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应用锰氧化菌修复环境中砷、锑和有机复合污染物应用锰氧化菌修复环境中砷、锑和有机复合污染物
王华伟
学位类型博士
导师潘响亮
2015
学位授予单位中国科学院大学
学位授予地点北京
学位专业生态学
关键词锰氧化菌 生物锰氧化物 重金属 有机污染物
摘要新疆干旱半干旱地区的水环境目前正面临重金属和持久性有机物等复合污染的问题,是新疆地区发展所面临和亟待解决的重大环境问题之一。锰氧化菌诱导形成生物锰氧化物,即在好氧条件下,锰氧化菌以Mn(II) 为电子供体,将溶解性Mn(II) 转化为不溶的Mn(IV) 氧化物的过程,因其特殊的产生途径及氧化产物,该过程为水环境中重金属和有机复合污染的修复提供了一种新思路。本论文以锰氧化菌Pseudomonas putida strain MnB1为实验菌株,通过批实验、电化学实验,以及生物反应器等实验方法,研究了锰氧化菌胞外成矿机制,以及其对砷、锑、四环素类和氯代苯酚类目标污染物的修复效果,主要研究结果如下: (1) 通过扫描电镜-能谱仪 (SEM-EDS)、X-射线光电能谱 (XPS) 和Zeta 电位等技术手段确定了生物锰氧化物的结构特征;通过酶学实验初步证实超氧自由基 (·O2-)在P. putida strain MnB1氧化二价锰过程中起到重要作用,同时阐明了P. putida strain MnB1在生长和锰氧化过程中H2O2的产生特征。此外,外加低浓度的H2O2 (≤100 μM)时对生物锰氧化物的产生影响不显著;细菌胞外物质 (EPS) 加速了P. putida strain MnB1的锰氧化过程,表明细菌EPS在锰氧化过程中起到重要作用;腐殖质和光照对P. putida strain MnB1的锰氧化过程的影响不显著。 (2) 通过批实验、电化学实验、SEM-EDS和红外光谱仪 (FTIR) 等实验技术手段证实了EPS在自然碳酸锰矿物的锰氧化过程中起重要作用,具体作用机制:P. putida strain MnB1能够快速有效的氧化和溶解自然碳酸锰矿物而形成生物锰氧化物;EPS加速了二价锰的溶出速率;溶液中pH值、EPS浓度、离子强度和锰矿用量等水化学因素显著影响二价锰的溶出速率;EPS中多糖或蛋白中的N-H、C=O和C-H 等官能团参与自然碳酸锰矿物的溶解过程;通过塔菲尔极化曲线法和电化学阻抗谱法等电化学手段也证实了EPS在加速自然碳酸锰矿溶解时起到重要作用。 (3) 生物锰氧化物和δ-MnO2均能同时有效的去除溶液中的三价砷和盐酸四环素,是该类废水修复的理想材料。生物锰氧化物对盐酸四环素的去除效率较δ-MnO2和商业二氧化锰能够提高3-6倍;三价砷和盐酸四环素的去除效率随锰氧化物的用量的增加而显著提高,而高浓度的盐酸四环素和三价砷会竞争锰氧化物的氧化或吸附点位,最终影响两种污染物的去除效果;利用高效液相色谱-质谱 (HPLC-MS) 技术,分析辨别了盐酸四环素的降解中间产物,推测了盐酸四环素的可能降解机制。 (4) 对比细菌生长过程和锰氧化过程可知,锰氧化过程对2, 4二氯苯酚 (DCP) 的去除起主导作用;2, 4二氯苯酚的去除率随着生物锰氧化物浓度的增加而显著提高;生物反应器实验表明,细菌锰氧化过程能够显著提高底泥中2, 4二氯苯酚的去除,而砷的可交换态含量显著较少,铁锰氧化物结合态含量明显增高,表明细菌锰氧化过程增加了砷的稳定性;由HPLC-MS分析可知,2, 4二氯苯酚经脱氯和羟基化形成中间产物偏苯三酚 (HHQ),偏苯三酚进一步被氧化为小分子有机物。 (5) 通过对比研究生物锰氧化物对Sb(III) 和 Sb(V) 的截留作用可知:存在生物锰氧化物条件下,不同浓度的Sb(III) 在10 min之内被快速氧化,而生物锰氧化物对不同浓度的Sb(V) 基本没有去除作用;XPS表明Sb(III) 与生物锰氧化物反应后,Sb(V) 是主要的固相形态,此外,化学抽提实验表明Sb(V) 主要以锰氧化物结合态或更稳定的形态存在;X-射线衍射仪 (XRD) 结果表明Sb(III) 与生物锰氧化物反应后形成稳定的锑酸锰矿物 (Mn2Sb2O7);生物锰氧化物中的细菌活性对Sb(III) 具有明显的截留作用,而对Sb(V) 几乎没有作用。 (6) 通过对比研究石英砂负载生物锰氧化物-生物碳两阶段反应器对砷和锑的去除效果可知:石英砂负载生物锰氧化物柱能有效的转化废水中的三价砷和锑为低毒性的五价砷和锑,降低砷和锑的毒性,反应前期生物锰氧化物对砷和锑的截留率较高;生物炭柱对砷的去除的贡献率随反应进行逐渐提高,而对锑的修复效果不佳;石英砂负载生物锰氧化物-生物碳对砷保持较高的去除效果,修复效果要明显好于锑。
其他摘要In Xinjiang arid and semi-arid regions, water environments are facing combined pollutions including heavy metals and persistent organic matters. It is also one of hot environmental issues which should be faced and resolved in the development of Xinjiang Uygur Autonomous Region. Biogenic Mn oxides produced by Mn(II) oxidation bacteria, namely, Mn(II) oxidation bacteria can oxidize dissolved Mn(II) into insoluble Mn(IV) oxides under aerobic conditions. Due to the special metabolic pathways and metabolic products, this process provides a new approach for the remediation of heavy metals and organic combined pollutants in water environments. The aims of this research were to investigate the formation mechanisms of extracellular biogenic Mn oxides generated by Pseudomonas putida strain MnB1 and the removal efficiency of the targeted pollutants (e.g., arsenic, antimony, tetracyclines and chlorophenols) through batch experiments, electrochemical experiments and bioreactor experiments. The main conclusions were as follows: (1) The structural feature of biogenic Mn oxides was determined by SEM-EDS, XPS and Zeta potential. Superoxide radical produced by P. putida strain MnB1 played an important role in oxidation of Mn(II). Meanwhile, we also clarified the production characteristics of H2O2 during bacterial growth and oxidation of Mn(II). Moreover, the addition of H2O2 (≤100 μM) showed no obvious effect on bacterial Mn(II) oxidation process. EPS from P. putida strain MnB1 accelerated the bacterial Mn(II) oxidation process, and this indicated that EPS played a key role in bacterial Mn(II) oxidation process. Also, Mn(II) oxidation process was not significantly influenced by addition of humic substances and treatment of light. (2) Through batch experiments, electrochemical experiments, SEM-EDS and FTIR analysis, it was confirmed that bacteria EPS played a vital role in increasing the dissolution of natural rhodochrosite, and the specific mechanism were as follows. P. putida strain