1076
INDUSTRIAL A N D ENGINEERING CHEMISTRY
Even this attention is only required at long intervals if the siphon is so set that it extends nearly to the bottom of the filter and the jar and filter are large. It is sometimes advantageous to replace the Iower funnel with a thistle tube the wide end of which is fitted over the tip of the upper funnel while its small end extends into the receiver.
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A convenient means for filling the siphon is offered by the side tube, T , placed a t the top of the siphon. By closing the end of the siphon which is to be in the filter, placing the other end in the liquid in the jar, and applying gentIe suction at T,the liquid rises into X and flows over into the outer end until the tube is full. This method is not satisfactory if the bore of the siphon is less than about 7 mm.
Treatment of Packing-House, Tannery, and C orn -Pr od u cts Wastes”* By F. W. Mohlman THES A N I T A R Y DISTRICTO F CHICAGO, CHICAGO, I L L
Method which has been used at Chicago f o r evaluating the e$ect of the major industrial wastes, with results experimental treatment of these wastes during the past jijteen years HE problems of providing a safe, palatable water supply and of satisfactorily disposing of this water after it has been used and discharged as sewage are greatly complicated by the presence of industrial wastes. Industrial wastes are often discharged directly into lakes or water courses, in which case the treatment problem may be even more difficult, owing to inhibitory substances in the waste which prevent or interfere with biological processes of treatment. Sometimes evaporation is the only solution of the problem. Industrial wastes may be divided broadly into those which affect the quality or treatment of water supplies, and those which produce nuisance and kill fish in streams not used for water supply. There are, of course, wastes which fall under both classifications, but it is generally possible to place certain types of wastes in one group or the other by consideration of their oxygen demand and ability to support bacterial life. I n the development of the disposal of the sewage from the $anitary District of Chicago, industrial wastes of the second type-liquid organic wastes with excessive oxygen demand and high bacterial content-have been of most importance. There is a water-supply problem in the Calumet District due to the obnoxious taste of wastes from by-products coke plants in the water chlorinated a t the 68th Street Pumping Station, but this problem is aside from the major one of the treatment of sewage and wastes now diverted through the drainage canal into the Des Plaines-Illinois Rivers. It has been known for many years that the industrial wastes greatly augment and complicate the sewage load contributed by the human population of the Sanitary District. I n fact, there are very few cities which do not have this same problem, though usually in lesser degree than Chicago. A complete plan for sewage treatment must take account of these wastes, and their effect should be measured and put upon the same basis as the human sewage. The total load of pollution may then be separated into human and industrial wastes, and the effect of treatment of a n industrial waste expressed in its human equivalent. This paper deals with the method that
T
1 Presented a s part of the Disposal of Trade Wastes Symposium a t the Midwest Regional Meeting of the American Chemical Society, Madison, Wis., M a y 27 to 29, 1926. 2 The investigation of the industrial wastes with the experimental work has been carried on b y the Sanitary Division of the Engineering Department of t h e Sanitary District of Chicago, of which E. J. Kelly is chief engineer, under the direction of Langdon Pearse, sanitary engineer, and F. W. Mohlman, chief chemist. The Packingtown investigation was begun in 1911 when George M. Wisner was chief engineer and Arthur Lederer was chief chemist. Mr. Wisner became consulting engineer in 1920.
