铁基材料对厌氧氨氧化启动过程及微生物群落影响研究

发布时间：2018-09-04 11:14

【摘要】：厌氧氨氧化工艺作为一种新型脱氮工艺,该工艺以氨氮为电子受体,亚硝态氮为电子供体,在厌氧氨氧化菌的作用下直接生成N2,同时也因该工艺无需外加碳源、无需曝气、工艺流程短、无N2O产生等优点受到了广泛的关注。但该工艺同时也有如下的缺点:(1)厌氧氨氧化菌增长速度缓慢,其世代周期通常为11天以上,导致该工艺在实际应用中启动时间较为漫长;(2)厌氧氨氧化菌对外界环境较为敏感,pH、DO、温度、游离亚硝酸浓度等都会影响微生物的活性和脱氮效果;(3)总氮去除效果有待提高。从厌氧氨氧化工艺发现到现在共有20多年的时间,研究人员们都致力于缩短该工艺的启动时间和在极端条件下启动该工艺,他们从反应器类型的选择、接种污泥种类的选择、载体的选择、及控制操作条件上入手,试图得到快速启动厌氧氨氧化工艺启动的最佳条件。有研究表明,加入零价铁可以通过还原掉反应器中的DO来为微生物的生存提供一个良好的环境,从而在促进微生物富集的同时,也可以还原厌氧氨氧化反应生成的硝态氮,来达到更好的脱氮效果快速启动厌氧氨氧化过程。磁铁矿通过为微生物提供弱磁场和铁离子,来提高微生物的活性,并且还可以作为载体使微生物附着在其上生长,形成颗粒污泥。本论文将从投加载体的角度入手,探究不同浓度的零价铁和磁铁矿在厌氧氨氧化工艺快速启动过程中对脱氮效果和微生物群落分布的影响。主要结论如下:(1)50 mg/L和1000 mg/L的零价铁可以分别将厌氧氨氧化工艺的启动时间从102天缩短至84天和90天。并且水质结果和qPCR结果显示,在反应器运行初期阶段,1000 mg/L的零价铁对微生物有抑制作用,过了 50天后,微生物开始适应高浓度零价铁的环境,同时零价铁也开始促进微生物的活性和富集。在反应器中投加零价铁可以促进厌氧氨氧化菌的富集,第120天的qPCR结果显示,空白对照组的厌氧氨氧化菌的拷贝数为8.73×107copies/ng,而投加有50m/L和1000 mg/L零价铁的反应器中的拷贝数分别为1.26×108 copies/ng和1.34×108 copies/ng。(2)与空白对照组(4.87μmol/L)相比较,加有零价铁的反应器中的N20生成量较低(加有50 mg/L零价铁反应器中为3.76 μmol/L,1000 mg/L零价铁中为3.24 μmol/L),同时与N2O生成相关的nosZ基因的拷贝数分别为1.48×106 copies/ng(空白对照组)、6.33×105 copies/ng(50mg/L零价铁反应器)、1.09×106 copies/ng(1000 mg/L零价铁反应器),因此零价铁可以抑制N20的生成。(3)高通量测序结果显示,零价铁既可以影响微生物群落的多样性,也可以影响浮霉菌门和变形菌门下的微生物下数量与分布,并且根据在属的范围上分类结果,厌氧氨氧化菌中CandidatusBrocadia属的适应性更强,更容易富集。(4)磁铁矿可以缩短厌氧氨氧化启动初期内源反硝化阶段所用的时间,而且可以将总氮去除率从59.3%提高到65.8%,同时在增加氮负荷的过程中,反应器也体现出一定的抗冲击负荷能力。第150天时,磁铁矿反应器中的厌氧氨氧化菌的拷贝数为2.59± 0.009×108 copies/ng,占全菌比例为58.88%,而对照组中为2.44±0.004×108 copies/ng,占全菌比例为57.35%,说明磁铁矿更有利于厌氧氨氧化菌的富集。(5)同时磁铁矿反应器中的N2O释放量(25.06±15.27μmol/L)与nosZ拷贝数(2.26×106±2.93×104 copies/ng)显示磁铁矿可以通过抑制nosZ的数量来减少N2O的产生。(6)高通量测序结果表明,经过一段时间的培养,反应器中微生物多样性降低,同时加有磁铁矿的反应器可以富集丰度较高的为CandidatusJettenia,而空白对照组则能富集丰度较高的Gandidatus Brocadia,这表明微生物受环境影响比较大,特定的生存环境能够富集和选择特定微生物。
[Abstract]:Anaerobic ammonia oxidation process is a new type of denitrification process. It uses ammonia nitrogen as electron acceptor and nitrite nitrogen as electron donor to produce N2 directly under the action of anaerobic ammonia oxidation bacteria. At the same time, this process has attracted wide attention because of its advantages such as no additional carbon source, no aeration, short process flow and no N2O production. There are the following shortcomings: (1) anaerobic ammonia-oxidizing bacteria grow slowly, its generation cycle is usually more than 11 days, resulting in a longer start-up time in practical application; (2) anaerobic ammonia-oxidizing bacteria are more sensitive to the external environment, pH, DO, temperature, free nitrite concentration, etc. will affect the microbial activity and denitrification effect; (3) total nitrogen removal Since the discovery of the anaerobic ammonia oxidation process, researchers have been working to shorten the start-up time and start the process under extreme conditions. Studies have shown that adding zero-valent iron can provide a good