Up-flow constructed wetland-microbial fuel cell: Influence of floating plant, aeration and circuit connection on wastewater treatment performance and bioelectricity generation

Abstract

The influence of floating plant (Eichhornia crassipes), supplementary aeration and circuit connection on wastewater treatment performance and electricity production using up-flow constructed wetland-microbial fuel cell (UFCW-MFC) were investigated in this study. This study was operated for four stages, where stage I was conducted without plant and aeration; stage II was planted with Eichhornia crassipes; supplementary aeration was provided in stage III; stage IV was operated in open circuit. The supplementary aeration showed the most significant effect on the performance of UFCW-MFC compared to floating plant and circuit connection. The optimum performance of wastewater treatment and electricity production was found in stage III as the oxygen was supplied by the floating plant and supplementary aeration for the degradation of organic matters as well as the generation of bioelectricity. The chemical oxygen demand (COD), NH4+ and NO3− removal efficiencies were 99 %, 96 % and 44 %, respectively. E. crassipes and supplementary aeration improved the dissolved oxygen (DO) concentration at the cathodic region and enhanced the NH4+ removal by 10 % (Stage II) and 67 % (Stage III) compared to the non-planted bioreactor (stage I). Closed circuit also performed 6 % better than open circuit at sampling point 1 (S1) in COD reduction. The maximum power density, voltage output, coulombic efficiency and normalized energy recovery were 45.46 ± 3.83 mW/m3, 291 ± 62 mV, 2.15 %, 15.09 Wh/kg COD and 0.31 W/m3, respectively.