Cr(VI) remediation in groundwater aquifer media using natural organic matter as carbon source
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Date
Authors
Mtimunye, Phalazane Johanna
Lutsinge Nembudani, Tshilidzi Bridget
Molokwane, Pulane Elsie
Chirwa, Evans M.N.
Journal Title
Journal ISSN
Volume Title
Publisher
The Italian Association of Chemical Engineering
Abstract
Cr(VI) is toxic to biological systems due to its strong oxidizing potential. However, some microorganisms
possess mechanisms that enable them to reduce the toxic of chromium [Cr(VI)] to the less toxic trivalent state
[Cr(III)] either as a survival mechanism aimed at reducing toxicity around the cell or as a means of deriving
metabolic energy for cell growth. Although Cr(VI) can be reduced by algae, fungi and phyto- and zooplanktons,
bacteria have been demonstrated to be the most efficient Cr(VI) reducing agents. Bacteria can reduce Cr(VI) to
Cr(III) either aerobically or anaerobically through a variety of biochemical pathways.
In this study, a culture comprising of mostly Bacilli sp. and Enterococcus sp. achieved high levels of Cr(VI)
removal in a continuous flow process under near anaerobic conditions. Up to 93 % removal was obtained under
a continuous feed of 40 to 60 mg/L after operation for 45 days. No additional nutrients and carbon sources were
added to the feed water as it was assumed that organic compounds produced by decaying roots and organic
matter in the soil could serve as carbon sources.
Organics in the soil were characterized using the HPLC, TOC Analyser and GC-MS and were determined to be
mostly comprised of breakdown compounds of humic acid. The study demonstrated the feasibility of in situ
bioremediation of Cr(VI) contaminated sites using selected cultures of Cr(VI) reducing bacteria while avoiding
secondary pollution from additional nutrients.
Description
Keywords
Chromium compounds, Survival mechanisms, Oxidizing potentials, Natural organic matters, Groundwater aquiferIn-situ bioremediation, Continuous-flow process, Biochemical pathway, Anaerobic conditions, Reducing agents, Organic compounds, Organic carbon, Nutrients, Groundwater resources, Bioremediation, Biological materials, Biogeochemistry, Bacteria, Aquifers
Sustainable Development Goals
Citation
Mtimunye P.J., Lutsinge T.B., Molokwane P.E., Chirwa E.M.N., 2017, Cr(vi) remediation in groundwater aquifer
media using natural organic matter as carbon source, Chemical Engineering Transactions, 61, 1831-1836 DOI:10.3303/CET1761303.