedimentation. In general, with copperas and lime, approximately 80 per cent, of the suspended matter was removed from the day sewage, with slightly lower results for the entire 24 hr. The actual efficiency in removiag suspended solids initially pres- ent in the sewage was probably somewhat greater than appears. With plain sedimentation, this reduction was practically the same for both constituents. "With chemical precipitation, the percentage reduction of fixed matter was appreciably less than for volatile mat- ter, probably because of the escape of fine particles of floe. Hence the actual reduction of fixed matter originally present may be the same or perhaps greater than for the volatile constituents. The effluent passing to the outlet nipples frequently showed visually finely divided flocculent matter resembling ferrous hydrate. 101 ■rl iz; ^ o S P a ^ "3 n /t> d K ^ S OJ fL( 1 It fa ^ 1 1 •3 > PS W a CQ 1 2 Pi T) •«! ^ a * +» Pi 1 S d i« o H il-t. .S ■^ir PL, eten- tion eriod tS O f^ <^ P3 n ^ O >3 2^ H O 1 §.o q: ^^ H GOOOOOOOCOOOOOOOCX) IC -^ .CO CQ Tp (M T W O CD T-H O XO T-H ij:5 U^ O lJ lo t-h (m 05 oa 00 CO 05 05 ^ tM 00e0Ir~l^O5(N«3O5CO ■<( -^ -^ CO CO -^ CO CO CO CO o V CDNCOOOT-HlOt^T-H 000500l>^COOCOt^OO»d>00 CO CO CO (N c^ (N cd N .-I oc 05 •iOCO(N p. •Ofl OS lOOO r-1 C> O C O 0> CD 00 Wocnotooow*50 t— * 1-H g H M lOiNCDi-HOOCOCOCD rK TtlOJtOl^OSlfflCOi-l y coiMc00030T-l(NCO II •■a 6 H O t :53 102 REDUCTION OF ORGANIC NITROGEN, FREE AMMONIA, AND OXYGEN CONSUMED. The reduction in organic nitrogen and oxygen consumed for individual runs (table 56) is considerable, though by no means approaching the reduction in suspended matter. A slight increase in. free ammonia was uniformly recorded. REDUCTION IN SOLUBLE CONSTITUENTS. To determine the reduction in soluble matter resulting from chemical precipitation, a few samples of the effluent were analyzed after filtering through absorbent cotton, while the tank was running on a nominal dose of 4i gr. of copperas and 10 gr. of CaO per gal. Analyses of the cor- responding samples of crude sewage were also made after filtration through cotton. The results (table 57) indicate a considerable re- duction of soluble organic nitrogen, averaging 15 per cent., and of oxygen consumed, averaging 42 per cent. Onc^e an apparent in- crease in organic nitrogen was recorded. However, the suspended matter determinations show the removal, on filtering through cotton, in the case of the crude sewage, was not complete, some fine colloidal matter passing through. Undoubtedly the apparent reduction in organic nitrogen and oxygen consumed is affected, as a portion of that recorded as "in solution" may have been in colloidal suspension. The actual reductions, therefore, were probably less than those in table 57. APPEARANCE OP EFFLUENT. On the whole, the appear- ance of the chemical precipitation effluent was noticeably better than the turbid effluent of the other tanks, never being as turbid, and at times was very clear, altho, somewhat colored by the soluble iron compounds formed. SLUDGE ACCUMULATION. The rate of sludge accumulation ' in general exceeded that for plain sedimentation, partly because more suspended matter was removed and partly because the precipi- tated coagulants themselves form considerable sludge. Moreover, all the settled material was retained in the bottom of the tank, in- stead of rising in part to the surface as a comparatively dry scum. Thus the apparent bulk is increased. The rates of accumulation for individual runs (table 58) vary considerably, especially when meas- ured at frequent intervals, due to slight variations in density of the sludge from day to day and the difficulty of accurately measuring small increases in volume The average results over periods between cleanings and for the entire runs are more consistent, however, indi- cating in general a rate of accumulation frequently 2 to 3 times that by plain sedimentation. "With smaller quantities of lime, the sludge accumulation was less voluminous, probably because the iron was not completely precipitated, thus reducing the bulk of floe. 103 o d >, ^ O "A Tl o fJ hH H cS < •fl o Vl ^—1 N CO in' hJ l-H i B rt P m H "=! 1^ f^ S A < o o 1 '^1 Avg. Temp. Deg.Fahr. 11 >■ d Percent Reduc. Volume li Depth on Bed Feet t3 « 1 0| 1 1 2 3 Depth on Bed Feet ■I ■a -a t3 13 io-<* tocq -CM 05 03 IM CO ■* m M OOOtHO (Ni-lrHOOOOOO 3 CO • (N IN 1-1 1> ■* p o ooooooo CO CO . . lO 00 lO ITS U5 iH ■ • CO O CO CO ■* l>^ :§SSS^8SlS ■ oooooooo OMO3 o tf O f3 hn O d g> h^ Pi DQ i 1 p o M O o (^ a CQ CQ 01 >-. >2 >> « « 03 T3T3 •O <1<^3 > o O V m(N'-i 114 W •^ b ■3 ai ^^ R ^ N •1 |fj3 g <6 pq w Q} D9 9>.H « 3?3 ^^ a ° <" 13 C8 P. II -- 03 CD o &«! I oooooo Q B ■-( .Ttl-^OOO OOOOOO t»00CO;D5O'* O • 0%, sg 00 t-t 1-H O CD 1-1 CO eq csi CO CO lo i-H s OS . gggggg d T-i ^ N (N 1-1 d June 24 July 18 Sept. 5 30 Oct. 14 Nov. 6 =1 05 ^1 115 LI CO ^ fl (ji H ^ a ca H d • o ■43 w J H •n, ^ pc] ?1 ^ i t— 1 la ■g r^ ri W O O ft 'A >2 W g- PH •p, g s u b p. OQ I-) f^ no fj g3 O bO tS 3 02 rt o o n Q a. « pq n o a> 0) 03 -HO Ifi ->:> d -, CQ 5^ >^ ■n 03 t^ T3 CM t> u h ^ ^ ^ ^ 9 o d o pq- ^ m ff >> T1 ff O ■O C^) to ■ < 5 CO OSrH OOOCD lCi> lO -sHtOOi CO(N -1 1-4 f— i-H CQt^O5t>-00 lO lO lO C^ i-H O i-H' O 1-1 i-H O COCOO (M ■3 ootw^ioooo o CQ *-t CD »0 Oi O »0 W3 CDI> T o o o o d o d QOOOtH CO d T-l — lO t~ "-I t^ t> 00 T-H wat^^io i-ItH(M ^ooo O O 1— I T-l »-H ^ ft 2 ti 4 116 DEPTH. Sludge was run onto the beds in depths, up to 2 ft., that being the maximum capacity of the bed. The depth of appli- cation of scum was usually less than 1 ft., owing to the small quan- tities ordinarily removed. At the time of removal from the bed, the diminution in volume of the sludges ranged from 28 to 85 per cent. Ordinarily, however, a reduction of between about 60 and 75 per cent, occurred, the va- riations of course depending largely on the original moisture con- tent of the sludge and the content at time of removal. The sludge from the Emscher tank appeared to diminish slightly less in volume than that derived from other sources, possibly on account of the porous character, by which the contained water drained away with less disturbance to structure than was the case in other sludges. The initial depth on the bed did not always control the final volume, for, as the decrease is primarily a function of reduction in moisture, the original depth of application would have little effect in this particular. The scums consistently' showed a considerably smaller decrease in volume because of the lower initial moisture content and smaller total loss of moisture. The reductions ranged from to 61 per cent., being ordinarily from 30 to 40 per cent. TIME OF DRYING. Considerable difference was noted in the time of drying of sludges from the different tanks. The Emscher tank sludge showed a marked superiority, in warm dry weather the surface being usually dry within 24 hours after removal from the tank, with surface cracks beginning to appear and the sludge drawing aw'ay from the sides of the bed. "Within six or seven days, the sludge was consistently spadeable and removable even though applied in depths as great as 2 ft. In case of necessity, this time could probably be reduced somewhat. No water ever appeared on the surface of the sludge, the porous character of the mass appar- ently allowing rapid drainage. Samples placed in k glass graduate showed the characteristic behavior of Emscher sludge, the sludge mass rising to the surface in 5 or 6 hr., leaving a layer of clear liquid underneath. This process was reversed for the Dortmund and chem- ical precipitation, sludges, the liquid rising to the top. "With sludge from plain sedimentation tanks of the Dortmund type, the time required for drying varied from 6 to 22 days, the miaimum time of 6 days occurring but once, few sludges of this sort being removable in less than 12 days. Several factors influence the variations noted, such as the meteorological conditions prevailing during the drying interval, original depth on bed, moisture content and variations in consistency. The sludges from the Dortmund 117 tanks were much more sticky than the Emscher sludge and parted with their moisture much less readily. Surface evaporation un- doubtedly played a more important part in their, drying, as water frequently rose above the surface to a depth of several inches. The scums, in spite of their initially lower moisture content and uniformly thinner depth of application, frequently required a longer interval for drying. The fibrous material, prominent in their com- position, was very retentive of moisture. Even where very thin layers were applied, the scum remained sticky for long intervals. In depths from 0.21 to 1.65 ft., the required drying period ranged from 7 to 29 days, 10 or 11 days being ordinarily a minimum. For chemical precipitation sludge, the. drying period was usually more prolonged than for. the plain Dortmund sludge. The gelatin- ous iron hydrate present in the sludge apparently interfered with the removal of moisture. At certain times the solid matter settled to the bottom of the bed, the water rising to the top. Then surface evaporation was probably primarily responsible for drying, whereas at other times the sludge remained in one sticky mass for days at a time. Septic conditions sometimes developed after application to the beds, large quantities of gas being liberated. The difference in drainability of the various sludges was brought out by the behavior of the underdrains. ^hen Emscher sludge was applied to the beds, the drains begin flowing freely almost immediately, showing the drying to be largely due to the escape of water from below. "With the chemical precipitation sludge on the other hand, the underdrains were frequently very slow to begin discharging and the amount of water removed in this manner was much less. With applicatons from 0.84 to 2.03 ft. deep, the period of drying varied from 6 to 28 days. The sludge requiring 6 days was an exceptionally thin sludge applied to a depth of about 1.0 ft. Ordinarily 18 to 20 days were required during hot summer weather. REDUCTION OP MOISTURE. When removed from the sludge beds, the contained moisture ordinarily averaged from 70 to 77 per cent. In this condition the sludges were somewhat moist, espe- cially in the interor of the mass, but could be readily spaded. After removal from the beds, they were placed in small piles on the ground in the vicinity of the plant. On some occasions, how- ever, the'sludge was not removed immediately on reaching a spade- able condition. Protracted periods of drying, from 67 to 112 days (including time on beds), showed final moisture contents varying between about 35 and 70 per cent. Climatic conditions largely af- fected these results, but during the summer and fall, a reduction to 118 50 or 60 per cent, moisture ordinarily obtained, tlie sludges then appearing comparatively dry and earthy. CLIMATIC CONDITIONS. The sludge beds were constructed in the open, sheltered on the south and west by the tanks, but other- wise exposed freely to the sun, air and weather. The figures for precipitation in the tables are taken from the daily records at the testing station rain gauge, while the air temperatures are taken from the monthly summaries of the U. S. Weather Bureau. Weather conditions undoubtedly affected the drying of sludge to a considerable extent. The sludge from the Emscher tank prob- ably suffered less from low temperatures >and heavy precipitation than did the other sludges, since the withdrawal of water was ap- parently largely from below and the sludge was more porous and easily drained. In the other sludges, surface evaporation appeared of greater importance as the water frequently flushed to the surface, remaining until evaporated. Consequently warm dry weather would aid quicker drying. The non-porous character of the sludge also retained moisture falling on its surface, thus delaying the drying. The effect df covering the beds was studied during the spring of 1914 (table 64), when one sludge was run out to equal depths on two beds, one having an opaque cover. The covered bed required a considerably longer interval for drying, and on removal the residual moisture content was somewhat higher than for the uncovered sludge. During the winter of 1912, the sludge on the beds froze during December, remaining frozen until spring. Further reduction of moisture was largely prevented. With tank treatment requiring the discharge of fresh sludge at frequent intervals, considerable re- serve sludge area would be required, as the freezing of the sludge on the beds interferes with removal as well as drying. The freezing and consequent expansion of the sludge mass may, however, have a helpful effect in rendering it more porous, thus facilitating drying with the return of warm weather. ODOE. The sludge removed from the Emscher tank was in- offensive, although traces of hydrogen sulphide occasionally were found. On the beds and dried, this sludge was entirely inoffensive, having only a slight tarry odor, noticeable only close to. The sludges from other sources were frequently offensive on removal, and, while drying, odors were noticeable in the immediate vicinity of the beds. The scum from the gas vent of the Emscher tank was, however, offensive in odor, though not as markedly as the sludge from other tanks. PILTEEING MATEEIAL. No filtering material was renewed 119 until the fall of 1913, when all of the sludge beds, except No. 2, were resanded to a depth of about two inches. The entire sand layer had then been removed, the sludge being discharged directly upon the underlying gravel. The remaining material was thoroughly washed to remove sludge whith had penetrated into the deeper layers, and was graded in size in replacing. The dates of renewal, the approx- imate amounts of sludge previously treated per square foot of area, and the number of applications of fresh sludge are given in table 65. TABLE 65. HISTORY OF SLUDGE BEDS. Date Eesanded Cu. Yd. Sludge No. Applications Bed No. 1913 Treated per Sq. Ft. of Sludge (Bed cleaned) 1 Sept. 20 0.21 7 2 Not resanded 3 Oct. 4 0.34 7 4E Sept. 20 0.30 9 4W Sept. 20 0.26 8 5E Oct. 14 0.39 7 5W Oct. 3 0.39 6 6 Oct. 14 0.32 7 The original depth of sand on all beds was -one inch. If en- tirely removed when the beds were resanded, an average of one- eighth of an inch might be charged against each cleaning. Cleaning during the winter, when the beds were frozen, probably removed more as frozen sand, adhering .to the overlying sludge, came away in large quantities. Ordinarily the adhesion between the sand and sludge was very slight, only a very thin surface coating appearing on the bottom of the sludge. "When discharged directly on the gravel, the adhesion was greater, the liquid sludge apparently flow- ing into voids of the gravel, keeping the stbnes embedded when dry. With careful operation, it seems as though 12 to 15 cleanings would be the maximum per inch of sand. UNDERDRAINAGE. With the Emscher tank sludge, the un- derdrains began flowing freely almost as soon as the sludge was run on, showing the ready drainability of this sludge. With the other sludges the discharge was less rapid as- a rule and smaller in amount. In the analyses made of the effluent from the underdrains (table 66), occasional high results for organic nitrogen and oxygen consumed occurred, but as a rule the former constituent was low in amount. The free ammonia was universally high, indicating apparently that some oxidization of the organic nitrogenous matter had taken place. There was little nitriflcation, however. The liquid was normally 120 yellowish in color and clear, and being small in amount could prob- ably be discharged with the tank effluent, or passed to sprinkling filters. TABLE 66. SLUDGE DRYING EXPERIMENTS. Analyses of Effluent from Sludge Bed Underdrains. Plain Sedimentation Sludge from Dortmund Tank (Tank D). Parts pbb Million Date 1912 Nitrogen as Oxygen Cons. Reuabkb Organic Nitrogen Free AmrnoTiiil Nitrites Nitrates Oct. 7 '157 53 9 12 15 12 68 33 "i4.4 135 79 88 125 148 110 119 0.064 0.000 0.000 0.002 6! 150 0.000 0.440 0.110 0.004 0.004 0.94 0.23 0.28 0.29 6;66 0.00 1.00 0.31 0.72 0.60 76 67 61 82 107 47 50 63 63 101 80 First flow 8 Second day Third day First flow Composite First flow 9 25...., 26. Nov. 9 9 Composite First finar 22 22 Composite Deo. 4 4 Composite PLIES. During the summer, the surface of slow drying sludge on the beds became baked to a thin hard crust, under which prolific growths of maggots were frequently uncovered, The same phe- nomenon occurred on the surface scum on the tanks. The drying sludge apparently affords a very favorable breeding place for flies. With quick drying sludge this condition does not prevail. MINERALIZATION OF SLUDGE. Typical analyses of the changes in nitrogen, fat and volatile content of air-drying sludges (tables 67 and 68) show that after 2 to 4% months of drying on the sludge beds and on the ground, the sludges and scums from all sources consistently decrease in percentage of volatile constituents. This may be due in part to leeching out of the volatile matter by the rains, but in the main it represents true mineralization or vola- tilization of the organic contents of the sludge. The reduction in percentage of volatile matter varied from 4 to 34 per cent., the well- digested Emscher sludge and the sludge from chemical precipitation showing in general the smallest loss of volatile matter. The latter sludge, containing a large volume of iron hydrate, is initially lower in volatile matter than the other fresh sludges. In some cases a perceptible decrease in volatile content was noted after but a brief period of drying. 121 4- QQ O iS en iij n o d o CO OS T3 03 .a o ffl i OS O •a 1^ IP'S t3 CO >a r^ o fag >°l ^ S3 ■S3 [a o I S "5 CO 00 • «o 05 ^ 05 CO t— I 05 05 CC »0 W3eo rlH (N -^ (N'^tO CO CO US (NTtlOiOO CO CDt^ CO CO o — p .>C 1-1 ■CO 02 ■i — o ■ • in S •CD fi ' -*co H o Q • S : P5 H 00 o odi>.' (N c6co^ (m' (m' (N CO t-4CO COC-^ 02 Iz; o 1— ( ' o ■ S 2,^ ■ a 9<^ 3 2 9 SB 3 « -2 122 ■p. .a tq t4 <^ :S r/j s ^ § ■H 02 •^ -1 00 Q H < H o H > Q ■a P !^ h-i CQ 1 a" « CO to Xi M O "CQ Eg t4 i-H ^1 73 (U CO P4 .ate ^1 ft 113 00 (N N C^ IN N o8 tN' -a S : • -COIN-* • -lOlC CO ORTMUl 2.48 2.52 3.12 2.96 M • ■ (NININ OOININ t~i-l I> t> OS 00 oi ■*t~lN05 t> t> t~.' CO « — Eel UMM5 MOO INIXN CO Ttiuj (N ININ IN(N CDtH OOO V COCDOO lOCDOOTtI i-HlO-^ (N (NININ OINM m-i IN IN-* »H IN IN O "^ fe cj o u COINOOS^-Ht^ eOOOOC^iC cat^cscfl CO t-i00»C 123 In general, the nitrogen content showed a decrease after pro- tracted drying, thongli not universally. The occasional increase found may be due to lack of representative sampling as an actual increase would hardly be expected. A loss in fat was noted con- sistently when this determination was made oh the dried sludge. GRIT CHAMBER SLUDGE. When the grit chamber was cleaned, the sludge was iiushed into the waste drain. No drying experiments were made. However, this sludge was low in moisture and organic matter and being small in amount, should ofEer no diffi- culty in handling. SECONDARY SETTLING BASIN SLUDGE. Very little has been done with this sludge, but the indications are that in thin lay- ers it will dry very readily, largely from below, in this respect re- sembling the Emscher tank sludge. SLUDGE PRESSING. APPARATUS. During the fall of 1913, experiments were made on pressing sludge to reduce the moisture content; with an apparatus consisting of a filter press, a pump for forcing the sludge, into the press under pressure, a storage reservoir for the sludge, with the necessary piping and valves, all located just south of the screen- house. The filter press, of the Kelly type, loaned by Mr. Emil E. Lung- witz of New York City, consisted of a riveted steel cylinder 18 in. long and 9% in. in diameter inside, mounted horizontally. The end opening was surrounded by a steel bearing collar and was closed, when in operation, by a cast steel door sliding on horizontal guides attached to the frame. A tight joint was secured by means of a circular rubber gasket inserted in the bearing collar against which the door was forced tightly by 4 wedges engaging in U bolts and tightened by a hand screw arrangement. The filter leaves, mounted on the door frame, consisted of two parallel flat bags of heavy woven fabric 12 in. long, 6 in. wide and 2 in. apart stretched over rectangu- lar perforated pipe frames forming the outlets for the liquid re- moved in pressing. For further stiffening, pieces of heavy mesh screen were inserted inside each leaf. The total effective filtering area was 2.0 sq. ft. The filtrate passed through i/4 in- pipe^ leading from the filter leaves through the steel door. The material to be filtered entered at the bottom of the press through a one-inch pipe. A pressure gage was, attached. For forciag the sludge into the press, a Kinney Rotating Plun- ger pump, loaned through the courtesy of the local agent, Mr. Carl Heim, was employed, consisting essentially of a cylindrical plunger 124 rotating inside the pump casing on an eccentric shaft. The liquid is drawn in through the pump suction till the capacity for a single stroke is reached, when the supply is automatically cut off by the bearing of the plunger against the pump casing, and at the same time the discharge is opened. All these operations are effected by the eccentricity of the shaft and the design of the suction and dis- charge ports and pump casing. The construction is simple, free from valves, seemingly well adapted for handling sludge. The pump supplied had % in. suction and discharge openings, and, at a speed of 600 r. p. m., was rated at a capacity of 6 gallons a minute. It was driven by a 1 h. p. induction' motor, 1800 r. p. m., belted down to about 500 r. p. m. With this small sized pump some clogging occurred, from the large amount of hair in the sludge. The sludge was, therefore, passed into the sludge reservoir through a screen of 4 meshes to the linear inch. Sludge was supplied to the pump from 50 gal. barrels through a IV2 in- pipe line. In order to maintain a uniform pressure inside the press, a bypass around the pump was provided, in which was set a safety valve of the ball and lever type, and a check valve was inserted in the force main. "When the desired pressure was attained in the press, the safety valve opened, allowing the sludge to cir- culate through the pump. The check valve closed until the pres- sure dropped sufficiently for the safety valve to close. METHOD OF CONDUCTING EXPERIMENTS. Sludge from both plain sedimentation and chemical precipitation was used, being pumped into the press and kept under pressure for 15 to 60 min., or until the filtrate ceased to flow. The pump was then shut down, the liquid sludge inside drained out and the cake removed from the filter leaves. Samples of the original sludge, the wet sludge from the press and the cake formed on the leaves were taken for mois- ture analysis and a sample of the filtrate was collected for the de- termination of organic nitrogen, free ammonia and oxygen con- sumed. The weights of the filtrate and sludge cake were also re- corded. Frequent readings of the pressure gauge were made. In a few experiments the draining of the wet sludge from the press wSs followed by the application of compressed air in the attempt to still further reduce the moisture content in the sludge cake. Owing to the small size of the compressor available (2i^x3 in.), uniform pressure could not be maintained in the air tanks (ca- pacity 10.4 cu. ft.). They were filled to about 22 lb. per sq. in. gage and then discharged till the pressure had dropped to 5 or 6 lb. Part of the runs were made in duplicate and part as individual tests. 125 EBSULTS. In the individual experiments (table 69), the sludge varied considerably in moisture content, running between 90.1 and 98.7 per cent., or somewhat higher than in the tanks. In 2 minutes time the press was filled and put under pressure ordinarily between 70 and 80 lb. per sq. in. At pressures exceeding 90 lb., it was found impossible to make the press watertight around the gasket. In general with most sludges, about 15 min. was required for one cycle after the working pressure had been reached, the amount of water removed thereafter being insignificant in amount on account of the gradual clogging of the sludge cake. Hence most of the tests were made in approximately 15 min. The sludge used in test No. 3 was exceedingly thin, the run extending over one hour before clogging became pronounced. In fact this sludge was sq thin that in attempt- ing to run a second test with it, complete failure resulted, as the pressure apparently distended the filter bags sufficiently to pass the thin sludge through practically unchanged. At the conclusion of the cycle, the liquid sludge was withdrawn, the press opened, and all the sludge adhering to the filter leaves was treated as sludge cake. This cake ordinarily averaged about 1/^ in. thickness, being moist and sticky on the outside with a drier layer adjacent to the filter leaves. When compressed air was ap- plied at the rear of the press after the withdrawal of the liquid sludge, the additional water forced out varied from 2.8 to 12.5 per cent, of the total volume accumulated. The initial air pressure varied from 20 to 23 lb. per sq. in., dropping to a final pressure of 5 or 6 lb. per sq. in. In general the sludge cake treated with air appeared slightly drier than that resulting from pressing alone. Irrespective of the initial moisture content, a reduction to about 75 per cent, moisture, figured on the wet basis, was in general se- cured. Although most air dried sludges may be readily handled at a moisture content no lower than this, the sludge cake removed from the press was uniformly too sticky to be readily handled, even though much firmer than the original wet sludge. The greasy slimy nature of the sludges employed interfered with the efficiency of the process. A subsequent short period of air drying would probably suffice to make the pressed sludge fit for handling, although adding to the expense of treatment. Higher pressures both in pressing and in air treatment, subsequent to pressing, might increase the efficiency of the process. However, continuous rehandling of the liquid sludge remaining in the press at the end of a cycle is trouble- some. Moreover, some of the wet sludge adheres to the filter leaves, thus increasing the moisture content of the cake. A press with chambers in the form of thin flat cells, treating all sludge pumped 126 tf rt 4^ 5 'o § [^ T3 to p^ !^ Li fii ■n -1 s? H (S ►.:; ^ 02 ^- o O Range in Press. Lb. Sq. In. 22 to 5 23 to 6 21 to 8 20 to 7 22 to 2 Vol. Cu. Ft. Free Air 00»-0(N0500000 EQ ■ s » o IS i 1" c IT ■ (M U3 O "^ 1-1 i-H lO -lO ■ - 1> t* t^ t* t- 00 i> -t^ • Wet Press Sludge IT 5 ■t>-00'^ ■i-< -i-f • 1-H ■ 00 i-H i-H (M lO -CO -O - <5^ . ■ t>- O ■ CO 1-H • I— 1 -00 ■ 1 -OiOi -0 05 -OS -OS • 1 1 p 02 o f^ fc H,-((W-^OOCOCQCOi-lO 00 SCCCDCO'^'^CDCDiCiOTh-* 1 £ SS^feSSSSSSsfeg 8 < m r-Hi-ICOCO c CO 3r-IOOrt(M^-*-*00-*C«3(N 1-H 1— t CO 1— 1 Hi .a . 00 i-H s r aaoicQpMpHpHCQCQCQCQpHpH i § P5 i-H(M^i-Hi-HT-(r-l(Ni-HNT-(Cfl 1 (NCSlCC^iOcOt^t^OOOOOSOS 1 go EQPh P4d i§ 127 in during a cycle without rehandling would seem more economical of time and power. Slight differences appear in the moisture content of the original sludge and wet sludge from the press (table 69), which are prob- ably errors in sampling and analysis rather than a real change in the composition of the sludge. Assuming the entire filtrate to come from the sludge cake re- maining on the filter leaves, and adding the weight "of the sludge cake and filtrate, the weight of the original sludge treated is ob- tained. With a total effective area in filter leaves of 2.0 sq. ft., the sludge treated during one cycle varied from 3.61 to 26.92 lb. per sq. ft. of filter area. In general from 4 to 7 lb. was handled, however, the maximum yield being obtained from a sludge exceptionally high in moisture. Assuming that one cubic yard of sludge weighs 1740 lb. (sp. gr. 1.03), this would represent treatment at the rate of from 0.0021 to 0.0155 cu. yd. per sq. ft. per cycle. Under the conditions obtaining, about 15 min. were required for actual pressing. Hence at least 30 min. appear necessary for all operations incidental to a complete cycle, and 16 cycles might -be made in an 8-hr. day with no allowance for repairs, shut-downs, etc. This would produce a rate of from 0.034 to 0.25 cu. yd. per sq. ft. per day of 8 hr. TABLE 70. ANALYSES OF FILTRATE FROM SLUDGE PRESS. ■ • Parts Per Million Test Date Source of Sludge No. 1913 Organio Free Oxygen Oct. Nitrogen Ammonia Consumed 3 14 9 71 Plain Sedimentation. 4 16 103 • 241 i38 Chemical Precipitation. 5 17 62 218 135 Chemical Precipitation. 6 18 18 .278 125 Chemical Precipitation. 7 20 24 81 114 Plain Sedimentation. 8 23 34 96 145 Plain Sedimentation. 9 24 22 128 121 Chemical Precipitation. The filtrate was light yellow in color and somewhat odorous. The analyses (table 70) show a content high in organic nitrogen and oxygen consumed, and exceedingly high in free ammonia. In a system of treatment including sprinkling filters, the sludge press filtrate might be discharged into the tank effluent for treatment on the filters. ' • A few analyses of tlie press cake are as follows : 128 ANALYSES OF SLUDGE CAKE Source of Sludge Specific Gravity Per Cent Moisture Dbt Basis — Percentage Nitrogen Volatile Matter Fixed Matter Ether Soluble Dortmund Dortmund Chem. Precip. 1.03 1.05 1.07 80.0 79.4 75.8 3.00 2.92 2.00 69 73 58 31 27 42 10.7 10.4 5.7 The sludge pressing experiments were somewhat disappointing, as the cake produced could not be readily handled, although the moisture content was materially reduced. However, either higher pressures or a somewhat different type of press, or both might mod- ify these results. SLUDGE VALUES. FEETILIZING VALUE. To learn the probable value of the sludge as a base for fertilizer, four samples were submitted to Mr. W. D. Richardson, the Chief Chemist of Swift & Co., with the re- sults shown in table 71. The grit chamber sludge was fresh, while the other samples had been submitted to protracted periods of air drying on the sludge beds, on the ground and at 4he 39th St. pumping station. Some mineralization of volatile constituents took place during this period of drying, but the loss of nitrogen was slight. The results of these analyses were not very promising. Despite the high content of organic matter in the Stockyards sludge, the nitrogen was not exceptionally high in amount and the other es- sential manurial elements were not present in sufficient quantities to make their recovery very practical from a commercial standpoint. Mr. Richardson stated that the sludges did not appear to have any great commercial value as a base for fertilizer. He did, however, mention the possibility of using a product, dried and ground, as a filler for higher grade fertilizers. Any attempt to use the sludge either as a base or filler would, of necessity, require a greater de- gree of dryness than is attained even after protracted periods of air drying. If a residual moisture content of 15 per cent, is requisite for bagging, mechanical drying would be required. It is question- able whether the increased cost of such drying would be offset by the value of the material as a fertilizer. The high grease content also renders the dried sludge unsuitable for fertilizing purposes, unless extracted. "With artificial drying and extraction of the fat, it is possible that this material can be utilized. 129 TABLE 71. SLUDGE DISPOSAL. Analyses of Sludge for Fertilizing Value Source Percentages Moisture Phosphoric Acid Nitrogen Ammonia Potash Sol. in Water FIGURED TO SLUDGE AS SUBMITTED Grit Chamber 32.8 3.12 0.72 0.88 Dortmund Scum. . 56.6, 0.72 1.00 1.22 Dortmund Sludge . . 26.0 0.76 1.17 1.42 EmscherScum 47.7 0.74 1.32 1.60 FIGURED TO DRY BASIS Grit Chamber Dortmund Scum. . Dortmund Sludge , Emscher Scum . . . 4,64 1.08 1.31 0.03 1.65 2.30 2.80 0.08 1.03 1.57 1.91 0.06 1.42 2.52 3.06 0.09 CALORIFIC YALUE. The possibility of developing the heat values in the volatile constituents of sewage sludge in a practical way has been studied by many. In this case, owing to the exception- ally high content of volatile matter, the determinations of heat values were of unusual interest. Nine samples were submitted to the Gulick-Henderson Co. for B. T. U. analysis, at different times, the source, condition and serial numbers being as follows : SLUDGES FOR B. T. U. ANALYSIS. Number. Source and Condition. 1. Grit chamber; — fresh sludge. 2. Emscher tank ; — fresh sludge. 3. Dortmund tank (C) ; — fresh sludge after filter pressing. 4. Chemical precipitation ; — rfresh sludge after filter pressing. 5. Dortmund tank (D) ;— scum after air drying 90 days. 6. Dortmund tank (D) ; — sludge after air drying 100 days. 7. Emscher tank ; — scum after air drying 80 days. ' 8. Emscher tank; — sludge after air drying 23 days. 9. Rotary screen; — fresh screenings. The chemical analyses of the fresh and air dried sludges (table 72) show that the air dried sludges have all lost a portion of volatile constituents. The moisture content was materially reduced. In table 73 are given the B. T. U. analyses of the samples noted in table 72, with the percentage of volatile constituents and moisture at the time of analysis. On the dry basis, the calorific value of the sludges varies almost directly with the amount of volatile matter, suggest- ing the desirability of drying fresh sludge as rapidly as possible ta obtain the full thermal value, without loss of volatile matter. The 130 TABLE 72. SLUDGE DISPOSAL. Analyses of Sludge for B. T. U. Determinations. Calculated to Dbt Weight Serial Spec. Per Percentage No. Grav. Cent Moist. Remarks Nit. Vol. Fixed Ether Matter Matter Sol. ORIGINAL SLUDGE 1 1.13 55.4 0.88 39.8 60.2 2.8 Grit chamber sludge. 2 1.02 85.3 2.96 72.9 27.1 4.4 Emscher sludge. 3 96.1 3.00 70.6 29.4 10.6 Dortmund sludge. 4 90!l 2.00 66.8 43.3 5.5 Chemical precip. sludge. 5 i;6i 81.3 3.36 74.0 26.0 10.4 Dortmund scum. 6 1.00 95.8 2.32 69.5 30.6 8.6 Dortmund sludge. 7 1.03 79;3 2.56 73.1 26.9 Emscher scum. 8 1.02 91.8 2.73 56.5 43.5 h'.s Emscher sludge. 9 85.5 3.00 93.5 6.6 6.6 Rotary screenings. AT TIME OF B. T. U. ANALYSIS 3 1.03 80.3 3.00 70.6 29.4 10.6 After pressing. 4 1.07 75.6 2.00 56.8 43.2 5.5 After pressing. 5 53.4 2.96* 69.8* 30.2* 8.5* After air drying. 6 24.1 2.56* 41.1* 58.9* After air drying. 