Research Progress in Photocatalytic-Coupled Microbial Electrochemical Technology in Wastewater Treatment

Photocatalytic-coupled microbial electrochemical systems (MESs) represent an emerging wastewater treatment technology which aims to address the limitations of traditional methods, such as the inadequate removal of refractory pollutants and excessive energy consumption. This technology realizes the simultaneous degradation of refractory pollutants in wastewater and bioenergy recovery, demonstrating significant potential for development. However, the practical application of this technology is currently hindered by challenges including insufficient electrical power output, poor stability of photoelectric electrodes, and the design of amplified application systems. This review comprehensively examines the common coupling methods and principles of photocatalytic-coupled microbial electrochemical systems. Compared to previous studies, it provides a detailed analysis of the optimal configurations for treating wastewater containing various components, such as recalcitrant organic compounds, heavy metals, and nitrates, to achieve maximum efficiency. Moreover, it summarizes the synergistic effects observed between photocatalysis and MES that enhance the degradation efficiency of pollutants through various pathways, including increasing the potential difference of cytochromes, promoting the formation of conductive nanowires, accelerating the electron transfer rates, and inhibiting electron–hole recombination. Finally, this review highlights the challenges in practical applications and proposes future research directions to facilitate the further development of this technology.