错流膜分离强化技术的理论分析

本文通过对一般高剪切错流膜分离强化方式和简谐运动错流膜分离强化方式所产生的流场进行分析，从错流膜分离的抗污染机理入手，对比了这两种错流膜分离强化方式的流场特性，能量消耗方式，分析出作者所提出的简谐运动错流膜分离强化方式较一般高剪切错流膜分离强化方式优越。     

电场促进膜过滤技术研究进展

分离过程中常用的膜过滤多以错流方式进行,但是滤面的附着物和浓度极化会使过滤速度大大降低,研究表明电场能够促进过滤的进行。简要介绍了电场促进过滤的概念及原理,综述了国内外对含胶体或蛋白质等难溶物质的介质进行电场促进膜过滤方面所进行的理论和实验研究,重点是外加电场的方式、大小、脉冲电压的频率等因素对过滤速度的影响。     

错流微滤过程的无因次特征量

从近膜面微粒的受力分析出发,对错流微滤过程进行了因次分析,得到新的特征量Rem和Eum,合理地概括了重要过程参数对微粒在膜面沉积的复合作用。由基于Eum和Rem数学模型所得的预测值与实验值高度吻合,说明用Eum和Rem表征复杂的错流微滤过程的合理性。     

高分子膜错流超滤过程的有限元分析

利用Navier-Stokes方程和连续性方程描述错流超滤自由流动区域的流场,与Darcy定律描述的膜介质中的流场相耦合,结合对流扩散方程以及吸附动态方程建立了高分子超滤膜污染过程的数学模型。针对实验中难以测试的吸附速率系数和解吸速率系数,结合文献中的结果进行了数据拟合,建立了计算式,并得到了很好的验证。采用有限元模拟方法分析了不同入口速率下高分子超滤膜的跨膜压力、沉积量和渗透通量沿管道长度方向的变化情况,有助于错流超滤工艺过程的优化设计。     

正渗透膜生物反应器膜过滤特性研究

以氯化钠为驱动溶质,采用正渗透膜生物反应器处理模拟生活污水,系统地考察了各因素对正渗透膜过滤性能的影响。结果表明,随着驱动液浓度增加,水通量和反向盐通量也随之增加;正渗透膜活性层朝向驱动液时(AL-DS)的水通量和反向盐通量较活性层朝向原料液(AL-FS)时大;水通量和反向盐通量与错流速率正相关,在错流速率较低时增加不明显;随着活性污泥浓度增加,水通量呈下降趋势,而反向盐通量呈上升趋势。     

错流速度对外置式MBR处理生活污水的影响

采用外置式管式膜生物反应器处理模拟生活污水,研究了系统对COD、NH4+-N和浊度去除状况,考察了错流速度对污染物去除效果及膜污染影响.结果表明,COD和NH4+-N去除率均达93％以上,且错流速度对系统出水水质影响较小,但较高的错流速度容易使出水浊度增加.错流速度由0.56m/s增至2.20m/s,膜污染周期由10d...     

动态膜在错流微滤系统中的应用

利用6000目的高岭土作为动态膜涂膜材料,在相同的条件下过滤活性污泥和二级出水.实验结果显示,动态膜过滤在出水水质和通量方面明显优于直接过滤,而处理二级出水在膜通量方面没有优势.清洗实验结果表明动态膜能有效降低膜内部污染,并能恢复到新膜通量的90%.污泥浓度越大,通量越小.提高膜面流速和增加压力都能有效的提高膜通量,但提高膜面流速更经济.     

酶膜反应器在生化领域的应用及其电场强化的研究

概述了酶膜反应器的理论研究和应用现状 ,比较酶膜反应器与传统反应器的特点和优势。重点介绍了酶膜反应在生化领域的应用情况及其效能 ,指出了酶膜反应器在应用中所面临的制约因素。同时 ,对电场强化酶膜反应器的机理及其研究及应用情况进行了叙述 ,并讨论了提高酶膜反应器效能的途径。     

