Reduction of pollution loads based on sewage treatment projects around a lake: a case study on Erhai Lake

Abstract Erhai Lake is a highland freshwater lake in Dali, China. Rapid tourism development has generated large amounts of pollutants. Since 2015, six wastewater treatment plants (WWTPs) have been built to treat collected through sewage interception projects. In this study, reductions the pollution load from different sources were evaluated by considering effects groundwater leakage, microbial degradation, and rainfall-runoff. The results showed that systems reduced chemical oxygen demand (COD), total nitrogen (TN), phosphorus (TP) loads 85, 83, 85%, respectively. Discharge characteristics low concentration domestic discharge, tourist high livestock wastewater. Due level, there infiltration influent water WWTPs, which dilutes pollutant and, therefore, lower efficiency. Further tailwater also discharged into as well COD TN 10.25 22.90%, indicate sewer network system primary target be addressed future developments.