7 47.3 2.16* 60.9* 39.1* 'sis* After air di^fing. 8 iioo 76.1 2.92 54.8 45.2' 4.8 After air drying. * About one month before B. T. U. Analyses, fresh Dortmund tank sludges contain more heat units than the well- digested Emscher tank sludge. The difference between Emscher sludges numbers 2 and 8 is interesting. The former represents a sample taken before digestion had become established. The latter was collected, after the tank had become thoroughly ripened, and was air dried for a few days. The reduction in heat value is con- siderable. The chemical precipitation sludge with its high content of inert mineral matter is lower in calorific value than the other fresh sludges. The heat values on the dry^ basis, in general, exceed the figures obtained on the 39th St. sludges from similar tanks, when handled under substantially the same conditions. The higher con- tent of volatile matter at the Stockyards is doubtless responsible for this. Foreign experiments indicate that sludges containing 60 per cent, of moisture can be burned under forced draft without the use of additional fuel. As the fresh sludges from the Stockyards sewage are considerably higher in volatile matter than those de- rived from ordinary sources, incineration should prove correspond- ingly more successful. The high initial moisture content is the chief obstacle to disposal in this manner. As a basis for comparison, a residual moisture content of 50 per cent, may be assumed; then 131 t ^ u oa < 13 « B H cq Q B rt S^U 1^^' ;-3 < XI _2 Tg £ * S .-P T 1 • l§fl 10'^ s-a §i j.ja jd j5 S ^ a o fi fi li; fi p fl [xi H fi OOOSCOOOQOi-tOSOOlO o o ^ ^ a|. i^!^' Theoretiea Available 50 per Ct. Moisture OS 1— 1 CO Tt^ »o . .oo T-H>OC35i-nO . .MO) Theoretical Available Time of Analysis Q0»O00OC0Ot-(U3O 05C0OiCO(Mi-HC0CCCO cot~ioioo>oo SL ^ AU ^ AL OilC^CO-^T-lCOt^T— I ^COCOCO"<*'-HCO^IO i-KNCOTtllOcOt^OOOS f n ■g ^ '. .d T) -e Sa t>i 03 Hi fl O -»A as ^^ 132 taking 1118 B. T. U. as the amount of heat required to raise one pound of water from 60 deg. to 212 deg. Fah. and convert it into steam, the theoretical available heat units were computed, as well as the theoretical available heat units with the actual moisture con- tent at the time of analysis. On the former basis, the fresh, undi- gested Emscher sludge, the fresh Dortmund sludge and the fresh screenings show values approaching 4000 B. T. U. per pound. The air dried Dortmund sludges and scums, the digested Emscher sludge and the fresh chemical precipitation sludge, with the lower content of volatile matter, show considerably smaller values, while the fresh grit chamber sludge with its initially high percentage of inert min- eral matter is even lower still. Figured on the original moisture content, the number of heat units required to evaporate the moisture contained in the frefjh sludges reduces the available calorific value to insignificant proportions. Even though allowance is made for the heat required to vaporize the contained moisture, an additional loss would probably be incurred in volatilizing the fats present, part of which would probably be permanent. ■ Our experience has shown that long continued periods of air drying are required, even under favorable conditions, to reduce the moisture content of the sludges to 50 or even 60 per cent., accom- panied, moreover, by an appreciable loss of heat-producing eonstit- . uents. To dispose of sludge by burning, rapid drying of the fresh product, therefore, appears preferable. The filter press did not re- duce the moisture much below 75 per cent. The calorific value of coal varies per pound from about 7000 B. T. U. for lignites to 12,500 B. T. U. for high grade anthracites. In comparison, therefore, the fresh sludges from plain sedimentation and the fresh screenings, with a moisture content reduced to 50 per cent., are seen to have a substantial thermal value. Artificial drying to attain this moisture content would probably be costly from the mere utilization standpoint, but as a means of sludge disposal it may prove economical some day. Our results . indicate the theoretical heat units available, whereas in actual oper- ation, less would be effective as an efficiency of 100 per cent, would not be obtained under a boiler. Ordinarily, with coal, an effioiency . from 50 to 65 per cent, is secured, and a correction, unknown but considerable, would therefore be necessary in applying these sludge figures. Special grates and furnaces would probably be required. A considerable volume of residue or ash would accumulate, much lesas however, than the original sludge. If the sludge is properly burned, however, this residue should be entirely inoffensive in char- acter, and would be suitable for filling; 133 CHAPTER XI. SCREENING. COARSE SCREEN. RESULTS. The coarse screen protecting the pump was made of % in. round bars set to give a % in. clear opening, and inclined at an angle of 30 deg. with the horizontal in the direction of flow. It was 9% in. wide, with a gross area of 1.43 sq. ft. below the flow line. The screen was'cleaned with a rake, usually two or three times daily. The amount of screenings removed was recorded continuously, the monthly averages being given in table 74 and occasional analyses of composite samples in table 75. TABLE 74. COARSE SCREENING. Amount of Material Removed by Bar Screen in Pump Well. Date 1912 Sept. 17 to 30 October November. . . December. . . 1913 January February. . . . March April May June July August September. . . October November. . . December. . . 1914 January February. . . . March. . April May Average Sewage Screened Mil. Gal. 1.521 3.085 3.464 4.197 4.075 3.211 2.997 3.254 3.494 3.761 4.448 4.409 4.646 5.265 4.406 5.262 3.759 3.232 3.247 3.508 5.218 ■ 3.831 Weight of Moist Screenings — Pounds Total 125 309 333 349 322 260 242 227 248 215 206 304 506 323 400 525 1068 477 154" 313 439 350 Per Day Per Mil. Gal. 10.4 10.3 11.1 11.2 10.4 9.3 8.3 7.6 8.0 7.2 6.7 9.8 16.8 10.4 13.3 17.0 34.4 17.7 15.0 10.4 14.1 12.3 82 IQD 96 83 79 81 81 70 71 57 46 69 109 61 91 100 284 148 47 89 84 91 134 The material removed consisted chiefly of straw, hair, bits of meat, skin and similar material. The weight of the moist screenings varied from 60 to 75 lb. per cu. ft. The odo,r was usually offensive, like decayed meat. Analyses indicated a high content of organic matter and nitrogen, as well as fat. The moisture content seems large, considering the nature of the material which appeared dry and firm. The removal was nominal, as a rule from 70 to 100 lb. per mil. gal., or as the screenings averaged about 82 per cent, moisture, from 12 to 18 lb. of dry material per mil. gal. For a testing station these results are materially different from those obtained on strictly do- mestic sewage, although for working plants- the amounts are within the range of variations reported individually. The pipe supplying the plant leaves the main sewer about one foot above the invert, in a depth of flow around three feet. This may decrease the light floating refuse entering the pump well, and as the plant supply is TABLE 75. COARSE SCREENING. Analyses of Screenings. Date Per Cent Moisture Calculated to Det Weight — Peecbntaqe Nitrogen Volatile Matter Fixed Matter Ether . Soluble 1912 Sept. 17 to 22. . . . Oct. 5 to 11.... 21 to 26.... Nov. 30 to Dec. 6 1913 Feb. 24 to Mar. 2 85.2 79.8 82.0 84.0 78.3 4.24 4.56 4.56 4.96 4.64 83.4 85.7 88.8 86.3 79.3 'l6.6 14.3 11.2 13.7 20.7 12.8 18.0 6.9 13.5 13.6 diverted from the sewer at right angles to the direction of flow, the coarse material sampled thereby may be decreased also. Most of the material actually caught accumulated during the daylight hours, thus increasing the rate of accumulation during certain hours, much above the average for 24 hours. Hence, in an actual plant larger amounts of screenings would doubtless have to be handled, if coarse screening is adopted. FINE SCREENING. GENERAL. The large proportion of coarse fibrous material present in suspension suggested the use of fine screening. The- device tried consisted of a rotary screen (cf. p. 37), covered with brass 135 wire cloth with 30 meshes per lineal inch, cylindrical in shape, 4 ft. 8 in. long, with an effective diameter of 2 ft. 4 in., giving a gross superficial area of 34.2 sq. ft. The area is diminished, however, hy the supporting bands of iron which leave a net effective screen area of 29.3 sq. ft. The screen was revolved seven times per minute. In a screen of this type, to prevent clogging, the material caught must be kept from adhering to the screen, usually by jets of water or air. At first a % in. pipe, set parallel to the axis of the screen and drilled with 1/16 in. holes, spaced 4 in. apart, was placed about 6 in. from the screen, being free to move in its supports, and con- nected by a flekible hose to the water line. The jets of water im- piaged normally on the outer surface of the screen a short distance below the top. The pipe was moved back and forth by a pair of rollers clamped to it which engaged a helical band of galvanized iron encircling the screen, bent to give a backward and forward travel of 4 in. in one revolution. This device proved very unsatis- factory, as the needle-like jets from the sprinkler pipe only covered a very small portion of the screen, and as the cycle of travel was the same as .that of the screen, the jets continuously followed the same path. A stationary pipe was substituted, into which were tapped at 4-in. intervals %-in. nipples, 2 in. long, flattened at the outlet end to give a fan shaped spray. To further increase the effi- ciency of distribution, these jets were directed against a sheet of galvanized iron bent to proper shape to deflect the spray against the screen in a continuous film. Water for cleaning was -taken through a meter directly from the line supplying the testing station. An attempt was also made to investigate the efficiency of com- pressed air as a cleaning agent, but the small compressor (2% in. x 3 in.) available was totally inadequate for furnishing the necessary volume of air at the required pressure. OPERATION. Three separate runs were made with the screen; one during the fall of 1913, when it was in operation 'daily from 8 A. M. to 4 P. M., one run in May, 1914, from 7 :30 A. M. to 10 :30 P. M., and one in July, 1914, when it was in operation between 8 A. M. and 11 P. M. For a few days on the second run, the operation was continued throughout the night. EATE. The screen was operated at rates varying from 117,000 to 235,000 gal. per 24 hr. With a net effective area of 29.3 sq. ft., this corresponds to a rate of from 4,000 to 8,000 gal. per sq. ft. per 24 hr., or with a rotative speed of approximately 7 r. p. m. to a treat- ment of from approximately 0.4 to 0.8 gal. per sq. ft. of clean screen exposed. However, as the sewage did not actually reach the outlet end of the screen, the actual rate of application was somewhat higher 136 aa ad, aa oi d. ?ij^i ill 1— l.-H{N.-lr-:li-(rHT-lT-li-(i— I all 13" •OOiOi-lOCCOOcOCQCDt^O(00 T3 E3 E ^CDTHOCOCOCCOOOiO'-iiOiOGs-^^0500-^03'*CSt^l>-eOt> i-H t^ CO CM -^ -^ CO C5C0COlOOi00l>OTl»0-^OQTHT-(»000-^i- OOOOOOOOOOOOOOCO'>*r(<0000000000 i-HCQt^.-HCOasOOCOlOOOCO^H,-IOOOCOOSOO^-^^"3COt^lO (NCO'*t~COTitO'>*'*-<*t»tOU5t-10(NtOt~000 OOOOOOOOOOOOOOINOOOOOOOOOOOOO C00000TjH000SC0C0i-lt^00i-H00Ot*-*O»O00C^r*C00St*C0»H»0 co-^uDoo-^wscooiooocoi-tciOioiocooooot^ast^cowooot^ 3'^l>OQOSOi-HCOt*^(MCO-<*H g « QQ ^ rl H o ^ Pi (^ I ^ ^ a 3J '^ ^ o ! «ja 3 i « 3 S m !.• H PQ ^ « 3 .3 8 3 ^§,g Ph w ^=i&w tf o (M t--t-.THg;t~0'*;*T)o-*co>OTti'*u5-*-^ CO (W^-^-^eo^TttmcoiN «'*<■* • i-H • 1-1 O cc CO O 05 Oa 05 03 05 t* OS 03 03 • ei • CO th CO CO ■^" CO CO CO CO CO CO CO CO cq • CD ' CD CD CD CD CD CD CO CD CD CD CD CD CO CD ioino«iiomw>>nmo>o>o>ooooooo>no>omoo i-ICOOOCOO'*COOOO:CD-*OCOQOCOCONOi-I'*tHOO'*0100 lOt-OOa"500COC»t~050t-INC»OOOT))l>asCO>-lCOCOOOCO Soooooooooooooooooooooo o.o l>.100(MlOt^r^Ol000050-^COCOOOCO»000»OCOOO c^T'^cDio'co'ic'-^io'cDi^'orcd'^oocD'ooi-ro'oooorT-rtCcDO COCOCOCOCOOOUS030cD»-(eOt>-lOCOCDC50t*CD0500>U3t~ i-HjcocOT-Jco^tiioc-ilvco'oioJM'ooi^t^t-t^oor-rOOcoo^co OOOOOOC»OOOOOOOOOOOOOOQOOOQOOOCX)QOOOCOOOOOtlOroOOOO 500000000000 5000000000S0 gOOOOOOOO' ooooooooi W 03 CO iC OS •<:t^ 00 O CO I ori>r CO cT i>rtC i>r lo* i> t>r of cxf 00 00 cT 00 ^00 00 00 00 00 CO C3" 00 C^"^»OCDCDt^»OCDt^CDt*l>t^t^t^lO»-lCOt*t^l>t>t*COt^ oooc oooc oooocoe li3C0'O»0OOU3OOOOOOOCb^i>odcDcDo6t~^o6o6odododi>corHi>odo6o6oooocooo soooooooooooge ■ soooooc ooooooQOOOooooooooogoogoo c3oOO>000(MOOOOlOOOOCDOOOOOOOOO o_o_ ^ocD"•*"co"cooo>o>-ieot-(Nco'*r-ooosT-i(McO'^>oosOT-; (M(M(MlSl(Mc5C^ coco r-l.-lrt>-li-(i-l i-l"-! 140 § ^ I S ° 3 ^ rrs 'S So @p^ o I— 1 Per Cent Wash Water • CO (>i CO « CO • ■ • '• i i ! 1 ; Moist Screen. Lb. per Cu. Ft. 1 — — • lO ira IM lO IN Screenings Lb. per Mil. Gal. >> •i-tcD-^oo-^ .-*(MCO(NCO -1^ 1 :J:;2!SE?oo :::::;:;: • C<1 »— I 1— 1 1— t »— 1 Screen- ings Per Ct. Moist. •(NOOCOOiCD i^ ■ i-H t^ (N (N r-l §1 o s :§g§gS ;:::::::: :S^^g^ ::::::::! Hours Oper- ated oo -oooooo -oooooo .oooooo -ooooo • ■ 03 O 03 C^ O ' . i PU m o Per Cent Wash Water l>-^ • O CO iO CC CO 00 • -sP CC CO co-io c<» • 00 00 (M 00 CO t- -oot^ot^o ■ .^ ■ t-( CO 1-i cq t> T-l ■ 1-H •<# 00 CO t* ■ . l>X> • to (O Th lO Th lO ■C0CO-*-*^'O •CO(MCOCO(NCO -COCO-^CiKN ■ ■; Moist Screen. Lb. per Cu. Ft. ■ ■ - (NtN Tt* CO O 00 . CO -^ I> Cq 00 .-^ • CO CO 00 CO t- no •CO'JttOO • • • ■ • I— t CO »o C^ O O ■ t>. tH o ir* -^ »— < . ■ . »0 lO iO »0 tH CD ■ Tt< -^ lO -^ -^ -^ •i-lCD(Mi-H00O5 -t^lOO-* . . •. ■ lO tH >0 lO ■* CO .-^TtlW* . . j Screenings Lb. per Mil. Gal. (M lO -CDCOOlJOt^O ■ Til ^ CO O 00 lO 00 o • ^ c*a CO t^ CO CO ■ T-l O CO CO lO 00 TjllO • 00 T* ■* ■* CO CO • ■* CO Ttl Tjl Tj( CO 1 ■ iO CD Tjl lO CO CO -lOiOtXDiO ■ ■ .1 o oo .oooooo .oooooo T-f T}< .005T*0(MO . 05 lO 1-1 CO O CO Oira . UO CO 1* I> Ol CO . 00 I> 00 «5 I> t^ ;8§SgS8 ;S2gSS : :• ■ co'c^Tcifcfi-rT-r ■ c^csTcoco'n ■' • Screen- ings Per Ct. Moist. OW • OJ (N ■* tH 0> in • 1-1 1> ■* O 00 l> - (N lO »0 CD CO lO -OSi-lOliOCO • • •^a ■ r-i c^ CQ (N O 0000 -00 00 00 00 00 00 ■ t^ 00 00 00 00 t^ ■ i-H no C^ O OS t^ -OOOi-HGOO • • ■ 00 t^ 00 00 t> t^ -oot^oot^oo ■ ■ §1 Is go ;oogooo ;oooooo Ot-H •TT'-HUSOOCOO ■ i— J^i— t 1-H i-H rH .— ( oTco ! cd"co '^o'cD q" ! co"co co'co'co'cd' coi>i .co«>i>-*co^ . 1> t-~ t- t> t^ lO :gooooo :ogooo :• "coi— ii— ii— ii— 100 "i— it-Ht-H i-f^T-j^ ; . '.cccoeococfs-^ : CO CO eo^co-co *. ■. Hours Oper- ated oo Scooocoiocq Soooooira Eooooon"5"5'0"5'-i i-H g 1-H .-* i-H »-t ^ ^ r-( ,-H i-H T-t rH ■STtHioicuoioos"o»oiouDio»n"o"o w 1— I 1— ( 1— 1 1— 1 1— 1 1^ 1— ' 1— 1 »-H 1-HH j2 g 1 p: Gallons per 24 Hours oo -oooooo ^-oooooo o o >>o o o o o o >>o Q o o o o oo osooi-toioo ^oooooo 1-HrH 2t— (.-Ht-Hi— (i-Ht-H Si— (t-Hi-Hi— (r-tr-l --lT-Hj^--lr-l,-H,-lr-(rtjjj,-HT-l,-Hrtrt,-H ^gogoog^goooo^ aoSooOo^SS q,o_q_.g » ; Date May, 1914 ^(MCO^U5COt-OOC»0;-;2CO^«5cgt^0030jHC3CO;g;^CDgjOOgOH 141 weather conditions, if spread in tliin layers and turned at intervals to expose the under layers to the action of the sun and air, .rapid drying should ensue, and the remaining residue could be disposed of by burning. Some odor might occur, as putrefactive conditions tend to develop rapidly in the moist mass . The volatile constitu- ents were reduced during the drying period, the original .sample containing 97 per cent, of volatile matter and the dried sample 87 per cent. AMOUNT OF MATEEIAL REMOVED. Tables 78, 79 and 80 show the amount of material removed both as pounds of moist screenings per million gallons and as pounds of dry material for the same unit for the three runs. The screenings were shoveled from the discharge trough into the weighing can during the first run and were slightly drier than as actually discharged. On the second and third runs they fell into a perforated can, the surplus moisture draining away. Nevertheless, they were readily handled, consider- ing the high moisture content, ranging between 85 and 89 per cent. On the wet basis, from 3,000 to 12,000 lb. of moist screenings per mil. gal. of sewage may be expected during the hours of heavy flow. Jlxtending the run into the evening hours reduced the amount to from 1000 to 4500 lb. per mil. gal. Seasonal variations in strength of sewage and fluctuations in moisture content of the screenings may account for some of the difference observed. Reduced to the dry basis, these figures range from about 500 to 1400 lb. per mil. gal. for the first run, and from about 194 to 815 lb. for the second and third. The unit weight of material varied somewhat (tables 78, 79 and 80) according to the degree of draining and compacting, but in general the specific gravity of the material as discharged slightly exceeded unity, showing that a portion at least will settle under nearly quiescent conditions. On the second and third runs the material was more thoroughly drained and consequently more po- rous than on the first, and the unit weights were correspondingly lower. From 85 to 184 cu. ft. of moist screenings were removed per mil. gal. during the first run. As a remedy for excessive scum formation on settling tanks, the use of fine screens was suggested herein (ef. p. 66). It also seems desirable to reduce the amount of sludge to be handled, as the moist screenings are more easily cared for than the liquid sludge. Dry screenings at the rate of 500 lb. per mil. gal. represent a reten- tion of about 3 cu. yd. of 90 per cent, sludge or 2 cu. yd. of 85 per <;ent. scum. CLEANING. Water from the city main was used, at a very 142 H 9 30m rt rt 1^ S § 9 «g .s .a ss <0 t-i S Or 3 S w p. o •4J o o S3| >n 00 "o 00 00 lo ■ .-1 10 1^ (M m s~ ••^t -cocoo ■mooNrt t^OC^COOi-( •i-ttOOCDi-tO '(NO -OSt^OQ • (M t^ i-^ O O i-IOOCD-^WeO ■ IM (N CO 1-1 CO IN ■ IN t- ■ CO tO CO • CO >0 CO Tf ■* i-l "H t~ t~ (N 03 ■ IN ■* i-l 00 O r- -t^i-l -OOOlO -usooooo i-H,T-t(NOr-t03 ■CD^OpOOOS -i-HrH .MMCg '^QrHlO 00O5'*t~00-* op CD »0 »0 CO 1-1 ?fi CO ■* (N IN CO ■ C<1 (N IN CO CO Cooio>no .010 .wow .00000 ■rticoeot^a^cD .cococoosi-io .-^lo .t^coc^ .c^rH^coo 00 03 T-l -* 1-1 CO . T-l T-IIO CO t* O .OCO .CDCOW .OOOCOOOI> lOOst^WOOi 'COiOWWON •■^W 'OOOON 'OOOSCONCO ■ c^iooco -oacDooosi-i •00t~t- • t» t- t». t~ CX) 000000 000000 CO IN 1— I rH F-l r-l •000 -ooooo •000 -ooooo ; 1-4 1—1 O • 1-H 1— ( 1— I j-( iH '. coco~co '. mmcocom ^~co CDi* oooe lA LO W L 000000 00 -oow 000 U3WW310WU5 lOlO .1— ti— li— ti— li-Hi— I ^i-li— I 00 W 10 1-1 lOlOWlOlO 00 00 00 000 000 000 o 12; o li 00 ss o 0000 00 Q 00 O 00 0_0 kTOO T-l 1— I ^H 1-1 liS '-I i-< 1-1 T-1 1-1 1-1 glH 1-1 SQ CDt*00 05 0i-1NCO'^lOCOt*00 03 0i-lCHCO'^U5COt*OOOSOiH i-li-li-li-li-l.Hi-li-li-li-iiNINC1(NIN-] P OS H O lie) CO g 111 :3 _i ^ < g o p5 o CO CQ O t— I 12; iz; •-» ^; o CQ H ai rn ^^ O ^1 (2^ =2^ 0813 1w °3 ^ ^5 SCO q2 CDCOlOO>t> t^ ^1 -^ -^ -^ -^ ■* §1111 o lO rH T-l tHtH i-i OT)(tDO>0 05 MO eD(N (M (N 00 00 00 00 00 00 ooooo S' t^ 50-*l>l>l> CO O-^Oi-fT-t 00 l^rHCOrHtO 1 tH r-l 1-H (M i-H w Ph 'm r/i § ixmiM^mi (N(N lNCO(M s »-(Tt< lOt-i t^ to .-(.-I-*I>«1 CO o iz; O g° :gt2Sg o o o o o o (b (M(M tO5OO0C CO 00 03 »-( (M~i>.~co~.-rTtrc.~i>.~cm"-*' ^ CO »0 ^O T-H lO CO >-( rHCtllNCM OI>-*(M^O-* Ir^ to t^ to CO t>- 1* ddddcidd d ||sg||| 1 11:00 a.m. to 3:00 p.m. . 1:15 p.m. to 2:15 p.m. 2:06 p.m. to 3:36 p.m. 10:30 a.m. to 3:30 p.m. 8:30 a.m. to 3:30 p.m. 8:45 a.m. to 3:45 p.m. 8:30 a.m. to 3;30p.m. ^S5?5?§g^S 1 147 actual analyses of the influent and effluent. This is due largely to the difficulties of representative sampling, the short duration of the tests, and the fact that the coarse suspended matter removed by the screen is not adequately represented in the small portions taken for analysis. The per cent, removals based on computed analyses are much more consistent and probably represent more fairly the actual performance of the screens. On this basis the Jennings screen showed an average removal of about 33 per cent, or 127 p. p. m. while the Sulzberger screen apparently retained about one-fourth of the suspended matter, representing an average removal of 202 p. p. m. The Jennings screen receives a deal of coarse suspended matter such as pieces of corn, straw, etc. Table 82 shows the removal of suspended solids both as moist and dry screenings in lb. per mil. gal. On this basis, the Jennings screen removed about 6740 lb. of material with 83 per cent, mois- ture, equivalent to 1150 lb. of dry matter per mil. gal. The Sulz- berger screen results fluctuated more widely, varying from 2320 to 17,400 lb. of material, with an average moisture content of 84 per cent., or from 320 to 2820 lb. of dry material per mil. gal. The average, weighted according to the volume treated, was aboul; 10,- 790 lb. of moist screenings or 1690 lb. of dry screenings per mil. gal. SCREENINGS. The material retained by the Jennings screen had a dirty greenish brown color and contained a very high per- centage of volatile matter. The material removed at the Sulz- berger plant was similar to that at the testing station. The high moisture content found at the testing station was noted in these tests as well. ANALYSES OF SCREENINGS. Sewage from Stockyards and from Sulzberger Sons Co. Per Cent Moisture Det Basis — ^Percentage Screen Nitrogen Volatile Matter Fixed Matter Ether Soluble Jennings Sulzberger 84.3 85.1 1.71 1.31 91 93 9 7 2.6 5.8 CLEANING. The compressed air used to clean the Jennings screen was very effective, blowing the screenings completely away. The blast, however, gradually destroyed the screen cloth. The high pressures should be reduced, to avoid costly replacement of screen fabric as well as expense for power. Experiments along this line are under way. 148 Air was supplied for the Sulzberger screen in so small a main that the pressure available proved too low to produce any marked cleaning effect. However, the screen was thoroughly cleaned with a fire hose after each run. One point brought out in the operation of this screen was a clogging effect due to the congelation of grease in the meshes of the screen, stopping one test after a run of one hour. Careful attention to this detail is evidently required in handling straight packing-house wastes. LOSS OF HEAD EXPERIMENTS ON MESH SCREENS. OBJECT. These experiments were conducted to determine the amount of sewage of the character received at the Stock Yards testing station which can be handled by screens of different mesh, the rate of clogging, and the relation, if any, between the amount of material retained on the screen, the rate of clogging, and the quantity of sewage treated. APPARATUS. The apparatus (fig. 14) consisted of a square box of galvanized iron with pyramidal top and watertight joints. The screen to be tested w;as placed over the open bottom, being held in place between two wooden frames, one of which surrounded the outside of the box being attached thereto. The outer or lower frame was detachable, with a rubber gasket inserted between, the frames being held together by carriage makers' clamps. From the main orifice box, a two-inch pipe supplied sewage through the top, a flange union facilitating quick breaking of connections, being inserted. An air vent was also provided. The screen box was set in a larger -v^rooden box of tank con- struction with an overflow weir sufficiently high to keep the screen constantly submerged. The effluent discharged into the waste drain. The head on the screen was measured by an adjustable glass piezometer tube, with rubber tube connection to the side of the. box, a constant level being maintained outside the screen by the over- flow weir. As originally designed, the screen box was exactly two feet square inside, but this was cut down to accommodate the screens already on hand, by inserting a wooden frame. The effective screen area was 3.5 sq. ft. The apparatus was designed for a maximum loss of head of 5 ft. but in actual tests 4.5 ft. was not exceeded. METHOD OF CONDUCTING EXPERIMENTS. Screens of eight different sizes were employed, of 4, 6, 10, 16, 20, 24, 30 and 40 meshes to the linear inch, with mechanical properties indicated in table 83. Duplicate runs were made on each screen, except the No. 149 \J^/>-/7e//ef Croc/e 3 ey\/cfgfe ■Oyerf/oi/\/ y\/efr -J"P/peHi7s/e SECTIONAL ELEVATION ' — 7^ /Vasre Dra/r7 PLAN 1 iiiiiii uL Scale -Feet Fig. 14. Apparatus for Screening Experiments. 150 4, on two and in some cases on three separate days. Piezometer readings were made every 15 sec. as soon as the screen began to clog. TIME OF CLOGGING. The average results for screens of dif- ferent mesh (fig. 15) show curves similar in form, indicating in general that when once the screen begins to clog, the loss of head increases with great rapidity, despite iadividual variations. Some difference is noted between the fine and coarse screens, after ap- preciable clogging appeared, the No. 6 screen requiring 7 min. to rise from practically zero to the final loss of 4.5 ft., whereas for the No. 40 screen the time in no case exceeded two minutes. The time required to produce clogging varied for difCerent runs on the same mesh. With this sewage, however, constantly changing in strength, the wide variations in suspended matter content would produce con- siderable fluctuations in the time of clogging. With the finer screens, the total time to reach the final loss of head was very short, not exceeding 6 min. for the No. 40 screen. With larger meshes, the average length of run increased but indi- vidual cases of very short runs occurred with screens as coarse as the No. 16, suggesting that *he details of cleaning must be carefully TABLE 83. LOSS OF HEAD EXPERIMENTS. Properties of Fine Screens. Meshes Diameter Net Opening Open Space per Lineal of Wire Length of Side Per Cent Inch Inch of Nominal Inch Millimeters Gross Area 4 0.048 0.198 5.04 65 6 0.034 0.137 3.48 64 10 0.026 0.072 1.83 54 16 0.019 0.042 1.07 42 20 0.016 0.034 0.86 46 24 0.0133 0.029 0.74 42 30 0.012 0.022 0.56 41 40 0.010 0.015 0.38 28 considered where fine screening is used, if undue clogging is to be prevented. Clogging with the No. 4 screen proceeded very slowly. Of the three runs, one reached the 4.5 ft. loss of head after 5 hrs. 30 min., the remaining runs, after intervals of 7 hrs. 30 min. and 6 hrs. respectively, having a loss not exceeding 0.01 or 0.02 ft. In all these tests the sewage passed a % in. bar screen before reaching the loss of head apparatus. A few runs were made on the No. 30 and No. 40 screens at a 151 ^ ■ ■rv -fe 1 •6 t^COiOiOCO(Mt*COlO-<*»(NCOc^T*^lOlC^*cqrHl-^(^^co1-^oscd^^^050i p 153 lower rate, approximating 6840 gal. per sq. ft. daily. The duration of the runs increased somewhat, averaging 9 min. 27 sec. for 4 runs on the No. 40 screen, against 5 min. 16 sec. for 7 runs at the higher rate, and 46 min. 7 see. for 3 runs on the No. 30 screen, against 8 min. 36 sec. for 6 runs at 14,800 gal. per sq. ft. daily. The average time for the No. 30 screen at the low rate was high, principally owing to an unusually long run on Sept. 22, extending over 76 min. 22 sec. With a low rate, the loss of head increased more gradually than at the high rate, extending over 4 or 5 min. at the low rate compared with 2 min. for the high. EEDUCTION IN SUSPENDED MATTER. The analyses of in- fluent and effluent samples, with the percentage reduction of sus- pended matter (table 84), show considerable variations in the strength of the crude sewage, as well as in the per cent, reductions. As all the experiments were made between 9 A. M. and 4 P. M., when the sewage was strongest, the results are typical of the worst conditions. The percentage reduction in suspended matter was very erratic, varying between wide limits for screens of the same size and fol- lowing no clearly defined rate of increase for decreasing size of mesh. In fact a considerable decrease is noted ia the average results in some cases. This apparent fluctuation in efficiency was probably due to the'difficulty of collecting representative samples, and to the short duration of runs, as well as to actual variations in efficiency and sewage applied. Since the larger particles of suspended matter are retained on the screen, thus removing one source of sampling errors, the effluent samples are presumably more typfcal of the actual composition of the liquid than are the influent. In table 85 are indicated the actual analyses of the effluent and computed analyses of the influent based on the weight of dry materiS,l retained by the screen and the quan- tity of sewage passed through. The percentage reductions are figured also on this basis. For comparison, the actual analyses of the influent and percentage "reductions based thereon are shown. The calculated figures in general indicate a progressive increase in efficiency with decreasing size of mesh, the fluctuations in individual cases being much smaller. This probably represents more closely actual conditions, as the .finer screens are undoubtedly more effi- cient in removing suspended matter. Owing to the difficulties of sampling, however, the relative amounts of material actually re- moved by the various screens are a better index of efficiency than are the percentage reductions of suspended matter. These latter figures indicate an average percentage removal of from about 13 154 TABLE 85. LOSS OF HEAD EXPERIMENTS. Reduction in Suspended Matter from, Computed Analyses of Influent. Date Size of Screen No. of Runs Avgd. Rate,Gal. per sq. ft. per 24 hr. Suspended Mattee Pabts per Million Influent Actual Com- puted Effluent Per Cent Reduction Actual Infl. Com- puted Infl. 1913 Aug. 6 6 2 14 6 3 Average 5 Sept. 2 10 1 2..... 10 1 3 10 2 5 10 2 Average 6 July 18 16 2 Aug. 15 16 1 15 16 1 Average 4 Aug. 8 20 2 12 !20 2 Average 4 July 24 24 3 Aug. 15 24 1 15 24 1 Average 5 Aug. 7 30 2 12 30 3 21 30 1 21 30 1 Sept. 2 30 1 3 30 2 Average 7 Average 3 July 17 40 2 29 40 3 Aug. 8 40 2 22 40 1 29 40 1 29 40 1 Average 7 Average 3 14,800 620 14,800 ,420 14,800 500 14,800 14,800 14,800 14,800 14,800 14,800 14,800 14,800 14,800 6,840 6,840 14,800 6,840 14,680 14,720 14,800 6,840 6,840 6,840 14,730 6,840 660 460 660 420 547 14,670 560 14,800 750 14,800 750 14,740 655 14,750 770 14,800 680 14,780 725 14,700 500 14,800 570 14,800 640 14,740 542 1200 700 390. 540' 470 520 776 497 720 510 730 490 920 840 633 750 680 452 543 492 368 713 418 520 644 740 807 709 785 605 695 594 621 765' 634 1018 689 514 611 404 679 747 587 836 605 914 521 968 864 759 784 610 380 472 450 330 640 380 470 510 620 720 590 670 500 585 460 520 620 504 890 520 390 440 300 590 596 493 600 450 680. 390 710 640 659 580 2 10 6 32 28 3 10 14 9 17 4 10 13 26 19 8 9 3 7 26 26 18 36 13* 23 1 17 12 7 20 23 24 12 24 10 16 13 10 10 9 10 21 16 11 17 15 17 16 23 16 19 21 13 24 24 28 26 13 20 16 28 26 26 25 27 26 26 27 *Denotes increase. Note. Final loss of head equals 4.5 ft. 155 o n ^ ^, ^ id g i Ph h CO g a ^ "^ >H S 1;^ -i °9 < 1- s f^ d o q CO OS O fi^ <1 I I S3 § Ph ftft COCC o rH ^i-ii-t OOOOOOOOOO §!? < o M »o o (M lo o in la OlOlNCDOOU^OOlO Tt<000000«i!OT-ii-irfi 1-1 00 to CO rH m_oo Oi^,"-! 00 12; o o O • -S Ah 02 o !z; p O .o .OC0(M>0O .00>Ol>CO(N .ooco , T-ICDCD , O5_(M_00 w 02 o Ph o Ph o HT*(00rtO-*O«SIN^ O M I> O lO 00 lOO IC IOr-lTirT-r OOOOOOOOOO oooooo-*oo-* 0000000000000000 00_00 1^ ■^" -Ttn" Tt^" -^ TjT CO" tH' TjT ccT ■t^COOcpcOt-OOCD^ ■1— 1»— (T-tOOOOOO ■OOOOOOOCJO •0000»OCOCDr*i-H-^O5 •(NCOC. SOScreen A/oAOScreer: AOO 800 leOO J600 IMO SMO Dry Screenlngs-fhuncb Per M////on Ga//ons zaoo Fig. 16. Removal by Screens of Various Mesli. Note. Dots represent Individual Runs. All data secured with apparatus In Fig. 14. 