Biosorption of Cadmium from Aqueous Solutions Using A local Fungus Aspergillus cristatus (Glaucus Group)

Abstract

Cadmium (Cd) (II) resistant strain of a marine fungus, named Aspergillus cristatus was isolated from heavy metals polluted area in the Mediterranean Sea, Alexandria, Egypt during autumn, 2009. It could tolerate up to 100 mg l^–1. Optimization of culture conditions for production of fungal biomass fortifying maximum Cd (II) removal was done by applying Placket Burman experimental design. Under optimized culture conditions, metal uptake was (82%) achieved in a medium predicted to contain (gl^-1): glucose, 5; yeast extract, 1; KH₂PO₄, 4.00; (NH₄)₂SO₄, 4; MgSO₄, 0.75; CaCl₂.H₂O, 0.2 and inoculums size, 6%. A verification experiment was applied. Results show that the metal uptake increased by about 1.86 fold for optimized medium. The increase in the pH value from 3 to 6 led to an increase in the Cd (II) uptake which reached the maximum level at pH 6. The biosorption equilibrium time was 4 h. Sorption isotherms follow the typical Langmuir adsorption pattern. Living biomass was more efficient for Cd (II) uptake compared to its dried biomass. A successful trial showed good applicability of the marine fungal isolate to remove 98.1% of Cd (II), in the waste effluent of El- Nesr Varta Company for Batteries after 2 h of contact. The free living fungus succeeds to remove Cd (II) more than the luffa adsorbed fungal biomass from the waste effluent. These quantitative biosorption and accumulation capacities demonstrate the potential application of marine A. cristatus for the bioremediation of Cd (II) from water systems.

Key words: Aspergillus cristatus, cadmium, experimental design.