Filtration of storm water for metal reduction using natural filter substrates

摘要

In order to immobilise pollutants in storm water-such as heavy metals that are eitherrndissolved or bound to small particles-filter systems featuring various different filterrnsubstrates can be constructed to filtrate storm water. Two important parameters for the designrnand functioning of such a filter system include the load capacity and removal efficiency of thernmaterial used in the filter bed. These are essential considerations in the design of the filterrnitself. A sound knowledge of the operational and maintenance activities of these systems isrnalso necessary for achieving reliable treatment systems. This paper describes an experimentrnwhere storm water from a section of highway and surrounding roads has been filtratedrnthrough experimental columns filled with specially selected natural filter materials-calciumrnsilicate rock (opoka), zeolite and pine bark. Filtration was performed in a downward directionrnunder unsaturated conditions. The efficiency of copper and zinc removal of a number ofrncombinations of these filter substrates has been analysed. The average reduction of thesernmetals in filtrated storm water was around 63-81%, depending on the combination of metalrnand filter substrate.