标题: | 微藻养殖模组用于工业废气和畜产沼气中二氧化碳的捕捉并利用于微藻生物质的生产与生质气体的提纯 Microalgae culture modules for capturing the carbon dioxide in flue gas and livestock biogas to produce microalgal biomass and upgrade biogas |
作者: | 高千雅 Kao, Chien-Ya 林志生 Lin, Chih-Sheng 生物科技系所 |
关键字: | 微藻;小球藻;二氧化碳再利用;工业废气;沼气;microalgae;Chlorella;carbon dioxide utilization;flue gas;biogas |
公开日期: | 2013 |
摘要: | 微藻养殖可用于废气中二氧化碳(CO2)的减量,以及废气中部份有毒气体的减除,而所养殖的微藻细胞中油脂则可被萃取与转化为生质柴油,据此微藻养殖同时具备有减碳、减废、生产生物质能等多重效应。本研究中,我们利用化学突变处理与驯养方式,分离得到可分别耐受工业废气与畜牧沼气之微藻Chlorella sp.突变株,并探讨通入不同种类的工业废气和畜牧沼气用于微藻养殖对其生长效能,生物质和油脂产量,以及油脂组成的影响。此外,我们也建构了一户外型的光生物微藻养殖模组,搭配自动气体切换操作程序,探讨户外实场大规模微藻养殖用以沼气提纯(upgrading)和工业废气中CO2减量的效能。 在利用工业废气的研究中,Chlorella sp. MTF-15微藻株和中国钢铁公司烟道气被用于各项实验。烟道气来源有三种,分别为炼焦炉(主要组成23-27% CO2、70-80 ppm NOX及80-90 ppm SO2)、高炉(24-28% CO2、8-10 ppm NOX及15-20 ppm SO2)及动力场(22-26% CO2、25-30 ppm NOX及15-20 ppm SO2),以这三种工业废气进行室内Chlorella sp. MTF-15养殖时,微藻具有相似的生长趋势,而在通入废气与空气混合稀释比例约1/4或1/2时,微藻具有较高的生长潜能。Chlorella sp. MTF-15通入炼焦炉、高炉及动力场工业废气养殖后,其最大比生长速率与油脂产量分别为0.827、0.762及0.728 d-1与0.668、0.961及0.792 g/L,通入工业废气养殖之微藻的C16:0 + C18:1(适合用于生产生质柴油之脂肪酸)含量约为60-65%,其中通入动力场废气所养殖之微藻的C18:1含量明显高于通入炼焦炉与高炉工业废气者。Chlorella sp. MTF-15对于炼焦炉、高炉及动力场废气中CO2的最佳移除效率分别约为25%、40%及50%;对于炼焦炉废气中NOX与SO2的移除效率约为65%与40%,对于高炉与动力场废气中NOX与SO2的移除效率为> 80%与> 90%。上述结果显示,微藻Chlorella sp. MTF-15的生长潜能、油脂产量及脂肪酸组成取决于工业废气中的主要气体组成和微藻养殖模组的操作模式,例如工业废气的稀释比例。 在利用畜牧沼气中CO2之研究中,由于畜牧废水经厌氧发酵处理后除了产生含有高浓度甲烷(CH4)之沼气外,也常伴随着大量的惰性气体CO2的产生,因此若要有效的将沼气应用在引擎燃料上,势必要先降低沼气中CO2的浓度以提升沼气中CH4的浓度。为了使微藻于沼气中仍保有其生长潜能,我们分离筛选得一株可耐受沼气之微藻突变株Chlorella sp. MB-9。Chlorella sp. MB-9在通有H2S < 100 ppm和80% CH4的环境之下,相较对照组仍具有70%以上的生长潜能。在实场的户外操作实验中,通入分别为0.05、0.1、0.2及0.3 vvm流量之除硫沼气(~20% CO2、~70% CH4及H2S < 50 ppm),Chlorella sp. MB-9的最高生长率分别为0.320、0.311、0.275及0.251 g/L/d。为了提纯沼气,我们利用所建立的户外光生物微藻养殖模组,搭配了自动气体切换程序用于实场微藻养殖试验,而结果显示沼气中的CO2之移除效率能持续维持在50%以上,而CH4的浓度从起始的70%提升至85-90%。 综上所述,我们的实验结果证实Chlorella sp. MTF-15与MB-9能直接并有效地利用不同的工业废气或畜牧沼气中的CO2,以作为微藻生长的营养源并生产生物质与脂质。此外,我们所建立之吨级规模的具有自动气体切换操作功能的户外光生物反应系统,能有效率地作为一连续式的工业废气的生物移除或沼气提纯之CO2捕捉的微藻养殖模组系统。这些结果皆证实了利用微藻进行生物固碳是一个具有潜力的方法,不仅能有效的用来减除工业废气中CO2的排放、提升沼气中CH4的浓度,还能生产富含油脂之微藻生物质作为再生能源的料源。 Microalgal cultivation can be used for CO2 and toxic gases mitigation from waste gas and microalgal lipids can be extracted and converted into biodiesel. Accordingly, there are multiple effects such as carbon reduction, waste remediation and biomass production in microalgae cultivation. In this study, using chemical random mutagenesis and domestication, we isolated mutant strains of microalgae Chlorella sp., which were tolerant to flue gas and biogas, respectively. The growth characterization, biomass production, lipid production and lipid composition of Chlorella sp. mutant strains aerated with different kind of gases were investigated. We also established outdoor microalgae-incorporating photobioreactor culture system with a gas cycle-switching operation, which could be continuously used as a CO2 capture model for biogas upgrading or flue gas remediation. In the study of flue gas utilization by microalgal mutant strain, Chlorella sp. MTF-15, aerated with different kind of flue gases from a steel plant, the China Steel Corporation in Taiwan were investigated. There three kind of the flue gases were generated from the coke oven (major components: 23-27% CO2, 80 ppm NOX and 90 ppm SO2), hot stove (24-28% CO2, 10 ppm NOX and 20 ppm SO2) and power plant (22-26% CO2, 30 ppm NOX and 20 ppm SO2). Growth profiles of the microalgal cultures aerated with three different kinds of flue gases were similar and show a higher growth potential at the aeration by 1/4 or 1/2 flue gas