158 mulation (table 86). The reasons for this are uncertain, although changes in character of the sewage may be largely responsible. The amount of material removed per mil. gal. is much greater than- for similar tests at the 39th Street testing station, even making allowance for the fact that most of the latter were made to a final loss of head of 0.4 ft. (table 87). Table 87 shows that, except for the No. 4 screen, four to six times more suspended matter was screened from the Stockyards sewage than from the 39th Street. TABLE 87. SCREENING EXPERIMENTS. Comparative Results Obtained with Mesh Screens on Crude Sewage at Stockyards and 39th Street. Size of Screen Nom. Mesh Stocktabds Sewage No. of Tests Gal. Per Sq. Ft. Daily . Dry Screen'gs Lb. Per Mil. Gal. 39th St. Sewage No. of Tests Gals. Per Sq. Ft. Daily Dry Screen'gs Lb. per Mil. Gal. 4 6 10 16* 20 24* 30 30 40 40 3 14,800 134 4 14,800 654 6 14,800 421 4 14,800 992 4 14,800 919 4 14,800 1113 6 14,800 1259 3 6,840 776 7 14,800 1674 4 6,840 1290 12,000 12,000 12,000 6,150 12,600 6,150 6,150 87 121 117 2i6 igo 206 295 * Not used in 39th St. tests. \ Note. StockyaHs tests carried to final loss of head of 4.5 ft., 39th St. experiments to 0.4 ft. TABLE 88. ANALYSES OF SCREENINGS. Date Size of Specific Calculated to Dry Weight Per Cent Screen Gravity Nitrogen Volatile Fixed Ether Soluble 1913 July 10 24 2.72 ' 6.62 18 16 2.96 6.56 29 40 0.99 3.28 90 10 7.42 Aug. 7 20 1.02 3.36 90 10 8.44 12 30 1.03 3.68 87 13 6.66 21 30 1.03 2.88 88 12 5.30 159 ANALYSES OF SCREENINGS. The material retained by the screens resembled that caught by the rotary screen. With the coarser screens the screenings formed a mat-like layer, which could , be stripped with' little difficulty, leaving the meshes comparatively clean. "With the fine screens, on the other hand, some of the mate- rial was forced into the meshes, adhering so firmly that scrubbing and washing was necessary to clean the screen thoroughly. Typical analyses are given in table 88. LOSS OP HEAD EXPERIMENTS WITH SLOTTED PLATES. GENERAL. Beside the experiments on mesh screens, tests were made on slotted iron plates. These slots were cut square and were riot bevelled on one edge as is done in the Riensch-Wurl screen. Three widths of slot were provided, the mechanical properties of TABLE 89. MECHANICAL PROPERTIES OF SLOTTED PLATES. Designation Dimensions of Slots , Inches Area of One Slot Sq. In. Gross Area Plate Sq.Ft. Per Cent Net Open- ing to Gross Area Length Width Distance C. to C. . Coarse Medium Pine._ 1.00 0.0625 0.50 0.032 0.50 0.025 0.198 0.125 0.083 0.0625 0.0160 0.0125 3.5 3.5 3.5 28.4 17.6 17.2 these plates being indicated in table 89. On the coarse plate the slots were staggered, in the others the slots were arranged diagonally in 42 rows, 1/6 in. apart. The tests were run to a uniform loss of head of 1.5 ft., at a rate of approximately 11,100 gal. per sq. ft. per 24 hrs. TABLE 90. INTERVAL REQUIRED TO REACH LOSS OF HEAD OF 1.5 FEET At Rate of 11,100 Gallons Per Sq. Ft. Daily. Size of Slot No. of Runs Time foe Final Loss of Head in Min. and Sec. Average 1 Minimum 1 Maximum Coarse Medium Pine 7 8 8 28-45 9-08 7-14 12-32 5-00 ^05 43-18 12-04 13-19 160 TIME OF CLOGGING. The average, maximum, and minimum intervals required to reach the final loss of head (table 90) indicate that the loss of head proceeded somewhat more slowly, if more irregularly, than with the mesh screens after clogging. Runs of short duration on all three widths of slot indicate that the details of cleaning would require careful design to prevent undue loss of head with rates approaching those used with plates having substan- tially the same percentage of openings. REDUCTION IN SUSPENDED MATTER. The results of in- dividual runs on slotted plates and average results for mesh screens of the nearest size are shown in table 91. The mesh screeiis were tested at a rate of 14,800 gal. per sq. ft. per 24 hr. to a final loss of head of 4.5 ft., whereas the slot screens were tested at a rate of 11,100 gal. per sq. ft. per 24 hr. to 1.5 ft. loss of head. TABLE 91. SLOTTED PLATE SCREENS. Percentage Reduction in Suspended Matter. Coarse Slots 1.00x0.0625 In. Medium Slots 0.50x0.032 In. Fine. . Slots 0.50x0.025 In. Susp. Mat. Parts Per Mil. Percent Reduc- tion Susp. Mat. Parts Per MU. Percent Reduc- tion Susp. Mat. Parts Per Mil. Percent Reduc- Infl. 1 Effl.. Infl. 1 Efil. Infl. 1 Efii. tion 420 356 15 370 298 19 394 312 21 528 424 20 370 270 27 390 316 19 364 336 8 478 366 23 459 316 31 393 360 8 364 288 21 652 404 38 397 372 6 403 324 20 170 144 15 477 376 21 344 268 22 316 240 24 512 432 16 353 308 13 364 292 20 535 444 17 409 348 15 Avg. 442 379 14 402 321 20 394 297 25 Avg. 520 No. 10 (0.72 In.) 470 10 MESH SCREENS No. 20 (0.034 In.) 695 585 16 No. 30 (0.022 In.) 747 596 20 The efficiency decreases with increasing width of slot, the small- est slots being most efficient. The average reduction in suspended matter appears to be greater than with screens of nearly corre- sponding opening operated under somewhat different conditions, even though the accumulation of screenings in pounds per million gallons was greater with the screens. The sewage was somewhat weaker during the summer of 1914 when the plate experiments 161 were carried on, than in 1913, when the first series was run on the screens. Hence, the proportion of coarse suspended matter may- have been relatively higher. Owing to the limited number and brief duration of runs, the results are not conclusive as to the com- parative merits of slotted plates and mesh screens. SCREENINGS. Ordinarily, after draining for a few minutes before weighing, the screenings contained from 80 to 90 per cent, of moisture, and resembled in every way the catch on the mesh screens. No analyses were made. The accumulation in lb. of dry material per mil. gal. for individual runs with average results for mesh screens of the nearest size (table 92) show slightly higher retentions for the mesh screens in the finer sizes. The average re- sults given for the No. 10 mesh screen are undoubtedly too low because two runs were unusually long. TABLE 92. AqCUMULATION OF DRY SCREENINGS. Pounds Per Million Gallons. Coarse 1 Medium Fine (0.0625 In. Slot) (0.032 In. Slot) (0.025 In. Slot) 535 600 680 866 836 618, 234 935 1190 271 - 635 2070 208 655 215 840 376 635 666 635 599 ••• 755 507 Avg. 517 678 814 Average for Screens of Nearest Corresponding Mesh No. 10 (0.072 In.) No. 20 (0.034 In.) No. 30 (0.022 In.) 421 919 1259 RESULTS. The results of these tests on slotted screens indicate that a considerable removal of suspended matter may be obtained with slots of the size used, which is probably somewhat lower than with screens of corresponding mesh. ADDITIONAL SCREENING EXPERIMENTS. GENERAL. Beside the loss of head, experiments made in 1913 on fine screens up to 40 meshes per lin. in., a few tests were made ill September and October, 1914, on screens of 60, 80 and 100 meshes to the. lin. in., in a manner similar to the previous sets, but 162 at a rate of 2940 gal. per sq. ft. per 24 hr., the final loss of head being 1.5 ft. The lower rate was employed to extend the runs sufS- ciently to give reasonably accurate measurements. RESULTS. The percentage removals based on computed analy- ses of the influent are shown below : PERCENTAGE REMOVAL OF SUSPENDED MATTER BY FINE MESH SCREENS. Meshes per Lin. Inch No. of Tests SUSP. Mat. P. P. M. Influent I Effluent Pbe Cent Reduction Susp. Mat. Average | Maximum | Minimum 100 6 345 244 29 45 18 80 5 300 200 33 36 24 60 6 328 251 23 34 14 In general, a higher ef&ciency is noted than with the screens of coarser mesh tested under somewhat different conditions. The dif- ference is not great, however. The sewage used in these tests was considerably lower in suspended matter than during the first series. The removal of dry material is indicated below in tabular form. REMOVAL OF MATERIAL BY FINE SCREENS. Meshes per Lin. Inch No. of Tests Screenings per Cent Moisture Pounds pek Million Gallons Moist Screen- ings Dry Screenings Average | Maximum | Minimum 100 80 60 84.3 86.6 87.4 6400 6370 4960 840 830 640 1400 1320 1135 676 386 290 The average pounds of dry suspended matter removed for all fine meshes is less than for the previous tests of a No. 16 screen with a stronger run of sewage and slightly different conditions of opera- tion. The percentage removals, however, were somewhat higher than reached by the No. 40 screen. The large difference in actual weight of dry material per million gallons is largely due to the difference in strength of the sewage, the suspended matter during the most recent tests averaging about one-half that for the first series. CONCLUSIONS. With the very fine mesh screens employed somewhat larger removals of suspended matter appear possible than with the 30 or 40 mesh. The difference does not appear very great. 163 CHAPTER XII. COMPARISON OF METHODS OF PRELIMINARY TREATMENT. GENERAL. Three distinct methods of tank treatment were tried during these investigations, — (1) plain sedimentation in tanks of the Dortmund or upward flow type; (2) plain sedimentation in the Imhoff type of double deck tank with a separate chamber for the retention and digestion of sludge; (3) chemical precipitation in Dortmund tanks. Extensive investigations on the value of fine screening as a preliminary process were also made. The grit cham- ber, although a part in the scheme of preliminary treatment, is not here considered a separate process, as the removal of suspended matter ordinarily is slight, serving as an adjunct to the subsequent tank treatment. REMOVAL OF SUSPENDED MATTER. As the reduction of suspended matter is the important point in all the processes just outlined, the percentage removals of suspended matter have been, summarized in table 93. The figures for the devices involving plain sedimentation are based on monthly averages of daily or bi-daily samples, the figures for chemical. precipitation for individual runs and the various screening experiments are for individual tests or runs. The reductions for both the plain sedimentation and chemical precipitation processes are given both for the day samples and for the entire 24 hours, although the precipitant was applied only for part of the day. The results of the screening tests are based on the computed influent analyses. Table 93 indicates that about 9 to 25 per cent., based on com- puted analyses of the suspended matter, may on the average be •removed by fine screening (30 or 40 mesh) with correspondingly smaller reductions for coarser sizes, depending on the hours when the screen is in operation. At individual plants, owing to greater concentration and freshness, of wastes, greater efficiencies may be expected. Plain sedimentation in either the Dortmund or Emscher type of tank will remove from 50 to 70 per cent, of the suspended matter, according to the methods of operation. "With chemical pre- cipitation of the heavy day sewage and plain sedimentation for the weak night flow, a removal approximating 80 per cent, has been attained. RETENTION OF SUSPENDED MATTER. Not only is the relative removal of suspended matter of moment in determining the efficiency of different settling devices, but the ability to retain the 164 TABLE 93. PERCENTAGE REMOVAL OF SUSPENDED MATTER BY VARIOUS DEVICES Percent Removal Period Veloc. Suspended Matter Device of Flow Hours Ft. per Hour Remabes Day 24-Hr. Samples Samples Dortmund Tank 10.0 1.0 80 72 4.0 1.1 69 65 3.0 1.5 69 65 6.0 1.7 63 57 2.0 1.8 49 42 1.9 2.3 54 53 4.0 2.6 54 48 1.0 4.5 49 47 Emscher Tank 4.0 1.9 52 45 3.0 2.5 50 47 2.0 3.8 51 48 1.5 5.0 53 50 1.9 9.2* 61 58 " Horizontal velocity. 2.9 6.0* 72 69 ' Horizontal velocity. Chem. Precip. 3.0 3.5 76 72 5.5 gr. copperas; 10.3 gr. lime 3.0 3.5 80 77 4.5 gr. copperas; 10.7 gr. lime 3.0 3.5 84 79 3.5 gr. copperas; 9.9 gr. lime 2.0 2.2 78 74 3.3 gr. copperas; 8.6 gr. Ume 2.0 2.2 67 68 3.5 gr. copperas; 5.1 gr. lime 4.0 2.6 79 70 3.5 gr. copperas; 5.1 gr. lime 4.0 2.6 82 74 2.4 gr. copperas; 5.2 gr. lime 4.0 2.6 72 65 5.2 gr. copperas; 5.5 gr. lime 6.0 1.7 77 4.9 gr. copperas; 6.0 gr. lime 4.0 2.6 64 52 2.4 gr. alum 2.8 gr. lime 4.0 2.6 73 66 3.0 gr. alum; 0.0 gr. lime 4.0 2.6 82 76 1.9 gr. alum; 2.7 gr. lim.e 4.0 2.6 80 76 3.2 gr. alum; 0.0 gr. lime Rotary Screen — - 30 mesh 17 8:00 A.M. to 4:00 P.M. 30 mesh 1'2 7:30 A. M. to 10:30 P. M. 30 mesh 9 8:00 A.M. to 11:00 P.M. . Fine Screens — 6 mesh 13 10 mesh 10 16 mesh 17 20 mesh 16. 24 mesh 21 30 mesh 20 40 mesh 26 Slotted Plates- Coarse 14 ^ Medium 20 Fine 25 NOTE. — Fine screen and slotted plate results are on special runs, not 24-hr., but short. 165 solid matter settled out is likewise important. In this respect the Emscher tank is desirable, since the design provides for automat- ically trapping the sludge to prevent it from being unloaded into the sewage again. During the ripening period and at times when the accumulation of sludge in the digestion chamber reached the level of the sludge ports, some unloading took place, bringing scum to the surface in considerable quantities. This, however^ is not a defect in principle, but an element of design to be provided for. Operation of tanks of the Dortmund type indicates that the sludge can in general be retained if the effluent channels are baf- flled and careful attention is paid to frequent cleaning. Frequency in cleaning is essential, especially during warm weather. However, the high temperature of the sewage combined with the larger organic content of the sludge all favor the rapid development of septic con- ditions with consequent tendency to unload. After the chemical precipitation tests were thoroughly started, it was found easier to retain the sludge than when the same tank was operated as a plain settling device. The formation of any dis- tinct scum was apparently prevented, except when alum was em- ployed. However, septic conditions develop with the chemically precipitated sludge, necessitating careful attention to cleaning. The practically complete absence of scum in this process, however, makes the retention of settled material considerably easier, than for plain settling. PERIOD ANDl VELOCITY OF FLOW. A comparatively short period of flow is sufficient for plain sedimentation in the Dortmund and Emscher tanks. With tanks of the upward flow or Dortmund type, vertical velocity appears to be more important than the de- tention period, for the highest removals of suspended matter were obtained at the lowest velocities irrespective of the detention period. However, with the same velocity, longer detention periods gave somewhat better results. Providing long periods of detention, in the Dortmund type of tank, is not economical, for with a vertical velocity of one or two feet an hour, which is most advantageous, and a period of say three hours, very shallow tanks result, which are practically straight flow tanks. An excessive number of units is also required. With higher velocities around 5 ft. per hr. and pe- riods of 1.5 to 3 hrs., the removal is much lower. The difficulty of maintaining low vertical velocities applies also to the radial flow type of Emscher tank. With the straight flow Emscher tank, thg indications are that a detention period of 2 to 3 hours is ample. AMOUNT OF SLUDGE. The volume of sludge and scum ac- 166 cumulated per million gallons was greatest for the chemical pre- cipitation treatment and lowest for the Dortmund tank C. The large amount of drier surface scum habitu3,lly present on Tank C explains in part the apparent inequality in rate of accumulation, as compared with the other tanks. Approximate average figures for various tanks are as follows : Apparatus Period of Flow Cu. Yd. of Sludge and Scum per Mil. Gal. TankC 1.9 to 4 hours 6.0 TankD 4 to 6 hours , 9.5 TankE 1.5 to 4 hours 8.0 Chemical Precipitation* 2 to 6 hours 13 . * 15 hours daily, plain sedimentation rest of day. The sludge from chemical precipitation considerably exceeds that resulting from plain sedimentation. The vigorous digestion going on in the Bmscher tank eliminates a portion of the sludge de- posited as gas, thus reducing the rate of accumulation. With the Dortmund tanks operating on a plain sedimentation basis, the rate of accumulation varies. The relative amounts of sludge and drier surface scum apparently influence the total volume markedly. The low yardage shown for tank C may be due to difficulties in manipulation. The sludge remaining in a tank after incomplete withdrawal is usually much thinner than originally. Hence the amount withdrawn calculated from measurements made before and after cleaning may be too low. Ultimately the thin sludge compacts to its former condition. The net result is to show a lower rate of ac- cumulation than was actually the case. Tank C was cleaned very frequently, tank B, least frequently. The true rate of accumulation, therefore, for tank C is probably higher than recorded. QUALITY OF SLUDGE. For drying on sludge beds, the Em- scher tank sludge proved superior. The entrained gases made the sludge light and porous, readily parting with a portion of its water, and drying comparatively quickly to a porous earthy mass, easily handled by spading. The chemical precipitation sludge, on the con- trary, was very sticky, requiring considerably longer periods for dry- ing, whereas the sludge from plain sedimentation in Dortmund tanks was intermediate between the two. All of the scums, although ini- tially drier than the sludges, were much harder to reduce to a spadeable condition, and were usually very offensive The well di- gested Emscher sludge showed a considerable loss of volatile mat- ter with a consequent reduction in calorific value. The fresh sludges 167 * from the Dortmund tank, if artificially dried, would contain consid- erably more thermal units. The fresh chemical precipitation sludge with a large content of inert mineral matter is low in heating value. SCUM FORMATION. Scum was consistently present on the Dortmund tanks at all times while operated on a plain sedimenta- tion basis, accumulating so rapidly that its removal became a prob- lem. Unless the formation can be prevented, it will prove trouble- some. Careful attention to the details of baffling will be of value, but will not wholly prevent the scum from passing off in the efflu- ent. Preliminary fine screening may remedy this difficulty, as tests to date indicate that it will afford some relief. The only difficulty from this cause in the operation of the Emscher tank appeared dur- ing the ripening period, and when the sludge chamber was excessive- ly full of sludge. The scums in general appeared to consist largely of light suspended materials of a fibrous nature, such as straw, chaff, hair, etc. In addition to the scum forming in the gas vent of the Emscher tank, a scum, somewhat different, consisting largely of grease has persisted on the surface of the settling chamber more or less regu- larly. The removal of the grease from the sewage appears to be the only cure. The chemical precipitation tank has been consistently free from scum. Small clots of the floe, with the lighter suspended matter entangled therein, appeared in limited quantities, but no continuous mat of scum has been recorded, except with the use of alum in place of copperas, when a heavy scum soon formed. ODOE. The question of odor may perhaps not appear so im- portant in this problem as ordinarily, since the general aerial nuis- ance from the Stockyards and Packingtown suffices to completely overwhelm any slight local odors which might come from the plant. On general principles, however, it is desirable to avoid odors so far as practicable. Of the different methods of tank treatment, the Emscher tank was on the whole the least open to criticism. The sludge, as dis- charged, had only a slight tarry odor, noticeable only a few inches away, although occasionally hydrogen sulphide was perceptible. At times, on top of the tank, a distinct odor was perceptible from the gas vent, particularly during the ripening period when the gas fun- nel was filled with scum, for then, when stirred, the scum had an offensive odor, distinctly containing hydrogen sulphide After ripen- iag, during the summer of 1913, this tank was in violent ebullition 168 continuously, but nothing more than a trace of hydrogen sulphide could be found. Comparatively little odor was noticed from the Dortmund tanks except when the surface scum was stirred up or when sludge was being discharged. In the latter case, in the vicinity of the tank an offensive putrid odor was frequently noticeable. The odor from the scums, especially when wet, was particularly offensive during removal. When operated as a chemical precipitation tank, the sludge from Tank D frequently had a peculiarly sweet sickish or metallic odor, decidedly offensive and entirely distinct from the other sludges. At times this was strong in the immediate vicinity of the tank. TABLE 94. AVERAGE MONTHLY TEMPERATURES OF CRUDE SEWAGE IN CENTER AVE. SEWER, AND VARIOUS EFFLUENTS. Date Average Monthly Temperature in Degrees Fahrenheit Airt Crude Sewage Grit Cham- ber Effluent Effluent Effluent Effluent Tank C Tank D Tank E Sprink- ling Filter Effluent Basin F Effluent Remarks 1912 Sept.*... Oct Nov. . . . Dec 1913 Jan Feb Mar. . . . Apr May. . . . June. . . . July Aug Sept. . . . Oct Nov. . . . Dec 59 59 43 33 29 25 35 49 58 71 75 74 65 53 47 37 85 80 70 66 65 62 60 67 75 84 87 89 86 77 73 70 84 80 70 68 65 62 61 68 75 84 87 89 86 77 73 70 86 88 84 76 72 69 82 77 68 67 64 60 58 66 73 83 86* 88 84 76 82 78- 67 65 63 60 58 62 73 83 86 88 84 76 71 69 57* 56 51 47* 50* 49* *15 days *i9 days *7 days *4 days *18 days *Part of' . month Avg. 1913 1914 Jan Feb Mar Apr May June July Aug 52 32 20 36 48 62 70 75 74 75 64 63 63 69 74 84 93 93 75 64 63 64 69 74 84 93 93 79 63 60 62 67 73 83 91 90 73 62 59 60 67 72 83 92 91 73' 64 62 61* 68 73 83 91 91 53 44 44 47* 55 64 71 78 78 49 45 44 48* 55 65 71 78 79 t U. S. Weather Bureau on Federal Building, Chicago. 169 The material removed by the rotary screen was entirely inodor- ous and inoffensive when fresh. After lying on the ground in thin layers for a few days, however, a very foul putrid odor developed in the under layers. OPERATION. Most of the details of operation were discussed indirectly under other headings, particularly the formation of scum, disposal of sludge, and details of cleaning. However, chemical pre- cipitation also involves constant attention to the application and control of the chemicals, as well as to the more complicated appa- ratus required / TEMPEEATURE. Ice formed upon the tanks, only when the surface layers of scum froze, the initially high temperature of the sewage preventing freezing, particularly as the drop in temperature in passing through the tanks rarely exceeded two degrees Fah. (Table 94). CONDITIONS OF FLOW. All results have been based on a uniform rate of flow through the tanks for the entire 24 hours. As a matter of fact the flow in the sewer fluctuates between wide limits at different times during the day. The bulk of sludge deposited in the tanks settles out during hours of heavy day flow, however, and if this is used as a basis for design, the rate of accumulation and neces- sary detention period should differ little from the results obtained at the uniform, rate. Analyses of the tank influents and effluents show that in general less than 10 per cent, of the total suspended matter deposited during the entire 24 hours settles out during the nine night hours. SETTLING EXPERIMENTS. To determine the settling char- acteristics of the sewage, tests were run under quiescent conditions in a manner similar to those first made at Cologne, Germany*, and , identical with those made at the 39th St. pumping station. The apparatus used in our experiments consisted of a cylindrical galvanized iron can 2 ft. in diameter and 9 ft. deep, fitted with taps and nipples projecting inside the can to the center so that the sam- ples drawn were taken from points in a vertical line. Crude sewage was admitted rapidly at the bottom, keeping the contents thoroughly stirred during the filling. The run was assumed to start on the com- pletion of filling. Samples were taken from each of the taps as soon as the can was filled, and a composite sample made to represent the crude sewage. The can was filled to a depth of 8 ft. 6 in. Samples were withdrawn for analysis 18 in. beloW the surface at the time in- *Mittheilungen aus der Koniglichen Prufungsanstalt fur Wasserversorgimg und Abwasserbeseitigung. Berlin, Heft. 4, pp. 40-45. 170 tervals indicated in table 95. The Cologne experiments were made in a vessel 15| in. square and 8 ft. 2^ in. deep, the contents being stirred with a paddle prior to the beginning of the run. The samples were collected from a tap 6 ft. 6f in. above the bottom, or 19f in. below the surface. The results of our tests (table 95) ifidicate marked reductions in total and volatile suspended matter. To make clearer the rela- tion between sedimentation time and percentage removal of sus- pended matter, the removals have been plotted (Fig 17), the results of the 39th St. experiments being added for comparison. As the available data on the Cologne experiments give only the removal of volatile matter, a second plot (Fig. 17), has been inserted, show- ing the percentage removals of volatile matter, including both the 39th St. and the Cologne experiments. To show the effect of varying amounts of suspended matter in the crude sewage, the results have been averaged and plotted by groups according to the initial sus- pended matter. With the weak 39th St. sewage, a substantial reduction takes place, both of total and volatile suspended matter, up to the 4th or 5th hour. With the very heavy Stockyards sewage, the reduction after two hours was slight, while the comparatively strong Cologne sewage deposited most of its settleable volatile matter within the- first two hours, although the increase in reduction for the next two or three hours was somewhat greater than for the Stockyards sewage. The quiescent experiments indicate that a removal of from 54 to 93 per cent, of the total material in suspension may be attained by 2 hr. quiescent settling, while at the end of 12 hr., the removal varied from 55 to 97 per cent., according to the original content of suspended matter. An average removal of 76 per cent, was attained at the end of 2 hr., while the removal at the end of 12 hr. averaged 79 per cent., which probably represents approximately the percent- age of settling solids. The removal at the end of two hours is ap- preciably better than in the tanks with the same theoretical deten- tion period, but the former results are raised by the inclusion of a number of tests from sewage much higher in suspended matter than the average throughout the day, and the percentage removals were correspondingly greater. With identically the same sewage, a slightly greater removal might occur under quiescent conditions. Samples taken at the end of 12 hr., at depths of 7 ft; in., 7 ft. 9 in. and 8 ft. 3 in., showed a considerably smaller decrease in sus- pended matter over the results obtained at depths of 18 in. and in some cases an actual increase was recorded. This simply indicates 171 IX! o I o iz; o I— I P < a H 03 13 O CQ H iz; S t— I 11^ a Q ^^ P. W<1 ■ O -!*< Oi CO Tt< Ttl ■ »o cc »o ■<*< 00 O P Iz; PL, OQ I-:; o Iz; o )— 1 H O Q S iz; o Ph OOOOOOOOlMTtti-loO 00CX)00t~00-*l>COl>^ t^cDCDI>CD0000(MO5(N i-ICClOOsastNO^DOOlO QOCO'*^— llOOOCO-HCTi CO^-^t-HCOt-KNCO"^ oooooooooo COC0(Mt>-lO00»O-^CDCO oscocDOOaoooooot^io OOOOCiOT-iOOiO>-H050 C0I>-»O-^a3(N00CDOi-H (M (N(M"-I i-IMi-H 0-ioco-*>-itoig 3 ^ 3 3 SS^^SS^"^^"" T-100t*COCD»O»OlO'^'^ T— t OOOOOlOOOOj-iOOlO June 27 25 July 2 June 23 July 9 8 16 11 June 30 July 11 loa 90 70 \ \ '^50 'ao 30 SO 172 Toto/ .Sc/spended Maf/ir 'Stock Yorc/s 'esofo /S30P/? *^.-37e3A &yC2 — "^3 7 — rv/p^ J.-. f/i-fAAttjU AThes^f^ f I' -^Sa^yI. ■tfoeJ TzeePf' Mjres / ^ ^"^ '^'^ -^0^ WoTs* 'Rmsi esfs ^^ / ^ ' SfocM yards s6oe/?/ n-/-Teat '■ "^ ^^ -r-^ r-pfii. rfeds r ° lb / f •/ / ^ --^ .^0- j-ga^ / ^<^ r fr' ° / /^ 1/ "•/" 1 / /„ WO l/o/o///e So3pene/e>oo5(N • ■ . ■ r-ootx)-*---- ■*>ot>,-i....^iot-t^co---- T-l---- rt-...l^ !-(•■•■ 1 • T-H T-H Pi ^ "3 O) M t^ 00 O Oi T-H CO CO 05 O CX) »-( C. r- H O i s^ ; -a s 2 S o g o c 'n S <1 CQ S 1 C gK CD »0 u! ::::::: :^ :::::::: 02 B ^ ?■■■■■■■■ i CL,- .J3 1 SEWAGE- 5.4 21.0 -19.2 23.7 Tt.OOiO P'<*<'*00CMOSO5C0CO OOOi-HCOlOCDCO 'Oi-H(MC0C0t-i^'*"-''— ''^'^'^^^ !1 1 g ^ .S iz; ^1 o CO »o ^c 05 t^ Ol Ol CO •* 05 -H 00 CO w IM CD CO CO CO W CO t> CO O .-1 0> Ol COIN(M(N "^3 O .S'S n ^ ?3?2§i52 tH 00 "* 05 t- 0> 00 00 O t> ffi (M 00 lO l?5 t> 0> ■* (N CO 05 OS 1> 00 H a C^ 1— I I-H T— 1 T— I T— I T-H rH I— i T-H T— I o 1 CO •CO o ■ o : o .(^ .o •S (^q .IN 1 g oc CO =3 en cc ;S CO :=3 CO = 3 5 3 35 :° 35 :° T-H a c > c a Sco 1 1 1—1 >l 1^ > 1— 1 2« >l '5 1 1-: < 2co fe§<: ■1 1- > 1 bii 176 TABLE 98. SPRINKLING FILTER. Removal of Suspended Matter. Date Suspended Matteb in Pabts per Million Influentft Tot. VoL Fixed Effluent Tot. Vol. Fixed Per Cent Reduction , Tot. Vol. Fixed Remarks 1913 Sept.22to30 October . . November Dec. 1 to 18 1914 Jan. 3 to 31 February . Mar. 1 to 9; 20 to 31 April May June July Aug 1913 Sept.22to30 October. . . . November . Dec. 1 to 18. 1914 Jan. 3 to 31 . February. . . Mar. 1 to 9; 20 to 31. April DAY SAMPLES-SUNDAYS OMITTED. 258 210 48 98 66 32 64 69 33 248 184 64 321 146 175 29* 21 174* 262 205 57 144 99 45 45 52 21 276 231 45 135 103 32 51 55 29 228 180 48 109 71 38 52 61 21 193 154 39 122 88 34 37 43 13 173 147 26 117 80 37 32 46 42* 137 111 26 208 148 60 52* 33* 131* 156 140 10 112 99 12 107 81 24 83 73 12 Filter un- loading May. June. July. Aug. . NIGHT SAMPLES— SUNDAYS INCLUDED, IN 1913. 88 74 14 233 128 105 163* 73* 650* 84 63 21 318 136 182 279* 116* 767* 98 69 29 137 88 49 40* 28* 69* 95 66 29 105 72 33 10* 9* 14* 86 63 23 63 44 19 27 30 17 52 39 13 69 52 17 33* 33* 31* 89 70 19 120 77 43 35* 10* 126* 51 38 13 158 111 47 210* 192* 261* 58t 115t 98* 67 72 20* 53 74 40* 43 64 59* Filter un- loading fTen days only 1913 DAY AND NIGHT (24 Hours) SEWAGE— SUNDAYS OMITTED. Sept.22to30 October. . November Dec. ltol8. 1914 Jan. 3 to 31 . February . . Mar. 1 to 9; 20 to 31 April May. June. July. Aug. . 197 196 204 210 164 141 141 104 125t 92 87 68 163 144 158 171 127 111 116 83 34 45 46 39 37 30 25 21 148 319 147 124 90 104 121 183 123t 86 78 70 89 142 99 91 59 75 79 132 59 177 48 33 31 29 42 51 25 63* 28 41 45 26 14 76* 2 7 11 3* 1 37 47 54 32 59* 42. 293* 4* 15 16 3 68* 143* Filter un- loading tlO days only * Denotes increase. tt Emscher tank effluent. 177 day, night and 24-hr. samples. The effluent has been consistently- high in suspended" matter, especially in October, 1913, the percent- age reduction on the 24-hr. samples ranging from an increase of 76 per cent, to a decrease of 45 per cent. The increase in October, 1913, was doubtless due to the washing out of the residual dust adhering to the filtering medium, as the increase is entirely in the fixed mat- ter. During the unloading period in April,' 1914, the filter also was discharging more suspended matter than it received. In the filter effluent was contained considerable suspended mat- ter of a different character, however, from that in the influent, being fine, granular, and settling in the sample bottles with comparative rapidity. Mineralization of the suspended matter applied to the filter occurred to a coiisiderable eixtent, as evidenced by the marked- ly higher proportion of fixed matter in the effluent and the lower percentage reduction in this constituent than in the volatile sus- pended matter. So far, the filter has stored less than 20 per cent, of the applied suspended material based on the chemical analyses of influent and effluent. Marked unloading occurred in April, 1914, a large increase in suspended- matter over that applied being noted. NITRIFICATION. A high degree of nitrification was quickly established, the nitrates in the effluent rising to 17.3 p. p. m. on Oct. 2, 1913, 10 days after the filter was placed in operation. Table 97 shows the monthly averages for nitrates in effluent. Ordinarily the Bmscher tank effluent contains from 1^ to 4 p. p, m. of nitrates. The filter effluent has averaged about 17 p. p. m. on the day samples; after the first few days of operation. With the large increase in nitrates, a corresponding reduction in organic nitrogen, ranging from 60 to 77 per cent, occurred. A high reduction in oxygen con- sumed likewise is noted (Tables 38 and 97) PUTRBSCIBILITY. Samples for putreseibility were taken four times daily, at 3 A. M., 9 A. M., 3 P. M., and 9 P. M., being in- cubated for ten days at 20 deg. C, with the addition of methylene blue in 150 c.c, equivalent to 0.4 c. c. of a 0.05 per cent, aqueous solution. Twenty days was originally adopted as the incubation period, but it was found that samples not decolorized at the end of 10 days might, for all practical purposes, be considered stable The average results by months are shown in Table 99. Relative stability figures are shown in Table 100. These are computed from the Phelps tables, except that samples holding out for 10 days have been given a relative stability of 100. The 3 A. M. and 9 A. M. samples represent the weak night sew- age, while the 3 P. M. and 9 P. M. samples represent the strong day sewage.. 178 TABLE 99. SPRINKLING FILTER. Results of Putrescibility Tests on Filter Effluent. Number of Samples Per Cent Putbescible Date 3 A.M. 9 A.M. 3 . P.M. 9 P.M. Total 10-Day Basis 4-Day 3 A.M. 9 A.M. 3 P.M. 9 P.M. Total Total 1913 Sept. 22 to 30. . . October . . Nov Dec. 1 to 18 1914 Jan. 3 to 31 Feb Mar. 1 to 9; 20 to 31 April May .... June .... July Aug 1 25 21 11 22 15 11 24 24 25 22 25 2 24 24 13 24 18 15 24 23 22 23 22 2 26 23 16 23 17 11 25 23 24 24 26 , 2 24 24 13 23 15 12 23 22 25 24 25 7 99 92 53 92 65 49 96 92 96 93 98 68 62 45 95 67 36 79 4 8 5 48 46 16 54 \ 92 39 20 46 17 18 13 36 50 81 43 50 96 88 36 64 13 13 25 42 100 54 63 69 91 80 33 65 27 12 4 4 43 63 46 55 93 60 31 64 15 12 12 33 29 47 39 43 88 45 20 51 8 6 3 21 On the whole, there is little choice between day and night re- sults in percentage of putrescible samples and relative stability. To date, about 35 per cent, of the 9 A. M. samples have been putrescible on the 10 day incubation basis, while for the other three sampling periods, the proportion of putrescible samples in each case has alver- aged close to 50 per cent. The better showing of the 9 A. M. samples is probably due to collection from the very end of the weak night flow when the filter had the longest opportunity to recover from the heavy day load, the effect of which apparently extends into the night, no appreciable improvement being noted at 3 A. M. Consid- ering all samples collected in the course of the day, the percentage . of putrescible samples thus far has averaged slightly under 50, with a relative stability averaging nearly 75. To correspond with the putrescibility tests, made at 39th St. to date, based on a 4 day in- cubation period, a column is inserted, giving the percentage of sam- ples putrescible after 4 days. Under this less rigid test, the per- centage of putrescible samples is considerably smaller, the decrease for individual months varying from 5 to 16 per cent. Tests for biologic oxygen consumed (see chap. XV) show rela- tive stability results in the later months even better than the 179 methylene blue test would indicate, practical stability having been attained. DISSOLVED OXYGEN. Samples for the determination of dis- solved oxygen were taken simultaneously with the putrescibility samples. The results, sumnjarized by months in table 101, show that, practically at all times, the filter effluent contained a considerable amount of dissolved oxygen. TABLE 100. SPRINKLING FILTER. Relative Stability of Filter Effluent. Monthly Averages. Date ReijAtive Stability Number 3 A.M. I 9 A.M. I 3 P.M. | 9 P.M. | Average Remarks 1913 October. 55 November 52 .Dec. 1 to 18 62 1914 Jan. 3 to 31 25 Feb. 1 to 8; 16 to 28. 82 Mar. 1 to 9; 20 to 31 76 April 51 May 99 June 96 July 98 Aug 70 77 88 82 40 83 88 76 86 92 97 85 56 79 80 36 63 83 65 92 96 92 80 56 71 31 56 83 60 88 94 98 95 64 70 74 33 71 82 63 92 94 96 83 Unloading. Note: Samples folding out 10 days assumed to have relative stability of 100. TABLE 101. SPRINKLING FILTER. Dissolved Oxygen in Filter Effluent. Dissolved Oxygen — Parts per Mil. Date 3 A.M. I 9 A.M. I 3 P.M. | 9 P.M. | Average. Per Cent Sat. 1913 •Sfept. 22 to 30 7.6 9.4 8.0 7.7 8.2 78 October 5.1 8.2 7.5 4.1 6.2 55 November 5.1 8.2 7.5 4.1 6.2 55 Dec. 1 to 18 5.8 7.9 7.5 5.0 6.4 54 1914 Jan. 3 to 31 3.0 6.4 3.7 4.8 4.2 4.8 3.5 2.8 3.6 4.8 29 February. 39 Mar. 1 to 9; 20 to 31 . 5.5 5.4 4.0 3.4 4.6 40 April 3.7 3.9 3.3 2.8 3.4 32 May 4.4 3.2 3.7 2.4 3.4 35 June 5.6 5.4 4.9 4.5 5.1 56 July 5.6 5.2 4.9 5.4 5.2 63 Aug 5.4 5.0 4.6 4.5 4.9 59 180 NOZZLE CLOGGING. The nozzle was protected hy a screen made of common wire window screening, with 12 meshes to the lineal inch, placed in the orifice box Being operated with the orifice wide open, the tendency for clogging was minimized. Under these circumstances, the nozzle required comparatively little attention. Such clogging as occurred was caused largely by small balls of grease, probably formed as the sewage cooled ia its flow to the filter as well as by detached pieces of fungous growths from the supply pipe. During the spring the loss of capacity of the pipe, due to growths, made cleaning necessary to maintain the spray at the outer edges of the filter. Occasionally, long thin particles of solid material such as bits of straw, etc., passed the screen and resulted in clogging. BIOLOGICAL LIFE. Numbers of smair white moth; flies ap- peared soon after the filter started, hovering about the edges of the spray, but not leaving the immediate vicinity of the filter. With the approach of cold weather, they disappeared, except for a few warm days during the late fall, and reappeared in the spring They were • not present to any marked extent during the summer of 1914. Dur-- ing the unloading p'eriod in April, very fine white worms became numerous in the filter effluent, large red worms being also found in the secondary basin sludge. Shortly after the filter started, a brown, bacterial slime began to form on the surface stones, soon covering the whole surface of the filter, and persisted through the cold weather. At intervals, patches of the growth became detached from the stones, but these were promptly renewed. ODOR. A distinct odor was perceptible in the immediate vi- cinity of the filter, resembling the odor from decayed vegetables. The scum and sludge removed from the secondary settling basin had the same odor. In a large installation, the open filters might pro- duce an odor of sufficient intensity to require thorough precautions to avoid nuisance in the immediate vicinity. TEMPERATURE AND ICE FORMATION. The filter ran throughout the winter, although a heavy ring of ice formed around the edges of the spray. Otherwise the surface was always open, except during protracted shut-downs, when a thin- coating of ice sometimes formed. The high temperature of the sewage will un- doubtedly prevent any trouble with ice on open filters. APPEARANCE OF EFFLUENT. The effluent was almost uni- formly free from turbidity. The suspended matter unloaded was coarse, granular, and quick settling. 