Removal of hexavalent chromium from wastewater using microorganisms adapted to Chromium-Rich Media

Introduction: Global aquifer contamination problems are a cause for concern and require effective remediation methods to minimize the environmental impact generated by industrial and domestic dumping. Objective: In the present study, the ability to remove Cr⁶⁺ from bacteria and yeasts adapted to high concentrations of this metal was determined. Methods: Removal tests were carried out in BHI culture medium and in residual water to which potassium dichromate (K₂Cr₂O₇) was added. Results: Bacteria and yeasts isolated and adapted to Cr⁶⁺ were shown to be reductive of this metal. The bacterial isolates Raoultella sp, Serratia sp and Klebsiella sp presented higher reduction of Cr⁶⁺ in residual water (AR) reaching 100% reduction of chromium in 30 hours, these three isolates were highlighted by their ability to reduce Cr⁶⁺ in both culture medium As in residual water at all concentrations of K₂Cr₂O₇ evaluated. The yeast isolates Candida Tropicalis, Candida Famata and Cryptococus neoformans did not present significant differences with the control in the reduction test of the metal in RA with different concentrations of Cr⁶⁺. Conclusions: The ability of Cr⁶⁺ reduction, as well as the bacterial growth in high conditions of this metal, allow to propose Klebsiella sp, Raoultella sp, and Serratia sp as promising microorganisms for the bioremediation of sites contaminated with Cr⁶⁺ in real scale.

Keywords: Waste water, microorganisms, heavy metals, hexavalent chromium

https://www.revistaaccb.org/r/index.php/accb/article/view/140