Four common used microalgae species were compared in terms of settleability, nutrient removal capacity and biomass productivity. After 1 month training, except cyanobacteria Phormidium sp., three green microalgae species. Chlamydomonas reinhardtii, Chlorella vulgaris and Scenedesmus rubescens, showed good settleability. The N and P removal efficiency was all above 99% within 7, 4, 6 and 6 days for N and 4, 2, 3 and 4 days for P. resulting in the N removal rates of 3.66 +/- 0.17, 6.39 +/- 0.20, 4.39 +/- 0.06 and 4.31 +/- 0.18 mg N/l/d and P removal rates of 0.56 +/- 0.07, 0.89 +/- 0.05, 0.76 +/- 0.09 and 0.60 +/- 0.05 mg P/l/d for Phormidium sp., C. reinhardtii, C. vulgaris and S. rubescens, respectively. Phormidium sp. had the lowest algal biomass productivity (2.71 +/- 0.7 g/m(2)/d) and the other three green microalgae showed higher algal biomass productivity (around 6 g/m(2)/d). Assimilation into biomass was the main removal mechanism for N and P. (C) 2012 Elsevier Ltd. All rights reserved.