The bioleaching assessment for nuclear power plant-soil contaminated with Co and Cs using A.Thiooxidans sp

Abstract

We analyzed the tolerance of sulfur-oxidizing bacteria to Co and Cs exposure and gamma-ray irradiation, and evaluated the feasibility of bioleaching to remove radionuclides from contaminated soil. The soil samples were collected in the vicinity of a nuclear power plant in the Republic of Korea and artificially contaminated with Co and Cs to mimic accidental exposure (initial concentration of Co and Cs were 253 mg/kg and 307 mg/kg, respectively). The applied bacteria were identified as Acidithiobacillus thiooxidans with a 95 % similarity of DNA sequence. The bacteria enabled sulfur oxidation at Co concentration of less than 50 mg/L and irrespective of Cs concentration. In addition, the bacteria showed tolerance to 400 Gy gamma-ray irradiation. Overall, the Bioleaching process removed 98 % of Co and 96 % of Cs from the artificially contaminated soil and, compared to control samples, approximately doubled the removal efficiency. These results demonstrate that bioleaching by sulfur-oxidizing bacteria has potential as a remediation strategy for radionuclide contaminated soils.