Chryseomonas luteola TEM 05 cells were entrapped both in alginate and chitosan coated alginate beads. Biosorption of metal ions on alginate beads was investigated by using a batch stirred system at pH 6.0, 25 degrees C, in initial metal concentration of 1.92 mM of Cr6+ 0.89 MM Cd2+ and 1.69 mM Co2+. Then, a process of competitive biosorption of these metal ions was described and compared to single metal ion adsorption in solution. The apparent equilibrium biosorption was reached within the 180 min of contact for all metals. Although the competitive biosorption capacities of the beads for all metal ions were lower than those of single conditions, Cd2+ biosorption on alginate and alginate-chitosan beads did not change significantly. (C) 2007 Elsevier B.V. All rights reserved.