Effects of Carbon Source on Denitrification and Electricity Generation in Composite Packing MFC-CW for Tail Water Treatment

Abstract

The tail wastewater from sewage treatment facilities usually lacks carbon sources, and its subsequent treatment for deep nitrogen removal is difficult in natural conditions. In this study, the constructed wetland (CW) was integrated with microbial fuel cell (MFC) with high-density polyethylene (HDPE) fillers as the main matrix to improve nitrogen removal under inefficient carbon source conditions. Compared with the regular MFC and CW systems, MFC-CW attained higher nitrogen removal under low-carbon source conditions. The influence of influent carbon/nitrogen ratio (C/N) on the denitrification and electricity-generation performance was explored. Although the increase of carbon source simultaneously improved chemical oxygen demand (COD), ammonia (NH4+-N), nitrate (NO3−-N) and TN removal, the power generation during the carbon source adjustment showed low relation with the variation of influent COD in the range of 40–120 mg/L. CW was more dependent on carbon sources, and the addition of bioelectrochemical systems into MFC-CW could reduce the dependence of nitrogen removal on carbon sources, especially under low carbon source conditions. These findings offer valuable insights into the potential applications of MFC-CW for tail water treatment, and its parameters for utilization in real CWs should be explored in future studies.