Abstract
The present study deals with the determination of the iron oxidation rate (IOR) of Acidithiobacillus ferrooxidans in the presence of various heavy metal ions. Initially, the IOR of this particular strain was enhanced to 718 mg L–1 h–1 by several sets of subculturing of the whole biomass in fresh medium. In the process, the bacterial regeneration time was determined to be 3˙7 h. The effect of various heavy metal ions (Hg, Ag and Pb) on IOR of this active strain was studied and the reaction kinetics in the presence of various concentrations of heavy metal ions in the solution has been determined. The tolerance index of the active culture to various heavy metals has also been established. The tolerance index in the presence of 700 mg L–1 Pb, 50 mg L–1 Ag and 0˙1 mg L–1 Hg was 5˙1, 5˙1 and 11˙9 respectively. Therefore, it was concluded that Hg ion rendered maximum toxicity to the bacterial strains followed by Ag and Pb. By statistical interpretation of the observed data, it was possible to formulate a very significant correlation between all the sets of experiments that were conducted in the presence and absence of metal ions.
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