Bioelectricity production using shade macrophytes in constructed wetlands-microbial fuel cells

Abstract

The coupling of constructed wetlands (CW) to microbial fuel cells (MFC) has become a promising hybrid technology due to its high compatibility to generate electricity and remove pollutants from wastewater. In the present study, the bioelectricity production generated from constructed wetlands-microbial fuel cells (CW-MFCs) was evaluated using four species of shade macrophytes: <i>Aglaonema commutatum</i>, <i>Epipremnum aureum</i>, <i>Dranacaena braunni,</i> and <i>Philodendron cordatum</i>. The CW-MFCs were operated in a continuous upflow mode with a hydraulic retention time (HRT) of 4 d. The systems were fed with synthetic water without an external carbon source. The bioelectrochemical systems were operated under diffuse radiation conditions (shadow). <i>Philodendron cordatum</i> was the macrophyte species that produced a maximum voltage of 103 mV, with a power density of 12.5 mW/m². High voltages were obtained when the diffuse radiation in the CW-MFCs was 3000-4000 µmol^.m²/s. The maximum production of root exudates was 20.6 mg/L as total organic carbon for the <i>Philodendron cordatum</i> species. <i>Philodendron cordatum</i> was the macrophyte species that obtained high conversion efficiency (0.0014%), compared to other macrophyte species (< 0.0008%). In the CW-MFCs systems it was observed that the bioelectricity production was mainly due to the quantity of the root exudates released into the rhizospheres of the plants.