Mechanism involved in the treatment of sulfamethoxazole in wastewater using a constructed wetland microbial fuel cell system

A constructed wetland (CW) and a constructed wetland microbial fuel cell (CW-MFC) were used for 70 d to remove sulfamethoxazole from wastewater. The amount of sulfamethoxazole removed, extracellular polymer content, microbial community evolution, and changes in the abundances of genes related to antibiotic resistance were assessed. The total nitrogen, ammonia nitrogen, and sulfamethoxazole removal efficiencies were significantly (P < 0.05) higher (6.87%, 21.07%, and 11.05% higher, respectively) for the CW-MFC than the CW. Good removal efficiencies and the power generation performance indicated that the CW-MFC was more stable than the CW in the presence of sulfamethoxazole. The extracellular polymer content was lower for the CW-MFC than the CW. The phylum Proteobacteria was dominant in the CW-MFC. High Pseudomonas concentrations in the CW would have caused organic matter decomposition but not electricity generation. The Methylotenera content was 4.5 times higher in the CW-MFC anode than the CW anode. Methylotenera are able to perform denitrification and could have caused the high nitrogen removal rate for the CW-MFC. The sulfamethoxazole resistance gene copy number was much higher for the CW than the CW-MFC, indicating a higher risk of antibiotic resistance genes spreading in the CW than the CW-MFC. The results indicated that the CW-MFC is a promising technique for removing sulfamethoxazole from wastewater that offers environmental and economic benefits over alternative methods.