April 1950
INDUSTRIAL AND ENGINEERING CHEMISTRY BIBLIOGRAPHY
(1) Barry, E. F., and Gaddie, R. S., Proc. Am. SOC.Sugar Beet Technol., 1948, pp. 674-80. (2) Diokinson, B. N., Chem. Eng., 55, No. 7, 114 (1948). (3) ~ l l iH.~E., ~ presented ~ , before the ~ i ~of sugar i ~Chemistry, i ~ ~ 115th Meeting of the AMERICAN CHEMICAL SOCIETY,San Francisco, Calif. (4) Ellison, H. E.,Proc. Am. SOC.Sugar Beet Technol., 1948, pp. 557-62. (5) Fitch, E. B., and Michener, J. W., Ibid., 1948,pp. 696-704. (6) Haagensen, A. E., Ibid., 1948,pp. 690-5. (7) Haagensen, A. E.,Sugar, 41,36 (1946). (8) Jacobs, R. T., and Rawlings, F. N., IND. ENQ. CHEM.,41, 2769-75 (1949).
647
(9) Maudru, J. E.,Proc. Am. SOC.Sugar Beet Technol., 1947, pp. 161-7 1. (10) Nees, A. R.,and Bennett, A. N. (to Great Western Sugar), U. S. Patent 2,375,165(May 1, 1945). L.s.,prOc.Am. SugarBeetTechnol., 1948,PP. 714-21. (11) (12)Rawlings, F. N.,Jacobs, R. T., and Cole, E. B., 7th Intern. Congress Agric. Ind., Paris, France (May 1948). (13) Thompson, R. B., and Roberts, E. J., Chem. Eng. Progress, 43, No. 3,97(1947). (14)Vallez, A. H.,U. S. Patept 2,388,194(Oct. 30,1945). RECEIVED August 9, 1948. Presented as a part of the Symposium on Ion Exchange Application before the Division of Water, Sewage, and Sanitation CHEMICAL SOCIETY, Chicago, 111. Chemistry, 113th Meeting of the AMERICAN Revised 1949 to include data. from 1948-1949 campaign.
*
Treatment of Rice Water
n
CHARACTERISTICS AND LABORATORY STUDY HOVNANESS HEUKELEKIAN New Jersey Agricultural Experiment Station, Rutgers, N . J .
T h e waste water produced from the preparation of Minute Rice is carbonaceous and deficient in nitrogen. The solids are i n finely divided, i n colloidal, and in soluble forms. The average B.O.D. of the composite waste is around 1000 to 1100 p.p.m. with wide variations. Laboratory tests show that plain sedimentation results in only 30% B.O.D. reduction with accompanying large volumes of sludge. Lime treatment of settled liquor (1000 to 4000 p.p.m.) produced a n additional 15 to 40% B.O.D. removal. The anaerobic digestion of the raw rice water gave consistently satisfactory results. With B.O.D. loadings of 0.1 pound per cubic foot digestion capacity per day and a detention time as low as 1.2 days, a B.O.D. reduction of 92% was obtained. Without lime neutralization and with only small amounts of ammonia added for nutritional purposes, the efficiencies were as high as with neutralization, but the loadings were lower. The aeration of the raw waste with suitable seed material for 24 hours and sufficient quantities of nitrogen for nutritional purposes produced an effluent with 25 to 50 p.p.m. B.O.D. and reductions of more than 90%.
are 35 to 1. These ratios indicate that for biological treatment the nitrogen content is somewhat inadequate and has to be supplemented, whereas the phosphorus content is ample. The waste contained 1200 p.p.m. of starch and 70 p.p.m. of reducing sugars. On the basis of 0.6 to 0.7 part of 5-day B.O.D. for each part of starch and sugar, these two ingredients alone ahcount for 70 t o 80% of the total B.O.D. Five hundred and thirty pounds of B.O.D. and 730 pounds of solids are produced per ton of raw rice handled.
TABLE I. CHARACTERISTICS OF COMPOSITE RICEWASTE 4.2-7.0 1460 20.6 610 10.8 30 30
PH Total solids p.p.m. % Suspended Ash in totafsolids, solids, p.p.m. Ash in suspended solids Yo Total nitrogen (N), p.p:m. Phosphates (PI, p.p.m. B.O.D.. o.u.m. Starch,'p.p.m. Reducing sugars, p.p.m.
