Studies of Sewage Purification: XVII. The Utilization of Organic Substrates by Activated

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Abstract
This is a continuation of studies on the activated sludge process for sewage disposal. Expts. were conducted in a "closed-system aeration" tank. 36 organic compounds were studied, including a variety of sugars, alcohols, aldehydes, organic acids and amino acids. These compounds were added, individually, to activated sludge, as the sole source of energy, and O2 utilization detd. by the usual B.O.D. test. pH and sludge index were also noted. Although general conclusions have been drawn, based on the class of organic compound studied, certain significant variations were noted. Carbohydrates were oxidized to the least extent but produced the greatest amount of sludge. An exception is l-xylose which failed to promote growth of Sphaerotilus natans. Organic acids were most fully oxidized with lowest sludge production. Alcohols and amino acids were intermediate. Methyl alcohol, tyrosine and oxalic acid were not easily removed. Compounds containing SH, CHO and CN groups were detrimental to the sludge. Normal activated sludge rather quickly adjusted itself to changes in substrate material.