气升式光生物反应器中Chlorella sp.优化培养与油脂提取
发布时间：2018-12-13 15:40
【摘要】：富油微藻能够有效地利用太阳能生产生物柴油,从而实现从无机碳到有机碳的绿色转化。然而,在提高油脂产量的同时降低微藻培养过程的能耗,是实现微藻生物柴油商业规模化生产的关键。本文选择能够耐受较高浓度CO2的Chlorella sp.作为模型生物,探讨了在气升式光生物反应器中微藻培养条件的优化及能量利用效率提高的问题,并对下游脂质提取技术和脂肪酸分析进行初步研究。与以往许多相关研究不同,本文从能量利用而不仅是生物产量的角度来考察整个培养过程,希望为以微藻为原料的生物柴油生产提供有价值的借鉴。通过对比不同CO2浓度和光照条件下Chlorella sp.生长情况,发现CO2浓度提高和光照强度的增大都能显著促进其生长速率的提高。同时光源会影响碳源的利用,因光照强度的差异,外置光源和内置光源的最适二氧化碳浓度分别为10%(v/v)和5%(v/v),最大生物量浓度分别为3.68 g/L,0.47 g/L。当保持CO2浓度为5%时,Chlorella sp.在光强为15.6 W/m2时获得最大生物量浓度和最大生物产量,分别为3.63g/L和246.35 mg/(L·d)。由于光照较弱,内置光纤的净产量仅为28.30 mg/(L·d),然而与外置光源相比侧光光纤能够将光更有效地分散于培养基中,其光能利用率大大提高。消耗相同能量时,内置光源系统的生物产量较外置光源提高了8.6～25.6倍,在适宜的通气速率下(0.6 L/min),单位能耗生物产量最高可达4.40g/(W·d)。氮饥饿能促进脂质积累但不利于生物产量的提高,缺乏氮源时Chlorella sp.可能利用叶绿素等作为胞内氮源,随着氮饥饿的延长叶绿素a浓度降低。当培养基中NaNO3和柠檬酸铁铵浓度分别为1.5 g/L和6 mg/L时,脂质产量可达到最大值5.66 mg/(L·d)。 Chlorella sp也能够在有机物和光源同时存在时进行混合代谢,在模拟生活污水中比生长率及油脂产量分别达到0.0033d-1和6.96 mg/(Ld),污染物去除率达到95%以上。研磨、超声、反复冻融和酸热均能达到不同程度的细胞破壁效果,其中超声处理的破壁率最高达到65.25%。四种有机溶剂中,乙醇溶剂的提取效果最优,在60。C时获得22.00%的最大油脂得率。Chlorella sp.的脂肪酸中C16和C18占主要优势,多元不饱和脂肪酸酸含量相对较少,能够满足一些商用生物柴油的标准。另外,不同提取溶剂和培养条件均会对脂肪酸组成和含量产生影响。因此,我们可以根据需求定向地选择有机溶剂和培养条件来优化生物柴油产品的品质。
[Abstract]:Oil rich microalgae can effectively use solar energy to produce biodiesel, thus realizing the green conversion from inorganic carbon to organic carbon. However, the key to commercial production of microalgae biodiesel is to increase oil production and reduce energy consumption in microalgae culture process. In this paper, we select Chlorella sp. which can tolerate higher concentration of CO2. As a model organism, the optimization of microalgae culture conditions and the improvement of energy use efficiency in an air-lift photobioreactor were discussed, and the downstream lipid extraction techniques and fatty acid analysis were preliminarily studied. Different from many previous studies, the whole culture process was investigated from the point of energy utilization, not just biological yield, in order to provide valuable reference for biodiesel production using microalgae as raw material. Chlorella sp. was compared under different CO2 concentrations and illumination conditions. It was found that the increase of CO2 concentration and light intensity could significantly increase the growth rate. At the same time, the light source will affect the use of carbon source. Because of the difference of light intensity, the optimum carbon dioxide concentration of external light source and built-in light source is 10% (v / v) and 5% (v / v), respectively, and the maximum biomass concentration is 3.68 g / L, respectively. 0.47 g/L. , Chlorella sp. when the concentration of CO2 is kept at 5 Maximum biomass concentration and maximum biomass yield were obtained at a light intensity of 15.6 W/m2, 3.63g/L and 246.35 mg/ (L d)., respectively. The net output of built-in optical fiber is only 28.30 mg/ (L d), due to weak illumination. Compared with external light source, side-light fiber can disperse light more effectively in medium, and its light energy utilization rate is greatly improved. When the energy consumption is the same, the biological output of the built-in light source system is increased by 8.6U 25.6 times than that of the external light source. At the appropriate ventilation rate (0.6 L/min), the biological output per unit energy consumption can reach the maximum 4.40g/ (W d). Nitrogen starvation can promote lipid accumulation, but it is not conducive to the increase of biological yield. Chlorella sp. is lack of nitrogen source. Chlorophyll was probably used as a source of intracellular nitrogen, and the concentration of chlorophyll a decreased with the prolongation of nitrogen starvation. When the concentration of NaNO3 and ammonium ferric citrate were 1.5 g / L and 6 mg/L, respectively, the lipid production reached the maximum value of 5.66 mg/ (L d). Chlorella sp can also be mixed metabolized when organic matter and light source exist at the same time. In simulated domestic sewage, the specific growth rate and oil yield can reach 0.0033d-1 and 6.96 mg/ (Ld), pollutant removal rate of more than 95% respectively. Grinding, ultrasonic, repeated freezing and thawing and acid heat can achieve different degrees of cell wall breaking effect, among which ultrasonic treatment can achieve the highest broken wall rate of 65.25%. Of the four organic solvents, ethanol was the most effective solvent, and the maximum oil yield of 22.00%. Chlorella sp. was obtained at 60.C. C16 and C18 are the main fatty acids, and the polyunsaturated fatty acid content is relatively low, which can meet the standard of some commercial biodiesel. In addition, the composition and content of fatty acids were affected by different extraction solvents and culture conditions. Therefore, we can select organic solvents and culture conditions to optimize the quality of biodiesel products.
