Comparison of two filter materials for the removal of phosphate and heavy metals from traffic area runoff

Abstract

Decentralized stormwater treatment systems for runoff from traffic areas are used for the retention of solids, organic substances such as total petroleum hydrocarbons, and heavy metals. Furthermore, a removal of nutrients such as phosphorus is required at several sites for water protection. Specialized filter materials can be used for the simultaneous removal of different substances. Two of these filter materials, granular ferric hydroxide (GFH) and a newly developed calcium silicate, were evaluated in the lab regarding the removal of copper, nickel, zinc, and orthophosphate by batch and column experiments. In addition, the properties of calcium silicate and its removal efficiencies were determined under varying boundary conditions (influent concentrations and contact times). As a result, both filter materials are suitable to treat the tested substances. However, additional lab and field experiments must be performed to quantify other influences on the removal.