L i q u i d Industrial Wastes facture. Through education, the dairy plant managers and employees are becoming more and more waste conscious and, therefore, more active in waste prevention. Where treatment can be provided economically in combination with city waste, this is preferred t o separate industrial waste treatment. I n general, for separate milk waste treatment plants, the high-rate recirculating trickle filters have been found costly to install but quite satisfactory in operation when properly built and maintained. Attempts are being made to develop some type of simplified aeration plant, with or without activated sludge, t h a t will give satisfactory results a t low operating costs. The problem of economical and satisfactory disposal of sludge ‘ from trickle filters and aeration units is still t o be solved.
Literature Cited (1) Backmeyer, D., Proc. 6th 2nd. Waste Conf., Purdue Univ., 34, No. 4, 411 (1949).
(2) . , Dairv Sanitation Engineers Committee. “Dairv Waste-Saving a& Treatment Guide for Milk Plant OperrttoEs,” Harrisburg Pa., Pa. Assoo. Milk Dealers, Inc., 1950. (3) Hasfurther, W. A,, and Klassen, C. W., Proc. 6th 2nd. Waste conf., Purdue univ., 34, 424 (1949).
(4) Hoover, S. R., Jasewicz, Lenore, Pepinsky, J. B., and Porges, N., Sewage and 2nd. Wastes, 23, No. 2, 167 (February 1951). ( 5 ) Hoover, S. R., and Porges, N., Proc. 6th 2nd. Waste Conf., Purdue Univ., 34, 137 (1949). (6) Johnson, W. S., Ibid., 4th Conf., 33, No. 4, 54 (1948). (7) MoKee, F. J., Sewage and Ind. Wastes, 22, No. 8 , 1041 (August 1950). (8) Neil, D. G., Proc. 4 t h I n d . Waste Conf., Purdue Univ., 33, 45 (1948). (9) Porges, N., and Hoover, S. R., Ibid., 6th Conf., 34, 130 (1949).
(10) Porges, N., Pepinsky, J. B., Hendler, N. C., and Hoover, 8. R., Sewage and I n d . Wastes, 22, No. 3 , 318 (March 1950). (11) Ibid., 22, No. 7, 888 (July 1950). (12) Rhame, G. A., Water & Sewage Works, 94, 192 (1947). (13) Spaulding, R.A,, Proc. 4th 2nd. Waste Conf., Purdue ‘Univ., 33, No. 4,40 (1948). (14) Task Committee on Dairy Waste Disposal, Dairy Industry Committee, Milk Dealer, 39, No. 5, 88 (1950); 39, No. 6, 51 (1950); 39, No. 7, 47 (1950). (15) Trebler, H. A., Proc. I s t l n d . Waste Conf., Purdue Univ., 6 (1944). (16) Trebler, H. A., and Harding, H. G., IND. ENG.CHEM.,39, 608 (1947).
(17) Trebler, H. A., and Harding, H. G., Proc. 4th 2nd. Waste Conf., Purdue Univ., 33, 67 (1948). RECEIVED for review October 26, 1951.
AOCEPTBD January 19, 1952.
GRAIN DISTILLERIES C. S. BORUFF, HZram Walker & Sone, Inc., Peoria, Ill. Beverage distillers are recovering, drying, and marketing their destarched grain stillage as distillers dried grains and dried solubles. Some stillage is being refermented to give riboflavin and Blz feed supplements which play an important role as supplements in balancing poultry and livestock rations. Distillers dried solubles also serve commercially as a yeast growth supplement and in the production
of fungal amylase and streptomycin. Under good housekeeping practices and complete stillage recovery as feeds, the industrial waste load from a grain diaillery will possess a population equivalent of 1.0 to 3.5 per bushel of grain ground, Intraplant studies have identified the source of these wastes. High rate trickling filters or anaerobicdigestion may be used to stabilize the waste where necessary.
