Oleaginous microalgae Chlorella vulgaris has been identified as potential algal species for biodiesel production. The information on behaviour of this algae under abiotic (pH, ambient temperature and photoperiod) and nutrient stress is limited. This study aimed to investigate the effect of pH (2, 5, 7, 9 and 11), temperature (10, 20, 30 and 40 degrees C), photoperiod (continuous light, 24:0 h; light and dark, 18:6 h; and continuous dark, 24:0 h) and nutrient load (N-NO3- and PO4-3) on growth and chemical composition of harvested biomass of Chlorella. Result indicates the optimum ranges of abiotic conditions as 18:6 h light/dark regimes (photoperiod), 7-9 pH and 20-30 degrees C temperature for algal cultivations. After optimizing the abiotic culture conditions, the second experiment (the role of nutrient load on algal biomass yield) was conducted. Results suggested the maximum biomass (thy-weight basis) production 0.439 g/L at 50 mg/L N-NO3- and 0.34 g/L at 25 mg/L PO4-3 loads in media. The maximum biomass yield was 159 mg L-1 day(-1) and 114 L-1 day(-1) with optimum loads of N-NO3- and PO4-3, respectively at the end. The chlorophyll (a and b) and, sugar contents in algal biomass showed the direct relationships with nutrient loads in the culture media. Results suggest that growth and chemical quality of C. vulgaris biomass can be scaled by optimizing the abiotic and nutrient loads in algal reactors. (C) 2017 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.