The Need for Advanced Treatment of Storm-Water Run-Off from Separate Sewer Systems

A wide spectrum of anthropogenic pollutants exists in surface run-off resulting from precipitation. These are mainly organic micropollutants and heavy metals, which are transported in association with finer suspended solids. Conventional treatment methods for storm-water run-off using sedimentation alone are not sufficient for reducing the input of particulate materials with adsorbed contaminants to natural waters. Chemical precipitation/coagulation is effective in produ- cing separable aggregates and phase separation using flotation or cyclone and vortex separators can then be applied to remove them from storm-water.