耐砷铁氧化菌的除砷特征及其机理研究

发布时间：2018-04-29 10:17

本文选题：铁氧化菌 + 生物成因　；参考：《中国地质大学(北京)》2016年博士论文

【摘要】：砷是一种自然界中常见的有毒物质,其通过世界范围内广泛分布的高砷地下水威胁成千上万人的身体健康,对高砷水进行处理显得尤为重要。高砷地下水往往含有较高浓度的亚铁离子,因此利用铁氧化菌氧化亚铁离子产生的铁氧化物矿物除砷是目前除砷领域研究的热点之一。本文以好氧菌Pseudomonas sp.strain GE-1和厌氧菌Pseudogulbenkiania sp.strain 2002为研究对象,利用室内实验,研究了这两株菌的氧化Fe(II)特征和机理,揭示了在不同除砷条件下铁氧化菌氧化Fe(II)过程的除砷效果和影响因素,并利用谱学手段揭示了除砷机理。Strain GE-1的亚铁氧化过程以硝酸盐作为电子受体,生成弱结晶的两线水铁矿。高浓度砷存在时,特别是As(III)存在时,strain GE-1的亚铁氧化过程、能量物质ATP的变化以及硝酸盐的还原等出现滞后现象。不论As(III)还是As(V),都可以被GE-1介导的共沉淀和吸附过程有效地去除。共沉淀过程对As(V)的去除效果较好,而吸附过程则对As(III)的去除效果较好。培养液中砷形态的检测显示,共沉淀过程中As(V)被还原成As(III),而吸附过程则没有检测到As(V)的还原。在无氧条件下,strain GE-1介导产生的两线水铁矿对砷的吸附符合假二级动力学模型,扩散过程是吸附过程的主要控制步骤,在此过程中没有观察到As(III)的氧化或As(V)的还原。然而,在好氧条件下,无论是共沉淀还是吸附过程,As(III)在GE-1诱导产生的水铁矿表面均被氧化成As(V)。Strain 2002具有很强的耐砷能力,特别是As(V),其最大As(V)的耐受能力约为1000 mg/L。当有高浓度的砷存在时,strain 2002的形貌趋于变短。非生长条件下strain 2002可以迅速氧化亚铁,并产生纤铁矿沉淀,而且在不改变砷形态的情况下,有效去除培养液中的As(III)和As(V)。当初始Fe/As保持不变时,较高初始浓度的亚铁产生较好的除砷效果,并使砷在纤铁矿表面的覆盖度升高。X射线精细结构结果表明,当固定初始As(III)或As(V)浓度时,初始亚铁浓度的改变并不影响砷的表面络合模式(双齿双核共角表面络合)。当固定初始亚铁浓度时,初始As浓度的升高导致砷在纤铁矿中的表面覆盖度升高;其中,As(III)表面覆盖度的升高与双齿双核共角表面络合模式和双齿单核共边表面络合模式的共存有关;而As(V)表面覆盖度的升高是双齿双核共角表面络合模式和单齿单核共边表面络合模式共存的结果。无论是好氧菌GE-1还是厌氧菌strain 2002,其亚铁氧化过程都具有很好的除砷效果,并且这两种菌的生长都可以利用硝酸盐作为电子受体,这给砷-硝酸盐共污染水体的原位治理提供了非常有效的潜在治理方案。
[Abstract]:Arsenic is a common toxic substance in nature. It threatens the health of thousands of people through the widespread distribution of high arsenic groundwater in the world, so it is particularly important to treat high arsenic water. High arsenic groundwater often contains high concentration of ferrous ions, so iron oxide minerals produced by ferric oxide oxidized by ferric oxide bacteria are one of the hot spots in the field of arsenic removal. In this paper, using aerobic Pseudomonas sp.strain GE-1 and anaerobes Pseudogulbenkiania sp.strain 2002 as research objects, the characteristics and mechanism of FeII oxidation of these two strains were studied by laboratory experiments, and the effect of removing arsenic and influencing factors on the oxidation of FeII by ferric oxidizing bacteria under different arsenic removal conditions were revealed. The mechanism of arsenic removal in ferrite oxidation process of Strain GE-1 was revealed by means of spectroscopic method. Nitrates were used as electron receptors to form weakly crystallized two-wire hydrite. In the presence of high concentration of arsenic, especially in the presence of As-III, the process of ferrous oxidation of strain GE-1, the change of ATP, and the reduction of nitrate are delayed. Both ASI and ASV can be effectively removed by GE-1 mediated coprecipitation and adsorption processes. The coprecipitation process has a better removal efficiency of ASV, while the adsorption process has a better removal effect of AS-III. The determination of arsenic forms in the culture medium showed that during the coprecipitation process, AsHV was reduced to AsHIIIN, but no reduction was detected during the adsorption process. The adsorption of arsenic by two-wire water ore induced by strain GE-1 under anaerobic conditions accords with the pseudo-second-order kinetic model. The diffusion process is the main control step of the adsorption process, and no oxidation of AsHI-III or reduction of As-V) is observed in this process. However, under aerobic conditions, both coprecipitation and adsorption processes have been oxidized to As(V).Strain 2002 on the surface of the water ore induced by GE-1. It is found that As(V).Strain 2002 has a strong arsenic tolerance, especially the maximum aspartic V (1000 mg / L). The morphology of strain 2002 tends to be shorter in the presence of high concentration of arsenic. Under non-growth condition, strain 2002 can oxidize ferrous rapidly and produce pyrite precipitate. Without changing the arsenic form, strain 2002 can effectively remove the ascorbic acid and ascorbic acid in the culture medium. When the initial Fe/As remained constant, the high initial concentration of ferrous produced a better arsenic removal effect, and the coverage of arsenic on the surface of the fiberite was increased. The results of X-ray fine structure showed that when the initial concentration of as II I or AsV) was fixed, The change of initial ferrous concentration does not affect the surface complexation mode of arsenic. When the initial ferrous concentration is fixed, the increase of as concentration leads to the increase of surface coverage of arsenic in pyrite. The increase of the surface coverage is related to the coexistence of the co-angular surface complexation mode and the co-edge surface complexation mode of the bicententate mononuclear. However, the increase of surface coverage is the result of the coexistence of the coplanar surface complexation mode of double-tooth binuclear and single-toothed mononuclear coplanar surface complexation mode. Both aerobic GE-1 and anaerobes strain 2002 have a good arsenic removal effect in the process of ferrous oxidation, and the growth of both bacteria can use nitrate as an electron receptor. This provides a very effective and potential treatment scheme for arsenic-nitrate co-polluted water in situ treatment.
【学位授予单位】：中国地质大学(北京)
【学位级别】：博士
【学位授予年份】：2016
【分类号】：X52;X172

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