Use of the microalga Scenedesmus obliquus to remove cadmium cations from aqueous solutions

The ability of a wild strain of Scenedesmus obliquus, isolated from a heavy metal-contaminated environment, to remove Cd2+ from aqueous solutions was studied at several initial concentrations. Viable biomass removed metal to a maximum extent of 11.4 mg(Cd)/g at 1 mg(Cd)/l, with most Cd2+ being adsorbed onto the cell surface. A commercially available strain (ACOI 598) of the same microalga species was also exposed to the same Cd concentrations, and similar results were obtained for the maximum extent of metal removal. Heat-inactivated cells removed a maximum of 6.04 mg(Cd)/g at 0.5 mg(Cd)/l. The highest extent of metal removal, analyzed at various pH values, was 0.09 mg(Cd)/g at pH 7.0. Both strains of the microalga tested have proven effective in removing a toxic heavy metal from aqueous solutions, hence supporting their choice for bioremediation strategies of industrial effluents.