Effect Of Different Nutritional Conditions And Culture Methods On The Growth And Lipid Content Of Chlorella Vulgaris

As the similar physical and chemical properties, biodiesel is considered as the most potential bio-energy to solve the energy crisis in future. As for the important stuff for preparation of biodiesel, lipids are usually obtained from animals or plants, but the low lipid productivity prohibits the commercial production of biodiesel. Compared with higher animals and plants, microalgae grow faster, have the relative high lipid content and can provide the enough lipid productivity. In this work, effects of culture conditions on the growth and lipid content of Chlorella vulgaris as well as optimization of batch cultivation were investigated in the Erlenmeyer flask.To increase the lipid productivity, effects of different cultivation styles such as autotrophy and heterotrophy and different conditions including nitrate, KH2PO4 concentration, on the cell growth, chlorophyll a content and lipid accumulation of freshwater Chlorella vulgaris were systematically investigated. The biochemical compositions including carbohydrates, proteins and lipids were analyzed simultaneously by a novel FT-IR spectroscopy. 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 low nitrate, the highest lipid percentage obtained beyond 20%; 3) the lipid accumulation could be influenced by Mg2+ and Ca2+ concentration.In the text, the combination of PBD screening and RSM analysis is applied on the optimization of lipids production process by Chlorella vulgaris. And the research shows that PBD could be used to successfully screen the key factors from plenty of nutritional conditions promptly and efficiently which play an important role on the biomass and lipid content of Chlorella vulgaris.Besides, effects of combination of secondary wastewater and BG11 medium on the growth and lipid percentage of Chlorella vulgaris have been investigated, including combined ratio as well as influences of application of disinfection. The results showed:1) the relative composition ratio is influenced significantly by the wastewater mixed. Rather than cell component cultivated in autotrophy, protein is accumulated in heterotrophy mostly; 2) the difference of biomass of Chlorella vulgaris under the mixed medium is very obvious. While the ratio of volume of wastewater and BG11 is 1:1, the most biomass is obtained at almost 1000 mg·L-1.