A two-stage microbial fuel cell and anaerobic fluidized bed membrane bioreactor (MFC-AFMBR) system for effective domestic wastewater treatment

Microbial fuel cells (MFCs) are a promising technology for energy-efficient domestic wastewater treatment, but the effluent quality has typically not been sufficient for discharge without further treatment. A two-stage laboratory-scale combined treatment process, consisting of microbial fuel cells and an anaerobic fluidized bed membrane bioreactor (MFC-AFMBR), was examined here to produce high quality effluent with minimal energy demands the combined system was operated continuously for 50 days at room temperature (25 °C) with domestic wastewater having a total chemical oxygen demand (tCOD) of 210 ± 11 mg/L. At a combined hydraulic retention time (HRT) for both processes of 9 h, the effluent tCOD was reduced to 16 ± 3 mg/L (92.5% removal), and there was nearly complete removal of total suspended solids (TSS; from 45 ± 10 mg/L to <1 mg/L) the AFMBR was operated at a constant high permeate flux of 16 L/m²/h over 50 days, without the need or use of any membrane cleaning or backwashing. Total electrical energy required for the operation of the MFC-AFMBR system was 0.0186 kWh/m³, which was slightly less than the electrical energy produced by the MFCs (0.0197 kWh/m³) the energy in the methane produced in the AFMBR was comparatively negligible (0.005 kWh/m ³) these results show that a combined MFC-AFMBR system could be used to effectively treat domestic primary effluent at ambient temperatures, producing high effluent quality with low energy requirements.