| Due to the depletion of fossil fuels and the severe global climate problems,governments and research institutions all over the world are making great effort to search for renewable energy.Microalgae, as a potential source for bioenergy, has been investigated for many years due to its short growth cycle and high lipid content. Adding carbon source and nitrogen source into culture medium can raise the cell density level, realizing the high density culture of microalgae.In this study, the main findings are as follows:?1? The heterotrophic growth of Chlorella pyrenoidosa in simulated microgravity and general environment with glucose or nitrogen culture mediumwere studied.The results showed that the algal cell density of 1.58×108-1× mlcell could be obtained in simulated microgravity.The algal cell density of 0.58 ×108-1× mlcell could be obtained in general environment.In the two different environment's the culture medium with glucose of 10-1× Lg was most suitable for the growth of Chlorella pyrenoidosa. Glucose was a good carbon source for promoting the growth and heterotrophic growth was suitable for mass culture. The algal cell growth cycle could be significantly shortened in the culture medium with glucose and algal cell density of 3 days of cultivation could as high as that of 12 days in the culture medium without glucose. The algal cell density of 4.85 × 108-1× mlcell could be obtained in general environment.Microalgae in simulated microgravity environment for 3 days could reach a concentration that required 5 days of culture in normal environment.The algal cell density of 5.42 ×108-1× mlcell could be obtained in simulated microgravity.?2?The heterotrophic growth of Chlorella pyrenoidosa in two different environment with urea culture medium were studied. Experimental results showed that in the two different environment's the culture medium with nitrogen of 0.0025-1× Lmol was most suitable for the growth of Chlorella pyrenoidosa.When urea was added into the culture medium, Chlorella pyrenoidosa grew faster in the microgravity environment. When the urea concentration is 0.0025-1× Lmol, the algal cell density of 8.93 ×107-1× mlcellcould be obtained in simulated microgravity.The algal cell density of 6.50 ×107-1× mlcell could be obtained in general environment.?3?The two different environment's Chlorella pyrenoidosa to phenol poisoning with the resistance of Chlorella pyrenoidosa to phenol were studied. The results showed that when the concentration of phenol was1200-×?27? Lmg,it could stimulate Chlorella pyrenoidosa growth. Low concentration of phenol can be used as additional carbon source,promoting the growth of Chlorella pyrenoidosa.Micro algae in ordinary environment1300-×?29? Lmg concentration of phenol could inhibit the growth of Chlorella pyrenoidosa.And largest phenolic lethal dose is 600-1× Lmg.When the concentration of phenol was high, it could inhibit the growth of Chlorella pyrenoidosa.The resistance of Chlorella pyrenoidosa to phenol poisoning was improved significantly after domestication treatment.Microalgae in ordinary circumstances after domestication is biggest phenol a lethal dose of800-1× Lmg.Chlorella pyrenoidosa domesticated after simulated microgravity environment Chlorella pyrenoidosa. phenol lethal concentration is 1000-1× Lmg.?4? Biodiesel was prepared via in-situ transesterification method, with methanol as solvent, chlorella pyrenoidosa algae as precursor and sulfuric acid as catalyst. The effects of different process conditions on the biodiesel yield were investigated. The optimal conditions for the reaction were: mass ratio of water to algae powder 1:1, mass fraction of catalyst?H2SO4? 3%, reaction temperature 65 ?, mass ratio of methanol to algae powder8:1, and reaction time 8 h. The results showed that the conversion rate of algae powder to crude microalgae biodiesel was 16.0%, the content of biodiesel in crude microalgae biodiesel was 43.5% as determined by HPLC analysis and the conversion rate of algae powder to microalgae biodiesel was 6.96%. |
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