Ozonated and autoclaved piggery wastewaters were compared for cultivation of oil-rich Chlorella pyrenoidosa by measuring nutrient removal from the medium and growth rate and lipid production of the microalgae. The removal rates of chemical oxygen demand, NH4+-N, total nitrogen and total phosphorus by C. pyrenoidosa were not influenced by both sterilisation methods. The specific growth rate and biomass of C. pyrenoidosa were determined by analysing the chlorophyll concentration for eliminating the disturbance of bacteria growth in culture system. Bacteria raised from the residue in the ozonated medium achieved 30% of the total microorganisms at the end of cultivation. They reduced the growth of C. pyrenoidosa by 10.4%, but contributed to a faster decline of the nutrient content on the first day. Lipid production and fatty acid profile did not change markedly in both sterilisation methods. The results suggest that ozonation is acceptable for piggery wastewater treatment for C. pyrenoidosa cultivation. (C) 2014 Elsevier Ltd. All rights reserved.