Nutrient Removal and Bioelectricity Generation in a Constructed Wetland-Microbial Fuel Cell: Performance of Pyrite Anode Materials

Constructed wetland-microbial fuel cell (CW-MFC) has excellent effect and potential in wastewater treatment based on many factors, such as fillers, hydraulic retention time (HRT), influent chemical oxygen demand (COD) concentration, and plants. This study explored the influence of fillers, influent COD concentrations, and HRT on the performance of CW-MFC systems to optimize the operation. Two CW-MFCs with pyrite and activated carbon as anode materials (PCW-MFC and ACW-MFC) were set up, respectively. The results showed that prolonging HRT of the systems could improve the nutrients’ removal efficiency and voltage output. The influent COD concentration had a positive import on the removal efficiency of COD, nitrate-nitrogen (NO 3 − -N), and total phosphorus (TP) in CW-MFCs. On the contrary, the removal efficiency of ammonia-nitrogen (NH 4 + -N) decreased and the voltage change showed a trend of increasing first and then decreasing with the increase of COD concentration. The optimal operating conditions of CW-MFCs were COD of 200 mg/L and HRT of 24 h. Moreover, it found that the overall performance of PCW-MFC was better than that of ACW-MFC. Microbial community analysis evaluated that the abundance of autotrophic denitrifying bacteria Thiobacillus , Dechloromonas , and Pseudomonas in the cathode layer of PCW-MFC was higher than that of ACW-MFC, indicating that pyrite could effectively promote the bacterial reproduction of nitrogen and phosphorus removal and electrogenesis.