反硝化除磷技术的理论、工艺及影响因素的研究进展

废水的反硝化除磷技术作为生物除磷的一个新思路,因其能够解决传统脱氮除磷工艺运行中碳源不足、菌群竞争、泥龄难以控制等诸多问题,已成为废水生物处理研究的一个重要方向。概括反硝化处理的基本理论与优点,阐述A2／O、A2N工艺中实现反硝化除磷的控制方法及研究应甩情况,重点讨论C／N比、缺氧泡NO2负荷及污泥回流比对反硝化除磷效果的影响。     

双污泥反硝化脱氮除磷工艺的影响因素及分析

介绍了双污泥反硝化脱氮除磷工艺的反应机理,从C/N、超越污泥回流比、pH、DO、HRT及MLSS等方面分析了对双污泥反硝化脱氮除磷工艺在运行过程中的影响及目前国内外双污泥反硝化脱氮除磷工艺的研究现状,提出了今后在双污泥反硝化脱氮除磷工艺的研究中应当解决的问题.     

A2/O工艺的改进

自20世纪70年代以来逐渐成为废水脱氮除磷主流工艺的A2/O工艺,因其构成复杂,受污泥龄、碳源、硝酸盐等因素的影响,造成脱氮与除磷的功能之间相互制约。而在A2/O工艺的基础上改良与优化的PASF、UCT和VIP等技术,克服了A2/O工艺部分固有缺陷,优化和提高了其处理能力。此外,随着废水脱氮除磷理论的深化研究,同步反硝化除磷、短程硝化/反硝化、厌氧氨氧化技术和同步硝化与反硝化等新技术也取得了较大进展,这些新理论与新技术为A2/O工艺高效、低耗和安全稳定的运行奠定了坚实基础。     

低溶解氧对改良A／A／O工艺脱氮除磷的影晌

以采用厌氧／缺氧／好氧（A／A／O）工艺的城镇污水处理厂为研究对象,利用改良A／A／O中试装置开展处理实际污水的研究,通过与实际工艺的运行效果对比,系统探讨了低溶解氧（DO）浓度以及好氧池末端非曝气区的设置对脱氮除磷的影响。结果表明当好氧区的DO平均浓度从2．2mg／L逐渐降至1．0mg／L时,系统COD的去除效率与硝化效果未受到影响,但除磷效果明显下降;随着DO平均浓度的降低以及非曝气区对DO的缓冲,保证了缺氧区的缺氧环境,同时有效降低了内回流液中DO浓度的携带对碳源的消耗,提高了反硝化效率,使得系统对TN的去除率逐渐升高。就总体运行情况来看,A／A／O工艺中好氧区DO的平均浓度可以在1．0—2．0mg／L之间运行,同时在好氧区末端设置非曝气区,可以有效地缓冲内回流液中DO浓度对反硝化的影响,提高脱氮效率。     

倒置A2/O与改良A2/O工艺生产性试验比较

以典型高浓度城市污水为处理对象,在生产性试验规模上,比较了不同回流比条件下倒置A2/O工艺与改良A2/O工艺在脱氮除磷效果上的不同,并研究了通过缩短初沉池水力停留时间缓解脱氮除磷碳源矛盾的可行性.试验结果表明,以较低污泥回流比运行的倒置A2/O工艺可以保持较好脱氮除磷效果,与相同污泥回流比而硝化液回流比为300%平行运行的改良A2/O工艺脱氮效果基本相当,但除磷效果优于改良A2/O工艺;提高倒置A2/O工艺污泥回流比至200%左右时,其脱氮除磷效果均优于改良A2/O工艺;通过缩短初沉池水力停留时间可以有效缓解生物脱氮除磷碳源的矛盾,提高系统整体脱氮除磷效果.     

