Remediation of lead, zinc and cadmium contaminated soil in the Celje area

Project co-ordinator: Marko Zupan, M. Sc.

Several areas in Slovenia are critically polluted by toxic metals, such as Cd, Pb, Zn and Hg (Celje, Mežica, Idrija…). The proposed project will be focused on the remediation of soils contaminated by lead, zinc and cadmium in the area of Celje, where more than 6000 ha of land, of which 2200 ha are used for agriculture, is heavily polluted (up to 600 mg/kg Pb, 3010 mg/kg, Zn, 20 mg/kg Cd).

Soil remediation methods can be grouped into “harsh” techniques that efficiently alleviate the risk but destroy soil structure and fertility, and “gentle” techniques that preserve or restore soil fertility. Gentle techniques are associated with addition of contaminant binding agents, liming (contaminants are constrained, but not removed from the soil) and phytoextraction. Soil washing by chelating agents (chelators) could also qualify as gentle technique, especially if the extraction is done via on site heap-leaching and not by extracting a soil slurry in a closed reactor. For preservation of the soil as a non-renewable natural resource it is important to use gentle techniques for remediation, especially if large areas of agricultural land are polluted.

In the proposed project, most of the “gentle” remediation techniques will be tested: solidification/stabilisation, ecoremediation, vitrification leaching and phytoextraction. A database on soil pollution parameters in the Municipality of Celje will be established, including environmental risk assessment resulting from the bioavailability of metals. Laboratory simulations of known remediation methods will be performed, a mathematical relationship between soil characteristics and metal bioavailability will be determined and a protocol of instructions for use of bioavailability tests will be elaborated.