厌氧氨氧化的生态因子研究进展

厌氧氨氧化生物脱氮技术是近年来发展起来的新型的生物脱氮技术,其实质是氨的亚硝化与亚硝化产物以氨为电子供体的还原相偶联.从生态因子的角度出发,综述了厌氧氨氧化的影响因子(生物因子及非生物因子)的研究进展.并对厌氧氨氧化的应用前景进行了展望,提出了其今后的研究方向.     

硫酸盐型厌氧氨氧化性能的研究

研究了自养条件下硫酸盐型厌氧氨氧化的性能．试验表明,在无氧条件下,SO4^2-和NH4^＋化学性质稳定,两者间不发生化学反应．在厌氧反应器中接种厌氧消化污泥,经过三年多的连续驯化,可使厌氧反应器发生硫酸盐型厌氧氨氧化（NH4^＋-N和SO4^2-S同时减少）．在高基质浓度下,NH4＋-N和5042-浓度平均降低71．67和56．82mg．L^-1．硫酸盐型厌氧氨氧化的标准吉布斯自由能变化较小,反应可以发生,但不易进行．高基质浓度和低氧化还原电位对该反应有促进作用．     

有机物对厌氧氨氧化菌活性影响研究进展

厌氧氨氧化反应(Anammax)功能菌世代时间长,生长条件苛刻,在有机物存在的条件下,反应过程和脱氮效果极易受到影响。因此,如何降低有机物对厌氧氨氧化菌(AAOB)活性的影响,是其应用的难点。近年来,研究者在有机物对Anammox反应影响方面开展了大量研究,本文主要综述了有机物的浓度和种类对AAOB活性的影响,并建议控制低浓度有机物环境下(100~200 mg/L以下),可降低有机物对AAOB活性的抑制;同时,可调控不同种类和浓度有机物的异位利用,形成Anammox-反硝化协同作用、Anammox-甲烷化-反硝化耦合作用等实现同步脱碳除氮。最后认为,在有机物对Anammox的影响方面,还可进一步开展AAOB的新陈代谢机制、与其他菌种的竞争合作机理以及耦合作用下菌种富集纯化等方面的研究。     

纳米TiO2薄膜耦合光催化氧化还原反应脱除水中无机氮

由溶胶-凝胶法制备了固定化二氧化钛薄膜,研究了薄膜催化剂光催化脱除含氨氮-亚硝酸氮混合液中无机氮的活性.考察了溶胶制备工艺、催化反应条件(尤其pH)对光催化活性的影响.实验证明:酸性条件有利于亚硝酸氮的还原,碱性条件有利于氨氮的氧化,通过调节pH可以获得光催化氧化氨氮和还原亚硝酸氮耦合效果.如果加入甲酸维持酸性务件,反应0.5 h后再将pH调回碱性,可以大大提高光催化脱氮的效果:经过2 h的光催化反应,二氧化钛膜催化总氮去除率可达50%以上.经多次试验证明附载二氧化钛薄膜不脱落,光催化活性未见减弱,可重复利用.提出了光催化脱氮的反应机理.     

微生物群落对多氯酚的脱氯特性及机理研究

从正在运行的流化床生物反应器中分离出对三氯酚具有高效脱氯能力的微生物群落. 在含柠檬酸钛为氧化还原缓冲剂的合成培养基中研究了该群落的生理特性. 结果表明, 该微生物菌群可以利用丙酮酸为碳源和能源, 丙酮酸发酵、硫酸盐还原和脱氯反应三个过程严格地按顺序依次进行, 并且丙酮酸浓度在最初2 d内急剧下降, 同时有代谢产物乙酸、甲酸和氢气形成. 只有当硫酸盐被还原成硫化物后, 脱氯反应才会发生. 硫酸盐和钼酸盐的存在会强烈地抑制微生物的脱氯活性. 溴乙烷磺酸酯(BES)可以完全抑制微生物的产甲烷活性. 青霉素G(10 μg/mL)对该微生物菌群的脱氯作用没有抑制. 该微生物菌群按形态特征可以分为3类, 即弧菌、链球菌和杆菌. 利用荧光标记的16S和23S rRNA寡核苷酸探针进行原位杂交试验表明, 该微生物菌群中存在Proteobacteria的r亚类和δ亚类.     

