城镇污泥热水解与厌氧消化联用技术的原理、效能及应用

污泥厌氧消化在实现污泥减量化、无害化的同时,能够实现污泥中有机物的资源化和能源化,是我国政府主推的污泥处理处置技术之一。为了提高污泥厌氧消化的效率,污泥热水解预处理技术常作为污泥厌氧消化的前处理技术,并已得到工业化应用。污泥热水解预处理技术能够提高污泥的产气率,提高系统的稳定化运行效能。在分析污泥热水解和污泥厌氧消化技术特征的前提下,对当前主要使用的污泥热水解和厌氧消化技术相应的配套装备进行了介绍,分析单元/组合技术的优势,并以实际案例为支撑凝练了各装备的运行效能。在此基础上,对"污泥热水解+厌氧消化装备"的未来发展前景进行了预测。     

电化学预处理对后续厌氧消化工艺的作用研究

研究了经过电化学预处理后污泥性质的变化以及对后续厌氧消化工艺的改善,从产气效果、消化性能、脱水性能、污泥性质4个方面来体现电化学预处理的改善作用。结果表明,经过电化学预处理的厌氧消化工艺其污泥日产气量最大达到12.19 m L/g,远大于未经预处理的全程厌氧工艺。经过电化学预处理与厌氧消化耦合工艺后,污泥上清液中挥发性有机酸(VFA)含量、SCOD、碱度、p H都大于全程厌氧工艺,其中SCOD最大达到2 951 mg/L、VFA的质量浓度最大达到485.3 mg/L;25 d厌氧消化后,污泥经过耦合工艺处理后VSS去除率为42.13%,而全程厌氧工艺处理后VSS去除率只达到33.23%。因此,可以说明电化学预处理可以改善后续厌氧消化工艺。     

污水处理工艺对污泥热解半焦热解特性的影响

通过在升温速率10℃/min和氮气氛围下的热重实验,对来自3个污水处理厂的5种污泥在450℃下热解制得半焦的热解特性进行了研究。结果表明,5种半焦的热解过程均为水分析出、缓慢失重、挥发分析出和残余物分解4个阶段。污水处理工艺中的厌氧过程和污泥厌氧消化使半焦中的有机物复杂化;污泥厌氧消化改善了半焦的热解性能,污水处理工艺中的"厌氧+好氧"和"好氧+厌氧"过程则降低了半焦的热解性能,其中"好氧+厌氧"过程对半焦热解性能的影响异于其对污泥热解性能的影响;半焦热解时的第三阶段与污泥的第四阶段相对应,但并非是简单的对应。利用Coats-Redfern法对5种半焦热解机理的研究结果表明,5种半焦的机理函数彼此不完全相同,但半焦热解活化能均低于污泥的。     

微波/碱/活性炭纤维联用预处理污泥的厌氧消化效果

试验考察了在碱性条件下,以活性炭纤维为催化剂,微波诱导氧化预处理对污泥厌氧消化效果的影响。试验结果表明,预处理能有效地提高污泥的厌氧消化性能。经过预处理后,污泥在厌氧消化过程中平均日产气速率是50.5mL/d,比原污泥增加了64%;污泥总产气量比未预处理前增加了63.7%;厌氧消化后污泥的总COD去除率达到50.4%,比未经过预处理的大10.4%。消化过程中污泥单位VSS的产气率由没经过预处理的215.7mL/gVSS提高到272.2mL/gVSS。     

浅议城市污水处理厂污泥处理技术路线

通过分析我国城市污水处理厂产生的不同类型污泥的特性,介绍了污泥"减量化"、"无害化"和"资源化"的技术措施及三者之间的关系,重点对减量化的工艺予以综述,提出了不同的减量化理念。在污泥资源化利用方面,通过详细介绍3个典型的污泥处理案例,将厌氧消化产沼气工艺、高温热水解-厌氧消化联合工艺和建材化水泥窑煅烧工艺进行了对比,阐述了不同工艺具有的优缺点。     

