胶州湾海水纳滤软化的研究

采用超滤-纳滤膜集成膜技术，进行了胶州湾海水纳滤软化现场试验，筛选了纳滤膜，考察了料液流量、操作压力对纳滤膜元件运行效果的影响，评价了纳滤作为海水淡化预处理对海水中主要离子的截留效果，并进行了短期试验。结果表明超滤-纳滤膜集成技术可为淡化系统提供优质的软化水，为胶州湾地区膜法海水淡化奠定了基础。     

软化海水与海上绥中36-1油田储层配伍性研究

针对绥中36-1油田油藏条件,开展了纳滤软化海水与绥中36-1油田地层水及油藏的配伍性研究。利用ScaleChem结垢软件对软化海水在不同温度、压力下的结垢倾向进行了预测,并进行了岩芯伤害性实验。结果表明:软化海水在温度为65℃条件下,压力为0~20 MPa范围内,没有结垢物质生成,在压力为12 MPa条件下,温度为0~100℃范围内,也没有结垢物质生成;软化海水可以任意比例与地层水混合,无沉淀生成;软化海水的渗透率伤害仅为11.9%,对地层为弱伤害。纳滤软化海水可用于海上油田注水。     

海上纳滤水处理技术研究与应用

海水作为海上油田常用注水水源因存在大量成垢离子易导致后期结垢。通过静态配伍性试验、动态配伍性试验及岩心配伍性试验,考察了纳滤海水与RX-1油田地层水的配伍性。试验结果表明:纳滤海水与地层水混合后几乎无沉淀,岩心驱替100 PV,渗透率下降20%以内。矿场试验结果表明:海水经纳滤处理后,水质稳定,Ca~(2+)由366 mg/L降到平均19 mg/L,Ca~(2+)去除率为94%;SO_4~(2-)由2 690 mg/L降到平均4 mg/L,SO_4~(2-)去除率为99%。纳滤装置1 a的应用结果表明:注入端压力平稳,未出现结垢问题。     

纳滤海水软化过程中膜污染的研究进展

由于海水成分复杂性以及纳滤膜纳米级膜孔与特殊荷电性,纳滤在海水软化过程中的膜污染现象和机理较其它膜(微滤、超滤、反渗透)更为复杂.目前,膜污染已成为纳滤大规模应用于海水软化领域的瓶颈之一和该领域的研究热点.本文综述了有关国内外纳滤海水软化过程中膜污染的研究进展,以及膜污染的表征手段,并针对目前研究现状提出了建议.     

纳滤海水软化性能及膜污染研究

高硬度、浊度和总固溶物（TDS）含量的海水水质是制约海水淡化的瓶颈,孔径介于反渗透和超滤之间、具有荷电性质的纳滤膜在海水软化方面具有明显优势,利用小型平板膜测试设备,以人工海水为研究对象,进行了纳滤海水软化试验研究,考察了操作压力,运行时间对膜通量的影响和膜对海水中主要离子的截留效果,进而对膜污染进行了分析与探讨。     

海水/工业含盐废水纳滤除硬技术试验研究

本文利用纳滤除硬技术进行海水淡化和工业含盐废水再生利用进行研究,设计了一套卷式膜纳滤实验装置,选用陶氏纳滤膜NF90-4040和NF270-4040对模拟35‰、45‰、55‰、66‰海水进行软化,考察操作条件对纳滤膜Ca~(2+)、Mg~(2+)总硬度的脱除率的影响,并与药剂法和离子交换法除硬效果进行了比较。     

膜技术在海水淡化浓盐水资源化利用中的试验研究

采用以"超滤+纳滤"(UF+NF)为主体工艺的中试装置对海淡浓盐水进行实验,探究浓盐水资源化利用的可行性。实验结果表明,超滤单元UF出水浊度0.2 NTU,SDI _(15)值0.8,满足后续有机膜单元的进水水质要求。纳滤单元选取2种不同型号纳滤膜进行实验,综合对比DK纳滤膜截留率效果较好,纳滤产水用于氯碱化盐,不仅能够节约纯水,减少原料氯化钠的消耗,同时解决了浓海水排放的问题,实现变废为宝。     

双膜法深度处理油田采出水的现场试验研究

基于油田注汽锅炉给水的要求,利用商品膜组件,进行了(超滤+纳滤)双膜法深度处理油田采出水的现场试验研究.结果表明,超滤预处理效果良好,出水油的质量浓度小于0.06 mg·L~(-1),SDI_(15)小于4.0,满足了纳滤膜进水要求.氢氧化钠+十二烷基磺酸钠(SDS)复合清洗剂对超滤膜污染表现出较好的清洗效果,纯水通量恢复系数高达92%.在较高的回收率下,纳滤对硬度、总溶解固体(TDS)、SS、和COD仍保持高截留率,且保持了稳定的产水通量,系统出水水质达到油田注汽锅炉进水水质指标.(超滤+纳滤)双膜工艺在长期运行过程中,产水通量及水质表现出较高的稳定性.     

