Investigation of effective parameters on biomass and lipid productivity of Chlorella vulgaris

Abstract

Background and purpose: In recent years, microalgae lipid has attracted considerable attention for biodiesel production due to its carbon-neutral status and Chlorella vulgaris is one of the most interesting candidates. Materials and methods: In the present study, initially, the effects of temperature and inorganic carbon source on C. vulgaris microalgae were investigated in terms of biomass concentration, lipid content and productivity. Afterwards, one of the statistical experimental designs, response surface methodology was applied to find the optimum amount of light intensity and photoperiod that highly influence on microalgae growth and lipid content. Results and conclusions: Results showed that C. vulgaris could grow in a wide range of temperature (25 ° ­C-­35­ ° C). The optimal temperature to produce maximum microalgae biomass and lipid was 30­ ° C and the biomass production of 394 mg/l and lipid productivity of 6.07 mg/l.d were obtained after 7 days of batch cultivation. Using a higher concentration of sodium carbonate, tenfold of control experiment, along with 0.03% carbon dioxide from the aeration could substantially enhance the microalgae growth rate (0.66 d -1 ), biomass production (500 mg/l) and lipid productivity (7.34 mg/l.d). According to the results of experimental design, illumination of 3500 lux and photoperiod of 12:12 hour were the optimum amounts that led to a twofold increase in biomass and lipid productivity compared with unoptimized condition.