生物除磷的电场强化作用及其规律研究

本课题通过对比试验对生物除磷的电场强化作用及其规律进行了初步研究,结果表明,在试验条件下(电流密度:i=0．04-0．08mA／cm2),无论那个反应时段(厌氧段、好氧段)施加电场,对提高、稳定生物除磷效率都有积极的作用;对比研究发现,在相同的电流密度下,好氧段电场强化对除磷效果的促进作用更明显,在最佳工况(好氧段强化,i=0．08mA／cm2),电场强化反应器TP平均去除率高达92％,比对照组普通生物反应器高出15％。另外,试验分析了剩余污泥的含磷量,数据显示,电场强化生物反应器剩余污泥含磷率达5．04％(干重),比对照组普通生物反应器高0．68％,进一步表明了电场可强化活性污泥的超量吸磷能力。     

Fouling mitigation in crossflow filtration using chaotic advection: A numerical study

Fouling mitigation in a crossflow filtration system using chaotic advection is numerically studied. A barrier-embedded partitioned pipe mixer (BPPM) is selected as a static mixer, creating chaotic advection in a laminar flow regime. Mixing characteristics are controlled via two design parameters, the mixing protocol and the dimensionless barrier height (β). The average dimensionless concentration boundary layer thickness () and the surface-averaged dimensionless wall concentration () dramatically decrease with the introduction of the BPPM, incorporating a chaotic flow system. and decrease as β increases, and the largest reduction of is observed in the counter-rotational protocol. A semi-ring configuration is revealed to be the most appropriate configuration to characterize mixing near the membrane surface. It is found that a filtration system with a globally chaotic flow shows the best mixing performance and the largest reduction of fouling.     

磁絮凝膜过滤工艺中附加磁场强化清洗

基于磁强化絮凝膜过滤(MEFMF)工艺中磁絮体和含磁滤饼层的特性,设计了在线(on-line)和离线(off-line)磁强化清洗(MEC)工艺.在磁场和曝气剪切的协同作用下,含磁滤饼层脱离膜纤维表面,膜通量恢复率较常规物理清洗(RC)明显提高.在离线磁强化清洗时,设计反洗装置中心的磁感应强度为6 mT,曝气强度为500 L·m^-2·min^-1,控制清洗时间为5 min,维持反洗压力0.04 MPa,可达到最佳的膜清洗效果,通量恢复率达97%以上.在外加磁场强化清洗过程中,滤饼层中的磁种发生磁化作用,滤饼层表现出微弱的宏观磁性,在磁场的作用下向磁极运动,使得膜通量恢复率明显提高.此外,在MEFMF工艺中采用间歇磁强化清洗,可以更加有效地去除引起不可逆膜污染的胶体和有机物,降低膜污染速率,减缓膜污染.     

Characterization of particle deposition during crossflow filtration as influenced by permeate flux and crossflow velocity using a microfluidic filtration system

Particle deposition during crossflow filtration is significantly influenced by the operating conditions, in particular the permeate flux and crossflow velocity. However, there is a lack of detailed knowledge about how deposit layer structures and distributions depend on operating parameters. This study uses a microfluidic visualisation filtration system to examine the influence of operating conditions on the deposition process during crossflow ultrafiltration from a microscopic perspective. Increasing the permeate flux caused an increasing amount of deposition and a thicker deposit layer. Higher crossflow velocities reduced the extent of deposition. The degree of deposition varied over a range of operating conditions due to the altered hydrodynamic forces exerted on the particles, which can be examined by the deposition probability according to an existing model. Building on this, an empirical correlation between the deposition probability and volume of deposition as a function of filtration time was developed, which gave good agreement with experimental results. The effect of solution conditions was also involved in this correlation as a interaction energies. This could be useful for predicting the dynamic deposition process during crossflow filtration over a range of operating and solution conditions.     

