Graphical AbstractVerifiedEnhanced Treatment of Reclaimed Water Using Functional Manganese-Sand Media in Constructed Wetlands
Reclaimed water serves as an alternative water source for replenishing natural water bodies, yet residual pollutants pose ecological risks. A pilot-scale hybrid vertical flow constructed wetland filled with manganese ore sand, quartz sand, and cobblestones was operated for approximately 140 days to assess nutrient and organic matter removal, ecotoxicity, and the suitability of manganese sand as a functional medium. Influent concentrations were up to 0.4 mg/L ammonia, 0.2 mg/L phosphate, 8 mg/L nitrate, and 30 mg/L COD. After 2–3 months of operation, ammonia and phosphate removal efficiencies exceeded 90% and 80%, respectively. Average reductions for nitrate and COD were 0.67 mg/L and 4.2 mg/L. Manganese sand enhanced organic decomposition, reducing maximum 3D fluorescence intensity by 26%, humic substances by 48%, UV254 by 38%, and achieving 70.8% removal of four target antibiotics. Purified water exhibited no significant genotoxicity, with micronucleus rates approaching tap water levels, and non-concentrated samples showed no acute biotoxicity. However, concentrated samples displayed acute toxicity, suggesting different causative pollutants for genotoxicity and acute toxicity. The study supports manganese sand as an effective medium for improving reclaimed water quality and controlling ecological risks.
