Modeling transient substrate loads in completely mixed aeration basins at hydraulic steady state

Abstract

A numerical technique for predicting the response of a completely mixed activated sludge system (with recycle) to transient substrate inputs is presented. Substrate utilization and biomass growth are modeled by Monod kinetics. Computational efficiency is achieved by a) “locally linearizing”; the Monod expression, and b) decoupling the two mass balances by assuming biomass to be constant locally over a time step. The subsequent solutions are simple and ideally suited for PCs. Comparisons with numerical solutions of the complete equations show a high degree of accuracy and robustness for the proposed technique.