Performance of carbon fiber cathode membrane with C-Mn-Fe-O catalyst in MBR-MFC for wastewater treatment

An effective new cathode membrane (CM) with carbon fiber cloth, polyvinylidene fluoride (PVDF) and a catalyst containing C, Mn, Fe and O elements, was prepared. Firstly, the catalyst was in-situ formed on the fiber cloth via impregnation and high-temperature pyrolysis. Then for cathode membrane preparation, the fiber cloth after pyrolysis was coated with PVDF via casting and phase inversion. The membrane prepared performed well as electrodes and successfully integrated MBR with MFC. The surface morphology of the CM was studied using scanning electronic microscopy (SEM), and energy dispersive X-ray spectroscopy (EDX) analysis confirmed the existence of PVDF and catalyst components. The carbon cathode membrane with C-Mn-Fe-O catalyst (CCMT) was compared with carbon fiber cloth cathode membrane without the catalyst (CCMO) in MFC/MBR, the coupled wastewater treatment system (without inoculating sludge biomass in cathode chamber). In the configured system, the 2 cm distance between the electrodes could effectively isolate the anodic environment (DO=0.01 mg L−1) from the aerobic cathodic condition (DO=4.81 mg L−1). In the system with CCMT, the removal rates of COD, NH4+-N, and TP were above 90%, 80% and 65%, respectively, and removal of NH4+-N was found converted to N2. Its maximum generated power density reached 1358 mW m−3, 4 times higher than using CCMO (337 mW m−3). The inner resistance in system with CCMT was 71 Ω, 2.7 times lower than using CCMO (194 Ω).