Regulation of the ambient conditions for improving heavy metals removal from tanning leather industry waste water by Aspergillus candidus

Abstract

In the present study, the whole fungal mycelia of Aspergillus candidus, showed the highest capacity for the removal of heavy metals: Pb +2 , Cu +2 , Fe +3 , Mn +2 , Cr +6 and Sr +2 from wastewater effluent of tanning leather industry, compared with the fungal pellets. Maximum biosorption capacity of metals was obtained after using 6 days old biomass and when the process was carried out at 28°C. Heavy metals sorption was observed at a wide pH range of the wastewater and particularly increased at slight acidic condition (pH 6) for sorption of Pb +2 and Cu +2 . However, sorption of Fe +3 , Mn +2 , Cr +6 and Sr +2 was stimulated after adjusting the pH of the waste water at the alkaline conditions (pH 8 for Fe 3+ and Mn 2+ , and 10 for Cr 6+ and Sr 2+ ), specially for the last two metals. The results confirm that, the dead biomass of A. candidus offered a great potential as abiosorbent over the living one.