Fe/Mn-based filler simultaneously enhance wetland purification and carbon reduction by inducing anaerobic methane oxidation coupled with autotrophic denitrification

To address low carbon sources and high GHG emissions in wetland treatment, this study constructed an integrated wetland (CW-4) with Fe/Mn-based filler and intermittent aeration. The system fostered synergistic microbial partnerships: Methanoregula and Methanothrix performed anaerobic oxidation of methane (AOM) using Fe3+/Mn4+ as electron acceptors. The resultant Fe2+/Mn2+ then fueled autotrophic denitrification by Acidovorax and Acinetobacter, while Geobacter and Massilia concurrently contributed to nitrogen removal. This Fe/Mn-mediated coupling process achieved high removal efficiencies of 96.7% for TN and 82.9% for TP, while reducing CH4 and CO2 emissions by 83.6% and 77.1%, respectively. This study elucidate the critical microbial roles in enabling simultaneous pollutant removal and carbon mitigation.