of
has been used a t Chicago for evaluating the effect of the major industrial wastes, and the results of experimental treatment of these wastes during the past fifteen years, Oxygen Demand-Population Equivalents The results of sanitary chemical determinations such as oxygen consumed, albuminoid nitrogen, ammonia nitrogen, and total solids have little relation to those conditions in a stream which give rise to nuisance and kill fish. It is well known, however, that the production of nuisance and the killing of fish is primarily due to absence of dissolved oxygen in the stream. Consequently, i t is very desirable to place the load of pollution on a n oxygen basis and to balance the oxygen requirements against the oxygen available in the diluting water. A deficiency must be supplied by sewage treatment. Industrial wastes, whose oxygen demand is known, may be placed on the same basis as human sewage with regard to stream pollution or treatment, provided Tve know the proper per capita factor for oxygen demand. This factor was determined by tests a t the 39th Street Pumping Station in 1914 and at the Des Plaines Treatment Works in 1925 (Table I). Additional tests a t the Calumet Treatment Works in 1925 and at the 39th Street Pumping Station in 1920 support these data. The factor that has been used in the industrial-waste work has been 0.244 pound oxygen per capita per 24 hours (extrapolated 20-day demand). For shorter periods of incubation a t 20’ C., the following factors are used: Days 2 5
10
Pounds per capita 0.090 0 167 0.220
Population Equivalent of Industrial Wastes The three major sources of industrial wastes in the Sanitary District are packing-houses, the manufacture of corn products, and tanneries. The packing-house wastes are concentrated in an area of about one square mile on the South Side, discharged from approximately thirty individual houses in Packingtown; corn-products wastes are discharged by the main plant of the Corn Products Refining Company at Argo; tannery wastes are discharged by approximately twenty-eight tanneries scattered along the Korth Branch of the Chicago River. There are many industrial wastes of lesser significance, most of which have been investigated and evaluated. The results of the surveys of the packing-house and cornproducts wastes are shown in Tables I1 and 111.
I,FTDUSTRIa4LAND ENGINEERING CHEMISTRY
October, 1926
T a b l e I-Basis for C o m p u t i n g Oxygen D e m a n d in P o u n d s p e r C a p i t a (Average of 350 daily composite samples during the year) Pumpage -OXYGEN DEMAND-? Year Ga1./24 hours P. p. m. Lbs /24 hours Population 39th S t . Tests 10-day 10-day 1914 71,063,000 121 71,800 324,000 0 22 pound oxygen per capita (IO-day demand) or 0.244 I total demand) 324,000 Des Plaines Treatment Works 5-day 20-day" 5-day 20-day 1925 5,130,400 213 311 9107 13.300 49,800 9107 0 183 pound oxygen per capita (5-day demand) -= or 0.267 (20-day demand) 49,800 1.46 times 5-day demand ~
~
T a b l e 11-Packing-House Wastes. Daily Discharge of S u s p e n d e d M a t t e r , O r g a n i c Nitrogen, and Biochemical Oxygen D e m a n d (Calculated from individual gagings and analyses--1917) POUNDS PER 24 HOURS PER CEKT OF TOTAL Susp. Organic Oxygen Susp. Organic Oxygen Firm matter nitrogen demand matter nitrogen demand 52,170 3,756 74,050 39.67 25.24 30.53 Swift 25,120 2,436 48,370 19.10 18.32 19.94 Armour 18,880 2,058 36,000 14.34 13.48 14.84 Morris 9.12 7.69 10.25 10,110 1,363 22,130 Wilson 2.86 3.74 9,070 2.76 3,620 379 Hammond 1.19 1.02 2.68 2,460 3,520 158 Union Stock Yards 1.77 2.74 2.31 6,640 235 3,030 Libby, McNeill & Libby :3.98 2.69 6,520 1.67 528 2,200 Darling 1.08 2.39 144 5,800 1.13 1,480 Guggenheim 1.45 1.37 3,320 1.10 193 1,450 Independent Packing 7 . 5 5 15.38 11.62 9,950 2,048 28,210 21 smaller firms
__________---
TOTAL 131,500 13,298 242.570 100 00 100 no 10-day demand Population equivalent: T a b l e 111-Corn
a
1oo.00
Products Testing Station.
Month Gallons per 1922 24 hours January 14,268,000 February 13,596,000 March 13,570,000 April 14,121,000 September 17,380,000 October 15,253,000 November 14,030,000 December 13,350,000 Average 14,450,000 5-day is 78 per cent of total.
