Modulating electrode area in microbial fuel cell enhanced floating beds: synergistic effects on bioelectricity...

Perfluorooctanoic acid (PFOA) contamination poses significant challenges for the remediation of surface water. This study evaluated how electrode surface area affects the performance of microbial fuel cell enhanced floating beds (MFC-EFBs) under PFOA stress. The results indicate that PFOA exposure significantly reduced MFC-EFBs bioelectricity generation, likely due to toxic effects on plants and microbial communities. Increasing electrode surface area from 0.04 m² to 0.08 m² partially mitigated these adverse effects, improving power density, plant photosynthetic activity, and the removal of conventional pollutants. PFOA removal in MFC-EFBs was primarily attributable to substrate adsorption (13.2-14.6%), whereas plant uptake contributed less than 5%. Although increasing electrode surface area did not significantly change overall PFOA removal efficiency (p > 0.05), it altered PFOA transport pathways within the system. Larger electrode areas enhanced the adsorption of PFOA onto the electrode surface and its subsequent phytosequestration, effectively extracting PFOA from the aqueous phase and thereby lowering its bioavailability and associated ecological risk. These results indicate that optimizing electrode surface area can enhance MFC-EFBs resilience to PFOA stress and improve treatment performance, offering a practical strategy to advance bioelectrochemical remediation of emerging contaminants in surface water.