Kinetics of Chromium(VI) Reduction with Acetate Biodegradation byEscherichia coli33456 in a Fixed Biofilm Reactor

Abstract

Abstract A kinetic model was developed to describe the Cr(VI) reduction with acetate biodegradation by Escherichia coli 33456 in a fixed film reactor. A laboratory-scale column reactor was used to verify the model system. Batch kinetic tests were independently performed to determine biokinetic parameters used in model simulation. With assumed values of initial biofilm thickness (Lf0), the mathematical model simulated well experimental results for effluent concentrations of Cr(VI) and acetate, suspended E. coli cells, and Cr(III) production. The concentration of suspended E. coli cells reached 11.4 mg cell/L while the thickness of attached E. coli cells was estimated to be 27.8 μm at a steady state condition. At steady state, removal efficiencies of Cr(VI) and acetate were about 92% and 90%, respectively, under influent Cr(VI) loading rate (11.3 g/[m3·day]) and acetate loading rate (664.4 g/[m3·day]) at a hydraulic retention time of 10.7 h, while the effluent concentration of Cr(III) was ∼1.65 mg/L. The ki...