A new anaerobic treatment system that combined a microbial electrolysis cell (MEC) with membrane filtration using electrically conductive, porous, nickel-based hollow-fiber membranes (Ni-HFMs) was developed to treat low organic strength solution and recover energy in the form of biogas. This new system is called an anaerobic electrochemical membrane bioreactor (AnEMBR). The Ni-HFM served the dual function as the cathode for hydrogen evolution reaction (HER) and the membrane for filtration of the effluent. The AnEMBR system was operated for 70 days with synthetic acetate solution having a chemical oxygen demand (COD) of 320 mg/L. Removal of COD was >95% at all applied voltages tested. Up to 71% of the substrate energy was recovered at an applied voltage of 0.7 V as methane rich biogas (83% CH4; <1% H2) due to biological conversion of the hydrogen evolved at the cathode to methane. A combination of factors (hydrogen bubble formation, low cathode potential and localized high pH at the cathode surface) contributed to reduced membrane fouling in the AnEMBR compared to the control reactor (open circuit voltage). The net energy required to operate the AnEMBR system at an applied voltage of 0.7 V was significantly less (0.27 kWh/m3) than that typically needed for wastewater treatment using aerobic membrane bioreactors (1-2 kWh/m3).

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suspension. These results show that the new rectangular reactor design, which had increased rates of hydrogen production, successfully delayed the onset of cathode biofouling and improved reactor performance.

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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.