Sorption filters for removal of heavy metals from landfill leachate

The aim of this study was to find sorption filters with a capacity to remove heavy metals from landfill leachate. Initially a batch test was performed with granular activated carbon, CAP meal derived from animal bones, iron fines, a non-metallic part of bottom ash from a municipal solid waste incineration plant, metal residues from the same bottom ash, lime stone and peat. Activated carbon, CAP meal and iron fines did best and were tested in a continuous test. Activated carbon had the best ability to remove metals and the best flow properties, but released As. CAP meal had the worst flow properties and released large amount of organic matter and nutrients. The iron fines used here released many metals initially, but then achieved a net removal of most but not all. Leaching of unwanted substances can be a problem when using reactive filters and the behaviour of the filter material can depend on the leachate treated. Therefore the combination should always be thoroughly tested before being implemented.