反渗透膜污堵原因分析及解决措施

某电厂反渗透系统运行中出现压力偏高、出力偏低以及清洗频繁等问题,对反渗透膜片的ICP、SEMEDX以及GC-MS等分析结果表明,有机污堵是造成反渗透系统故障的主要原因。采用NaOH、EDTA和SDS对膜片进行静态清洗试验,结果表明,EDTA碱洗对反渗透有机污堵清洗效果最好。采用EDTA碱洗和酸洗相结合的清洗方案对工程设备进行清洗后,反渗透运行压力和产水量基本恢复至初始状态。此外,结合电厂的实际运行情况,对水处理系统提出了运行优化方案。     

反渗透膜污染及其清洗的研究

反渗透膜分离技术在水处理中的应用越来越广泛,膜污染也日益受到重视。就常见的膜污染情况进行研究,针对不同的污染情况提出了几种常用的清洗方式,并比较了几种清洗方式的优劣,重点揭示了化学清洗机理,为反渗透膜的清洗提供建议。     

反渗透技术在钢铁工业废水处理和回用中的应用

针对原水水质情况和环保要求,确定采用反渗透膜技术处理该废水,介绍了系统工艺流程及主要设备,详细说明了反渗透膜技术处理钢铁工业废水的应用经验及效果。通过观察电导、产水量、压差的变化,分析了膜污染的成因,提出了清洗方案,并对反渗透系统的运行管理问题进行了论述。结果表明,酸-碱-酸的清洗方案对反渗透膜污染具有很好的控制效果。     

电厂反渗透系统膜污染防治与膜清洗的研究

考察了长期运行的电厂反渗透系统中导致膜污染的原因、膜污染的种类和膜的清洗方法。采用反渗透系统进水和浓水的水质分析数据,提出了判断膜污染原因及污染物组成。根据反渗透系统进水和浓水的水质分析数据,实验筛选了膜清洗剂配方。结果表明表面活性剂对无机、有机混合垢有明显的促溶作用,以0.05%Na-SDS＋0.1%NaOH＋1%Na4-EDTA为配方的清洗剂,其清洗无机、有机混合膜污染的效果良好。     

A pilot study for wastewater reclamation and reuse with MBR/RO and MF/RO systems

A pilot study was conducted to evaluate the quality of the effluent of an enhanced tertiary treatment process consisting of MBR/RO or MF/RO units and explore the feasibility of reclamation of treated effluent for potable and non-potable reuse applications. The performance of both the MBR/RO and MF/RO pilot plants was excellent. The MBR or MF alone was able to bring down the concentrations of most of the pollutants under acceptable limits for non-potable reuse applications. The application of RO further improved the treated water quality, especially the aesthetical and microbial qualities. Different strategies were employed to control membrane fouling in RO, and hypochlorite dosing showed the best results. The RO permeate quality in terms of conductivity, turbidity, organic content, ammonia, nitrate, hardness, E. coli and virus could meet the water quality requirements for many potable and non-potable reuse applications. In removal of total estrogens, the MBR/RO combination performed better than that of MF with RO, indicating the importance of the role of biomass. The rejection of virus in MBR and MF was greatly affected by the chemical membrane cleaning. It took more than 24 h for the recovery, implying that the presence of membrane biofilm plays a key role in rejection of virus.     

