Bacillus sp. outperforms E. coli in microbial fuel cells for sustainable POME treatment and bioelectricity generation

Abstract The integration of biotechnology and waste-to-energy systems is critical for advancing circular economy solutions. This study evaluates the potential of Gram-positive Bacillus sp. versus Gram-negative Escherichia coli in microbial fuel cells (MFCs) for simultaneous palm oil mill effluent (POME) treatment and bioelectricity generation. Over 30 days, Bacillus sp. demonstrated superior bioremediation efficiency, degrading 52.76 % of COD from POME—significantly outperforming E. coli (35.18 %). The strain’s metabolic robustness was further evidenced by sustained bioenergy recovery (490 mV, 25 mW/m²) and efficient multi-pathway electron transfer mechanisms, evidenced by unique dual cathodic peaks in cyclic voltammetry. Electrochemical impedance spectroscopy confirmed Bacillus sp.’s lower internal resistance (104.71 Ω), suggesting enhanced extracellular electron transfer capabilities compared to E. coli (118.37 Ω). These findings emphasize the distinctiveness of microbial physiology influences biotechnological applications. The study provides a foundation for developing tailored bioelectrochemical systems using robust environmental isolates for sustainable industrial wastewater valorization, aligning with global goals for energy-positive bioremediation.