Study On Culture Conditions Of Lipid Accumulation For Biodiesel Production With Chlorella Vulgaris

Microalgae have been regarded as one of the most promising feedstocks for biodieselproduction owing to their fast growth, short cultivation period, high biomass and lipidproductivity. But high cost is still the main restriction for commercial biodiesel production.So it is significant to study how to reduce cost of microalgal lipids production. How topromote growth and lipid accumulation of Chlorella vulgaris (FACHB1068) and decreaseculture cost at the same time were studied and the results were as follows:(1) Mixotrophic cultivation was the optimal culture mode for C. vulgaris growth andlipid accumulation. In mixotrophic cultivation, C. vulgaris grew fast after short adaptivephase and entered into stationary phase in the third day. Comparing biomass and lipidproductivity in three different trophic modes, greatest biomass and lipid productivity wereobtained in mixotrophic cultivation.(2) Lipid accumulation was closely related with biomass productivity, so improvingbiomass productivity would lead to high lipid productivity. After extraction, lipids wereused to produce FAMEs (Fatty Acid Methyl Esters) by transesterification. The cetanenumber and iodine value of FAMEs were57.88and89.97, which met the standards ofAmerica and European Union. It meant that lipids produced from C. vulgaris could beused for biodiesel production.(3) Sodium acetate had great influence on C. vulgaris growth and lipids accumulation.Sodium acetate was helpful to promote lipid accumulation, but representativemonounsaturated fatty acids (oleic acid) content decreased significantly, which wouldaffect biodiesel quality. The maximum lipid productivity was about0.44g/L, the same ascultured in glucose medium, because sodium acetate was not favor for obtaining highbiomass productivity. Considering lipids properties, glucose was more suitable thansodium acetate as carbon source for cultivating C. vulgaris in mixotrophic cultivation.(4) It greatly decreased the medium cost when potato starch wastewater hydrolysatewas used as medium. Potato starch wastewater hydrolysate alone could replace themedium with higher biomass productivity, similar lipid yield and lipid profiles comparedwith glucose-based medium, which reduced the medium cost significantly. The cost of lipid production from C. vulgaris was greatly reduced with above study,which laid the foundation to reduce the total cost of biodiesel production.