Effects Of Environmental Factors On Biological Desalination And Lipid Production Mechanism By Microalgea Scenedesmus Obliquus

The arid region of Northwest China is one of the harshest arid regions in the world.Additionally,most of the water resources in this area exist in an unusable form,such as salt water.Therefore,it is important to make efficient use of salt water for the improvement of the environment and mitigate drought of Northwest China.The purposes of this study were to reduce the Na⁺and Cl^-concentrations in the salt water by using Scenedesmus obliquus which can absorb and adsorb salt effectively,and to produce biodiesel by S.obliquus.It can effectively compensate for the consumption of water resources in the arid areas of Northwest China.The study of the effect of environmental factors on water desalination and lipid production of S.obliquus instructs to make further optimization of the S.obliquus application,such as increase efficiency and reduce costs.The main results of this study are as follows:?1?The desalination of S.obliquus in high-concentration brine was better,but the lipid production was inversely proportional to the salt concentration.Taking into account the desalination and lipid production of S.obliquus,the optimum salt concentration was 4.8 g L^-1NaCl.The desalting mechanism of S.obliquus was studied.It was found that the desalination effect of S.obliquus was 67%from adsorption and 33%from absorption.Combined with results of electron microscopy and infrared spectroscopy,we could find that NaCl binds to algal cells in the crystalline form and proteins and fatty acids worked together to achieve desalination.?2?The desalination effect of S.obliquus appeared to increase first and then decrease with the increase of light intensity and temperature,while the lipid production increased continuously with the increase of light intensity.The optimal light and temperature conditions were 50?mol photons m^-2s^-1 and 25 ^oC,respectivly.?3?The lipid content of S.obliquus is positively related to initial N concentration,and that increasing initial P concentration clearly enhanced the proportion of C16-C18 fatty acid and the unsaturation level.The above study found that the optimum nutrient regime was 46mg L^-1 N and 5.44 mg L^-1 P.