矿化垃圾对污泥厌氧消化产甲烷的影响

在序批式厌氧反应器中探究了矿化垃圾对污泥厌氧消化产甲烷的影响。实验结果表明,矿化垃圾能够提高甲烷的产量并且提高甲烷的体积分数。当矿化垃圾投加量由0增加到5 g·L~(-1)时,甲烷的产量也由168.9 m L·(g VSS)-1(挥发性悬浮固体)增加到218.6 m L·(g VSS)-1,体积分数由60%增加至70%。然而继续提高矿化垃圾的投加量至7 g·L~(-1)对污泥厌氧消化造成一定的抑制作用。矿化垃圾的存在能够提高污泥中溶解性化学需氧量(SCOD)的溶出,挥发性脂肪酸的积累进而为产甲烷菌提供了充足的消化底物,从而提高了甲烷的产量。     

以有机酸为共基质硝基酚厌氧生物降解性研究

在中温厌氧消化条件下 ,以有机酸 (乙酸与丙酸的混合酸 )为共基质 ,通过测定甲烷累积产量 ,研究了 2 硝基酚、2 ,4 二硝基酚的厌氧生物降解性。试验条件为 :温度 35℃ ,COD 110 0～ 12 0 0mg/L ,pH 7 0～ 7 5 ,COD/VSS为 0 1,接种污泥未驯化 ,其产甲烷活性CH4/VSS为 195mL/g。研究结果表明 ,在所选的浓度范围内 (≤ 4 4mg/L) ,2 硝基酚对产甲烷过程没有产生抑制作用 ;2 ,4 二硝基酚是抑制性较强的物质 ,浓度为 12～ 2 0mg/L时产生中度抑制 ,大于 2 8mg/L时产生重度抑制     

碳氮比对鸭粪中温厌氧消化的影响

在中温(35±1)℃、6%的料液浓度、pH为中性条件下,采用10 L玻璃瓶作为反应器对碳氮比(C/N)分别为15、20、25和35的4组鸭粪溶液进行厌氧消化实验,系统运行30 d,分析了厌氧消化过程中的COD(化学需氧量)、pH、VFA(挥发性脂肪酸)和产气量的变化。结果表明,碳氮比是影响鸭粪厌氧消化过程的重要因素,调节鸭粪碳氮比至25,可以使其厌氧消化获得最佳的产气效果,COD去除率为24.06%,原料干物质产气率为0.178 m3/kg,产气中甲烷含量为71.5%,产甲烷率为0.127 m3/kg。     

脂肪酶对餐厨垃圾厌氧产气的影响

在序批式厌氧反应器中探究了脂肪酶对餐厨垃圾厌氧消化的影响,结果表明脂肪酶能强化甲烷的积累量,且最佳的脂肪酶投加量为0.4 g·L~(-1),相应的甲烷积累量为356 m L·g~(-1)VSS,该数值是空白对照组的1.3倍。进一步机理研究表明脂肪酶能够促进溶解性COD的释放,提高生物脱氢酶的活性而减少长链挥发性脂肪酸的积累,进而提高甲烷的积累量。     

污泥的高温微好氧消化-厌氧消化工艺研究

城市污泥含有大量有机物和病原菌,需要稳定化处理。采用新型工艺高温微好氧与中温厌氧两级消化工艺(ATMD-MAD)处理城市污泥,与全程厌氧消化工艺(MAD)相比,不仅回收能源气体甲烷,而且缩短稳定化停留时间。55℃高温微好氧消化停留时间为2 d,后接35℃中温厌氧消化共运行24 d。结果表明,在ATMD-MAD系统中污泥的挥发性悬浮固体VSS去除率能在22 d时达到污泥稳定化要求的40%以上。ATMD-MAD工艺的单位VSS甲烷产量最高为496 m L/g VSS高于MAD工艺。在消化的前14天,可溶性挥发有机酸VFA在ATMD-MAD系统中的总量比MAD高出20%;在消化的第2天,ATMD-MAD系统中可溶性COD(SCOD)高出MAD工艺43.8%。ORP的变化反映了ATMD-MAD工艺保持了较好的厌氧状态,消化开始时的头2天限量曝气并没有给厌氧带来冲击。     

上流式厌氧污泥床反应器处理饮料废水

通过监测西安可口可乐饮料有限公司污水处理站的上流式厌氧污泥床(UASB)反应器,探讨饮料废水厌氧处理过程中COD去除率、沼气组分、氢分压、出水挥发性脂肪酸、产甲烷活性以及污泥形态。结果表明,UASB反应器对饮料废水中的COD去除率达到84.55%,产生的沼气中甲烷组分含量高达74.5%。反应器内的氢分压仅2.5 Pa,为水解发酵和产氢产乙酸过程创造了良好的条件。UASB反应器中污泥具有较高的产甲烷活性,以乙酸、丙酸和丁酸为基质时,最大比产甲烷活性分别为407.14、331.74和241.27 m L CH4/(g VSS·d)。UASB反应器中的污泥形态主要为絮状,甲烷菌中的优势菌为甲烷丝菌,同时存在少量甲烷杆菌。针对该厂UASB反应器中污泥的现状,提出了影响颗粒化的因素和控制措施,为后期的运行和管理提供了参考依据。     

