Reduction of hexavalent chromium by Rhizopus Oryzae

Abstract

The ability of Rhizopus oryzae to reduce Cr⁶⁺ was evaluated in batch microcosms. The optimum pH of R. oryzae growth was between 6.0 and 7.0. The maximum chromium reduction efficiency of 91.15% and biomass growth was achieved at a pH of 7, temperature of 37°C, with an initial Cr⁶⁺ concentration of 400 ppm and incubation period of 72 h. Monod and Haldane models were used to describe the chromium reduction data and the specific growth rate constant value was calculated as 0.082 and the reduction rate was found to be highest at 400 mg Cr⁶⁺ /l. The high removal of chromate by R. oryzae indicates a feasible, economical technique for chromate removal from industrial wastewater effluents.

Key words: Hexavalent chromium, Rhizopus Oryzae, leather tanning, Monod and Haldane models.