This study discusses the retention of Ni(II) by Arthrobacter viscosus supported on zeolite 13 X in batch mode and in continuous mode, at laboratory scale and at pilot scale. The maximum adsorption capacities of 28.37, 20.21 and 11.13 mg/g were recorded for lab scale batch, for continuous lab scale minicolumns and for pilot scale bioreactors, respectively. The Sips isotherm and pseudo second order kinetics described well the observations registered in batch assays. The Adams-Bohart, Thomas and Yoon-Nelson models were applied to data obtained with the pilot scale bioreactor and a good fit was reached for Adams-Bohart and for Yoon-Nelson models. A fed-batch was performed at lab scale and the applicability of the biofilm in continuous mode for the described purpose was confirmed. The sorption mechanism was investigated in detail through FTIR, SEM and EDX analyses. (C) 2013 Elsevier Ltd. All rights reserved.