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 the
environmental goal about a non-toxic environment adopted by the Swedish Parliament, the
leachate must be treated before being discharged into a nearby surface or groundwater body.
There are several technical treatment options based on chemical, biological or physical
processes. Examples of these techniques are the SBR technique, oxidation and membrane
filtration. These treatment methods are not always suitable at all landfill sites due to
economical and/or technical constraints. Other treatment methods have therefore attracted
attention. These methods, often natural based such as constructed wetland systems, are more
adapted to small landfill sites where high-tech and cost-demanding alternatives are not an
option. One natural based method that has attracted attention for leachate treatment in recent
years is the filter technique. It is based on the passage of a polluted water flow through a filter
media with properties suitable for retention of heavy metals or other pollutants. A large
number of different filter materials have been investigated with regard to their metal sorption
capacity. The majority of these studies have been carried out in laboratory experiments of
different kinds. Industrial by-products such as blast furnace slag and pine bark are filter
materials that have been considered interesting for metal removal from landfill leachate. A
series of laboratory experiments carried out as batch tests have therefore been conducted in
order to learn more about the potential of these filter materials to remove heavy metals from
landfill leachate.