Nutrients Removal and Bioelectricity Generation in a Constructed Wetland-Microbial Fuel Cell: Effect of Several Operational Factors

CW-MFC has excellent effect and potential in wastewater treatment based on many factors, such as fillers, hydraulic retention time (HRT), influent COD concentration, plants etc. This study explored the influence of influent COD concentrations and HRT on the performance of CW-MFC in order to optimize the operation. The results showed that prolonging HRT of the system could improve the nutrients removal efficiency and voltage output. And the influent COD concentration had an positive import on the removal efficiency of COD, NO3--N and TP in CW-MFC. On the contrary, with the increase of COD concentration, the removal efficiency of NH4+-N decreased and the voltage change showed a trend of increasing first and then decreasing. The optimal operating conditions of CW-MFC were COD of 200 mg/L and HRT of 24 h. Moreover, Pyrite and activated carbon were also used as anode materials to reveal the effects of fillers on the performance of CW-MFC system. It found that the overall performance of Pyrite-CW-MFC (PCW-MFC) was better than that of Activated carbon-CW-MFC (ACW-MFC). Microbial community analysis evaluated that the abundance of autotrophic denitrifying bacteria Thiobacillus, Dechloromonas and Pseudomonas in the cathode layer of PCW-MFC was higher than that of ACW-MFC, indicating that pyrite could effectively promote the bacteria reproduction of nitrogen and phosphorus removal and electrogenesis.