胞外聚合物对膜生物反应器运行性能的影响

膜生物反应器处理污水过程中,依据胞外聚合物(EPS)、蛋白质、多糖、粘度等参数随时间的变化趋势以及对膜通量的影响,求出上述参数及蛋白质/多糖的比值与膜通量间的相关系数分别为0.28、0.57、0.38、0.14、0.70。结果表明:蛋白质/多糖的比值与膜通量的衰减速度两者相关系数最大。     

膜生物反应器中膜污染机理及其防治

通过向一体式膜生物反应器中分别投加聚合铝和粉煤灰改变料液性质,来预防膜污染和提高膜生物反应器对总磷的去除效率,并通过X射线衍射和红外光谱实验分析活性污泥性质的变化,利用扫描电镜分析中空纤维膜表观结构的变化情况,探讨防治膜污染的机理.实验结果表明:聚合铝的投加改变了活性污泥的性质和生物膜的表观结构,可有效地减缓膜污染,且除磷效率达85%以上;而投加粉煤灰并没有明显效果.     

膜蒸馏处理糠醛废水的实验研究

采用中空纤维膜蒸馏技术研究了糠醛废水的膜蒸馏处理效果,考察了料液相的温度、醋酸浓度、流速、吸收液浓度等因素对处理效果的影响。结果表明：在温差为15℃、料液的浓度为0.306 mol/mL时,速度为8 mL/min;吸收液的质量浓度为25 g/L时,速度为3 mL/min。运行12 h后,料液的pH值由开始的1.9升高为5.1,醋酸的去除率为76.3％,糠醛的去除率为40.1％。此过程可降低料液中糠醛和醋酸的含量,减小了低分子量有机酸对微生物危害的影响,为后续生物处理奠定了基础。     

膜蒸馏处理乳化油废水的实验研究

采用自制的中空纤维膜蒸馏组件对模拟的乳化油废水进行膜蒸馏处理研究, 分析了料液的浓度、流速、温度和处理时间等因素对膜通量及去除率的影响。实验结果表明: 在料液温度为50℃、流速为14 mL /min、乳化油浓度为500 mg/L 的条件下, 运行1 h后乳化油膜通量为21.20 g/m2 ·h, 去除率> 70%; 运行5 h后膜通量下降为5.141 g/m2 ·h, 去除率> 90%。     

投加粉末活性炭对MBR运行性能的影响

试验研究比较了在相同的进水和运行条件下,反应器1(投加粉末活性炭,投加量为12.3 g,使其质量浓度达到1 100 mg/L)和反应器2(未投加粉末活性炭)的膜透水性及对污染物的去除效果,并分析了粉末活性炭可以提高膜过滤性能的相关机理。试验结果表明：反应器1的膜通量衰减速率明显小于反应器2;投加粉末活性炭改变了混合液的性质,也大大降低了混合液中胞外聚合物和微细胶体的含量,从而减缓了膜通量的下降速度,可以使系统长时间地以相对高的膜通量运行。     

结晶膜蒸馏处理吸收炼矿烟气酸性废水的研究

采用天然碳酸钙中和烟气吸收酸性废水,研究中空纤维结晶膜蒸馏技术对中和后废水处理的效果。考察了料液温度、起始浓度、流速、pH值等因素对膜通量的影响。在选定的条件下对水样进行连续膜蒸馏处理。结果表明,在料液温度50℃,料液速度为18.5mL/min,pH值为7,运行18h后,浓缩溶液开始出现结晶,结晶效果较好。截留率均接近100%。     

气态膜回收氰化物的研究

气态膜是一种新型的膜分离技术,适用于从水溶液中分离提取挥发性物质。本文对气态膜回收氰化物的迁移机理及各种影响因素进行了研究,结果表明：传质速率与料液浓度呈现线性递增关系;吸收液浓度、流速和料液浓度、流速在一定范围内影响传质速率;温度升高,传质加快;膜孔径及孔隙率增大,传质速率也随之增大。     

