Study On Growth And Carbon Sequestration Performance Of Scenedesmus Obliquus Based On Sewage Treatment

Under the background of water resources crisis and the depletion of fossil energy,water pollution and resource shortage are the survival challenges faced by our country and even the whole world.Compared with traditional bioenergy,microalgae has become a highly potential raw material for bioenergy due to its rapid growth capacity and high energy conversion rate,which has aroused widespread concern around the world.Nutrients and water sources have become one of the main factors restricting the industrial production of microalgae.Taking advantage of the characteristics of some microalgae,it is possible to use exogenous organic carbon for mixed growth.Microalgae cultivation can be combined with sewage treatment.Microalgae can absorb and utilize the organic carbon and nitrogen and phosphorus pollutants in the sewage while accumulating biomass and lipid,and reducing the production cost of biodiesel,have a positive significance for the environment and economy.In this paper,glucose was used as the source of organic carbon,the effect of glucose concentration on the growth of Scenedesmus obliquus and the utilization of organic carbon under different light conditions were explored.The optimal organic carbon concentration wss determined;on this basis,several kinds typical carbon sources in nature were investigated for their effects on the growth characteristics of Scenedesmus obliquus under different light conditions,in order to provide a basis for the treatment of different types of sewage by Scenedesmus obliquus.Finally,the actual secondary treatment effluent was used as the medium,by setting different environments conditions were investigated,and the growth and the removal effect of pollutants were investigated.And the experiment was verified by co-cultivating Scenedesmus obliquus under optimized conditions.The following conclusions were obtained:（1）The addition of glucose had a promoting effect on the growth of Scenedesmus obliquus and lipid accumulation,but it was not good for chlorophyll synthesis.The optimal concentration was 100mg L^-1.Under normal light,the dry weight of algae harvested was 1.05g L^-1,and the lipid content was28.17%.Under low light,growth was inhibited,Chlorophyll and lipid content have been reduced,but glucose utilization efficiency at 100 mg L^-1was higher,87.8%（2）With the addition of different organic carbon sources,the growth of Scenedesmus obliquus was better than that of the blank group.Cell proliferation and lipid accumulation were promoted,and chlorophyll synthesis was inhibited.The utilization rate of carbon source did not correspond to the growth of microalgae under the corresponding carbon source,and the promotion effect was different under different light sources,indicating that the type of carbon source and the light intensity had an interactive effect on the growth of microalgae.Overall,the adaptability to organic acid salts and monosaccharides was the best,followed by alcohols,and the polysaccharides were the worst.Comprehensive analysis of the experimental results showed that Scenedesmus obliquus had the highest utilization efficiency of sodium acetate and the most obvious growth promotion effect,which was the best carbon source for this experiment.（3）According to the actual growth status of the Scenedesmus obliquus and the pollutant removal rate in the secondary effluent,it could be seen that the removal efficiency of pollutants under unsterilized conditions was higher,and it did not significantly inhibit the growth of Scenedesmus obliquus function;Scenedesmus obliquus domesticated by organic carbon had better adaptability to actual sewage,showed stronger vitality,could quickly remove pollutants,and achieved a higher removal rate.20%of algae species was the best.The growth condition was good.The algae density was too large but it could cause photo-suppression phenomenon.When adding 20%algae species,the maximum lipid content was 16.7%and the maximum COD removal rate was 90.3%。（4）Operating under the optimized experimental conditions in the early stage,the removal rates of TN,TP and COD have all been improved.The removal rate of COD was 94.5%,the removal rate of TN was 97.6%,the concentration of TP was lower than the detection limit,the removal rate reaches 98 More than%,the dry weight of the harvested organism was 0.45g L^-1,and the oil content was 21.4%.