181 SURFACE CLOGGING. No surface clogging of any conse- quence was noted. Before the unloading period in April, the sewage was slow to disappear at a few spots, but thereafter this condition entirely disappeared. Raking of the surface stones also helped. EFFECT OF DEPTH AND SIZE OF STONE. The effect of variations in depth and size of stone was not studied. "With a total depth of six feet, good results were obtained with the li to 2-in. stone. Presumably, greater depths would give an efSuent of some- what better quality. Although no clogging of note has occurred thus far, it is pos- sible that somewhat larger stone .would facilitate the unloading of the lajrge quantities' of solid matter stored in the filter at times. The question of grease retention also is important, although up ' to date no difficulty has occurred. If larger stone is used, some increase in depth might be warranted. GROWTHS 'IN PIPES. A black^^slimy fungous growth accu- mulated quickly; in the' supply pipe, sometinles attaining a thickness of ^ in. seriously impairing "the capacity of the pipe and making fre- quent cleanings necessary to maintain sufficient head on the filter nozzle. This suggests the value of ready accessibility in the dis- tribution of sewage and tank effluents. The formatibn of a slimy scum was also noticed in the open wooden troughs supplying the tanks. SECONDARY SETTLING BASIN. REMOVAL lOF SPSPENDBD MATTER. Table 102 shows the percentage! of suspended matter iremoved by the secondary settling basin, while uniformly operated with a detention period of from 1.0 to 1.5 hours, with a vertical velocity varying from 2.4 ft. per hr. to 3.5jft. per hr. , The removal of suspended matter was smaller than is desirable or attainable, considering the nature of the material in suspension. A lower velocity and longer detention period are ap- parently desirable. , , , Scum, especially ! during the warmer months, has frequently appeared. 'A tank o:^ the Emscher type Would fetain the settling material arid obviate most if not hll of > the scum. PUTRESCIBILITY AND DISSOLVED OXYGEN. Samples for putrescibility (table 103) and dissolved oxygen determinations were taken 4 times daily, corresponding to the filter samples with allowance for the detention period in the basin. Relative stability figures are shown in table 103a. 182 The results of the dissolved oxygen tests (table 104) are prac- tically the same as for the filter, a slight dimiriution in oxygen oc- curring through the tank.- TABLE 102. SPRINKLING FILTER. Removal of Suspended Matter by Secondary Settling Basin. Date 1913-14 Suspended Matter — Pabts pee Mil. Influent Total Vol. Fixed Effluent Total Vol. Fixed Per Cent Reduction Total Vol. Fixed Period of Flow Hr. Up- ward Vel. Ft.per Hr. Dec. 4-18 137 110 27 90 73 Jan. 3-31. 109 71 38 63 45 Feb 122 88 34 112 77 Mar. 1-9; 20-31.. 120 82 38 53 41 April 208 148 60 99 74 May 126t 72.t June 99 108 July 1-22 90 76 " 22-31 65 60 Aug 73 33 DAY SEWAGE. 17 18 35 12 25 34 41 8 56 52 43t 9* 16 8 55 34 37 12 50 50 37 63 3* 68 58 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.5 1.3 2.4 2.4 2.4 2.4 3.5 3.5 3.5 3.5 2.4 2.7 NIGHT SEWAGE. Dec. 4-18 Jan. 3-31 Feb. Mai. 1-9; 20-31.. April. May June. , July 1-22 July 22-31 Aug. Dec. 4^18 Jan. 3-31 Feb Mar. 1-9; 20-31 April. . . May. . . June. . . July 1-22 July 22-31 Aug 94 65 29 76 51 25 19 22 14 1.0 ?. 4 63 44 19 41 29 12 35 34 37 1.0 ?, 4 69 52 17 49 38 11 29 27 35 1.0 2.4 120 77 43 121 75 46 1* 3 7* 1.0 ?. 4 158 111 74 86 61 25 46 45 64 1.0 3 5 109t 63t 42 1.0 3 5 72 60 17 1.0 3 5 75 59 21 1.0 3 5 72 . , 33 54 1.5 ?, 4 64 HA .Y AN 32 D NIG HT SI :WAG] 50 D (24 I lour). 1.3 2.7 125 95 30 84 62 22 32 35 27 1.0 9. 4 90 59 31 53 37 16 41 37 48 1.0 2 4 104 75 29 90 62 28 14 "17 4 1.0 2.4 126 82 44 83 56 27 34 32 39 1.0 9. 4 183 132 51 85 62 23 54 53 55 1.0 3 5 115t 65t 44t 1.0 3 3 86 92 7* 1.0 3 5 84 70 17 1.0 3 5 67 50 25 1.5 ?, 4 70 33 53 1.3 2.7 * Denotes increase, t Part of month only. 183 SLUDGE. Table 105. gives the rate of sludge accumulation, varying considerably between individual measurements. Little scum appeared during cold weather, unless the flow was shut off for some time. With the approach of warm weather, scum formation became excessive, comparatively little sludge being retained in the bottom of the tank. TABLE 103a. SPRINKLING FILTER. Relative Stability of Secondary Settling Basin Effluent. Monthly Averages. Date Relative Stability Number 4 A. M. 10 A. M. 4 P. M. 10 P. M. Average Remarks 1913 Nov 100 100 100 100 100 Dec 74 78 85 69 76 1914 Jan 36 42 30 34 35 Feb 78 79 63 47 67 Mar 65 87 84 78 79 Apr 62 89 77 59 69 May 96 93 92 91 93 June 100 97 93 91 95 July 100 98 94 97 98 Aug 89 80 80 94 86 Note. — Samples holding out 10 days are assumed to have relative stabil- ity of 100. The sludge was uniformly of a dark brown color, of smooth consistency, with an odor resembling that of decayed vegetables. Typical analyses (table 106) ^how a comparatively large content of nitrogen, low fats, and a decreased percentage of volatile matter compared with fresh sludges. During the spring, the sludge re- moved from the tank contained numerous fine white worms. 184 TABLE 103 sp:^inkling filter. Showing Results of Putrescibility Tests on Secondary Settling Basin Effluent. Number of Samples Per Cent Putebsoiblb Date 4 A.M. 10 A.M. 4 P.M. 10 P.M. Total 4 A.M. 10 P.M. 4 P.M. 10 P.M. Total Total (4 days) 1913 Nov.26-30 Dec. 1-18 1914 Jan. 3-31. Feb Mar. 1-9; 20-31.. Apr May June July Aug 4 10 21 16 10 24 21. 24 23 25 4 11 23 17 12 22 18 21 22 20 4 12 23 16 12 24 20 24 23 26 4 13 23 15 10 23 21 24 24 25 16 46 90 64 44 93 80 93 92 96 50 86 38 50 71 10 28 36 87 35 17 18 17 10 5 40 42 100 69 25 46 20 21 9 27 69 91 93 50 65 14 25 4 8 55 91 58 34 51 15 15 4 25 36 88 52 27 43 10 3 2 17 TABLE 104. SPRINKLING FILTER. Dissolved Oxygen in Secondary Settling Basin Effluent. Date 1913 Nov. 26 to 30 Dec. 1 to 18 . . Dissolved Oxygen — Parts per Mil. 4 A.M. I 10 A.M. I 4 P.M. | 10 P.M. | Average 8.1 5.2 1914 • Jan. 3 to 31 2.7 February 6.6 Mar. 1 to 9; 20 to 31... 3.5 April -. 2.7 May 4.6 June 5.2 July 5.0 Aug 4.6 8.4 6.2 3.3 4.4 4.3 4.2 2.9 4.5 4.5 4.6 8.1 6.4 4.1 3.8 1.9 2.9 2.6 4.6 4.6 4.4 8.6 5.5 3.5 3.3 3.5 2.4 2.6 4.1 4.9 4.3 8.3 5.8 3.4 4.5 3.4 3.0 3.2 4.6 5.0 4.5 Per Cent Satura- tion 73 56 28 37 29 28 36 51 61 54 Remarks 185 03 n g ■ o ^ 1 >Tj a M § Ph I, ■a 3 I ^5 S ■3 O 12; o ^ n B O I I 'm 3 PS" 1 ^ d 'oci ■a 3 OS 02 m -O ■ O -O • 3 • oJ5 • ^* ^ ^ ^^ ^ ^ Tji • (N (N (N (N 0 U5 to IC U3 • CO CO CO CO CO M CO •ooooooo oooooooo • lo CO o as t~ CO OS • o rH (N N eOIN-*1> (N'^COtdcOCOi-ICO ■OOOOOOO ooooooo • lO CO (N (N 00 CO ^- t~O00-*«DiH«3O •OtH-^'»OC^i^'t* N'^COOOCOt-It-i • l£5 (N Cfl -^ 00 "3 t* t^ O CO -^ 00 i-t «3 W3 ■OCO-^*COCOtO •OCO-^COC^*»Ol>hSc million, and that of other domestic sewages, the fat in the day sewage, espe- cially during the heaviest hours, is very high, although much lower in the night flow. Some seasonal variation undoubtedly occurs. The eare in operating the skimming basins in the packing houses, as well as the kill, has an influence. The fat appears in a scum on the surface of the grit chamber in cold weather, and on Bubbly Creek at all times. The scum forms largely by chilling, when the hot sewage comes in contact with the cooler air or river water. Animal fat is essentially a mixture of stearine, palmitine and olein. The first two are solid at ordinary temperatures, having melt- ing points of about 160 deg. and 150 deg. Fah., respectively. Olein is a liquid with a melting point of 23 deg. Fah. The melting point of a so-called fat or grease depends upon the relative proportions ia the mixture of these three Constituents. In September, 1913, the ether extract from the grit chamber scum had a melting point of about 79 deg. Fah. Since the temperature of the sewage during the warm months is above 79 deg. (Fig. 10), the tendency to congeal and rise as scum is largely lost. "With cold weather, the accumu- lation of scum increases (table 20). The scum accumulating on the river continues during the summer, however, probably because of the chilling effect of the colder river water, seldom over 70 deg. Fah. The amount of fat recoverable in this way has led several packers to maintain skimming plants at the Ashland Ave. and Center Ave. outlets. REMOVAL OF FAT BY VARIOUS DEVICES. Although scum is removed in large quantities from the surface of the grit chamber 188 o O w H M '- 02 u GO o I— ( H E-i H O 1-3 i pC4 / "So 1 .S.2" (M to l> O ■* 05 M o: CO CO § S t*CVDO"3»- 00 1-H T— 1 tH tA §^ O •^ ' ■05 to I> l> t^ - •^ . •§:&§ O 00 IN 1> CO t~ Oi ^ CD 1 COl>t--*00tOtOfcO to . "§ n — lcOtO-*iffl(NtO>0 t~ ■fir'* TiHlOlOlOtO-^IM-* ■* H >oE-i 1 Of p:> S fS 1>000>001>-(NOO lO U3 lO to l> >* CO -^ lO •3 . .g.o. 00 to Ol OS 00 I> CO 1-1 CO «l-*-*tOtN-*«)05 lO 6^ "5 §2 1 1 cDcqososooccooco CO 00 OS 1> lO lO 00 o o 1—1 1—1 00 03 Hi Q S3 ^ §3 u5 '^ lo lo o in lo 1- T-( B b eo o t- >* lO t~ lo OS t> H^ SH »-tTH (5 H 1 1'a ^ssssg^i fe "1 1— l(Ni— iVHi— li— (i— li— 1 1—1 IN -♦ p cq s ^s & s^' cc s ■ S3S3SSSS S?3^S?5^S2 a 1 ^ 1 < ' 1 ' < 189 during cold weather, the amount of fat actually skimmed is only about 11 per cent, of the total fat in the sewage, as indicated by a series of tests on the day sewage covering one week in March, 1914. During the warmer months of the year, when little or no scum forms, a smaller recovery occurs. The amount of fat removed from the day sewage (grit chamber efSuent) by the various tanks is shown on table 107. The Emscher and Dortmund tanks removed approximately 50 per cent., which is equivalent to between 600 and 700 lbs. per mil. gal. Some change, in rates and velocities of flow were made during the period covered by these tests. With chemical precipitation treatment, the, removal averaged 66 per cent., corresponding to a retention of about 900 lbs. per mil. gal. This may be due to. the more complete precipi- tation of suspended solids and to the formation of insoluble lime soaps which are dragged down by the precipitant. The results (table 108) for the Emscher tank and the sprinkling filter show that on an average about 50 per cent, of the grease leav- ing the grit chamber was retained by the tank while nearly 20 per cent, was caught in the filter, or approximately 225 lbs. per mil. gal. The chilling of the sewage by spraying probably causes the removal. As yet, there is doubt whether this grease is permanently retained in the interstices of the filter or whether it is unloaded wholly or TABLE 108. REMOVAL OF ETHER SOLUBLE MATTER IN SPRINKLING FILTER. Day Sewage 8 A. M. to 10 P. M. Date 1914 Ethek Soluble Pakts per Million Pee Cent Reduction Pounds Retained Pee Mil. Gal. Grit Cham- ber Em- scher Tank Sprink- ling Filter Em- scher Tank Sprink- ling FUter Total Em- scher Tank Sprink- Ung Filter Total Mar. 20 to 21 23 to 24 25 to 26 Apr. 20 to 25 27 to May 2 May 4 to 9 11 to 16 18 to 23 June 15 to 16 24 to 25 July 3 to 4 145 208 178 129 165 142 145 186 161 150 119 135 104 75 45 50 75 55 97 74 70 85 29 24 24 46 46 45 32 86 46 28 26 7 50 58 65 70 47 62 48 54 53 19 73 38 29 1* 2 21 16 6 17 28 59 80 88 87 64 72 68 78 54 71 81 78 84 868 860 701 960 670 751 743 726 667 284 885 668 425 8* 33 250 192 92 250 350 492 969 1536 1285 693 993 920 943 835 976 1017 776 Average. . . . , 156 72 45 54 17 71 700 225 925 * Denotes increase. 190 in part. If retained, a progressive diminution in capacity may end in complete stoppage of the voids. No evidence of such clogging has as yet appeared. A sample of the slime scraped from the stones just below the surface of the bed showed an ether soluble content of 7.6 per cent. Tests lasting one week in March, 1914, showed the removal of residual fat by the secondary settling basin to be com- paratively insignificant. FAT IN SLUDGES. The fat removed from the sewage in the tanks should appear either in the sludge or scum. Routine analyses of sludges and scums were shown in tables of sludge and scum anal- yses in previous chapters. In general from 5 to 10 per cent, of the dry residue in the bottom sludge is ether soluble material, whereas the scums have averaged as high as 20 per cent., and the thin greasy scum, frequently appearing on the surface of the settling compart- ment of the Emscher tank, has contained as high as 50 per cent. The routine sludge and scum analyses were all made by simple ether extraction without first acidifying the sample, and do not in- clude the fats combined as soaps. A few random analyses, following, indicate that the total fat obtained after acidification may consid- erably exceed the amount usually determined. COMPARISON OF ETHER SOLUBLE MATERIAL IN ACIDIFIED AND NON- ACIDIFIED SAMPLES. Tank Material Ether Soluble Percentage of Dry Weight Remarks Not Acidified | Acidified C D Scum Sludge Sludge Scum Scum 11.4 23.3 7.4 10.0 10.0 23.6 62.3 69.0 12.6 29.8 Chemical Precipitation C Grit Chamber E From gas vent RECOVERY OF GREASE. Various experimentors have tried to recover the grease contained in sewage, but as a rule without success, largely because the cost of recovery is high, compared with the value of the products recovered. Ordinarily, the attempts have /been confined to the sludge produced by sedimentation processes. The high content of water is apparently the chief obstacle to success, as drying by mechanical means or by heat is usually required. The most notable instance of grease recovery probably is at Bradford, Bng., where large quantities of wool washing wastes are discharged. The sewage averages about 440 p. p. m. of fat. The 191 sludge is treated with' sulphuric acid, heated to 212 deg. Fah. and pressed. The grease passes ofE with the hot press liquor and is sub- sequently separated in tanks and further treated with chemicals. In 1907 a slight Jtrofit was reported, but as certain salaries, interest and sinking fund charges were not included, this profit may be ap- parent rather than real. At Cassel, Germany, the sludge was pressed and the sludge cake dried and disintegrated with steam. The grease was separated by extraction with benzine and recovered by steam which was afterwards condensed and the grease separated. Not- withstanding the sale of fertilizer and grease, the process proved Uneconomical. Attempts to treat wet sludge at Frankfort, Germany, with benzine proved too costly to be considered, although the dried sludge residue contained from 15 to 20 per cent, of grease. At Oldham, Eng., it is proposed to treat the sludge with a small amount of acid and superheated steam in retorts. The grease will subsequently be recovered by condensation. Experiments recently made in Boston, Mass., have indicated that treatment of the raw sewage by sulphur dioxide gas, produced by the burning of pyrites, facilitates the separation of fats to a marked extent. The cost of acidification in this manner is claimed to be slight as compared with the use of sulphuric acid. By drying the sludge and extracting the fat with some solvent, Mr. G. W. Miles claims that a profit can be realized from the sale of grease and fer- tilizer. The process has not as yet passed the experimental state, however, and has not been tried on a working scale. The general conclusion elsewhere is that past attempts to re- cover grease on domestic sewages have not been profitable and that on industrial wastes a profit is seldom shown. However, a way may eventually be found to reduce the cost of sludge disposal by recovery of grease and fertilizer material, rather than as a commercial under- taking for profit. ACID EXPERIMENTS. GENERAL. The "cracking" or acidification of sewage to re- move fat is used in many industrial plants, particularly on wool washing wastes. To learn whether, acidification could increase the yield of fat from the Center Ave. sewage, tests were made in barrels and on a larger scale. In two preliminary tests, made in barrels each holding about 40 gal. of sewage, sulphuric acid was added to distinct acidification, the liquid being settled for 3 hr. under quiescent con- ditions. In the first experiment, the suspended matter was reduced from 684 to 26 p. p. m. and the fat from 250 to 52, a reduction of 79 per cent. In the second experiment, the suspended matter was 192 decreased from 596 to 20 p. p. m. and the fat from 288 to 69 p. p. m., a reduction of 76 per cent. The supernatent liquid, at the end of the sedimentation period^ was, in both cases remarkably clear. TANK TREATMENT. Large scale tests were made in Tank C. Commercial acid (66 deg. Be. or 93.5 per cent.), diluted sufficiently to facilitate control by a small glass orifice with constant head over- flow, was applied to the sewage in the influent trough a few feet before entering the tank between 8 A. M. and 11 P. M. The first results directly after the start on Aug. 11, 1914, were discarded, as acid was not added in sufficient amount to neutralize the alkalinity of the sewage. The results given are subsequent to Aug. 24. So far as possible, an amount of acid was added to acidify the tank effluent, but this result was not always attained. The average rate of application was about 3,200 lb. of 100 per cent, acid per mil. gal., equivalent to about 22.4 gr. per gal. To neutralize the average alka- linity of the day sewage, 300 p. p. m., calculated as CaCO^, theo- retically requires about 2,500 lb. per mil. gal. of acid. The rate of application was below this figure at tiraes, and the alkalinity ex- ceeded the average at other times. The tank was operated on a 3-hr. period of sedimentation, acid being applied on an average for 14 hr. daily. TABLE 109. ACID TREATMENT OF DAY SEWAGE AT CENTER AVE. AVERAGE RESULTS IN SUMMER, 1914. Determination No. of Days Parts per Million Grit Chamber Effluent Tank Effluent Per Cent Reduction Nitrogen as Org. N 18 Free Amm 18 Nitrites 18 Nitrates 18 Chlorine 20 Oxygen Consumed 20 Suspended Matter Total 16 Volatile 16 Fixed 16 Alkalinity 20 Fats 14 61 41 33 20 20 0.37 0.09 76 2,38 2.04 14 1000 169 1000 119 30 385 306 79 112 96 16 71 69 80 260 -46 135 42 69 193 RESULTS OBTAINED. The average results available to date (table 109) indicate that acid treatment materially affects only the fat, by producing a higher recovery of fat, namely an average of 69 per cent, as compared with 47 per cent, for the period on which figures are available on a plain sedimentation basis (table 107). The latter average was secured under somewhat different conditions of operation. The fat removal is lower than that observed in the bar- rel experiments. A considerably higher reduction in fats was also noted as a result of chemical precipitation treatment. This very likely was due to the formation of insoluble lime soaps with the ex- cess lime which afterwards settled out. From the standpoint of oxy- gen demand, an apparent improvement was noted ia both tank and barrel experiments, as follows : Device No. of Days Tested Biologic Oxygen Consumption. P. P.M. Per Cent Reduction B. O. C. Settling Period Hr. Grit Chamber 7 915 Acid Tank (C) 7 294 68 3.0 Chem. Pre. Tank (D) 6- 505 33 4.0 Emscher Tank (E) 7 552 40 3.0 In obtaining the oxygen demand, the acid effluent was neutral- ized with sodium bicarbonate and inoculated with a few drops of grit chamber effluent. The results apparently are better than those for the other tanks (table 111). Possibly this is due to the more com- plete removal of colloidal matter in the acid treatment. Probably the better results are apparent rather than real and are due to the sterilization of the bacteria originally present and the retardation of subsequent decomposition, under conditions of test. The organic, matter present when discharged into a stream and thoroughly inocu- lated, would undoubtedly produce results of a liquid more unstable. When acid was added, scum formed comparatively slowly, the surface of the tank remaining free from one to two weeks after cleaning. Eventually scum appeared, however. The average rate of accumulation in cu. yd. per mil. gal. was 5.1 for the sludge and 2.0 for the scum. The sludge flowing from the tank was then a dirty yellowish gray color. The scum also was thin and foul in odor. Typical analyses are given on the following page . Compared with sludges derived from other treatments, the fat content is apparently very high. But as the routine analyses were made without acidifying the sample, the difference is less than ap- 194 ACID TREATMENT OF SEWAGE. Analyses of Sludge and Scum. Date 1914 Specific Gravity Per Cent Mois- ture DiiT Weight — Percentage Remarka Nitro- gen Volatile Matter Fixed Matter Ether Soluble Aug. 18 24 24 1.02 1.02 1.01 94.0 95.8 88.2 2.74 76 24 22.3 3.12 88 12 25.3 3.64 81 19 26.3 Sludge Sludge Scum pears, and reference to the results on page 190 indicates that the difference in many cases is very slight. COST. With an average alkalinity of 300 p. p. m., as Ca CO,, about 2,500 lb. of 100 per cent. H2SO4 per mil. gal. would be required to exactly neutralize the sewage. On a practical scale, an excess of the theoretical dose would be required to insure acidity at all times, probably 3,00(3 lbs. per mil. gal. Eogers and Aubert (treatise on Industrial Chemistry) give the cost of manufacture of tower aciid (about 78 per cent, strength) by burning pyrites as $6.50 per ton, equivalent to about $8.35 per ton of 100 per cent. acid. On this basis, treatment at the rate of 3,000 lb. per mil. gal. is equivalent to about $12.50 per mil. gal. for acid alone. Omission of the concentra- tion process, or use of the sulphur dioxide resulting from the burning of sulphur or pyrites directly may influence the cost. The complicated apparatus necessary for operation and possi- bility of corrosion by the acid on materials ordinarily used in con- struction need consideration. Equipment is also required to recover the fat precipitated with the sludge. In the past this recovery has seldom proved remunerative, except on wastes containing more fat than is here present and except where the cost of sludge disposal is a factor. CONCLUSIONS. The results on hand indicate that treatment of this sewage with acid results in a somewhat greater retention of fat. An apparent reduction in the oxygen demand over that result- ing from plain sedimentation, while remarkable, is probably not real, being simply due to a retardation of decomposition by the sterilization of the bacteria present, the organic matter being left in solution. If thoroughly seeded with new bacteria, decomposition will again continue with renewed bacterial action. However, therfe appears the added cost of acid treatment and the cost of recovery of the grease, as well as the uncertainty of the price, to be received for the grease recovered. 195 CHAPTER XV. OXYGEN REQUIREMENTS. GENEEAL. For ease in comparison, the oxygen requirements are collected here under one head. The method of investigation is one recently developed by Dr. Arthur Lederer, described- in detail in the May, 1914, issue of the Journal of Infectious Diseases. METHOD OF PROCEDURE. The method is based on the addi- tion in excess of definite quantities of saltpeter (sodium nitrate) and methylene blue to the samples of the sewage or effluent to be tested, followed by inctfbation for 10 days at 20 deg. C. The residual total oxygen is then determined. The saltpeter added is a standard solution of known strength. Extended observations have indicated that 2 molecules of the salt yield approximately 5 atoms of oxygen available for oxidation of putrescible organic matter in sewage liquid. The oxygen consumption is the difference betw_e.en the reside ual oxygen after 10 days' incubation and the amount originally added. The period of 10 days was selected because experience has mdicated that samples which hold out for that period may, for all practical purposes, be considered stable. The initial available oxy- gen ia the crude sewage and tank efSuents is frequently low enough to be of no practical importance, but in the sprinkling filter effluent it is a large proportion of the total oxygen demand, ofter exceeding TABLE 110. COMPARATIVE OXYGEN DEMAND AND SUSPENDED MATTER FOR CRUDE SEWAGES AT CENTER AVE. AND 39th ST. Pakts per Million Period 1914 Biologic Oxygen Consump- tion Suspended Matter Center Ave j 39th St. Center Ave. | 39th St. Jan. 14 to 31 990 130 120 100 120 130 140 467 453 478 424 444 433 138 Feb. 17 to Mar. 3 Apr. 15 to 30 . . 1030 .. 880 75 70 May June July .. 930 . . 1010 . . 1080 130 195 140 Weighted Average .. 990 130 444 135 196 it. The methylene blue serves as an indicator, the color disappearing ■when an insufficient amount of the saltpeter is used. Up to May 1, 1914, two samples of crude sewage and of the effluents from each device were taken daily, the sewage samples being collected at 9 A. M. and noon or 1 :15 P. M. and the effluents with proper allowance for the nominal detention period. Subse- quently, samples were collected every two hours throughout the day (8 in all) and incubated. At the end of 10 days, the samples were mixed and the residual oxygen determined for the composite samples. In this way, much more representative results were ob- tained. Determinations were made on Monday, Wednesday and Fri- day every other week and on Tuesday and Thursday of the alternate weeks. CRUDE SEWAGE. The oxygen requirements of the crude TABLE 111. COMPARATIVE REDUCTION IN OXYGEN DEMAND AND SUSPENDED MATTER FOR VARIOUS SETTLING TANKS. Period 1914 No. Days BlOLodiC OXYGBN CONSUMP- TION — ^PaETS per MlIiLION Pee Cent Rbduotion Re- marks Grit Cham- ber Dort- mund Tank Em- scher Tank Chem. Precip. Dort- mund Tank Em- scher Tank Chem. Precip. Jan. 14 to 31 Feb. 17 to Mar. 3. . . . Apr. 15 to 30 May June July 5 5 5 10 10 10 990 1030 880 930 1010 1080 850 640* 670 650 640 880 760 630* 630 540 560 750* 610* 560 700* 570* 18 22* 28 35 41 11 26 24* 33 47 48 22* 36* 40 33* 48* *4 days *4days *7dayB *8days Weighted Av. 990 680 630 620 32 36 38 Suspended Matter Parts pee Million Pee Cent Reduction Jan. 14 to 31 5 467 210 55 Feb. 17 to Mar. 3.... 5 453 178 170 111* 61 63 74* *4days Apr. 15 to 30 5 478 157* 165* 138* 68* 67* 72* *4 days ^ ay 10 424 162 153 81 62 64 81 , . June 10 444 122 112 134*. 73 75 70* *7days July 10 433 150 130 141* 65 70 69* *8days Weighted Av. 444 150 148 118 66 67 74 Note. Samples of grit chamber effluent omitted on days when no tank sample was collected in figuring per cent reductions. 197 day sewage and the total suspended matter are given in table 110, with similar figures for the 39th St. sewage. Measured by the relative oxygen demands, the heavy day sew- age received at the Center Ave. testing station averages about 8 times as strong as the domestic sewage received at 39th St. EEDUCTION IN OXYGEN REQUIREMENTS BY SEDIMEN- TATION. The improvement in the oxygen consumption by sedi- mentation in various devices is summarized by months in table 111. Conditions of operation for the various tanks have been given in previous chapters. Comparison with the reduction iu suspended matter shows that the reduction in oxygen demand is fat below the reduction in suspended matter. An average decrease of 32 per cent, was indicated for the Dortmund tank, 36 per cent, for the Emscher tank, and 38 per cent, for the chemical precipitation tank. The cor- responding reductions in suspended matter were 66, 67, and 74 per cent, respectively. Recent results were in general better than dur- TABLE 112. REDUCTION IN SUSPENDED MATTER AND BIOLOGIC OXYGEN CONSUMP- TION BY ROTARY SCREEN ON CENTER AVE. SEWAGE. July 8 to 30, 1914. Date 1914 July Suspended Matter Pabts per Million Crude Screen Effluent Det Screen. Lbs. per Mil. Gals. Biologic Oxygen Consumption Parts Per Mil. Crude Screen Effluent Pee Cent Reduction Susp. Matter Bio. Ox. Cons. 8 489 434 454 1210 1100 11 9 10 330 301 238 900 890 9 1 14 400 375 210 1020 1050 6 3* 16 439 398 342 1180 1060 9 10 20 389 366 194 1060 1020 6 4 24 505 470 289 1120 1010 7 10 28 523 473 420 1180 1050 9 11 30 821 775 382 1090 1040 6 5 Average 487 449 316 1100 1030 8 6 * Denotes increase. Note. Suspended matter in crude sewage is calculated from determination 'on effluent by addition of weight of dry screenings. Per cent reduction is based on this also. 198 ing the winter, perhaps because the method of sampling was more representative after May 1st. Although the operating conditions of the different devices were changed several times, these experi- ments indicate that on the Center Ave. sewage efficient sedimenta- tion, will reduce the oxygen demand from 25 to 45 per cent., with a reduction in suspended matter approaching 70 .per cent. EBDUCTION IN OXYGEN REQUIREMENTS BY FINE SCREENING. To determine the effect of fine screening on the oxygen demand of the crude sewage at Center Ave., routine tests were made during July, 1914, on the effluent from the rotary screen. The results of these tests, with corresponding determinations of suspended matter (table 112) show the improvement in oxygen- re- quirements by fine screening to be small, averaging about 6 per cent, for the 8 tests made. The reduction in suspended matter averaged 8 per eei;t. for the entire series, based on computed influent analyses. Use of actual suspended^matter determinations on the influent showed an aVef age reduction of only. 3 per cent. This lattei' figure is low, and probably in error because of the difficulties in sampling. REDUCTION IN OXYGEN REQUIREMENTS BY FILTRA-^ TION. Table 113 shows the results obtained by months on the sprinkling filter, fed by the Emseher tank. Up to April 1, 1914, the filter -was operated-at a net rate of yield of |, mil. gal. per. acre daily, and thereafter to give a net yield of one mil. gal. For comparison, the grit chamber and Emseher tank figures are included! The reduction in oxygen demand is very marked, averaging over 90 per cent, of the amount required by the crude sewage. Of this from 25 to 45 per cent, may be produced by the tank treatment. Although the total gross reduction in oxygen demand is large, the net demand or amount of oxygen which must be supplied from ex- ternal sources is reduced even further, because the effluent contains a large part or all of the oxygen required for stability in the form of free oxygen, nitrites, and nitrates, all readily available. During May, June and July, 1914, the available oxygen in the filter effluent was more than sufficient for stability, or in other words, the relative stability was over 100. Treatment of the Center Ave. sewage on coarse grained or sprinkling filters up to rates of yield of one mil. gal. per acre daily, when preceded by thorough preliminary sedi- mentation is apparently capable of producing an improved effluent usually containing sufficient available oxygen to require little dilu- ■tion for complete stability, and for days at a time containing an excess, being then completely stable. 199 s !>. 1 1 ,, > += 11 PhM i-H gt^ooo o 3 ■^ to ■^ O 1-H 00 o M^ OSOOO o o t^ I>- CD I> !> CD t* rH T-H rH t^ lO (M J:) C5 tSn o B iOtJho'cD.CO^ cm 3 g 5 11 o 0^ o 3 CO p W « >. s S O P^ 00 ■* OIXN M =2 a Oi(N O-^-^C 7i 00 K M 03 an t^ t* t^ CO lOlO to . an iOcDl><:ol>t O CO P4 f§ H w 1? M IC lO (M (© (N 00 o <1 t-iO ^(N g • > p^ d ^ "3 Q § S -4^ ■^ t^ CO -^d^ lo o ■* aiS ^ Omt~ooto fe O hi F^ M M mi (m' lO ■*' CO CO lO 1-H C<' I ^ O ui t^ t^ CO CO lO »o CD H 1—1 Iz; & 5 ^ HH o, }z; o tiH s„< O H •a o -1 o oooooo ^H CO COCOtNt^ OOOOOJOO g mPh 00 CO (M -<*< 00 l> ^p '^^ '^' ^^ ^^ ^ OS CO R H P^ >- "^ W ^1-3. a < ^°«l NlO-^OOSffi T— 1 (Mit3-*ocno- T— 1 i a 1 >< .CO ; ■ CO ; to A4 O Is 1 CO^M 1 s o g o 5-25 3 °5 1 o fS-" :^^2 1 * 1 1 1-5 > 1-5 1 iiil 1^ i: 1 200 CHAPTER XVI. EXISTING SEWERS. CITY AND PEIVATE SEWERS. The municipal sewers re- ceiving waste from Packingtown and the Stockyards include those on Ashland and Center Ave., 39th St. conduit and two sewers on Halsted St. (table 114), which discharge into the east and west arms of the South branch (fig. 18). In addition there are a number of private outlets (table 115) as follows: Sulzberger Sons Co., Hipe Bros., Swift & Co., Friedman Mfg. Co., Anglo-American Packing Co., Western Packing & Provision Co., Union Stockyards and Tran- sit Co. (Morgan St.), and the Chicago reduction plant. Private sew- ers also enter from the Eagle Brewing Co., Hately Bros., Cold Stor- age, and from the Union Stockyards and Transit Co. filter plant. Robey St. sewer discharges into the west arm, but is practically wholly domestic in character. The 39th St. conduit receives the waste of the Brennan Packing Company. Several small houses on 39th place drain into the 39th St. sewer. ANALYSES. Analyses have been made at intervals of various . samples from the sewers on Ashland Ave., Center Ave., and Morgan St., as well as most of the other outlets mentioned. The results (table 116) show a very strong sewage, as a whole, particularly in Ashland and Center Ave., not only high in suspended matter, but also in oxygen consumed, indicating a sewage about 5 to 10 times as strong as the average normal sewage found at 39th St. jtesting station (table 116), and very much stronger than the sewage from Robey St. The analyses of the sewage at 39th St. pumping station repre- sent nearly an average domestic sewage, south of the Chicago river, with the exception of the loop district, which is slightly stronger. The analyses of the Halsted St. sewers were of samples col- lected over a very short period.. The south sewer appears weaker than the north. At other times, however, the sewage has appeared unusually strong, containing blood and other evidence of packing- house wastes. The great variations in strength of the Center Ave. sewage at different hours of the day are shown by the results of a week's run in the fall of 1914 (fig. 19). Two-hour composite samples made up of equal portions collected, every 15 min. were analyzed for sus- pended matter. Although slight rains occurred on Oct. 26 and 28, 4-7'^S/. Fig. 18. Stockyards and Packingtown Region. Sewers tributary to East and West Arms of South Pork of South Branch of Chicago River. Note. — Red tint indicates area devoted to packing and allied industries. One alternative of proposed intercepting sewer is shown in red. 201 iij 'Si ^ 11 o ni a -a ^£ •^ ^ t4 ^■Si (^ ^ !