ASTES from U. S.graindistillerieshave been progressively and materially reduced since the repeal of prohibition in 1933. Team research and development in the fields of chemistry, chemical engineering, biochemistry, nutrition, and marketing, along with capital investments, have taken grain distillers “slop” out of the category of a waste and converted it t o important byproducts, Even its name has been changed-namely, from slop t o stillage. Products now recovered or produced from stillage have become profitable items of commerce for t h e distillers. A 1949 survey by the Distillers Feed Research Council, Inc., shows t h a t 85% of all grain beverage distillers’ stillage is now being dried and sold as feeds, 14% is fed wet, and only 1% is wasted.
only few evaporators were used in preprohibition days t o concentrate the thin stillage-liquid that passes through the screenstoday most beverage distillers evaporate these solubles t o a 25 t o 40% solids sirup and dry them with their screened grains t o produce distillers dried grains containing solubles (dark grains). A number of distillers drum-dry part of their evaporated solubles t o produce distillers dried solubles. This latter product was the result of post-repeal research and was first placed on the market in 1939. A large number of distillers now produce both dried grains containing solubles and dried solubles (see Figure 1). The history and more complete descriptions of the various processes employed in processing grain t o whisky and alcohol and the recovery of the above three distillers feeds have been published elsewhere (1, 4, 7, 9-11, $2, 93). The effect of using various grains and manufacturing processes on the chemical and vitamin content of distillers feeds has also been reported (1-4, 19,dO, 99,$3). T h e role of these products in producing balanced poultry and livestock rations has been covered in a number of publications of the Distillers Feed Research Council, Inc., Cincinnati, Ohio, and elsewhere (1, 19, 20, $9,$3).
Recovery of Stillage I n brief, the processing of grain to alcohol, carbon dioxide, and distillers feeds involves the milling and cooking of the grain, converting t h e solubilized starch to grain sugars by adding malt, fermenting with yeast, and then distilling off the alcohol or whisky (see Figure 1). T h e carbon dioxide developed during t h e fermentation is recovered in some of the larger plants and converted to dry ice. T h e de-alcoholized fermented mash from t h e stills (called stillage) contains from 5 t o 7% solids, possesses a biochemical oxygen demand of around 25,000 p.p.m., a p H of 3.6 t o 4.0, and amounts t o about 40 gallons per bushel of grain mashed. The 17 t o 19 pounds of solids contained in the stillage produced from one bushel of grain are about half suspended and half dissolved. Commercial screens of various designs will separate 8 t o 9 pounds of these solids. When dried in rotary steam dryers these screenable solids become distillers dried grains, a product known in the trade as light distillers grains. Although
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Special Uses for Distillers Solables Grain distillers screened stillage (2.5 t o 3% solids) and distillers dried solubles have, within the past few years, been found t o be excellent media for a number of biological processes. I t s high soluble protein and vitamin content was first utilized as a yeast supplement by various distillers. The production of a malt replacement enzyme concentrate, fungal amylase, has been reported and used t o a limited extent commercially ($6). Dried distillers solubles are also being used in the media for commercial antibiotic production, mainly streptomycin (16, 1 7 ) . The pres-
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491
Liquid Industrial Wastesaddition t o the accidental and shut-down and clean-up grain processing, fermenting, distilling, and feed recovery losses, there are certain normal wastes from the unit processes which contribute to the plant pollution load. Tail waters from the evaporators, containing some carry-over and volatile acids, along with !Trashings from recovery equipment, constitute more than one half the pollution load from a medium t o large distillery practicing complete stillage recovery. Whereas the data in Table I show a population equivalent load of 3010 per thousand bushels of grain processed, two other surveys report 3500 (87) and 2350 (14). Another survey, where evaporator tailings and cooling waters are spray tower cooled and largely recirculated, reports figures as low as 1080 per thousand bushels mashed. Differences in final pollution load data from different distilleries would be expected because of differences in operating practices, programs, and types of equipment used. Variations such as the grain mixture used, atmospheric cooking compared with pressure cooking of the grains, ratio of quantity of whisky t o quantity of spirits produced, types of spirit stills used, whether double-pipe coolers or vacuum-type coolers are used, types of evaporators and types of dust collectors used-all will materially affect the quantity of solids lost, the volume, the biochemical oxygen demand potency, and the population equivalent of the waste. The fact that this companyuses water sprays in the final stage of its dust collection adds a pollution load t o the liquid wastes by removing same from the discharged air. Pattee (18) and Davidson (11) have discussed the effect of evaporator design and operations upon stillage evaporator tailings. These authors ieport biochemical oxygen demand data ranging from 10 t o 3200 p.p.m., but found most samples t o run between 400 and 600 p.p.m. Hiram Walker evaporator tailings average 107 p.p.m. (Table I).
