Effects and mechanism of constructed wetland microbial fuel cell (CW-MFC) in the treatment of freshwater fish aquaculture wastewater

The freshwater aquaculture sector in China is vast and utilizes a considerable volume of water. Wastewater discharge leads to the deterioration of the water environment. Viable treatment strategies need to be implemented immediately to effectively address this contamination. The constructed wetland microbial fuel cell (CW-MFC) technology shows potential in treating wastewater from freshwater aquaculture. Therefore, the study implemented a CW-MFC system to investigate its effectiveness and process in eliminating pollutants like chemical oxygen demand (COD), inorganic nitrogen, and total phosphorus (TP) from wastewater in freshwater fish farming. Results indicated a 7.46% enhancement in COD removal by CW-MFC when contrasted with artificial wetlands (CW). The removal of NH+4-N, NO–2-N, and NO–3-N increased by 9.08, 3.99, and 6.73%. TP removal increased by 1.31%. The removal capacity of pollutants was significantly higher in CW-MFC than in CW. In addition, the electron transport system activity (ETSA) of CW-MFC was 33.33% higher than that of CW. CW-MFC significantly improves electron utilization efficiency, thereby promoting denitrification and power generation. Higher extracellular polymeric substances (EPS) content and dehydrogenase (DHA) activity in CW-MFC indicated that electron transfer facilitated microbial degradation of COD. These results demonstrate that CW-MFC has significant advantages in treating freshwater fish aquaculture wastewater compared to conventional CW.