固体停留时间对HLB-MR反应器直接回收城市污水中有机物的影响

为优化高负荷生物絮凝-膜反应器（HLB-MR）的工艺参数,提高其资源化城市污水的效能,采用平行对比实验,考察了不同固体停留时间（t_SR）条件下反应器的有机物去除效率、生物絮凝效果、有机物回收效果和膜污染情况。结果表明：在t_SR分别为0.2、0.6、1.0 d时,HLB-MR反应器有机物去除效率均在85%以上,其出水化学需氧量（COD）质量浓度均保持在30 mg/L左右;反应器内的生物絮凝效果随着t_SR的延长而增强,其胶体COD絮凝效率从t_SR为0.2 d时的66%增加到t_SR为1.0 d时的95%,与此同时,有机物的矿化损失率也逐渐增加,从t_SR为0.2 d时的6.9%增加到t_SR为1.0 d时的10.5%,总COD的回收率逐渐降低;反应器内浓缩液的膜污染潜势随着t_SR的延长逐渐缓解,这与较长t_SR条件下反应器内胞外聚合物（EPS）产量较高、生物絮凝效果较好、微细颗粒（0~1 μm）的颗粒浓度较低有关。经过综合对比分析,0.6 d为反应器较优的t_SR参数,在该条件下,胶体COD的絮凝效率高达90%,膜污染程度较轻;总COD的矿化损失率低至7.4%,总COD的回收率（忽略膜清洗时有机物损失）可高达80%以上。     

中空纤维膜作生物膜载体无泡供氧处理污水研究

采用中空纤维膜作生物膜载体及无泡供氧装置,利用具有死端式和漂浮式特点的浸没式接触氧化工艺进行污水处理试验研究.结果表明:在控制系统工作压力0.03 MPa、污水中ρ(DO)为5～8 mg/L及HRT＝8h的条件下,污水中COD、BOD、SS的去除率分别达70%、90%和75%以上,NH3 -N、P的去除率也在70%以上.系统连续运行3个月,表现了较好的稳定性和抗有机负荷冲击能力.     

防渗膜渗漏偶极子检测的应用

偶极子法可用于防渗膜渗漏检测。膜上介质厚度以及偶极子与膜的距离会对偶极子检测的灵敏度产生影响。基于填埋场防渗膜高压直流电法的检测原理,对膜上介质厚度对偶极子检测的影响进行了研究,结果表明:防渗膜上介质厚度增大,通过在介质表面上移动偶极子来检测漏洞是困难的;但若偶极子能逼近膜的表面进行检测,无论膜上介质厚度多大,在漏洞附近都能检测到明显的电势异常。     

An efficient flexible membrane boundary condition for DEM simulation of axisymmetric element tests

The mechanical response of an assembly of particles depends on the applied boundary conditions. Robust calibration of numerical discrete systems to laboratory results is also a primary step in many studies of granular materials. In this study, a new membrane model was developed for simulating axisymmetric element tests. This membrane model uses a simple algorithm of an array of independently controlled walls and is computationally efficient. The effect of boundary flexibility on the system response was investigated by simulating a series of triaxial tests on dense and loose specimens. At the specimen scale, differences in shear strength and volume change of specimens were observed. It was shown that localization pattern depends on the applied boundary conditions. At the particle scale, particle‐membrane contact forces, coordination number, local void ratio, and anisotropy of fabric were all affected by the boundary flexibility.     

SEM Observation of the Wing Membrane of Beipiaopterus chenianus (Pterosauria)

The cross-section and surface structures of wing membranes from the ctenochasmatid pterosaur Beipiaopterus chenianus were observed through a scanning electron microscope （SEM）. The results show that the wing membrane contains a high density of blood vessels, implying strong thermoregulatory function, similar to that of a bat wing membrane. This is the first comparison of the microstmctures of pterosaur wing membranes with those of the modem bat. It is inferred that a bat-like physiology exists, at least in relatively small pterosaurs suggesting that these pterosaurs were warm-blooded, active fliers.     

