The present investigation examines the way to enhance aerobic granulation by controlling the microbial communities via applying different settling times. Early granulation of aerobic granules is noticeable at a settling time of 5 min. The functional strains are enriched in granules without challenge of non-flocculating strains. Short settling times at initial stage principally determine the efficiency of subsequent granulation processes. (C) 2009 Elsevier Ltd. All rights reserved.