Domestic wastewater treatment towards reuse by “self-supplied” microbial electrochemical system assisted UV/H₂O₂ 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/H₂O₂ was developed and investigated for wastewater treatment. H₂O₂ was “self-supplied” from MES while the MES catholyte was “self-supplied” from the final effluent of UV/H₂O₂. It was found that the MES accomplished > 80 % degradation of chemical oxygen demand (COD) through bioanode degradation, and produced 18 - 20 mg L⁻¹ H₂O₂ via oxygen reduction reaction in the gas diffusion cathode. The MES effluent was further treated by the UV/H₂O₂ process, which achieved the complete removal of recalcitrant diclofenac and > 6 log inactivation of Escherichia coli. The enhanced treatment performance of UV/H₂O₂ was demonstrated via a comparison with the control experiments (UV or H₂O₂ 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/H₂O₂.