Baffled flow constructed wetland-microbial fuel cell coupling systems for combined secondary and tertiary wastewater treatment with simultaneous bioelectricity generation.

[Display omitted] • Embedding baffles in CW-MFC increased water flowing path and contact opportunity. • Combined secondary and tertiary water treatment was achieved in baffled flow CW-MFC. • Baffled flow CW-MFC had higher ammonium and total nitrogen removal efficiency. • Embedding 1 or 2 baffles in the cathode chamber led to higher maximum power density. • CW-MFC with baffles embedded in the cathode unit had different microbial community. Baffled flow constructed wetland-microbial fuel cell (BFCW-MFC) coupling systems were constructed with baffles embedded in cathode chamber. The performance of BFCW-MFCs operated at different hydraulic retention times (HRTs) was evaluated. At the representative HRT of 48 h, embedding 1 or 2 baffles (i.e., BFCW-MFC1 and BFCW-MFC2) produced 32.9 % (29.5 mW/m3) and 53.2 % (34.0 mW/m3) more power density than control system (22.2 mW/m3), respectively. Comparable organics biodegradation efficiencies were observed in BFCW-MFCs at the same HRTs. BFCW-MFC1 and BFCW-MFC2 had higher ammonium and total nitrogen removal efficiency. All systems had decreased nitrogen removal performance as shortening HRT from 72 to 12 h. Multiple nitrogen removal processes were involved, including ammonium oxidation, anammox, and heterotrophic and autotrophic denitrification. The predominant bacteria on electrodes were identified for analyzing bioelectricity generation and wastewater treatment processes. Generally, simultaneous wastewater treatment and bioelectricity generation were obtained in BFCW-MFCs, and embedding 1 or 2 baffles was preferable. [ABSTRACT FROM AUTHOR]