Combined neutralization-adsorption system for the disposal of hydrothermally altered excavated rock producing acidic leachate with hazardous elements

► Mechanisms of hazardous element release include dissolution and pyrite oxidation. ► Volcanic ash sampled near the site was capable of adsorbing As(V), Pb, Cu and Zn. ► The combined system effectively minimized the release of As, Pb, Cu and Zn. ► Immobilization of the toxic elements occurred via co-precipitation and adsorption.