褶型纤维过滤介质压力损失的多尺寸模拟

统筹考虑纤维结构特性、纤维排布及纤维层数等因素,基于MATLAB编写控制程序,建立褶型纤维过滤介质微观尺寸模型,并计算过滤介质固体体积分数?,采用数值模拟方法获取微观尺寸下过滤风速v与压力损失Δp之间的数学关联式,进而获取介质的粘性阻力系数C1。在此基础上,建立褶型纤维过滤介质宏观尺寸模型,基于微观尺寸模拟得到的?及C1,采用数值模拟的方法得到宏观尺寸下迎面风速u与Δp之间的数学关联式,并将数学关联式与多个经验公式进行对比。结果表明,褶型纤维过滤介质内纤维排列方式及介质厚度对Δp有影响,但对C1等性质参数影响不大;微观尺寸研究得到的参数可以为宏观尺寸研究提供指导,微观结构与宏观结构性质参数可以沿用。本研究结果对拓展纤维过滤介质的研究方法及优化其结构具有重要理论及实际意义。     

双金属催化滤料生物滤池处理效果及对膜污染影响研究

双金属催化滤料生物滤池替代传统生物滤池,作为超滤膜系统的预处理工艺,可提高三氮的去除效率,保证产水水质稳定,显著减缓超滤膜污染,延长膜使用寿命。生物催化滤池内催化还原反应促进反硝化系统的进行,保证了水中硝酸氮和亚硝酸氮的分解去除;研究表明,生物催化滤池预处理较常规生物滤池可将TOC的去除率由73.2%提高到81.5%,其增加部分的主要成分为可引起膜污染的芳香蛋白类和富里酸类有机污染物。此外,双金属催化滤料增加了滤池的过滤精度,其出水胶体平均粒径明显小于常规生物滤池。催化还原反应产生的铁离子在过滤紊流的环境中微絮凝,进一步去除了微污染水源水中的胶体和悬浮物,减轻了胶体颗粒对超滤膜的污染。除具有常规滤池的生物降解、过滤作用外,双金属催化滤料生物滤池还具有催化还原和微絮凝的协同作用,显著提高了水中有机污染物和胶体颗粒的去除率,超滤膜污染得到有效减缓。     

Wettability studies of filter media using capillary rise test

Filtration process is a typical tertiary treatment method for oily wastewater, suitable for the lower oil concentration and oil-in-water emulsion system. Therein the wettability of oil-in-water emulsions to filter media probably has some significant influences on the oil removal efficiency, namely a lipophilic filter medium have a better performance in oil droplets coalescence and attachment than a hydrophilic one. In this paper, a Lipophilic to Hydrophilic Ratio (LHR) concept was defined on the basis of Washburn's equation and a test equipment was correspondingly designed, which were used to compare quantificationally the wettable selectivities of three filter media to oil and water. The selected filters were anthracite, manganese ore and quartz sand particles with a size fraction of +0.9 to 1.2 mm and the wetting liquids were apolar cyclohexane and polar deionized water. At the same time, the effect of filter particle size on the LHR value was also explored. Linear least-square fits for all wetting rates gave regression coefficients of more than 0.9991, confirming the suitability of the experimental method for filter particles and further validating Washburn's theory. The determined LHR values of anthracite, manganese ore and quartz sand are 1.93, 0.75 and 0.69, respectively, which means anthracite is lipophilic while manganese ore and quartz sand are hydrophilic. Moreover, for three selected particle size fractions the LHR values of anthracite particles are always the greatest and that of manganese ore are a little bit greater than quartz sand particles. Therefore, it can be deduced that the wettable differences probably be attributed to the differences of surface chemistries of filter samples. Namely, anthracite surface contains principally organic functional groups composed of carbon and oxygen elements and therefore presents apolar and lipophilic characterization, while manganese ore and quartz sand surfaces have SiO₂ species and make them polar and hydrophilic. This conclusion is approximatively confirmed by the analysis results of X-ray photoelectron spectroscopy (XPS).     

