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Synergic degradation of 2,4,6-trichlorophenol in microbial fuel cells with intimately coupled photocatalytic-electrogenic anode

Wang, Xiaoxuan, Hu, Jingping, Chen, Qin, Zhang, Peng, Wu, Longsheng, Li, Jianfeng, Liu, Bingchuan, Xiao, Keke, Liang, Sha, Huang, Long, Hou, Huijie, Yang, Jiakuan
Water research 2019 v.156 pp. 125-135
2,4,6-trichlorophenol, Geobacter, Pseudomonas, bioaccumulation, bioanodes, biofilm, carbon, chlorine, coatings, microbial communities, microbial fuel cells, phenol, photocatalysis, pollutants, sewage, toxicity, wastewater treatment
A microbial fuel cell system with intimately coupled photocatalytic-electrogenic anode (photocatalytic-MFC) was proposed for the synergetic degradation of 2,4,6-trichlorophenol (2,4,6-TCP) which has a structure of three chlorine groups connecting to a phenol ring and is well recognized as a recalcitrant pollutant for its high toxicity, bioaccumulation and persistence. The photocatalytic-electrogenic anode was prepared by coating mpg-C3N4 on a carbon felt anode, followed by inoculating with municipal sewage and acclimating with 2,4,6-TCP at gradient concentrations. Improved TCP degradation was achieved, showing 79.3% of TCP removal in 10 h with an original concentration of 200 mg L−1, which was higher than that obtained with the unilluminated MFC (66.0%) and the photocatalytic-only process (56.1%). The coupled photocatalytic-electrogenic process demonstrated different degradation pathways compared with the photocatalytic-only process, with one open-chain compound (2-chloro-4-keto-2-hexenedioic acid, 2-CMA) detected in the photocatalytic-MFC system. Microbial community analysis revealed that Pseudomonas, instead of Geobacter observed in the unilluminated MFC bioanode, dominated in the photocatalytic-electrogenic anode MFC biofilm, which might be responsible for enhanced current generation in the coupled system. In addition, biofilm rich with Rhodococcus on air-cathode was also responsible for the enhanced TCP removal. This research provides an efficient strategy for the treatment of wastewater with recalcitrant contaminants by intimate-coupling of the photocatalytic and the electrogenic processes.