Vol. 22, No. 3
INDUSTRIAL AND ENGINEERING CHEMISTRY
276
water-soluble carbohydrates, while they are low in watersoluble phosphorus and starch and high in nitrate nitrogen. The nitrogen-deficient plants, on the other hand, are lower in total nitrogen and the different forms of water-soluble nitrogen and higher in water-soluble phosphorus and starch, and contain no nitrate nitrogen. Relatively simple tests, such as the diphenylamine test for nitrate nitrogen and the iodine test for starch, together with observations of the appearances of the plants, should be of value in detecting phosphorus or nitrogen deficiency. The extent to which these relationships will hold for other plants is of course uncertain. Hoffer has applied similar tests to the corn plant and there is evidence that they may be applied with success to other plants. I n the case of woody plants, such as the apple, however, we have a different situation. Both Eckerson and Thomas have s h o r n that nitrate nitrogen is seldom found in the above-ground portions of the apple tree. I n this case nitrate reduction seems to occur almost entirely in the small roots. Applications
Recently in the field of horticulture increased attention has been given to the use of plant metabolism studies in determining fertilizer as well as other cultural practices. As a result of such studies the recommendations regarding the use of fertilizer, use of cover crops, method of pruning, etc., have been placed upon a much more rational basis. Many of the apparently conflicting results of field experiments when analyzed from this standpoint have been explained. Hoffer (3)has recently made application of the use of chenii-
ea1 tests on corn plants as an aid in determining their fertilizer requirements. By using the results of the diphenylamine test for nitrates together with the appearance of the plants he is able to detect deficiencies in nitrogen or phosphorus within the plant. He has also found marked accumulation of iron in the internodes of the plants in cases of potassium deficiency which may be detected by the thiocyanate tests. Furt’her studies to determine the extent to which these tests may be applied to other plants and the conditions which cause iron accumulation are much needed. Gilbert and Hardin (1) have studied the relation of nitrogen, phosphorus, and potassium in the juice extracted from plants to the fertilizer treatments which have been applied, and believe that such studies will be of help in determining the fertilizer requirements of plants. From the writer’s studies of phosphorus- and nitrogendeficient tomato plants it seems that there is good promise in this method of attack. Nitrogen-deficiency in the tomato plant can be detected readily by the restricted growth, pale green color of the plants, and the absence of nitrate nitrogen in the plants. Plants deficient in phosphorus, on the other hand, show a similar restricted growth but are deep green in color, frequently show a purplish tinge, contain an abundance of nitrate nitrogen, and are low in water-soluble phosphorus. Literature Cited (1) Gilbert and Hardin, J . Agr. Research, 36, 185 (1927). (2) Hepler and Kraybill, N. H . Agr. Expt. Sta., Tech. Bull. 28 (1925). (3) Hoffer, Purdue University Agr. Expt. Sta., Bull. 298 (1026). (4) Kraybill and Smith, N. H. 4gr. Expt. Sta., -4nnual Rept., Bull. 812, 8 (1924).
Some Observations on Beer-Slop Waste from Corn-Mash Distillation’ W. D. Hatfield SANITARY DISTRICT OF
HE digestion of sewage solids, in two-story Imhoff tanks, in separate sludge-digestion compartments, by aera-
T
tion, or by sprinkling filter, is easily disturbed by a change in the acidity of the medium or the introduction of organic matter which may change the character of the fermentations and oxidations taking place in the processes. The study presented in this paper was undertaken to determine the probable effect on sewage-disposal processes of the “beer slop” resulting from the operation of a large butanol manufacturing plant in Peoria, Ill. This work was done in conjunction with the engineer’s preliminary work on the design of a sewage-treatment plant for Peoria. In this process for the manufacture of butanol and other solvents about 20,000 bushels of corn a day are ground and cooked to a fine mash, cooled, fermented with especially prepared cultures, and distilled. The distillate contains the valuable solvents and the residue is called “beer slop.” This residue amounts to over 1.25 million gallons per day. Analysis of Beer-Slop Waste
L)BCATUR,
ILL.
