Advanced oxidation enhanced microbial electrolysis cell coupled with anaerobic digestion: A novel approach to coal gasification wastewater treatment

Coal gasification wastewater (CGW) contains a range of refractory and toxic organic pollutants with low biodegradability and significant biological toxicity. This study synthesized a hemin-graphene (H-graphene) catalyst for permonosulfate (PMS) activation. The MEC-AD (Microbial electrolysis cell- Anaerobic digestion) reactor (K1) was designated as the control group. The experimental groups were the MEC-AD reactor (K2) with PMS and H-graphene, and the MEC-AD reactor (K3) with advanced oxidation as a synthetic CGW pretreatment. The results demonstrated that the COD removal rates of K1, K2 and K3 reactors were 76.7 %, 79.5 % and 87.4 %, while the total phenol removal rates were 74.1 %, 90.1 % and 100 %, respectively. Quinoline and indole were removed at rates greater than 90 % in the microbial electrolytic cell reactors K2 and K3, and 100 % in the K3 reactor. In K2 and K3, there was a considerable decrease in the abundance of unclassified _ f _ Alcaligenaceae, Arenimonas and unclassified _ f _ Gracilibacteraceae as compared to K1. The abundance of unclassified _ p _ Zixibacteria, Candidatus _ Caldatribacterium, unclassified _ c _ JS1 and JGI-0000079-D21, which are responsible for promoting the anaerobic degradation of long-chain fatty acids and anaerobic fermentation of acid production increased.