Population equivalent:
Oxygen D e m a n d Total OXYGEN DEMANDoxygen demand 5-day Totalo Lbs./24 hours 540 692 81,730 749 960 109 150 616 789 89:Olo 593 760 89,150 524 672 96,800 538 690 87,660 515 660 77,120 559 717 80,440 ... 740 88,860
':,":"E
= 370,000
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The oxygen demand, 10 days a t 20" C., was 242,5iO pounds per 24 hours, equivalent to a human population of 1,100,000 people. CORN PRODUCTS COMPANYTESTS-since January, 1922, practically continuous tests (except from May to August, 1922) have been made a t the Corn Products plant a t Argo. The wastes are measured by flowmeters, samples are collected every halfminute by automatic samplers, and oxygen demand determinations are calculated t o pounds per 24 hours. As shown in Table 111, the daily oxygen requirement (20-day demand) in 1922 was 88,860 pounds, equivalent t o the oxygen demand of the sewage from 370,000 people. TANNERY TESTS-In 1920 and 1921 tests similar to the 1917 Packingtown tests were made a t twenty-eight tanneries on the North Side. The total discharge of suspendea solids, organic nitrogen, and oxygen demand (10 days a t 20" C.) were, respectively, 22,400, 2180, and 14,720 pounds per 24 hours. The population equivalent of these wastes, based on oxygen demand, . . 14 720 was accordingly = 67,000 people. 0.22
The volumes and weights of constituents discharged in these three major wastes are summarized in Table IV. The total amount of oxygen required per 24 hours by these three wastes, calculated to 20-day demand for the year 1920, was approximately 360,000 pounds per 24 hours. I n 1920 the human population of the Sanitary District was 3,000,000, with an oxygen requirement of 732,000 pounds per 24 hours. The three industrial wastes accordingly added 50 per cent to the load of human sewage. Operation of Testing Stations
Realizing the necessity for investigating methods of treatment of these wastes, the Sanitary District has operated testing stations on the three types of wastes over a number of years. The tests have been most elaborate and detailed. Packing-house wastes were studied a t the Stockyards Testing Station from 1912 to 1918. Results of these studies have been published in two reports, the first of 340 and the second of 260 pages. Tannery wastes were investigated a t the Tannery Testing Station in 1920-1922. Corn-products wastes were investigated at the Corn Products Testing Station from 1920
C o r n P r o d u c t s Refining Co., Argo, Ill.
PACKING-HOUSE WASTE TESTS--I~ 1917 tests were made extending over several weeks a t each of some thirty-one packinghouse plants. The wastes were measured by weirs, composite samples were analyzed consisting of proportionate volumes of samples collected a t intervals of from 10 to 15 minutes, and weights of suspended solids, organic nitrogen, and oxygen demand per 24 hours were computed. Total weights were summarized and each plant was evaluated in percentage of the total, as shown in Table 11.
to date. No printed reports have been issued on the-two latter investigations. It is obviously impossible to cover more than a very brief summary of the results in this paper. All processes lvhich were investigated, promised even a faint possibility of even though such processes might not be adaptable to Chicago conditions. The results are therefore of general interest.
INDUSTRIAL AND ENGINEERING CHEMISTRY
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P a c k i n g t o w n Testing Station
The Packingtown Testing Station was operated in two periods, the first from 1912 to 1914, the second from 1915 to 1918. The development of the activated sludge process in 1914 led to the continuation of the tests in the second period. Packing-house wastes were pumped from the Center Avenue sewer, t,he main outfall a t the stockyards, to an orifice box for measurement and distribution to the various tanks and filters. Approximately 250,000 gallons per day were pumped to the first orifice box. The waste was warm and quite concentrated. Table IV-Summary, Waste Packingtown Corn-products Tanneries 10-day demand.
