...
Industrial Wastes
SE INDUSTRY ,.
Sanitary District of Chicago, Ill.
b b
These data indicate the trend toward a heavier calf, hog, and sheep during the war years, but the weight of cattle has not increased similssly. In any event, the exact weight is deairable for computation of losses. >Formany years we have accumulated data on unit losses from Chicago pscking houses, with reaults as shown in Table Il. These data are based on surveys of at least two week eaoh, with inatallation of weirs and automhtic head gages, samples taken every 15 minutes, andyees of 12-hour composites, oomputstion of pounds lost per day, statistics on head and weight of kill, and computation of losses per ton of kill. The kill runs from 50 to 680 tons per 24 hoars; four plants killed only hogs, four only cattle, and the other Idll w&smixed. Water consumption per ton of kill varied from la00 to 8700 d o n s per 24 hours, averaging 4130. The d p s used were &day B.O.D. (biochemical oxygen demand), suspended solids, total nitrogen (organic plus ammonia), and grease. These appear 00 be most informative and are in universal use in industxial waste disposal practice. The average values were: B.O.D., 28.9 pounds per ton of kill; suspended solids, 22.7 pounds per ton of kill; nitrogen, 3.49 pouuds per ton of kill; and grease, 2.64 pounds per ton of kill. The B.O.D. weight is of speoial significance, since it c ~ be n translated into population equivalent by using 0.167 pound per capita per day. This gives 173 persons per ton of kill, an average value under normal conditions of operation. As will be noted later, this may be greatly exceeded in some plants and thus lead to investigations as to why lopses are high, with hoped-for efforts to increase dvage and reduce losses.
Average values for unit losses in packing houses are
29 pounds b i o c h e m i d or;ygen demand, 23 pounde suapended solids, 3.5 pounds nitrogen, and 2.6 pounds grease. These losses can he reduced inside t h e packing house by proper operation and adequate grease-skimming basins. Final losses are sometimes treated by chemical precipitation, but usually several stages of trickling filters (the first stage washable) give the best results. Activated sludge treatment is successful when the wastes are mixed With h u m a n sewage. Wastes from the total United States k i l l were equivalent to 13.67 million population in the year 1945.
T
HE packing house industry, once monopolized by Chicago, has spread far and wide, and many other cities share with Chicago Sandburg’s title “hog butcher for the world”. Table I lists the relative shares of some twenty-one cities in the kill of cattle and hogs in 1944, the banner year. These data show that: Chimgo is still the top market, followed clmly by Omaha; South St. Paul is one of the Nation’s largest centers; New York’s cattle kill is negligible but the hog kill is more than a million animals per year; St. Louis is a growing center; and the industry is widely scattered over the Nation. Wastes from the paclting house industry originate in the various departments, beginning with the stockyards, then from the killing flmr, washing of the WCBBS, washing and cleaning of entrails, paunch manure, blood drainage, tankage, evaporators, hide drainage, hog hair removal, pickling, cooking, rendering, and general cleanup. It is unnecessary to describe all of thase operations, but is s d c i e n t to say that the larger and more complex the packing house, the more effort is made to recover by-products and the less blood, meat, extracts, and fat are lost. Paunch manure is sometimes screened, but soluble contents are not retained, and therefore paunch manure screening does not greatly reduce the ovelcd wastes. Blwd should always he dried and recovered, tankage should be evaporated and sold, rendering losses should be prevented by proper grease-recovery equipment, and solid particles of meat, hair, and offal should be screened and removed. UNIT WSSES
Packing house praetice varies widely, and there is similsr wide varistion in the IOSS~S. In the past such lodes have heen related to head of kill, “hog unit”, or some other unit, but the most useful is per ton of live weight. This value can be approximated by using about 950 pouuds per head of cattle, 210 pounds per calf, 260 pounds per hog, and 90 pounds per sheep or lamb, hut the average live weight per animal varies, as the following figures show (from statisties of the Livestock Branch, U. S. Department of Agriculture):
Yar
CatWa
CdVSs
1930 1935 1940 1946
956 910 940 1148
175 189 191
~
air
Hogs
231
,
227
Sheep or Lamb 82
84
233
86
265
94
Figure 1
637
INDUSTRIAL AND ENGINEERING CHEMISTRY
638
A BWt&T-ting
Packing Hou
