Treatment of formaldehyde-containing wastewater and power generation by constructed wetland–microbial fuel cells enhanced by formaldehyde-degrading bacteria

In this study, three formaldehyde-degrading bacteria, Paenibacillus, Hyphomicrobium, and Ensifer were isolated from activated sludge. Three strains of formaldehyde-degrading bacteria were enriched and added to a constructed wetland–microbial fuel cells (CW-MFC) for bioaugmentation. Three laboratory-scale devices were built: constructed wetland (CW), enhanced CW-MFC (EG), and non-enhanced CW-MFC (CG). During the 70 days of operation, a comprehensive study was conducted to investigate the impact of bioaugmentation on the performance of CW-MFC in treating formaldehyde wastewater, considering water quality, power generation, and microbial communities. The formaldehyde removal rate by the EG (98.8 % ± 0.6 %) was significantly higher than that of the CG (91.0 % ± 0.6 %) (P < 0.05). The average voltage of the EG (167.3 ± 4.8 mV) was higher than the CG (122.5 ± 2.9 mV). Bioaugmentation of a constructed wetland–microbial fuel cell can significantly improve its ability to treat formaldehyde-containing wastewater and generate electricity.