QUANTITATIVE ESTIMATION IN COD UNITS OF REFRACTORY ORGANIC-COMPOUNDS PRODUCED BY ACTIVATED-SLUDGE MICROORGANISMS

Data on the amounts of refractory organic compounds produced by activated sludge microorganisms under various conditions of cultivation were collected and treated to find the main factors influencing their production. The following systems were compared: batch nonproliferating and proliferating, continuous with high and low mean cell, residence time and semicontinuous with separate aerobic sludge stabilization. There was a linear relationship between the refractory microbial products and the initial substrate concentration, expressed in COD [chemical O2 demand]. The slope and intercept of the relationship depended on the mean cell residence time or the observed specific growth rate. Depending on the cultivation conditions, the refractory products amounted to 1-10% of the substrate consumed. The amount of refractory compounds expressed in COD U, released from 1 g of aerobically decomposed biomass varied from 15-25 mg/g.