Removal of radioactive cesium from an aqueous solution via bioaccumulation by microalgae and magnetic separation

摘要

We evaluated the potential sequestration of cesium (Cssup+/sup) by microalgae under heterotrophic growth conditions in an attempt to ultimately develop a system for treatment of radioactive wastewater. Thus, we examined the effects of initial Cssup+/sup concentration (100-500?μM), pH (5-9), Ksup+/sup and Nasup+/sup concentrations (0-20?mg/L), and different organic carbon sources (acetate, glycerol, glucose) on Cssup+/sup removal. Our initial comparison of nine microalgae indicated that Desmodesmus armatus SCK had removed the most Cssup+/sup under various environmental conditions. Addition of organic substrates significantly enhanced Cssup+/sup uptake by D. armatus, even in the presence of a competitive cation (Ksup+/sup). We also applied magnetic nanoparticles coated with a cationic polymer (polyethylenimine) to separate sup137/supCs-containing microalgal biomass under a magnetic field. Our technique of combining bioaccumulation and magnetic separation successfully removed more than 90% of the radioactive sup137/supCs from an aqueous medium. These results clearly demonstrate that the method described here is a promising bioremediation technique for treatment of radioactive liquid waste.