COURTESY ECHENLEY DISTILLERS, I N C
Jas.
E. Pepper & Co. Distillerj Waste Treatment Plant at Lexington, Ky.
ent authoi and colleagues have reported recently (6, $4) on the commercial production of a feed riboflavin (15,000 micrograms per gram) and vitamin B concentrate using A . yossypzz, and on a process for the production of a feed BI2concentrate containing an antibiotic, using screened stillage as the basic media. Distillers solubles and the refermented products referred t o above contain not only appreciable quantities of known B vitamins, but also other demonstrable, but as yet unidentified, growth, reproduction, and lactation factors (6, IS, $4).
GRMN,
MALT
Market for Distillers Feeds The market developed for each of the distillers feeds and the specialties mentioned above has been well established. Use has kept pace with production, except during exceptionally high production periods.
Pollution Load from Grain Distilleries For some years the technical division of Hiram Walker & Sons, Inc., has been studying the pollution load from various departments of its distilleries. The stillage from any distillery accounts for the greatest potential pollution load. With its recovery as distillers feeds and its partial biochemical conversion t o other valuable products, the study of distillers r a s t e s has been shifted from stillage t o the losses and wastes from various unit processes. The data given in Table I show the source, solids content, and 5-day biochemical oxygen demand of processing wastes. These detailed source of waste data, collected by the use of proportioning automatic samplers, check well ( f 5 % ) with sepver outfall data collected periodically over a n extended number of days (never less than 1 week). Standard methods (86) of analysis nere used throughout. It was found necessary t o prepare the biochemical oxygen demand dilution water outside the laboratory because the laboratory air contained alcohol vapors which possess biochemical oxygen demand. With no stillage recovery the population equivalent of a distillery will run about 50,000 per 1000 bushels of grain mashed. With screened stillage recovery only (recovery of dried grains only) the population equivalent is reduced t o around 30,000. With complete stillage recovery, the pollution load is reduced t o 2500 to 3500. As the waste and gallonage data in Table I are studied by one experienced in t h e field, i t is realized that there is a certain practical ceiling on intraplant recovery which is short of 100%. I n 492
I
WHOLE STILLAGE
CEREAL PRODUCTS
Figure 1.
'
Simplified Flow Diagram of Distiller) Operations
Water usage and hence plant waste volume (if all cooling water is combined with wastes as a t the Hiram Walker plant) will also vary widely, depending upon equipment, temperature of water used, extent of water recycling, and other normal manufacturing variables (11, 21). The figure of 711,407 gallons of waste and condenser waters per thousand bushels of grain processed given in Table I is high compared with most distilleries. This iu due to the fact that Hiram Walker uses river water, which during the summer months reaches 85" F., for processing, cooling, and collecting ash and fly ash, removing dust and fumes from the final stage of distillers feeds dust collectors, and a flash cooler for cooling its mashes (21). Data given in Table I are characteristic of near-capacity &day mashing and distilling operations, processing mainly corn. They also include week-end clean-up operations which have been charged against the quantity of grain used during , the &day mashing-distilling schedule.
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-Liquid Treatment of Wastes from a Distillery Practicing Complete Feed Recovery
Table I.
