Electron Transfer Regulation and Nitrogen Removal Pathways in Constructed Wetland with Manganese Ore and Activated Carbon Coupling Microbial Fuel Cell

• • Ammonium removal efficiency in the MO-AC-MFC system reached up to 5.5 times that of the control, demonstrating a significant enhancement in nitrogen removal performance. • • The integration of MO and AC with MFC configuration upregulated nitrogen transformation enzyme activities in biofilms, stimulating nitrification and anammox processes at the anode. • • EPS analysis confirmed that Mn2+ from manganese reduction was captured by EPS, facilitating manganese cycling and contributing to sustained electron transfer. • • Increased abundance of ETC and EET genes, along with elevated Cyt-C concentration and activity, confirmed enhanced extracellular electron transfer, which is critical for nitrogen transformation.