In-situ integration of microbial fuel cell with hollow-fiber membrane bioreactor for wastewater treatment and membrane fouling mitigation

Abstract

A hollow-fiber membrane bioreactor was integrated with a microbial fuel cell to develop a novel system of MFC–MBR based on the utilization of electricity recovered by the MFC for wastewater treatment improvement and membrane fouling mitigation in the MBR. In this system, a maximum power density of 2.18W/m3 and an average voltage output of 0.15V were achieved at an external resistance of 50Ω. The removal efficiencies of COD, ammonia nitrogen (NH4+-N) and total nitrogen (TN) in the MFC–MBR were improved by 4.4%, 1.2% and 10.3%, respectively. It is worth noting that, in addition to reducing the deposition of sludge on the membrane surface by the electric field force, the MFC–MBR also alleviated the membrane fouling by sludge modification. Compared with the control MBR (C-MBR), less loosely bound extracellular polymeric substances (LB-EPS), lower SMPp/SMPc ratio, more homogenized sludge flocs and less filamentous bacteria were obtained in the MFC–MBR, which improved the dewaterability and filterability of the sludge. The cake layer on the membrane formed by the modified sludge was more porous with lower compressibility, significantly enhancing the membrane filterability. A proof of concept of an MFC–MBR was provided and shown to be effective in membrane fouling mitigation with efficient wastewater treatment and energy recovery, demonstrating the feasibility of the minute electricity generated by the MFC for membrane fouling alleviation in the MBR.