Excess nutrients, particularly nitrogen and phosphorus remaining in anaerobically digested liquid manure (AD) effluent, have major impacts on the environment if disposed of inappropriately. Algal cultivation, with the advantage of a faster uptake of nutrients in effluent streams, represents one of the best processes for the removal of excessive nutrients. Meanwhile, algae have also been proved as one of the most promising non-food-crop-based feedstock for biofuels production. This study applying ecological approach on an open algal cultivation system elucidated that non-filamentous green algae, especially Chlorella, were able to tolerate high nutrient loadings in a five-month cultivation; a chemically pretreated AD effluent which contained 200 g m (3) of total nitrogen and 2.5 g m (3) of total dissolved phosphorus (TDP) provided an optimal nutrient concentration for the cultivation of selected algae. Additionally, the cultivation of selected algae with optimal pretreated AD effluent in a pilot-scale semi-continuously fed raceway pond revealed a stable algal biomass productivity of 6.83 g m (2) d(-1). (C) 2011 Elsevier Ltd. All rights reserved.