Blast furnace slag and pine bark as potential filter media for metal sorption from landfill leachate

Abstract

Heavy metals are commonly occurring in landfill leachate and in order to achieve theenvironmental goal about a non-toxic environment adopted by the Swedish Parliament, theleachate must be treated before being discharged into a nearby surface or groundwater body.There are several technical treatment options based on chemical, biological or physicalprocesses. Examples of these techniques are the SBR technique, oxidation and membranefiltration. These treatment methods are not always suitable at all landfill sites due toeconomical and/or technical constraints. Other treatment methods have therefore attractedattention. These methods, often natural based such as constructed wetland systems, are moreadapted to small landfill sites where high-tech and cost-demanding alternatives are not anoption. One natural based method that has attracted attention for leachate treatment in recentyears is the filter technique. It is based on the passage of a polluted water flow through a filtermedia with properties suitable for retention of heavy metals or other pollutants. A largenumber of different filter materials have been investigated with regard to their metal sorptioncapacity. The majority of these studies have been carried out in laboratory experiments ofdifferent kinds. Industrial by-products such as blast furnace slag and pine bark are filtermaterials that have been considered interesting for metal removal from landfill leachate. Aseries of laboratory experiments carried out as batch tests have therefore been conducted inorder to learn more about the potential of these filter materials to remove heavy metals fromlandfill leachate.