MnB1 cells could dissolve natural rhodochrosite effectively and subsequently oxidize liberated Mn(II) ions to form Mn oxides. Bacterial EPS increased the dissolution rate of natural rhodochrosite, and the dissolution rate was obviously influenced by water chemistry factors, such as pH, ionic strengths, EPS concentrations and rhodochrosite dosages. Functional groups like N-H, C=O and C-H in the polysaccharide or proteins of EPS were involved in the dissolution of natural rhodochrosite. In addition, EPS was confirmed to play a key role in increasing dissolution of natural rhodochrosite mineral based on electrochemical methods such as Tafel and EIS. (3) Biogenic Mn oxides and δ-MnO2 could remove tetracycline hydrochloride (TC) and As(III) simultaneously, and both materials had a potential application for wastewater treatment. The removal efficiency of TC using biogenic Mn oxides was 3-6 times higher than δ-MnO2 and commercial MnO2. The removal efficiencies of TC and As(III) were positively increased with the initial Mn oxides dosage, however, high concentrations of TC and As(III) competed with each other for oxidation or adsorption sites and thus affected the removal efficiencies of both contaminants. The intermediates and products of TC were identified by high performance liquid chromatography-mass spectrometry (HPLC-MS), and the degradation pathway of TC by δ-MnO2 was proposed. (4) Compared with process of bacterial growth and bacterial Mn(II) oxidizing process, it was that the latter one played a key role in 2, 4-dichlorophenol (DCP) removal. The removal efficiency of DCP was increased with biogenic Mn oxides concentrations. Biogenic Mn(II) oxidizing process could significantly accelerate the removal of DCP in sediments from the bioreactor experiments. Meanwhile, this process reduced the exchangeable fraction of arsenic and increased the fraction of Fe-Mn oxides bound. This mean that bacterial Mn(II) oxidizing process could increase the stability of arsenic. According to the HPLC-MS analysis, it was found that DCP could be directly dechlorinated and hydroxylated to hydroxyhydroquinone (HHQ), and then HHQ were further decomposed to small molecule acids. (5) By comparison of Sb(III) and Sb(V) sequestration on biogenic manganese oxides, it could be conclude as follows. Varied concentrations of Sb(III) was quickly oxidized within 10 min in the presence of biogenic Mn oxides, while Sb(V) sequestration on biogenic Mn oxides was completely inhibited. X-ray photoelectron spectrometer analysis revealed that Sb(V) was the dominant species in the solid phase after the reaction of Sb(III) with biogenic Mn oxides. Chemical extraction experiments showed that Sb(V) was mainly as Mn oxides bound and more stable fraction. X-ray diffraction results suggested that the oxidation of Sb(III) by biogenic Mn oxides led to the formation of manganese antimonate mineral (Mn2Sb2O7). Morevoer, bacterial activity in biogenic Mn oxides showed an apparent sequestration effect on Sb(III), but not on Sb(V). (6) By comparison of Sb and As removal efficiencies on quartz sand load biogenic manganese oxides and biochar, it could be conclude as follows. Quartz sand load biogenic manganese oxides column can transform Sb(III) and As(III) to Sb(V) and As(V), and reduce the toxicity of antimony and arsenic. Meanwhile, biogenic Mn oxides exhited a higher sequestration rate to antimony and arsenic at the early stage. The removal efficiency of As by biochar column increased with reaction time, but not effective for Sb removal. Overall, the removal efficiency of As using quartz sand load biogenic manganese oxides and biochar column was higher than Sb, and the two phases reactors have better removal effect to As over the period of the experiments.
学科领域生态学
语种中文
文献类型学位论文
条目标识符http://ir.xjlas.org/handle/365004/14609
专题研究系统_荒漠环境研究室
作者单位中科院新疆生态与地理研究所
推荐引用方式
GB/T 7714
王华伟. 应用锰氧化菌修复环境中砷、锑和有机复合污染物应用锰氧化菌修复环境中砷、锑和有机复合污染物[D]. 北京. 中国科学院大学,2015.
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