Abstract

Mining operations in Sukinda and Baula-Nuasahi region of Orissa, India have led to the generation of a huge amount of overburden with considerable amount of chromium. Weathering of chromium by the natural agencies often contaminates the water sources of the region. Microbes indigenous to this environment having the potential of accumulating metals could be employed for removal as well as detoxification of heavy metals. Chromium resistant fungi were isolated and purified from the chromite mining environment and evaluated for their potential to biosorb hexavalent chromium using dried fungal biomass. Aspergillus niger NUA101, the best sorbent removed about 17.58 mg Cr(VI)/g biomass from a solution containing 25 mg Cr(VI)/l. The sorption capacity of the isolate was standardized following Langmuir and Freundlich adsorption isotherm models and the process was optimized for several standard parameters like, initial metal ion concentration, sorbet concentration, incubation temperature, pH, presence of additional cations and chemical treatment of the biomass. Under optimized conditions, A. niger mycellial mass appeared to be effective in removing Cr(VI) from aqueous solution.

Key words: Hexavalent chromium, fungal biosorption, Aspergillus niger NUA101, chromite mining overburden, heavy metal detoxification.