« ll _>; (3^ a; ^ 5 M 5 iii ° s « g"S g oil a> a « « o Pi Pi fi 0) T-H ^ ^ 5 ■§"§13 &0 c3 03 d c3 o s S o Q ■ o o f=i g § g 1-1 Is- to (N Iffl ■* 1> tJH lO O OS jj ^ ,S CQ OQ OS'S WW > >: < ■< TJ u •a 3 u <1 03 5? .a Q g- 202 TABLE 115. DATA ON PRIVATE SEWERS ENTERING EAST AND WEST ARMS OF SOUTH PORK OF SOUTH BRANCH OF CHICAGO RIVER. Description Size Diam. in Inches Bank of River Actual Flows Cu. Ft. per Sec. Remarks Average Daily Max. Observed Morgan St 20 12 'So. No. So. No. So. So. So. So. So. 1.9t 0.88* 1.8 0.2t 0.2t 0.12 0.76 0.2t 0.5t 2.4t 1.18 2.61 0.5t 0.61 0.17 0.91 0.5t l.OOt Union Stockyards & Western Packing TDo . . Anglo American. ..... White Eagle Transit Co. Packinghouse waste, 4 outlets. Packinghouse (1911). Brewery. Chicago Reduction Co. Friedman Mfg. Co Swift & Co Plant recently rebuilt. Butterine makers. Miscellaneous Connec- Hine Bros. Co Sulzberger Sons Co. . . tions. Reduction and render- ing. Drainage from bacl^ of yards. * Average of 9 hour observation on two outlets, t Day hours. [ t Estimated. the test represents essentially dry weather conditions. For com- parative purposes, composite discharge figures from fig. 20 have been added. CONDITIONS NOT NEW. As far back as 1890, the analyses made by Prof. J. H. Long of the discharge of various sewers, in- cluding Ashland Ave., show a very strong sewage (tables 1 and 116). Altho his sampling extended over one month, the results agree very closely with those obtained by the Sanitary District in 1911 and 1913 (table 116). GAGINGS. From time to time gagings have been made of the fiow of the various outlets. The outlets of the two Halsted St. sew- ers were so inaccessible that no gagings were made. The 39th St. conduit receives domestic sewage and flushing water, as well as the discharge of the Brennan Packing Company. No samples were taken other than at the Brennan plant (appendix 7). All the indus- trial sewers have a very marked difference between day and night fiow, the day flow being much larger, in distinction to the more uniform flow found in the purely domestic sewers (fig. 20). SPECIAL GAGINGS. Special gagings were made on Center and Ashland Aves., and Robey St. in 1911, about the time of the ex- tended gagings in Packingtown (chapter 2). A weir was built in the outfall of the Center Ave. sewer below 20c ui o J o CO H < I- o -, ^ r .a B-. CO-^OM tH T-( -^ CO O CO .... la^to CO ^ N 00-*O^ Ot>J> ooooo M rH CO - IVCOCO IO(MCO |z; OO '^'^ 0 "cH COOO • 00 Q cq as 05 O 00 S^S! • Ttioo 1—1 OOt^rt ^■h a OJ ooo (N CO ■ t-H a •" bo COOIO c? ■ 1 s|fe 1—1 1—1 rH lb OCO «^:HIN COtH^ oi^Q (N 1-1 O 00-' ■* I. N ■ OOi-t t^ K ti ■ o • ■ ^ 1*0-* Sec (M . h n C9 ■s 1-1 o I— I OCO(M COOOOOl 02 1 coic cq tvOO 00 -, d^ -1 ■*^ P, -la n H Tl ^ -y a i aco 3 ■ 9 fci S* a a &, i-Ti-T 1:3 ■^■^ 1—1 1— ( C»05 1—1 rH ^ ^^ 00 o> .& T3T3 (MIM .»^ ^*^ >-. >= § fnfo ;?^ kSS 204 N joaooag ^at/^sq^ . o/i^n^ - s'Sjot^as/ff' § S § ^ ^ ^ § > 1 % Q L " 1 t - r }} > 1 1 1, si^ ^ ■^ « b ^ ^. r' j ^ 1 1 — — "■ - __ — l:s 1 ^ k 1 1 1 ! > ) ^ ^ -i i:'" '^^ ^i ' — — /■ J 1 i^ 4-- f" t^ ! ^ \.^ t f ^ lii I 1 1 > xi 1 1 h I^ t^ V ^ ■^ ^ :=^ l / I 1 1 *^ r ""— ttj< — ! = T 4 i. 1 fi 1 1 1 . 1 1 } > ^ 1 § ^ !<; ^ 1 y _r ^ ^ ^ i ' 'iZ^ 1 \ 1 1 — '■ _i- -~— . "~~^ _ <1_ 1=L»- 1 1 1 1 J 1 > . ^ -^:^ ^ *! 1 ■ ^ J S \ 1 ^ 1 - ■=^ = [ ^i.^ Ti — V > ^ 1 1 / 1 r ► ^ 1 •^ ^ <>i ^ /■ __. •'' 1 ^ — — — ■ ^-- 1 =^ I I I I § I ao////iy -/3c/s^.je>c^-^i>^/P^ fiapt/ac/snff \ Oi ^ >> CD > m < -M t. S U J3 c O 1 C OJ ig Pi £. (1) 0) a 5 crt IS BJ S b o 71 ■D 1^ u a a m 3 (0 ^ •s M r o •in •M Q n ^ > P >i tin 3 m h Z ^ i o> fl> □1 ^ U.|Zi 205 puoosgjgj ^aaj o/c^nj.aBjoL/osig puooag ^9c/^s9j oiijn^ - sb-ioL/osia 206 TABLE 117. TEST OF CENTER AVE. SEWEB. May 16 to 18, 1911. May- Period Suspended Flow Matter Cu. Ft. per Sec. P. P. M. 23.1 621 17.0 161 25.3 649 16.8 149 28.8 759 16 Noon to 8 p. m 16 8 p. m. to 17, 8 a. m. 17 8 a. m. to 8 p. m. . . . 17 8 p. m. to 18, 8 a. m. 18 8 a. m. to noon Average for period 48 hours 21 . 1 402 the outlet of the Armour grease skimming basin, the gagings being given in table 117. The maximum flow was 30 cu. ft. per sec. over 2 hr., the minimum flow being 16 cu. ft. per sec. for 1 hr. At the time the testing station was placed in operation, a new weir was built at the sewer outlet and hourly readings were taken for about one year. The results are summarized by months on table 118. The average flow during this period between the hours of 8 A, M. and 10 P. M. was 29.0 eu. ft. per sec. and the average between 11 P. M. and 7 A. M., inclusive, was 16.4 cu. ft. per sec. The maximum dis- charge recorded was about 105 eu. ft. per sec. on May 20, 1913. A weir was built in 1911 on the face of the outfall at Ashland Ave., the gagings being given in table 119. The maximum flow was 31.5 cu. ft. per sec. for 1 hr., and the minimum flow 18 eu. ft. per sec. for 3 hr. A few measurements, made in the fall of 1913, showed an average dry weather discharge of about 35 cu. ft. per sec. between 8 A. M. and 10 P. M., while the night flow dropped to from 25 to 30 cu. ft. per sec. A discharge of 80 cu. ft. per see. was observed on Sept. 16,'l913. A weir was built in' the outfall of the Eobey St. sewer, about 15 ft. south of the river bank, the gagings being given in ta)i)le 120. The maximum flow was 11.7 cu. ft. per sec. for 1 hour and the mini- mum flow 9.4 en. ft. per sec. during 2 hours. On Aug. 12, 1911, one reading of 37.2 eu. ft. per sec. was obtained, imnlediately after a heavy rain. Since then the weir has been carried away twice by storms, but each time has been rebuilt. Continuous records with a Bristol recording water level gage have been kept since Sept. 4, 1912. Table 121 shows the results for 1913, averaging 13.2 cu. ft. per sec. with a maximum flow of 135 cu. ft. per sec. PACKINGTOWN SEWERS. The sum of the discharge of the various individual plants examined during the period of four months 207 I s iz; O H p3 O bJ o « IS h Eh tf "Slew ^ o 4 M CO hH W' a a^ QO^M a p, p 00 '^M • >5 ■ c3 ■-0 •T3 • to OOt^OOCOOOOOOOr-l ■^COCX)i-HMCO>OCD001> Mt>I>T)HO0000l^-*O OOOi-HCOlOCDlOi-H-^O OOtHOCDQOOOIOOOOOO QOCOC^Ot^OCOCOOOO 0-* C0-^i-Ht^l>|>.00OC 62.6 40.7 36.6 135.0 53.3 88.0 81.5 49.3 26.9 40.7 13.8 ,15 days only. March April 23 days only. May June July August September October November December Average or maximum . . . ... 13.2 82.6 135.0 TABLE 122. COMPARISON ON FLOWS IN PACKINGTOWN AND IN SEWERS ON ASHLAND AND CENTER AVES., 1911. Description Flow in Ctj. Ft. per Sec. Day a.m. to 8 p.m. Night 8 p.m. to 8 a.m. Center Ave. Sewer 25.7 Ashland Ave. Sewer 28 . 3 Center Ave. plus Ashland Ave 54.0 Paokingtown computed total 31 .7 16.9 18.5 35.4 12.2 211 +3 ingoooooooo t>|Ooo>gooooo oooocnooooo • oooodo- o : In 1 oooooooooco gogoo^J^^oom oooooooooooo O O OO O O O 1-H o 03 CO 13 >-> gOOOOOOOOO OOOlfflOOOSOOO ooooooooooooo <=> o ^' do 05 T- q°°!§MOc5°°° gOOj^OOOOgO OMOO^ggOOO ; .d dddd d d d d i-idd • co CD CO & § OOOC0O«g5OOO CQiOOOOOOOOO OOOOOOOOOCOO d dd^ dd ^ o c<: R -i-*'i-l t-iOOOO ■ • ■ 1— JO O O OOt— 1 •■• OO d d oo<5 '■ : '■ d d 4 ^OgOOOOOOO O OO O t^O OO 00 (N O ^ O ICO OOO O CM O CO d do d dd d d d r-i o CO T— 1 OS 1-H 6 Q ^fnfnOOOgOOO OOOOOOOOOf-t OOt-n OOOOOOOO d d . dd o d > 1 OOOOOOOgOO OOO^OOOOOO OOOOOOOOIM 0(N05 ; S3 d <5 '-t OO O COOCD Oi T-H O T-H o O O O OO OO 1-H OO OO O O t^ t^ O cDi-H T-H (MOOO -TtH lO C> M (NOt-hO Oi (N J OOOOOOOmOO OOOOOINM Ph O m T-HOO OOOt-hOCDt-h • p wsin^T-Hp pT-Hp; 1 MOOOOOOt^OM 3JOgMOOOOOO O.OT O O O O O O O O t-h 0000s0000-*0 OO O (M O *0 O (M O CD O O t^ O O O O O O O tH p t>. pt-hc^jpp p p \ T-H T-H CD CO CO 1 OOOOOOOOOO OOOOOf-lOOOO ig^OOJOOOOOO ■ d >» OOOOOOOOOfH OO-a "-lOOOOOOO (N OOOIN OOfHOOfH E5 1 OOOCOOOOO0 T-H O O T-H O O O O OOOOOOOOOO • T-H T-H CO (N (N p ^ ; I— 1 1 ^Nco^ifflcot-oooo ^HNM^usco^SSg nnS^cJSnc^SSm H 212 CHAPTER XVII. PROJECTS. OBJECT. The purpose of the investigation has been two-fold, first, to learn how to relieve the load upon the Main Channel com- ing from the organic wastes of this industry, and, second, how to remove the local nuisance from Bubbly Creek. Various projects have been considered, including the filling of Bubbly Creek, but all re- quire the treatment of the industrial wastes and a certain amount of sewerage construction and revision to collect the sewage from industrial plants for treatment. SUGGESTED IMPROVEMENT. The controversy now pending with reference to limitation of the diversion of water to be with- drawn from Lake Michigan by The Sanitary District of Chicago has made it difficult to determine the final solution of the problem considered in this report. However, The Sanitary District has taken the position that the question of disposal of the industrial wastes is distinct and separate from that of disposing of human sewage, and that in accordance with the organic law the indiistrial wastes must be treated, irrespective of the outcome of the controversy. Ultimately the complete treatment of the industrial wastes seems necessary, in order to relieve the great oxygen demand of such wastes. On the other hand, the first step is to remove the settling suspended matter, by screening and sedimentation. This is essen- tial in any case, and is needed at once. Whatever sewerage con- struction is planned in connection with the removal of the settling suspended matter and otherwise must be flexible enough to fit every contingency. The diversion from the proposed Center Ave. sewer of the indus- trial wastes from Packingtown and the Stockyards seems desirable to give the municipal authorities the greatest flexibility in meeting future conditions. "Whatever be the diversion of water allowed from Lake Michigan, this plan lends itself readily to future development. It reduces the amount of domestic sewage to be mixed with the indus- trial wastes, relieves over-burdened sewers, and concentrates the waste of an industry for the most efficient handling. POLICY. At present, the only course open to the Sanitary Dis- trict is to continue the dilution of domestic' sewage, and as far as possible to secure the treatment of industrial wastes, in order to comply with the intent of the organic law. The handling of the in- 213 dustrial wastes is immediately contemplated, and the suggestions of the steps to be undertaken are embodied in this chapter in ac- cordance with the investigations outlined herein. Who shall bear the burden of cost is yet to be determined and adjusted. In the, ultimate treatment of the industrial wastes from the Stockyards and Packingtown, biological works seem necessary Space is lacking for such works in the immediate vicinity of the Stockyards, and would need to be sought elsewhere, undoubtedly to the westward. The problem involves many ramifications both legal and otherwise, that have not been considered in detail in this re- port. It would involve the construction of a long intercepting sewer along city streets and private right of way, the acquirement of large areas of land, and the construction and operation of a pumping station, sprinkling filters and collateral works. RECOVERIES. From the standpoint of recoveries, each indi- vidual house or firm should endeavor to retain or use all material of value before the sewage reaches the sewer outlet of the house or firm. Many already do so, but some of the smaller houses do not. If not already installed, this means the use of reduction tanks, the saving of tankage, the: evaporation of tank water, and constant care in avoidmg careless handling of waste, particularly paunch manure. Adequate grease skimming basins should be installed. Before the sewage passes to the municipal sewer, fine ■ screening is desirable, followed by sedimentation. Co-operation among the houses would materially help, as some have greater facilities than others for use of recoveries in by-products. TREATMENT. Prom the standpoint of treatment of the Cen- ter Ave. sewage and Packingtown waste, several steps or degrees of efficiency are open: — 1. Pine screening. 2. Pine screening in combination with sedimentation. 3. Pine screening, in combination with sedimentation, followed by biological treatment on sprinkling filters, and second- ary sedimentation. While our screening tests indicate a greater removal at the individual plant or outlet than at the community outlet, the im- provement thereby alone does not appear sufficient. It is important that all the settling suspended matter be removed. Por this, sedi- mentation appears needful. Screening is helpful in removing light organic matter, relatively slow to decompose, which binds the sludge together and by rising tends to produce large amounts of floating scum. The problem of the Stockyards is slightly different from Pack- 214 ingtown, in that the sewage discharged contains principally hay, mud, manure, and urine. From the Stockyards the sewage can read- ily be collected as a whole and kept distinct from Paekingtown in the preliminary treatment. Screening and sedimentation appear needful at present. When the installation of biological treatment is made, as in the case of Paekingtown, the same general circum- stances would govern. Screening and sedimentation plants, whether individual or col- lective, should be designed so that the effluent can be readily diverted and connected with biological works. Biological treatment in general requires far more space than is available at the Yards or Paekingtown. Consequently, a plant would be located at some distance, perhaps outside the western limits of the city, to the south of the Main Channel. A long inter- cepting sewer would be needed, in the operation of which prelimi- nary screening and settling would be advantageous, in avoiding deposits from a sewage so heavily laden with settling suspended matter. ASSUMPTIONS. In all the projects considered, the pumpage from 39th St. has been assumed to enter the East Arm, as hereto- fore. The other municipal and private sewers from Halsted St. west to Robey St. are included in the various projects as therein outlined. A description of the various sewers is given in Chapter XVI. In studying the situation from the standpoint of treatment of industrial waste, the assumption has been made that the present load will not materially increase in the near future. Inspection of the kill in Paekingtown (fig. 1) shows practically no increase since 1902. With the growth of other packing centers, the improvements in the industry, and the increasing attention given to details through Federal and State supervision, this does not seem unreasonable. FILLING BUBBLY CREEK. From the sanitary standpoint the fiUing-up of Bubbly Creek (i. e., the West Arm of the South Fork of the South Branch of the Chicago River) would be desirable, altho mere filling alone would simply transfer the nuisance from one locality to another. With suitable treatment of the industrial wastes, it is entirely proper that this dead arm be filled and that the ground area be used as a site for sedimentation tanks. If the City of Chicago requires facilities for water transporta- tion at its reduction plant, the fill can commence just west and south of that property, continuing past Ashland Ave. to the west end of the West Arm. If the city will abandon water access, the fill can be extended to the Forks. For years the West Arm has served as a crude settling basin 215 retaining settling material. To fill it up without provision for set- tling suspended matter, would transfer the sludge to other locali- ties, and cure one nuisance to create another elsewhere. Hence any scheme involving the filling of the West Arm should include certain requirements to protect the Main Channel and appurtenances of The Sanitary District of Chicago. The points to be kept in mind are as follows : 1. The flow in the West 39th St. conduit should be increased. This may be done by the introduction of the Robey St. sewer and sewage from the east thereof, including Stock- yards and Packingtown. 2. The sewage from the Stockyards and Packingtown should be treated as herein outlined. 3. A portion of the bed of the West Arm should be reserved for a sedimentation plant for the Stockyards and Pack- ingtown project. 4. Incidentally (in connection with 2), the sewers of Packing- town and the Stockyards should be remodelled to keep industrial sewage out of the proposed Center Ave. sewer. The areas to be recovered between the points stated are as fol- lows: A. End of West Arm to Ashland Ave. 11.5 acres. B. End of West Arm to W. 39th St. 16.5 acres. C. End of West Arm to Forks 24.3 acres. The amount of fill required up to elevation +8.0, C. C. D., for the entire West Arm, west of the Porks is 900,000 cubic yards. Tlje amount of fill required up to elevation +8.0, C. C. D., for the West Arm west of the City reduction plant is 600,000 cubic yards. If 6 acres be left open for the sedimentation plant, the fill re- quired up to elevation +8.0, C. C. D., west of the reduction works is reduced to 400,000 cubic yards. The material for filling will be available in part from the con- struction of the new Center Ave. sewer, from the excavation for the intercepting sewer proposed herein and from the excavation for the sedimentation tanks. The balance can be furnished by dumping ashes and excavation from other sources. Should the owners of the abutting property desire, bridges at grade can be built across the West Arm at sufficient intervals to provide means for shifting freight, etc. AREAS TO BE RESERVED. For treatment by sedimentation of all the sewage collected from Halsted St. to Robey St., inclusive, about 8 acres would be required for tanks and 7.5 acres for sludge 216 beds, on a basis of population estimated for 1922, making a total of 15.5 acres out of 16.5 acres available, if the Creek is filled to W. 39tli St. For extensions, eventually the entire area reclaimed would appear inadequate. For treatment by sedimentation of the Stockyards and Pack- ingtown vi^astes alone, with a small ^ amount of domestic sewage, about 6 acres are required at present for tanks and sludge drying beds. Greater area might be required later, possibly not over 3 acres additional. PROPOSED SEWER TO REPLACE EXISTING CENTER AVE. SEWER. Mr. C. D. Hill, the Engineer of the Board of Local Improvements, has under consideration a sewer on the general line of Center Ave. which will materially change sewerage conditions in Packingtown. This will discharge about 100 feet west of the Center Ave. bridge, with an outlet 11 feet in diameter, and an invert at elev. — 4.0 C. C. D. The grade will be 0.03 per cent. His plan in- cludes intercepting the existing Center Ave. sewer south of 47th St., as well as the present sewers on Ashland Ave., Halsted St. and Wallace St., south of 52nd St.; and the- branch of the Robey St. sewer on Ashland Ave. south of 68th St. About 1 square mile south of 87th St. is also to be made tributary. The total drainage area will be about 4,500 acres, on which reside at present a population esti- mated at about 150,000. The construction of this sewer will reduce the flow in the present Center Ave. sewer to that coming from the Stockyards proper and a few packing houses. The flow in the other sewers affected will also be reduced. Unless the sewers in Packing- town are remodelled, about one-half of the wastes would enter the new sewer, as it would cut all the sewers now entering the existing Center Ave. sewer from 47th St. north. Our estimates are based on the conditions which will exist when the proposed sewer is com' pleted, and the portions of flow diverted to it which now enter the Ashland Ave., Halsted St., Wallace St. and Robey St. sewers, as above stated. SEWERS REQUIRED. The sewerage requirements hinge large- ly on the policy of treatment adopted. Out of four alternatives described herein there are at least two clear cut projects which appear entirely feasible. I. Project I assumes that all the wastes are treated by screen- ing and sedimentation at the points of origin. A sewer is required across the present creek from Robey St. to the entrance of the pres- ent W. 39th St. conduit, and an interceptor from the new Center Ave. sewer west to the W. 39th St. conduit. The West Arm can then be filled up. As the treatment of the industrial waste at the 217 point of origin to the degree required may be difficult on account of lack of space, this project does not appear wholly desirable. II. Project II assumes that all the wastes are treated by screen- ing at the point of origin and collected by an intercepting sewer to a community plant in Bubbly Creek for settling. A sewer is required from Robey St. to the entrance of the present W. 39th St. conduit, with an interceptor running along the south side of the Bast and West arms from Halsted St. to the sedimentation plant, the effluent of which would discharge into the West 39th St. conduit. Project II is based on keeping the industrial wastes out of the proposed Center Ave. sewer and diverting them into the Ashland Ave. by building certain trunk lines east and west in Packingtown. This project appears decidedly feasible. III. Project III. assumes the undertaking of treating both in- dustrial and domestic sewages at the present time. It then becomes possible to collect all the sewage from Halsted St. west to Robey St. into a common plant for settling, assuming the screening done at the point' of origin. This, however, would require a very large area. The space available in Bubbly Creek west of W. 39th St. would not be adequate after 1920 or thereabouts. Moreover, this does not shape readily to future extension, particularly if the diver- sion allowed by the government is low. IV. Project IV assumes that all industrial wastes are treated at the point of origin by individual screening and settling plants. A sewer would be built across Bubbly Creek from Robey St. to the en- trance of the West 39th St. conduit, and the Ashland Ave. sewer would be diverted to the east. The West Arm could then be filled up. This, however, does not appear feasible, not only for the reason given under I, but also because the W. 89th St.- conduit would sludge up and be productive of nuisance, the combined low flow of Robey St. and Western Ave. sewers being entirely inadequate to maintain scouring velocities. Prom the standpoint of ease of extension, protection of W. 39th St. conduit, and future provision for further treatment to the west- ward, project II appears decidedly desirable and worthy of close study. Project III is less meritorious, including necessarily treat- ment of more domestic sewage and being less flexible both at pres- ent and in the future. PACKINGTOWN SEWERS. In general, the impression is cur- rent among representatives of the packing houses that the existing patch-work sewer system in Packingtown is largely inadequate for present needs and unable to cope with heavy rains without flooding. As there are comparatively few cellars, this is not so troublesome as 218 might otherwise be. The houses draining into the Center Ave. sewer, particularly the Hammond plant, are seriously bothered, as the Center Ave. sewer is too small to handle heavy rainfalls. "WhUe oijr estimates for remodelling Packingtown sewers include an amount, stated in each ease, for new sewers, these are merely trunk sewers. The estimates do not include any cost for rebuilding indi- vidual systems or for new connections to the proposed sewers. For an adequate estimate on the cost of that work a very detailed rmder- ground survey would be required, and considerable planning and study to figure out ways and means to tap and remodel a network of sewer pipes, many unknown, preserve sewerage facilities and re- build on streets, constantly in use and frequently too narrow for ordinary trafSc. ESTIMATES. The estimates given herein are preliminary esti- mates, with due regard to local conditions, but are not based on any extended surveys or actual designs. They are approximate, pre- pared primarily to indicate the expenditures required to meet dif- ferent alternatives of sewerage and treatment. In no case is any allowance made for legal, engineering, land or right of way ex- pense. Provision is made in the estimates for treatment only for a flow based on present conditions, assuming however that the Center Ave. sewer is built and the adjacent sewers relieved. No allowance is made for capacity to care for any growth in the immediate future, for reasons already stated. SEWERAGE PROJECTS. Four sewerage projects are sug- gested, in addition to the remodelling of the sewers in the Yards and Packingtown. In these, unless otherwise stated, the proposed Center Ave. sewer is assumed to be built with the changes previously noted, which will reduce the dry weather flow in most of the contributory sewers. A. The Robey St. sewer can be connected to the entrance of the West 39th St. conduit by a 9 ft. circular sewer, about 800 ft. long, of which at least 150 feet would be carried on piles. This would cost about $35,000. The Ashland Ave. sewer can be extended easterly about 2,600 feet to the East Arm at or near the Forks. This would be a 6 ft. circular sewer, costing about $40,000. The fault of this project is that sufficient dry flow would not be assured to maintain scouring velocities in the West 39th St. con- duit. B. A gravity interceptor can be constructed from Halsted St. west to the inlet of the West 39th St. conduit. All the sewers dis- 219 .charging into Bubbly Creek would be tapped, with the exception of the proposed Center Ave. sewer. The dry flow and a portion of the storm flow could be handled. This requires about 2,190 lin. ft. of 5i ft. circular sewer, 3,560 lin. ft. of 6 ft. circular sewer, 2,580 lin. ft. of 7^ ft. circular sewer, 800 lin. ft. of 8 ft. circular sewer, with a crossing of the West Arm, a siphon under the proposed Center Ave. sewer and other appurtenances, at a total cost around $150,- 000. C. A gravity interceptor can be constructed from Halsted St. west to the inlet of the West 39th St. conduit, at an elevation low enough to tap the proposed Center Ave. sewer. An overflow weir can be provided at Center Ave. to care for excess storm flow. The sewer would follow around the south bank of Bubbly Creek, requir- ing about 2,190 lin. ft. of 5^ ft. circular sewer, 510 lin. ft. of 6 ft. circular sewer, 3,050 lin. ft. of lOJ ft. circular sewer, 2,580 lin. ft. of 11 ft. circular sewer, and 800 lin. ft. of 12 ft. circular sewer, with a crossing of Bubbly Creek, and other appurtenances, at a cost of $230,000. D. This project is similar to C, except that the interceptor would cross Bubbly Creek on the line of West 39th St. and follow West 39th St. to the conduit near Eobey St. This necessitates the extension of the Ashland Ave. and Eobey St. sewers across Bubbly Creek. At times of storm, the interceptor would probably flow under head. An overflow weir can be provided at Center Ave. to care for excess storm flow. This project includes about 2,190 lin. ft. of 5i ft. circular sewer, 510 lin. ft. of 6 ft. circular sewer, 2,540 lin. ft. of lOi ft. circular sewer, 2,600 lin. ft of 11 ft. circular sewer, 640 lin. ft. of 12 ft. circular sewer, in addition to 3 crossings of Bubbly Creek, the extension of Ashland Ave. and Robey St. sewers and mis- cellaneous work, at a cost of $250,000. To prevent deposits in the intercepting sewer, under projects C and D, occasional flushings by a small screw pump would be of service. With' a capacity of say 200 cu. ft. per sec, electrically driven, this would cost about $30,000. installed. Of these projects, B appears most practicable, particularly because all the Stockyards and Packingtown wastes would be di- verted from the proposed Center Ave. sewer. COST OF SEWERAGE PROJECTS. The cost of the various sewerage projects described may be summarized in a preliminary way as follows, exclusive of engineering, right of , way, or land charges. A. For the connection of Robey St. to the West 39th St. con- 220 duit and for carrying Ashland Ave. east to the East Arm of the South Pork, approximately $75,000. B. For the complete interception of all sewers from Halsted St. to Ashland Ave. and Robey St., with the exception of the pro- posed Center Ave. sewer and the portions of existing sewered areas diverted to it, and including the diversion of all packing-house , wastes to Ashland Ave., approximately $275,000. C. For the complete interception of all sewers from Halsted St. to Robey St. into West 39th St. conduit, following a route along the south bank of the East and West Arms of the South Fork, approxi- mately $230,000. If the packing-house wastes be diverted to Ashland Ave. for separate treatment, this cost will be increased to $355,000. If the pumping station be added, these figures would be increased by $30,000. D. For the complete interception of all sewers from Halsted St. to Robey St. into the West 39th St. conduit, following a route along West 39th St., wdth branch lines to existing sewers, approxi- mately $250,000. If the packing-house wastes be diverted to Ashland Ave. for separate treatment, this cost will be increased to $375,000. If the pumping station be added, these figures would be in- creased by $30,000. COST OF TREATMENT. SCREENING. Individual screening apparatus for individual firms in the Stockyards and Paekingtown region will require a total expenditure of approximately $150,000. This estimate does not include buildings or any duplicate or reserve installation. It covers only screens, motors, and foundations with a small allowance for sewer connections. In many cases existing buildings would serve, in others new buildings would be required. Collective screening at the main sewer outlets will be less costly, but not quite so effective on account of the breaking down of material in transit. Individual screening will, however, keep all material recovered on the premises where produced. SCREENING PLUS SEDIMENTATION.' Individual screening plus collective settling appear feasible, as well as collective screen- ing and settling. Probably slightly better results can be obtained' with the former, altho the total cost will be somewhat higher. As- suming the new Center Ave. sewer built, and the adjacent sewers relieved, as previously noted, for the treatment works to handle the 221 sewage from Halsted St., Morgan St., the old Center Ave., Ashland Ave., and private sewers, the cost of a sedimentation plant with col- lective screening would be around $600,000, exclusive of legal, engi- neering, land, and right of way, expenses. Omission of the collective screening will reduce this to $560,000. In addition to the costs pure- ly for treatment, remodelling the sewers in Packingtown to divert tO' Ashland Ave. will cost roughly around $125,000. To collect the sewage from Halsted St. and along the river bank to Ashland Ave., thence to the plant, with discharge to the West 39th St. conduit, and the diversion of Eobey St. into the same con- duit will cost about $150,000. No account is taken of the proposed Center Ave. sewer. BEST PEOJECT. If any one project can be called best of the " alternatives suggested, it is the one shown in red on fig. 18. This comprises an intercepting sewer largely for industrial wastes from Halsted St. to the "West Arm, the diversion of all Packingtown from Center Ave. to Ashland Ave., fine screening at the individual houses or firms, sedimentation at the community outlet with a plant built , in Bubbly Creek, the construction of an outfall sewer into the West 39th St. conduit and the diversion of the Robey St. sewer into the same conduit. This is estimated to cost! approximately $985,000. Several slight modifications are possible. It is assumed that the proposed Center Ave. sewer will discharge directly into the Creek. This project handles the wastes as separately as possible with the presence of some domestic sewage, and is flexible with regard to the future. BIOLOGICAL TREATMENT. In order to make the discussion more complete, a brief study has been made of the possibility of treating biologically the industrial wastes from the Stockyards and Packingtown at a point outside of and west of the city limits. This would require the construction of an intercepting sewer westward along the general line of 39th St. or thereabouts to a point in the general region between the city limits and the village of Summit, on a tract of land lying north of Archer Ave. An interceptor for twice the dry weather flow would be approximately 7.5 ft. in diameter, and necessarily would be so far below the ground at the outfall that pump- ing would be required in order to lift the sewage onto the filter beds and secure- sufiicient head to discharge into the drainage canal. It is assumed that the screening and sedimentation will be carried out in the Stockyards and Packingtown in accordance with the recom- mendations previously made herein, and that the sewage thus pre- pared would be delivered to the works. Roughly speaking, the 222 approximate cost of the intercepting sewer, pumping statiofl, sprin- kling filters, and collateral works including an outfall from the works to the drainage canal would be $3,600,000, entirely exclusive of right-of-way, land, engineering, and legal expenses. These figures are not as carefully prepared as those in the preceding pages, and are given merely to indicate what the ultimate solution will cost. They are also subject to revision, in accordance with the results of a long time test still running on the sprinkling filter, which is planned to continue through another summer season. 225 APPENDIX I. LIST OF FIRMS IN THE STOCK YARDS AND PACKINGTOWN. OUTLETS INSPECTED AND TESTED. 1911. Adler & Oberndorf . ' Anglo-American Packing & Provision Co. Catch Basin (A). Armour & Company. 43rd St. (A) 43rd Place (B) 44th St. (C) ■H. Bobsin, — Sausage Casings. H. Boore & Company. Boyd-Lunham & Company. Brennen Packing Company. Chicago Packing Company. Darling & Company, — ^Fertilizers, — Ghie Factory. Friedman Mfg. Company,— Butterine. L. Glick, — Sausage Casings. Henry Guth. G. H. Hammond Company. Catch Basin (A) South Sewer (B) Hine Bros. Company, — Kendering "Works. Independent Packing Company. Libby, McNeil & Libby. Mickelberry Farm Products Company, — Sausages. Miller & Hart. Morris & Company. Hog Plant. 42nd St. 44th St. Ammonia Plant. Northwestern Glue Company ,~Glue and Fertilizer. Peoples Packing Company. Pfaelzer & Sons. Roberts & Oake. Siegel-Hechinger Provision Company. Standard Slaughtering Company. 224 Sulzberger & Sons Company. Grease Sewer through Catch Basin Ked Sewer. Swift & Company. 40th to Ashland (A) 42nd to Ashland (B) Packers Ave. (C) 41st to Center (D) 42nd to Center (B) Wool House (P) Union Stockyards & Transit Co. Western Packing Company. Catch Basin (A) Wash Water (B) Note: — The letters following the designation denote thg individual out- lets examined. 