高效液相色谱法研究H_2O_2氧化Na_2S_2O_3的反应动力学

建立了反相离子对高效液相色谱法对H2O2-Na2S2O3反应体系的反应物和中间产物进行了分离检测方法,并对此反应体系在酸性条件下的氧化反应动力学做了研究.结果表明:在25℃,pH 4.76时硫代硫酸盐氧化过程中出现的产物有:亚硫酸盐、连三硫酸盐、连四硫酸盐、连五硫酸盐、连六硫酸盐、连七硫酸盐和硫酸根,pH越低越易生成更高的连多硫酸盐;在氧化H2O2过量的情况下反应对硫代硫酸盐来说为一级反应,并测得了准一级反应速率常数.     

流光放电等离子体液相氧化亚硫酸铵

在氨-硫铵法烟气脱硫中, 一个关键环节是将副产物的四价硫S(IV)氧化为六价硫S(VI). 采用可规模化的流光放电液相氧化技术, 通过交直流叠加(AC/DC)电源, 激发气体放电产生等离子体对氨法脱硫高浓度的亚硫酸铵进行氧化. 实验测量了该氧化过程与溶液浓度、放电功率密度、溶液pH值、温度以及传质效率因子等各种参数的关系. 研究表明, 在亚硫酸铵摩尔浓度为3 mol·L-1时, 可以获得有实用价值的反应速率, 摩尔能耗减低到50 Wh·mol-1以下, 显示出很好的应用前景.     

氮氧自由基研究 ⅩⅪ.水溶液中哌啶氮氧自由基单电子还原反应机理的极谱研究

氮氧自由基在电极上可得到电子而被还原,但关于哌啶氮氧自由基在水溶液中的电极还原反应,仅Neiman等用经典极谱法考察过其半波还原电位与介质pH的关系,认为自由基被还原为相应羟胺,质子参与电极反应,但未能确定质子化过程是先于还是后于电子转移过程。氮氧自由基在水溶液中可氧化谷胱甘肽、半胱氨酸,反应产物分布强烈受介质pH影响。氮氧自由基氧化维生素C的速率随介质pH改变而变化。已经证明,这些反应均经过单电子转移氧化还原反应机理,氮氧自由基均被还原为羟胺。因此,用电化学方法研究质子在氮氧自由基单电子还原过程中的作用,对于进一步阐明氮氧自由基与上述生物分子的电子转移反应机理无疑有一定实际意义。     

短程硝化-厌氧氨氧化工艺的挑战与对策

短程硝化-厌氧氨氧化（PN/A）工艺与传统生物脱氮工艺相比，具有能耗低、设备简单、污泥产率低等诸多优点，在污水脱氮领域备受关注。本文首先总结了PN/A工艺在实际应用中存在的一些挑战，比如，处理高C/N废水效果不佳、亚硝酸盐氧化细菌（NOB）抑制困难、启动缓慢等。然后，针对上述挑战，提出了一些PN/A工艺的改进措施。可使用多种预处理技术来降低废水有机物含量，以减弱高C/N比废水的负面影响；根据NOB、厌氧氨氧化菌（AnAOB）、氨氧化细菌（AOB）之间生长条件的差异，通过调控温度、pH、溶解氧等环境条件或添加抑制剂来抑制NOB的生长。接着，总结了PN/A工艺快速启动的方法，即通过添加化学物质、物理场、外加AnAOB种泥，并给予AnAOB最佳生长条件等方法，实现PN/A工艺的快速启动。最后，展望了PN/A工艺未来有待深入研究的方向。     