dilution ratios than that of with air. The maximum specific growth rate and lipid production of the Chlorella sp. MTF-15 aerated with flue gas from coke oven, hot stove and power plant were 0.827, 0.762 and 0.728 d-1, and 0.668, 0.961 and 0.792 g/L, respectively. The content of C16:0 + C18:1 (the suitable fatty acids for biodiesel production) of the Chlorella sp. MTF-15 cultures aerated with the flue gases was approximately 60-65%. However, C18:1 content of the lipid of Chlorella sp. MTF-15 culture aerated with power plant flue gas was significantly higher than those aerated with coke oven and hot stove flue gases. The optimal CO2 removal efficiency of coke oven, hot stove and power plant flue gas by Chlorella sp. MTF-15 cultures was around 25%, 40% and 50%, respectively. In addition, the NOX and SO2 removal efficiency of coke oven, hot stove and power plant flue gas by Chlorella sp. MTF-15 cultures were approximately 65% and 40% aerated with coke oven flue gas, and > 80% and > 90% aerated with hot stove and power plant flue gases. Those results suggest that growth potential, lipid production and fatty acid composition of the microalgal Chlorella sp. MTF-15 cultures are dependent on the composition of flue gas used and the module operation, at least including flue gas dilution, of the microalgal cultures. In the study of carbon dioxide utilization in livestock biogas, the livestock biogas was produced from anaerobic swine wastewater treatment contains high methane (CH4) but high carbon dioxide (CO2). The presence of high content of CO2, an incombustible gas, in biogas should be mitigated as high calorific value fuel gas. In this study, we isolated a biogas tolerance mutant strain of microalga, Chlorella sp. MB-9. The microalgal mutant strain, Chlorella sp. MB-9, can grow in the presence of gas containing H2S < 100 ppm, and the growth capacity of the microalgal culture aerated with 80% CH4 was approximately 70% of that of the control culture (0% CH4). In the field study of outdoor operation, the maximum growth rates of Chlorella sp. MB-9 aerated with desulfurized biogas (~20% CO2, ~70% CH4 and H2S < 100 ppm) at 0.05, 0.1, 0.2 and 0.3 vvm were 0.320, 0.311, 0.275 and 0.251 g/L/d. To upgrade biogas produced from the anaerobic digestion of swine wastewater, and outdoor photobioreactor was established. The outdoor microalgae-incorporating photobioreactor culture system with a gas cycle-switching operation could be continuously used as a CO2 capture model for biogas upgrading. Furthermore, our field study demonstrated that the efficiency of CO2 capture from biogas could be maintained at 50% on average, and the CH4 concentration in the effluent biogas from the Chlorella cultures increased from its original 70% up to 85-90%. In summary, our experimental results mentioned above confirm that Chlorella sp. MTF-15 and MB-9 can efficiently and directly utilize the CO2 in different kinds of flue gases or livestock biogas for microalgal growth, then produce biomass and lipid. In addition, the established outdoor photobioreactor system using a gas cycle-switching operation could be used as a continuously CO2 capture model for flue gas bioremediation and biogas upgrading. Those results are confirmed that the microalgae-based CO2 biological fixation is regarded as a potential way to not only reduce CO2 emission but also achieve to produce lipid-rich microalgal biomass as a regenerative energy source. |
URI: | http://140.113.39.130/cdrfb3/record/nctu/#GT079828801 http://hdl.handle.net/11536/74426 |
显示于类别: | Thesis |