Study on the effect and influencing factors of nitrogen and phosphorus removal from rural wastewater by electrochemically enhanced constructed wetland

The increasing discharge of rural domestic sewage presents significant environmental challenges. The effectiveness of electrochemically enhanced constructed wetlands (CW), specifically vertical flow systems were investigated for removing nitrogen and phosphorus from rural wastewater. Factors including hydraulic retention times (HRTs), current intensities, and carbon-to-nitrogen (C/N) ratios were studied to evaluate system performance. Optimal nitrogen and phosphorus removal was achieved at an HRT of 24 hr and current intensity of 15 mA. Specifically, the three-dimensional electrochemically enhanced constructed wetland (3DE-BVFCW) system achieved removal rates of 90.40% for total phosphorus (TP), 93.82% for nitrate nitrogen (NO3 --N), and 76.59% for total nitrogen (TN). While higher current intensities initially enhanced nutrient removal, excessively high intensities inhibited these processes. The optimal C/N ratio was found to be 3:1. Additionally, the incorporation of granular activated carbon in the 3DE-BVFCW system enhanced electron flow, leading to superior nutrient removal performance. Microbial community analysis further supported these findings, revealing that key microbial groups, such as <i>Proteobacteria</i> and <i>Actinobacteria</i>, exhibited higher relative abundance in the 3DE-BVFCW system under optimal conditions. These microbes are instrumental in nitrogen and phosphorus removal, particularly through denitrification. Integrating electrochemical technology with constructed wetlands offers a promising solution for the sustainable treatment of rural wastewater.