矿井水脱盐过程中卷式反渗透膜性能的数值模拟研究

为了更好地研究矿井水中无机盐组分对于反渗透过程产水、结垢及脱盐效果的影响,以内蒙古某煤矿矿井水水质组分作为进水水质条件,采用计算流体力学（CFD）模拟单支商用标准8寸卷式反渗透膜元件（陶氏BW30-400）内部的传质以及局部浓差极化的分布,预测实际运行情况下微溶盐结垢的风险。进水通道采用以阿基米德螺旋曲线为卷制轨迹的几何模型。无机盐的混盐作用通过混盐渗透压模型模拟。从全尺度卷式反渗透膜元件的模拟结果可以看出,卷式反渗透膜内的水流主要以轴向流速为主,沿切向阿基米德螺旋线的流速较低,对整体盐度分布的影响较小（<1%）,可以忽略不计,在后续模拟中采用简化模拟单元或几何模型或网格。在模拟操作条件下,卷式膜元件的浓水网产生的水头损失占整体水头损失约86%,为卷式膜元件中的主要水头损失来源。在没有安装浓水网的进水流道中最高Na₂SO₄浓度位于元件浓水出口处,高达3594 mg/L,约为有浓水网情况下的1.8倍。而且有浓水网的进水流道内,浓差极化现象主要发生在浓水网背水侧局部区域,影响范围较小。该模型模拟得到的产水量与实测产水量做对比,误差小于5%,同时模拟结果也接近ROSA9.1模拟数据（误差<4.4%）,因此可以对卷式反渗透膜的无机盐脱盐过程进行较精确的模拟仿真。与商业设计软件如ROSA（反渗透系统分析）相比,其只提供产水和浓水中的盐浓度信息,本文开发的模型可以提供浓度极化的特征信息,加深了对卷式反渗透膜在不同位置的潜在结垢风险的理解。     

RO and NF membrane fouling and cleaning and pore size distribution variations

The variations of porosity parameters of some reverse osmosis (RO) and nanofiltration (NF) polyamide thin-film composite membranes were determined in order to explain the changes of membranes' performances caused by membrane fouling and chemical cleaning of the fouled membranes. The pore size distribution curves and the effective number of pores in the membrane surface indicated plugging of the tight network pores in the membrane surface and even their disappearance during fouling. The enlargement of the wider aggregate pores was responsible for the noticed reduction in salt rejection. The initial pore structure of the fouled RO membrane was restored by immediate chemical cleaning. A delay of chemical cleaning of the fouled membranes led to irreversible changes in the porous structure of both the RO and NF membranes, which were caused by a microbial activity.     

Analysis of hollow fiber reverse osmosis membrane module of axial flow type

Several analyses of hollow fiber reverse osmosis (RO) modules in which permeate water flows from the outer to the inner side of the membrane have been attempted over the past 20 years. In our previous work, an FCP (Friction Concentration Polarization) model showed good agreement with a wide range of actual performance data of a hollow fiber RO membrane module of radial flow type. In this work, this analytical model was applied to axial flow type hollow fiber modules. The performance of the axial flow type module with high packing density of hollow fibers was analyzed, taking into consideration the axial concentration profile in the module. It was confirmed that this model showed good agreement with experimental data for an axial flow type RO membrane module. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

废旧反渗透膜循环再利用研究现状与进展

随着反渗透（RO）技术在水处理领域的广泛应用,全球每年有数百万计的废旧RO膜组件作为垃圾被处理处置,由此造成了环境污染与资源浪费。本文首先综述了废旧RO膜可能的循环再利用方案和相关的应用案例,为了比较不同循环方式对环境的影响,概述了通过全生命周期分析（LCA）的方法评价不同循环利用方式的环境效益和物质投入的研究进展。文章指出研究结果表明：回收利用废旧RO膜是研究RO膜末端处理的方法之一,其中包括通过使用清洗后的RO膜作为新生RO膜直接再利用、通过化学转化为其他多孔膜材料再循环使用、通过清洗RO膜拆解回收RO膜。另外,LCA在膜工艺中的分析仍以评估使用过程为主,而缺少在膜设计、膜改造和膜回收等关键过程的分析研究。     

Critical risk points of nanofiltration and reverse osmosis processes in water recycling applications

NF/RO membrane filtration processes have been recognized as an important technology to facilitate water recycling. Those processes are well-proven technologies, which can be used to remove a wide range of contaminants including trace contaminants that are of particular concern in water recycling. However, risk implications in association with brine or concentrate and membrane cleaning wastewater disposal have to date not been adequately understood. This study examines the adsorption and release process of several endocrine-disrupting chemicals (EDCs) during NF/RO filtration processes. Results reported here indicate that the membrane can serve as a large reservoir for EDCs and their release may be possible during membrane cleaning or erratic pH variation during operation. Treatment of membrane cleaning solution should be carefully considered when EDCs are amongst the target contaminants in NF/RO membrane filtration.     

