Verification of Anaerobic Biofilm Model for Phenol Degradation with Sulfate Reduction

Abstract

A mathematical model was developed to describe phenol degradation with sulfate reduction in an anaerobic biofilm process. The model incorporates the mechanisms of diffusive mass transport and Monod kinetics. The model was solved using a combination of the orthogonal collocation method and Gear's method. A pilot-scale column reactor was conducted to verify the model. The batch kinetic tests were independently conducted to determine nine biokinetic coefficients used in the model while shear loss and initial thickness of the biofilm were assumed so that the model simulated the substrate concentration results very well. The removal efficiencies for phenol and sulfate are 98 and 88%, respectively. At a steady-state condition, the experimental data of phenol and sulfate concentrations were higher than those obtained from the model. The reason was that the effect of shear loss became significant as the biofilm grew thicker. The higher shear loss resulted in the more-suspended biomass. The suspended biomass decomposed and released soluble microbial products which increased the substrate effluent concentrations. The procedures presented in this paper could be employed for the design of anaerobic biofilm reactor systems for the biodegradation of multiple substrates.