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The constructed wetland coupled with microbial fuel cell (CW-MFC) systems operated at different substrate concentration and pH influents were evaluated for bioelectricity generation, contaminant removal and microbial community structure. Performance of CW-MFC was evaluated at organic loading rate of 75.3gCODm-3d-1 and pH gradients of (5.18±0.14, 7.31±0.13, and 8.75±0.12) using carbon fiber felt as electrodes. Peak power density was observed at slightly neutral influent condition. Compared with the open circuit CW-MFC, average COD and NO3-N removal efficiency in CW-MFC increased by 8.3% and 40.2% respectively under slightly neutral pH of influents. However, the removal efficiency and bioenergy production have been inhibited with acidic influents. The relative abundance of beta-Proteobacteria, nitrobacteria and denitrifying bacteria was significantly promoted in closed-circuit CW-MFC. Using of CW-MFC as a biochemical method for nitrate removal and bioelectricity generation under slightly neutral and alkaline influent conditions was a promising technology.

Integrating microbial fuel cell with constructed wetland (CW-MFC) is a novel way to harvest bioelectricity during wastewater treatment. In this study, the bioelectricity generation, containment removal and microbial community distribution in CW-MFC as affected by substrate material sizes and aquatic macrophyte were investigated. The planted CW-MFC with larger filler size showed a significant promotion of the relative abundance of electrochemically active bacteria (beta-Proteobacteria), which might result in the increase of bioelectricity generation in CW-MFC (8.91mWm-2). Additionally, a sharp decrease of voltage was observed in unplanted CW-MFC with smaller filler size in Cycle eight. However, the peak COD (86.7%) and NO3-N (87.1%) removal efficiencies were observed in planted CW-MFC with smaller filler size, which was strongly related to the biodiversity of microorganisms. Generally, the acclimation of exoelectrogens as dominant microbes in the anode chamber of planted CW-MFC with larger filler size could promote the bioelectricity generation during wastewater treatment.