Solubilization of Pu-239 in Low-level Radioactive Contaminated Soil by the Addition of Microbial Leaching Solution of Acidithiobacillus Ferooxidans

Researches on microbial solubilization of traces of radionuclide plutonium in contaminated soil with Acidithiobacillus ferooxidans were conducted. When A. ferooxidans was cultured in medium containing sulfur and iron, 92.93% of the Pu-239 in solution was removed during bioleaching. In addition, the changes of pH value, concentrations of Fe2+, Pu-239, organic matter, nitrogen and phosphorus were periodically analyzed. The results showed that bioleaching affected the combination forms of Pu-239 existing in the soil. The percentage of Pu-239 exits in exchangeable state increased significantly because the carbonate state, iron and manganese oxidation state and residual state transformed into exchangeable state during bioleaching. At the same time, the percentage of organic state kept steadily. The changes of form into exchangeable state which can improve the leaching rate effectively. The results showed that the bioleaching process can be used to remove Pu-239 from contaminated soil.