environment for microorganisms to survive by reducing the DO in the reactor, thus promoting microbial enrichment and reducing nitrate nitrogen produced by anaerobic ammonia oxidation reaction to achieve better denitrification. Magnetite improves the activity of microorganisms by providing weak magnetic field and iron ions for microorganisms. Magnetite can also be used as a carrier to attach microorganisms to grow on it and form granular sludge. This paper will explore the anaerobic effect of different concentrations of zero-valent iron and magnetite from the point of view of loading body. The main conclusions are as follows: (1) 50 mg/L and 1000 mg/L zero-valent iron can shorten the start-up time of anaerobic ammonia oxidation process from 102 days to 84 days and 90 days respectively. After 50 days, the microorganisms began to adapt to the environment of high concentration of zero-valent iron, and zero-valent iron also began to promote the activity and enrichment of microorganisms. The number of copies in the reactor with 50 m/L and 1000 mg/L zero valent iron was 1.26 x 108 copies/ng and 1.34 x 108 copies/ng, respectively. (2) Compared with the blank control group (4.87 micromol/L), the production of N20 in the reactor with zero valent iron was lower (3.76 micromol/L, 100 micromol/L in the reactor with 50 mg/L zero valent iron). The copies of nosZ genes related to N2O production were 1.48 *106 copies/ng (blank control group), 6.33 *105 copies/ng (50mg/L zero-valent iron reactor) and 1.09 *106 copies/ng (1000 mg/L zero-valent iron reactor), respectively. Therefore, zero-valent iron could inhibit the formation of N20. Valence of iron can affect not only the diversity of microbial communities, but also the number and distribution of flounder and deformed bacteria. According to the classification results in the genus range, the Candidatus Brocadia is more adaptable and easier to enrich. (4) Magnetite can shorten the start-up period of anaerobic ammonia oxidation. The total nitrogen removal rate was increased from 59.3% to 65.8% during the denitrification stage, and the reactor also showed a certain impact resistance during the process of increasing nitrogen load. In the control group, the ratio of 2.44 0.004 65 (6) The results of high-throughput sequencing showed that the microbial diversity in the reactor decreased after a period of cultivation, and the reactor with magnetite could enrich Candidatus Jettenia with higher abundance, while the blank control group could enrich Gandidatus Brocadia with higher abundance, which indicated that the microorganisms were affected by environmental factors. The established living environment can enrich and select specific microorganisms.
【学位授予单位】：山东大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X703

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