Effects of biochar anodes in rice plant microbial fuel cells on the production of bioelectricity, biomass, and methane

This study investigated the potential benefits of using biochar granules as an alternative to the standard carbon felt anode in microbial fuel cells (MFC). Single-chamber cylindrical air-cathode MFCs were filled with sandy loam soil. Rice plants (Oryza sativa L.) cultivar FARO 44 were grown in plant MFCs (PMFCs). The performance of PMFC was compared with that of the soil MFC (SMFC) lacking rice plants. During 125 days of operation, the highest power density was 41.41 mW m−2 of cathode area and it was observed in PMFC with carbon felt anode (PMFC-RCF). In PMFC with biochar anode (PMFC-RBC), the power density was lower, and the highest value recorded was 11.11 mW m−2. On average (over the 125 days), PMFCs and SMFCs equipped with biochar anodes produced less bioelectricity, 16 and 27 percent, respectively, of those equipped with carbon felt anodes. On the other hand, methane emissions from PMFCS and SMFCs equipped with biochar anodes were reduced by 39% and 19%, respectively, when compared to those with carbon felt anodes. It was also observed that the total plant biomass was not significantly affected by the types of anode used. More studies are required to further improve the bioelectricity production of MFCs incorporated with biochar knowing that they have the benefit of reducing methane emission without decreasing the plant biomass yield.