Best Management Practices to Reduce Phthalate and Nonylphenol Loads in Urban Runoff

Phthalates and nonylphenols, organic substances of widespread use, are believed to be ubiquitous in Swedish stormwater and urban sediments. Due to their reported hazardous properties, it is of great interest to identify effective best management practices (BMPs) to reduce the release of these substances to recipient waters. The stormwater-quality model SEWSYS was used to identify sources and quantify loads of phthalates and nonylphenols in two urban catchment areas. Based on the modelling results, BMPs were proposed, and their efficiencies evaluated. The SEWSYS simulations showed that discharges of phthalates and nonylphenols depend on catchment area characteristics: pollutants in a residential area originate mainly from building materials, whereas vehicles are the dominant source in a high-density traffic area. By replacing traditional building materials by phthalate and nonylphenol-free alternatives and by implementing congestion taxes to reduce traffic, the simulated pollutant loads could be reduced by more than 20 % in the high-density traffic area. However, discharges from many diffuse sources cannot entirely be stopped, and a structural BMP, e.g. a sedimentation pond, is essential to further decrease pollutant loads in urban runoff. This study shows that SEWSYS can be a useful tool for selecting and evaluating adequate BMPs to reduce stormwater contamination