CR(VI) REDUCTION IN PACKED-COLUMN MICROCOSM REACTORS USING CHROMIUM REDUCING MICROORGANISMS

Abstract

This research was the initial step towards the development of an in situ bioremediation process to contain the spread of a Cr(VI) plume in a groundwater aquifer at contaminated site in Brits, South Africa. South Africa holds about 72% percent of the world’s chromium resources the majority of which is mined in the North Eastern region of the country formally known as Transvaal. The remediation process was first observed in aquifer microcosms in which up to 50 mg/L was completely removed under a hydraulic loading of 0.304 cm 3 /h. The proposed in situ bioremediation process is expected to be more cost effective and less environmentally intrusive than the currently employed pump-and-treat method at the site. Microbial culture characterisation results showed a change in culture composition after 45 days of reactor operation, indicating Bacillus and Enterobacter species as the most dominant species in reactors that reduced Cr(VI) . The predominance of Bacillus and Enterobacter species was either due to resilience against toxicity or adaptation to the changing conditions in the reactor.