正渗透策略和化学清洗海水淡化反渗透膜

为解决海水淡化过程中反渗透膜的污染问题,研究了基于正渗透策略的反渗透产水、模拟反渗透浓水、模拟海水不同的组合清洗和清洗时间对膜通量和截留率的影响。针对不可逆污染,研究了不同化学清洗药剂、浸泡时间、浓度对膜通量和截留率的影响。结果表明,正渗透策略清洗方式中,淡水/模拟反渗透浓水的组合清洗方式效果最佳,其归一化通量从9.48 L/(m²·h·MPa)提升至13.6 L/(m²·h·MPa),截留率从80.59%提升至92.80%。此外,经质量分数为2%的柠檬酸溶液浸泡2 h后,再使用质量分数为1%的乙二胺四乙酸四钠盐和0.3%的三聚磷酸钠溶液浸泡1.5 h,其归一化通量从9.48 L/(m²·h·MPa)提升至14.3 L/(m²·h·MPa),截留率从80.59%提升至96.27%。从SEM和AFM图可以看出,正渗透清洗策略并未对膜表面选择层造成损坏,且可以清洗膜表面的有机污染物和无机污染物,因此,应用这种方法对污染的反渗透膜进行清洗,可延长化学清洗周期,减少化学清洗剂用量,具有一定的工业应用前景。     

Forward-osmosis strategy and chemical cleaning of seawater desalination reverse osmosis membranes

In order to settle the membrane fouling of reverse osmosis membranes in seawater desalination process, this study reported a novel strategy based on forward-osmosis process and discussed the effects of different factors like different cleaning combination among reverse osmosis product, simulated reverse osmosis concentrate and simulated seawater, as well as cleaning time on the membrane permeate flux and salt rejection. For irreversible fouling, the effects of different chemical cleaning agents, immersion time and concentration were also investigated in this study. The results exhibited that the cleaning combination between diluted water and simulated reverse osmosis concentrate possessed the best cleaning performance in the process of forward-osmosis cleaning. Such approach also enhanced normalized flux from 9.48 L/(m²·h·MPa) to 13.6 L/(m²·h·MPa) and enhanced NaCl rejection from 80.59% to 92.80%. Furthermore, the normalized flux was enhanced from 9.48 L/(m²·h·MPa) to 14.3 L/(m²·h·MPa) and NaCl rejection was also enhanced from 80.59% to 96.27% after soaking in 2%(mass) citric acid solution for 2h, soaking with 1%(mass) ethylenediamine tetra-acetic acid tetrasodium salt and 0.3%(mass) sodium tripolyphosphate solution for 1.5 h. According to the result of SEM images and AFM images, the forward-osmosis cleaning strategy could not cause the damage of selective layer of membrane surface and caused the drop of inorganic and organic fouling on the membrane surface. Hence, cleaning fouled RO membranes by such approach could prolong the chemical cleaning cycle and reduce the amount of chemical cleaning agent, which has certain industrial application perspectives.     

Advanced treatment of secondary sewage effluent by membrane process

The experimental results on advanced treatment of secondary sewage effluent by ultrafiltration (UF) and reverse osmosis (RO) are presented in this paper, particularly focused on pretreatment system, operating condition, membrane cleaning system, and product water quality.     

复合膜反渗透装置的运行研究

本文介绍了ＥＬＧＡ反渗透装置的运行实验，通过对实验结果的分析讨论提出了二次脱盐理论：溶液区溶质化学位相－膜相分离脱盐及膜区膜压的玻尔兹曼分布脱盐。应用二次脱盐理论，分析ＲＯ装置的脱盐率与各运行参数之间的关系，从而代到了其最佳运行状态和清洗反渗透膜的最好方法。     

Nanofiltration and reverse osmosis of model process waters fromthe dairy industry to produce water for reuse

