不同回流比和SRT对A/O-MBR脱氮除磷的影响

通过改变回流比和污泥龄(SRT)考察其对A/O-MBR脱氮除磷效果的影响,结果表明:在整个运行过程中,不同回流比对氨氮的去除率都在96%以上。提高回流比,使得反硝化过程不能完全进行,从而导致出水NO3--N升高,脱氮效率降低。而SRT对NH4+-N、NO3--N和TN没有明显影响。此外,在SRT=30 d,回流比较低时(回流比为2),厌氧释磷作用较为明显,而提高回流比(回流比为3),反硝化聚磷过程得到强化,反应器均能达到较高的除磷效果(95%以上)。而当污泥中TP含量达到饱和时,增加SRT至60 d,并不能有效改善除磷效果。     

A/O生物脱氮回流液中溶解氧影响因素的研究

A／O工艺处理废水过程中，回流液中的溶解氧影响反硝化脱氮的速率。选择回流比为3，回流液的溶解氧小于3．0mg／L较为适宜。     

改良A^2／O工艺脱氮除磷研究

实验研究了污泥回流比和混合液回流比对改良A2/O工艺脱氮除磷的影响.预缺氧池能够让NO3--N在进入厌氧池前被完全反硝化,保证磷的正常释放.污泥回流比对整个系统的处理效果影响较大,污泥回流比减小,生物反应器中的细菌数量会逐渐减少,出水水质变差;污泥回流比过大,系统处理效果也会变坏,实验采用50%、100%和150%污泥回流比,污泥回流比为50%时脱氮除磷效果最好.混合液回流比为200%、300%和400%对TN、TP的去除研究表明:混合液回流比增大为反硝化提供了更多的基质,从而提高总氮的去除效果,但是随着混合液回流比进一步增加,不会提高氮的去除效果,反而使能耗大大增加.因此,运行条件优选为污泥回流比为50%,混合液回流比为200%.     

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.     

高回流比对序批式生物膜反应器脱氮性能的影响

硝化液回流是污水生物脱氮工艺实现前置反硝化脱氮的重要手段，通常回流比为200%～400%。本文研究了高回流比对序批式生物膜反应器(SBBR)脱氮性能的影响，结果表明，在回流比为300%、1 000%、3 000%三种条件下回流比为3 000%的总氮去除率最高，稳定运行期间TIN平均去除率为98.69%±0.81%，同时也使NH₄⁺-N得以完全氧化。推测在高回流比引起的强对流环境下，生物膜内传质效率得以加强，从而提高了同步硝化反硝化(SND)效果。本研究结果对集成分散式污水处理装置的研发及改善市政污水处理生物脱氮效率具有重要意义。     

多级SMBBR工艺处理低C/N比城市污水中试研究

通过中试试验研究多级SMBBR工艺(S/A/SMBBR)处理包头市某污水处理厂的低碳氮比生活污水的效能,考察SDC-03生物填料的挂膜启动及硝化液回流比、DO浓度和温度对脱氮效果的影响。结果表明,在15℃时,SDC-03填料在30 d左右完成挂膜,出水的COD和氨氮去除率70%左右;随硝化液回流比增加,NH_4~+-N平均去除率增加,TN去除率呈现先升高后下降趋势;回流比150%时,TN、NH_4~+-N的去除效果最佳;溶解氧(DO)浓度3 mg/L时,SMBBR工艺通过同步硝化反硝化(SND)实现最佳的脱氮效果。温度由15℃增加到30℃,脱氮效能增加,但效果不明显,多级SMBBR工艺对温度变化有良好的适应性。     

电极生物膜反应器中同步硝化反硝化的研究

为研究分隔式电极生物膜反应器(C-BER)在限氧条件下的硝化/反硝化,溶氧质量浓度约1mg/L时考察了低碳氮比时微电解对脱氮效果的影响。发现脱氮作用主要为同步硝化反硝化(SND)。碳氮的量比为1,电流为5mA和15mA时的平均TN去除率分别为33%和45%;碳氮的量比为0.5,电流为25mA并将30%出水回流,TN去除率可达60%,其中自养反硝化脱氮占51%。碳氮的量比为1,电流为15mA时,NH3-N去除率约为50%。碳氮的量比为0.5,电流25mA,NH3-N去除率增加到70%。两极之间SND脱氮量占总氮去除的64%。试验表明,提高电流和出水回流都有利于限氧条件下发生SND;微电解能促进硝化和反硝化作用。     

前置反硝化-BAF工艺反硝化池脱氮效能研究

为进一步提高反硝化(DN)池的反硝化效能,分别考察了进水温度、HRT、C/N以及反洗周期等因素对前置反硝化曝气生物滤池(BAF)组合工艺DN池的脱氮效能的影响。结果表明,反硝化效能会随温度的升高而升高,在25℃时NO_3~--N去除率为91.3%;水力停留时间对反硝化作用的影响主要原于HRT的减少缩短了反硝化作用的反应时间,从而使反硝化过程中所消耗的COD降低;COD/ρ(NO_3~--N)小于15时,COD/ρ(NO_3~--N)是DN池脱氮效能的决定性因素,当COD/ρ(NO_3~--N)大于15时,NO_3~--N的含量变化趋于平缓;同一反洗周期内DN池的反硝化效能会持续增加,下一反洗周期开始前NO_3~--N的质量浓度降低至1.9 mg/L,此时脱氮效能达到最大。     