1 ne5 . ___
1200 70
TREATMENT OF WASTE BY SEDIMENTATION
I
N T H E preparation of Minute Rice large volumes of wastes
are produced from soaking, cooking, and washing processes. The volumes of waste produced from the different processes are: Soaker Cooker Drain belt Drain tank Total
Gal./Ton 8,400 8,400 24,000 20,000 60,800
On the basis of 30 tons of raw rice handled per day, the total waste volume is about 1,800,000gallons. CHARACTERISTICS OF WASTE
The average analyses of a number of composite samples are given in Table I. The p H values, which varied from 4.2 t o 7.0, are affected by changes during shipment of samples. The total solids were 1460 p.p.m. and the ash in the solids was 20.5%. The suspended solids were 610 p.p.m. with an ash content of 10.8%. The waste had a nitrogen and phosphorus content of 30 p.p.m. each. The average B.O.D. of 20 samples was 1065 p.p.m., with a minimum of 400 p.p.m. and a maximum of 1590 p.p.m. The B.0.D.-nitrogen and B.0.D.-phosphorus ratioa
Plain sedimentation gave the following results:
a
Total solids Suspended solids B.O.D. 1-hour sedimentation.
Before Settling, P.P.M.
Aftera Settling, P.P.M.
Reduction,
1816 753 1380
1446 31 979
20.5 96 29
%
The rather low removal of B.O.D., despite the high removal of suspended solids, indicates that most of the B.O.D. is in the form of colloidal and soluble materials. This is substantiated by filtration of the waste through a Gooch filter, which gave a removal of only 25% of B.O.D. The sludge formed by sedimentation was thin and variable in volume, averaging 13.0% of the total volume of waste. I n view of the low B.O.D. removals and high sludge volumes, plain sedimentation is not a suitable method of treatment. L I M E TREATMENT
Settled composite waste was treated with various quantities of lime, stirred gently for 20 minutes, and allowed t o settle. The average results of four tests were:
INDUSTRIAL AND ENGINEERING CHEMISTRY
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TABLE 11. DIGESTION O F RICE Detention NHaOHb Lime Time, Added, Added, Period Days % Days G./L. G./L. pH I 15 50 3 0 0 59 0 6 8 100 2 0 0.39 0 6.6 150 1 7 0.35 0 6.5 1.5 0.33 0 6.5 200 I1 3 50 2.0 '0.60 0 7.1 1.5 0.37 0 6.7 100 150 1.3 0.35 0 6.7 200 1.2 0.37 0 6.7 111 20 50 3.0 0.07 0.93 6.6 100 2.0 0.07 0.93 6.6 6.6 150 1.7 0.07 0.93 200 1.5 0.07 0.93 6.5 0 6.3 2.0 0.04 IV 16 100 0 6.3 23 150 1.7 0.04 0 6.2 1.5 0.04 23 200 8 400 1.2 0.04 0 6.1 0 % b y volume of daily additions in relation to sludge volume. h Expressed as 100% NH4OH.
WATER
Volumetric" Dosing,
TABLE111.
-4ERATIOS O F SETTLED
Do'ings
Type Seeding Of
Ratio of Waste to Seed
0
Settled liquor Settled liquor Sludge Settled liquor Settled liquor Settled liouor Sludge Sludge Sludge
5: 1 3.4:1 3.4:l 1 4 . 5 :1 14.5:1 14.5:l 14.5:l 14.2:1 14.5:l
s o . of
6 6
to
10 10 10 10
10
Lime, p.p.m. B.O.D., 9.p.m. B.O.D. reduction, % Sludge volume, %
0 815
...
6.2
Ran, p.p.m.
1080 1080 1080 1080 1290 1290 1290 1290 1370 1370 1370 1370 705 745 745 818
RICEW.4TER
B.O.D. B.O.D. Raw Treated Reducwaste, waste, tion,
p.p.m.
p.9.m.
%
N Added, P.P.M.
