Removal of AOC in biological water treatment processes: A kinetic modeling approach

Abstract

In this paper, a steady-state biofilm model is applied for modeling substrate removal by plug-flow bioreactors in biological water treatment. The model is used with assimilable organic carbon (AOC) data from a previous pilot scale study to estimate the essential physical and kinetic parameters required for designing biological water treatment processes. The successful fitting of the model to the data demonstrates the applicability of this modeling approach for water treatment and that AOC can be used as at least a surrogate for the overall biodegradable organic matter. The model is used to obtain process insights. It is shown that there is an approximately linear relationship between substrate removal and influent concentration. For a plug-flow packed bed bioreactor, a quantity designated as the dimensionless empty bed contact time, X∗, is defined. The slope of the linear relationship, representing the approximate percentage removal of the substrate, is shown to be mainly determined by X∗. Percentage removal increases convexly with increasing X∗, however beyond a certain value of X∗, further increases achieve little improvement. Other dimensionless parameters affect the convexity of the curve.