225 APPENDIX II. Report of Test at Plant of ADLBR & OBERNDOEF. June 22 and 23, 191i: PLANT. Adler & Oberndorf manufacture inedible tall-ow and fertilizer, and deal in hides. They gather scraps, bones, etc., from various meat markets, restaurants and small slaughtering houses, and take all the waste, scraps and offal from the slaughtering firm of Peacock and Sheehan, and the casing cleanings and rejected casings from the Western Casing Co. Everything is rendered for inedible grease, and the remaining solids utilized in manufacturing fertilizer. The concern has no evaporator, but claim that their tankage is cooked to a dryness before pressing that leaves practically no tank water, and that the little which reaches the settling basins remains so long that all the grease is skimmed off. The solids from the catch basins are used with the solid tankage for fertilizer filler. DRAINAGE. There are only two wooden catch basins of any size, the rest being clean-out manholes. The total length of flow in the two is estimated at 75 ft., each basin being 4 ft. wide and 18 in. flow depth, baffled with scum boards and an outlet baffle. The flow is usually small. PEACOCK & SHEEHAN. Peacock & Sheehan are slaughterers, renting space from Adler & Oberndorff. Their usual kill is 100 to 150 sheep and 30 to 40 calves per day, killing only a few hours each day. During the test the kill was : June 22, 151 sheep, no calves ^ June 23, no sheep up to 4 p. m., 30 calves. The sewage is principally blood and wash and floor water, pass- ing direct to the sewer. There is no paunch manure, as the paunches are bought whole by Adler & Oberndorf and rendered for fertilizer. WESTERN CASING CO. The Western Casing Company rents ' space of Adler & Oberndorf. They buy green casings from the smaller houses, cleaning and packing them. Their usual run is 3,500 casings a day. The sewage is mostly wash water. There is no catch basin. SEWER AND WEIR. The sewage from these three firnis enters the Center avenue sewer through a 12x12 in. box sewer. A 12-in. weir without end contractions was built in this sewer in a manhole just below Adler & Oberndorf. Readings and samples were taken June 22 and 23 (table 124). 226 bJ _i 03 < J- o Q § n o § s o o I *H P C ■ -a* ; 'S= fS^ ! ■2 J 5J 1 > Oco ■^ T-t NCO §g 1—1 (M coo (NCO OM -*o 000 T-H CD 1 1- f^ 5" ° 1 ■3 -s Eh 1^ Ch h o 02 Sd bH (xi>-: iJ o > 03 ^ 1 COO • . . -r^ JO :8 ooo .•:^ •CO ■ eo O "0 •05 OOOO'^COOOINIMtO- 000000(M00OS«l>O' 3 tH *-t rH CO ^ Wt) • 00 00 •* N O O :* • « O t~ 00 O 00 Q •l>CO i-HOtC^ Ot~COlOI^l>i-lOO-*lOt>OOecoeorHi-Hcsc<5eoc^to(NOi--i>-ic 3 02 -3 1 03 1^. s^ O ■s.g -a -43 ^^a >i c3 % (N (N • ■ •CO :^ CDCi<:D-5*-*00O(NIM »-) i-H »— I ... ooooooo^_____ IM^OO(N-*000(M1N-*QO(N-*00 O (N (M-*00(M^OOOIM s; 237 PLOW. The calculated flow of the 43d place sewer and the chemical analyses are shown in table 129/ SLUDGE. Although sludge is continually removed from the basin, from 6 in. to a foot may always be found on the bottom, deepest at the influent end. This is composed of cinders, scraps of flesh, hides and offal, and paunch manure, and is fairly fresh, with a strong "pig-pen" odor. SLUDGE ANALYSIS. Per Cent. Moisture 58 Volatile matter ,; 26 on dry basis Fixed " 74 Nitrogen 1.4 " Fat 1.7 PERIOD IN CATCH BASIN. The nominal period in the catch basin may be estimated from the flow of the effluent weir (table 130). 44th STREET SEWER. DESCRIPTION. The 44th street sewer is a 24 in. tile sewer, receiving the drainage from the stables, fertilizer factory, wool puUery, part of the oleo house, and from the cooper shop and lumber yard. CATCH BASIN. No catch basin is provided on the main line, but the water from the wool puUery passes through two, both built of timber. One receives the flow from the wool cleaning vats, and the other the flow from the liming vats. The flrst is 47 ft. long, by 4 ft. 6 in. wide, with a flow depth of about -4 ft. There are underflow baffles, extending to a point 24 in. above the bottom of the tank. The second is similar, except that it is 56 ft. 6 in. long. These basins are kept clean. The sludge from the flrst is composed largely of manure and dirt washed from the pelts. Brown in color, with a gaseous odor, it is used for fertilizer. The sludge from the second is largely slaked lime and, wool. Dirty white in color, it has a characteristic lime odor. The wool in it is recovered. WEIR. A weir 2.0 ft. long with end contractions was built in a timber manhole at Center avenue. Readings were taken with a hook gage. READINGS AND SAMPLES. Readings and samples were started May 23d, but owing to a leak in the weir, the readings prior to 2 p. m.. May 24th, were discarded (table 131). 238 •ri •a CI D. m ■S rn T) a'" i A u a fl o 9 02 fc I << CM i 3 o ^ =a ;a Ph o t) o 11 ^ id p^ pjj lU pg "S LE 131. TH ST to 26, 1 1 >° § 3 g5 02 1- f^ ^ o S •3 o H o Hi pq P^ o OQ g I'i 02 |X( — i» u >-5 iS ^ <1 fq <) o <« d g o o o ■a -3 •2 S -*3 >. i^ 03 05 • -00 tOOi • 't- inco 05tO C"3"5 •lO ■ >o •(M ^■* • -(NOO t>to • -mo •CO -lO ■CM -CO ■o> ■(M -O •to .(D • to ,-)l to to 00 00 ■■*(N • MCn ■00 CO CD 00-^ ^00 CD -"f CO -^ Oif* lOO OOCO coco ■<. _. iO»O-^C0^t^(N'<**,-i00r-(T-i-^OC0t^'«:J*t^i-< T-l ,-H rH >-s TtH W S 1> l» -a O m 000^0 CO IN IN ^0. 10 S u 00 CD 6'' t^ (N CD T-l ■^ 6 o 1 SR 03 S " I>i0«10.-l 00 OCD 1000 03 S tS coco t^cD a:> .— 1 JXtO 00 .-1 ^ ■ S IK i-H rH i-H rH i-H CO rH rH rH d M S o S ^ ja °s ^ ^ ^ 000(M0 CO .—1 tH INO P3 ^ S5-^ (M .-1 gco >o D ^js ■" rH .—1 O Ph ft ' ■— ' <1 t- 10 CO-* 1-1 COO t^O 05 ^ §?s 1>00 00 .—1 C^ .—1 g « g i-H .-( i-H (N rH 10 »0 S 1 i (M>-t-*0 1 ■3 COI>-CO00 ^ CO com C3S.-I IN 2 P +3 00 OiiO t-H t^ SS! r- .-1 Tjl s ^ o .-It- ^co CO •^ [i. H T-l r-H .—1 02 1 o 1 Cq T-l COCO i-H TJH •^t-H .—1 c^ J^ CQ 00 00 ooo) a> (N t^ .—1 ;^ a o IN 1—1 COIN «0 ta Tt^CO CO »o 00 CQ .-1 IM I-H CM .-1 I— 1 «0 3 ^ 1^ < m a> ^ t>^00„„ rHl> COIN (N S [5| 10 CO 10 "^"^ ■* Nt: CQrH 1—1 ^ o w O ■1^ ■3 l>l>l>O00 CO 'illN IN CO CO iz; 3 .-1 tH »-l CO i-l CO IN lOCO 1-1 £f .— 1 .—1 IN^ 1—1 H ?3 O s a s a a a a a a a a c3 0! si P, o3 d P, IS 0.03 d a; 00 00 00 00 00 00 00 00 00 00 00 S 00000 S3 H +3 -1^ -(^ -fA -tJ += -*^ -fj -*a a a a a a a a a a a a A ^ ^ ^ d, sj 1« p. IS d !S 00 00 00 00 00 00 0000 00 00 00 ll 0.-IIMCO tH 10 CO l> 03 6 241 periments under quiescent conditions, the major portion of the sus- pended matter settled out in 30 minutes, and in all eases two hours sufficed. On samples from No. 4 and No. 7 a scum formed, showing that some of the suspended matter is very light and greasy, probably the volatile portion. From the analyses, the waste waters from three outlets appear of reasonable quality, as they are not much stronger than average sewage. The other outlets contain at times so much suspended matter that they should be collected in a common basin for settling, with a settling period of at least two hours. Scum boards are re- quired to hold back the grease or floating suspended matter. The basin should have hopper bottoms to facilitate cleaning. 242 APPENDIX VI. Report of Test at Plant of BOYD-LUNHAM COMPANY. June 20 and 21, 1911. LOCATION: The Boyd-Lunham plant is at 45th and Cook streets, west of Eoberts and Oake. Their sewage outlet is to Center avenue by way of 45th street. PLANT. This is one of the smaller packing Houses, doing only a pork business. Dressed, smoked and boiled, and pickled meats are prepared, but no canning is done. Lard, grease and fertilizer are made. Two hundred and fifty to three -hundred men are em- ployed. CAPACITY. The capacity of the plant was given as 250,000 hogs per annum. The kill during the two days of the test was 1,480 and 443 hogs, respectively. The kill usually begins at about 8 a. m., lasting until 4 or 5 p. m. The plant is not operated at night so that the cleaning up practically terminates the flow of sewage. OPERATION. Most of the blood is-^ saved, coagulated and filtered, and added to the fertilizer. All wash and floor water goes to the catch basin. Offal and scraps are rendered for grease, the tank liquid is evaporated for "stick," and the solid tankage pressed and dried for fertilizer filler. All paunch manure is put into the rendering tanks, without being pressed. No ground bone is made, but steam bone is utilized with the tankage. All hair is sold green. SEWERS. The flow from the killing floor, cutting rooms, tank rooms, sausage and fertilizer departments, and the smoke house, passes through the catch basin. Toilets, down spouts, condenser water, etc., drain direct to the street sewer. CATCH BASIN. The catch basin is of timber 21 ft. long by 3 ft. wide, with a minimum flow depth of 2 ft. 7 in. There are four sets of under- and over-flow baffles, the baffles of each set being 12 inches apart. The under-flow baffles are 12 in. above the bottom of the basin, while the over-flow baffles are 5 to 7 in. below the surface. At the effluent end, the water passes over a tight baffle, 2 ft. 7 in. high, and through two i in. mesh wire screens. The basin is said to be cleaned once a week, the sludge being used for tankage. No regular care is taken of the basin, the screens being cleaned only when badly clogged. MEASUREMENTS AND SAMPLES. As no plant discharges 243 o i o m H I « ^ '^■- PO (-H _j^ " s ^ in m "a 9 ?^ o < O N I-. E-i a> O ^ o a (-^ PR o 03 H 03 < I— I w o i .^8 ^ 5 ea ai'S S § 1 i d £ s ■ <1 bfi 1 ." § V t? II ■d to s =M d t3 i a5 S § 3 « 3 g S ^ g >s g fe 3 •a (U X u E (U 1 § -S -a 1 g > p. to 3 03 i E» 1^ E- •sg 13 ■* ■£- 03 ^1 •^6 5^ 0- ' 1 00 10 •* 000 00 OS CO OicO 000 ■*T-t (M to CO OS CO 00 p. ci. 000 SETTLING EXPERIMENTS. Settling experiments with the effluent of the catch-basin show that 60 to 70 per cent, of the total suspended solids will settle out under quiescent conditions. 247 APPENDIX VIII. Report of Tests at Plant of CHICAGO PACKING COMPANY. June 20 and 21, 1911. PLANT. The plant of the Chicago Packing Company is located at 4531 Gross avenue. A general slaughtering and packing business is conducted on a small scale, slaughtering cattle, calves and hogs, and sheep subsequent to June 1, 1911. The products are dressed, smoked and boiled meats, tripe, lard and inedible gi-ease. About fifty men are employed. CAPACITY. The average kill was given as follov7s : Cattle 50 daily Calves 60 daily Sheep 100 per vreek Hogs 150 per week MANUEE. The pen manure is swept up and dumped at Arm- our's, whence it is shipped to the country. All paunch manure, except that from calves, is disposed of likewise. There are no paunch manure separators or presses, but the paunches are ripped open and their contents dumped through a chute into carts. In this way very little escapes. The calf paunches are put whole into the rendering tanks for fertilizer. BLOOD AND EENDERING. The blood is collected, cooked, but not filtered, and then sold to the fertilizer manufacturers. , Lard is rendered, and all scraps and offal, along with the calf paunches, are rendered for inedible grease. The liquid goes to the catch-basin, and the solid portion is pressed and sold as tankage. As in other small houses which have no evaporators,, the tankage is cooked until practically dry. All casings are cleaned and packed. There is a smoke house, tripe room and a hide cellar. All bones are sold green. TABLE 137. NOMINAL ELEMENTS OF CATCH BASIN. Capacity, 320 Cu. Ft. Flow. Period in Basin, Average Velocity, Maximum Velocity, 0. f. p. s. Min. Ft. per Min. Ft. per Min. 0.10 53.3 0.6 1.5 0.20 26.6 1.2 3.3 0.30 17.8 1.8 4.5 248 < O O o I— I O o o 1 oi 1 "^ pc,vJ d *ta a o o "^ '-3 fe ^ ^6 (U 3 K 1 oo 2fe 05,-l -3 ^5 OtO d. P. CXICO o a s ooo 249 SEWERS AND CATCH BASIN. All sewage, except overflow from pumps, condensing water and toilets, flows througli a concrete catch-basin 32 ft. long, 4 ft. wide and about 2^ ft. deep- (water depth). The basin is divided into 3 compartments by concrete under-flow baffles, 8 ft. on centers. The flow space below these is 12 ia. deep. Between these are timber over-flow baffles, each pror vided with a 12 in. lift gate. At the outlet are two i in. mesh wire screens, which- are taken out, singly, when clogged, and cleaned with a steam jet. The screens are said to have been installed about May 1, 1911. "WEIR. A weir was built on the last overflow baffle, just above the screens, with a net length of 3 ft. f in. with 2 ^nd contractions. The maximum flow was 0.27, the minimum 0.19 cu. ft. per sec. 250 APPENDIX IX. Report of Test at Glue Plant of DARLING FERTILIZER COMPANY. June 13 to 15, 1911. DESCRIPTION. The Glue Plant of the Darling Fertilizer Com- pany is on 42d street, one block east of Ashland avenue. Glue, inedible tallow and poultry food are made. Selected bones are dried and sold to the button manufacturers. OPERATION. Bones and fresh meat scraps, bought from mar- kets and restaurants, are collected by the company. As unloaded they are sorted by hand into different grades, the bones being kept separate, and resorted. The thighs or buttocks, leg-bones and ribs, in good condition are saved for the button manufacturers, while rejects are used as "steam" or "soft" bone for making glue. The scraps of hide, sinew, hoofs or tails are used for making glue, while the meat and fat scraps are rendered for grease. The solid tankage is pressed and dried, then ground for poultry food. The liquid is evaporated. The wash- and floor-water is collected and settled under heat inside the building before going to the catch- basin, to extract the grease. CATCH-BASIN. The concrete catch-basin is divided into two sections, both located in the alley between the two main buildings. Each is 3 ft. wide by 2^ ft. deep, with a total length of 120 ft. Over- and under-flow baffles are provided, spaced about 8 ft. apart. The under-flow baffles act only as scum boards, but the over-flow baffles extend to about 3 in. below the top of the water. The sewage enters the catch-basin at several points along its length. The effluent dis- charges through a 20 in. tile emptying into the effluent end of the disused catch-basin on' Swift's 42d street line. A 24 in. weir, with two end contractions, was built in the last overflow baffle. Samples and readings (table 139) were taken during the day only, for two days. The maximum flow was 0.31, the minimum 0.18 cu. ft. per sec. / 251 l.ao 000 A^'i Sgg :5-o « ■fH Cf 11 ^SS (A S> < S fi d ^ II ■* tOt-l p^ tD(N oomoi *J' , (n ^-\ l_^ K '^ HJ J o aj OD Ph a a 1 § ^ .£ OiOiiD E£| o _3 ^8S£S H CO H 1 & 1 l--j ^ g^ PL, 1 05 GOC» CO "^ Oi "" i~^ "-^ iij ^ s _i Q . 60 H s s M ^^§ p o 03 s i—i H ■g ^ ^ ^ T3 1 •43 -sH'* to § -1 10 Ot^ COt-H 00 1— 1 1 1 > iJ ■a C»(NOO ^ 1 05 >0 to T-H -- ol odd BR. E-2 • o •sg. ■o'-S •gJ -2^^ ^"3 a a a oa (U fk ' 1 (n 3 1— I OQ rage p.s. (O '—' • >f^'" > "3 i-J 1 oo CCCO 020 CO. 00 ooo 5~o a>QO OS T— ( o cq coo IMOO t~ CO CO (N do B a o. p. o o ooo SETTLING EXPERIMENTS. Settling experiments with the effluent in a 500 e. e. cylinder show that 28 per cent, of the total suspended solids settle out in 1 hour under quiescent conditions. 254 APPENDIX XI. Report of Tests at Plant of HENRY GUTH. July 14 and 18, 1911. PLANT. This house slaughters cattle and sheep on a very small scale, and is located on Halsted street just south of 39th street. The usual kill is about 20 cattle, 15 to 20 calves, and 30 to 40 sheep per day. Everything is done by hand with few modern appliances. Very little water is used, as the carcasses are simply washed off with a sponge or cloth, as dressed. No blood is saved, but all scraps, paunches, etc., are sold. No by-products are made. FIELD WORK. There is a very small catch-basin. The samples were taken in a manhole. It was not practicable to build a weir, so readings were taken of the water-meter. As there is no evaporation or tank room these readings give a very close line on the sewage flow. Samples and meter-readings (table 142) were taken at 20 minute intervals from 10 a. m. to 4 p. m., July 14th, and from 10 a. m. to 6 p. m., July 18th. 255 \ CM GO o M O H W O g . O 00 O --I o ® a £ S '^ a 1-1 cq J2 3 ■*oo MOO 1—1 tP QOO to CO C<5(M (M05 l>0 1^ pLC«' °.2 _£;> S 00 COCM od a a p. p. o o a a cd C3 OO SETTLING EXPERIMENTS. Settling experiments with the effluent of the Guth plant show that 32 to 70 per cent, of the total suspended solids will settle out in 1 hour under quiescent conditions. 256 APPENDIX XII. Report of Tests on Plant of G. H. HAMMOND CO. April 19 to 22, 1911. PLANT. The G. H. Hammond Co. plant is a typical packing house, slaughtering cattle, sheep and hogs, preparing dressed, smoked and canned meat, and producing a variety of by-products, such as butter, oleomargarine, tripe, soap fats, grease and fertilizer. SLAUGHTERING. In the first stages of the packing house, cattle and sheep are killed, cleaned and skinned. The hog is killed and cleaned and the hair removed. "Whatever digested manure may accrue is saved and sold, whether from hogs, sheep or cattle. The paunch manure contains, however, semi-digested grain and hay. From the hogs, the solid portion of the paunch nianure is used in fertilizer. From the cattle and sheep, the paunch manure is collected into a screw press (or expeller) and compressed to reduce the content of moisture. The dried product can be burned. About 22 lbs. per head of cattle is collected, said to have a fuel equivalent per ton of i ton of coal. The liquid waste and water from the floors contains some paunch manure. This passes into the sewer. The blood is coagulated by heat, and filtered through cloths in a filter press. The liquid effluent is cooked in brick basins (tank water catch basins) outdoors, heated by steam coils. The liquid is pumped into the "stick" stock and evaporated. The solid portion from the tank water catch basins is added to the blood, and sold as blood fertilizer. Any blood reaching the sewer passes through the collect- ing basin (C. B. 1). Offal from the cleaning of casings is rendered, but some finely divided material passes out with the wash water. DRESSING. The scraps are all rendered. The solid portion from the rendering tanks is pressed and dried, mixed with stick, and sold as tankage. The liquid from the rendering tanks is run into the tank water catch basins, eight in number. SMOKE HOUSE. Wash water from the floors is the only waste. CANNING AND TRIPE ROOM. The boiling water from the canneries, and the water from scalding and cooking the tripe enter the first compartment of the long basin. BUTTER, OLEOMARGARINE, ETC. In this department, the fats are hashed and cooked, and settled over night with salt to precipitate the moisture. The liquid is run off to the catch basin, to 257 be skimmed. There is also a compartment where the oleo settlings are skimmed. FERTILIZER. Besides the blood, there are two sources of fertilizer. The manure is dried, ground, mixed, and bagged and sold for lawns. The '>tick" or liquid from the cooking tank, boiled down, is added to the dried tankage, including the cleanings from the hog paunch. The tankage acts as a dryer and base to hold the - liquid. POWER PLANT. Condenser water runs out from the power plant into the south sewer. COLD STORAGE. Pickling liquor and, wash water from the floors are the wastes here. SEWER SYSTEM. The sewerage. of the Hammond Co. plant has three general subdivisions. I. This line discharges directly into the Center avenue sewer. It receives the drainage of the toile.ts in the general office building, kitchen drains, downspouts from the office building and the north side of the canning and packing building, and some of the toilets in the latter. II. The drains from the killing floors (except the paunch manure), the trimming and dressing rooms, coolers, packing and oleo departments, the laundry, and the rest of the toilets empty into the skimming tanks between the two main buildings (Catch Basin I). This is a long, shallow basin, built in eight compartments, each about 60 ft. long by 8 ft. wide, by 2^ ft. flow depth. Each compartment has a separate outlet into a concrete conduit running alongside the basin. The grease and fat are skimmed off and taken in barrels to the tank room. The lower end of this conduit opens into a small screen chamber fitted with a removable | inch mesh wire screen. This discharges into the main catch basin (Catch Basin II). III. The third system receives the effluent of the paunch manure tank, and the condenser water from the power plant and evap- orators. A 24 in. tile is the final outlet into the outlet compart- ment of the main catch basin. MAIN CATCH BASIN. The main catch basin is built of con- crete, 113 ft. long by 17 ft. wide inside, with a flow depth of 3^ to 4 feet, baffled alternately, top and bottom, by timber baffles 16 ft. on centers. The upper baffles extend about 18 in. below the normal flow line, while the lower baffles rise 12 in. above the floor. The floor is flat, sloping toward the outlet. This is of no service, since the lower baffles are tight. At one time this basin was skimmed for grease. 258 SCREENS. Two sets of screens are in place at the outlet end of the main catch basin, both of ^ in. mesh. One set (upstream) is fixed. The other set (downstream) is removable, built in two parts, each 4 ft. wide. Below this, a wooden stop plank forms the overflow weir of the catch-basin. A gate may be opened in this stop plank, with very large flows. CONDENSER WATER. Midway between the two sets of screens is the suction of a pump feeding the evaporators with cooling water. This pump is run continuously while the fertilizer plant is in operation. At night this draws down the main catch basin as much as 24 in., leaving a flow depth as slight as 15 in. above the bottom. BLOWOFF OF MAIN CATCH-BASIN. Directly under the in- take pipe of the centrifugal pump is a 12 inch gate, which by-passes the screens. There was considerable flow through this. During the test the leakage was cut to a minimum with sand ,bags. This gate would permit any sediment on the bottom of the tank to wash out. ' PAUNCH MANURE TANK. The overflow from the paunch manure expellers ia the killing room passes into a shallow concrete basin 10 ft. square, on the South side «f the killing house. This is baffled to make a flow under and over. The paunch manure which settles out in the rapid current is forked out by an attendant and carted away to the dump. A great deal of paunch manure escapes. TANK WATER CATCH BASINS. These are eight in number, built^of concrete, lined with brick, open, each 10 ft. by 16 ft. by 10 ft. deep, with a capacity of 11,000 gallons. Steam coils are run inside the tank, just above the bottom. The tank water is allowed to settle in these tanks for 8 to 12 hours, at a temperature of 150 to 180 deg. Fahr. Whatever grease rises to the surface is skimmed off. The water is pumped out and evaporated to stick. The solid residue is cleaned out and put into the tankage. None of these tanks are said to discharge into the sewer. OUTLET CHAMBER. The overflow weir of the catch basin discharges into a compartment which also receives the 24. in. tile drains from the paunch manure basin, etc. A 36 in. drain carries both flows into the Center avenue sewer. This can be closed by a sluice gate at time of heavy rains. The 10 inch centrifugal pump is then operated, drawing its water from the combined flow. This discharges into the main sewer. WEIRS. Two weirs were built, one. Weir A, to measure the flow through the main catch basin, the other, Weir B, to measure the flow from the paunch manure tank, condensers, etc. Both weirs were built with end contractions, the crest of A being 24 inches long, 259 and of B 12 inches long. Folding rules were set in place to serve as gages. To prevent leakage, sand bags were packed in on the floor behind the weirs. Inuring the first day Weir B developed a serious leakage, which was finally stopped with more sand bags. FIELD WORK. The duration of the test was 72 hours. Samples were collected and the head over the weirs read and averaged ac- cording to the following schedule : ONE HOUR. Between 8 a. m. and 2 p. m. a portion of about 500 c. c. was collected every 10 minutes, and averaged in a gallon bottle for the hour, the weir being read also. TWO HOURS. Between 2 p. m. and 8 p. m., a portion of about 200 c. c. was collected every 10 minutes and averaged in a gallon bottle for 2-hour periods, the weir being read also. FOUR HOURS. Between 8 p. m. and 8 a. m., a portion of about 200 c. c. was collected every 15 minutes and averaged in a gallon bottle for 4-hour periods, the weir being read also. KILL DURING TESTS. The kill during the tests was as follows : Date Cattle Sheep Calves Hogs April 20 850 1577 129 1089 21 558 1319 22 800 ANALYSES. Owing to the large number of samples, only the suspended matter of individual samples was determined. Weighted by the flow, composite samples were made in the laboratory covering typical periods. On these the oxygen consumed was determined, ,and special settling tests were made. The results of the analyses (table 143) show a varying content of suspended matter. The results at Weir A are consistently lower than at Weir B, with the exception of a few samples taken late in the afternoon or at night, when the catch basin was used as a condenser supply. Weir B contains a deal of paunch manure, as well as material probably drawn through from the catch basin by the condenser pump. The highest content on Weir A was 676 parts per million, on Weir B 2148 parts per million. Both figures are high, indicating insufficient settling. CHARACTER OF SUSPENDED MATTER. The character of the suspended matter is greatly different from that in City sewage. The proportion of volatile or organic matter to fixed or mineral matter is very high, ranging from 80 to 97 per cent. OXYGEN CONSUMED. The oxygen consumed is high on all the average special samples, being higher on "B" than on "A." In general a very large proportion of the oxygen consumed is in solu- tion, although occasionally the reverse occurs.' 260 SETTLING EXPERIMENTS. The settling experiments made in 500 c. c. graduates indicate that the suspended matter settles very quickly under quiescent conditions, and that a period of one hour makes a very marked reduction, the percentage reduction varying according to the amount of suspended matter present. From 35 to 73 per cent, was removed (table 146). TESTS ON FINAL CATCH BASIN. Comparative samples col- lected of the influent and effluent indicate very little settling. The results are as follows: April 21, 11 a. m. to noon. Paets peb Million. Percent. Influent. Effluent. Reduction. Suspended Matter: Total 456 412 10 Volatile 400 Fixed.. 56 Oxygen Consumed: ' Total 292 Dissolved 155 Suspended 137 April 21, 3 p. m. to 4 p. m. Suspended Matter: Total : 448 388 13 Volatile 380 Fixed 68 Oxygen Consumed: Total 146 Dissolved 108 .... Suspended 38 ._j_^ .__^_^_ FLOW. To find the maximum flow, the sum of the readings of Weir A and Weir B should be taken. This occurred between 2 :00 and 4 :00 p. m., being 3.41 cu. ft. per second. The next largest flow was 2.87 cu. ft. per second between 1 and 2 p. m. Flows of approxi- mately 2 cu. ft. per second are quite frequent in the working day. This would indicate a maximum flow of about 2^ million gallons per 24 hours, and a flow of several hours duration of about 1%, to 1% million gallons daily. TABLE 144. HYDRAULIC ELEMENTS OF CATCH BASIN. Calculated Calculated Velocity of Flow, Flow in Cu. Period in Basin, Average Flow, Maximum, Ft. per Sec. Minutes. Ft. per Min. Ft. per Min. 0.5 223 0.51 0,79 1.0 115 0.98 1.57 1.5 79 1.43 2.33 2.0 60 1.88 3.14 2.5 49 2.30 3,91 3,0 42 2.70 4.70 3.5 36 3.14 5.56 261 PERIOD IN CATCH BASIN. The normal capacity of the catch basin for a depth of flow of 31/2 ft. is 50,300 gallons, or 6,723 cu. ft. The period in the basin varies with the rate of flow (table 144). A test with a flow of 2.2. cu. ft. per second at 1 p. m., April 25th, showed that some dye reaches the outlet in 15 minutes and the major portion in 20 minutes. The distribution of flow might be improved. SLUDGE. The sludge in the main catch basin^ measured on April 28th, a week after the test, showed an average depth of 0.64 ■ft. The calculated volume was 49 cubic yards. The sludge layer was deeper and denser at the inlet end, and shallower and appar- ently fresher at the outlet end. This was said to be the accumula- tion of a month. The sludge is said to be drained and tised in the tankage. ANALYSIS OF SLUDGE. Sludge taken from the final catch basin on April 28th, when dried, was of light brown color, contain- ing a deal of wood fibre, mineral matter and undigested foodstuff (table 145). It is of high specific gravity, and low moisture content com- pared to sewage sludges, containing a high proportion of fixed mat- ter. The per cent, of fat and organic nitrogen are both extremely low. TABLE 145. Analysis of Sludge from Hammond Catch Basin. Color : Black. Odor : Gaseous. Specific Gravity : 1.18. Moisture : 61 per cent. ^ Volatile matter (dry basis) : 34 per cent. Fixed matter (dry basis) : 66 per cent. Nitrogen (dry basis) : 0.8 per cent. Pat (dry basis) : 1.89 per cent. CLEANING MAIN CATCH BASIN. The basin was cleaned on April 29, 1911. After the water was drained down to the level of the bottom baffles, the sludge was shoveled out. During cleaning, the emergency 12-inch gate was op'ened about two inches. All the liquid not pumped to the driers went out through the gate, washing away all the light sludge near the screens. SCREENS. The placing of the screens is disadvantageous from a settling standpoint, as the pump suction draws the water through the entire area: of the screen. Such coarse screens are of little service, particularly if the basins be cleaned frequently. They should be m duplicate. The clogged screen should be lifted, cleaned and re- 262 placed, tlie screenings being removed. As operated at present, the screenings fall back into the basin. SUGGESTIONS. To improve the existing plant, certain changes are desirable, particularly in operation, from the individual stand- point. 1. It was expected in 1911 that the paunch manure would be retained by additional presses, and settling on the stripping floor. If done, this has not proved adequate, and a five mesh screen or a settling basin, or both, should be provided for the paunch manure sewer. 2. The reservoir for condenser water should be separate from the catch basin, to prevent flushing material through. It is feasible TABLE 143. TEST OP G. H. HAMMOND CO. PLANT. April 20 to April 22, 1911. Time of Wei kA Wei rB Suspended . Suspended April. ^ Sampling. Flow Matter, Flow, Matter, Cu. Ft. per Pariis per Cu. Ft. per Parts per Sec. Million. Sec. Million. 20 12 to 1 p. m. 0.63 372 0.54 1428 Ito 2 1.18 676 0.79 1664 2 to 4 , 1.36 396 0.40 1548 4to 6 0.94 368 0.48 1576 6 to 8 0.69 296 0.50 960 8 to 12 Mdt. 0.09 . 292 * 300 21 12 to 4 a.m. D 308 * 132 4 to 8 D 180 * 404 8 to 9 0.32 188 0.27 1544 9 to 10 0.88 416 0.51 1320 10 to 11 1.16 344 0.54 1288 11 to 12 Noon 1.28 412 0.69 2148 12 to 1 p. m. 0.74 500 1.31 884 Ito 2 1.34 468 1.53 1256 2 to 4 2.01 388 1.40 1160 4 to 6 0.90 328 0.95 308 6 to 8 D 216 0.71 228 8 to 12 Mdt. D 292 0.63 264 22 12 to 4 a. m. D 200 0.53 388 4 to 8 D 200 0.64 244 8 to 9 D 404 0.47 340 9 to 10 D 364 0.45 300 10 to 11 D 368 0.42 340 11 to 12 0.34 378 0,49 516 12 to 1p.m. D 360 0.42 416 Ito 2 D 476 0.44 544 2 to 4 0.10 370 0.44 480 * Weir leaked. D Catch basin drawn from below crest of weir. 263 to use the present basin as a storage basin and put in the additional settling required on the joint line. 3. The roofs, toilets and human waste should be separated, and not pass through the settling basin. 4. The construction of a settling basin to care for the whole discharge, unless a common settling basin be built at the outlet of the Center avenue sewer. TABLE 146. SETTLING EXPERIMENTS IN LABORATORY. Made in 500 c.c. Cylinders. P A.HTS PEI I MlLUO N. Sample No. BV. BVI. BVII. AVIII. AIX. AX. ORIGINAL— Suspended Matter: Total 1612 1488 124 92 478 138 340 434 396 38 232 138 94 972 896 76 92 360 139 221 634 588 46 235 139 96 268 256 12 96 156 74 82 148 142 6 111 74 37 468 444 24 95 256 141 115 256 244 12 ■181 141 40 472 432 40 92 240 130 110 228 222 6 179 130 49 240 Volatile 232 Fixed 8 Volatile (per cent, of Total) Oxygen Consumed: Total 97 122 Dissolved 68 Suspended. .- 64 SETTLED LIQUID— Suspended Matter: Total 124 Volatile 124 Fixed Oxygen Consumed: Total 109 Dissolved .' 68 41 PERCENTAGE REDUCTION BY 1 HOUR QUIESCENT SETTLING— Suspended Matter: Total. 73 73 69 51 72 35 34 39 35 57 45 45 50 29 55 45, 45 50 29 65 52 49 85 26 55 48 Volatile. . 46 Fixed. 100 Oxygen Consumed: Total 11 Suspended. . . 24 Note. Composite samples are made up as follows: From samples collected on BV. April 21, 8 a. m. to noon. Weir B. BVI. April 21, noon to 4 p. m. Weir B. BVII. April 21, 4 p. m. to Apr. 22, 8 a. m. Weir B. AVIII. April 21, 8 a. m. to 1 p. m. Weir A. AIX. April 21, 1 p. m. to 4 p. m. Weir A. AX. April 21, 4 p. m. to Apr. 22, 8 a. m. Weir A. 264 TABLE 146— (Continued). , SETTLING EXPERIMENTS IN LABORATORY. Made in 500 c. o. Cylinders. If 4.BTS PBI I MiiiUC N. Sample No. BXI. AXIL AIII. AIV. BI. BII. ORIGINAL— Suspended Matter: Total 372 312 60 84 174 110 64 250 218 32 128 110 18 438 352 86 80 190 141 49 248 234 14 149 141 8 400 380 20 95 228 145 83 224 204 20 177 145 32 296 276 20 93 164 113 51 176 156 20 132 113 19' 1416 1264 152 89 392 132 260 388 344 44 200 132 68 372 Volatile 348 Fixed 24 Volatile (per cent, of Total) .... Oxygen Consumed: Total 92 138 69 Suspended 69 SETTLED LIQUID— Siispended Matter: Total. ... .... 126 Volatile 114 Fixed 12 Oxygen Consumed: Total 96 Dissolved 69 27 PERCENTAGE REDUCTION BY 1 HOUR QUIESCENT SETTLING— Suspended Matter: Total Volatile Fixed : . Oxygen Consumed: Total Dissolved Suspended 33 43 44 41 73' 30 33 46 44 73 47 84 71 26 21 62 20 49 72 84 73 63 74 66 :67 50 31 61 NoTB. Composite samples are made up as follows: From samples collected on , BXI. April 22, 8 a. m. to 4 p. m. Weir B. , AXIL April 22, 8 a. m. to 4 p. m. Weir A. AIII. April 21, 1 to 4 p. m. Weir A. AIV. April 21, 4 p. m. to Apr. 22, 8 a. m. Weir A. BI. April 20, 12 noon to 8 p. m. Weir B. BII. April 20, 8 p. m. to Apr. 21, 8 a. m. Weir B. 5. The present catch-basin, is capable of slightly improved operation. a. The plug outlet valve should be kept closed. b. The basin should be cleaned very frequently to prevent putrefaction. V 265 c. The screens should be built in duplicate, with a trash basket at the bottom. ■" d. ■ Distribution may be improved by a baffle at the inlet end. 6. In remodeling the present grease skimmers, a basin easier to dean can be devised, — with a false bottom. If graded sand, covered with sawdust or an inert substance like cocoanut fibre matting be used, this can be scraped and the fresh sludge removed more cheaply than by the present method of hand bailing. Duplicate basins are advisable. 