Synergistic integration of floating wetlands and microbial fuel cells via plant-microbe-electrode interactions

This study evaluated the restorative potential of integrating Microbial Fuel Cells (MFC) with Floating Treatment Wetlands (FTW) to create robust, solar-driven bio-electrochemical ecosystems. To assess the synergistic establishment of macrophytes, electrodes, and microbes, meso-scale (150 L) reactors planted with Phragmites australis and Iris pseudacorus were operated over a six-week period of increasing pollutant loads. The system demonstrated adaptive resilience; while initial phases showed ecosystem acclimatization, the mature FTW-MFC systems significantly outperformed conventional FTWs, achieving removal efficiencies of up to 94% for COD and 97% for NH₄-N. The presence of electrodes promoted bioelectrochemical processes that supported ecosystem functioning: plants in FTW-MFC reactors exhibited significantly reduced stress markers (higher chlorophyll content and photosynthetic efficiency Fv/fm) compared to conventional FTWs, suggesting enhanced physiological resilience essential for restoration projects. Bioenergy output peaked at 498 mV during the mature phase, exhibiting pronounced day-night fluctuations correlated with sunlight, indicating the system functioned analogously to a solar-driven photobioreactor. Microbiome sequencing (16S rRNA) revealed that electrodes engineered specific ecological niches, shifting rhizosphere communities toward electroactive and phototrophic genera ( Cereibacte r, Hydrogenophaga ) distinct from non-electrode controls. These findings demonstrate that bio-electrochemical integration transforms passive wetlands into active, solar-powered remediation systems. By mutually benefiting plant health and microbial activity over extended operation, this hybrid technology offers a novel approach for sustainable ecosystem restoration.