Understanding the effects of electrical exposure mode on membrane fouling in an electric anaerobic ceramic membrane bioreactor

Anaerobic membrane bioreactor (AnMBR) with the application of electric field (EAnMBR) can alleviate fouling. However, an energy-efficient operation mode with good treatment and anti-fouling performance is still desired. This study explored the actual performance of EAnMBR under two electrical exposure modes, continuous electric field (CEF) and intermittent electric field (IEF). With the conductive ceramic membrane as cathode, the EAnMBR presented a significant improvement in fouling alleviation, total phosphorus removal efficiency, and methane yields under the appropriate electric field of 1.0V/cm. The IEF mode of 2min-on/8min-off mode could improve carbonate and nitrogenous removal efficiencies by facilitate microbial metabolism compared to CEF mode, and the discrepancy of phosphorus removal efficiency and methanogenesis between these two modes were only within 6%. Notably, its energy requirement was estimated to be one-fifth fold that of CEF. The overall antifouling mechanism was systematically unveiled under two operation modes. Long electrical stimulation time promotes electrostatic repulsion and electrocoagulation deposition for fouling control, particularly during the first stage of concentration polarization formation and particles deposition and during the second stage of particles attachment and dynamic fouling formation. These results proved that the IEF mode is feasible and effective in achieving stable EAnMBR effluent quality, mitigating fouling, and saving electrical energy for carbon peaking and neutrality goals.