高效液膜分离富集铜（Ⅱ）与测定微量铜

应用高效乱状液膜技术分离、富集水和土壤样品中微量铜。研究了流动载体（Ｐ２０４）、在面活性剂（Ｓｐａｎ８０）、膜的增强剂（液体石蜡）、膜溶剂（煤油）和内相解吸剂（２．５ｍｏｌ／ＬＨ２ＳＯ４）等液膜体系，对分离富集微量铜（Ⅱ）的影响。确定了Ｓｐａｎ８０－Ｐ２０４－液体石蜡－煤油－Ｈ２ＳＯ４高效液膜体系的最佳组成和最适宜的实验条件。富集后的溶液用１－（２－毗啶偶氮）－２一萘酚（ＰＡＮ）分光光度法测定铜（Ⅱ）。本法富集水和土壤中微量铜（Ⅱ），回收率在９９％以上。已成功地应用于测定水和土壤中的微量铜，相对标准偏差ＲＳＤ／％为１．２—４．５，结果十分满意。     

碳棒涂膜式PVC膜铯离子选择电极的研制和应用

本文作者研制成功以四苯硼铯为活性物质的碳棒涂膜式PVC膜铯离子选择性电极。电极最佳膜组成:四苯硼铯5mg,邻苯二甲酸二丁酯0.4ml,硝基苯0.2ml,PVC粉0.2g。电极性能优良,制作简单,操作方便。结合大粒度磷钼酸铵和结晶形锑酸分离K~+,Na~+,巳将此电极用于卤水样中铯的测定,结果令人满意。     

A rapid and direct method for organic nitrogen analysis in environment

Organic nitrogen is omnipresent in nature. The variations of dissolved organic nitrogen （DON） concentration are usually a result of microbial activity, anthropogenic influence, and/or other physical-chemical processes （e.g. photo-mineralization）. Therefore, DON serves as an important indicator for aquatic life cycles and water qualities. However, current DON detection methods inevitably produce exaggerated standard deviation, due to their inherent subtraction processes, as shown in the below equation. Consequently, they are incapable of propelling further understandings of the DON occurrence, DON role in nutrient recycling, and DON potential human toxicity as well. SDON=（STN2＋SDIN^2）0.5, where： S=standard deviation in an effort to overcome the barricade, the primary goal of this study is to develop a membrane pretreatrnent unit using electro-dialysis （EDI） process. Similar to the well-known mechanism used in dissolved organic carbon （DOC） analysis, which employs acidification and following purging to eliminate the inorganic carbon species, this study believes that EDI could significantly （〉99%） remove the dissolved inorganic nitrogen （DIN） species （i.e., ammonia, nitrite and nitrate） and concurrently retain most of organic nitrogen materials. By grafting the pretreatment unit with a total nitrogen （TN） analyzer, the system then enables direct detection of DON. Meanwhile, EDI discriminates nitrogen not only on size differences, but also on electrostatic force that separates nitrogen species according to their charge, thus making it more advantageous than other membrane technologies. Results showed that this approach was successfully used to separate inorganic from organic nitrogen for the selected water samples, including model amino acids, natural organic water ＆ isolates （i.e., humic substance）, and wastewater plant effluents. The EDI process was able to reduce more than 99% of inorganic nitrogen species within 2 hours under a 40-voltage operation condition, ending up with negligible DIN. Meanwhile, it retained more than 90% of organic matter （in terms of DOC） for natural water samples and 80% for wastewater effluent samples, meaning that DON can be analyzed directly without sacrifising significant organics. In addition, the EDI unit deleted other inorganic anions such as bicarbonate, chloride, sulfate, and phosphate, too, implying that this unit might also be applied to other organic matter like organic chloride, sulfur, phosphorous, etc.     

Transient Modeling of Hyperfiltration Effects

Transient models are needed to analyze time-dependent problems like hyperfiltration associated with head differences across clay barriers. Hyperfiltration (solute-sieving) effects create an increased concentration of natural groundwater solutes outside the clay barrier due to the inward head gradient. The purpose of our model is to predict solute buildup and distribution during hyperfiltration providing a basis for time analysis of solute migration. Required input parameters for the model include membrane properties like reflection coefficient, hydraulic conductivity, and solute concentration on the high-pressure side of the membrane before the onset of steady state, solution flux, and the effluent concentration. Model verification is based on published experimental results. The transient hyperfiltration model presented herein may prove useful in elucidating clay membrane (hyperfiltration) effects in the subsurface, however the sole purpose of this paper is to develop a transient model of hyperfiltration effects and test it by using published experimental data.     