As an example of exceasive losses, one pa 87 tons DW day kill had losses of 58.4 D O U U ~ S tion eq&alenk), 49.3 pounds suspended solids, 4.39 pounds nitrogen, and 11.65 pounds grease per ton of .kill, but this plant was notably ine5cient and wrwmaking efforts to improve. Another plant outaide Chicago, in one week's survey, with a mixed kill of 944tonsperday,lost37.3poundsB.O.D. (2!24P.E.),33.8pounds suspended solids, 5.0 pounds nitlogen, and 21.1 pounds grease per ton kill. This plant is installing impioved grease basins, more evaporators, and, pwsibly, vibrating scmens to reduce the losses. On the other hand, a small house near Chicago, killing only a small Imhoff tank to retain solids, lost only calves and ha*g 18.8 poundsB.0.D. (107 P.E.), 3.07pounds~uspendedsolids, 2.7 pounds nitrogen; and less than 0.1 pound grease per ton of kill. The very low loss of grea8e was probafi due. to the kiu, entirely calves. Thus these unit values can be used to estimate the efficiencyof a plant, provided the plant doee not include manufacture of glue, soap, gelak, or unusual by-products. The question is often aaked: How ,do .unit lasses vary with kills of cattle in contrast to hogs? We compared four houses with kill of one type, hogs or cattle; the rdts,(Table 111)show more water used for hoe, somewhut higher B.O.D., less suspended solids, about the same nitrogen, add more grease per ton of hogs, than per ton of cattle. These conclusions are still rather uncertain as they are based on iDsu5icient data, but they do indicate trends. However, the unit losses for mixed kills are more conclusive. .. . REDUCTION OF LOSSES
Eternsl vigilance is the price of' dciency in, packing house operation. The industry has always 'prided itself on its e 5 cieucy, using the time-worn slogan that everything is recovered b t the squeal; but operating alertnees, plus proper equipment, is necessary to prevent losses to the sewers that may seem insigni6-t to the pwlier but exceesive to the sanitmy engineer or chemist. No matter bow efficient the pachr may be, he still discharga wastes more concentrated than any city sewage and thus creates a waste disposal problem. How can these losses be prevented? , Probably the 'most helpful abatement meashre is the salvage '&by'nieam of peens, vacuators, skimming basins, or tfap inside packing house, before wastes from the rendering department, s a w e kitchen, oil house, cooldng department, or other-grease&mring operations are discharged to the @ewer and dilubtl by condeuser water, paunch contentS, wash water, and boiler plant wastes. Mortenson, of Swift and Company, Ino.,
OF
urges separation (1%') and states that a wd-constructed and operated basin should not discharge more than 0.2 pound of skimmable grease per ton of kill, as determined by an ingenious method of testing devised by him. G r e w separators, according to Mortenaon (IS), should be only 2 to 4 feet deep, not too wide, with pwaibly one half to one hour detection, velocity 1to 2 feet per minute, and arrangement for easy removal of greases by hand skimming. Mecbsnicsl devices include continuous r e m o d of grease from the surfam and settbga from the bottom. A h is sometimes used to cause' grease to come to the surfaxe; ala0 vacuum and, more recently, preasure tanks are utilized for introducing air bubbles which bring grease to the surfam. Unfortunately such bubbles also bring nonfatty suspended solids alang with the grease and thus lower its quality. Losses of nitrogen betray poor opation in the tankage kouae, killing floor, blood recovery, and cook house. If insufficientevaporative capacity is provided, or what is available is not operatted properly. tank water, entrainment losses, blood, and meat pard to the sewer to increase the nitwgen'losses. or8 of sufficient capacity should he installed ch day's production of tank watar. This meum gallons per hour capwity for a Boo-ton house. or6 should-he'larm enoneb - to handle all tmhee - on a %hour hasis, so that no feed tankage remains over the worldng day. It hegins to spoil in 48 hours so that foaming, vapor laas, and entrainment become troublesome. Screens are used on munch manure. cuttina and trimmina flmr wastes, hair losses,-and sludges. Electricaiy vibrated fine screens seem to operate well and are coming into use. After recoveries are made of the specSc operation waste, it may still be possible to skim grease from final settling tmh
-
Table I. Slaughter of Cattle and Hogn in Public Stockyards of I&w Cities, 194% city Baltimore Chioago Cincinnati D*tl"er Detroit Fort Worth Indiana olia .brew &ty Kansas c i t y LoaA slas Mih& , , New York OLlahorns c i t y Omaha Pittabur h St. .os& st. LOUIS stookyarda s t . Lovia Sioux City south s t . Paul Wiahita 47 D t h W aitias
cattle 100.433 1,468.12? 254 202 3143981 193.686 493 335 1893433 197 826 806;9lS
366.s40
.
.
