Minimal bamboo biochar dosing as sediment additive in sediment microbial fuel cells for bioelectricity production and...

Sediment resistivity limits the performance of sediment microbial fuel cells (SMFCs) by hindering mass electron transfer in the anodic region. This microcosm study evaluates the effect of bamboo biochar as a conductive additive at different dosages: SMFC-0 (0%), SMFC-0.1 (0.02%), SMFC-1 (0.2%), and SMFC-10 (2%). The study examines the current density, polarization behavior, redox activity, elemental composition, textural properties, anodic biofilm morphology and nutrient removal. The results show that 2% biochar (SMFC-10) increase sediment conductivity by 1.2-fold and reduces ohmic loss for mass electron transfer, achieving the highest power density (26.01 mW/m²) and current output (171 mA/m²). Field emission scanning electron microscopy (FESEM) analysis reveals dense anodic biofilm formation in SMFC-10, supporting higher bioelectricity generation. SMFC-10 improves pollutant removal and mitigates pollutant release into the overlying water, reducing ammonia‑nitrogen (NH₃-N) from 5 to 1 mg/L and chemical oxygen demand (COD) from 163 to 33 mg/L. High specific BET surface area (430.15 m²/g), small pore size (1.62 nm) and high carbon content (79.46%) of biochar contribute to improve performance and long-term stability (165 days) without nutrient replenishment. These findings demonstrate that bamboo biochar is a promising sediment additive to enhance SMFC power generation and water quality.