Study On The Intensified Microalgae Culture And Lipid Production

Being the important stuff of biodiesel, lipids are usually deprived from animals or plants, but the low lipid productivity has been one of the major obstacles impeding commercial biodiesel production. Compared with higher animals and plants, microalgae can grow faster and accumulate more lipids, and thus is regarded as the most potential "factory" for lipid production. In our work, intensifying of microalgae culture and lipid production was investigated, aiming at increasing the lipid productivity and reducing the production cost.To increase the lipid productivity, effects of cultivation conditions including KNO3-level, KH2PO4 concentration, salinity, CO2 concentration, light intensity and temperature on the cell growth, chlorophyll a content and lipid accumulation of Chlorella vulgaris were systematically investigated in the bubble column. The results included:1) during the batch culture of Chlorella vulgaris, the lipid productivity was the largest when cells were harvested at the early stationary phase; 2) effects of culture conditions on the cells growth were not consistent with that on the lipid accumulation, and when conditions were controlled at 1.0 mM KNO3,10 mg L"1 KH2PO4,50 g L-1 salinity,1.0% CO2,60μmol photons m-2 s-1 and 38℃, the highest lipid productivity was obtained.To reduce the production cost, effects of light intensity and temperature on the growth of Chlorella vulgaris, as well as influences of application of the recycled broth and semi-continuous culture mode, were discussed in the indoor raceway pond. The results showed:1) the growth of Chlorella vulgaris was accelerated under 120μmol m-2 s-1 at 25℃; 2) the growth and lipid accumulation of Chlorella vulgaris grown in the recycled broth remained similar with that in the fresh broth, and when the semi-continuous mode was adopted in stead of the batch, the lipid productivity was doubled in either the fresh broth or the recycled.