改良型倒置A~2/O生物膜工艺的脱氮除磷性能研究

通过在倒置A2/O工艺中增设填料,并对其污泥及硝化液回流方式进行变化后,得到兼具脱氮除磷功能与生物膜特点的改良型倒置A2/O生物膜工艺,并以实际生活污水为处理对象考察了工艺的脱氮除磷性能。结果表明,系统采用硝化液回流与污泥回流分离的方式,并增设组合填料与火山岩后,有助于提升系统的脱氮除磷性能,增强系统的稳定性。当DO质量浓度维持在2.0 mg/L和硝化液体积回流比为200%的条件下,系统对COD、NH4+-N、TN及TP的去除率分别可达84.9%、92.8%、70.9%和75.3%。DO质量浓度及硝化液回流比对系统的脱氮除磷性能有较大影响。     

A~2/O工艺强化反硝化除磷控制策略研究

在传统A2/O工艺的基础上,通过设立预缺氧区(即建立A-A2/O工艺)、外加碳源等手段,强化A2/O工艺处理低C/N生活污水的脱氮除磷能力。试验结果表明,经过强化后的A2/O反应器对COD、TN及TP去除效果良好,COD、TN及TP的去除率分别为92%、98%、85%。系统表现出明显的反硝化除磷现象,缺氧区除磷量占总除磷量的17.18%。反硝化除磷现象的产生降低了碳源缺乏对A2/O工艺脱氮除磷性能的影响,提高碳源的利用效率。为采用A2/O工艺处理低C/N生活污水的污水处理厂提供理论依据。     

连续流中亚硝化反硝化除磷同步发生的调控因子

为实现连续流内亚硝化与以亚硝酸盐氮为电子受体的反硝化除磷生化过程的同步发生,解决低碳城市污水高效节能脱氮除磷的问题,实验构建了厌氧/限氧(A/OLA)连续流工艺。结果表明,控制DO的质量浓度在0.3~1.0 mg/L时,水力停留时间(HRT)对脱氮效果没有显著影响,但会影响厌氧区反硝化除磷菌(DNPAOs)的积累PHB,导致除磷效果下降。当污泥回流比(R)为1.4和1.2时,会稀释厌氧区内各物质的含量,造成亚硝化与反硝化除磷两生化反应的失衡,从而影响同步脱氮除磷效果;当R为0.8和1.0时,二沉池会发生不同程度的二次释磷,影响除磷效果。由此可知,HTR为14 h、R为1.0时,A/OLA连续流工艺同步脱氮除磷效果为佳,TP、TN的平均去除率分别为97.52%、97.76%。     

新型生物脱氮工艺中N_2O产生及释放研究进展

N_2O是重要的温室气体之一,微生物作用是大气中N_2O的主要产生源.大量污水脱氮工艺的研究及应用表明,生物脱氮过程中N_2O主要产生于微生物的硝化和反硝化代谢过程.近年来,许多新型生物脱氮工艺已逐步应用到实际污水处理中.本文阐述了硝化、反硝化阶段N_2O的产生机理,并分析了传统生物脱氮工艺及同步硝化反硝化、 短程硝化-反硝化、厌氧氨氧化、反硝化除磷等新型工艺中N_2O的产生量及其影响因素,提出在追求高脱氮效率的同时,优化系统运行条件及种群结构,可在一定程度上降低系统N_2O的产量及危害,为新型生物脱氮工艺实际运行过程中降低N_2O的产量提供参考.     

A+A~2/O工艺脱氮除磷参数调控及运行效果分析

结合广州市猎德污水处理厂A+A2/O工艺的实际运行情况,对其脱氮除磷参数调控和运行效果进行了分析。首先考察了冬天低温条件下的脱氮除磷效果,然后经过不同混合液体积回流比和污泥体积回流比的运行分析,得到适合工艺运行的最佳值,分别为100%和100%,还对其它参数调控进行了简要介绍,最后对工艺整体运行效果进行了分析,得到良好的结果。证明A+A2/O工艺具有良好的脱氮除磷效果。     

Many Drugs of Abuse May Be Acutely Transformed to Dopamine,Norepinephrine and Epinephrine In Vivo

