The potential use of Mowital(R)B30H resin immobilized dried activated sludge as a substitute for granular activated carbon for removing chromium(VI) was examined in a continuous packed bed column. The effect of operating parameters such as flow rate and inlet metal ion concentration on the sorption characteristics of each sorbent was investigated. From the batch system studies the working sorption pH value was determined as 1.0 for both sorbents and packed bed sorption studies were performed at this pH value. The total adsorbed quantities, equilibrium uptakes and total removal percents of chromium(VI) related to the effluent volumes were determined by evaluating the breakthrough curves obtained at different flow rates and different inlet chromium(VI) concentrations for each sorbent. Data confirmed that the total amount of sorbed chromium(VI) and equilibrium chromium(VI) uptake decreased with increasing flow rate and increased with increasing inlet chromium(VI) concentration for both immobilized dried activated sludge and granular activated carbon systems. The results also indicated that the sorption process could only deal with lower flow rates and lower concentrations of chromium(VI) solutions if a high percentage removal was required for extended periods for both sorbents. The suitability of the Freundlich and Langmuir adsorption models to the column equilibrium data was also investigated for each chromium(VI)-sorbent system. The results showed that the equilibrium data for both the sorbents fitted the Langmuir model best within the concentration range studied. (C) 2002 Elsevier Science Ltd. All rights reserved.