The dynamics and control of substrate inhibition in activated sludge∗

Abstract
The activated sludge process is one of the most widely used biological methods of waste‐water treatment in the chemical and steel industries. Evidence indicates it can be used to remove many organics toxic or inhibitory to the microbes employed in the process. A variety of removal mechanisms are involved, but the predominant one for nonvolatile compounds is biodegradation. The kinetics of this degradation and the mechanism by which these compounds inhibit the sludge are poorly understood. Existing theory suggests that operational difficulties associated with inhibitory wastes arise due to process dynamics. This article reviews the dynamics and control of activated sludge systems treating inhibitory wastes, with the objective of elucidating areas in need of further research.