It is well established that a wide range of drugs of abuse acutely boost the signaling of the sympathetic nervous system and the hypothalamic–pituitary–adrenal (HPA) axis, where norepinephrine and epinephrine are major output molecules. This stimulatory effect is accompanied by such symptoms as elevated heart rate and blood pressure, more rapid breathing, increased body temperature and sweating, and pupillary dilation, as well as the intoxicating or euphoric subjective properties of the drug. While many drugs of abuse are thought to achieve their intoxicating effects by modulating the monoaminergic neurotransmitter systems (i.e., serotonin, norepinephrine, dopamine) by binding to these receptors or otherwise affecting their synaptic signaling, this paper puts forth the hypothesis that many of these drugs are actually acutely converted to catecholamines (dopamine, norepinephrine, epinephrine) in vivo, in addition to transformation to their known metabolites. In this manner, a range of stimulants, opioids, and psychedelics (as well as alcohol) may partially achieve their intoxicating properties, as well as side effects, due to this putative transformation to catecholamines. If this hypothesis is correct, it would alter our understanding of the basic biosynthetic pathways for generating these important signaling molecules, while also modifying our view of the neural substrates underlying substance abuse and dependence, including psychological stress-induced relapse. Importantly, there is a direct way to test the overarching hypothesis: administer (either centrally or peripherally) stable isotope versions of these drugs to model organisms such as rodents (or even to humans) and then use liquid chromatography-mass spectrometry to determine if the labeled drug is converted to labeled catecholamines in brain, blood plasma, or urine samples.     

Sapindaceae,cyanolipids, and bugs

Scentless plant bugs (Heteroptera: Rhopalidae) are so named because adults of the Serinethinae have vestigial metathoracic scent glands. Serinethines are seed predators of Sapindales, especially Sapindaceae that produce toxic cyanolipids. In two serinethine species whose ranges extend into the southern United States,Jadera haematoloma andJ. sanguinolenta, sequestration of host cyanolipids as glucosides renders these gregarious, aposematic insects unpalatable to a variety of predators. The blood glucoside profile and cyanogenesis ofJadera varies depending on the cyanolipid chemistry of hosts, and adults and larvae fed golden rain tree seeds (Koelreuteria paniculata) excrete the volatile lactone, 4-methyl-2(5H)-furanone, to which they are attracted.Jadera fed balloon vine seeds (Cardiospermum spp.) do not excrete the attractive lactone. Loss of the usual heteropteran defensive glands in serinethines may have coevolved with host specificity on toxic plants, and the orientation ofJadera to a volatile excretory product could be an adaptive response to save time.Mention of a commercial product does not consititute an endorsement by the USDA.     

Insect antifeedant properties of anthranoids from the genusVismia

Vismiones and ferruginins, representatives of a new class of lypophilic anthranoids from the genusVismia were found to inhibit feeding in larvae of species ofSpodoptera, Heliothis, and inLocusta migratoria.     

Direct observation of freeze-thaw instability of latex coatings via high pressure freezing and cryogenic SEM

Despite its industrial importance, the subject of freeze-thaw (F/T) stability of latex coatings has not been studied extensively. There is also a lack of fundamental understanding about the process and the mechanisms through which a coating becomes destabilized. High pressure (2100 bar) freezing fixes the state of water-suspended particles of polymer binder and inorganic pigments without the growth of ice crystals during freezing that produce artifacts in direct imaging scanning electron microscopy (SEM) of fracture surfaces of frozen coatings. We show that by incorporating copolymerizable functional monomers, it is possible to achieve F/T stability in polymer latexes and in low-VOC paints, as judged by the microstructures revealed by the cryogenic SEM technique. Particle coalescence as well as pigment segregation in F/T unstable systems are visualized. In order to achieve F/T stability in paints, latex particles must not flocculate and should provide protection to inorganic pigment and extender particles. Because of the unique capabilities of the cryogenic SEM, we are able to separate the effects of freezing and thawing, and study the influence of the rate of freezing and thawing on F/T stability. Destabilization can be caused by either freezing or thawing. A slow freezing process is more detrimental to F/T stability than a fast freezing process; the latter actually preserves suspension stability during freezing. Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, October 27–29, 2004 in Chicago, IL. Tied for first place in The John A. Gordon Best Paper Competition.     

