The effects of <Emphasis Type="Italic">Acidithiobacillus ferrooxidans</Emphasis> on the leaching of cobalt and strontium adsorbed onto soil particles |
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Authors: | Hyun-Sung Park Jong-Un Lee Jae-Woo Ahn |
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Institution: | (1) Microbial Geochemistry Lab, Department of Geosystem Engineering, Chonnam National University, Gwangju, 500-757, Korea;(2) Department of Advanced Materials Science and Engineering, Daejin University, Pocheon, 487-711, Korea |
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Abstract: | Bioleaching from soil artificially contaminated with analogues of radionuclides, Co and Sr, was carried out using a Fe-oxidizing
bacterium, Acidithiobacillus ferrooxidans. Due to bacterial metabolism, the pH and dissolved Fe3+ concentration in a biotic slurry decreased and increased respectively, over time, but the concentrations of Co and Sr extracted
from the soil showed no significant enhancement compared with those under abiotic control. In both cases, Co and Sr were leached
from the soil during the initial period of the experiment, due to the initially low solution pH of 2.0, and the dissolved
concentrations remained almost constant for the duration of the experiment (300 h). Since oxidation of Fe2+ by A. ferrooxidans led to the production of Fe precipitates and colloidal suspensions, the Co and Sr extracted into solution were most likely
re-adsorbed onto the Fe solids. Also, A. ferrooxidans, without an external supply of Fe2+, extracted almost equal or greater amounts of Co and Sr from the soil than when Fe2+ was supplied. Under the same leaching conditions, the extent of Sr removal was much lower than that of Co. On the contrary
to the high efficiency of microbial metal leaching in biohydrometallurgy for low-graded sulfide ores, which has been widely
documented, conventional bioleaching techniques with A. ferrooxidans supplied with enough Fe2+ showed low efficiency for the removal of radionuclides loosely bound onto soil particle surfaces. |
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Keywords: | Bioleaching Radionuclides Cobalt Strontium Acidithiobacillus ferrooxidans Soil |
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