Influence of applied voltage and COD on the bioelectrochemical degradation of organic matter

Abstract

Organic matter degradation was examined in an air cathode bioelectrochemical system (BES) operated in a fed-batch mode operation. The organic matter degradation rate in the air cathode BES was significantly affected by the initial concentration of organic matter with a chemical oxygen demand (COD) ranging from 25 to 600 mg/L, and by the applied voltage of 100 and 300 mV. When the initial COD concentration was less than 100 mg/L, the substrate affinity to bacteria at an applied voltage of 300 mV was slightly higher than that at 100 mV, but the substrate degradation potential that was evaluated by the ratio of maximum substrate degradation rate to saturation constant did not vary at 100 and 300 mV applied voltages. For initial COD concentrations higher than 300 mg/L, the substrate degradation potential at an applied voltage of 100 mV was higher than that at 300 mV. The anode and cathode potentials in the BES were affected by both the applied voltage and initial COD concentration, but the effect of applied voltage on the potential was increasingly important with decrease in COD concentration. The coulomb efficiency at an applied voltage of 100 mV was higher than that at 300 mV, but decreased with increase in initial COD concentration in the BES. The air cathode BES with applied voltage is an advanced wastewater treatment system for organic pollutants.