Trivalent and hexavalent chromium continuous biosorption was studied using residual brewer Saccharomyces cerevisiae immobilized in volcanic rock. The columns used in the process had a diameter of 4.5 cm and a length of 140 cm, working at an inlet flow rate of 15 mL/min. Breakthrough curves were used to study the yeast biosorption behavior in the process. The saturation time (t(s)) was 21 and 45 h for Cr(III) and Cr(VI), respectively, and a breakthrough time (t(b)) of 4 h for Cr(III) and 5 h for Cr(VI). The uptake capacity of the biosorbent for Cr(III) and Cr(VI) were 48 and 60 mg/g, respectively. Two non-diffusional mathematical models with parameters to and a were used to adjust the experimental data obtained. Microsoft Excel tools were used for the mathematical solution of the two parameters used. (C) 2007 Published by Elsevier B.V.