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Grease clogged the screen frequently, b u t could be removed by washing with hot water and soda ash. SEDIMENTATION-The Imhoff tank gave satisfactory results, with a removal of approximately 65 per cent of suspended matter and 35 per cent of the oxygen demand. The detention period was from 1to 3 hours. FILTRATION-The trickling filter produced a highly nitrified effluent, which could be well clarified by secondary sedimentation. The oxygen demand was reduced from 630 t o 120 p. p. m., a reduction of 81 per cent, or based on the crude sewage with a demand of 990 p. p. m. the total reduction was 88 per cent. The oxygen demand of the filter effluent varied from 50 to 75 p. p. m. in midsummer up to 200 p. p. m. in January or February. Nitrates varied inversely, from 5 to 10 p. p. m. in winter up to 20
Discharge of Packing-House, Corn-Products, a n d Tannery Wastes as Measured -PARTS PER MILLIOK--POUNDS PER 24 HOURS--Suspended Organic Oxygen Suspended Organic Oxygen solids nitrogen demand solids nitrogen demand 490 49.3 950a 131,500 13 300 242,570 204 50.4 7355 24,700 6:090 88,860 885a 22,400 2,180 14,720 1,340 131.0
Year of tests Ga1./24 hours 1917 32,000,000 1922 14,500,000 1921 2,000,000 b 20-day demand.
Processes of treatment studied included fine screening, sedimentation, chemical precipitation, trickling filters, and activated sludge. Aside from concentration and warmth it was found that the wastes were similar to domestic sewage in biological properties, and hence amenable to biological processes of treatment. Screening was found to be necessary before activated-sludge treatment, and both screening and sedimentation before trickling filters. With increased knowledge of the activatedsludge process a t the present time, it is probable that both screening and sedimentation might be recommended to precede activated-sludge treatment. Sedimentation in Imhoff tanks was found to be the most satisfactory process for clarification. Chemical precipitation removed more suspended solids, but the volume of sludge was excessive, ill-smelling, and hard to dry. Trickling filters containing 6 inches of 2- to 4-inch stone overlaid by 5 feet 6 inches of 11/4- to 2-inch stone gave satisfactory, nitrified effluents a t rates of from 600,000 to 1,000,000 gallons per acre per day. Activated-sludge treatment was studied from January 10, 1916, to February 12, 1918. Reaeration and resettling of sludge, various types of settling tanks, filtration of sludge, and recovery of sludge were studied in detail. The operation of the aeration tanks was divided into twenty-nine periods, in which various detention periods and quantities of air were used.
Results of Operation Typical and representative analyses of the crude waste and the various effluents produced are shown in Table V. Table V-Analyses
of Raw Sewage a n d E m u e n t s . Stockyards Testing Station Packing- , EFFLUENT house Trickling Activated wastes Screen Imhoff filter sludge Determination P,p.m. P.p.m.P.p.m. P,p.m. P.p.m. 22.0 29.0 16.0 10.0 Ammonia nitrogen 22.0 75.0 60.0 20.0 10.0 Organic nitrogen 79.0 0.5 0.2 2.2 1. o Nitrite nitrogen 0.5 3.0 1.7 16.4 5.0 Nitrate nitrogen 3.0 180 .... 268 240 Oxygen consumed 50 1100 1100 1100 1100 Chlorine 1100 212 240 200 .... Alkalinity 212 515 210 75 30 Suspended solids 605 930 630 120 50 Oxygen demand (10-days) 990
Operating results and percentage removals are discussed below: SCRE~NING-Arotary screen covered with wire mesh removed most of the coarse material such as hair, flesh, paunch manure, and floating solids. The 20-mesh removed about 9 per cent of the suspended matter, the 30-mesh about 19 per cent. No appreciable reduction of the oxygen demand was effected.