【学位授予单位】：大连理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TE667
本文编号：2376783
[Abstract]:Oil rich microalgae can effectively use solar energy to produce biodiesel, thus realizing the green conversion from inorganic carbon to organic carbon. However, the key to commercial production of microalgae biodiesel is to increase oil production and reduce energy consumption in microalgae culture process. In this paper, we select Chlorella sp. which can tolerate higher concentration of CO2. As a model organism, the optimization of microalgae culture conditions and the improvement of energy use efficiency in an air-lift photobioreactor were discussed, and the downstream lipid extraction techniques and fatty acid analysis were preliminarily studied. Different from many previous studies, the whole culture process was investigated from the point of energy utilization, not just biological yield, in order to provide valuable reference for biodiesel production using microalgae as raw material. Chlorella sp. was compared under different CO2 concentrations and illumination conditions. It was found that the increase of CO2 concentration and light intensity could significantly increase the growth rate. At the same time, the light source will affect the use of carbon source. Because of the difference of light intensity, the optimum carbon dioxide concentration of external light source and built-in light source is 10% (v / v) and 5% (v / v), respectively, and the maximum biomass concentration is 3.68 g / L, respectively. 0.47 g/L. , Chlorella sp. when the concentration of CO2 is kept at 5 Maximum biomass concentration and maximum biomass yield were obtained at a light intensity of 15.6 W/m2, 3.63g/L and 246.35 mg/ (L d)., respectively. The net output of built-in optical fiber is only 28.30 mg/ (L d), due to weak illumination. Compared with external light source, side-light fiber can disperse light more effectively in medium, and its light energy utilization rate is greatly improved. When the energy consumption is the same, the biological output of the built-in light source system is increased by 8.6U 25.6 times than that of the external light source. At the appropriate ventilation rate (0.6 L/min), the biological output per unit energy consumption can reach the maximum 4.40g/ (W d). Nitrogen starvation can promote lipid accumulation, but it is not conducive to the increase of biological yield. Chlorella sp. is lack of nitrogen source. Chlorophyll was probably used as a source of intracellular nitrogen, and the concentration of chlorophyll a decreased with the prolongation of nitrogen starvation. When the concentration of NaNO3 and ammonium ferric citrate were 1.5 g / L and 6 mg/L, respectively, the lipid production reached the maximum value of 5.66 mg/ (L d). Chlorella sp can also be mixed metabolized when organic matter and light source exist at the same time. In simulated domestic sewage, the specific growth rate and oil yield can reach 0.0033d-1 and 6.96 mg/ (Ld), pollutant removal rate of more than 95% respectively. Grinding, ultrasonic, repeated freezing and thawing and acid heat can achieve different degrees of cell wall breaking effect, among which ultrasonic treatment can achieve the highest broken wall rate of 65.25%. Of the four organic solvents, ethanol was the most effective solvent, and the maximum oil yield of 22.00%. Chlorella sp. was obtained at 60.C. C16 and C18 are the main fatty acids, and the polyunsaturated fatty acid content is relatively low, which can meet the standard of some commercial biodiesel. In addition, the composition and content of fatty acids were affected by different extraction solvents and culture conditions. Therefore, we can select organic solvents and culture conditions to optimize the quality of biodiesel products.
【学位授予单位】：大连理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TE667
【参考文献】
相关期刊论文 前1条
1 苏贞峰;薛升长;康瑞娟;石绍渊;丛威;蔡昭玲;;平板式光生物反应器培养液混合强度对螺旋藻生长的影响[J];中国生物工程杂志;2009年03期
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