Role of macrophyte species in constructed wetland-microbial fuel cell for simultaneous wastewater treatment and bioenergy generation

The aim of this study was to determine the role of plants on pollutant removal and bioelectricity production in the treatment of municipal wastewater with constructed wetland matrix incorporating microbial fuel cells (CWMFCs) compared to traditional CWs. Multi-anode unplanted and planted CW-MFCs (Iris pseudacorus, Hyacinth pink, and Phragmites australis) were established in fed-batch mode. CW-MFC modules with established vegetation had high treatment efficiencies with COD, NO3--N, NH4+-N, and PO43--P removal of 46.9-51.6%, 94.8-97.4%, 43.2-71.5%, and 96.0-97.6%, respectively, compared to 36.6%, 89.9%, 43.0%, 97.1% in the unplanted wetland module, respectively. More efficient pollutant removal and higher power production were correlated with higher plant growth. The highest maximum power density achieved was 25.14 mW/m(2) in the multi-anode CW-MFC planted with Iris pseudacorus at highest plant height (1635 cm). The CW-MFC planted with Iris pseudacorus enhanced NH4+-N removal by 66.2% and significantly contributed to bioelectricity generation by 97.5% compared to the unplanted CW-MFC. The results highlight the significant role of growing plants in the CW-MFC matrix in strengthening the bioenergy output compared with enhancement in wastewater treatment in CWMFCs. Future studies should focus on improvement in cathode potential over a long-term operation and minimize the negative role of withered plants on the planted CW-MFCs.