电化学联合酸法对污泥脱水性能的影响

剩余污泥处理处置是当今社会的一大难点。要解决污泥产量大的问题,一个关键要素就是要提高脱水效率,改进脱水技术。探讨了电化学联合酸法对污泥脱水性能的影响,通过分析污泥含水率和毛细吸水时间来探究电解电压、极板间距、电解时间和极板插入深度对脱水的影响。实验结果显示:电化学联合酸法的最佳污泥脱水条件为极板间距6cm、极板插入深度6cm、电解时间30min、电解电压15V和pH为4。此时,污泥含水率降低9.04%,毛细吸水时间下降了42.6%。     

化学调理法改善污泥脱水的研究进展

污水处理过程中会产生大量的污泥,污泥的性质、组分和各种外界因素导致污泥具有较高的含水率且难以脱水。传统的机械脱水已不能满足污泥处置的要求,高含水率已成为污泥处理的瓶颈。详细分析了影响污泥脱水的因素,归纳了化学调理在污泥脱水方面的应用,阐述了不同调理剂对污泥脱水的作用机理,总结了不同调理剂复配的协同增效作用对污泥脱水的影响,以期为今后的污泥脱水研究提供参考。     

污泥深度脱水分析和全自动压滤机应用实践

从过滤速率方程可见，影响污泥深度脱水的主要因素有污泥性质(r、μ)、压力、泥饼厚度和时间。通过污泥调理、增加压力、降低泥饼厚度可以改善污泥的脱水效率和脱水后泥饼含水率，但要同时考虑经济性、安全性和污泥减量化、稳定化、无害化和资源化的需要。滤布行走式全自动压滤机，可以实现无人辅助卸泥全自动运行，单一调理剂聚合硫酸铁有效投加量占绝干污泥的比例为1.47%～2.1%,泥饼含水率50.15%～53.45%。     

污泥深度脱水调理剂对污泥干化过程中含硫气体释放的影响

采用5种复合调理剂改善污泥脱水性能,制得深度脱水泥饼。通过检测N2气氛下,不同干化温度(100℃、200℃),停留时间(30 min、60 min)时,不同调理脱水污泥含水率的变化情况,以及含硫气体的种类和释放量,探讨不同调理剂对干化过程中含硫气体释放特性的影响。结果表明,提高温度、延长时间都可以有效降低污泥的含水率;原污泥干化过程释放的主要含硫气体为H2S和SO2,其总量占含硫气体的82.4%;FeCl3+CaO和H2SO4+FeSO4+H2O2+CaO复合调理剂调理脱水泥饼在干化过程中SO2释放量占原污泥释放量的40.3%和40.6%,H2S则基本没有释放;H2SO4+FeSO4+H2O2+CaO调理脱水污泥在100℃和200℃干化过程中的总硫释放量分别占原污泥总释放量的75.0%和45.6%,该复合调理剂在有效提高污泥脱水性能的基础上,能最大限度地抑制含硫气体的释放。     

PAC调理剂对全自动板框压滤机污泥深度脱水的影响

传统板框脱水采用"石灰+FeCl3"作为污泥调理剂,存在干基增量大、泥饼热值较低、作业环境较差等问题.通过中试试验考察了PAC对污泥深度脱水过程的影响.结果表明:随着PAC投加量增高,脱水泥饼含水率降低;滤室中污泥含水率变化速率随着隔膜挤压时间的延长逐渐减缓;当进料浓度从3.3％提高到7.6％时,压滤机过滤速率明显提高了40％左右.相较于传统污泥调理剂,采用PAC作为污泥调理剂可使污泥热值较高、干基增量较小,可显著提高污泥焚烧经济价值.     