氨氮浓度对猪粪厌氧消化及产甲烷菌群结构的影响

氨氮抑制是影响高含固厌氧消化推广应用的主要因素之一。通过批式实验,采用外源氨氮投加方式,考察了厌氧消化过程中不同氨氮浓度对鲜猪粪产甲烷效果和产甲烷菌群结构的影响。结果表明:氨氮添加量为2 000 mg·L~(-1)(TAN≈3 596.7 mg·L~(-1))时,日产甲烷速率及累积产甲烷量均明显下降;添加量大于4 000 mg·L~(-1)(TAN≈5 618.7 mg·L~(-1))时,氨氮抑制加剧,出现VFAs累积、产甲烷高峰期后移、丙酸降解失败。不同氨氮投加量下猪粪中挥发性固体(VS)产甲烷率分别为(369.0±17.3)、(318.5±7.6)、(234.7±2.5)、(165.4±19.4)mL·g~(-1),产甲烷效率较对照组分别下降14%、36%和55%。超过4 000 mg·L~(-1)的外源氨氮投加促使产甲烷菌群结构发生显著变化,乙酸利用型产甲烷优势菌Methanosaeta逐渐被Methanosarcina代替,而氢利用型产甲烷菌属中Methanospirillum的优势性逐渐被Methanoculleus和Methanomassiliicoccus取代,说明后者均有较强的氨氮耐受性。主成分分析和冗余分析表明,高浓度氨氮会促使产甲烷途径由乙酸利用型为主向氢利用型为主转变。     

废水中2,6-二硝基酚厌氧毒性和降解动力学研究

在中温(35℃±1℃)厌氧条件下,以葡萄糖为共基质,采用间歇实验方法,研究了2,6-二硝基酚(2,6-DNP)的厌氧产甲烷毒性和厌氧降解动力学.厌氧毒性试验(ATA)以累计产甲烷量和相对活性(RA)为指标,评价了不同浓度2,6-DNP对产甲烷菌的抑制程度;结果表明,2,6-DNP浓度＜20 mg/L时,对产甲烷菌没有抑制作用,浓度为40 mg/L时产生轻度抑制,浓度为80～120 mg/L时产生重度抑制;24 h 2,6-DNP的75%、50%、25%相对抑制浓度分别为30、70和＞120 mg/L.2,6-DNP降解动力学可用Haldane方程来描述,利用非线性拟合求得动力学参数Ks、Rm、Ki分别为179.7 mg/L、4.84 mg/g VSS·h、206.5 mg/L,方差R2=0.94,拟合效果很好.     

以有机酸为共基质硝基酚厌氧生物降解性研究

在中温厌氧消化条件下，以有机酸(乙酸与丙酸的混合酸)为共基质，通过测定甲烷累积产量，研究了2-硝基酚、2，4-二硝基酚的厌氧生物降解性。试验条件为：温度35℃，COD1100～1200mg／L，pH7．0～7．5，COD／VSS为0．1，接种污泥未驯化，其产甲烷活性CH4／VSS为195mL／g。研究结果表明，在所选的浓度范围内(≤44mg／L)，2-硝基酚对产甲烷过程没有产生抑制作用；2，4-二硝基酚是抑制性较强的物质，浓度为12～20mg／L时产生中度抑制，大于28mg／L时产生重度抑制。     

蒸汽爆破对脱水污泥溶解性和厌氧消化性能的影响

利用蒸汽爆破装置对脱水污泥进行了预处理,研究蒸汽爆破对污泥溶解性和厌氧消化性能的影响。结果表明,经汽爆处理后污泥的絮体结构遭到部分破坏,1 MPa条件下的汽爆污泥液相中可溶性糖、挥发性脂肪酸和DNA的浓度较原污泥分别提高了806.38%、577.36%和300%,BOD5/TCOD上升了35.58%;厌氧消化过程中累积产气量和甲烷平均含量分别为320 m L和42.32%,比未处理污泥提高了611.11%和726.56%;VFAs和氨氮平均浓度分别达到107.0 mg/L和1 758.7 mg/L。同时,压强升高可进一步改善污泥溶解性和厌氧消化性能。     

Optimization of Height of Release of Air Pollutants

A number of key projects in the Environmental Protection Agency (EPA) particulate R&;D program having applicability to industry are presented. For electrostatic precipitators (ESP) there is presented the result of work on large diameter discharge electrodes which provide a decrease in penetration of up to a factor of 4 when compared to conventional small diameter electrodes. Also discussed is the multistage ESP which provides a collection efficiency that would require a collecting plate area 4 or 5 times larger with conventional ESP technology. The E-SOX technology makes use of the multistage concept to free up space in the ESP for SO₂ removals of up to 90%. Electrostatically augmented fabric filtration provides a reduction in pressure drop of about 5 0% as compared to conventional fabric filtration. Wind tunnel modeling of windbreaks for material storage piles indicates a potential for providing engineering design data that would allow significant emission reduction caused by wind erosion     

