Title: Characterisation of Cr(VI) generation in chromite mine overburden and its toxic impact on microbial diversity

Authors: Biswaranjan Dhal; Banshi Dhar Pandey

Addresses: CSIR-National Metallurgical Laboratory, Metal Extraction and Forming Division, Jamshedpur-831007, India ' CSIR-National Metallurgical Laboratory, Metal Extraction and Forming Division, Jamshedpur-831007, India

Abstract: This study aims at the assessment of the environmental status and microbial diversity prevailing in the overburden soil of South Kaliapani chromite mine area, Sukinda, India. It is found that the overburden soils/dumps are dry and semi-hard rocky material, and contain low nutrients (N, P, K and organic carbon). Major metal components present in the dump soils are (wt%): 2-24 Cr, 33-58 Fe, 0.4-0.5 Mn, 0.5-1.2 Ni, and 0.02-0.04 Co. The overburden soils have low microbial population (bacteria 7 − 29 × 10⁵ colony forming units (cfu) g⁻¹ and fungi 3 − 9 × 10⁵ cfu g⁻¹) due to the presence of Cr(VI), a toxic pollutant. The water samples contained Cr(VI) (0.97 mg L⁻¹) and Co (0.345 mg L⁻¹), which were higher than the permissible limits. Oxidation of Cr(III) of the chromite mineral present in the chromite ore overburden (COB) by manganese oxides is indicated by SEM-EDS studies which causes Cr(VI) pollution and affects microbial diversity.

Keywords: opencast chromite mining; hexavalent chromium; chromite ore overburden; COB; mine drainage; characterisation; PI; Cr(VI) toxicity; oxidation of Cr(III) by MnO₂; chromium(VI) toxicity by oxidation of Cr(III) with MnO₂; microbial diversity; Cr(VI) tolerant microbes.

DOI: 10.1504/IJEWM.2017.090057

International Journal of Environment and Waste Management, 2017 Vol.20 No.4, pp.324 - 345

Received: 17 Aug 2017
Accepted: 16 Jan 2018
Published online: 27 Feb 2018 *

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