基于EKF和UKF算法非均匀介质热物性参数重建

将无迹卡尔曼滤波技术(unscented Kalman filter, UKF)用于求解一维介质热物性参数反演问题;也对利用扩展卡尔曼滤波技术(extended Kalman filter, EKF)反演一维介质中热导率问题进行了研究。首先给出了正问题模型,然后详细介绍了EKF算法和UKF算法的基本原理。最后为了验证当前算法的可行性,采用UKF算法重建了介质内部随位置变化的热导率,并采用EKF算法重建了介质内部随时间变化的热导率。计算结果表明,UKF算法和EKF算法均能较为准确地反演介质的热导率。为了减小重建结果的时间滞后,建议使用较小的测量误差协方差R。     

金属纤维滤料在水泥除尘领域的应用分析

水泥行业生产过程会产生大量的粉尘,最新大气污染物排放标准对水泥行业有了更加严格的要求。滤袋作为水泥厂袋式除尘器的核心部件,其运行的稳定性直接决定着除尘器排放是否达标。金属纤维滤料作为一种耐高温、强度高、透气量大的新型材料,完全满足当前水泥工业窑除尘的控制要求。     

Mass transfer modeling of membrane carrier system for extraction of Ce(IV) from sulfate media using hollow fiber supported liquid membrane

A theoretical and experimental study on the extraction and stripping of Ce(IV) ions from sulfate media using microporous hydrophobic hollow fiber supported liquid membrane has been performed. The experiments were made in the recycling mode. Tri-n-octylamine (TOA) was used as extractant diluted in kerosene and sodium hydroxide was use as strip solution. The mathematical model focused on the extraction side of a liquid membrane system. The aqueous feed mass transfer coefficient (k_i) and the organic mass transfer coefficient (k_m) which were calculated from the model were 9.47 X 10^-2 and 6.303 cm/s, respectively. Therefore, the rate controlling step is the diffusion of the cerium complex across a liquid membrane. In addition, the mass transfer modeling was performed and the validity of the developed model was evaluated with experimental data and found to tie in well with the theoretical value when the concentration of TOA was higher than 5% (v/v).     

液膜及膜萃取拆分手性物质的研究进展

随着人们对于单一手性物质尤其是手性药物需求的日益增长,手性物质的拆分技术成为热门的研究课题,其中液膜及膜萃取拆分技术作为一种低能耗和易于工业放大的手性拆分技术受到广泛的关注.着重介绍了用于对映体分离的支撑液膜、乳化液膜、厚体液膜、中空纤维膜等技术在手性物质分离方面的近期研究成果和应用开发现状,并总结了各种方法的优缺点.指出了中空纤维膜具有稳定性较好、传质面积大、传质高度低等优点,具有更大的工业应用前景,同时分析了手性物质膜萃取分离基础理论和技术的发展方向.     

Designing optimally-graded depth filter media using a novel multiscale method

Even though current manufacturing methods allow to build precisely-defined graded depth filter media, it remains unclear which local filtration properties are desirable. We, therefore, introduce a multiscale approach which links pore and continuum scale (PS and CS) to address this question. Based on data from PS simulations, local filtration performance, as described by the filter coefficient, is predicted on the CS by an optimal control solution and the obtained trajectory is translated back to the PS where it is validated. Two case studies are presented: a bidisperse fibrous medium and a granular depth filter composed of bidisperse particles. Both media are optimized to achieve a homogenous deposition of separated impurities along the filter depth. It is found that the presented method allows to reach this goal reasonably well in both cases. We claim that our method forms a good basis for further developments for which promising possibilities are highlighted.     

Comparison of the relative performance efficiencies of melt-blown and glass fiber filter media for managing fine particles

The purpose of this study was to compare the performance efficiency of melt-blown and currently used glass fiber filter media under the same environmental conditions. To evaluate filter efficiency, filter class was determined according to ISO and European standards (EN 1822-1:2009) using an automated filter tester (0.3 μm size), taking into account particle filtration, fractional efficiency for negative pressure devices, and consumption of electrical power. The average fractional efficiency, quality factor (QF), fractional efficiency by dust loading amount, pressure by dust loading amount, and QF by dust loading amount were higher in the case of melt-blown media than in the case of glass fiber filters. The fractional efficiency of hydrocharged melt-blown filters was higher than that of uncharged media. Based on performance efficiency, melt-blown filters are more effective high efficiency particulate air filters than glass fiber media.

