Enhancement of domestic wastewater treatment in CW-MFC systems using carbon nanotubes and manganese oxide composite electrodes

The authors systematically explored the application of different electrode material combinations in microbial fuel cell-constructed wetland (CW-MFC) systems and their impact on wastewater treatment and electricity recovery performance.Synergistic effects refer to CNTs (conductivity) and MnO2 (redox catalysis) jointly enhancing electron transfer and microbial metabolism. By designing four groups of electrode material combinations—including carbon fiber, carbon fiber + MnO₂, carbon nanotubes (CNTs), and CNTs + MnO₂—the performance of each combination in terms of nitrogen removal efficiency and electricity output was evaluated. Experimental results show that the carbon nanotube and MnO₂ composite material (CNTs+MnO₂-MFC) demonstrated excellent performance in domestic wastewater treatment. After 72 h, CNTs+MnO 2 increased TN and organic nitrogen removal by 35.8 % and 45.2 %, respectively. Meanwhile, the removal rate of chemical oxygen demand (COD) stabilized at over 80 % in the later stages of the experiment. Additionally, the conductivity of the CNTs+MnO₂-MFC combination fluctuated between 2.8 and 3.5 ms/cm, exhibiting high conductivity and system stability. Electrode-driven optimization of microbial community structure enhanced electricity generation. Highlight % gains (TN: +35.8 %, COD: +40.6 %) and peak power density (1.8 mW/cm 2 ).The research findings indicate that these composite electrode materials can effectively improve the removal efficiency of nitrogen and COD in domestic wastewater within CW-MFC systems, as well as enhance electricity recovery performance.