Investigation of the characteristics of the reflectivity of clouds

This paper investigates some of the reflectivity characteristics that clouds (when modelled as solid bodies) must exhibit to be compatible with observations that the reflecting surface of a cloud (i) appears almost equally bright across its face, (ii) is brightest when the cloud is opposite to the Sun but decreases in brightness as the cloud moves to other positions and (iii) increases in brightness with increasing optical thickness of the cloud in the observer's line of sight. These observations, respectively, are shown to imply that the peak value of the bidirectional total reflectivity from a cloud surface (i) increases in inverse proportion to the cosine of the angle between the Sun and the normal to the cloud surface, as the incident angle increases, (ii) appears to be directed back in the direction of the incident radiation, and (iii) increases as optical thickness of the cloud in the observer's line of sight increases. The results could have application in many fields (e.g. modelling diffuse radiance distributions for cloudy skies).     

Estimation of uncertainty of sampling for analysis of pesticide residues

Abstract

A computer model was used to take random samples from primary sample populations obtained from field trials to simulate the uncertainty of sampling for residue analysis of plant commodities and soil. The results indicate about 40%, 30% and 20% relative uncertainty when random samples of size 5, 10 and 25 are taken respectively, from a single lot. Therefore the sample size should be the same for establishing and enforcing legal limits.     

扬中生态环境建设的思考与实践

结合扬中生态环境的基本情况和存在的不足，进行了具体分析，对扬中未来生态建设的发展方向提出了建议及实施措施。     

An application of the theory of kinematics of mixing to the study of tropospheric dispersion

The most common technique used for numerical simulations of tracer mixing is that of the numerical solution of the advection–diffusion equation with the unresolved fluxes parameterized using the similarity theory. Despite correct predictions of the overall directions of transport, models based on a numerical solution of the advection–diffusion equation lack sufficient accuracy to correctly reproduce the coupling of mixing with small scale processes which are sensitive to the microstructure of the tracer distribution. The objective of this paper is to revisit the basic formalism employed in numerical models used to investigate atmospheric tracers. The main mathematical method proposed here is the theory of kinematics of mixing which could be applied effectively for simulations of atmospheric transport processes. At the beginning of the paper, we introduce simple mathematical transformations in order to demonstrate how complex topological structures are created by mixing processes. These idealistic flow systems are essential to explain transport properties of much more complex three-dimensional geophysical flows. An example of the application of the kinematics of mixing to the analysis of tracer transport on a planetary scale is presented in the following sections. The complex filamentary structures simulated in the numerical experiment are evaluated using some commonly applied statistical measures in order to compare the results with the data published in the literature. The results of the experiment are also analysed with the help of simple conceptual models of fluid filaments. The microstructure of the tracer distribution introduced in the paper is essential to increase our understanding of atmospheric transport and to develop more realistic parameterizations of small-scale mixing. The presented results could also be used to improve calculations of the coupling between microphysical processes and tracer mixing.     

次氯酸钠发生器的研制

介绍了电解法生产次氯酸钠的原理 ,并在原有生产工艺的基础上进行了重新设计和对设备的重新选择、改造 ,得出了各个工艺参数的最佳值 ,生产出高品质的次氯酸钠     

实验室质量管理体系内部审核的实施

在实施ISO／IEC17025：1999标准《检测和校准实验室能力的通用要求》过程中，通过实验室质量管理体系内部审核的实践与系统分析，识别出内部审核实施阶段的关键环节，提出召开首次会议、收集审核证据、确定审核发现和召开末次会议的技术方法，对提高内部审核的质量和有效性、获得可靠的审核结论具有重要意义。     

实验室质量管理体系内部审核的策划

在实施ISO／IEC 17025：1999标准《检测和校准实验室能力的通用要求》过程中，通过实验室质量管理体系内部审核的实践与系统分析，识别出内部审核策划阶段的关键环节，提出审核范围确定、审核计划和抽样方案制订的质量控制要求，为有序高效地实施内部审核提供了技术方法。     

Characterization of products of ozonolysis of acrylonitrile in liquid phase

In order to elucidate the reaction mechanism of the ozonolysis of acrylonitrile in the liquid phase, characterization of reaction products has been attempted. One of the products, which was volatile, has been found to be formaldehyde by derivatizing with dimedone. The infrared and mass spectra of the derivative corresponded with that of alkylidene dimedone. Three other reaction products were isolated by TLC using silica gel, CHCl₃:MeOH (80:20). These have been tentatively identified as glyoxal, epoxide of acrylonitrile and acetamide from their mass spectra. Based on these findings a reaction pathway for the formation of formaldehyde is proposed to be that described by Criegee.