to 30 p. p. m. in summer. The filter unloaded continuously, there was little evidence of pooling, and very little nuisance from flies or odors. The area of filters required for the total volume of waste would, however, be enormous. At 750,000 gallons per acre per day 43 acres would be required. ACTIVATED SLUDGE-Activated-sludge treatment produced a very satisfactory effluent. An aeration period of 9.0 hours and 3.5 cubic feet of air per gallon were required. It was necessary t o increase the air up t o 4 or 5 cubic feet per gallon in winter, and even with this amount nitrates were not produced. I n summer nitrates averaged 5 t o 7 parts per million. The suspended solids and oxygen demand of the effluent were considerably less than in the settled trickling filter effluent. The activated-sludge effluent was in general superior t o the settled filter effluent. SCREENINGS AND SLUDGE-Screenings after draining contained 81 per cent moisture. On a dry basis they contained 95.3 per cent volatile matter, 4.7 per cent ash, 2.18 per cent nitrogen, and 5.93 per cent ether extract. Imhoff sludge contained about 90 per cent moisture as removed from the tank, which was only 17 feet deep. The dried sludge contained 75 per cent volatile matter, 25 per cent ash, and 2.72 per cent nitrogen. Secondary tank sludge contained about 94 per cent moisture. On the dry basis it contained 65 per cent volatile matter, 35 per cent fixed, and 3.50 to 4.00 per cent nitrogen. It would not dry well on sand beds. Activated sludge would not settle to less than 98 per cent moisture, would not dry on sand beds, and could only be dewatered by filter-pressing. The nitrogen content of the dry sludge was quite low, averaging from 4.2 t o 4.5 per cent. Sludge pressing by means of a recessed-plate press was not very satisfactory. Sulfuric acid was used (June, 1917) and found to increase the rate of filtration considerably, but no determinations of pH were made. It was concluded a t t h a t time t h a t the sludge could be filter-pressed successfully with the use of acid up to about 2 cc. of 60" Be. acid per gallon of sludge.
Recommendations for Treatment of Packing-House Wastes The activated-sludge process was recommended for treatment of Packingtown wastes, and in 1917 preliminary plans were drawn up for a n activated-sludge plant. These plans were revised in 1921 and a tentative agreement was drawn up between the Packingtown representatives and the Sanitary District, whereby the former agreed to pay 60 per cent of the cost of construction and the latter 40 per cent This offer was later withdrawn by the packers. I n 1924 the Sanitary District brought suit to enjoin the packers from discharging wastes into the drainage canal and its tributaries. The matter is still in litigation. The site immediately available in Packingtown for activated-sludge treatment is limited in size. Transportation of the waste mixed with human sewage to the Southwest Side Treatment Works has been considered, using for treatment Imhoff tanks and trickling filters or activated sludge. If it is decided not to recover the activated sludge for fertilizer, it may be handled by digestion in Imhoff tanks and
diying on saand hedr. Tbe decision awaits operating experience a t Milwaukee and Chicago. T a n n e r y Testing Station
Tannery wastes have created very objectionalilc conditiolis in tlie North Branch of t.he Chicago R.iver for many years. In 1920 a test,ing station as built at the largest of these plants, the Griess-Pfleger Tannory. Practically all of the thirty tanneries in Chicago usc the cbrome process. At the time of t.lie tests the Griess-I'fleger Tannery ernploved about 550 ~nen.and ormated about 25 days per month. io iiours per day. The lnontl~lytannage vas k,600 pounds of calfskins and 1,300,000 pounds of cowhides. The losses per 1000 pounds of hides w-ere 67.5 pounds suspended solids, 4.9 pounds organic nitrogen. and 36.1 paunds oxygen dr~mand, equivalent to the sewage of 164 people. Wastes l e r e of t,hree t.yps: (I) soak liquors, in which dried or salted hides were soaked or washed; (2) lime liquom, from lirriing pits ani1 druins; and (3) ban liquors, from the chrome tanning process. The average volumes
punched with inch round holes, s/Is inch on centers. The screen was driven at 45 r. p. m., giving a peripheral speed of 250 feet per minute. The submerged area was 35 ner cent of the t o t a i area. The screen was saf-cleaning, but
