厌氧/好氧/缺氧模式运行SBR工艺的影响因素

采用厌氧/好氧/缺氧模式运行的SBR工艺处理人工配水模拟生活污水,分析了泥龄、温度、曝气量对反硝化除磷过程的影响。结果表明:温度为30℃、SRT为25 d、曝气量在64 L/h时,发生明显的反硝化除磷现象,缺氧段吸磷速率可达到0.054 0 mg/(g·h)。     

进水方式及水质对厌氧/缺氧系统反硝化聚磷的影响研究

采用厌氧/缺氧(A/A)SBR和人工废水,研究了不同硝酸盐投加方式下反硝化除磷的效果,探讨了进水方式以及水质对反硝化除磷的影响.结果表明,在厌氧段进水,反应器内初期形成的较高浓度磷会对聚磷菌释磷及其吸收碳源产生抑制作用.控制投加的COD量,使反应器内在厌氧段存在充足的碳源而在缺氧段时基本不残留碳源,则有利于提高除磷效果.厌氧/缺氧交替的环境,若厌氧段初始进水后反应器内初期磷浓度较高则有利于反硝化而非反硝化聚磷.     

A/O/ASBR同步脱氮除磷实验研究

采用人工配水,通过控制进水p H值为7.5~8.2、DO为0.4~0.7 mg/L、污泥龄9~13天等实验条件,经过两个阶段共46d的驯化培养,在厌氧/好氧/缺氧(A/O/A)SBR反应器内实现短程同步硝化反硝化与除磷过程的耦合。系统稳定运行后,对一个典型周期内水质的变化情况进行了测定和分析,系统对COD、NH+4-N、TN、TP的去除率分别为94.8%、97.6%、89.4%、93.1%。在此基础上,探讨了不同进水p H、不同曝气量对系统运行稳定性的影响。结果表明:随着p H的改变,系统对去除氮、磷的稳定性呈现不同的变化趋势;而过高的曝气量,会造成系统内的短程硝化向全程硝化转变。     

人工配水和实际污水(AO)2SBR同步脱氮除磷比较研究

在污泥停留时间为15d、HRT为1.5h和DO的质量浓度约为2.5 mg·L-1条件下,分别对人工配水和实际生活污水进行了(AO)2SBR法同步脱氮除磷试验,并对处理效果进行了对比.结果表明,人工配水和实际污水的(AO)2SBR工艺好氧和缺氧脱氮除磷过程几乎全部以厌氧阶段合成的胞内聚羟基烷酸为碳源,说明反硝化脱氮除磷确实可实现“一碳两用”;人工配水和实际污水的好氧吸磷率分别为67.49％和93.42％、缺氧除氮率分别为58.22％和77.98％,实际污水驯化得到的反硝化聚磷菌和聚磷菌具有更强的反硝化能力和好氧吸磷能力.     

亚硝氮为电子受体缺氧吸磷的试验研究

为进一步了解反硝化除磷菌,以SBR反应器在厌氧/好氧条件下培养的聚磷菌为对象,进行批次试验,研究了不同浓度NO_(2-)~--N对缺氧吸磷过程的影响。结果证实:NO_(2-)~--N可以作为缺氧吸磷的电子受体,但吸磷速率比好氧吸磷低,吸磷量比好氧吸磷少。反应开始时的NO_(2-)~--N/P对反应过程影响很大,该试验中NO_(2-)~--N/P为0.60时缺氧吸磷量和吸磷速率均达到最高。低于该值时,吸磷量和吸磷速率随着氮磷比的提高而增加,NO_(2-)~--N消耗完时,体系出现"二次释磷"现象;高于该值时,吸磷量和吸磷速率随着氮磷比的提高而减少。NO_(2-)~--N浓度达到80mg/L时,没有发现对反应的抑制作用。     

反硝化聚磷菌的培养富集及处理生活污水的稳定运行

在厌氧-好氧交替运行的序批式反应器(sequencing batch reactor, SBR)中,以C/P比大于50的实际生活污水为进水,成功驯化富集聚磷菌,平均厌氧释磷量为15 mg·L~(-1),出水PO_4~(3-)-P浓度稳定小于0.5 mg·L~(-1)。在系统运行的第74 d调整运行模式为厌氧-缺氧-好氧,在缺氧开始时短期投加NO_3~--N配水以驯化培养反硝化聚磷菌。保持系统内NO_3~--N浓度不变,在进水COD浓度为250 mg·L~(-1)时,反硝化除磷效果最佳,平均反硝化除磷量占除磷量的比为87.1%。不同pH下反硝化除磷速率的小试证明,在pH=7.0时得到最大的比吸磷速率2.1 mg P·(g VSS·h)~(-1)。此时调整NO_3~--N进水为另一个全程硝化反应器的出水,并加大排水比增加缺氧初的进水量使得反应器内缺氧时的pH接近7.0,与未改变pH时对比表明前者在缺氧段反硝化除磷速率加快。反应器共运行160 d,稳定完成COD的去除与反硝化除磷过程。     

