Large amount of waste produced in the livestock industry could be reused to produce valuable products such as microalgae, which are used predominantly in the primary treatment of wastewater for bioremediation. In this study digested piggery effluent was used as nutrient source to substitute mineral nutrients for culturing feed grade Chlorella vulgaris. Two experiments were conducted to investigate the effect of total ammonia nitrogen (TAN) levels, inoculum mediums and the feeding frequencies on the performance of C. vulgaris. The first experimental results showed that 20 mg TAN/l in the culture media resulted in better algal SGR (0.345/day; P > 0.05). The adding 200 ml effluent into 101 culture medium at the start (20.6 mg TAN/l) in the second experiment resulted in a large increase of algal population from day 1 to 6 and reached 11.9 million algae/ml at day 6. This study indicated that high production of C. vulgaris could be achieved at short time by feeding digested effluent once. Crown Copyright (C) 2010 Published by Elsevier Ltd. All rights reserved.