| 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 searchfor renewable energy. Renewable energy, including Solar Energy, Wind Energy andBioenergy, China is a traditional agricultural country, has a huge potential advantage in thedevelopment of biomass energy. An important way to get biomass energy is to makebiodiesel by esterification through extract oil from microalgae. Microalgae, as a promisingsource for bioenergy, have been investigated for many years due to its short growth cycleand high lipid content.Our previous studies have shown that ultra-low-acid hydrolysis of straw hydrolyzatecan be used for high-density culture of Chlorella pyrenoidosa. Adding carbon source intomedium can raise the cell density level. However, the raw hydrolyzate usually containssome toxic substances such as furfural and HMF that might inhibit microbial growth. Onthe other hand, furfural and HMF have high economic value. In this thesis, nanofiltration(NF) and reverse osmosis (RO) technology were used to detoxify the straw hydrolyzate,mainly inspected furfural and5-(hydroxymethyl) furfural (HMF) removal effect.During the cultural of microalgae, there is contamination between the microalgae andother bacteria, So far, the hydrolyzate has been considered as an additional carbon sourceby many researchers. Non-symbiotic bacteria are harmful for the algae growth and somealgicidal bacteria are even fatal for the microalgae. Bacteriostatics having a good inhibitoryeffect against bacteria, in this study, the effects of Rose Bengal, Nystatin and StreptomycinSulphate on the growth of Chlorella pyrenoidosa were investigated.The main findings are as follows:1. An effective and rapid method for determination of Xylose, Glucose, Furfural andHMF in hydrolyzate using UV-Vis Spectroscopy was established. Good linear correlationfor these four substances were in the concentration range of0-2mmol·L-1for Xylose andGlucose,0-0.2mmol·L-1for Furfural and HMF, respectively. The recoveries of Xylose, Glucose, Furfural and HMF were96.67%-102.85%,94.79%-105.71%,95.24%-102.04%and99.75%-105%, respectively.2. The effect of pressure, temperature. pH and feed concentration on the membraneseparation performance of lignocellulosic hydrolyzate were also investigated. Undercertain experimental conditions, NF membranes may reach80%to91.14%rejection ofxylose, more than90%rejection of glucose,-5%to2%rejection of HMF and-3%to1%rejection of furfural, respectively; RO membrane rejection of xylose and glucose weremore than97%and99%, respectively;60%to70%rejection of furfural and70%to80%rejection of HMF.3. The algae was cultivated under25°C and illuminated12hours a day at intensitiesof4000lux in BG-11Medium, Rose Bengal and Streptomycin Sulphate had a positiveeffect on stimulating the growth of Chlorella pyrenoidosa, where the maximum of algaedensity were4.216×107cell·mL-1and3.512×107cell·mL-1, respectively. Those celldensities are higher than the group without any antibiotic whose density was3.325×107cell·mL-1. Nystatin, as well as the mixtures of Rose Bengal and Streptomycin Sulphateshowed negative effects on microalgae growth.4. Rose Bengal and Streptomycin Sulphate had almost no effect on lipid content. ForSupercritical CO2extraction and Soxhlet extraction, the lipid content of Rose Bengaltreatment groups decreased by0.5%for control group, a decrease of2.12percent and2.18percent; streptomycin sulfate the lipid content of Rose Bengal treatment groups decreasedby0.1%and0.8%for control group, a decrease of0.42percent and3.49percent,respectively. |
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