序批式活性污泥法反硝化聚磷菌的培养驯化研究

以某污水处理厂活性污泥作为种泥,采用序批式活性污泥法(SBR)进行反硝化聚磷菌(DPB)培养驯化研究。结果表明,经过厌氧-好氧,厌氧-换水-缺氧,厌氧-缺氧,厌氧-缺氧-短时曝气4个阶段培养驯化,系统出水效果良好:出水PO43--P的质量浓度稳定在0.5 mg.L-1以下,平均除磷率达96%;出水COD稳定在50 mg.L-1以下,平均去除率达77%。DPB占聚磷菌的比例约为65.02%。当投加不同含量的NO3--N时,硝酸盐的含量只影响吸磷速率而不影响吸磷量。当缺氧段DPB体内的PHB为限制因素时,缺氧吸磷过程在不同NO3--N含量下基本相同。     

序批式反应器中反硝化除磷脱氮的研究

为了提高污水脱氮除磷的效率,研究采用序批式反应器(SBR工艺)厌氧、好氧和缺氧(AOA)的运行方式富集反硝化聚磷菌(DPB),实现同步脱氮除磷。结果表明:在好氧段投加甲醇作为碳源(25—40 mg/L)可有效抑制好氧吸磷,对硝化反应影响较小,能够在缺氧段实现同时反硝化脱氮除磷。SBR反应器稳定运行10个月,当进水NH4+-N、PO43--P分别为30,15 mg/L时,总氮(TN)和PO43--P的平均去除率分别为82.5%和92.1%。聚磷菌能够利用硝酸盐作为电子受体,DPB占总聚磷菌的比例达到44.8%。与A2O运行方式相比,AOA运行方式更有利于实现DPB的富集。     

不同曝气方式下亚硝化反应器的启动及N2O释放

在常温下〔(20±1)℃〕利用SBR反应器处理低碳氮比实际生活污水,考察连续曝气和间歇曝气方式下亚硝化过程的启动及N_2O的释放。控制SBR反应器DO处于较低水平,并在pH"氨谷"点出现时停止曝气。结果表明,连续曝气和间歇曝气方式分别运行100、75 d后均实现了亚硝化过程。间歇曝气方式下更易实现亚硝化过程。连续曝气和间歇曝气模式下的N_2O转化率分别为12.2%、8.10%。AOB的好氧反硝化过程是N_2O释放的主要途径。间歇曝气模式下的缺氧阶段能够减少好氧段NO_2~-积累,降低好氧反硝化过程底物浓度,减少N_2O释放。     

交替式厌/缺氧-好氧双膜反硝化除磷工艺

采用某污水处理厂A²/O工艺中的活性污泥为种泥,以模拟生活污水为对象,考察了交替式厌/缺氧-好氧双膜反硝化除磷工艺的启动与运行特性,并采用高通量测试技术分析系统除磷污泥的菌群结构。通过60天的启动试验,系统内反硝化聚磷菌占聚磷菌总数的比例由21.3%提高到94.4%,出水磷在0.6mg/L左右。通过逐步增加进水氨氮的方法运行2个月,系统的脱氮除磷效果稳定。在进水P浓度为6.4mg/L,保持进水N/P比为8.8,交替厌/缺氧-好氧双膜反硝化除磷工艺效能最优,可达0.12kgN/(m³?d)和0.018kgP/(m³?d),出水总磷(TP)0.8mg/L,总氮(TN)12mg/L,出水COD、NH₃-N和TN达到国家综合排放标准GB18918-2002一级A排放标准。周期试验中,pH值、氧化还原电位(oxidation-reduction potential,ORP值)均可作为厌氧释磷的控制参数,ORP也可指示缺氧吸磷的终点。典型周期内硝酸盐、亚硝酸盐的消耗量与磷的吸收量基本呈线性关系。系统内污泥多样性约为种泥的0.5倍,在“门”、“属”分类级别上分别以Proteobacteria、Xanthomonadales-nobank为主。     

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.     

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.     

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.     

Novel polyurethane coating technology through glycidyl carbamate chemistry

Glycidyl carbamate chemistry combines the excellent properties of polyurethanes with the crosslinking chemistry of epoxy resins. Glycidyl carbamate functional oligomers were synthesized by the reaction of polyfunctional isocyanate oligomers and glycidol. The oligomers were formulated into coatings with several amine functional crosslinkers at varying stoichiometric ratios and cured at different temperatures. Properties such as solvent resistance, hardness, and impact resistance were dependent on the composition and cure conditions. Most coatings had an excellent combination of properties. Studies were carried out to determine the kinetics of the curing reaction of the glycidyl carbamate functional oligomers with multifunctional and model amines. Detailed kinetic analysis of the curing reactions was also undertaken. The results indicated that the glycidyl carbamate functional group is more reactive than a glycidyl ether group. Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, on October 27–29, 2004, in Chicago, IL.