Sensitivity Analysis of Phenol Degradation with Sulfate Reduction Under Anaerobic Conditions

Abstract

This study derives a mathematical description of the kinetics of phenol degradation with sulfate reduction by an anaerobic mixed-culture biofilm on an inert medium. The model incorporates the mechanisms of diffusive mass transport and Monod kinetics. It is solved using both the orthogonal collocation method and Gear’s method. Sensitivity studies were performed to investigate the dependence of process dynamics on the model parameters pertaining to biokinetic parameters, liquid film mass transport, and the biofilm and reactor operational parameters. Sensitivity analysis quantifies the magnitude of the effect of each variable on the simulated results using the least-square method. The transient-state process dynamics are sensitive to the biokinetic parameters including yield coefficient of phenol-utilizing bacteria, Monod maximum specific utilization rate of phenol, and the decay coefficient of phenol-utilizing bacteria. The process efficiency is also sensitive to biofilm parameters such as biofilm density of phenol-utilizing bacteria and initial biofilm thickness , and to such operational parameters as the influent phenol concentration and the hydraulic retention time of the system. The process dynamics are relatively insensitive to mass transport parameters, including the film transfer coefficient of phenol and the diffusion coefficient of phenol. Sensitivity analysis of the process dynamics to model parameters helps determine how to alter process conditions to enhance removal efficiency.