不同纳滤膜在软化浓海水性能方面的研究

选用纳滤膜NF270、DK、DL对浓海水进行实验研究。考察了不同操作压力下3种纳滤膜的透过通量、截留性能和分离系数的变化,从而选出适宜软化浓海水体系的纳滤膜。     

超滤作为预处理在纳滤回用电镀废水中的应用

以某电镀厂经化学沉淀处理后的排放水为研究对象研究了超滤预处理对纳滤回用电镀废水的影响.结果表明:超滤预处理对纳滤膜有良好的保护作用,提高了纳滤膜通量达32.46%,增强了回用处理系统运行效率,降低了运行成本,并提高了最终出水水质.     

Rejection of salt mixtures from high saline by nanofiltration membranes

Nanofiltration (NF) membranes have recently been employed as pretreatment unit operations in seawater desalination processes and as partial demineralization to seawater. The present paper investigates the performance of selected commercial NF membranes to reject salts of high concentrations at salinity levels representative of brackish and sea water. Two commercial nanofiltration membranes (NF90 and NF270) have been investigated in detail to study their performance in filtering aqueous solutions containing different salt mixtures in a cross-flow NF membrane process within the pressure range from 4 to 9 bar. Spiegler-Kedem model (SKM) was used to fit the experimental data of rejection with the permeate flux. The results showed that NF90 membrane was shown to have a distinct ability to reject both monovalent and divalent ions of all investigated mixtures with very reasonable values but with relatively low flux. This will make NF90 more suitable for the application in the pretreatment of desalination processes. On the other hand, NF270 can reject monovalent ions at relatively low values and divalent ions at reasonable values, but at very high permeate flux. The SKM model only fitted well the experimental data of divalent ions in salt mixture. Based on the evaluation of the overall performance of NF90 and NF270 membranes, their distinct ability to reject salts at high salinity from seawater is considered an advantage in the field of pretreatment of seawater feed to desalination units.     

膜软化及其应用

膜软化为近十几年发展起来的一种新的水软化工艺,属发离技术中的纳滤分离过程,具有无污染、无需再生、工艺简单、操作方便、设备占地省、出水水质好等优点,在国际上已得到广泛应用。作者主要阐述了膜软化的原理、软化用膜及其性能、膜软化过程及膜软化器设计等方面的内容;详细论述了膜软化在常规水脱硬、高硬度海岛水软化、海水去除硫酸盐和预软化等方面的应用;对膜软化过程的经济性进行了评述,并将膜软化的制水成本与常规软化     

Application on to nanofiltration to water management options for oil sands operation

A membrane separation process, nanofiltration (NF), has been applied successfully for treatment of oil sandswaters, particularly to water softening and removal of toxic components. This study focused on the selection of appropriate membranes and the assessment of their performance for the removal of polyvalent ions (hardness) and naphthenic acids (NA) (the main acute toxicant in oil sands process-affected imported waters) from both imported and potential discharge waters. Experiments were carried out using a bench-scale flat sheet membrane system with several commercially available NF membranes. It was found that after membrane filtration, both water hardness and the NA concentrations were reduced significantly (>95%). A permeate flux was maintained at 15 L/m²/h or higher, with a retentate volume of about 10% of the feed volume.     

Direct filtration of Procion dye bath wastewaters by nanofiltration membranes: flux and removal characteristics

The treatment and reuse of industrial wastewaters by membrane processes has become more attractive in the last few years due to constraints on water usage. The aim of this study was to investigate the direct filtration of reactive dye house wastewaters by nanofiltration membranes based on permeate flux, and sodium chloride and colour removal. Experiments were performed using both synthetic and industrial dye bath wastewaters with the fluxes of the industrial dye bath wastewaters lower than those of the synthetic solutions. The effects of operating conditions such as pressure and pH were assessed. Studies with DS5 DK type (polysulfone–polyamide) membranes showed that nanofiltration membranes are suitable for direct treatment of wastewaters and the permeate quality was appropriate for reuse in the dyeing process. Pre‐treatment and neutralisation were important for recovery of large amounts of salt and water from the permeate stream. Neutralisation of the solution with HCl rather than H₂SO₄ gave a better permeate from the point of view of the reuse. The highest permeate flux and colour removal and the lowest salt removal were achieved with the HCl neutralisation. Copyright © 2003 Society of Chemical Industry     