Simulating the membrane contact patterns of triaxial sand specimens

One of the common sources of error in triaxial tests is the penetration of the latex membrane into the peripheral voids of the specimen as confining pressure is applied. Existing analytical solutions developed to predict the magnitude of this membrane penetration have all assumed that the peripheral sand particles in contact with the surrounding membrane are arranged so that the centroids of the sand–membrane contact areas form a square pattern of side length D₅₀ on a plane parallel to the undeflected membrane. Measurements made on digital images of sand–membrane contact patterns for triaxial specimens of varying characteristics have shown this assumption to be inadequate. The analysis presented herein shows how actual contact pattern can be reasonably replicated by simulated patterns. These simulated patterns are generated by adding randomly selected distances to the centroid co‐ordinates of contact areas initially placed in a systematic grid pattern. The results indicate that it is possible to systematically model sand–membrane contact patterns as a function of triaxial specimen characteristics such as relative density and preparation method. The ability to simulate the real patterns eliminates the reliance of existing analytical solutions on a single assumed square contact pattern and hence can serve as the basis for improving the accuracy of future solutions to account for the effects of membrane penetration. Copyright © 2000 John Wiley & Sons, Ltd.     

Modelling of membranes in the material point method with applications

The objective of this paper is to formulate and validate an accurate MPM approach for the numerical simulation of the large displacement of membranes containing soil. In the proposed approach, the membrane is discretised by a surface mesh that allows accurate simulation of membrane stresses. The membrane is free to move through a three‐dimensional grid for a continuum consisting of tetrahedral elements. The approach is applied to model a geocontainer being released from a split barge, taking into account the frictional contact between the geotextile and the barge. No‐slip contact is assumed between the geotextile and the soil inside. The effect of geocontainer interaction is investigated by dropping a second container. Copyright © 2014 John Wiley & Sons, Ltd.     

Application of membrane technology for water treatment： Ultrasound-associated cleaning of fouled microfiltration membranes

The use of membranes is a widely employed, versatile, and effective separation process. One of the limiting aspects in applying microfiltration （MF） for wastewater treatment is that of problems with membrane fouling and consequent flux reduction. Membrane fouling occurs by the irreversible deposition of retained particles, colloids, macromolecules, salts, etc. at the membrane surface and/or inside the membrane. The predominant fouling mechanisms observed with MF membranes are classified as three categories： the build-up of a cake layer on the membrane surface, blocking of membrane pores, and adsorption of fouling material on the membrane surface or in the pore walls. Although many techniques have been developed to overcome fouling, studies on membrane cleaning still seem to be insufficient for practical membrane filtration systems. Current membrane cleaning technologies include hydraulic, chemical, and mechanical methods. Ultrasound （US） has been widely used as a method of cleaning materials because of the cavitation phenomenon. In this study, US cleaning technique was applied to removing the fouling of polyvinglidenefluoride （PVDF） MF membrane, which was used to treat yeast cell and isolated soybean protein （ISP） solution, respectively. The US employed 40 kHz frequency and the output power of 1.43-2.85 W/cm^2. The evolution of the cleaning effect is followed by the measurements of the flux recovery rate （FRstat） and the cleaning time cycle. Results showed that the membrane property, which was fouled by yeast cell solution, could be recovered by water cleaning with US irradiation. And the cleaning time with the same FRstat decreased with the increase of US intensity.     

低浓度磷酸一酯的膜富集和气相色谱测定

磷酸一酯（ＲＯ）Ｐ（Ｏ）（ＯＨ）２是一种强极性的有机磷化合物。研究了水体中磷酸一（１－萘）酯的富集和上色谱分析,建立了一个简便快速、高灵敏度、实用的分析方法。富集是采用固相萃取方法,选用载有十八烷基硅烷的尼龙滤膜吸附,甲醇洗脱,回收率达７２％￣７％。它的气相色谱分析选用ＢＳＴＦＡ为衍生剂,反应条件为温度６５℃,反应时间３０ｍｉｎ,获得了满意的结果。方法的最低检测限为０。０６ｎｇ。