Unified Basis for Biological Treatment Design and Operation

TLDR

A unified basis for designing and operating biological waste treatment systems using microbial suspensions is developed from kinetic concepts and continuous culture theory. The authors introduce biological solids retention time (θc) as an independent design parameter, present steady‑state kinetic models for three reactor configurations, and use tabulated kinetic coefficients to compute minimum θc values for each process. Kinetic coefficients for aerobic carbonaceous treatment, aerobic nitrification, and anaerobic methanogenic fermentation are tabulated, and the resulting minimum θc values are compared with those of real treatment systems.

Abstract

A unified basis for design and operation of biological waste treatment systems employing suspensions of microorganisms is developed from microbial kinetic concepts and continuous culture of microorganisms theory. Biological solids retention time, θc, average time period a unit of biological mass is retained in the system, is suggested as an independent parameter for process design and control. Steady-state kinetic models are presented for three process configurations, i.e., completely mixed reactor without solids recycle, completely mixed reactor with solids recycle, and plug flow reactor with solids recycle. Reported values of kinetic coefficients are tabularized for: (1) aerobic treatment of carbonaceous wastes; (2) aerobic biological nitrification; (3) anaerobic methanogenic fermentation of carbonaceous wastes. These coefficient values are substituted into the models to determine lower limits, i.e., minimum values of θc, for each process. Minimum values of θc of models are compared with θc values for actual treatment systems.