平板膜生物反应器适宜运行通量与临界通量关系

通过考察平板膜生物反应器以不同初始启动通量恒流运行后的膜污染情况．研究系统适且运行通量与临界通量间的关系。结果表明，该膜生物反应器的临界通量为40-43L（m2-h）。以不同通量恒流运行后膜污染状况可分为3种情况：初始启动通量不小于临界通量时，短时间内膜污染急剧发展：初始启动通量位于临界通量的2，5．4／5时。开始阶段膜污染缓慢发展，但在运行一段时间后膜污染都进入迅速发展阶段；初始启动通量小于临界通量的2／5时，在近4个月的试验期间内系统维持稳定运行。结合膜面区域污染程度的不均匀性及实际运行过程中临界通量的变化．在冬季低温情况下，适宜的运行通量为2／5-1，2的初始临界通量值。     

正渗透膜有机污染的实验研究

选择海藻酸钠、牛血清白蛋白和单宁酸作特征污染物,研究了错流过滤的正渗透膜系统处理水中有机物时,通量的变化和污染物在正渗透膜沉积的关系,在没有有机物的空白实验中,初始的水通量为8.42 L/(m2·h),所有的通量都除以初始通量来进行标准化。结果表明,不同污染物对通量的影响差别很大,海藻酸钠的加入极大地影响了通量的变化,然而牛血清白蛋白和单宁酸对通量的影响非常轻微。实验还通过扫描式电子显微镜和傅立叶红外光谱仪对污染后的正渗透膜进行了表征,在膜表面发现了大量的海藻酸钠,说明其引起的膜污染很严重,相比之下,牛血清白蛋白和单宁酸的污染却很不明显。同时对污染后的正渗透膜进行了洗脱,测量了洗脱液的总有机碳(TOC),结果相同。     

超滤膜在饮用水处理中临界通量的影响因素研究

超滤膜在临界通量以下过滤可不产生膜污染或产生极轻的膜污染,针对超滤膜在饮用水处理中的临界通量的影响因素,系统考察曝气、过滤方式和混凝沉淀预处理等对浸没式超滤膜处理松花江水临界通量的影响.结果表明,曝气强度达到10 m3/(m2·h),连续曝气可将超滤膜的临界通量提高5 L/(m2·h),曝气强度达到40 m3/(m2·...     

正渗透净水过程中三醋酸纤维素膜表面特性研究

以浓缩天然水作为模型污染物,研究了正渗透(FO)系统错流过滤水中有机物时,不同温度和错流速度下膜通量的变化;通过对被污染的膜进行接触角和红外光谱分析,考察污染物在FO膜的沉积规律以及对膜表面特性造成的影响。结果表明,温度越高以及错流速度越小,膜污染越强,膜通量下降越大。膜上污染物以亲水性物质为主,膜污染物降低了膜的接触角。污染物在波数为1 408 cm-1和871 cm-1处有强特征峰,说明天然水中氨基酸是膜可能的主要污染物。     

正渗透膜污染影响因素的研究与分析

以海藻酸钠（ALG）为典型有机污染物,采用TFC FO膜,以水通量下降率和污染阻力作为膜污染的评价指标,探究了正渗透（FO）过程中的膜摆向（FO模式和PRO模式）、原料液（FS）和驱动液（DS）的浓度、原料液中Ca²⁺浓度和pH对FO膜污染的影响规律,并提出适宜的膜清洗方案。结果表明,在PRO模式下,膜污染阻力为3.38×10¹¹m^-1,而在FO模式下仅为3.88×10¹⁰m^-1,表明FO模式污染轻;FS或者DS浓度的增大均会导致污染阻力增大,使得污染更加严重;当FS中不含Ca²⁺和含Ca²⁺浓度分别为1mmol/L和2mmol/L时,相较于初始通量,其通量降低率分别15.40%、18.49%和24.93%,当Ca²⁺浓度从1mmol/L增大到2mmol/L过程中,膜污染阻力增大1.6倍;当FS的pH为4.2、7.0和10.7时,水通量降低率依次增加,分别为14.56%、14.82%和18.78%。分别采用去离子水、pH为3.0的HCl溶液、pH为11.8的NaOH溶液以及十二烷基硫酸钠（SDS,pH=11.0）溶液对膜进行清洗,得到SDS溶液清洗效果较好,通量恢复率可达90.70%。     

平板膜污泥浓缩临界通量与膜渗透性能研究

研究了不同浸泡条件、污泥含量、曝气量和膜龄对平板膜污泥浓缩( MST)临界通量和膜渗透性的影响,并通过环境扫描电镜检测分析长期运行平板膜的表面损伤情况.结果显示,良好贮存条件及低污泥含量的操作条件有助于提升临界膜通量与起始膜渗透性;曝气量升高,膜渗透性提升且稳定性增强;随着膜龄增加,膜渗透性能变差;无机颗粒摩擦与清洗会增加平板膜表面粗糙度,降低膜渗透性能,NaClO清洗对膜面损伤甚为严重.     

正渗透膜分离糖类有机物的影响因素研究

实验以蔗糖等中性亲水小分子有机物作为模型污染物,考察了汲取液浓度、分子量、膜朝向等因素对正渗透分离糖类有机物的影响.结果表明,蔗糖等糖类有机物能被正渗透膜有效截留.4mol/L的较高浓度汲取液导致通量明显下降.当膜活性层朝向汲取液时,增大糖类的分子量(1 000Da)导致膜通量降低,而膜截留率为91.2％.水通量产生的...     

