利用厌氧折流反应系统进行有机废水发酵制氢

以厌氧折流形式的发酵生物制氢反应器进行了连续流有机废水发酵产氢试验研究。反应器由有机玻璃制成,三格室,单格有效容积9.16L。以好氧生物处理系统剩余污泥为种泥,在容积负荷为8.89kg COD·(m~3·d)~(-1),水力停留时间为13.5 h,温度(35±1)℃等条件下,系统启动运行25 d后达到稳定运行状态。系统稳定运行时,总产气量和产氢量分别稳定在59.0 L·d~(-1)和32.0 L·d~(-1)左右。其中,第一格室、第二格室和第三格室的平均产气量及其氢含量分别为14 L·d~(-1)、25 L·d~(-1)、20 L·d~(-1)和50％、60％、50％。系统污泥的比产氢速率为76.64 L·(kg VSS·d)~(-1)。与同类生物制氢反应器相比,厌氧折流发酵生物制氢反应器具有结构简单、运行稳定、操作灵活、容积利用率高、生物持有量高以及运行费用较低等优点,在发酵生物制氢技术领域有很好的开发前景。     

“活性污泥-生物膜”杂合ABR制氢系统的启动与运行

对ABR系统进行改良,建立新型的"活性污泥-生物膜"杂合厌氧折流板生物制氢反应器(SMHABR),研究其乙醇型发酵的形成及其产氢及COD处理能力。反应器分为5个格室,有效容积43.2 L,实验共进行180 d。系统以红糖废水为原料,在HRT为12 h,温度为(35±1)℃,通过分阶段提高进水COD的方式,可使ABR系统在35 d内培育驯化形成乙醇型发酵菌群体系。进水COD在约3500 mg·L~(-1)时产氢量最大,总产氢量可达到44.75 L·d~(-1)。进水COD浓度达到约7100 mg·L~(-1)时COD去除率最大,平均总去除率可达到49.33%。COD去除率最大值并未与产氢量最大值同时出现,说明产氢最适进水浓度与COD去除最适进水浓度并非相同。     

生物制氢反应器启动的工程参数及其控制对策

研究了连续流生物制氢反应器(CSTR)启动的工程参数及其控制对策,选择了有机负荷作为生物制氢反应器启动的控制因子.结果表明,在污泥接种量VSS为17.74g/L的前提下,将进水有机负荷控制在8～16kg/(L·d),可在约12天就可以实现生物制氢反应器的快速启动.启动结束时,制氢反应系统内相应pH值和ORP稳定在4.32～460 mV;反应器产气量约为3 L/d,氢气含量达到75.77%;检测液相末端发酵产物,乙醇含量占44.58%,乙醇和乙酸的质量分数达到77.63%,为典型的乙醇型发酵.     

UASB反应器处理高含量核苷酸类废水启动特性研究

采用上流式厌氧污泥床(UASB)反应器,以高核苷酸类含量废水为处理对象,研究了中温条件下反应器的启动、颗粒污泥的特性和废水处理的效果.结果表明,采用消化污泥接种进行培养,逐步提高废水进水COD,运行109d后,UASB反应器正常启动;当进水COD达到11.2g·L-1 左右,COD容积负荷3.22 kg·m-3·d-1,COD去除率为80%以上;反应器启动完成后,粒径>0.3mm的颗粒污泥比例增加到13.61%,平均沉降速率为22.04-26.73m·h-1;反应器稳定运行后,每克COD产气量达到392 mL.反应器能高效稳定运行.     

厌氧发酵产氢污泥的驯化技术

以糖蜜废水为发酵底物,以污水处理厂剩余污泥为反应器启动污泥,污泥采用曝气氧化预处理方法,从而达到厌氧发酵产氢目的并提高其发酵产氢能力.试验表明,经曝气氧化预处理后的污泥可作为厌氧发酵生物制氢的接种污泥,且具有较高的产氢能力,在实验条件下,反应器稳定运行时产气量为3 L,发酵产气中氢气浓度为75.77%,液相末端发酵产物主要为乙醇、乙酸.     

