A three-step sequencing batch reactor (SBR) was used for nutrient removal from synthetic wastewater with different glucose-organic acid mixtures (1/1). Acetic. butyric. propionic and citric acids were used as organic acids along with glucose. The operation consisted of anaerobic. anoxic and oxic (An/Ax/Ox) phases with durations of 2/l/4.5 h. Sludge age was kept constant for 10 days. Phosphate release Pr and uptake rates were determined for different glucose-organic acid mixtures in the feed wastewater. Maximum phosphate uptake (8.1 mg PI-1 h(-1)) and release rates (2.23 Ing PI-1 h(-1)) were obtained with the glucose-citric acid mixture. The highest (96%) percent phosphate removal at the end of the nutrient removal cycle (7.5 h) was also obtained with the glucose-citric acid mixture while the glucose-acetic acid mixture resulted in comparable percent phosphate removal (95%). (c) 2005 Elsevier Ltd. All rights reserved.