A laboratory bioremediation process to treat heavy metal contaminated soils

Heavy metals and radionuclides are major contaminants found at many industrial sites and are frequently found in the presence of organic contaminants. A laboratory process has been developed to biologically treat heavy metal contaminated soils which can be adapted to treat heavy metal and organic co-contaminated soils. Heavy metals of interest include; Cd, Cr, Cu, Co, Ni, Pb, Zn and Mn. Soil columns were set-up from which the selected heavy metals were effectively mobilised by optimizing the activities of indigenous soil microbes. Soluble metals present in the leachate were treated and precipitated in a SRB bioreactor downstream. Secondary waste streams containing soluble and gaseous H2S were treated after the bioreactor stage. This laboratory process generated low volume secondary wastes such that the final precipitated metal waste represented a >99% volume reduction of the orginal waste.