Industrial Wastes
Sources of Pollution Load from Modern Distillery Practicing Complete Stillage Recoverya Total
Population
Biochemical Oxygen Demand Equivalent Solids, Volume Many large distilleries are located on per 1000 Gal./ l O O b Lb./1000 Lb./1000] % of Source Bushels large enough waterways so that their Bushels Bushels P.p.m . bushels total Cooking and fermenting wastes from the distillery and complete 22.4 124 Pressure cooker blowdown 3,671 11.5 0.7 3.8 feed recovery plant can be disposed of Cooker blow vent stack drippings 24 0.02 0.6 0.7 500 0.1 without difficulties. However, some Cooker vacuum aspirator trap 16,941 0.6 18.8 7.0 23 3.2 distilleries are not so situated. There222.3 263,428 7.4 Flash cooler (81) 35.5 17 37.8 Flash cooler cleanup 31.2 1.0 314 9.2 5.3 2,025 fore, they must practice uneconomic reFermenter cleanup 70.0 2.3 3.2 11.9 421 3,388 Yeast tub cleanuo 847 5.3 1 . 3 0 . 2 _. 0 . 9 128 coveries within their plants and then Total, cooking and fermenting 288,613 12.2 370.6 68.4 26 63.0 etabilize their final wastes. Inasmuch as Distilling t h e effluent from a distillery and a comHigh wines water 38.8 3,097 1.6 256 6.6 1.3 Fusel oil wash water 13.0 3 0.8 89,000 2.2 0.4 plete feed recovery plant is a high-volume Slop tester drain 3.5 48 1.4 1,500 0.6 0.1 waste, with a major portion of the pollu55.3 Total, distilling 3,148 3.8 9.4 1.8 358 tion carried in a completely dissolved Feed recoverv olant Hot well f r o 6 triple evaporators form, effective treatment is costly. (tail waters) 1,328 2 254,118 225 8 41.1 147.5 107 Hot well from finishing pan High rate trickling filter treatment condensers 84,706 6.2 187 6 17.5 31.9 45 plants are in operation in four small Fume chamber scrubber trap for vapors from drum dryers 342.4 18.6 25,412 11.4 275 58.2 plants. Davidson (11) has reported t h a t Dust collector for dried grains dryersb at these plants a biochemical oxygen de602.9 147.2 1,137 102.5 20.0 10,818 Scrubber trap for cyclone on mand reduction of 93% is accomplished dried grains cooling system 12 3 1.2 8,706 2.1 0.4 29 Scrubber trap for dried solubles with filter loading rates of eight million airveyor cyclone 1.2 536 0.04 0.8 45 0.2 gallons per acre per d a y (6-foot filters Equipment cleanup 35.3 380 110.0 1.2 2,057 6.0 Total, feed recovery plant 884,646 2,509.9 442.8 83.3 426.7 1,331 with a 4 t o 1 recirculation rate) and 0.75 Power house (powdered ooal wet pound biochemical oxygen demand per ash, and fly ash recovery$ cubic yard. Activated sludge treatment 72.9 Total, power house 35,000 1,500 12.4 2.4 43 was not found satisfactory. Anaerobic 3008.7 Grand total 711,407 2,015 511.5 99.7 86 treatment of this same distillery effluent a Data based on Hiram Walker & Sons, Inc., Edmund St. Plant, PForia, Ill., operating a t 100,000 bushels/d-day week, mainly corn, including 7th day clean-up operations. Domestic wastes to city has been investigated on a laboratory sanitary sewer. Well water (20% total) used in product processing: river water, 32q to 85O F.. 80% of total used for all other purposes. Biochemical oxygen demand data corrected for biochemical oxygen scale, using 5-gallon continuous digesters dernknd of river water where used. equipped with mixers. Biochemical oxyb Recovery equipment being installed, gen demand reductions as high as 96 t o 98% during a 24hour retention period were obtained (12). I n 1932 Boruff and (6) Boruff, C. S., and Buswell, A. M., IND.ENG. CHEM.,24, 33 Buswell (6)reported successful studies on the 2- t