1044 877 877 640 640 640 640 640 640
131 346 215 20 26 55 24 17 21
87 60 75 97 96 91 96 97 96
9 0 0 48 24 12 48 24 12
3000 625 35 20.5
4000 495 39 20.5
1000 690 15 20.4
2000 570 30 22.4
The optimum dosage of lime was 2000 p.p,m., producing a n additional removal of 30% B.O.D. over plain sedimentation, or a total of 60% removal on the basis of the nonsettled waste. The sludge volumes produced by lime treatment were high, but, vacuum filtration of the lime sludge without additional chemicals was feasible. Optimum filtration rates were obtained with waste treated with 4000 p.p.m. of lime. DIGESTION OF RICE WATER
The nonsettled composite rice water was digested a t 30" C' b y daily feeding to acclimatized digested sewage sludge, and t h e digested liquor was withdrawn and replaced daily with an equal volume of waste. The experiment was run for 3 months under various conditions. The average results are given in Table 11. During the first period the daily additions were such that the theoretical displacement time varied from 3 t o 1.5 days. Ammonia was used both as a source of nitrogen and as neutralizing agent. The B.O.D. of the supernatant liquor increased from 58 p.p.m. with the lowest dosing t o 170 with the highest, and reductions decreased from 95 to 84%. The loadings varied from 0.023 t o 0.045 pound of B.O.D. per cubic foot per day. I n the second period the loadings were increased by feeding the digesters twice a day, thereby reducing the theoretical displacement time from a maximum of 2.0 t o a minimum of 1.2 days. With a stronger raw waste fed and consequently higher loading (0.05 t o 0.1 pound per cubic foot per day) the B.O.D. of the effluent did not deteriorate with increasing loadings and decreasing detention time as in the first period. -4loading of 0.1 pound per cubic foot per day is equal to 2.7 pounds per cubic yard per day, which is higher than the usual 1.5 pounds of B.O.D. per cubic yard applied to high-rate filters. The B.O.D. reductions obtained by such loadings to high-rate filters are not in excess of 85%, which is lower than those obtained in these experiments with higher loadings by digestion.
Vol. 42, No. 4
I n the next period the feed ings were made once a day and consequently the volumetLoading, UIJieducLb./ r i c d e t e n t i o n p e r i o d was gested, tion. Cu. Foot) longer and the B.O.D. loading p.p.m. c/o Day 58 95 0 023 was lower. The object of this 66 95 0.034 experiment was to determine 112 89 0 040 170 84 0,045 whether lime could be sub78 94 0,051 stituted for ammonia for neu72 94 0.080 87 93 0,097 t r a l i z a t i o n . Only sufficient 104 92 0.107 ammonia was fed daily t o meet 50 96 0.028 the nutritional requirements. 40 97 0,043 45 97 0,050 I n comparison with the first R7 96 0.057 period, the B.O.D. of the suprr44 93 0.022 44 94 0.028 natant liquor was even lower. 48 94 0,031 In the last series of test* 61 93 0.045 lime was omitted and only enough ammonia mas used for nutritional purposes. Dosings were made once a day. The B.O.D. of the rice water fed was lower than in previous tests and consequently the loadings were low, despite the high volumetric dosages used. The pH value of the digesting mixture was lower than in any of the previous series, but despite this the B.O.D. values of the supernatant liquor mere as low as in any of the previous series where pH values were maintained a t a higher level with lime or ammonia, The reported B.O.D. values of the supernatant are the averages; however, during the sufficiently long period the B.O.D. values did not show a tendency t o increase. The one exception to this was the last. test in period IT' with 400% volumetric dosing, when on the eighth day of dosing the B.O.D. of the supernatant increased from an initial of 58 to 140 p.p.m. I t appears that without neut,ralizationthe loadings cannot be as high as with neutralization. The quantities of ammonia fed for nutrit.iona1 purposes only were adequate, as indicated by tests of the residual ammonia in the supernatant liquor. The minimum amount of nitrogen t o be added was not determined. Over a long period there will be some sludge accumulation, but the actual quantities cannot tip determined from laboratory st,udies. AERATION OF SETTLED RICE WATER WITH BIOLOGICAL GROWTHS
The settled rice water was aerated for 24 hours with biological growths produced. The initial inoculum was made with sewage. Aft,er the seed was developed, a port'ion of the aerated material was ret,ained as seed, and daily dosages of settled rice wat,er were made. The volume of seed used in relation t,o waste t o be treated was varied. I n certain tests the seed material consisted of sludge-free aerated liquor, and in others the sludge formed from the aeration process was used. The effect, of the addition of nitrogen on the efficiency of the process was studied. The results summarized in Table I11 show that nitrogen addition is an important factor. The B.O.D. of the effluent was high with inadequate or no nitrogen additions, whether sludge or settled liquor was used for seeding. The seeding ratio was also high in this series. The addition of 12 to 24 p.p.m. of nitrogen is required to give optimum results. The waste itself cont,ains 30 p.p.m. of total nitrogen, part of which is also available for assimilation by the organisms. The results further indicate t h a t it makes lit'tle difference whether sludge or settled aerated liquor is used for seeding. With a waste t o seed rat,io of 14.5 t o 1 and with adequate nitrogen addition, more than 90% B.O.D. reduction was obtained. RECEIVED October 16, 1949. Presented before the Division of Water, Sewage, and Sanitation Chemistry a t the 116th Meeting of the AMERICAS CHEKICAL SOCIETY, Atlantic City, N. J. Paper @f the Journal Series, Kew Jersey Agricultural Experiment Station, Rutgers University, State University of New Jersey, Department of Sanitation.
