Comparative study on chromium (VI) removal by dead and living fungal biomass of Aspergillus niger sp.

The removal of hexavalent chromium from aqueous solutions was studied by dead and live biomass of Aspergillus niger isolated from pistachio shell. Different concentrations of Cr (VI) in the range of 50 to 800 mg/l was investigated for Cr(VI) removal by dead and living fungi and theirefficiencies was compared. The living biomass in concentration of 5 g dry cell/l could remove97% of Cr(VI) ions from aqueous solutions up to 400 mg /l of Cr(VI) concentration at 30 °C andpH 7 within 48 h. But, the removal efficiency was decreased at initial chromium concentrations above 400 mg/l and was reduced to 6% at 600 mg/l of Cr(VI). However, the dead biomass could almost remove 100% of Cr(VI) ions from an aqueous solution of 400 mg. l−1 of Cr (VI) at 45 °Cand pH 3 within 24 h. The removal efficiency by dead biomass was still high at higher concentrations of Cr(VI) up to 800 mg/l. But, the results showed than at lower concentrations of Cr (VI) less than 250 mg/l, the living biomass were much more effective than the dead biomass.This indicates that at low concentration of Cr (VI) the biological treatment with living biomass of Aspergillus niger is a good choice and at higher concentrations, the dead biomass would be more suitable in Cr (VI) removal.

Keywords:

Chromium (VI) , Removal , Living biomass , Dead biomass , Aspergillus niger