Copyright © 2018 American Association for Aerosol Research     

微孔过滤介质的进展

近２０年来用于固液分离的普通过滤介质除用化纤织物几乎取代了天然织物过滤介质外，微孔过滤介质有了突破性进展，相继出现了亲水微孔陶瓷；微孔复合薄膜，以及单丝纤维过滤介质等，本文综合介绍它们的特性及其出现的背景和重要意义。     

高效纤维过滤器的优化

介绍了LLY-高效纤维过滤器的工作原理,分析了该设备存在的问题。针对过滤水质变差、过滤效率降低等问题,对设备进行了一些工艺上的改造,更改了设备内部的主要备件的材质,优化了滤料数量,改进了多孔板布孔方式和布气装置布孔方式,取得了良好的经济效益和社会效益。     

Cadmium removal using hollow fiber membrane with organic extradant

Removal of cadmium ion by using a hollow fiber module is investigated experimentally, and organic extradant is applied to enhance the removal rate. The roles of pH, flow rates of the aqueous phase and the organic phase, initial concentration of cadmium ion and coexisting metals are investigated to find an optimum operating condition of the module. The experimental outcome indicates that the best performance is yielded with pH of 4 and the flow rate of aqueous phase in tube side flow controls mass transfer rate. In addition, the initial concentration of 100 ppm gives the best removal. Effect of coexisting component is negligible except Zn and Cu when both of them are present at the same time.     

Development and evaluation of multilayer air filter media

Three types of multilayer air filter media were developed and evaluated. Two other existing filters were also used for comparison of filter performance. The pressure drop, the collection efficiency, and the dust-holding capacity of the tested filters were measured, and the internal structure of the filter media was analyzed by using a scanning electron microscope. The multilayer filters tested in this study are composed of pre-surface layer, surface layer, and substrate layer. Among those layers, the surface layer is mainly responsible for particle collection. As a test result, it was found that the thickness of a surface layer has the greatest effect on filtration performance of a multilayer air filter. Additionally, filtration velocity and electrostatic forces should be considered together as important parameters for multilayer air filter design.     

中空纤维膜法制备聚合氯化铝的研究

无机高分子絮凝剂聚合氯化铝(PAC)中的Alb形态质量分数是衡量其絮凝活性的主要指标。如何有效地制备高Alb质量分数的PAC产品已成为研究的重点。文中基于中空纤维膜表面具有大量的微米级微孔这一特点,采用中空纤维膜反应器作为碱液分布器制备PAC,实现了碱液微量连续可控地加入到AlCl3溶液中,从而显著提高了产品中的Alb质量分数。实验优化了制备工艺:碱化度B为2.0,碱液(NaOH)浓度为0.2 mol/L,氯化铝浓度为0.5 mol/L。检测结果表明:膜法制备的聚合氯化铝Alb质量分数可达90.18%,远高于其他方法制备的产品,其对染料模拟废水的絮凝效果远好于工业化产品。     

Performance of a compact submerged membrane sequencing batch reactor (SM-SBR) for greywater treatment

A long-term study was carried out to evaluate the performance of submerged membrane sequencing batch reactors (SM-SBR) for greywater treatment. Three pilot plants were operated in three different countries with distinct wastewaters to prove that treated greywater can be used for reuse purposes.In all plants the permeate quality fulfilled in most cases the high mandatory values of different European directives. Membrane permeability declined significantly within a period of three to four months so that recovery cleanings were necessary 3 to 4 times a year. In general, the treated greywater from an SM-SBR can be reused for irrigation or cleaning purposes. SM-SBR for greywater treatment are especially interesting in cases of space limitations where the small footprint of the system can outweigh inconveniences like frequent chemical cleanings.     

V型纤维滤池设计及运行

介绍了V型纤维束滤料滤池的工艺设计和运行.某污水厂现场试验表明,滤速为25 m/h时,截污容量为5.5 kg/m3,SS去除率为93.04%,CODCr去除率为27.6%.另外水头损失7.84×10-3 MPa,剩余积泥率≤0.5%～1%,自用水耗为周期制水量的1%左右,具有很高的经济运行性.     

Effect of intermittent back ozonation for membrane fouling reduction in microfiltration using a metal membrane

In a microfiltration system using a metal membrane for municipal raw sewage reclamation, the following research points were mainly investigated: 1) Effect of intermittent back ozonation for membrane fouling reduction, 2) effect of operational parameters for permeation flux, and 3) the estimation of optimal operational conditions using an empirical model in the case of back ozonation. Intermittent back ozonation dramatically improved the membrane fouling. The permeation flux was recovered up to 90% of initial flux with dosage of 0.27 (mgO₃/cm³/cycle). Among operational parameters, we found that ozone concentration was the most influential parameter for membrane fouling reduction. In the case of back ozonation, the optimal values of each operational parameter with respect to ozone concentration, ozone gas flow rate and injection time to satisfy 90% recovery of initial flux were 20.2 (mgO₃/L), 3.1 (L/min) and 2.1 (min), respectively. Intermittent back ozonation is believed to be an innovative and feasible technology for fouling reduction and high permeation flux in case inorganic membrane material is being used.