城市污泥高级厌氧消化工程案例

针对我国污水处理厂污泥传统厌氧消化降解率较低、产气率低的问题,采用了一种先进的"污泥热水解+高含固厌氧消化+脱水+干化+沼气干式脱硫"组合处理工艺。工程运行结果表明,系统抗冲击能力强、运行效果良好,厌氧消化段污泥含固率可达10%以上,平均VS降解率高于42%,沼气产率约为0.37 m~3/(kg VS_(投加)),即0.88 m~3/(kg VS_(去除))。     

污水污泥厌氧消化的超声预处理研究进展

超声预处理是促进污水污泥厌氧消化的较佳技术.从厌氧消化及超声作用原理出发,对超声预处理强化污水污泥厌氧消化的影响因子(底物因子及操作因子)进行了分析,并对其应用前景进行了展望,提出了其今后的研究方向.     

水热预处理对剩余污泥有机物释放的影响

针对剩余污泥中有机能源利用率低的问题,研究了水热预处理对剩余污泥有机物释放及污泥厌氧消化过程中累积产气量的影响。结果表明:水热处理是一种有效的污泥预处理方法,当水热温度为200℃、水热时间为1 h时,污泥减量度达76.56%,污泥SCOD为原泥的34倍,大大减少了污泥固相有机物含量。经水热处理后,污泥厌氧消化最大产气量为2 950 m L,较原泥提高了69%;厌氧消化后,水热预处理污泥SCOD减少量为原泥的30倍。     

预处理对烯烃厂剩余污泥厌氧消化处理效果的影响研究

随着宁夏煤化工产业发展进程的不断加快,配套建设的污水处理厂也日益增多,其大都采用生化处理工艺,产生了大量的剩余污泥。研究了宁东烯烃厂剩余污泥经超声波和热预处理后再进行厌氧消化的处理效果,结果表明:宁东烯烃厂的剩余污泥经预处理后再进行厌氧消化,绝大部分溶解性有机物在污泥停留时间为9 d的时候,就基本降解到一个稳定状态。预处理不但可以提高厌氧消化反应中有机物的去除率,而且可以大幅度缩短污泥消化时间,促进厌氧消化速率。     

污泥预处理-厌氧消化体系的能源经济性评价

在污泥的厌氧消化中，降低过程能耗与提高甲烷产量是实现污水处理系统“碳中和”的主要思路之一。热、化学、机械预处理是打破厌氧消化限速水解的有效手段，主要着眼于甲烷增产以形成更多的“碳补偿”。但从热力学角度，预处理是通过消耗电能、热能、化学能使有机物大量溶解，从而获得更多生物质能的过程，其本身作为一种能量输入形式增加了厌氧消化的能耗。以往的研究通常以污泥液相中有机物溶出、固相中有机物去除以及甲烷产量作为厌氧消化性能的评价指标，难以客观评估各类厌氧消化预处理的实际效益。本文从能源转换的角度出发，综述了各类污泥预处理方法的作用机理及对厌氧消化的抑制因子等方面的研究进展，对比了典型的热预处理、碱预处理、超声预处理及其联合处理分别在甲烷产量、净能量和净利润等指标上的研究结果，并在污泥厌氧消化效率评价基础上分析了上述预处理方法在能源和经济层面的可行性，为预处理方法和预处理条件的选择提供多维度依据。     

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.     

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.     

Highly moisture-proof polysilsesquioxane coating prepared via facile sol-gel process

A highly moisture-proof polysilsesquioxane coating was obtained from a new bis-silylated precursor, which was synthesized from 3-aminopropyltriethoxysilane (APTES) and m-xylylene diisocyanate (m-XDI) in tetrahydrofuran (THF) and verified by ¹H MAS NMR. For direct comparison purposes, an SiO₂ coating was also prepared by the Stöber method using tetraethoxysilane (TEOS) as the reactant. Interestingly, the coating obtained from the polysilsesquioxane sol exhibited a much higher moisture resistance capability than its counterpart, which was attributed to its more compact feature between nanoparticles as characterized by N₂ absorption experiment and transmission electron microscopy (TEM). Furthermore, its high transparency of about 92% showed potential for application in the protection of optical crystals.