Simultaneous removal of antibiotics and nitrogen by microbial fuel cell-constructed wetlands: Microbial response and carbon–nitrogen metabolism pathways

Microbial fuel cell-constructed wetlands (MFC-CWs) are attracted extensive attention due to their simultaneous removal performance during the co-occurrence of various pollutants in wastewater. This study explored the performance and mechanisms on the simultaneous removal of antibiotics and nitrogen from MFC-CWs which packed with coke (MFC-CW (C)) and quartz sand (MFC-CW (Q)) substrate. Results showed that removal of sulfamethoxazole (93.60 %), COD (77.94 %), NH4+-N (79.89 %), NO3-- N (82.67 %), and TN (70.29 %) significantly enhanced by MFC-CW (C) due to the enhancement of relative abundance of membrane transport, amino acid metabolism and carbohydrate metabolism pathways. The results indicated that coke substrate can generate more electric energy in MFC-CW. Firmicutes (18.56-30.82 %), Proteobacteria (23.33-45.76 %), and Bacteroidetes (17.1-27.85 %) were dominant phyla in the MFC-CWs. MFC-CW (C) posed significant effects on the microbial diversity and structure, which motivated the functional microbes involved in the transformation of antibiotics and nitrogen and bioelectricity generation. Given the overall performance of MFC-CW, packing with cost-effective substrate to electrode region of MFC-CWs was found to be an effective strategy for simultaneously removing antibiotics and nitrogen in the wastewater treatment.