不同电极间距下自生电场膜生物反应器中的膜污染行为分析

以自制铜纳米线（Cu-NWs）导电微滤膜为膜组件兼阴极,构建自生电场膜生物反应器（SEF-MBR）,研究不同电极间距下自生电场强度、跨膜压差（TMP）与膜污染行为的变化规律,可为MBR技术升级及进一步推广应用提供理论依据。结果表明,当电极间距从4cm减小到2cm时,自生电场强度从0.7mV/cm提高到1.2mV/cm,TMP的上升速度从0.15kPa/d降低到0.08kPa/d。缩短电极间距有利于缓解膜污染。随电极间距减小,静电斥力提高了40.5%,阴极产生的H₂O₂和·OH浓度也大大增加。电极间距对SEF-MBRs好氧活性污泥的胞外聚合物含量影响不大,但均低于对照MBR系统。共聚焦激光扫描电镜（CLSM）观察发现,与对照系统相比,导电微滤膜表面的污染层厚度减小了20.2%,膜表面污染物以微生物总细胞和β-D-glucopyranose多糖为主。缩短电极间距可提高系统自生电场强度,进而提高静电斥力及H₂O₂和·OH产生量,减缓膜污染。     

陶瓷膜构型对错流微滤酵母悬浮液性能的影响

采用3种构型的陶瓷微滤膜元件对酵母悬浮液进行错流过滤实验,考察陶瓷膜元件的构型对于其错流过滤性能的影响。结果表明:减小陶瓷膜元件的通道直径可以提高料液在膜表面的剪切力,有助于提高过滤稳定通量和临界压力,在3 m/s膜面流速、0.1 MPa跨膜压差条件下,单管、19通道、55通道的稳定通量分别为96、128、196 L/(m2.h);在3 m/s膜面流速条件下,3种陶瓷膜元件的临界压力分别约为0.15、0.2、0.2 MPa。另外,减小通道直径还可以减小滤饼层的比阻,有利于降低过滤阻力;与提高膜面流速来增大过滤通量的方法相比,减小陶瓷膜的通道直径具有能耗较小的优点。     

陶瓷膜处理聚醚废水通量影响因素的试验研究

利用陶瓷膜技术处理高浓度聚醚废水回收大分子聚醚多元醇.研究了浓缩倍数、温度、跨膜压差(TMP)等因素对渗透通量的影响.通过对试验数据的统计学分析,确定TMP为0.20MPa、系统温度控制在43℃,此时CODCr的去除率＞95%,达到了设计要求.并对膜清洗工序进行了改进,提出了NaOH/EDTA复合清洗法,缩短了清洗时间.     

Factors influencing critical flux in membrane filtration of activated sludge

Membrane filtration of biomass is usually accompanied by significant flux decline due to cake‐layer formation and fouling. Crossflow filtration with flux controlled by pumping the permeate can produce stable fluxes if a ‘critical flux’ is not exceeded. Below critical flux the transmembrane pressure is typically very low and increases linearly with imposed flux. Above the critical flux the transmembrane pressure rises rapidly signifying cake‐layer formation which is usually accompanied by a continued rise in transmembrane pressure and/or a drop in delivered flux. A range of microfiltration and ultrafiltration membranes with pore sizes from 0.22 to 0.65 µm and molecular weight cut‐off of 100 kDa was used. The feed was an activated sludge mixed liquor with concentration in the range of 3–10 g dm⁻³. The results show that the critical flux depends on feed concentration and crossflow velocity, being higher for higher crossflow velocity or lower feed concentration. Critical flux was also dependent on membrane type, being lower for hydrophobic membranes. Although the transmembrane pressure was higher for the larger pore size membrane, no significant difference in critical flux was observed among different pore size membranes. © 1999 Society of Chemical Industry     

振动剪切强化膜过滤技术研究进展

综述了振动剪切强化膜过滤技术的组件形式、膜面剪切率的表征与计算、国内外研究等方面的进展情况。分析了该技术的优缺点。指出陶瓷膜的应用与新型组件的开发可能解决该技术所面临的问题,促进振动剪切强化膜过滤装备的开发与工业化应用的发展,并建议我国加强剪切强化膜过滤技术的研究和装备开发。     

膜处理乳化液废水过程中强化过滤的物理化学技术

传统膜技术在处理乳化液的过程中由于膜污染和浓差极化会导致通量迅速下降,故如何强化膜过滤、提高膜通量直接决定了膜组件的处理能力和运行成本。介绍了各种强化乳化液膜过滤处理的物理化学强化技术,阐述了技术原理和优缺点,同时提出了乳化液废水处理的高效集成工艺。