Native fungal isolates for biosorption of Cr(VI): A potential approach for treatment of chromite mine drainage

Abstract

Chromium (VI) resistant fungal species were isolated from the chromite mine drainage often containing 2-5 14 L-1 Cr(VI) and used for bio-sorption of hexavalent chromium from chromite mine drainage. Two fungal species designated as SWF-1 (A. niger) and SWF-2 (A. fumigatus), were identified by standard biochemical and microscopic methods. Sorption parameters for Cr(VI) were optimized with the biomass (live) of the A. fumigatus while varying pH, biomass ratio, temperature, contact time and Cr(VI) concentration. It was found that A. fumigatus exhibited maximum sorption at 5.5 pH; 35°C temperature with 1% sorbent/solution (w/v) ratio at 100 rpm. Under the optimized conditions, the SWF-2 showed high metal sorption (more than 96% in 120 h) from an aqueous solution of 50 mg L' Cr(VI). The maximum bio-sorption capacity was found to be 48.6 mg with dried (live) biomass of SWF-2 in 120 h. The chromium sorption data showed good fit to the Freundlich isotherms indicating strong chemical interaction of the metal ion with the functional groups of the fungal cell wall. The present study demonstrated that the isolated Aspergillus sp. have potential application to remediate the hexavalent chromium from mine drainage and industrial effluents.