The nitrogen-fixing cyanobacterium Anabaena sp. ATCC 33047, which generates substantial amounts of exopolysaccharide, was immobilized by entrapment within the reticulate network of polyurethane foam discs. The immobilized Anabaena sp. system has been investigated as a potential biosorbent for the removal of cadmium from aqueous solutions. The results showed that it was a highly fast process, with 80 % of the adsorption taking place in the first 10 min, reaching full equilibrium in about 50 min. Data analysis indicated that the behaviour of the system accurately fits to a monolayer adsorption model (Langmuir isotherm). The maximal biosorption capacity determined for the immobilized Anabaena sp. system was as high as 162 mg Cd (II) per gram dry biomass. The outstanding properties established for immobilized Anabaena sp. in polyurethane foam underline the relevance of such a system as an alternative to current treatments of variety effluents or wastewater contaminated with cadmium.

Peer reviewed