中草药残渣好氧厌氧耦合发酵产甲烷特性

发布时间：2018-01-11 06:11

本文关键词：中草药残渣好氧厌氧耦合发酵产甲烷特性　出处：《东北农业大学》2015年硕士论文　论文类型：学位论文

【摘要】：在中国中草药残渣(Chinese Herb-extraction Residues,CHER)的年产量在100万吨以上,是一种重要的固体有机废弃物。中草药工业的迅猛发展给我国经济发展城镇化建设做出了贡献,而与此同时在中草药生产过程中产生的CHER也给生态环境带来不可忽视的压力。CHER中富含糖类、甙类、葱酮、木质素、生物碱、靴质和粗蛋白等有机化合物,如处理不当会对周边生态环境造成严重打击。目前针对CHER比较常见的处理方式是卫生填埋和焚烧,然而这些处理方式会不可避免的对周边地下水源、土壤和空气造成二次污染。与此同时,CHER也是一种能够被厌氧微生物降解发酵利用的生物质资源,但CHER中中性洗涤纤维(NDF)约占50%左右,由于木质素的物理屏蔽作用,阻碍了微生物细胞胞外酶与纤维素、半纤维素的接触,限制CHER中纤维素、半纤维素的水解速率,导致其厌氧发酵过程缓慢,VS产甲烷率较低。可见木质素的降解是水解酸化的首要步骤,而木质素最初的裂解需要分子氧的存在,未经过好氧处理的木质素几乎不能在厌氧环境下被微生物降解。为此将厌氧发酵分成两相进行,即首先对CHER进行中温好氧水解产酸发酵,之后进行产甲烷发酵试验,并且将不同种类的中草药残渣(CHER)的单相厌氧产甲烷发酵过程与好氧厌氧两相耦合产甲烷发酵过程进行对比,将过程中甲烷累积产量、VS甲烷产率、日产甲烷量以及TS降解率等参数进行深入的对照研究。结果表明:(1)好氧厌氧两相耦合发酵模式对改善两种CHER产甲烷潜能提高厌氧发酵的累积甲烷产量、VS甲烷产率和日产甲烷量均有显著效果,对累积甲烷产量最大提升率为35.7%,对VS甲烷产率的最大提升率为31.1%,对日产甲烷量的最大提升率为52.4%。(2)好氧水解酸化微生物能够有效的破坏木质素的物理屏蔽使更多的纤维素、半纤维素被降解,好氧厌氧耦合发酵模式相对于单相厌氧发酵对两种CHER的TS降解率有显著的提升。(3)不同好氧水解发酵时长对两种CHER厌氧产甲烷发酵的各项指标的提升差别显著。在本试验中在对两种中草药残渣好氧水解酸化发酵24h时,CHER-A的累积甲烷产量提升了30.9%,VS甲烷产率提升了23.6%,最大日产甲烷量提升了25.5%,底物TS降解率提升到37.9%;CHERB的累积甲烷产量提升了35.7%,VS甲烷产率提升了31.1%,最大日产甲烷量提升了52.4%,底物TS降解率提升到了40.0%。所以,在好养厌氧耦合发酵模式中好氧水解酸化发酵相的最佳运行时长为24小时。
[Abstract]:The annual output of Chinese Herb-extraction residuesCher is more than 1 million tons. Chinese herbal medicine industry is an important solid organic waste. The rapid development of Chinese herbal medicine industry has contributed to the development of urbanization in China. At the same time, the CHER produced in the production process of Chinese herbal medicine also brought the ecological environment a pressure that can not be ignored. Cher is rich in sugar, glycosides, onion ketones, lignin, alkaloids. Organic compounds such as boot and crude protein, such as improper treatment, will cause serious damage to the surrounding ecological environment. At present, sanitary landfills and incineration are the most common treatment methods for CHER. However, these treatments will inevitably cause secondary pollution to the surrounding groundwater, soil and air. At the same time, Cher is also a biomass resource that can be degraded and fermented by anaerobic microorganisms. However, the neutral washing fiber (NDF) accounted for about 50% in CHER. Because of the physical shielding of lignin, the contact of extracellular enzymes with cellulose and hemicellulose in microbial cells was hindered. Limiting the hydrolysis rate of cellulose and hemicellulose in CHER resulted in a low methanogenic rate of VS during anaerobic fermentation. It can be seen that the degradation of lignin is the first step of hydrolysis and acidification. However, the initial decomposition of lignin requires the presence of molecular oxygen, and the lignin without aerobic treatment can hardly be degraded by microorganisms in anaerobic environment. Therefore, anaerobic fermentation is divided into two phases. That is to say, CHER was first hydrolyzed by medium temperature aerobic acid-producing fermentation, and then methanogenic fermentation was carried out. The single-phase anaerobic methanogenic fermentation process was compared with the aerobic anaerobic two-phase coupling methanogenic fermentation process, and the cumulative methane production and the methane production rate were compared. The methane-producing amount and the degradation rate of TS were studied in detail. The results showed that the ratio of Ch _ 4 to T _ 2O _ 1 was 1). Aerobic anaerobic two-phase coupling fermentation model improved the methane production potential of two kinds of CHER and increased the cumulative methane production of anaerobic fermentation. Both the methane production rate and the daily methane production rate of vs were significant, the maximum promotion rate of cumulative methane production was 35.7%, and the maximum promotion rate of vs methane production rate was 31.1%. Aerobic hydrolytic acidification microorganisms can effectively destroy the physical shielding of lignin so that more cellulose hemicellulose is degraded. Compared with single-phase anaerobic fermentation, the aerobic anaerobic coupling fermentation mode significantly improved the TS degradation rate of two CHER. There were significant differences between the two CHER anaerobic methanogenic fermentation indexes with different aerobic hydrolytic fermentation time. In this experiment, the aerobic hydrolytic acidification fermentation of the residue of the two Chinese herbal medicines was carried out for 24 hours. The cumulative methane production of CHER-A increased by 30.9 and vs methane production increased by 23.6am, the maximum daily methane production increased by 25.5, and the TS degradation rate of substrate increased to 37.9; The cumulative methane production of CHERB increased by 35.7% and the methane yield of vs increased by 31. 1 and the maximum daily methane production increased by 52.4%. The TS degradation rate of substrate was increased to 40. 0%. Therefore, the optimal operating time of aerobic hydrolytic acidified fermentation phase was 24 hours in the aerobic anaerobic coupling fermentation model.
【学位授予单位】：东北农业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X787;TQ221.11

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