Immobilized and dried powdered Trametes versicolor and Phanerochaete chrysosporium basidio of spores were used for the recovery of uranium from aqueous solutions. The biosorption of UO22+ ions by the carboxymethylcellulose and immobilized and heat-killed fungal mycelia of T versicolor and P chrysosporium was studied from aqueous solutions in the concentration range of 100-1000 mg/l. The biosorption of UO22+ ions by the carboxymethylcellulose and immobilized and dried powdered preparations increased as the initial concentration of uranium ions increased in the medium. Maximum biosorption capacities for immobilized and dried powdered fungal mycelia of T versicolor and chrysosporium was found as 309.1 mg UO22+ /g and 158.0 mg UO22+ /g, respectively; whereas the of UO22+ ions adsorbed on the plain carboxymethylcellulose beads was 29.2 mg/g. Biosorption equilibria were established in about 20 min and the correlation regression coefficients show that the adsorption process can be well-defined by Langmuir equation. The effect of pH was also investigated and the maximum adsorption UO22+ ions on the carboxymethylcellulose and both live and heat-inactivated immobilized fungal mycelia were observed at pH 4.5. The carboxymethylcellulose-fungus beads could be regenerated using 10 mM HCl, with up to 98% recovery. The biosorbents were used in five biosorption-desorption cycles and no considerable loss in the biosorption capacity was observed. For the synthetic wastewater samples, it was observed that immobilized and dried powdered fungal mycelia of T versicolor and P chrysosporium removed 91.8% and 66.8% of uranium ions, respectively. (C) 2003 Elsevier Science B.V. All rights reserved.