电渗透污泥脱水的影响因素分析及响应曲面优化

利用电渗透技术,采用自制装置对市政污水厂的脱水污泥进行深度脱水,研究了机械压力、初始含水率、电压梯度和污泥厚度等对污泥脱水的影响,在此基础上利用响应曲面法,以污泥含水率降低率为响应指标,根据BoxBenhnken中心组合实验设计,对污泥电渗透脱水工艺参数进行了优化。结果表明,电渗透技术可以改善污泥的脱水性能,当机械压力为18.83 k Pa,污泥厚度为1.13 cm,电压梯度为60 V/cm,初始含水率为87.45%时,污泥含水率可降至49.14%。     

深度脱水污泥的热干化特性

深度脱水污泥中调理剂对其干化特性有着重要影响。实验采用4种典型复合调理剂对污泥进行预处理,制得脱水污泥,在N_2气氛、473 K条件下,探究调理剂对污泥干化过程中水分和污染物释放以及干化气、液、固产物特性的影响。结果表明,所用复合调理剂均可以有效降低脱水污泥含水率,加快干化阶段水分释放速率;调理过程中的酸碱及强氧化环境能破坏污泥中的有机结构,使污泥中的芳香族或噻吩S转化为更加稳定的磺酸或砜类S,且调理后的碱性环境让溶解的酸性含硫气体固定,从而使得干化时含硫气体释放量减少,但会加速氨气的释放。干化时复杂的气相产物溶解于冷凝液使其具有较高的pH以及COD并伴有恶臭,需进行进一步处理;污泥热干化后样品热值降低量在3.63%以内,不影响其能源化利用。     

污泥深度脱水调理剂对污泥干化过程中含硫气体释放的影响

采用5种复合调理剂改善污泥脱水性能,制得深度脱水泥饼。通过检测N₂气氛下,不同干化温度（100℃、200℃）,停留时间（30 min、60 min）时,不同调理脱水污泥含水率的变化情况,以及含硫气体的种类和释放量,探讨不同调理剂对干化过程中含硫气体释放特性的影响。结果表明,提高温度、延长时间都可以有效降低污泥的含水率;原污泥干化过程释放的主要含硫气体为H₂S和SO₂,其总量占含硫气体的82.4%;FeCl₃+CaO和H₂SO₄+FeSO₄+H₂O₂+CaO复合调理剂调理脱水泥饼在干化过程中SO₂释放量占原污泥释放量的40.3%和40.6%,H₂S则基本没有释放;H₂SO₄+FeSO₄+H₂O₂+CaO调理脱水污泥在100℃和200℃干化过程中的总硫释放量分别占原污泥总释放量的75.0%和45.6%,该复合调理剂在有效提高污泥脱水性能的基础上,能最大限度地抑制含硫气体的释放。     

高温热水解预处理对污泥脱水性能影响的中试试验

在小试基础上,以江苏某污水处理厂混合污泥为研究对象,研究中试规模高温热水解对污泥脱水性能、离心脱水进泥温度及不同脱水方式对热水解污泥脱水性能的影响。结果表明:热水解预处理能显著提高污泥的脱水性能,并随热水解温度和时间升高、延长而增强;含水率为90.9%的污泥,在180℃、30 min热水解条件下,无需加药,离心脱水和板框压滤脱水产物含水率小于60%,分别达到56.8%和45.2%。就出料含水率来说,在120℃和150℃、30 min热水解预处理条件下,离心脱水具有一定优势,但在180℃条件下的板框脱水更具优势。     

深度脱水污泥的热干化特性

深度脱水污泥中调理剂对其干化特性有着重要影响。实验采用4种典型复合调理剂对污泥进行预处理,制得脱水污泥,在N₂气氛、473 K条件下,探究调理剂对污泥干化过程中水分和污染物释放以及干化气、液、固产物特性的影响。结果表明,所用复合调理剂均可以有效降低脱水污泥含水率,加快干化阶段水分释放速率;调理过程中的酸碱及强氧化环境能破坏污泥中的有机结构,使污泥中的芳香族或噻吩S转化为更加稳定的磺酸或砜类S,且调理后的碱性环境让溶解的酸性含硫气体固定,从而使得干化时含硫气体释放量减少,但会加速氨气的释放。干化时复杂的气相产物溶解于冷凝液使其具有较高的pH以及COD并伴有恶臭,需进行进一步处理;污泥热干化后样品热值降低量在3.63%以内,不影响其能源化利用。     

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.     

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.     

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。