Advances in wastewater treatment by combined microbial fuel cell-membrane bioreactor

A combined approach of treating domestic wastewater using microbial fuel cell (MFC) and membrane bioreactor (MBR) has been developed as a promising and reliable technology of wastewater treatment. Treatment of wastewater in a single stage MFC has limitation to achieve the required treatment efficiency and utilize the effluent for irrigation or any other possible reuse without further treatment. Therefore, a two-stage continuous process was developed for treating medium strength industrial wastewater combining MFC and submerged MBR, resulting recovery of high quality effluent through ultrafiltration membrane. Synthetic wastewater with sucrose as carbon source, having total chemical oxygen demand (COD) of 3 g/L, was introduced in anodic chamber of MFC in continuous mode at a constant organic loading rate of 1.5 kg COD/m.day during the experimental period. MFC was operated with hydraulic retention time (HRT) of 2 days and effluent was continuously collected in aerobic MBR, operated with 10 h of HRT. Submerged hollowfibre membrane assembly was attached to draw permeate from MBR. In the first stage, MFC generated effluent with reduced total and soluble COD of 0.76 ± 0.07 g/L and 0.370 ± 0.012 g/L. The electrical behaviour of MFC was studied by polarization curve resulting in maximum volumetric power density of 1.021 W/m. The MFC effluent was further treated in MBR which demonstrated 93.70 ± 0.28 % and 76.86 ± 2.78 % of soluble COD and nitrogen removal efficiency, respectively. MBR effluent, after passing through ultrafiltration membrane, produced permeate with total COD and TSS concentration as 0.05 ± 0.01 g/L and less than 0.005 g/L, respectively. Hence, the study revealed a two-stage reliable process of organic wastewater treatment using MFC–MBR technology, overall achieving more than 98% removal of total COD and almost complete removal of suspended solids. The combined process effectively generated high – quality recyclable effluent and bio-electricity for onsite application.