266 APPENDIX XIII. Report of Tests on Plant of INDEPENDENT PACKING CO. July 11 and 12, 1911. DESCRIPTION. This plant is at Halsted and 41st streets, out- side the yards, in size and operations being similar to the Pfaelzer plant. Cattle, calves, sheep and hogs are slaughtered. Dressed and smoked meats, lard, grease, tripe, sausage and commercial fertilizer are prepared for market. OPERATION. The blood" is coagulated, filtered, and used in fertilizer. Offal and scraps are rendered for grease. All tank water goes to the tank water basins and is finally evaporated. Solids are pressed, dried and ground for tankage, to be used for fertilizer filler. Pen and paunch manure are both shipped out, the paunch manure being first pressed. The operations here closely resemble those at the Hammond plant. About 200 men are employed. CATCH BASIN. The entire flow of the plant, except that from the tank room, goes to the sewer through a catch basin built of rein- forced concrete 60 ft. long by 9 ft. 10 in. wide, with a nominal flow depth of about 3 ft. 10 in. (table 147). There are four sets of baffles, each set consisting of one under- and one over-flow baffle, 15 in. apart. The underflow baffles are of concrete, and extend to 6 in. above the floor of the basin. The overflow baffles are made up of 2 in. planks dropped into guides formed of channel irons set in the concrete walls, and are 3 ft. 3 in. high. The flow enters through a 12 in. pipe at a comer of the influent end, and flows under a wooden baffle built across this corner. At the effluent end there is a plank scum board extending across the tank and 15 in. from the end. The effluent is taken off by a 12 in. tile at the surface. TABLE 147. ELEMENTS OF CATCH BASIN. Capacity, 2260 Cu. Ft. Max. Velocity- Flow, Nominal Period Av. Velocity, (Under BafSe) 0. f. p. s. in Hours. Ft. per Min. Ft. per Min. 0.25 2.5 0.4 3.1 0.50 1.26 0.8 6.2 0.75 0.84 1.2 9.3 267 >. += ^ o a ^3 oo g . ^ ^ cd KIU3 ■* ■ ^ ca s li ' ^J§ g J 6 g o ^ o g og S3^ i-H i-H 55 oo INTO 10<0 Wl(N (NM ^3 1^ ••3 t cqcD 1— ( 1—1 CO §8 r-l CO §§ oo as p. p. ■*rtH S3 aa C3 Id OOO r-4 i>oo r-lTH 271 The water from the cooking vats enters a receiving tank, 40 ft. long by 5 ft. wide, 4 ft. deep. The grease rises to the surface and is skimmed off. There are scum boards, but no flow baffles. The effluent passes on a wooden trough to a grease skimming basin about 20 ft. long by 6 ft. wide, 2 ft. deep, provided with scum boards. The flow then enters the main catch basin, 50 ft. long by 4^ ft. wide, with a water depth of about 2 ft., baffled at top and bottom every i ft. The baffles are arranged in sets, the overflow baffle being be- tween two underflow baffles which are about 15 in. apart. The under- flow baffles are raised 1 ft. off the floor. Normally the overflow baffles come just below the surface (table 149); A weir 4.5 ft. long, without end contractions, was built on one of the overflow baffles. Readings (table 150) and samples (table 151) were taken for two days during the working hours only. The samples were collected from the outlet of this basin. The flow from the condensers and boiler room with the wash water, join the main sewer below the catch basin, passing through a small basin about 20 ft. long by 6 ft. wide, with a flow depth of about 4 ft. This is floored over by a driveway. Below the junction of the two mains there are two so-called grease traps — ^really man- holes — about 4 ft. square. The total flow was not measured. 272 APPENDIX XV. Report of Tests at Plant of MILLER & HART. June 19 to 21, 1911. DESCRIPTION. This is tne of the smaller packing houses, doing only a fresh pork business. No meat is smoked or pickled. The usual killis about 3,000 hogs per week from noon to 4 p. m., no killing being done on Monday or Thursday. The solid tankage, including the sludge from the catch basin, is sold to fertilizer manu- facturers, without further treatment, as No. 1 Tankage. As there are no evaporators, the tank water discharges into the catch basin. The grease skimmed from the basin is rendered and sold as inedible grease ; 80 meii are employed. SEWERAGE. The main flow is through the catch basin. Be- '' sides the tank water, this receives all the flow from the killing floors, wash and floor water, and most of the blood. The overflow from the reservoir, ice-machine and vacuum pumps empties into the street sewer just above the catch basin outlet. Samples of this flow show a clear water. The toilets and scald water have an outlet below the catch basin. The scald water vat holds about 20,000 gallons, and is emptied once a day. CATCH BASIN. The catch basin is built of reinforced con- crete, 45 ft. over all, 4 ft. 6 in. wide, with a flow depth of 3 ft. 6 in. The effluent is discharged by a 12 in. bell siphon, operating in a discharge chamber 9 ft. .6 in. long. Separated from the rest of the tank by a tight oak partition. This makes the net length of the tank 35 ft. (table 152). The inlet of the basin is a 10 in. tile pipe discharging at the surface. Two feet from the influent end is a concrete overflow baffle, 30 in. high. Two concrete overflow baffles are built in the settling portions of the basin, and another just beyond the oak partition, all 6 in. thick, with a flow opening of TABLE 152. ELEMENTS OF CATCH BASIN. Flow, 0. f. p. B. Calculated Period In Minutes. Av. Velocity, Ft. per Min. Max. Velocity, Ft. per Min. 0.25 0.50 1.0 36 18 9 0.95 1.90 3.80 6.6 13.3 26.7 273 n Pi I o !2 O ^- (N O I O o O >1 f +3 d "-) s u '■ «' cd M O < 03' ••~t a g cu CO (H d c3 f^ 1 g <1 2 C3 g 0^ . "^ i-g o m s "B p. § R § § i e H o _2 h 1 1 (^ 1 "O ffi .a ^ f-H s ■ 4^ ^ J ^ 3 13 ^ s f> ,1 ,. oa 1 ^ P^'^. u '-i' d o o -O'-fS O " , 1 -tJ _M alini as aCO i " c3 .FH 03 fl a> o 1 4 g o" C5 S g ■73 § "^ p. g Pi 1^ 1 0) 1 o p< d 02 i 1 ■a 4^ o H . T3 (B .a j; Ph S ce s :S ffl 3 o t> & 3 03 1 ^ tn 1 "^ • fM"*: u "Bg 13 '^ f23 i s p ooo- 3 u:)Tt< t^co (N (MtfXM (M'*- (M lOOi-lt^oO 0 C<5 o> IXNOOWJCOco cDioNejooS 00 CO Oi CD CO -5^ coco -* 0-* OOtHOO o n a a a a d o p. * O. P, C3 o ■* ""^r>n 00 CD 1^ CM s l-l Q Ot-H s a <« a 3 (M ftoo-* o. i-H •* 00 d 0»CCD CDCD t^ P T— I T-i M ■a o a 2^ ^ 03 cj 44 O ^ C3 03 tu O a £ a 4 ^ o S3 4^ g' . "^ o a: S "S p. 9 § 1 OJ 3 i 6 3 Ph 9 m 0) i O 1 T3 OJ .H ■ |i( te 1 o S 1> Pi ^ ™ 1 ^ s^: u 'Bg T3'-3 o o •S a; fe^ £d i i 1 ft i-s ooe MOQ- lOOO ICOi-HpS Cv3r-lT-H »-( C^ -5 (Mt-hi-hn >-i NIO'^ O5Q0 O 00 i-H O »-l lO CC lOCOCC CO»-H CO 3 OCDOO-^ O H003CO(NOS -S ccooos ■*eao'*00'^ OiCO O) CO Oa Csl CO CO o o o o o o TjH 00 00 Tj< 00 Cfl a a a a W^ 00 00-^00 281 SETTLING EXPERIMENT. A test made on the average sample collected between 12 and 2 p. m. on June 15tli, showed the following reduction of suspended matter in 2 hours : Parts peb Million. Before After Percentage Description. Settling. Settling. Reduction. Suspended Matter: Total 404 300 26 Volatile 360 272 24 Fixed 44 28 36 HOG HOUSE. PLANT. The business carried on is the killing, dressing and curing of pork, as well as the preparation of by-products, such as the rendering of grease and lard. The capacity is 1,500 hogs daily on the yearly average, with a maximum kill of 5,000. During the .test, June 13 to 15, the kill was as follows : Date. Hogs. June 13 2,902 " 14 841 " 15 2,058 SEWEEAGB SYSTEM. The plant is drained by three lines of , sewersi One receives the toilets, discharging direct to the Exchange avenue sewer. The other two conduct the waste into the last catch basin, where the sewage was sampled before entering the Exchange avenue sewer. Subsidiary grease skimming basins are provided on each line, 5 on one and 1 on the other. CATCH* BASIN. The catch basin at the hog house is built of wood, 26.5 ft. long by 4 ft. wide, with a nominal flow depth of 2.25 feet. During the test the flow depth averaged about 3 ft., as the crest of the weir was 2 ft. 11 in. above the bottom of the basin. The weir was 3 ft. wide with 2 end contractions. There are 6 baffles equally spaced, extending down to about 6 in. above the bottom; 3 screens are provided al; the outlet, one of %-in. mesh, and two of 3^-in. mesh. During the period of the test the larger mesh screens were in front of the small mesh. CLEANING SCREENS, During the test the screens were cleaned twice a day by lifting one at a time. The matter coUected was dumped on the ground and carted away to the tank room. The amount was small. There was considerable leakage around the screens, large chunks of material appearing below, apparently larger than the mesh of the screen. 282 PERIOD IN CATCH BASIN. The flow in the final catch basin is rapid, and undisturbed by any pumping. The nominal period may be calculated from the flow over the outlet weir (table 158). TABLE 158. ELEMENTS OF CATCH BASIN. Flow, Cu. Ft. per Sec. Calculated Time in Basin, Min. Sec. Calculated Average Velocity Ft. per Min. Ca,lc\ilated Maximum Velocity, Ft. per Min. .0.50 1.00 1.50 2.00 10—48 5—33 3—47 2—53 2.5 4.8 7.0 9.2 15 30 45 60 MANURE. Most of the manure is saved. The hog paunch ma- nure is used for filler in fertilizer, being separated and pressed, but a deal escapes to the catch basin by the overfiow. FLOWS. The flow at the hog house is given in table 159, being calculated from average readings taken every 20 minutes. The maxi- mum average flow is 1.23 cu. ft. per second. At no time was a zero flow observed. TABLE 159. FLOW OF HOG HOUSE, MORRIS AND CO. Flow, Cu. Ft. June. Time. per Sec. 13 12 to 2 p.m. 1.02 Tuesday 2 to 4 p. m. 1.09 4 to 8 p. m. 0.69 8 to 12 Mdt. 0.36 14 12 to 4 a. m. Not taken Wednesday 4 to 8 a. m. Not taken 8 to 10 a. m. 0.89 10 to 12 M. 1.08 , 12 to 2 p. m. 1.23 2 to 4 p. m. 0.89 4 to 8 p. m. 0.58 8 to 12 Mdt. 0.31 15 12 to 4 a.m. 0.22 Thursday 4 to 8 a. m. 0.47 8 to 10 a. m. 0.95 10 to 12 M. 0.95 12 to 2 p.m. 0.95 2 to 4 p. m. 0.95 SAMPLES. Small portions were collected every 20 minutes day and night. From 8 a. m. to 4 p. m., about 500 c. c. was collected every 20 minutes, and averaged every 2 hours. From 4 p. m. to 8 a. m. about 250 c. c. was collected every 20 minutes, and averaged every 4 283 >> ooooo • a ?S^^S§S! : < " ce ■fH a; V o SS^"=^'*'* EQ CO fl in CO 1-1 zo ^ pR S g •< s o fl .■a ^ 11 "-1 ■* i-H ec. 8 =8 1 ■^1 CO 00O5O5 lot* O 1 ■g s. S g i 1 1 Sg-^ CO OiO(N o g S) fe- i ^ o -3 tO«(N00 00t~ 1-) ^ssjgag g§ en U3 tH TABLE FLOW CO S^SSJ^g 1 t^ r-li-H i-H B 1 S 5 "-5 (^ ^ 1 S SS ;S! SS £- JS O CQ OQ CO t^ lO OSr-t.OOCO 00 O 1 S S f> GQ 1 >^ 1 1 SF2S^SS3 o OSt-iOt* o B 1— 1 »— I iJ fe^ggSSg [i,.^ O doT-iooo o s . a a ^ a *s d o 5 ^o o P.03 p,a IS ^00 00-* P.00 00 d CO CO ■*■*■* to 3 1— 1 T— 1 t— t tH T— 1 *-( i CS ft » - 284 hours. Composite samples were made up in the laboratory, based on the average flow, and grouped in accordance with the flow and phys- ical appearance of the field samples. ANALYSES. The results of the analyses of the composite sam- ples are given in table 160. SETTLING EXPERIMENTS. A fresh sample was collected on June 19th for experiment, under quiescent conditions. The amount of sludge collecting at the bottom of the glass indicated that practic- ally all the settling suspended matter came down in the first hour. TABLE 161. REDUCTION OF SUSPENDED MATTER. Pakts per Million. Dbsoeiption. ' Before Settling. After Settling. Percentage Reduction. Total 1264 1060 204 468 408 60 63 Volatile 62 Fixed 71 PEEIOD IN BASIN. The calculated period in the present final basin is around 5 minutes, and the actual period much shorter, so that practically no settling occurs. The baffles are likewise so placed that settlings are swept along and out. SCREENS. The usefulness of the present screens is practically nil. Spaces of one inch or more in each side of the screen slides, and underneath, allow any large solid matter to pass. Chunks of fiesh, hide, hair, etc., are visible plainly in the fiow to the sewer below the screens. These are not included -in the chemical analysis. 28'5 APPENDIX XVII. Report of Tests on Plant of NORTHWESTERN GLUE COMPANY. June 22 and 23, 1911. PLANT. The Northwestern Glue Co. manufactures glue, white and brown grease, inedible tallow and neatsfoot oil, selling the solid tankage to fertilizer manufacturers. No killing is 'done. Fresh stock, scraps, bones, hoofs, etc., are bought from the various pack- ing houses. The sewage consists largely of wash water, the over- flow and liquid from the cooking vats, with a deal of condenser wa- ter. The tank water is said to be evaporated. CATCH BASINS. There are two timber catch basins one 13 ft. long by 7 ft. wide inside, with a flow depth of 3% ft. and a longi- tudinal baffle, on each side of which are 4 sets of under and over- flow baffles, making a total of nine sets, including the one at the end of the longitudinal baffle. There are no screens. The effluent enters a second basin 14 ft. long by 6 ft. wide, having a maximum depth of only 12 in. This has four sets of baffles, which act merely as scum-boards. Below this basin, along the sewer, are two so-called catch basins, or clean-out manholes, 6 ft. square, with a flow depth of 12 in. WEIR AND SAMPLES. A 2-ft. weir with end contractions was built on the overflow baffle at the effluent end of the first basin. Readings were taken every 20 minutes, the samples being taken each time at the last clean-out manhole (table 163). PERIOD IN BASIN. The settling period in, the first catch basin may be calculated from the flow over the weir. The maximum velocity is taken as the velocity under one of the underflow baffles, with its lower edge raised 4 in. off the floor. ANALYSES. Composite samples were made in the laboratory for each day. TABLE 162. NOMINAL ELEMENTS OF CATCH BASIN. Capacity, 317 Cu. Ft. • Mow, c. f . p. s. Period in Basin, Min. Av. Velocity, Ft. per Min. Max. Velocity, Ft. per Min. ' 0.10 0.20 . 0.30 53 26.5 17.6 0.49 0.98 1.47 5.2 10.4 15.6 286 UJ < >» J+; OS O 1 o -i O a 1 il pi] 1 1 22 (N COKI H h p^ 1 H £ fl 1 o ■a ooo Pi ^ .f^ ^ "^ o 2 CO [x, (N -OW 22 and 1 -? Pli o Ph W H § . ^ I >i 4J 7 2U 5 03 CS d »'3 S o § fii f^ 5 2 o f^ S If TJ g-S o. m s ffl" p. 1 ■ fl 1 1 s o o CG i 1 (S •i 1 •a 0) ^ ^ « ■§ ^ a) ■s "3 "d > 02 1 -M 1^ E-: o •sg tj '-{s fS3 1 1 03 fi >^ oo CISCO !Se coco OU3 66 1> « T-l r-100 a B Ad ^ p. 289 APPENDIX XIX. Report of Tests on Plant of LOUIS PFABLZEE AND SONS. June 27 and 28, 191l'. PLANT. The Pfaelzer plant is outside the yards ( at Halsted and 40th streets. A general packing business is carried on, handling fresh and. smoked meats, lard, grease, oleo stock and f ert^izer. The plant is new, built in 1910, and is housed in one building. About eighty men are employed. CAPACITY. The nominal daily capacity was given as— Cattle ■ 200 Sheep 200 Calves 20 Hogs 150 BLOOD, EENDERING, ETC. The blood is collected, coagu- lated and filtered, the solid part being used in the fertilizer and the liquid being run into the catch basin without Evaporating. All scraps of fat, offal, etc., are rendered. The solid tankage is pressed and dried, but the liquor is not saved. All casings are cleaned and packed, but no sausage is made. There is a smoke house, but no tripe room. MANUEE. All pen and' paunch manure is shipped out. The paunch manure is pressed, the water from the press going to the catch basin. CATCH BASIN. Except for human sewage, all the waste, in- cluding the floor and wash water from the killing and cutting floors and tank rooms, scald water, paunch manure overflow, part of the blood, and the condenser water, goes to the catch basin. This is concrete, built in the basement of the building, "U" shaped in plan, with a walk between the two parts. The inside dimensions of each TABLE 165. NOMINAL ELEMENTS OF CATCH BASIN. Capacity, 860 Cu. Ft. Flow, Period in Basin, Av. Velocity, c. f . p. s. . Min. Ft. per Min. 0.10 ' 143 .52 0.20 , 72 1.04 0.30 ' 48 1.56 290 UJ -I ea >> ."S [c ^i ^ o d .1-1 (D g gj O i S 1 O H > M 1- S-: o ■« d o o TS-43 o u •X a fea t^6 s ea I 1' if ^3 i-HIN g?5 ;$8S -S S5? SB da ooo i^g^ 291 half are, length 39 ft. 6 in., width 3 ft. 6 in., and flow depth 3 ft. The total length of flow is 82 ft. There are no screens. The effluent flows over a tight wooden baffle across the end, out through an 8-in. tile in the floor, which empties into the Halsted street sewer. There are scum-boards extending a few inches below the surface. As the bagin is entirely in-doors the temperature is at all times very high. EEADINGS AND SAMPLES. A 3-ft. weir, with end contrac- tions, was built on the effluent baffle. Samples and readings were taken at 20-minute intervals during the day hours on June 27th and 28th. ANALYSES. In the laboratory, composite samples were made up for each day (table 166). No settling experiments were made. 292 APPENDIX XX. Report of Tests at Plant of SIEGEL-HECHINGER. July 19 and. 20, 1911. PLANT. In the Siegel-Heehinger plant, located at 38tli place and Gage street, about 600 head of cattle and 200 calves are slaugh- tered weekly and dressed for the local trade. The only by-products manufactured are inedible tallow and tankage, which is sold green. No evaporator is used, the tank liquid going direct to the catch basin. The blood is collected and sold after being cooked. All the wash and floor water, bile, etc., goes to the catch basin. The cattle paunches are ripped open and the manure sent through a chute to a wooden tank over the catch basin where the water is allowed to drain off. The manure is then hauled away. CATCH BASIN. The catch basin is built of concrete, 34 ft. long by 4% ft. wide, with a nominal flow depth of 27 in. Spaced about 6 ft. apart are scum boards, and wooden overflow baffles 24 in. high. There are no screens. WEIR AND SAMPLES. A weir 2 ft. long, with 2 end con- tractions, was built on an overflow baffle (table 167). Readings and samples were taken during two working days, the samples being collected from a small manhole just below the basin (table 168). The sewage flows into the 35th street sewer. SETTLING EXPERIMENTS. In settling experiments on the effluent of the catch basin 70 per cent, of the total suspended solids settled out in oile hour under quiescent conditions. TABLE 167. NOMINAL ELEMENTS OF CATCH BASIN. Plow, c. f. p. s, Period in Basin, Min. Av. Velocity, Ft. per Min. 0.05 0,10 0.20 115.0 56.7 28.7 0.30 0.59 LIB 293 o iz; o s O O liJ S ^ o 1-1 ■ ■ c^ ^ p "^ o o 1-:! o >> +3 « o S9 2S 03 rf. io« M o T-l < d $■§ "^g? s C3 ? -g k i,2 CO lO fcf-^ ^lO og . "^ mii IffllN =gg O l-H T-ll-l 1 ft >:l J o h f^ m & PM o ^ 't-( (M ^ ■ g§ B -d N O J J>.op tj (i< d ^ 1 CDO a >OCD •^ -^-^ .o . s > m* Si CC • "3 QOO -g Ofl^ o iCCD H t— 1 p. °° 1 "^ 4 ss s- do u a a «4H C Pt d o C Th^ T3'-f o 9 o o 'C ^ ^ ^1 a a c3 d OOO ^cno i o: 51,-I(M P ^ 294 APPENDIX XXI. Report of Tests at Plant of STANDARD SLAUGHTERING CO. (Eli Pfaelzer.) July 13 and 14, 1911. PLANT. In the Standard Slaughtering Co. plant at 40th and Butler streets about 600 head of cattle are killed and dressed week- ly. No calves, sheep or hogs are handled. All meat is sold fresh. The only by-products are grease and tankage, the latter being sold green. The blood is cooked and pressed dry, beiag sold to the fer- tilizer manufacturers along with the tankage. Both pen and paunch manure are shipped. There are no manure presses. CATCH BASIN. The so-called catch basin is a large manhole, about 8 ft. long by 2% ft. wide, flowing about 24 in. deep. There are three overflow ba£3es and scum boards. At the outlet is one ^-in. mesh wire screen. "WEIR AND SAMPLES. A weir was built on on^ of the bafiBles with a crest 1.5 ft. long, with two end contractions. Sainples and readings were taken during two working days, the samples being col- lected below the scum (table 169). 295 o u o H W O Q 12; g O H I Ph o s - ^ < I- i-s O i 1-3 >, ^ ^ ■ ^ < d tr^ 0) d -0; to t^ d 1 g a 2 d .34' (D S II t3 !5 02 § p. 1^ a ^ § c3 _2 !k 02 1 i 1 ^ ■d u .H ^ (i( "^ S a5 -g tl 13 "o t> 3 02 •a ^ ta 1^ S*-: •« a s ■tf '-P .as Ssg ^53 i s R :§ • o ^g 1 g?2 ^f2 CO to .* r-l ^^ II 88 i B ftp. Ttl-* .S.S a a C3 .^ 00 T— i — 3 CO ^ 296 APPENDIX XXII. Report of Tests on Plant of SULZBEEGEE SONS CO, May 12 and 13 and June 29 to July 1, 1911. LOCATION. The plant of the Sulzberger Sons Co. is located to the west of the Yards and Ashland avenue, lying between Ashland avenue and Eobey street, just north of 42d street. PLANT. The Sulzberger Sons Co. is a packing house of the large type, slaughtering hogs, sheep and cattle, preparing dressed, smoked and canned meat, and producing a number of by-products, such as oleomargarine, tripe, soap fats, grease and fertilizer. SEWEES. The sewerage system of the Sulzberger Co. has two separate divisions, one known as the "grease" sewer, the other as the "red" sewer. There is a 30-in. outlet to Ashland avenue sewer, common to both, and an outlet direct to Bubbly Creek at the west of the plant. G-EEASE SEWBEAGE SYSTEM. This system drains all the slaugh]tering floors, trimming rooms, packing, rendering, oleo, lard and sausage departments, as well as the bone house and pork coolers. The outflow of the individual departments or floors passes through skimming basins. The collective discharge is through a concrete catch basin, which empties into the red sewer. EED SEWBE. The red sewer receives practically all the sew- age not containing grease, including the downspouts, toilets, ware- houses, a large proportion of the wash water and water from the con- densers and the stock pens. Whenever the stock pens are flushed with a hose, a deal of manure reaches the sewer. The water from the brine overflows, hide room, casing department and paunch manure outflow, as well as the lard, sausage, ham cure and smoke house all drain into this system. This system discharges direct into Ashland avenue sewer without any treatment. CATCH BASIN. The final catch basin at the outlet end of .the ' ' grease ' ' sewer is built of reinforced concrete, 8 ft. wide by 100 ft. long, with a flow depth of about 3 ft., baffled every 10 ft. 8, in. with baffles rising 2 ft. 6 in. above the bottom. Up-stream from all but the first compartment is a scum board "extending down within 6 in. of the bottom. Hence surface accumulations are held back, and cooled, but all settling particles are swept along through the basin. 297 The first two compartments have no screen board, but retain the heaviest particles by the bottom boards. PUMPING-. The catch basin supplies a condenser pump, which draws from the last compartment. As the tests were run in the day- time, there was an excess flow over that required by the pump. This practice undoubtedly disturbs the catch basin. The pump supplies the drier-condensers, the final flow entering the red sewer. SCREENS. Prior to April 10, 1911, only one screen of %-in. mesh was in place just inside the outlet baffle. The suction of the pumps was also protected by screens. A sluice gate on the bottom was kept open to allow any accumulation of solid matter to wash out. During the test four screens were used, the first three of wire of %-in. mesh ; the last built in two halves, one of wire i/4-in. mesh, the other of boiler plate with %,-in. openings. The last set alone is pro- vided with handles for lifting. At present (1911) they are being cleaned with scrapers by two men, the material removed being pushed back into the basin. WEIRS. For the purpose of the tests, weirs were built at the inlet and outlet ends of the basin by placing thin-edged crests on the top of the first baffle and the outflow baffle. The first weir was without end contractions. Owing to a handle projecting in the mid- dle of the second weir, it was considered to have two end contrac- tions (table 172). ANALYSES. With the large number of samples, only the sus- pended matter in individual samples was determined. Weighted by the flow, special composite samples were made in the laboratory cov- ering typical periods of the test, on which the oxygen consumed was determined. CATCH BASIN OUTLET. The analyses of suspended matter at the outlet of the catch basin show a content somewhat lower than the highest found on the preliminary short time test of 1 hour. The content of suspended matter averaged from 668 to 1,048 parts per million, an amount from 4 to 7 times that in city sewage. Much gross material passes through visible to the eye, which is not in- eluded in the analysis (table 172). RED SEWER OUTLET. The samples collected from the red sewer at two different times contained from 844 to 1,224 parts per million suspended matter. This sewer is 30 in. diameter, carrying a flow probably as great as that in the grease sewer and should cer- tainly be settled. This sewer, connected with the paunch manure outlet, at times received much material in suspension (table 170). 298 TABLE 170. ANALYSIS OF RED SEWER. Parts pee Million. Determination. May 12, May 13, 1:10 p.m. 10:30 a.m. Suspended Matter: Total 1224 844 Volatile 1120 760 Fixed '.. 104 84 Oxygen Consumed: Total 335 293 Dissolved 182 150 Suspended 153 143 Chlorine 784 650 COMPARISON, OF INFLUENT AND EFFLUENT OP CATCH BASIN. Average samples, collected during one hour on two occa- sions, show little or no improvement in the catch hasin as shown below. TEST. 11 TO 12 A. M. MAY 12. TOTAL FLOW 2.88 CUBIC FEET PER SEC. NOMINAL PERIOD 14 MINUTES. Result in Parts per Million. Determination. Reduction, Influent. Effluent. Per Cent. Suspended Matter: Total 632 696 Increase Volatile 592 656 Fixed 40 40 Oxygen Consumed: ~ Total 310 361 Increase Dissolved 216 214 1 Suspended 94 137 Increase CMorine 1580 1610 " TEST. 11 TO 12 A. M. MAY 13. TOTAL FLOW 2.53 CUBIC FEET PER SEC. NOMINAL PERIOD 16 MINUTES. Parts per Million. Determination. Reduction, Influent. Effluent. Per Cent. Suspended Matter: Total 844 780 8 Volatile 784 732 7 Fixed 60 48 20 Oxygen Consumed: Total 363 372 Increase Dissolved 274 272 1 Suspended 89 100 Increase CMorine 2166 2016 7 PERIOD OF PLOW. The period of flow is shown approximately by the amounts passing over the inlet weir. 299 TABLE 171. HYDRAULIC ELEMENTS OF CATCH BASIN. Calculated Calculated Calculated Flow, Time in Basin, Average Velocity, Maximum Velocity, Cu. Ft. per Sec. Min. Ft. per Mm. Ft. per Min. 0.5 77 1.3 7.5 1.0 39 2.6 15. 1.5 26 3.8 22.5 2.0 20 5.0 30. 2.5 16 6.2 37.5 3.0 14 7.4 45. 3.5 12 8.5 52.5 4.0 10 9.7 60. The calculated maximum velocity is figured on the velocity un- derneath a scum board, with the bottom edge raised 6 in. off the bottom (table 171). These high velocities explain why the deposits wash through and out. The actual period of flow was tested by dye on May 16th. The color was strong at the outlet after 6% min. The actual period of flow is usually less than the calculated period, because of the diffi- culty of obtaining complete displacement. The calculated periods in the catch basin average from 12 to 16 minutes, and are too short for proper settling, particularly with the high velocities. TABLE 172. SULZBERGER SONS CO. Tests on May 12 and 13, 1911. Outlet Weie. Inlet Weik. May. Time of Sampling. Flow, Cu. Ft. per Sec. Suspended Matter. Parts per Million. Flow, Cu. Ft. per Sec. 12 13 10 to 11 a. m. 1.36 808 2.64 11 to 12 Noon 1.52 696 2.88 12 to 1p.m. 1.52 692 2.48 1 to 2 p. m. 2.32 668 2.64 2 to 4 p.m. 2.48 716 3.04 4 to 6 p. m. 1.95 664 Submerged 6 to 8 p.m. 2.61 888 3.32 8 to 9 a.m. 1.32 772 2.46 9 to 10 a. m. 1.49 924 2.67 10 to 11 a. m. 1.92 884 2.51 11 to 12 Noon 2.07 780 2.53 12 to 1p.m. 1.70 776 2.25 1 to 2 p. m. 2.21 712 2.81 2 to 4 p.m. 2.03 1048 2.53 300 CATCH BASIN SLUDGE. A sample of the deposit col- lected from the catch basin on May; 13, at 10 a. m., had a black color with a putrid odor. The analysis shows a liquid sludge, very high in volatile matter, containing some organic nitrogen and fat, much higher than in typical sludge from city sewage. SLUDGE ANALYSIS. Color : Black. Odor: Putrid. Specific Gravity: 1.03. Moisture : 83.2 per cent. Calculated to dry weight : Percent. Volatile matter 87.5 Fixed matter 12.5 Nitrogen ; 3.6 Fat 5.7 SETTLING EXPERIMENTS. Experiments on settling the ef- fluent in a 500 c. c. cylinder show that from 22 to 49. per cent, of the effluent of the present catch basin settles out in 1 hour, under quies- cent conditions, and that 60 per cent, of the effluent of the "red" sewer settles out in 1 hour under quiescent conditions (table 173). Second Test. June 29 to July 1, 1911. FIELD WORK. The second test was made from 8 a. m., June 29, to 8 a. m., July 1, with two weirs, one on the outlet baffle of the catch basin, bei^g weir "A" of the previous test, and one ia the last manhole on the "Red" sewer line. As the condensing water pump in the catch bagin was not run during the test, no influent weir was necessary. The weir in the "Red" sewer was made 20 in. wide with two end contractions, the crest being 13^-in. above the sewer invert (table 174). GREASE SKIMMING TANKS. On the grease sewer, back of the main catch basin, are nine grease skimming tanks besides the old "general receiving basin." All are timber, 5 ft. wide, with a flow depth of 2 ft. 6 in., baffled with scum boards. The receiving basin is 75 ft long. The grease tanks have lengths, respectively, from the back of the receiving basin of 28I/2 ft., 30 ft., 30 ft., 40 ft., 40 ft., 30 ft., 29 ft., 31 ft., and 30 ft. 1,800 to 2,000 men are employed at the plant. All human sewage enters the "Red" sewer. 301 TABLE 173. SULZBERGER SONS CO. Settling Experiments in 500 o. c. Cylinders. Parts pee Million. Sample. ' AI. All. AIII. RI. ORIGINAL— Suspended Matter: Total 696 952 692 860 Volatile 636 856 628 776 Fixed 60 96 64 84 Oxyeen Consumed: -rStal 363 359 266 345 Dissolved : 277 276 183 158 Suspended 86 83 83 187 SETTLED LIQUID— Suspended Matter: Total 412 482 542 352 VolatUe 380 438 482 320 Fixed 32 44 60 32 Oxygen Consumed: ' Total 351 347 261 258 Dissolved...' 277 276 , 183 158 Suspended 74 71 78 100 PERCENTAGE REDUCTION BY 1 HOUR QUIESCENT SETTLING— Suspended Matter: ^^ ^^ ^^ ^^ voMie;::::;:;:::::::::::.... i^ tl 'l H Fixed 47 54 6 62 °S.':°.'!'.''"'^.:...; 3.3 3.4 1.9 25 Dissolved ■■ ••• •■■ •■• Suspended 14 15 6 47 Note. Composite samples are made up as follows: AI. From samples collected between 10 a. m. and 8 p. m. May 12, Outlet of Catch Basin. All. From samples collected between 8 a. m. and 4 p. m. May 13, Outlet of Catch Basin. AIII. Sample collected between 12 and 1 p. m. May 12, outlet of catch basin. RI. From samples collected from "Red" sewer May 12 and 13. 302 05 o OS o tsa I-:) t CO 5 "S o ^ ° § CO u OS DQ >> +3 'i ^f 1 <1 g v'B S o W ^^ fl cS a S g- 3 03 3, . !" 1^ E-r u •sg T)-43 o a ■H 03 Fh I — 1 -3 i C3 gooo ^5 §gs;§ U3O00U3 rHTH1-l(^5 S5 (M 00 t-H TP Qooo eococ OoOO « (^ I* . P^ ^ *3 4 d a, '3 V o s g ^ o o g ■ rH 0) s og . "^ -g ft ^ s i o O 03 5 3 P4 rt 03 i O o H (U .a (4 fH s -t-3 -1-3 cd § •u 1 T3 [o K" g- s CQ • . \. o3 a 1^ i-H ph**: w •^g -d'-C o S • A (U t4 ■ — ^"3 s. oa ooooooooo COOSCpOiOCOCOCO.-i CDCOeDirH00TteO^ i^ «t^CQCO00-» ■* d (N (M O (N -OpT)! OCOi-llNC^ICO ■■*00 00 T-l 00 »-< 05 CO -tHt^ t000O(NTHtt>(MT)<(O COOi'^'Odt^rttDOi 0SrH05rHOCC00»-l05 >ON00>-l00T-IO5Tl •^ 49 n ■a O =3 -^ d • ^ m u o 0] ^^ fl OS ^ i d i V <1 e o a += .^ g- 3 CQ -s E-1 d |P Psi '^^ u «« e O c Tj'^ *E ^ ^6 6 ■*s ce P ooooooooo T-Jtg(N!OC5lOogi-<«3 COCO-^OOCO-^OCOflO THOOCiOaSCDlO'^t^CO cqoooioto-* ■ -(M 1— 1 1> O T-( iO CO ■ -co O *-l 1-H (M C7S l>0000CsOsO 310 about 70 per cent, of the total suspended matter settled out in 1 hour. "C." PACKERS AVENUE TO THE RIVER. This is an old 12-in. box sewer, taking the flow from the hair factory, overflow from the reservoir and Lib by 's pickle house. A weir without end contractions, with crest 12%-in. long, was built in a manhole near the switch tracks at the north end of Packers avenue. The height of the weir above the sewer invert was 10 in. Samples and readings were taken once an hour from 8 a. m. to 4 p. m., no samples being collected at night (table 177). "D." 41ST ST. TO CENTER AVENUE. This is a 24-in. tile sewer on the south side of 41st street, re- ceiving the drainage from part of the hog house (mostly condensing and scald water, wash and pickle water), refrigerator plant, engine room, warehouses, general office and some of the Libby toilets. Read- ings were taken over a 24-in. weir with two end contractions, built in the last manhole before the line joins the Morris hog house sewer. Samples and readings were taken once an hour from 8 a. m. to 4 p. m. (table 178). "E." 42D ST. TO CENTER AVENUE. DESCRIPTION. This 24-in. tile sewer receives nearly the en- tire flow from the hog house, including the killing and cutting floors, and the boiler and ice-machine rooms. The flow from the hog house, itself, passes through a concrete catch basin, while that from the boiler and ice-machine rooms is by-passed in a 10 by l^-in. box sewer, joining the main line in a manhole below the catch basin, CATCH BASIN. The hog house catch basin is built of concrete, 90 ft. long by 7 ft. wide, with a flow depth of about 3 ft. 9 in. There are 5 concrete underflow baffles, 15 ft. apart, each having a flow space 12 in. deep. Alternating with these are concrete overflow baffles, rising to 6 in. below the normal water surface. At the effluent end are 3 sets of l^^-in. mesh wire screens, sliding in guides, but pad- locked. One man skims off the grease, and removes the sludge with a shovel. The sludge is almost entirely paunch manure, and small trimmings, fairly fresh in appearance. WEIR AND SAMPLES. A 24-in. weir with two end contrac- tions was built in the manhole at the junction of the two sewers. Samples were taken once an hour from 8 a. m. to 4 p. m. daily. No samples were taken at night (table 179). SETTLING EXPERIMENTS. In settling experiments made on 311 o o I pi 111 <>< 00 < P3 t o O GO o I >, I ■*^ •- ( . 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In general, the "Standard Methods of Analysis" (second edition) recommended by the American Public Health Asso- ciation, were followed, except as indicated herein. ORGANIC NITROGEN. The sample was digested with concen- trated sulphuric acid, diluted with water, neutralized with sodium hydrate, and made up to a definite volume. After standing over night, an aliquot portion was Nesslerized. The free ammonia, de- termined separately, was subtracted to give the organic nitrogen. The nitrogen in sludge was determined in substantially the same manner. FREE AMMONIA. Free ammonia was determined by dis- tillation and subsequent Nesslerization. NITRATES. Nitrates were determined by the aluminum reduc- tion method. OXYGEN CONSUMED. The oxygen consumed was deter- mined by digesting the acidified sample with standard potassium permanganate solution in the steam bath for 30 mioutes, and retitra- tion with standard oxalic acid. SUSPENDED MATTER. Suspended matter was determined by the Gooch crucible method. A known volume of the liquid was filtered through a thin mat of finely divided asbestos fibre, depos- ited in the bottom of a perforated porcelain crucible. The increase in weight after drying was noted. ' FATS. The fat content of sewage and effluents was deter- mined by evaporating the acidified sample to dryness, and extract- ing the fat with ether. In determining the fat in sludges, acidifica- tion was omitted in most cases, the ether extraction being made directly on the dried residue. In special cases noted, the sludge was acidified. BIOLOGIC OXYGEN CONSUMPTION. (BIO-CHEMICAL OXYGEN DEMAND.) The saltpetef method used was developed by Dr. Arthur Lederer, and' is described in detail in the Journal of Infectious Diseases, May, 1914. The method, in brief, consists in the addition of definite amounts of saltpeter (sodium nitrate c. p.) to the sample, incubation with the addition of metheylene blue as an indicator for 10 days at 20 deg. C, and the determination of the residual nitrite-nitrate. From an extended series of tests, it has 319 been found that 2 molecules of the nitrate yield approximately 5 atoms of available oxygen. Knowing the difference between the amount of nitrate added to the sample and that remaining after incubation, the oxygen demand can be readily calculated. "Where necessary (as in sprinkling filter effluents), the total available oxygen in the original sample is also determined and a correction made in the calculation. SPECIFIC GRAVITY. The specific gravity of sludges was determined by filling a flask of known capacity and weighing. "Where necessary to fill voids in the mass, water was added in known amount, and correction made in computing the results. PER CENT. MOISTURE. The moisture content of sludges and screenings was obtained by noting the loss of weight after dry- ing over the steam bath. METHOD OF SAMPLING. In all routinei sampling, com- posites were made of 125 c. c. portions taken every hour. For spe- cial tests the procedure was changed to meet conditions. Owing to the wide variation in strength of the day and night sewage, two separate samples covering the heavy day and the weak night sewage were analyzed. The following table indicates the sampling schedule followed for the crude sewage : SAMPLING SCHEDULE— CRUDE SEWAGE. Date Day Sewage NiOHT Sewage From To First Sample Last Sample First Last Sample Sample Remarks Oct. 1, 1912 Jan. 1, 1913 Jan, 1, 1913 Feb. 1, 1913 Feb. 1, 1913 Jan. 1, 1914 Jan. 1. 