Heavy metal immobilization using fly ash in soils contaminated by mine activity

Often the remedial measures required to clean up sites contaminated with heavy metals are so complex that their implementation becomes economically unsustainable. In these cases immobilization of the metal contaminants, by means of suitable soil amendments, is a promising and economically feasible technique for soil remediation. In this context, an experimental investigation has been carried out to assess the potential use of fly ash from coal-fired power stations for immobilizing the heavy metals contained in soils in a severely contaminated Italian mine site. Parallel experiments have been carried out in columns, one containing the soil as received, the other the soil mixed with fly-ash. The tests lasted for more than one year and the results obtained so far have shown that the heavy metal content of percolating waters can be drastically diminished when the soils are admixed with fly ash