Total
Hogs 412 893 6,566:691 899,384 926 332 304:307 969.813 1,349 289 311:491 1.307.080
220 140
216 872
36:873 309.627 1,041 381 130:616 412 288 626:374 45.948 537 652 7923330 199,218 1,660,170
74447 1,036,645 832.406 3.176.893 647 770 1,770:931 2,861,662 687 399 ' a;ow38zz 2.Wl 841 4603124 4.067,649
10,382,119
33,242,919
Table II. Unit Packinp: - House Loseea, C h i ~.a ~ o Tom/ Type 24 Hr. E088 51 114 EOMixed, 127 E088 139 Cattle 148 Cattle 166 Cattle 168 Mired 185 Horn 190 Mixed 303 csttle a97 M i d 429 661 M i d ~ i ~ e d 680
Gal./Ton 6600 2200 26W 4900 19W 2800 2WO
B.O.D. 36.0 30.1
,
.25.4
2800
4600 46W 6200
66W
'
2600
moo
'
26.2 41.5 31.4 21.0 39.4 19.6 33.4 20.0 29.4, 13.0 38.5
Pounds/Ton BW+d soh& Nitmien 24.0 5.34 18.2 2.68 9.1 4.06 19.6 2.50 29.6 4.47 29.5 4.02 19.9 2.04 18.8 6.18 14.3 2.93 29.9 4.37 22.0 2.16. 3.41 26.5 1.68 12.6 44.3 4.20
Qraksa 1.80 4.61 2.88 6.66 1.35 3.68 2.01 1.20 0.54
4.00 1.10 3.W 1.00 4.m
i t
640
INDUSTRIAL AND ENGINEERING CHEMISTRY
Vol. 39, No. 5
Oliver Filters for Dewatering .kti\atecl Sliidge f r o m I'acliing Ilorise Wastes, plus Sewage
after wastes cool sumenhat and a larger suriace area is ai-ailablca for grease accumulation. This procedure is more in the field of sewage treatment and no recoveries are likely. FINAL TREATIIENT
.liter all reasonable recoveries are made in the pacliing llvuse itsc,lf, the degree to which the residual wastes must be t r e a t d depends upon the conditions of dilution or, possibly, legal y e quirements which might specify so-called complete bioloyicai treatment. The various steps available are: coarse acroens, fine screens, sedimentation (or vacuator), chemical precipitation, high-rate trickling filters, activated sludge, low-rat(%trickling filters, chlorination, and dilution. There are packing house waste-treatment works :it mail? !oralities which use these processes. Practically all include setlin~c~ntation, but, in many this is but the first st,ep. S o pretreatment escept a litt,le grease skimming is practiced at C'hicago, where all packing house rrastes are treated by the activakd sludge process, in combination with sewage from 1,200,000 people, a t the Southwest Treatment Works. At Fort Worth, Tex., only sedimentation has been employed for many years. Chemical treatment is in use a t a number of places: Zinc chloride (Domogolla's process) was used a t the plant of Oscar l l a y e r and Company a t Xadison, \\-is.; chlorine alone, as patented by Halvorson, a t George d. Hormel and Company, Austin, LIinn. ; ferric sulfate and sulfuric acid a t several Swift plants; ferric chloride by Kober Company a t Elgin, Ill.; and ferric salts plus lime, for awhile by Armour ant1 Company a t Ccdar Rapids, Iowa, and also hy Tovrea Packing Company a t Phoenix, hriz. Chemical treatment suffices for the stronger uxiste.s froin a packing house but is not suitable for t h t n-eaker ivustes or for a high degree of treatment. For esample, chlorine treatment at the Hormel plant was effective only on 1 fresh concentrated wast,es, and later alum treatnie~it rcnioved only 3 0 5 of the
13.0.11. ant1 76(; of t h c suspended soIi(1s. Ziiic chluri,lt~ a-ed w i t h concentwtcd va5tes at t'he Oicar SIayer plant, folloived 115- linw t r c ~ ~ t n i ~ for n t all wastes, in an attempt to produce a n efflucnr n.it!i !cis than 260 p . p . i n Thi. \vas not always (lone. J h e :dime is now used, although i t i, not so efficient as zinc ciili ii,itlc. On the other hand, IUridye (3,rc,porteci that the iiw of chlorine and fcrric chloride riduced the B.O.D. of packing house Tt-aste from 2700 to 310 p.p.ni., and llortenson stated (131 that 500
pouiid. ferric sulfate plus 1000-2000 pound,? sulfuric acid per million gallon^. u t ii pH of 4.8, reduced the B.O.D. t o 80 p.p.ni. a t a S r i f t plant (L&e Charles, La., or Sloultrie, Ga.1. 13 that trratincnt \\-ascompleted by a trickling filter. Tlic Tuvrea plmt at Phoenix used ferric chloride, made irom c.liloriric and scrap iron, to reduce B.O.D. from 1-150 t i t 200 p . p . 111. Trickling filter>, preceded by a tvaahable high rate fiiLcr, Iiitvr p r o v ( d most suitable for packing 1iou.e wastw. Lcvintb xnil
Table 111. Comparison of Pacliiug IIouse Imsres for k i l l of Hogs and Cattle Poiiiidi _ Tc,n _ _ _ _ _ ~ ~ ~. 'TC811.
