The effect of reactor hydraulics on the performance of activated sludge systems—II. The formation of microbial products

Abstract

A new model involving the concept of soluble residual microbial products formation was used to investigate the effect of reactor hydraulics on the substrate removal efficiencies of activated sludge systems. Strong experimental evidence in the literature suggests that what is measured in most studies is not the remaining portion of the influent degradable substrate, but organic matter of microbial origin which is residual, at least for the operating conditions considered. An appropriate simulation approach was formulated to account for the formation of these products, by a simple mechanistic modification of the newly proposed task group model. This model showed no practical difference between the performances of completely mixed and plug flow activated sludge systems, because they produced almost equal amounts of these microbial products, under similar operating conditions.