In recent years, microbial electrochemical systems (MESs) have demonstrated to be an environmentally friendly technology for wastewater treatment and simultaneous production of value-added products or energy. However, practical applications of MESs for the treatment of recalcitrant wastewater are limited by their low power output and slow rates of pollutant biodegradation. As a novel technology, hybrid MESs integrating biodegradation and photocatalysis have shown great potential to accelerate the degradation of bio-recalcitrant pollutants and increase the system output. In this review, we summarize recent advances of photo-assisted MESs for enhanced removal of recalcitrant pollutants, and present further discussion about the synergistic effect of biodegradation and photocatalysis. In addition, we analyse in detail different set-up configurations, discuss mechanisms of photo-enhanced extracellular electron transfer, and briefly present ongoing research cases. Finally, we highlight the current limitations and corresponding research gaps, and propose insights for future research.
Glyphosate, one of the most used herbicides worldwide, is known as an aquatic contaminant of concern, and has been identified as presenting adverse impacts in agroecosystems, due to a somewhat limited natural chemical and biological degradation in the environment. In this study, we investigated the degradation of glyphosate in microbial electrochemical systems (MESs), and compared the performance and the microbial composition of enriched anodic biofilms with those shown by native microbial communities. The reduction of glyphosate content observed in MESs (approx. 70 %) was much higher than in non-electroactive microbial cultures (approx. 49 %). The analysis of the microbial communities by 16S amplicon sequencing revealed a significant difference between the microbial community composition of MESs anodic biofilms and non-electroactive enriched communities. The anodic biofilms were dominated by Rhodococcus (51.26 %), Pseudomonas (10.77 %), and Geobacter (8.67 %) while in non-MESs cultures, methanogens including Methanobrevibacter (51.18 %), and Methanobacterium (10.32 %), were the dominant genera. The present study suggested that MESs could be considered as a promising system for complete degradation of glyphosate from waters polluted by this herbicide.