Domestic wastewater treatment towards reuse by "self-supplied" microbial electrochemical system assisted UV/HO process.

Domestic wastewater is a potential source of water for non-potable reuse that may help address the global water, energy, and resource challenges. Herein, a "self-supplied" process through integrating microbial electrochemical system (MES) with UV/HO was developed and investigated for wastewater treatment. HO was "self-supplied" from MES while the MES catholyte was "self-supplied" from the final effluent of UV/HO. It was found that the MES accomplished > 80 % degradation of chemical oxygen demand (COD) through bioanode degradation, and produced 18 - 20 mg L HO via oxygen reduction reaction in the gas diffusion cathode. The MES effluent was further treated by the UV/HO process, which achieved the complete removal of recalcitrant diclofenac and > 6 log inactivation of Escherichia coli. The enhanced treatment performance of UV/HO was demonstrated via a comparison with the control experiments (UV or HO treatment) and benefited from ·OH generation and sulfide removal. When treating the actual wastewater, the proposed system exhibited consistent treatment performance for the organic compounds and recalcitrant contaminants, and the quality of the treated water would meet the non-potable water reuse guidelines. The results of this study encourage the further exploration of emerging contaminant removal, system coordination, and use of renewable energy by the cooperation between MES and UV/HO.