corn grits in a grit chamber, but the floc in the waste settles very slowly and is so light that its settling would be easily disturbed by stray currents in a settling tank. Settling experiments showed that in 1 hour a light fluffy sludge settled to about 40 per cent of the total volume, in 2 hours to 30 per cent, and in 11 hours to 22 per cent. Neutralization of the acidity with hydrated lime in quantities of from 1 to 250 grains per gallon did not increase the settlability of the suspended matter. Neutralization of the alkalinity with sulfuric acid gave a clearer supernatant liquor but did not decrease the volume of sludge. of Beer-Slop Waste PERCENT CRUDEWASTE SETTLED WAS* REMOVEO
Table I-Analysis Suspended matter: Total Volatile Per cent volatile Total solids Total volatile solids: Per cent volatile Settlable solids (2 hours), cc. per 1000
4172 p. 4080 p. 98 11,196 p. 10,040 P. - 90.0
p. m. p. m. p. m.
P. m . -
2 grits, 400 floc P. p . m. 5700 12.000
824 p. 796 p. 96.7 8624 p. 7110 P. 82.5
p. rn. p. m .
80.2
p. m. P. m.
23 29
80.5
. .. P . p. m. 4000 8500 325 8
Numerous samples of the beer slop have been analyzed and a typical analysis is given in Table I. The data on suspended matter and total solids indicate the highly organic character of the materials in suspension and solution. The settlable solids suggest the possible removal of
Oxygen consumed (KMnOi) B. 0. D. (5-day, 20’ C . ) Total nitrogen (Kjeldahl) Ammonia nitrogen Acidity to phenolphthalein (as CaCOa) Alkalinity to methyl orange ( a s CaCOa) pH (colorimetric)
1 Received November 20, 1929. Presented before the Division of Water, Sewage, and Sanitation at the 78th Meeting of the American Chemical Society, Minneapolis, Minn., September 9 t o 13, 1929.
The acidity of the wast’es due to organic acids resulting from the fermentations is slightly less than 800 p. p. m. ex-
590 S
20.8
29.2 44.8 0
700
640- ( ?j 4.6 t o 0.0
INDUSTRIAL AND ENGINEERIXG CHEMISTRY
March, 1930
pressed as CaCO?, and the p H lies between 4.6 and 5.0. If this acidity needs to be neutralized with lime, as recommended by the British Royal Sewage Commission (2), it would take 3 to 4 tons per million gallons. Littlefield (2) has shown that distillery waste (pot ale) in England, after diluting 1 to 10 with other wastes and neutralizing with lime and settling, may he oxidized on trickling filters a t a rate of about 230,000 U. S. gallons per acre of stone (calculated a t depth of 6 feet).
277
Digestion of Sewage and Waste Solids In order to determine the effect of this highly organic sludge on the anaerobic sludge-digestion processes taking place in Imhoff tanks or separate sludge compartments, three digestion bottles of 1 quart capacity were set up with inlet, siphon, outlet, and gas delivery tubes. Well-digested lmhoff tank sludge mas used for the seeding sludge, the fresh sewage solids were 1 hour old, and the settled beer-slop waste was concentrated by 2-hour settling. The gas produced was measured over saturated sodium chloride solution, corrected to standard conditions, and analyzed occasionally. The pH of the sludge liquor was determined colorimetrically. The data on the experiments are given in Table I11 and Figure 1, and show that the beer-slop sludge was as easily digested as fresh sewage sludge under the conditions of the experiment. Analysis of the gas gave an arerage composition of 25 per cent carbon dioxide, 65 per cent methane, 0.8 per cent hydrogen, and 9 per cent nitrogen. Data ___I1 I
T a b l e 111-Sludge-Digestion
BOTTLES---
Grams Total solids. Digested sludge (inoculant) Fresh sewage sludge Beer slop sludge
Total volatile solids Total fresh volatile solids Ratio fresh volatile solids I 1 to 111, 1:1.93 Total gas corrected to standard conditions:
Figure 1
The oxygen consumed from permanganate and the 5-day €3.0.D. are near 6000 and 12,000 p. p. m., respectively. The indicated industrial population equivalent, calculated on a B. 0. D. basis, is greater than 800,000. Analyses of the liquor show a 30 per cent reduction in the oxygen consumed and B. 0. D. on quiescent settling. The total nitrogen is reduced about 45 per cent by quiescent settling. Settling Experiments on Beer-Slop Diluted with Sewage
Grams
38 0 0
38 0 3 5
--
__
38 0 3 5 1 95
38 0 0
41 5 3 5
43 45 545
10.6 0 0
-_
10.6 1.98 0
_-
10.6 1.98 1.85
10 6 0
12.58
14.43
0
Total solids Total fresh solids Volatile organic matter: Digested sludge (27.9 per cent volatile) Fresh sewage sludge (56.5 per cent volatile) Beer sloo - sludge - (94.7 oer cent volatile)
111
Grams
0
cc.
