Treatment of urban and highway stormwater runoff for dissolved and colloidal pollutants

The design of three stormwater treatment facilities, aiming at implementing and demonstrating technologies that efficiently reduce diffuse urban pollutant loads onto receiving waters is presented. The designs aim at reducing not only particulates, but also dissolved pollutants and pollutants associated with colloids. Unit operations that are efficient in this respect are discussed. Different technologies for extended treatment of stormwater runoff are applied in the design of each facility: One facility applies iron enrichment of bottom sediments; another applies the addition of aluminium salts to the incoming stormwater; and the last facility applies fixed media filters. Laboratory results regarding the removal of phosphorus by fixed media are presented.