Biological uptake of precious and base metals from gold-process cyanide effluents

Abstract

The ability of different fungal species isolated from gold mines to uptake gold and other base metals like zinc, copper, iron and lead from gold-process cyanide effluents has been investigated. Under identical treatment conditions, different strains showed wide variations in their ability to take up gold and other base metals. Aspergillus terreus exhibited as high as 60% gold uptake. Almost complete removal of zinc was possible with different fungi and the yeast Saccharomyces cerevisiae. Metal uptake studied as a function of solution concentration showed higher gold uptake from dilute solutions. Studies with Aspergillus niger showed that gold uptake by living cells increased gradually with increase in contact time. Metal uptake capacities between killed and live cells have also been compared in different cases. Waste biomass ABM-1 from a fermentation industry has also been identified for its high gold uptake capacity. At 5% (W/v) solids, the ABM-1 efficiently removed up to 83% gold from the effluent solutions within 24 hours.