煤非催化加氢热解过程中脱硫脱氮效应及硫变迁特性

采用５ｇ固定床反应器和在线热解质谱，对煤加氢热解过程的脱硫脱氮效应及硫变迁特性进行了考察。结果表明，煤中几乎所有硫铁硫矿被脱除殆尽，半焦中残存的向亘硫主要表现为硫酸盐硫。而热解过程中硫往焦油产组分的变迁、转移主要取准地煤中噻吩类含硫化物的不完全氢化还原反应，而与煤中其它有机硫化珠的含量关系不大，从而使高噻吩煤难于获得低硫充洁净焦油产物。同时发现，由于氢传质扩散的相对滞后，微量硫与煤中内在氧发生氧化     

Isolation and identification of bacteria responsible for simultaneous anaerobic ammonium and sulfate removal

Sulfate-dependent anaerobic ammonium oxidation is a novel biological reaction,in which ammonium is oxidized with sulfate as the electron acceptor under anoxic conditions.Ammonium and sulfate are cosmopolitan chemical species which are an integral part of the global nitrogen and sulfur cycles.A detailed exploration of sulfate-dependent anaerobic ammonium oxidation is quite practical.In this work,a bacterial strain named ASR has been isolated from an anaerobic ammonia and sulfate removing reactor working unde...     

Performance of sulfate-dependent anaerobic ammonium oxidation

The performance of sulfate-dependent anaerobic ammonium oxidation was studied. The results showed that both SO₄ ²⁻ and NH₄ ⁺ were chemically stable under anaerobic conditions. They did not react with each other in the absence of biological catalyst (sludge). The anaerobic digested sludge cultivated in an anaerobic reactor for three years took on the ability of oxidizing ammonium with sulfate anaerobically. The average reduction of sulfate and ammonium was 71.67 mg·L⁻¹ and 56.82 mg·L⁻¹ at high concentrations. The reaction between SO₄ ²⁻ and NH₄ ⁺ was difficult, though feasible, due to its low standard Gibbs free energy change. The experiment demonstrated that high substrate concentrations and low oxidation-reduction potential (ORP) may be favourable for the biological reaction. Supported by the National Natural Science Foundation of China (Grant No. 30770039) and the High-tech Research and Development Program of China (Grant No. 2006AA06Z332)     

Emulsion Polymerization Pathway for Preparation of Polyaniline‐Sulfate Salt,using Non Ionic Surfactant

In this work, aniline was polymerized directly to the polyaniline‐sulfate salt without using a protonic acid. The polyaniline‐sulfate salt was prepared by emulsion polymerization, using a non ionic surfactant such as poly(ethylene glycol)–block poly(propylene glycol)‐block poly(ethylene glycol). In the aniline oxidation process, to give the polyaniline salt by ammonium persulfate, the sulfate ion is generated from ammonium persulfate and doped on to the polyaniline. Ammonium persulfate acts both as an oxidizing agent, as well as the protonating agent in the aniline polymerization process, to give the polyaniline salt. This result indicates that the effect of sulfate ion, generated by ammonium persulfate during oxidation of aniline to the polyaniline salt, may be taken into consideration in the polymerization process of aniline.     

Preparation of polyaniline‐sulfate salt ­by emulsion and aqueous ­polymerization pathway without using ­protonic acid

Aniline was polymerized directly into polyaniline‐sulfate salt without using protonic acid in this work. Polyaniline‐sulfate salt was prepared by emulsion and aqueous polymerization pathways. The dopant i.e. sulfate ion in polyaniline‐sulfate salt was generated from ammonium persulfate which was used for oxidizing aniline. Ammonium persulfate acts both as oxidizing agent as well as protonating agent in the polymerization process of aniline to polyaniline salt. The efficiency of oxidizing and protonating power of ammonium persulfate is increased by the use of surfactant. The activity of ammonium persulfate is further increased by the use of sulfuric acid as protonic acid. It may be necessary to consider the effect of sulfate ion which is generated during the oxidation process of aniline in the chemical polymerization of aniline to polyaniline salt by ammonium persulfate either aqueous or emulsion polymerization pathway in the presence of protonic acid/functionalized protonic acid. Copyright © 2001 John Wiley & Sons, Ltd.     