In dairy plants the process waters generated during the starting, equilibrating, interrupting and rinsing steps contribute to the production of effluents. They correspond to milk products (milk, whey, cream) diluted with water without chemicals. The treatment of these dairy process waters by nanofiltration (NF) or reverse osmosis (RO) operations was proposed to concentrate dairy matter and to produce purified water for reuse in the dairy plant. The study reports one-stage and two-stage (NF + RO and RO + RO) spiral-wound membrane treatments with five model process waters representative of the main composition variations observed in dairies. Performances (permeate flux, milk components rejection, purified water characteristics) of the different operations were compared. Discussion was focused on the comparison between quality of produced waters and vapour condensates (from product drying and evaporation processes) reused in dairy plants. Accordingly, both total organic carbon (TOC) and conductivity of water treated by a single RO or NF + RO operations were convenient for reuse as heating, cooling, cleaning and boiler feed water. With the two-stage RO + RO process, a more purified water complying with the TOC drinking water limit was achieved.     

高频三角波电磁场防治水系统中微生物污垢的研究

工业水系统中微生物污垢广泛存在，实验采用高频三角波对模拟工业水系统中的微生物污垢的防治进行了研究。主要考察了不同流速的流体在未处理和经过不同频率高频三角波处理后，不同材料表面上微生物污垢的生长量的差别以及微生物污垢的生长厚度和形态方面的差异。结果表明：一定流速下5000Hz高频三角波电磁场对实验中使用的非金属材料有明显抑制其表面微生物污垢生长的作用，但是对实验中的金属材料没有抑制作用；高频三角波的抑制作用在距离加载位置较近的实验段比在距离较远的实验段的作用突出，随着与加载位置距离的增大，抑制作用逐渐减弱。     

旋流强化中空纤维膜组件结构优化及壳程流动研究

提出并优化了一种旋转流强化的膜组件水力学模型。Box-Behnken方法用于进口直径、进口长度、膜壳高度、进/出口端管长度、球突结构直径,进出口倾斜角度的多参数的实验设计,获得了响应变量最优的膜组件设计方案。通过雷诺应力RSM湍流模型与基于Euler-Lagrange算法的离散相DPM模型的耦合计算,模拟研究了三维模型内液固两相流的颗粒停留时间分布、流体力学特征。模拟结果显示,旋流强化的膜组件壳程的速度分布更加均匀,膜面剪切应力高;湍流耗散率、涡量分布不同于传统膜组件。实验结果证实,优化后的膜组件具有高产水量、低压力降,膜污染速率低的特点。     

反渗透膜的污染及在线清洗

随着反渗透装置的投运,反渗透膜的污染因其预处理工艺、预处理效果以及各地水源水质的不同,会产生各种各样的污染。反渗透膜污染到一定程度,就必须进行清洗。而反渗透膜的清洗,尤其是在表洗是我国反渗透应用中的一大难题。文中主要介绍了卷式反渗透膜污染的原因、特征以及在线清洗配方的选择、操作注意事项和清洗实例等,以供同行参阅。     

Optimal design of nanofiltration system for surface water treatment☆

Both reverse osmosis (RO) and nanofiltration (NF) membranes have been increasingly used for water purification and desalination. However, the salt rejection of NF membranes is quite different from that of RO membranes, which makes a significant distinction in their process designs. This work started from the performance investigation of a single NF membrane element and then focused on the process design of the NF system for surface water treat-ment. In experimental tests, it was found that the observed rejection of the NF element becomes nearly constant when the concentrate flow is large enough, while the membrane flux of the NF element is quite stable regardless of the water flow across the membrane surface. These findings can be used to instruct the process design of the NF system for surface water treatment. In process design, a two-stage arrangement is sufficient for the NF system to reach the highest water recovery, while the RO system requires a three-stage arrangement.     

反渗透膜清洗剂的实验评价方法

添加阻垢剂是反渗透系统重要的预处理方法之一,但膜在运行中还是会被反渗透过程中沉淀出的不溶性物质所逐渐污染.为了克服污染,必须对膜进行的定期清洗.反渗透市场上每年都会推出新的清洗剂,如何评价这些反渗透清洗剂及销售商提供的清洗程序至关重要.文章提供一种快速、方便、可靠的膜清洗剂试验方法.