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。     

纳米材料用于薄层复合正渗透膜的制备

正渗透是一种以渗透压为驱动力的膜分离技术,它具有低污染、低能耗、在常温常压下运行等优点,因而被广泛地应用于水处理和脱盐。然而,正渗透技术依然存在一些瓶颈,包括浓差极化现象、膜污染、溶质的反向扩散和新的膜材料以及汲取液的设计。纳米材料的快速发展为解决这些问题提供了一种有效的途径,将无机纳米材料作为填料,添加到薄层复合(TFC)膜中能够有效地增正渗透性能。这篇综述概括了纳米无机材料作为填料用于薄层复合正渗透膜的制备。     

膜生物反应器处理生活污水临界通量的研究

利用“通量阶式递增法”对临界通量进行了测定,得出MBR的3个水动力学操作区:超临界区、临界区和次临界区;在MLSS的质量浓度为6 000 mg/L、曝气量为0.5 m3/h的条件下,膜组件的临界通量区域为10.68～13.86 L/(m2.h),据此确定组件的次临界通量为12 L/(m2.h)。在此基础上研究了次临界通量下的运行特性,试验表明,次临界通量下的膜污染过程具有明显的两阶段特征:第一阶段的TMP呈平缓直线上升,第二阶段的TMP呈剧烈直线上升。     

Fouling and cleaning of polymer-entwined graphene oxide nanocomposite membrane for forward osmosis process

In this study, we have characterized membrane fouling of polymer-entwined graphene oxide membranes with a simulated feed solution containing organic foulants for wastewater treatment applications, as well as with a simulated inorganic wastewater with high iron and silicon concentrations relevant to steel industry wastewater reclamation. Membrane cleaning processes by cross-flow surface flushing with water were then applied to demonstrate water flux recovery for long-term application. Salt rejection property was retained constant during fouling process, whereas water flux was found to be reduced continuously due to fouling but was readily recoverable following surface flushing.     

A review on the forward osmosis applications and fouling control strategies for wastewater treatment

During the last decades, the utilization of osmotic pressure-driven forward osmosis technology for wastewater treatment has drawn great interest, due to its high separation efficiency, low membrane fouling propensity, high water recovery and relatively low energy consumption. This review paper summarizes the implementation of forward osmosis technology for various wastewater treatment including municipal sewage, landfill leachate, oil/gas exploitation wastewater, textile wastewater, mine wastewater, and radioactive wastewater. However, membrane fouling is still a critical issue, which affects water flux stability, membrane life and operating cost. Different membrane fouling types and corresponding fouling mechanisms, including organic fouling, inorganic fouling, biofouling and combined fouling are therefore further discussed. The fouling control strategies including feed pre-treatment, operation condition optimization, membrane selection and modification, membrane cleaning and tailoring the chemistry of draw solution are also reviewed comprehensively. At the end of paper, some recommendations are proposed.     

正渗透过程中水与溶质的传递现象

正渗透是一种利用渗透原理的新兴膜技术,近年来在国内外受到了广泛的关注。解析该过程中溶剂水的传递和驱动溶质的反向传递对其发展和应用至为关键。首先开展了两种膜的取向下,正渗透过程中的水通量和溶质反向摩尔通量的实验研究。当驱动溶液在膜分离层侧时,水通量更高,而溶质反向摩尔通量更低,表明水的传递对溶质的反向传递有限制作用。而后分别考察了不同的单一溶质和二元混合溶质作为驱动溶质时,水和溶质的传递现象。当单一中性溶质或电解质作为驱动溶质时,水通量和溶质反向摩尔通量均随驱动溶液浓度的升高而增大;在相同操作条件下,驱动溶质的扩散系数越小,溶质反向摩尔通量越小;中性溶质与电解质混合溶液为驱动溶液时,溶质分子之间存在耦合传递效应。     

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     

正渗透膜材料的研究进展

正渗透技术因其低能耗、耐污染等优势受到国际和国内众多学者的关注,尤其近几年来,取得了迅速发展。本文对正渗透过程中的影响因素以及浓差极化现象作了简要分析,结果表明,内浓差极化是影响正渗透技术效率低下的重要因素,而制备适当的膜材料是有效改善内浓差极化的关键技术。回顾了正渗透分离技术在国内外的发展历程,通过不懈的探索和研发,先后成功制备得到不同材料和结构的正渗透膜。重点讲述膜材料在正渗透领域所取得的最新研究进展,最后指出众多正渗透膜材料由于条件限制难以推广应用,希望在未来的研究过程中突破这项技术难题,缩短科研理论与实际应用之间的差距,在膜材料的实际应用方面取得创新性成果。     

正渗透技术在海水淡化中的应用

论述了正渗透技术的工作原理及其在海水淡化应用过程中的技术特点和主要问题,指出了正渗透膜材料和汲取液是未来研究的重点,并对正渗透技术未来的发展前景进行了展望。     

Feasibility of using polycarbonate as a substrate of thin film composite membrane in forward osmosis

In the present study, thin film composite (TFC) forward osmosis (FO) membranes with polycarbonate (PC (and polyether sulfone (PES) as substrates were fabricated to investigate the impact of the structural parameters of substrate on the performance of the membranes. Firstly, the substrates were prepared by Loeb-Sourirajan method. Characterization techniques including FESEM, contact angle measurement, pure water flux, gas permeability test, and tensile test were applied to investigate the properties of the substrates. After preparing suitable substrates, active layers were fabricated via interfacial polymerization (IP) technique. The performance and characterization test showed that PC is a relatively hydrophilic polymer with a good property for using as a substrate of FO TFC membrane but as the result of gas permeability test show, this membrane has large surface pore size in comparison with PES membrane. Mean pore size of PC and PES membrane is 378 and 139 nm, respectively. Also, the results show that the effective surface porosity of PC (285, 1/m) is more than PES (213, 1/m) substrate.