Crystallization of aqueous ammonium sulfate particles internally mixed with soot and kaolinite: crystallization relative humidities and nucleation rates

Using optical microscopy, we investigated the crystallization of aqueous ammonium sulfate droplets containing soot and kaolinite, as well as the crystallization of aqueous ammonium sulfate droplets free of solid material. Our results show that soot did not influence the crystallization RH of aqueous ammonium sulfate particles under our experimental conditions. In contrast, kaolinite increased the crystallization RH of the aqueous ammonium sulfate droplets by approximately 10%. In addition, our results show that the crystallization RH of aqueous ammonium sulfate droplets free of solid material does not depend strongly on particle size. This is consistent with conclusions made previously in the literature, based on comparisons of results from different laboratories. From the crystallization results we determined the homogeneous nucleation rates of crystalline ammonium sulfate in aqueous ammonium sulfate droplets and the heterogeneous nucleation rates of crystalline ammonium sulfate in aqueous ammonium sulfate particles containing kaolinite. Using classical nucleation theory and our experimental data, we determined that the interfacial tension between an ammonium sulfate critical nucleus and an aqueous ammonium sulfate solution is 0.064 +/- 0.003 J m(-2) (in agreement with our previous measurements), and the contact angle between an ammonium sulfate critical nucleus and a kaolinite surface is 59 +/- 2 degrees. On the basis of our results, we argue that soot will not influence the crystallization RH of aqueous ammonium sulfate droplets in the atmosphere, but kaolinite can significantly modify the crystallization RH of atmospheric ammonium sulfate droplets. As an example, the CRH50 (the relative humidity at which 50% of the droplets crystallize) ranges from about 41 to 51% RH when the diameter of the kaolinite inclusion ranges from 0.1 to 5 microm. For comparison, the CRH50 of aqueous ammonium sulfate droplets (0.5 microm diameter) free of solid material is approximately 34.3% RH under atmospheric conditions.     

Cerium catalyzed persulfate oxidation of polycyclic aromatic hydrocarbons to quinones

A practical synthesis of polycyclic quinones from the parent hydrocarbons is described. The twophase oxidation of hydrocarbons was accomplished by using ammonium persulfate in the catalytic presence of cerium ammonium sulfate, silver nitrate, and sodium dodecyl sulfate. The reaction conditions and scope have been discussed in detail.     

Oxidation of cyclohexene with Ce (IV) salts

Conclusions Together with the main products, namely cyclohexen-2-ol and cyclohexen-2-one, the oxidation of cyclo-hexene with cerium ammonium nitrate or cerium ammonium sulfate gives cyclohexanol and cyclohexanone, which are probably formed by the cation-radical mechanism.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 7, pp. 1664–1666, July, 1977.     

Improved analysis of ladderane lipids in biomass and sediments using high-performance liquid chromatography/atmospheric pressure chemical ionization tandem mass spectrometry

Ladderane lipids, containing three or five linearly concatenated cyclobutane moieties, are considered to be unique biomarkers for the process of anaerobic ammonium oxidation, an important link in the oceanic nitrogen cycle. Due to the thermal lability of the strained cyclobutane moieties, the ladderane lipids are difficult to analyze by gas chromatography. A method combining high-performance liquid chromatography coupled to positive ion atmospheric pressure chemical ionization tandem mass spectrometry (HPLC/APCI-MS/MS) was developed for the analysis of the most abundant ladderane lipids, occurring as fatty acids and ether-bound to glycerol. Detection was achieved by selective reaction monitoring of four specific fragmentations per ladderane lipid. Detection limits of 30-35 pg injected on-column and a linear response (r(2) > 0.99) over nearly 3 orders of magnitude were achieved for all compounds. Using this method, these unique ladderane lipids were for the first time identified in a surface sediment from the Gullmarsfjorden, in concentrations ranging from 1.1-5.5 ng/g for the ladderane fatty acids and of 0.7 ng/g for the monoether. It is foreseen that this method will allow the investigation of the occurrence of anaerobic ammonium oxidation in natural settings in much greater detail than before.