Coupled PFOA removal and bioelectricity generation in a pilot-scale Agrostis stolonifera constructed wetland-microbial fuel cell

Perfluorooctanoic acid (PFOA) is a persistent and recalcitrant pollutant widely detected in aquatic environments. Constructed wetland–microbial fuel cells (CW–MFCs) represent a promising strategy for simultaneous pollutant removal and energy recovery; however, the synergistic effects of plant–circuit coupling remain poorly understood. Here, a novel pilot-scale red soil CW–MFC planted with Agrostis stolonifera was constructed under closed-circuit (C-PMFC) and open-circuit (O-PMFC) modes, with an unplanted closed-circuit system (C-UPMFC), to reveal the potential and underlying mechanisms of simultaneous PFOA wastewater remediation and bioelectricity generation. C-PMFC achieved the highest PFOA removal efficiency (94.9%) and enhanced plant growth and physiological activity, with PFOA accumulation reaching 976.8 ng/g in roots and 1040.4 ng/g in leaves. A . stolonifera –closed circuit coupling improved electricity generation, producing a maximum power density of 670 mW/m 3 and a normalized energy recovery of 5.03 × 10 −3 kWh/kgCOD. Metagenomic absolute quantitative analysis revealed enrichment of electroactive bacteria Geobacter , Nitrospira, Geomonas , and Dechloromonas , and fungal Aspergillus and Trichoderma , alongside elevated abundances of key functional genes involved in chemotaxis, electron transport, stress adaptation, and membrane homeostasis. Meanwhile, metabolomic profiling showed intensified production of organic acids, aromatic intermediates, and electron mediators, which collectively promoted extracellular electron transfer and pollutant transformation. Moreover, UHPLC–HRMS analysis identified short-chain perfluorocarboxylic acids and aromatic fluorinated products, suggesting that PFOA degradation followed stepwise chain-shortening defluorination and deep decarboxylation–defluorination–cyclization. These findings highlight the potential of CW–MFCs for integrating PFAS remediation with energy recovery, supporting sustainable resource management and wastewater treatment systems.