24 Hr.
(;,'I
Ton
B.O.D.
Suspended wiids
Zltrcipeu
(;rra.e
HOC?>
51 139 114 190
5500 4900 2200 4600
36.0 26.2 30.1 33.4
148
1900 2800 2000 6200 :3225
41 5
165 16s 30T .iY,
31 4 21 0 20 0 28.5
24 0 19 6 la 2 .I 1 0
I-
29 6 20 3 19 9 3.) 0 23 3
--
.j :il
1 5U 5 tit1 4 61 1 10
1 4: 4 01
1 .'3.5 3 .5b 2 01 1 .10 2 01
2 .TO 2.58 2 16
2 04
2 16 :3 1;
M a y 1947 Table 1\
I N D U S T R I A L A N D ENGINEERING CHEMISTRY
.
Federal Inspection Data o n 1,irestoc.h k i l l , 19:W-4.5
c~oniparcd with that under federal insprction, was as follon-s (in thousands) : Cattle
20,223 20,466 19,815 21,473 21,385 17,262 20.886 18,S4? 20.014 21.130 2 3 , 4 10 24,401 ?6,1.'.5 '3 0 , 5 .0i .'3 3 ,-I1:i 28,lIi
:30,164
27,358 35,669 36,775 40,676 45,632 47,395 43,618
:.5
33.i00 34,100
33.000 35,600
5
SR 90
71
29,300 :31,900 3i.ion 33.800 35,200 39,000 40,700
6 19 6 18 4 '(8 fi 0:' 3 :i8 i 76 6 0'3 6 7.5 7 04
50,900
s
35.i00
s
11 hl 9 64 8 11
46,87i
5,5,iO(J 46,900
67 0
fii 1 . .
63 66 69 66 70
8 n ; 7.89
67,800
76,100 79.000 72.700
6
4 1 0 5 6 4 Ti
10 29 10.60 11 i 3
59,500 61,300
Tutal l'ed ins.
21,372 14,538
Calves 13,488 7,020
Hogs 68,511 40,960
Sheep T o t a l T t . , and Tons/ Lambs Day 72,700 24,642 46,900 21,220
"0 of Total 6 4 '(5
...
45,600
.50.300
641
13 16 13.67 12.58
Selsoii (8) demonstrated the backn.aA high-rate filter at the old plant of Jacob E. Decker and Sons in \lason City, Iowa, and it has since been used a t Austin, Minn., Kest Fsrgo, S . Dak., and Sioiix Falls, S. Dak., with good results. These plants include flocculators. two stages of filters, and, a t Sioux Falls, final treatment 11y activated sludge. This has given rise to a problem of floating sludge in the final tanks due to nitrate reduction and production of bubbles of nitrogen which came tlie sludge to float off with the effluent. However, I)>- prompt remoral of sludge from the settling tanks, flotation is p r a c t i d y eliniinated. A year's study at Sious Falls failed to develop any inmiis of prevc,nting .sludge flotation by addition of chemicals. l l a n y cities rcccire some compeniation floni the jxtckers for trwting packing house i m s t e s . The prohl(m iwastes have B.O.D. up t o 1800-2000 p.p.m., wspcnded qolids of 1000 to 2000 p,p.m,, and more than 100 p.p.m. nitrogen. Only hy ti com1)ination of processes does it appear possitk to bring the R.O.D. of 50 p.p.ni. or Ieiq, hut this is actu:illy ral plants. At Chicago the coinhined packing hou-c-*v\wqg: t4lucnt has a B.O.D. of only 10 to I 5 p.p.m.
