Cadmium and cobalt adsorption from aqueous solution onto calcium alginate, sodium alginate with an extracellular polysaccharide (EPS) produced by the activated sludge bacterium Chryseomonas luteola TEM05 and immobilized C luteola TEM05 was studied. In addition, solutions containing both of these ions were prepared and partial competitive adsorption of these mixtures was investigated. Metal adsorption onto gel beads was carried out at pH 6.0 and 25 degrees C. The maximum adsorption capacities determined by fitting Langmuir isotherms to the data for calcium alginate, calcium alginate + EPS, calcium alginate + C luteola TEM05 and calcium alginate + EPS + C luteola TEM05 were 45.87, 55.25, 49.26, 51.81 mg g(-1) for Co(II) and 52.91, 64.10, 62.5, 61.73 mg g for Cd(II), respectively. The biosorption capacity of the carrier for both metal ions together in competition was lower than those obtained when each was present alone. (c) 2005 Elsevier Ltd. All rights reserved.