Anoxic/Oxic Activated Sludge Treatment Kinetics of Cyanides and Phenols

Abstract

The anoxic/oxic activated sludge treatment kinetics of cyanides (i.e., cyanide and thiocyanate) and phenols (i.e., phenol, cresols, and catechol) are studied. The Michaelis‐Menten expression or its simplified forms are used to model the following microbial reactions associated with the process: (1) Anoxic/oxic TOC utilization; (2) anoxic denitrification; (3) nitrification; and (4) cyanide and thiocyanate utilization. The steady‐state experimentation is performed to obtain experimental data for the validation of kinetic models and evaluation of kinetic coefficients. The results obtained indicate that all oxic microbial reactions occurring in an anoxic/oxic activated sludge process are not affected kinetically by the presence of the anoxic environment with high oxygen stress. As a result, the results collected from both conventional and anoxic/oxic activated sludge units exhibit identical kinetic patterns. Anoxic TOC utilization, anoxic denitrification, and nitrification reactions are describable by zero‐order expressions; oxic TOC utilization by first‐order expressions; and cyanide and thiocyanate utilization rates by Michaelis‐Menten expressions. The TOC requirements for denitrification including cell synthesis is approximately