Csing the total kill and average weight for various years since 1930, the tonnages and population equivalents shown in Table Lr are computed. The population equivalents run from 7.89 millions i n 1935 to the niasinium of 13.67 millions in 1944, decreasing t o 12.58 millions in 1945. I n Table I V the perccntage of total ltill under federal inspection is shonn to run from 63.1 in 1935 to 70.5 in 1944, decreasing t o 64.5 in 1945. Thus 30 t,o 3SCc of the total is local, including uninspected slaughter houses, retail killing, and even farm killing. Howtsver, this adds to strimn pollut'ion, and the total figures may be considered the national total pollution due to packing houses, slaughter houses, and farm kill. The total population is abclut 10% of the hunian population of the United States. The human population using sewer; is only around 72 niillion. The maximum population equivalent of federally inspected packing house \Task, 9.64 million in 1945 (Figure l), is 1 3 . 4 5 of this total, somewhat more than the over-all figure. Although the total population of packing hcluse and slaughter house wastes reached the value of 13.67 million in 1945, it is still less than the over-all effect of other types of wastes. The alcohol program during the war produced nastes n-ith a population equivalent of 27 niillion, from t'he 1944 program of 1,192,000 gallons of 190-proof alcohol per day. Of course, this caine largely from the demands of the synthetic rubber indust,ry and might be considered an emergency or wartime load. The pulp and paper and the food product' industries probably contribute Tvastes with even greater populat,ion equivalent.s, hut data are not a t hand to comput'c these totals. Thus, although packing house wastes cannot be designated as the Sation's leading industrial waste problem, they are widely responsible for stream pollut'ion and create difficult problems of sewage disposal a t such centers as Chicago, Sioux Falls, Aust,in, Madison, Indianapolis, and Fort Vorth. Any processes of salvage Tvithin the packing house, such as dry rendering, improved grease recovery, recovery of paunch manurc, or increased evaporation of tankage are n-elcomed by public authoritiv n-110 art: ?onfronted with the treatment of such wastes. BIBLIOGRAPHY (1) Bragbtad, It. I:., niid (19371.
Biad,,ey, I,.,Seicage I l . o ~ k s J . , 9 , 959
( 2 ) C'hiltlres~,G . L., .Seci.aye F o r k s E ~ Qa 7. d .lIunic. S a / t i t . . 12, 313 NATIONAL PROBLEM
Speculation on the extent of the packing house waste problem in tlie United States can be made more or less quantitatively from Drpartment of Agriculture dat,a for kill, available since 1930, and thc relation of 173 persons per ton as an average value. Taljle II' gives the pounds of kill per year since 1930, computed to tons per day and population equivalent, under federal inspection. These data are presented in Figure 1. I n tlie 1930's the populat,ion equivalent remained around 6.0 million, but after 1941 and during the war there was a great incrcasv, i~cachinga maximum of 9.64 million in 1944 and dropping to 8.11 million in 1945. The great increase from 1942 through 1945 is noteworthy. This estimate is based on the kill under federal inspection. I n addition therc is a large uninspected kill, and numerous local slaughter houses account for a large kill. The U. S. Department of .Igriculture has estimated this additional kill, even down to slaughter on farms. For example, in 1945 the total slaughter, as
(1941;.
(31 P:ldI.idge. E. I,'.. 3Iich. Eng. E x p t . drrt., Bziil. g2 (1935). icage n70rl;s . I . , 11, 1045 ( i g 3 g ) .
Iiopkiiis. G. J., Pichlic Il.orks, 75, 23 (1944). (7) Howvson. L. R.. T17tLLer 1T.o~X.s & Sewage, 87, 217 (1940). (8) Levine, >I., SeLou, F,G.. mid Dye, E., Iowa Eng. Expt. Sta., Rzill. 130 (1037). (9) Malilie, 17. S.. Seicage T170i.ks J . , 15, 521 (19531. (10) Milling, M. A , . and Poole. B. d.,I b i d , 10, 738 ( 1 9 3 8 ~ . (11) 3fohlmall. F.TI-.. ISD. ~ S GC.H E M . , 18, 107G (1926). (12) Mortenson, E. S . . .\-al?'onal Provisioner, Apr;l 24-11ay 1, 1943. (13) llortenson, E. S . . 2nd Industrial R-aqte Conference, Purdue Univ., E x t . Series 60 (1946). (14) Pearse, L., and Dilliiig, -1.W., Rept. on Industrial !Tastes from Stockj-ards and Packingtown in Chicago (1921). (15) Sanders, 31. D., U. S.Patent 2,328,361 (1944). (16) 5. S. Puhlic Health Seriice, I n d u s t h l Waste Guides, Ohio River Pollution Control, 78th Congr., House Doc. 266. Supp. (ti)
D . , 11.1'3 (1944). PRESESTED before t h e Industrial K a s t e Symposiurn a t t h e 1 1 1 t h Meeting of t h e . l u m i c a s CHEVICAL SOCIETS,.Itlantic City, S . J.
