Bioleaching of Pb-Zn ore by Moderate Thermophilic Chemolithotrophic Bacteria

Pb-Zn ore bioleaching performances of pure un-adapted and metal ion-adapted cultures of Sulfobacillus thermosulfidooxidans as well as its consortium with acidophilic hetertrotroph (6A1TSB) were analyzed. Nearly 58% of Zn was solubilized form the ore with mixed consortium at the rate of 3.0 mg L-1h-1, whereas with pure adapted and un-adapted it was 55% and 40% respectively, in 360 h with bioleaching rates of 2.5 mg L-1h-1 and 1.8 mg L-1h-1. Similarly maximum lead dissolution (57%) was obtained with mixed consortium, while pure adapted and un-adapted cultures leached out 52 % and 26% Pb, respectively. The leaching rates of lead with mixed consortium, pure adapted and un-adapted cultures were 1.25 mgL-1h-1, 1.0 mg L-1h-1and 0.439 mgL-1h-1 respectively. Cell dry biomass production rates during bioleaching also followed the same pattern, with the mixed consortium having the highest biomass production rate i.e. 0.0030 gL-1h-1 and same pattern was observed in case of rate of iron solublization.