Abstract
Constructed wetlands have been widely used for organic wastewater treatment owing to low operating costs and simple maintenance. However, there are some disadvantages such as unstable efficiency in winter. In this study, a microalgal electroactive biofilm-constructed wetland was coupled with anaerobic digestion for full-scale treatment of swine wastewater. In a 12-month outdoor trial, the overall removal efficiencies of chemical oxygen demand, ammonium, nitrate, total nitrogen, total phosphorus, and nitrite reached 98.26%/95.14%, 97.96%/92.07%, 85.45%/66.04%, 95.07%/91.48%, 91.44%/91.52%, and 85.45%/84.67% in summer/winter, respectively. Hydrolytic bacteria were dominant in the anaerobic digestion part, and Cyanobium, Shewanella, and Azoarcus were enriched in the microalgal electroactive biofilm. The operating cost of the entire system was approximately 0.118 $/m3 of wastewater. These results confirm that the microalgal electroactive biofilm significantly enhances the efficiency and stability of constructed wetlands. In conclusion, the anaerobic digestion-microalgal electroactive biofilm-constructed wetland is technically and economically feasible for the treatment of swine wastewater.
[Display omitted]
•Constructed wetlands are widely used for aquaculture wastewater treatment.•Microalgal electroactive biofilm-constructed wetland coupled with anaerobic digestion was tested.•COD, NH4+-N, NO3−-N, TN, TP, & NO2−-N treatment were enhanced, even in winter.•Cyanobium, Shewanella &Azoarcus dominated microalgal electroactive biofilm.•The operating cost of the entire system was approximately 0.118 $/m3 of wastewater.