Contamination of soils due to the release of effluents or deposition of wastes
containing hexavalent chromium has been arising serious environmental problems.
Therefore, the development of cost effectiveness but also ecological cleaning techniques is
a matter of great concern among the scientific community. Bioremediation is attracting
more and more attention due to its efficiency, low impact in the ecosystems and low cost.
In particular, this study approaches a bioleaching technique using an Acidithiobacillus
thiooxidans DSM504 pure culture to clean a soil contaminated with hexavalent
chromium. Eight batch tests were performed in order to evaluate the effect of combined
parameters: operational temperature (26ºC and Troom), hexavalent chromium
concentration (50 mg kg-1 and 100 mg kg-1) and pH of the contaminant solution (2 and
pHfree). The bioleaching technique herein exposed presented removal values between
33.3% and 83.3%, undergoing higher deviations due to changes on the contamination pH.
Generally, it was more efficient when applied to soils contaminated with acid solutions.
The lowest and highest values were both observed for operational temperatures of 26ºC
and hexavalent chromium concentrations of 50 mg kg-1. Moreover, the highest value was
observed for the soil contaminated with a hexavalent chromium solution of pH 2
