The biological treatment of carbonization effluents—III: New advances in the biochemical oxidation of liquid wastes

Abstract

Biological treatment systems operating the continuous, completely mixed activated-sludge process have been employed to study the effect of the addition of certain biochemical factors such as p-aminobenzoic acid (PAB). This substance was found to act as an accelerating agent or growth factor on the nitrogenous constituents of certain wastes, when added to the influent at a concentration of only a few milligrams per litre. By using a solution of ammonium thiocyanate as the standard substrate, a number of such substances have been found, which can be classified into various groups and which have a significant effect on the rate of removal of constituents of coke-oven wastes such as thiocyanate and cyanide, which are normally the rate-limiting factors in coke-oven waste treatment. The results of the investigation illustrate a method of improving some biological oxidation processes, which may be adapted to full-scale treatment. It is believed that pyruvic acid plays a key role in the mechanism of the improved treatment process and experimental evidence has been found to support the hypothesis that an organic substance will behave as a growth factor if its aerobic degradation results in the formation of pyruvic acid, or some compound closely related to pyruvic acid in the biochemical sense. An example of the latter type of compound is glucose, the application of which to spent liquor treatment is economically attractive.