生物颗粒循环量对循环流化床生物反应器性能影响的研究

采用100 g/d(阶段I)、50 g/d(阶段II)和200 g/d(阶段III)这3种不同生物颗粒循环量V_s操作循环流化床生物反应器(CFBBR)去除污水中的碳和氮,通过380 d的实验测试其处理合成废水的效果以及不同V_s对该反应器的性能影响。结果表明,3种V_s对CFBBR处理合成废水中的碳和NH_4~+-N基本无影响,其去除量分别稳定在95%和98%;而TN的去除率随着V_s的提高而略微增加,3个阶段分别为85.1%、88.8%和90%。V_s对硝化过程影响不大,所有阶段基本上都接近于完全的硝化反应。但对反硝化过程影响较大,低的V_s会降低缺氧床的反硝化效率,同时还发现生物膜厚度到达一定程度时,好氧流化床中可以发生同步硝化反硝化反应。     

多级SMBBR工艺处理低C/N比城市污水中试研究

通过中试试验研究多级SMBBR工艺(S/A/SMBBR)处理包头市某污水处理厂的低碳氮比生活污水的效能,考察SDC-03生物填料的挂膜启动及硝化液回流比、DO浓度和温度对脱氮效果的影响。结果表明,在15℃时,SDC-03填料在30 d左右完成挂膜,出水的COD和氨氮去除率70%左右;随硝化液回流比增加,NH_4⁺-N平均去除率增加,TN去除率呈现先升高后下降趋势;回流比150%时,TN、NH_4+-N平均去除率增加,TN去除率呈现先升高后下降趋势;回流比150%时,TN、NH_4⁺-N的去除效果最佳;溶解氧(DO)浓度3 mg/L时,SMBBR工艺通过同步硝化反硝化(SND)实现最佳的脱氮效果。温度由15℃增加到30℃,脱氮效能增加,但效果不明显,多级SMBBR工艺对温度变化有良好的适应性。     

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.     

Methyl 2,4,6-decatrienoates Attract Stink Bugs and Tachinid Parasitoids

Halyomorpha halys (Stål) (Pentatomidae), called the brown marmorated stink bug (BMSB), is a newly invasive species in the eastern USA that is rapidly spreading from the original point of establishment in Allentown, PA. In its native range, the BMSB is reportedly attracted to methyl (E,E,Z)-2,4,6-decatrienoate, the male-produced pheromone of another pentatomid common in eastern Asia, Plautia stali Scott. In North America, Thyanta spp. are the only pentatomids known to produce methyl 2,4,6-decatrienoate [the (E,Z,Z)-isomer] as part of their pheromones. Methyl 2,4,6-decatrienoates were field-tested in Maryland to monitor the spread of the BMSB and to explore the possibility that Thyanta spp. are an alternate host for parasitic tachinid flies that use stink bug pheromones as host-finding kairomones. Here we report the first captures of adult and nymph BMSBs in traps baited with methyl (E,E,Z)-2,4,6-decatrienoate in central Maryland and present data verifying that the tachinid, Euclytia flava (Townsend), exploits methyl (E,Z,Z)-2,4,6-decatrienoate as a kairomone. We also report the unexpected finding that various isomers of methyl 2,4,6-decatrienoate attract Acrosternum hilare (Say), although this bug apparently does not produce methyl decatrienoates. Other stink bugs and tachinids native to North America were also attracted to methyl 2,4,6-decatrienoates. These data indicate there are Heteroptera in North America in addition to Thyanta spp. that probably use methyl 2,4,6-decatrienoates as pheromones. The evidence that some pentatomids exploit the pheromones of other true bugs as kairomones to find food or to congregate as a passive defense against tachinid parasitism is discussed.     

2007～2008年世界塑料工业进展

收集了2007年7月～2008年6月世界塑料工业的相关资料,介绍了2007～2008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、不饱和聚酯树脂、环氧树脂)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.     

2005～2006年国外塑料工业进展

收集了2005年7月～2006年6月国外塑料工业的相关资料,介绍了2005—2006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生产量以及各国塑料制品的进出口情况。作为对比,介绍了中国塑料的生产情况。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（聚酰胺、聚碳酸酯、聚甲醛、热塑性聚酯、聚苯醚）、通用热固性树脂（酚醛、聚氨酯、不饱和树脂、环氧树脂）、特种工程塑料（聚苯硫醚、液晶聚合物、聚醚醚酮）的品种顺序,对树脂的产量、消费量、供需状况及合成工艺、产品开发、树脂品种的延伸及应用的扩展作了详细的介绍。