2008～2009年世界塑料工业进展

收集了2008年7月～2009年6月世界塑料工业的相关资料,介绍了2008～2009年国外塑料工业的发展情况,提供了世界塑料产量、消费量及全球各类树脂的需求量及产能情况。按通用热塑性树脂(聚乙烯、聚丙烯、聚苯乙烯、聚氯乙烯、ABS树脂)、工程塑料(尼龙、聚碳酸酯、聚甲醛、热塑性聚酯、聚苯醚)、特种工程塑料(聚苯硫醚、液晶聚合物、聚醚醚酮)、通用热固性树脂(酚醛、聚氨酯、环氧树脂、不饱和聚酯树脂)不同品种的顺序,对树脂的产量、消费量、供需状况及合成工艺、产品应用开发、树脂品种的延伸及应用的进一步扩展等技术作了详细介绍。     

Ethanol and (−)-α-Pinene: Attractant Kairomones for Bark and Ambrosia Beetles in the Southeastern US

In 2002–2004, we examined the flight responses of 49 species of native and exotic bark and ambrosia beetles (Coleoptera: Scolytidae and Platypodidae) to traps baited with ethanol and/or (−)-α-pinene in the southeastern US. Eight field trials were conducted in mature pine stands in Alabama, Florida, Georgia, North Carolina, and South Carolina. Funnel traps baited with ethanol lures (release rate, about 0.6 g/day at 25–28°C) were attractive to ten species of ambrosia beetles (Ambrosiodmus tachygraphus, Anisandrus sayi, Dryoxylon onoharaensum, Monarthrum mali, Xyleborinus saxesenii, Xyleborus affinis, Xyleborus ferrugineus, Xylosandrus compactus, Xylosandrus crassiusculus, and Xylosandrus germanus) and two species of bark beetles (Cryptocarenus heveae and Hypothenemus sp.). Traps baited with (−)-α-pinene lures (release rate, 2–6 g/day at 25–28°C) were attractive to five bark beetle species (Dendroctonus terebrans, Hylastes porculus, Hylastes salebrosus, Hylastes tenuis, and Ips grandicollis) and one platypodid ambrosia beetle species (Myoplatypus flavicornis). Ethanol enhanced responses of some species (Xyleborus pubescens, H. porculus, H. salebrosus, H. tenuis, and Pityophthorus cariniceps) to traps baited with (−)-α-pinene in some locations. (−)-α-Pinene interrupted the response of some ambrosia beetle species to traps baited with ethanol, but only the response of D. onoharaensum was interrupted consistently at most locations. Of 23 species of ambrosia beetles captured in our field trials, nine were exotic and accounted for 70–97% of total catches of ambrosia beetles. Our results provide support for the continued use of separate traps baited with ethanol alone and ethanol with (−)-α-pinene to detect and monitor common bark and ambrosia beetles from the southeastern region of the US.     

ICP-MS法测定地球化学样品中As、Cr、Ge、V等18种微量痕量元素的研究

建立了测定地球化学样品中包括As、Cr、Ge、V等18种微量、痕量元素的ICP-MS方法。地化试样用HF-HNO3混酸分解后,以1 1 HNO3溶解干渣。由于制样不使用盐酸,避免了Cl对As、Cr、Ge、V的质谱干扰。用国家一级地球化学标准物质GBW 07309制备溶液优化仪器工作参数,并用于校准。方法测定限(6s)为:0.007~6.4μg/g,精密度(RSD%,n=12)为:29%~9.4%,经过国家一级地球化学标准物质的分析验证,结果与标准值吻合。方法已应用于国土资源调查的试样分析。