Boosting bioelectricity performance in sediment microbial fuel cells with raw bamboo biochar as a sustainable energy source

Abstract

Sediment microbial fuel cell (SMFC) is a sustainable technology to generate bioelectricity for bioenergy production. In this study, bamboo biochar is mixed with coastal benthic sediment from oyster farm as conductive aid to optimize SMFC capacity for bioelectricity production. Laboratory-scale SMFCs are constructed with different biochar dosages, including control (SMFC-P0) and biochar cases (SMFC-P5, SMFC-P10 and SMFC-P20), to confirm the effect of biochar on bioelectricity generation and carbon sequestration. Operating SMFCs with a moderate dosage of bamboo biochar in SMFC-P5 (5g biochar) and SMFC-P10 (10g biochar) reduces internal resistance by 29.8 % and 57.5 %, resulting in high output voltage for SMFC-P5 (23 mV) and SMFC-P10 (68 mV), with a 1.3 and 3.2-fold increase, respectively. SMFC-P10 achieves maximum power density of 19.7 mW/m² with optimal biochar addition in anodic region, enhancing overall SMFC performance due to reduction in ohmic resistance. SMFC-P10 exhibits the highest redox activity, resulting in the highest current response during initial (10.4 mA) and final (8.22 mA) cyclic voltammetry. High electrode capacitance due to biochar addition minimizes charge transfer resistance, improving electron transfer. Anodic biofilm thrives under moderate biochar dosages below 2 %. Biochar addition reduces sediment CO₂ emissions, indicating that it improves soil quality and effectively sequesters soil carbon.