Use of industrial residues for heavy metals immobilization in contaminated site remediation: a brief review

The increasing use of industrial residues for the remediation of landscapes contaminated with heavy metals diminishes the negative environmental impact of the contamination itself, reduces the demand for primary raw materials and minimizes the costs for the disposal of the residues. On the other hand, industrial residues often contain heavy metals themselves, which make their application for contaminated site remediation controversial. This study assembles and compares results of different investigations, such as laboratory tests, greenhouse tests and full-scale field tests, concerning heavy metals immobilization in soils all over the world. This review begins with an overview of the principles of immobilization and then focusses on two major groups of industrial residues: (i) residues from metallurgy (slags and red mud) and (ii) residues from thermal processes, i.e. incineration and pyrolysis. The feasibility of industrial residue applications in contaminated site remediation is presented exemplarily for the immobilization of arsenic, cadmium, cobalt, chromium, copper, manganese, nickel, lead and zinc. Red mud and steel slag additives show a high removal efficiency for specific heavy metals at contaminated field sites, whereas fly ash and biochar applications exhibit a high performance for various heavy metals uptake at laboratory scale, bearing a high potential for the extension to full-industrial scale. The latter materials may increase the soil pH, which favours the sorption of cationic heavy metals, but may decrease the sorption of hazardous oxyanions