Packing blockage and power generation of constructed wetland coupled microbial fuel cell systems using biochar as electrode and filler with different ratios

Abstract

This article investigated the electrochemical performance, water purification capacity and packing clogging of constructed wetland-microbial fuel cells coupled reactors (CW-MFCs). The CW-MFCs-B (B = 100 % biochar filler) reactor performed the best under intermittent conditions, with a power density of up to 33.7 mW/m2. Regarding TOC removal, CW-MFCs-G (G = no biochar filler) was the least effective when the system was in continuous flow. The effect of the other two reactors with biochar filler addition (BG = 50 % and B = 100 %) was similar, indicating that the biochar functioned well as the CW filler to remove organic matter. Regarding NH4+-N removal, removal rates varied at different HRTs: HRT = 2 days > intermittent flow > HRT = 0.5 days. Among them, CW-MFCs-B was the most effective, with a maximum of 65.10 %. The clogging index Φb of the three reactors were 2.83 (B), 1.77 (BG), and 0.72 (G). The CW-MFCs-B reactor showed good effluent treatment and had the best electricity production but the most severe clogging. There may be a certain connection between H2O2 concentration and the degree of CW clogging. CW-MFC with biochar electrode and gravel filler may be suitable for long-term operation.