Research on the Construction of Constructed Wetland System for Synergistic Purification of Initial Rainwater and Tailwater from Sewage Treatment Plants

To further reduce the discharge of nitrogen, phosphorus and other nutrients in initial rainwater and tailwater from sewage treatment plants, this study coupled bioretention facilities with constructed wetlands using pyrite as the substrate, and established a constructed wetland system for their synergistic purification.The results showed that the constructed wetland could be rapidly established during the start-up phase and achieve a stable pollutant removal efficiency. In the dry season, the concentrations of NH₄⁺-N, TN and TP in the effluent were 0.04±0.07 mg/L, 2.01±1.22 mg/L and 0.12±0.07 mg/L, respectively. In the wet season, the concentrations of NH₄⁺-N, TN and TP in the effluent were 0.89±0.33 mg/L, 1.22±0.24 mg/L and 0.09±0.01 mg/L, respectively. All the above indices were superior to the requirements of Class Ⅳ water criteria (non-lake and non-reservoir) specified in Environmental Quality Standards for Surface Water (GB 3838-2002).