Anaerobic Electrochemical Membrane Bioreactor (AnEMBR) for Low-Strength Wastewater Treatment with Resource Recovery

Abstract

A new hybrid system that combines a microbial electrolysis cell and membrane bioreactor using electrically conductive, porous, hollow-fiber membrane was developed to treat low organic strength solutions (300 mg COD/L) and recover energy in the form of biogas. This new system is called an anaerobic electrochemical membrane bioreactor (AnEMBR). The nickel-based hollow-fiber serves the dual function of cathode electrode for hydrogen evolution and membrane to filter the treated effluent. The system was operated for 70 days and recovered up to 71% of the substrate energy as methane rich biogas due to biological conversion of the hydrogen evolved at the cathode surface to methane by hydrogenotrophic methanogens. At an applied voltage of 0.5 V the energy density of the produced biogas exceeded the electrical energy required to operate the system by 53%. Findings also suggest that hydrogen bubble formation, cathode potential and localized alkaline pH at the cathode membrane surface may help mitigate membrane fouling.