1.98
__
--_
cc.
342 557 5 days 941 1655 10 days 1439 2483 15 days 1724 2868 2 1 days 0 1144 Gas produced in excess of bottle I Ratio of gas produced by I1 t o 111, 1:l.S Gas per gram volatile organic matter added 578 (in 21 days) 6.8 6.8 pH of sludge liquor a t end of test Temperature of digestion varied from 17' to 28' C., averaging 1.9.5(b
3 83
cc. 600 2302 3246 3782 2058 547
6.8
c.
Conclusion
The beer-slop waste of the butanol fermentation plant is a dilute spent corn mash existing largely in solution and fine suspension. The oxygen demand indicates a population equivalent of 800,000 or more. On dilution of certain cornstarch factory wastes with sewage A sludge will settle in cylinders to about 40 per cent of the a floc is formed which settles readily in Imhoff tanks. This original liquid volume, but it is so light that it would cause fact suggested settling experiment's on the beer slop diluted trouble in settling tanks. On dilution with sewage the with sewage. Accordingly, samples of the hot waste were solids are easily settled out. The sludge is readily digested diluted with sewage and sedimentation tests made in seu-age- with sewage solids and produces the same quantity and settling cones. The settling data are recorded in Table 11. quality of gas as the organic matter from sewage. The high oxygen demand \\-ill greatly increase the amount T a b l e 11-Settling Mixtures of W a s t e a n d Sewage of sprinkling filter or activated sludge treatment necessary. sEW.4CE M I X T U R E W A 5 T E A N D SEWAGE WASTE Dilution" 0 1:13.3 1:lO 1:s 1 : 6 . 7 0 The cost of treating such a strong waste makes its recovery Temperature, C. 23 24.5 26.0 27.2 2 7 . 8 93 as a by-product within the industry necessary and advisable. Settlable matter: 1 hour, cc. per 1000 I 31 41 50 56 Studies of such recoveries are being made by the industry 2 hours, cc. per 1000 .> 27 38 45 52 42Q Calcd. 2-hour volume, concerned. cc. per 1000 ,5 36 46.5 57 67 420 Per cent less volume Acknowledgment 0 25 18 21 22 0 than calcd. a Dilutions represent the probable dry-weather dilution!, of the waste by Peoria sewage.
From the diluted waste the sludge settled readily t o a volume about 22 per cent' less than that calculated by adding the volumes of sewage sludge and waste sludge. This combined sludge should settle satisfactorily in settling tanks. The sludge of the undiluted waste is so fluffy that it would settle with difficulty in continuous-flow tanks without the aid of some coagulant other than lime or acid,
The writer wishes to acknovdedge the generous assistance given by S. A. Greeley and his assistants in the firm of Pearse Greeley and Hansen, for whom this work was done; and to his laboratory assistant Harold B. Staley, who assisted in the analyses. Literature Cited (1) Buswell and Neave, IXD.ENG.C H E M . , 20, 837 (1928). (2) Littlefield, J. SOC.Chem. I n d , 44, 860 (1925).