o &day thermo(1932). philic anaerobic digestion of concentrated stillage. Even better (7) Boruff, C. S., and Weiner, L. P., Trans. A m . Inst. Chem. Engrs., results should now be accomplished using these authors’ volatile 33, No. 1, 84 (1937). acid control process (8). For a number of years t h e Peoria ( 8 ) Buswell, A. M., and Boruff, C. S., U. S.Patent 2,029,702 (Feb. 4, 1936). Sanitary District has digested, and further treated by activated (9) Chem. & Met. Eng., 52, 130 (1945). sludge, some molasses and grain stillage with sanitary wastes (15). (10) Cooley, L. C., IND.ENQ.CHEM.,30, 615 (1938). (11) Davidson. A. B.. Sewage and Ind. Wastes. 22. 654 (1950). Summary (12) Davidson, A. B.;and Banks, J. F., Proc. 4th Ind. Waste Utilization Conf., No. 68, 94 (1949). Stillage is the most potent of all potential distillery wastes of (13) Hill, F. W., Scott, M. L., Norris, L. C.. and Heuser, G. F., significant volume; it has a biochemical oxygen demand of Poultry Sci., 23, 253 (1944). (14) Kolachov, P. J. (Jos. E. Seagram & Sons, Inc.), private comaround 25,000 p.p.m. munication, March 13, 1951. Eighty-five per cent of the stillage from beverage distilleries (15) Kraus, L. S., Sewage Works J., 5, 627 (1933). in the United States is now recovered as dried feeds, 14% is fed (16) McDaniel, L. E., U. S. Patents 2,538,942 and 2,538,943 (Jan. 23, wet, and only 1% is wasted. 1951). Stillage recovery as feeds reduces the population equivalent (17) Nelson, H. A., Calhoun, K. M., and Colingsworth, D. R., 118th Meeting AM. CHEM.SOC., Chicago, Ill., 1950. from a potential of 50 per bushel of grain used t o 1.0 t o 3.5 per (18) Pattee, E. C., Proc. 4th Xnd. Waste Utilization Conf., No. 68, 122 bushel, depending on operating practices, programs, and types of (1949). equipment used. (19) Rasmussen, R. A., Chemurgic Digest, 8, No. 1, 8 (1949). Final wastes from a modern distillery and complete feed re(20) Rasmussen, R. A., Smiley, K. L., Anderson, J. G., Van Lanen, covery plant are high-volume wastes and, where disposal by diJ. M., Williams, W. L., and Snell, E. E., Proc. SOC.Ezptl. Biol. Med., 73, 658 (1950). lution t o bodies of water is not possible, are being treated sepa(21) Rodgers, C. H., Chem. Eng., 5 5 , 122 (1948). rately and effectively on trickling filters. Stabilization by (22) Schaible, P. J., Chemurgic Digest, 9, No. 4, 69 (1950). anaerobic digestion is also possible. (23) Schaible, P. J., Feedstugs, 21, No. 46, 20 (1949). (24) Smiley, K. L., Sobolov, M., Austin, F. L., Rasmussen, R. A., Literatare Cited Smith, M. B., Van Lanen, J. M., Stone, Leonard, and Boruff, C. S., IND.ENG.CHEM.,43, 1380 (1951). (1) Bauernfeind, J. C., and Boruff, C. S., Am. MzZZer, 72, No. 1, 182; (25) “Standard Methods for the Examination of Water and Sewage,” No. 2, 53; No. 3, 50 (1944). 9th ed., New York, American Public Health Assoc., 1946. (2) Bauernfeind, J . C., Smith, M. B., Garey, J. C., Baumgarten, (26) U. S. Dept. Agri., Tech. Bull. 1024 (August 1950). W., Gustoff, F. H., and Stone, Leonard, Cereal Chem., 21, 421 (27) U. S. Public Health Service, Rept. Ohio River Pollution Control, (1944). 78th Congress, House Document No. 266, Appendix VI, (3) Baumgarten, W., Stone, Leonard, and Boruff, C. S., Ibid., 22, Supplement D, 1126 (1944). 311 (1945). (4) Boruff, C. S.,IND.ENG.CHEW,39, 602 (1947). (5) Boruff, C. S., Proc. 6th Conf. Feeds Beverage Inds., 41 (1951). RECEIVED for review October 15, 1951. ACCEPTED January 14. 1RS2.
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