(1) State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, Hubei 430072, China; (2) Graduate University of the Chinese Academy of Sciences, Beijing 100049, China; (3) School of Biological Engineering, Hubei University of Technology, Wuhan, Hubei 430068, China; (4) Algaen Corporation, 925 West Northwest Boulevard, Winston Salem, NC 27101, United States
Culturing microalgae using natural sunlight is an effective way to reduce the cost of microalgae-based biodiesel production. In order to evaluate the feasibility of culturing Chlorella zofingiensis outdoors for biodiesel production, effects of nitrogen limitation and initial cell concentration on growth and lipid accumulation of this alga were investigated in 60L flat plate photobioreactors outdoors. The highest μmax and biomass productivity obtained was 0.994day-1 and 58.4mgL-1day-1, respectively. The lipid content was much higher (54.5% of dry weight) under nitrogen limiting condition than under nitrogen sufficient condition (27.3%). With the increasing initial cell concentrations, the lipid contents declined, while lipid concentrations and productivities increased. The highest lipid content, lipid concentration, and lipid productivity obtained was 54.5%, 536mgL-1 and 22.3mgL-1day-1, respectively. This study demonstrated that it was possible to culture C. zofingiensis under outdoor conditions for producing biodiesel feedstock.