Treatment of phenolic wastewater by anaerobic fluidized bed microbial fuel cell using carbon brush as anode: microbial community analysis and m-cresol degradation mechanism

Anaerobic fluidized bed microbial fuel cell (AFB-MFC) is a technology that combines fluidized bed reactor and microbial fuel cell to treat organic wastewater and generate electricity. The performance and the mechanism of treating m- cresol wastewater in AFB-MFC using carbon brush as biofilm anode were studied. After 48 h of operation, the m- cresol removal efficiency of AFB-MFC, MAR-AFB (fluidized bed bioreactor with acclimated anaerobic sludge), MAR-FB (ordinary fluidized bed reactor with only macroporous adsorptive resin) and AST (traditional anaerobic sludge treatment) were 95.29 ± 0.67%, 85.78 ± 1.81%, 71.24 ± 1.86% and 70.41 ± 0.32% respectively. The maximum output voltage and the maximum power density of AFB-MFC using carbon brush as biofilm anode were 679.7 mV and 166.6 mW/m 2 respectively. The results of high-throughput sequencing analysis indicated the relative abundance of dominant electroactive bacteria, such as Trichococcus , Geobacter , and Pseudomonas , on the anode carbon brushes was higher than that of AST, and also identified such superior m- cresol-degrading bacteria as Bdellovibrio , Thermomonas , Hydrogenophaga , etc. Based on the determination of m- cresol metabolites detected by Gas Chromatography–Mass Spectrometry (GC–MS), the possible biodegradation pathway of m- cresol under anaerobic and aerobic conditions in AFB-MFC was speculated. The results showed that m- cresol was decomposed into formic acid–acetic anhydride and 3-methylpropionic acid under the action of electrochemistry, which is a simple degradation pathway without peripheral metabolism in AFB-MFC.