多级生物膜反应器分段进水方式对脱氮效能影响研究

提出多级生物膜反应器,考察了分段进水方式对反应器处理城镇污水生物脱氮效能的影响.结果表明,分段进水点的数量、流量分配及容积分配对反应器脱氮效能的影响显著,分段进水方式有效地提高了碳源利用率以及反应器脱氮效能.在水温为25℃左右,溶解氧为5mg·L~(-1),挂膜密度为30%,COD负荷为1.2 kg·m~(-3)·d~(-1),总氮负荷为0.22 kg·m~(-3)·d~(-1)的条件下,反应器分段进水方式采用第1级、第3级、第6级分段进水,容积分配比为2:3:4,流量分配比为2:2:1时,可使出水COD为38 mg·L~(-1),出水NH_4~+-N和TN的质量浓度分别为1.5 mg·L~(-1)和11.1 mg·L~(-1),去除率分别为80.8%,95.3%和69.2%,与单点进水方式相比TN去除率提高了8.4%.     

水力停留时间对ABR系统处理红糖废水效果的影响

本实验研究所构建的反应器分为5个格室,有效容积43.2 L,实验共进行43天。通过分阶段减少HRT的方式,研究其产氢及COD处理能力。ABR系统以红糖废水为原料,在温度为35℃,进水COD约5000 mg·L~(-1),HRT为8 h时产氢量最大,平均总产氢量可达到13.15 L·d~(-1);HRT为12 h时,COD去除率最大,平均总去除率可达到49.17%。产氢量最大时的HRT(8 h)与COD去除率最大时的HRT(12 h)不同。     

EGSB反应器处理高浓度豆制品废水的研究

在中温(32～37℃)条件下,采用小试规模膨胀污泥床(EGSB)反应器处理高浓度豆制品废水(污水COD为1000～13000mg·L-1),连续运行180d,研究了进水COD、有机负荷(OLR)以及水力停留时间(HRT)等因素对废水处理效果的影响.研究利用好氧污泥接种成功培养出了高活性的厌氧颗粒状污泥.结果表明,EGSB反应器处理高浓度食品废水能够达到很好的效果,当进水COD有机负荷为2～6.75 kg·m3·d-1,HRT为48 h时,COD、BOD,去除率为85%左右;当进水COD为10000mg·L-1,最佳HRT为24h,此时相对应的OLR约为10-2kg·m-3d·d-1.稳定运行期间,厌氧反应器消耗每克COD的CH4产率为0.08～0.14 L·g-1,甲烷含量为60%～75%.试验达到了较好的处理效果和较高的产气率,表明应用EGSB处理高浓度豆制品废水是高效、可行的.     

CSTR和ACR丁酸型发酵制氢系统的运行特性比较

为寻求更好的连续流发酵生物制氢反应器模式,以稀释糖蜜为底物,控制反应系统为丁酸型发酵,比较研究了搅拌槽式反应器（CSTR）和厌氧接触式反应器（ACR）的启动运行特性。结果表明,以经曝气培养的下水道污泥为接种物,在接种量4.8 g MLVSS·L^-1、进水COD 5000 mg·L^-1、HRT 12 h、温度（35±1）℃和pH 5.5～6.0等相同条件下,CSTR系统可以更快地达到稳定的丁酸型发酵状态,而ACR系统因其有效的生物持有能力而在产氢性能方面更具优势。在稳定运行状态下,ACR系统的底物酸化率、产氢速率和污泥的比产氢速率分别为44%、9 L·d^-1和0.15 L·(g MLVSS·d)^-1,分别是CSTR系统的1.62、2.05和1.15倍。     

垂直式厌氧好氧一体化反应器的快速启动

通过对内循环(IC)厌氧反应器进行改进,使其成为垂直式厌氧好氧一体化组合工艺,实现对高浓度DHA废水的耦合处理。试验采用高负荷、高进水浓度的方式对反应器的启动进行了分段研究,并分别对厌氧及好氧段有机物降解进行了效能分析。研究表明,启动初期采用DHA废水与生活污水混合进水的方式并控制反应器在中温条件下运行,可完成对反应器的快速启动。经60 d的调试运行,一体化反应器中厌氧段容积负荷达到10 kg COD/(m~3·d),COD去除率稳定在60%左右,好氧段容积负荷达到4 kg COD/(m~3·d),出水COD小于500 mg/L,满足《污水排入城镇下水道水质标准》(CJ 343-2010)。60 d后厌氧段颗粒污泥形状规则、密实,经扫描电镜观察发现,污泥表面具有较大孔隙且杆状菌占优势,好氧污泥在电子显微镜下可观察到钟虫。     

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.