Mathematical Modeling of Bioregeneration in GAC Columns

Abstract

A mathematical model of simultaneous adsorption and biodegradation in beds of sorptive media is developed and tested. The model considers a single substrate; it describes adsorption by the Fruendlich isotherm and surface diffusion in the adsorbent, while biodegradation is described by Monod kinetics and diffusion through a biofilm attached to the exterior of the adsorbent. A film transport resistance and growth and decay of the biofilm over time also are included. Model performance is compared with experimental data for both bioregeneration rate and substrate concentration in the liquid phase. The model is able to predict bioregeneration rate adequately when the biomass loss coefficient was increased above its calculated value. However, the model could not match the bioregeneration rate and liquid phase concentration measurements simultaneously. Concentration predictions are somewhat higher than measured values. The research demonstrates the feasibility of modeling the complex interactions involved in treatment processes simultaneously supporting adsorption and biodegradation, although additional refinement and testing of the model are required.