Removal of chromium (III) from tannery wastewaters with acidophilic fungi

Abstract

Conventional methods for chromium removal from industrial effluents may be limited by technological or economical constraints, especially when they are applied to dilute metal solutions. Thus, biotechnological processes, which are efficient at low metal concentrations and require the use of fewer chemicals, may play an important role. The chromium recovery proposed here is based on the specific uptake of this metal by acidophilic fungi. Fifty acidophilic fungal isolates from the Río Tinto basin, an extreme acidic environment, were tested. Most of them were resistant to Cr(III) and Cr(VI) solutions at concentrations up to 10 mmol/L. The influence of different experimental conditions was evaluated (medium concentration, kinetics, requirement of induction etc.). Fungal isolate 143 was able to remove 63% of Cr(III) at 0.1 mmol/L, 74% at 1 mmol/L and 21% at 10 mmol/L. These are the best Cr(III)-fungal-uptake results at acidic pH described in the literature so far. It should be possible to use these acidophilic fungi, for example in tannery wastewater, as they can resist chromium concentrations and pH values found in these effluents (between 6.5-7.5 mmol/L Cr III and pH as low as 3-4)