Microalgae have high potential to remove inorganic nutrients from wastewater and to produce biodiesel. Effects of nitrogen and phosphorus concentrations on growth, nutrient uptake, and lipid accumulation of a freshwater microalga Scenedesmus sp. LX1 were studied. Scenedesmus sp. LX1's growth was in accordance with the Monod model. The following Monod parameters were obtained: the N- and P-saturated maximum growth rate was 2.21 x 10(6) cells mL(-1) d(-1), and the half-saturation constants of N and P uptake were 12.1 mg L(-1) and 0.27 mg L(-1), respectively. In the nitrogen/phosphorus ratio of 5:1-12:1, 83-99% nitrogen and 99% phosphorus could be removed. In conditions of nitrogen (2.5 mg L(-1)) or phosphorus (0.1 mg L(-1)) limitation, Scenedesmus sp. LX1 could accumulate lipids to as high as 30% and 53%, respectively, of its algal biomass. The lipid productivity/unit volume of culture, however, was not enhanced. Further research should be made on how to enhance both lipid content and lipid productivity. (C) 2010 Elsevier Ltd. All rights reserved.