Iron precipitate was produced with 0.1 M FeCl3 and bound with the amino or hydroxyl groups of the granules surface, accompanied with removal of Ca, Mg, K and Na from the biomass matrix. The Fe(III)-treated granules exhibited much higher adsorption capacity of antimony(V) than the untreated granules, peaked at pH 3.4 at a maximum capacity of 22.6 mg g(-1) of dry mass. The intraparticle diffusion and film diffusion resistances controlled the Sb(V) adsorption onto the Fe(III)-treated granules. Fe(III) treatment is a cost-effective and easy-to-implement process to modify the surface of aerobic granules to enhance their adsorption capacity to Sb(V). (C) 2014 Elsevier Ltd. All rights reserved.