1914 Date 8 a. m. 7 p. m. 8 p. m. 7, a. m. 7 a.m. 10 p.m. 11p.m. 6 a.m. 8 a. m. 10 p. m. 11 p. m. 7 a. m. No samples — grit chamber effluent only. Daily DaUy Bi-Daily Weighted averages to cover the 24 hr. were also made. Up to January 1, 1913, one composite covering the entire 24 hr. was taken for the grit chamber and tank effluents. Thereafter, "day" and "night" samples were taken for all devices, allowance being made in the tank samples for the nominal detention period in each case. After January 1, 1914, no samples of crude sewage were taken, as the grit chamber effluent was practically identical in com- position. Daily samples of the various effluents were taken up to February 1, 1913, and after that bi-daily composites were made. Sunday samples were, however, kept separate and were omitted after January 1, 1914. 320 The method of taking samples for the biologic oxygen consump- tion tests is outlined in Chap. XV. Samples of sludge and scum for analyses were taken from the tanks, either when cleaned, or at stated intervals when cleaning was infrequent. Sludge samples were collected by lowering into the sludge mass a bottle attached to a stick and plugged by a stopper.. The stopper was then withdrawn by a cord, allowing the sludge to flow in without catching any of the supernatent liquor. A number of samples at various depths were always taken to insure repre- sentative composites. METHOD OP SLUDGE AND SCUM MEASUREMENT. Sludge was measured in situ in the tanks by the method devised by Mr. H. B. Hommon at Gloversville, N.-Y. A wide-mouthed bottle, with stopper in place, was attached to a calibrated rod and lowered into the tank to a definite depth. The stopper was withdrawn allowing the bottle to fill. The bottle was then lifted and examined. This operation was repeated until the sludge line was closely located. This method was not wholly satisfactory, as it partly ig- nores the consistency of the sludge other than is visual. In cleaning the Dortmund tanks where the sludge was not entirely drawn out, the amount removed as calculated from the difference between meas- urements before and after cleaning was much smaller than would be supposed, due to the stirring and thinning of the sludge in the process of withdrawal. The residual sludge doubtless compacted again slowly after cleaning was completed, but the net result indi- cated a smaller accumulation of sludge than was actually secured. This tendency was more marked for tanks frequently cleaned and probably accounts largely for~the lower average sludge accumula- tion noted for tank C, the true rate probably being somewhat higher. In the spring of 1914, samples of sludge were taken from the tanks both before and after cleaning, so that variations in moisture content could be traced and correction made. Scums were ordinarily measured by running onto a sludge bed and noting the depth, or if small in amount, a calibrated can or barrel was used. LIST OF TABLES. DIAGRAMS, AND PLATES AND TOPICAL INDEX 323 LIST OF TABLES, DIAGRAMS AND PLATES. TABLES. Table. Description. i Page 1 Analyses of Sewage from Stockyards and Packingtown Sewers. Prof. H. J. Long, 1890 ' 6 2 Head of Cattle, Sheep, Calves and Hogs Used in City Yearly since 1866 9 3 Preliminary Analyses of Wastes from Individual Houses . 12, 13 4 Synopsis of Operations in Individual Houses face 22 5 Record of Killing of Hogs in Individual Houses from 1906 21 6 Summary of Flows, and Suspended Matter Discharged from Individual Houses, 1911 23 7 Reduction of Suspended Matter, Experimental Settling Basin, Morgan St. Sewer, 1911 28 8 Analyses of Sludge, Experimental Settling Basin, Mor- gan St. Sewer, 1911. 30 9 Crude Sewage, Center Ave. Testing Station, Monthly Average Analyses (Day, Night and 24-Hr.) .42, 43 10 Crude Sewage, Monthly Average Analyses (Day) Com- pared with Monthly Averages at 39th St.. ..... .... . 44 11 Analyses of Sewage from Various American Cities 41 12 Crude Sewage, Ho,urly Variations in Suspended. Matter. 45 13 Crude Sewage, Monthly Averages on Sundays (Day and 24--Hr.) 46 14 Crude Sewage, Total Solids .^. . . 48 15 Crude Sewage, Ether Soluble Matter 49 16 Crude Sewage, Comparative Analyses of Center and Ash- land Aves 52 17 Grit Chamber," Sludge Accumulation and Analyses 53 18 Grit Chamber, Reduction of Suspended Matter (Day, Night and 24-Hr.) ,. . ., 55 19 Grit Chamber, Special Ana,lyses for Suspended Matter and Chlorine 56 '20 Grit Chamber, Scum Accumulation 56 21 Grit Chamber, Scum Analyses 57 22 Dortmund Tank C, Operating Schedule 58 23 Dortmund Tank D, Operating Schedule 59 324 Table. Description. Page 24 Dortmund Tanks C and D, Monthly Average Analyses of Effluent (Day) 60 25 Dortmund Tank C, Reduction in Suspended Matter (Day, Night and 24-Hr.) 61 26 Dortmund Tank D, Reduction in Suspended Matter (Day, Night and 24-Hr.) 62 27 Dortmund Tanks C and D, Reduction of Suspended Matter by Velocities and Flow Periods 63 28 Dortmund Tank C, Reduction in Suspended Matter after Fine Screening, May, 1914. . .' 64 29 Dortmund Tank C, Reduction in Suspended Matter after Fine Screening, July, 1914 65 30 Dortmund Tanks C and D, Reduction in Organic Nitrogen, Free Ammonia and Oxygen Consumed 67 31 Dortmund Tank: D, Sludge and Scum Accumulation. ... 68 32 Dortmund Tank C, Sludge and Scum Accumulation .... 69 33 Dortmund Tanks C and D, Sludge Accumulation by Velocities and Flow Periods 70 34 Dortmund Tank C, Sludge and Scum Accumulation, Based on Uniform Moisture Content 71 35 Dortmund Tank D, Sludge and Scum Analyses 72 36 Dortmund Tank C, Sludge and Scum Analyses 73 37 Emseher Tank E, Operating Schedule 76 38 Ejnscher Tank E, Monthly Average Analyses of Effluent (Day) 77 39 Emseher Tank E, Reduction of Suspended Matter (Day) . 78 40 Emseher Tank E, Reduction of Suspended Matter (Night) 79 41 Emseher Tank B, Reduction of Suspended Matter (24-Hr.) 80 42 Emseher Tank E, Reduction of Suspended Matter by Ve- locities and Flow Periods 81 43 Emseher Tank E, Reduction in Organic Nitrogen, Free Ammonia, and Oxygen Consumed 82 44 Emseher Tank E, Accumulation of Sludge and Scum .... 84 45 Emseher Tank E, Accumulation of Sludge and Scum by Velocities and Plow Periods 85 46 Emseher Tank E, Accumulation of Sludge and Scum based on Uniform Moisture 86 47 Emseher Tank E, Analyses of Bottom Sludge 87 48 Emseher Tank E, Analyses of Scum from Gas Vent 88 49 Emseher Tank E, Analyses of Scum from Settling Chamber 89 325 Table. Description. Page 50 Chemical Precipitation, Seduction in Suspended Matter, Laboratory Experiments 94 51 Chemical Precipitation, Reduction in Suspended Matter, Laboratory Experiments 95 52 Chemical Precipitation, Analyses of Lime 96 53 Chemical Preeipitatioit. Results of Preliminary Operation 98 54 Chemical Precipitation, Operating Data by Runs 99 55 Chemical Precipitation, Removal of Suspended Matter by Runs (Day and 24-Hr.) 101 56 Chemical Precipitation, Reduction in Organic Nitrogen, Free Ammonia, and Oxygen Consumed 103 57 Chemical Precipitation, Reduction of Soluble Constituents. 104 58 Chemical Precipitation, Sludge Accumulation by Runs . . 105 • 59 Chemical Precipitation, Sludge Analyses 106 60 Sludge Drying, Variations in Moisture Content of Sludge and Scum Ill 61 Sludge Drying Records, Sludge and Scum, Dortmund Tank C 112 62 Sludge Drying Records, Sludge and Scum, Dortmund Tank D 113 63 Sludge Drying Records, Sludge and Scum, Bmscher Tank E 114 64 Sludge Drying Records, Chemical Precipitation Sludge . . 115 65 Sludge Drying, History of Sludge Beds 119 66 Sludge Drying, Analyses of Effluent from Underdrains . . 120 67 Sludge Drying; Reduction in Nitrogen, Pat, and Volatile Matter on Long Drying Sludge 121 68 Sludge Drying, Reduction in Nitrogen, Pat, and Volatile Matter on Long Drying Scums 122 69 Sludge Pressing, Record of Results 126 70 Sludge Pressing, Analyses of Piltrate 127 71 Analyses of Sludge for Fertilizer Constituents 129 72 Analyses of Sludges Used in B. T. U. Determinations 130 73 Analyses of Sludges for B. T. U 131 74 Coarse Screening, Removal of Material by Monthly Aver- ages .' ^^^ 75 Coarse Screening, Analyses of Screenings 134 76 Rotary Screen, Removal of Suspended Matter on First Run 136 77 Rotary Screen, Analyses of Screenings 138 78 Rotary Screen, Accumulation of Screenings, First Run. . 139 326 Table. Description. Page 79 Rotary Screen, Accumulation of Screenings, Second Run. 140 80 Rotary Screen, Accumulation of Screenings, Third Run. . 142 81 Removal of Suspended Matte;- by Jennings Screen and Weand Screen at Sulzberger's 145 82 Accumulation of Screenings, by Jennings Screen and Weand Screen, at Sulzberger 's 146 83 J^ine Screening Experiments, Mechanical Properties of Screens 150 84 Fine Screening Experiments, Reduction of Suspended Matter by Different Mesh Screens 152 85 Fine Screening Experiments, Reduction of Suspended Matter by Different Mesh Screens (Computed) .... 154 86 Fine Screening Experiments, Accumulation of Screenings for Different Mesh Screens 15^ 87 Fine Screening Experiments, Comparative Accumulation of Screenings, 39th St. and Center Ave 158 88 Fine Screening Experiments, Analyses of Screenings . . . 158 89 Fine Screening Experiments, Mechanical Properties of Slotted Plates 159 90 Fine Screening Experiments, Time of Clogging with Slotted Plates 159 91 Pine Screening Experiments, Reduction of Suspended Matter with Slotted Plates 160 92 Fine Screening Experiments, Accumulation of Screenings with Slotted Plates 161 98 Comparative Removal of Suspended Matter by Various Preliminary Devices 164 94 Monthly Average Temperatures, Crude Sewage, Tank and Filter Effluents . . 168 95 Reduction of Suspended Matter by Quiescent Settling 171 96 Sprinkling Filter, Operation Schedule 174 97 Sprinkling Filter, Monthly Average Analyses of Effluent (Day, Night and 24-Hr.) 175 98 Sprinkling Filter, Monthly Average Reduction of Sus- pended Matter (Day, Night and 24-Hr.) 176 99 Sprinkling Filter, Percentage of Putrescible Effluent Samples by Months 178 100 Sprinkling Filter, Relative Stability of Effluent by Months 179 101 Sprinkling Filter, Dissolved Oxygen in Effluent by Months 179 327 Table. Description. Page 102 Secondary Settling Basin, Monthly Average Eemoval of Suspended Matter (Day, Night and 24:-Hr.) 182 103 Secondary Settling Basin, Percentage of Putrescible Effluent Samples by Months 184 103a Secondary Settling Basin, Relative Stability of Effluent by Months ... 1S3 104 Secondary Settling Basin, Dissolved Oxygen in Effluent by Months 184 105 Secondary Settling Basin, Sludge and Scum Accumulation 185 106 Secondary Settling Basin, Sludge Analyses 186 107 Fat Removal by Different Tanks 188 108 Pat Removal in Emscher Tank and Sprinkling Filter 189 109 Reduction in Various Constituents by Treatment with Acid, Tank C 192 . 110 Oxygen Demand, Crude Sewage by Months 195 111 Monthly Average Reduction in Oxygen Demand by Sedi- mentation 196 112 Reduction in Oxygen Demand by Fine Screening 197 113 Monthly Average Reduction in Oxygen Demand by Sprinkling Filter . . . , 199 114 Data on City Sewers Discharging into East and West Arms , 201 115 Data on Private Sewers Discharging into East and "West Arms , 202 116 Analyses of Sewage from Sewers Discharging into East and West Arms 203 117 Discharge of Center Ave. Sewer, 1911 206 118 Discharge of Center Ave. Sewer, 1912-13 207 119 Discharge of Ashland Ave. Sewer, 1911 208 120 Discharge of Robey St. Sewer, 1911 209 121 Discharge of Robey St. Sewer, 1913 210 122 Comparative Discharge from Center and Ashland Ave. Sewers and Individual Houses, 1911 210 123 Daily Precipitation Record, Testing Station Rain Gage. . 211 124 Adler & Oberndorf , Analyses and Plow of Sewage 226 125 Anglo-American Provision Co., Analyses of Sewage 229 126 Anglo-American Provision Co., Elements of Catch-Basin. . 230 127 Anglo-American Provision Co., Comparison of Influent and Effluent of Catch-Basin 230 128 Armour & Co., Analyses and Plow of Sewage, 43rd St. Sewer '. . . . 234 328 Table. Description. Page 129 Armour & Co., Analyses and Flow of Sewage, 43rd Place Sewer 236 130 Armour & Co., Elements of 43rd Place Catcli-Basin 235 131 Armour & Co., Analyses and Flow of Sewage, 44th St. Sewer 238 132 Armour & Co., Analyses of Sewage from Glue "Works. . 240 133 Boyd-Lunham Co., Analyses and Flow of Sewage 243 134 Boyd-Lunham Co., Elements of Catch-Basin 244 135 Brennan Packing Co., Elements of Catch-Basin 245 136 Brennan Packing Co., Analyses and Flow of Sewage 246 137 Chicago Packing Co., Elements of Catch-Basin 247 138 Chicago Packing Co., Analyses and Flow of Sewage 248 139 Darling Fertilizer Co., Analyses and Flow of Sewage from Glue Works .251 140 Friedman M'f 'g. Co., Elements of Catch-Basin 252 141 Friedman M'f 'g. Co., Analyses and Flow of Sewage 253 142 Henry Guth, Analyses and Flow of Sewage 255 143 G. H. Hammond Co., Suspended Matter and Flow of Sewage 262 144 G. H. Hammond Co., Elements of Catch-Basin 260 145 G. H. Hammond Co., Analyses of Sludge from Catch- Basin 261 146 G. H. Hammond Co., Laboratory Settling Experiments on Sewage 264, 265 147 Independent Packing Co., Elements of Catch-Basin 266 148 Independent Packing Co., Analyses and Flow of Sewage . . 267 149 Libby, McNeill & Libby, Elements of Catch-Basin 269 150 Lifcby, McNeill & Libby, Flow of Sewage 269 151 Libby, McNeill & Libby, Analyses and Flow of Sewage. . 270 152 Miller & Hart, Elements of Catch-Basin 272 153 Miller & Hart, Analyses and Flow of Sewage 273 154 Morris & Co., Elements of Catch-Basin, Beef Division 277 155 Morris & Co., Flow of Sewage, Beef Division 278 156 Morris & Co., Analyses and Flow of Sewage, 42nd St. Sewer, Beef Division 279 157 Morris & Co., Analyses and Flow of Sewage, 44th St. Sewer, Beef Division 280 158 Morris & Co., Elements of Catch-Basin, Hog House 282 159 Morris & Co., Flow of Sewage, Hog House 282 160 Morris & Co., Analyses and Flow of Sewage, Hog House. . 283 329 Table. Description. Page 161 Morris & Co., Reduction of Suspended Matter in Settling Basin, Hog House 284 162 Northwestern Glue Co., Elements of Catch-Basin 285 163 Northwestern Glue Co., Analyses and Flow of Sewage . . 286 164 Peoples Packing Co., Analyses and Flow of Sewage 288 165 Louis Pfaelzer & Sons, Elements of Catch-Basin 289 166 Louis Pfaelzer & Sons, Analyses and Flow of Sewage 290 167 Siegel-Heehinger, Elements of Catch-Basin 292 168 Siegel Hechinger, Analyses and Flow of Sewage 293 169 Standard Slaughtering Co., Analyses and Flow of Sewage 295 170 Sulzberger & Sons Co., Analyses of Sewage from Red Sewer 298 171 Sulzberger & Sons Co., Elements of Catch-Basin 299 172 Sulzberger & Sons Co., Analyses and Flow of Sewage.,. ; . 299 173 Sulzberger & Sons Co., Laboratory Settling Experiments on Sewage 301 174 Sulzberger & Sons Co., Analyses and Flow of Sewage, Second Test 302 175 Swift & Co., Analyses and Flow of Sewage, 40th St. Sewer 306 176 Swift & Co., Analyses and Flow of Sewage, 42nd St. Sewer 309 177 Swift & Co., Analyses and Flow of Sewage, Packers' Ave. Sewer 311 178 Swift & Co., Analyses and Flow of Sewage, 41st St. Sewer 312 179 Swift & Co., Analyses and Flow of Sewage, Miscellaneous Outlets 313 180 "Western Packing Co., Elements of Catch-Basin 316 181 Western Packing Co., Analyses and Flow of Sewage 317 DIAGRAMS. Figure. 1 Total Head of Animals Slaughtered in Chicago and Popu- lation 8 2 Seasonal Distribution of Slaughtering 10 3 Map Showing Sewers in Stockyards and Packingtown. . face 20 4 Details of Present and Proposed Catch-Basins in Stock- yards 26 5 Plan of Center Ave. Testing Station face 32 6 Profile of Center Ave. Testing Station face 32 7 Details of Dortmund Tanks 34 330 Figure. Description. Page 8 Details of Bmscher Tank face 34 9 Details of Eotary Screen 36 10 Daily Temperature of Crude Sewage, 39tli St. and Center • Ave., and of Air 50 11 Monthly Average Temperature, Air, Lake Water and Crude Sewage at 39th St. and Center Ave 51 12 Distribution of Flow, Dortmund Tank C 74 13 Digestion of Sludge in Emscher Tank 91 14 Details of Loss of Head Apparatus 149 15 Times of Clogging with Screens of Different Mesh 151 16 Kemoval of Dry Material by Screens of Different Mesh . . . 157 17 Eemoval of Suspended Matter in Crude Sewage by Quiescent Settling 172 18 Map of Sewers Tributary to East and West Arms .... face 200 19 Hourly Variations in. Suspended Matter, Center Ave. Sewage . . . : 204 20 Hourly Variations in Flow, Center Ave. Sewer, June, 1913 205 PLATES. Plate. 1 Center Ave. Testing Station from North 31 2 Center Ave. Testing Station from South 31 3 East Arm of South Fork of South Branch of Chicago River from. Racine Ave. Bridge Looking East 32 331 TOPICAL INDEX . ■ , Page Acid treatment, see Fats. Acknowledgments 27 Adler and Oberndorf , test 225, 226 Alkalinity, sewage, Center Ave 48 Analyses, chemical precipitation, chemicals used 96, 97 Crude sewage, American cities 41, 45 Ashland Ave 52 Center Ave 40-44 ' Emptying into Bubbly Creek 200, 203, 204 Individual packing houses 22, 24 Long, Prof. J. H 3, 4, 6 Morgan St 27, 144 39th St 41, 42 Sulzberger Sons Co 144 Effluent, acid treatment of sewage 192 Chemical precipitation 100, 101, 103 Dortmund tanks 59, 60 Emscher tank 76, 77 Sludge press 127 -Sprinkling filter 174, 175 Underdrainage from sludge beds 119, 120 Scum, Dortmund tanks 72-74 Emscher tank 88-90 Grit chamber 57 Screenings, coat-se screen 134 Jennings screen 147 Loss of he^d tests 15lS, 159 Rotary screen 138 Weand screen, Sulzberger's 147 Sludge, acid treatment 193, 194 Air drying 120-123 Calorific value 130, 131 Chemical precipitation 106, 107 Dortmund tanks 72-74 Emscher tank 87-90 332 Page Analyses, Sludge, fertilizing value 128, 129 Filter Press 128 Grit chamber 53, 54 Secondary settling basin , 186 Analytical methods 195, 318, 319 Anglo- American Provision Co., test 227-231 Armour and Co., glue works, test 239-241 Packinghouse, test 232-238 Ashland Ave. sewer, analyses 52 Gagings 206, 208 Biologic Oxygen Consumption, acid treatment, reduction by. . . 193 Method of determination 195 Method of sampling 196 Screen, rotary, reduction by 197, 198 Settling tanks, . reduction by 196-198 Sewage, crude. Center Ave 195-197 39th St 195, 197 Sprinkling filter, reduction by 198, 199 Board of Health, City of Chicago 4 Boston, Mass 191 Boyd-Lunham Co., test 242-244 Bradford, Eng 190-191 Bubbly Creek, see Chicago River, also Projects. Brennan Packing Co., test 245 Calorific value, screenings, scum and sludge 129-132 Cassel, Germany 191 Center Ave. sewer, analyses 40-44 Gagings 204-207 Chemical Precipitation, appearance of effluent 102 Biologic oxygen consumption, reduction by 196-198 Chemicals, analyses of 96, 97 Application of 96, 97, 99, 100 Cost of 107, 108 Theoretical requirements 108, 109 Cleaning of tank 107 Deiscription of apparatus 39, 93, 96 333 Page Chemical Precipitation, effluent, analyses 100, 101, 103 Fat, removal by 187-189 Free ammonia, reduction of 102, 103 Laboratory experiments 93-95 Operation data, individual runs 99, 100 Organic nitrogen, reduction of 102, 103 Oxygen consumed, reduction of 102, 103 Preliminary experiments 97, 98 Scum, formation of 104, 106 Sludge, accumulation of 102, 104, 105 Analyses of 106, 107 Disposal, see Sludge. Soluble constituents, reduction of 102, 104 Suspended matter, reduction of 100, 101 Chicago Packing Co., test ,247-249 Chicago River, South Fork of South Branch, see also Projects. Dredging 2, 3 Flushing .2 Sanitary condition 2-5 West 39th St. conduit 208, 209 Chlorine, Ashland Ave. sewage 52 Center Ave. sewage • . . : 47 Conclusions, regarding sewerage and treatment 221 Controlling Apparatus, Center Ave. testing station 33 Cooley, Lyman E 3 Cost, acid treatment 194 Chemical precipitation, chemicals 107, 108 Projects, sewerage 218-220 Treatment 220-222 Darling Glue Plant, test 250, 251 Digestion, Bmseher tank sludge 90-92 Dissolved Oxygen, secondary settling basin effluent 181, 182, 184 Sprinkling filter effluent ■ 1'''9 Dortmund Tanks, biologic oxygen consumption, reduction of. .196-198 Cleaning of "^0, 72, 73 Description of 33-35, 58 334 Page Dortmund Tanks, effluent analyses 59, 60 Pat, removal by 187-189 Plow period in, actual 74 Nominal 58, 59, 62-64, 70 Pree ammonia, reduction of 66 Gas production 70, 72 Odor 72 Operation of 58, 59 Organic nitrogen, reduction of 66 Oxygen consumed, reduction of ' 66 Scum, accumulation of 66-72 Analyses of 72-74 Disposal, see Sludge. Presence of 66, 70 , Prevention by fine screening 66 Sludge, accumulation of 67-72 Analyses of 72-74 Appearance of 72 Disposal, see Sludge. Suspended matter, reduction of 61-65 Vertical velocities 58, 59,62-64, 70 Emscher Tank, biologic oxygen consumption, reduction of ... . 196-198 Description of 35, 37 Effluent, analyses ' 76, 77 Fat, removal by 187-189 Plow period 76, 81, 82 Pree ammonia, reduction of 82, 83 Gas production in 83, 84 Odor 83 Operation of 76 Organic nitrogen, reduction of 82, 83 Oxygen consumed, reduction of 82, 83 Ripening of 83, 84, 92 Scum, accumulation of 83-86 Analyses of 88-90 Disposal, see Sludge. 335 Bmscher Tank, Sludge, accumulation of .84-87 Analyses of 87-90 Appearance of 90 Digestion of 90-92 Disposal, see Sludge. Suspended matter, reduction of 78-82 Velocities in 76, 81, 82 Fats, Acid Treatment, analyses of sludge 193, 194 Cost of 194 Conclusions 194 Method of investigation 191, 192 Results of 193, 194 Animal fat, composition of 187 Grit chamber, removal by 57, 187, 189 Melting point of 187 Recovery of, various cities 190, 191 Screens, clogging by 148 Sedimentation tanks, removal by 187-189 ' Sewage, Center Ave .48, 49, 187 Sludges, amount in • 190 Sprinkling filter, removal by .' 189, 190 Fertilizer, sludge, value of 128, 129 Filter, see Sprinkling Filter. Firms in Stockyards and Packingtown 233, 234 Flies, drying sludge on beds, breeding in , 120 Scum on tanks, breeding in 66 Sprinkling filter, appearance about 180 Flow, sewage, see Sewers. Frankfort, Germany 1^1 Free ammonia, chemical precipitation, reduction of. 102, 103 Crude sewage. Center Ave 47 Dortmund tanks, reduction of 66 Bmscher tank, reduction of 82, 83 Friedman Mfg. Co., test 252, 253 Gas production, in Dortmund tanks "70, 72 Emscher tank ^^' ^* Grease, see Fats. 336 « Page Grit Chamber, description of 33 Fats, removal of ' 57, 187, 189 Operation of 53, 54 Period in 54 Scum, accumulation of 56, 57 Analyses of 57 Sludge, accumulation of 53, 54 Analyses of 53, 54 Suspended matter, reduction of 54-56 Velocities in 53, 54 G. H. Hammond Co., test 256-265 Guth, Henry, test 254, 255 Independent Packing Co., test , 266-268 Jennings, C. A., see Screens. Letter of transmittal I-IV Libby, McNeill & Libby, test 269-271 Long, Prof. J. H. . . .: 3, 4, 6 Loss of head experiments, see Screens. Miller & Hart, test 272-274 Morris & Co., test 275-284 Nitrates, crude sewage, Center Ave 47 Nitrification in sprinkling filter 177 Nitrites, crude sewage. Center Ave 47 Northwestern Glue Co., test 285, 286 Odor, chemical precipitation , 106, 168 Coarse screen, screenings from 134 Dortmund tanks 72 Emscher tank 83 Kotary screen, screenings from 138 Scums, comparative 167, 168 Sludges, coniparative 167, 168 Sprinkling filter 180 Sludge beds 118 Tanks, comparative 167, 168 Oldham, England 191 Operation, chemical precipitation, individual runs 99, 100 Dortmund tanks 58, 59 Emscher tank 76 337 Page Operation, grit chamber 53, 54 Influence of velocity and detention period, various tanks. . 165 Jennings screen . , 145, 146 Secondary settling basin 181 Sprinkling filter, nozzle clogging 180 Rotary screen 135 Weand screen at Sulzberger's : . .145, 146 Organic Nitrogen, sewage. Center Ave 47 Chemical precipitation, reduction of 102, 103 Dortmund tanks, reduction of 66 Emscher tank, reduction of 82, 83 Oxygen Consumed, Center Ave. sewage 47 Chemical precipitation, reduction of 102, 103 Dortmund tanks, reduction of 66 Emscher tank, reduction of 82, 83 Method of determination 47 Oxygen Demand, see Biologic Oxygen Consumption. Packing Industry, see also Stockyards, and Stockyards and Paek- ingtown. Ammonia production 17 Button manufacture '. 17 Canning 17 Cattle packing, bone department 16 Butterine manufacture 15 Casing cleaning 15 Fertilizer manufacture 15, 16 Hide curing • 1* Killing V 14 Oil recovery • • 14 Sausage manufacture 16 Tankage 15 Tripe preparation 16 Glue manufacture 17-19 History of • 1' 2 Hog packing, cutting and grading 16 Hair 17 KiUing , 16 338 Page Packing Industry, Hog packing, lard, grease, etc 17 Sausage room 16, 17 Individual houses, classification of 20 Plow, measurement of 22, 206, 208 General recommendations 24, 25 Method of investigation 19, 20, 22 Results of investigation 22, 23, 24 Sampling, method of 22 Pharmaceutical preparations : 17 Processes, sources of information 11, 14 Sheep packing .16 Soap manufacture 17 Peoples Packing Co., test .'' 287, 288 Pfaelzer & Sons, test 289-291 Precipitation, record at Center Ave. testing station 209-211 Projects, filling Bubbly Creek, areas recovered 215 Pill required 215 Improvement of present conditions 214 Object of investigations 212 Policy regarding industrial wastes 212, 213 Recommended scheme, sewerage and treatment 221 Recoveries 213 Sewers, alternative interception schemes 216-219 Cost of interception , 218-220 Packingtown sewers . . .* 217, 218 Proposed new Center Ave. sewer 216 Suggested improvements in region 212, 213 Treatment, alternative schejnes ^ . . . 216, 217 Available methods ; 213, 214 Biological treatment , .221, 222 Cost for various methods 220-222 Screening 220 Screening plus sedimentation 220, 221 Sites and areas required 215, 216 Pumping equipment, Center Ave, testing station 32, 33 Putrescibility, secondary settling basin, effluent 181, 184 339 Page Putrescibility, sprinkling filter effluent 177 Quiescent Settling, results of 169-173 Rainfall, see Precipitation. Rate, screens, Jennings 145, 146 Rotary 135, 137 Weand at Sulzberger's 145, 146 Sprinkling filter 174 Recommendations, sewerage 221 Treatm^ent 221 Relative Stability, secondary settling basin effluent 181, 183 Sprinkling filter effluent 177-179 Eobey St., sewer gagings 206, 209, 210 Sampling, method of, biologic oxygen consumption 196 Individual packing-house tests 22 Testing station, Center Ave 40, 319, 320 Screens, Coarse, description of , 32, 133 Screenings, accumulation of 133, 134 Analyses of 134 Odor 134 Jennings, cleaning of 144, 147, 148 Description of 143, 144 Operation of 145, 146 Rate 145,146 Screenings, accumulation of 146, 147 Analyses of 147 Sewage treated, analyses of 144 Suspended matter, removal of 145, 147 Loss of head experiments, apparatus 148, 149 Comparison of mesh screens and slotted plates 160, 161 Comparison of 39th St. and Center Ave. results 158 Mesh screens, mechanical properties of 148, 150 Method of testing 148, 150 Screenings, accumulation of 155-158, 161, 162 Analyses of 1^8> ^^^ Appearance of ■'■^" Slotted plates, mechanical properties of • 159 340 Page Screens, Loss of head experiments, suspended matter, reduction of , 152-154, 160-162 Time of clogging 150, 151, 153, 159, 160 Eotary, biologic oxygen consumption, reduction of . . . .197, 198 Cleaning 135, 141, 143 Description of 36, 37, 134, 135 Operation of 135 Kate 135, 137 ■ Screenings, accumulation of 139-142 Analyses of 138 Character of 138 Odor 138 Scum, prevention on settling tants by 66, 167 Suspended matter, removal of 64, 65, 136-138 Weand at Sulzberger's, cleaning of .144, 147, 148 Description of 144 Operation of 145, 146 Rate 145, 146 Screenings, accumulation of 146, 147 Analyses of 147 Sewage treated, analyses of ■ 144 Suspended matter, removal of 145, 147 Screenings, see Screens. Scum, chemical precipitation, formation of 104, 106 Comparative formation in various tanks 167 Disposal, see Sludge. Dortmund tanks, accumulation of 66-72 Analyses of 72-74 Emscher tank, accumulation of 83-86 Analyses of 88-90 Grit chamber, accumulation on 56, 57 Analyses of 57 Prevention of by fine screening 66, 167 Secondary settling basin, accumulation of 183, 185 Appearance of '. 183 Secondary Settling Basin, description of 38, 39 Dissolved oxygen in effluent 181, 182, 184 341 Page Secondary Settling Basin, flow period 181 Putrescibility of effluent , 181, 184 Relative stability, effluent 181, 183 Scum, accumulation of 183, 185 Appearance of 183 Sludge, accumulation of 183, 185 Analyses of 186 Appearance of ; 183 Suspended matter, removal of 181, 182 Velocity 181 Sedimentation, see Quiescent Settling, also Chemical Precipita- tion, and Dortmund and Emscher Tanks. Settling Tanks, see Dortmund, Emscher, and Chemical Precipi- tation Tanks. Sewage, Analyses of, see also Appendices and Analyses. Ashland Ave 52 Center Ave 40-44 Individual houses 22, 24 Morgan St 27, 144 Sewers to East and West arms 200, 203 39th St 41, 42 Various American cities 41, 45 Center Ave., alkalinity 48 Biologic oxygen consumption 195-197 Chlorine 47, 48 Fat content 48, 49 Free ammonia 47 Gagings 204-207 Method of sampling 40 Nitrates .■ 47 Nitrites 47 Organic nitrogen 47 Oxygen consumed 47 Physical characteristics 40 Sundays 46 ' Supply to testing station 32 Temperature 49-51 342 Page Sewage, Center Ave., total solids 48 Variations in strength, daily 46 Hourly 45 Seasonal 46, 47 Volatile and fixed matter 49 39tli St., analyses 41, 42 Biologic oxygen consumption 195, 197 Fat content 48 Temperature of 49-51 Total solids 48 Sewers, analyses from outlets to Bast and "West Arms . . 200, 203, 204 Condition of, Stockyards and Packingtown 207, 208 W. 39tli St. and Western Ave. conduit 208, 209 Discharge, estimated, to East and "West Arms 201, 202 Existing, to Bubbly Creek, municipal 200, 201 Private 200, 202 Gagings, Ashland Ave 206, 208 Center Ave 204-207 Individual houses 22, 206, 208, 210 Eobey St 206, 209, 210 W. 39th St. and Western Ave. conduit 209 W. 39th St. and Western Ave. conduit, condition 208 Description 208 Velocities 209 Projects, see Projects. Siegel-Hechinger Co., test 292, 293 Sludge, see also Analyses. Acid treatment, analyses 193 Air drying, see Drying. Calorific value 129-132 Chemical precipitation, accumulation 102, 104, 105 Analyses 106, 107 Comparative accumulation, various tanks 165, 166 Comparative qualities, various tanks 166, 167 Dortmund tanks, accumulation 67-72 Analyses 72-74 Appearance of 72 343 Page Sludge, Drying, amount applied to beds 110-115 Character of sludge applied 110, 111 Climatic influences 118 Depth on beds 111-116 Description of beds 37, 110 Flies 120 Grit chamber, sludge 123 History of beds 118, 119 Mineralization 120-123 Moisture, reduction, on beds 111-115, 117 After removal 111-115, 117 Odor 118 Secondary settling basin, sludge 123 Time required 111-117 Underdrainage , 119, 120 Volume, reduction 112-116 Emscher tank, accumulation of 84-87 Analyses of 87-90 Appearance 90 Digestion 90^ Fat content ' 190 Fertilizing value 128, 129 General methods of treatment 110 Grit chamber, accumulation 53, 54 Analyses 53, 54 Minerialization 120-123 Morgan St. sedimentation tests 29, 30 Pressing, apparatus 123, 124 Filtrate, analyses 127 Method of test 124 Results 125-127 Sludge cake, analyses of 128 Secondary settling basin, accumulation 183, 185 Analyses • ■ •, 1°^ Treatment, see Sludge, Drying, also Pressing. Sprinkling filter, appearance of effluent ^ • ■ • 180 344 Page Sprinkling filter, biologic oxygen consumption, reduction of. .198, 199 Depth, effect of 181 Description of 37, 38, 174 Dissolved oxygen in effluent 179 Dosing device, description 38 Effluent analyses 174, 175 Fat removal 189, 190 Flies 180 Growth in pipes 181 Ice formation 180 Nitrification '. 177 Nozzle clogging 180 Odor 180 Operation 174 Putrescibility of. effluent 177, 178 Rate, gross 174 Yield 174 Relative stability, effluent 177-179 Secondary settling, see Secondary settling basin. Stone '. 37, 181 Surface clogging -. 181 Suspended matter, reduction 174, 176, 177 Temperature 180 Unloading 177, 180 Worms 180 Standard Slaughtering Co., test 294, 295 Stockyards (Union Stockyards and Transit Co.), catch basins. 25, 26 Description 25, 27 Experimental settling tank, Morgan St., description 27 Results 27-29 Sludge 29, 30 General recommendations 29 Laboratory tests on settling 29 Pens 25 Screening, see Screens, Jennings. Sewage 27, 144 345 Page Stockyards and Packingtown, see also Stockyards, and Pack- ing Industiy. Early investigations 34 Firms 3 History of j[ 2 Industries included 7 8 Magnitude of industry 8 9 Packers' committee 7 Preliminary tests 10-13 Present investigations, needed 5, 7 Purpose 5 Seasonal distribution of business 10 Sulzberger & Sons Co., test 296-302 Summary IV-XXII Suspended Matter, acid treatment, removal by 192 Comparative removal by settling devices 163, 164 Comparative retention in devices 163, 164 Chemical precipitation, reduction 100, 101 Dortmund tanks, reduction 61-65 Emscher tank, reduction 78-82 Grit chamber, reduction 54-56 Quiescent settling, reduction 169-173 Screens, reduction by, coarse 134 Jennings 145, 147 Loss of head tests 152-154, 160-162 Rotary .64, 65, 136-138 Weand, Sulzberger's 145, 147 Sprinkling filter, reduction 174, 176, 177 Secondary settling basin, reduction 181, 182 Sewage, Center Ave., fixed 49 Volatile -. 49 Swift & Co., test 303-314 Tanks, see Dortmund, Emscher and Chemical Precipitation. Temperature, air 49-51 Center Ave. sewage 49-51, 168 Effect on scum f oAnation 57, 187 Lake Michigan 51 Sprinkling filter 168, 169, 180 ' 346 Page Temperature, tank effluents 168, 169 39th St. sewage 49-51 Testing Station, Center Ave., Apparatus, chemical precipitation 39 Controlling apparatus 33 Dortmund tanks 33-35 Emscher tank 35, 87 Grit chamber 33 Pumping equipment 32, 33 Screen, coarse 32 Screen house • 37 Screen, rotary . . . . ' 37 Secondary settling basin 38, 39 Sludge beds 37 Sprinkling filter 37, 38 Contributors 7 Location 7, 32 Supply of sewage 32 Total solids. Center Ave. sewage 48 39th St. sewage 48 Union Stockyards and Transit Co., see Stockyards. 39th St. and Western Ave., conduit, deposits in, amount 208 Character of deposits .' 209 Description 208 Location 208 Velocities 209 Western Packing Co., test 315-317 Worms, sprinkling filter 180 Worthen, W. E 3