能量回收装置在海水纳滤脱盐系统中的应用分析

纳滤膜分离技术对2价离子的独特分离功能,使其在海水淡化脱盐、水软化处理等领域具有广泛的市场应用。针对实际工程中海水纳滤脱盐系统的节能需求,建立了"纳滤+能量回收"耦合工艺流程;研究分析了自主开发的能量回收装置产品与纳滤脱盐系统的耦合运行特性,及能量回收装置对系统运行能耗降低的实际贡献率。结果表明,自主开发的能量回收装置与海水纳滤脱盐系统的耦合运行稳定性良好,装置能量回收效率高达96.28%,对纳滤脱盐系统本体运行能耗的降低幅度可达44%。     

Nanofiltration Membrane Process for the Removal of Arsenic from Drinking Water

The removal of arsenic from drinking water by nanofiltration membranes was investigated. Experiments were conducted with tap water to which arsenate and arsenite were added. Two types of nanofiltration membranes, i.e., NF‐90 and NF‐200, have been tested. The effect of various operating conditions, e.g., applied pressure, feed concentration, pH and temperature, were also investigated. The pH and arsenic concentration in the feed and the operating temperature are found to be decisive factors in determining the arsenic concentration remaining in the permeate. The level of removal of As(V) was higher than 98 % for both membranes, but that of As(III) was much lower. It can be concluded that by controlling the operating parameters, source water containing As(V) may be recovered as drinking water to EPA maximum contaminant level quality standards, but that water containing As(III) must undergo a pre‐oxidation treatment before passing through the nanofiltration membrane in order to maintain drinking water quality.     

Novel chitosan-piperazine composite nanofiltration membranes for the desalination of brackish water and seawater

A novel chitosan (CS)-piperazine (PIP) composite nanofiltration (NF) membrane with satisfied characteristics for brackish water and seawater desalination was successfully developed. PIP was mixed with CS during the interfacial polymerization (IP) process to enhance the NF membrane permeate flux. The resultant NF membranes were characterized by X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), atomic force microscope (AFM), contact angle. Effects of CS concentration, trimesoyl chloride (TMC) concentration, reaction time and the mixing ratio of CS/PIP on NF membrane performance were investigated thoroughly. When PIP in the aqueous phase monomers reached to 25% (w/w), the PWF (60.6 L·m^?2·h^?1) was synergistically improved by nearly 2 times without a significant reduction of Na₂SO₄ rejection (89.1%). Moreover, the NF membranes possessed excellent performance for the desalination of brackish water and seawater, which showed high potential to be applied in the desalination process for water treatment.     

Influence of colloidal fouling and feed water recovery on salt rejection of RO and NF membranes

The influence of colloidal fouling and feed water recovery (or concentration factor, CF) on salt rejection of thin-film composite reverse osmosis (RO) and nanofiltration (NF) membranes was investigated. Fouling experiments were carried out using a laboratory-scale crossflow test unit with continuous permeate disposal to simulate the CF and recovery as commonly observed in full-scale RO/NF systems. For feed waters containing only salt (NaCl), permeate flux declined linearly as CF was increased and salt rejection was nearly constant for both RO and NF membranes. On the other hand, a sharp decrease in permeate flux and significant decline in salt rejection with increasing CF were observed under conditions where colloidal fouling takes place. For both RO and NF membranes, the marked permeate flux decline was attributed to the so-called “cake-enhanced osmotic pressure”. The decline in salt rejection when colloidal fouling predominated was much more substantial for NF than for RO membranes. In all cases, the decline in salt rejection was higher under conditions of more severe colloidal fouling, namely at higher ionic strength and initial permeate flux.     

Performance of Nanofiltration Membranes in the Treatment of Synthetic and Real Seawater

Abstract

Nanofiltration membranes (NF) are being employed in pretreatment unit operations in both thermal and membrane seawater desalination processes and as partial demineralization to seawater. In order to predict NF membrane performance, a systematic study on the filtration performance of selected commercial NF membranes against seawater is presented in this paper. Two commercial nanofiltration membranes (NF90 and NF270) have been investigated in details to study their performance in filtering the salt mixture, synthetic and real seawater in a cross‐flow NF membrane process at a pressure range from 4 to 9 bars. The Spiegler‐Kedem model was used to fit the experimental data of rejection with the permeate flux in order to determine the fitting parameters of the reflection coefficient (σ) and the solute permeability (P_s). The results showed that the rejection increases with pressure for NF90 and slightly increases with pressure for NF270. Also, the NF90 membrane has shown to be able to reject both monovalent and divalent of all investigated mixtures and seawater with very reasonable values but at a relatively low flux. Moreover, it reduced the salinity of investigated seawater from 38 to 25.5 g/L using one stage of the NF membrane at 9 bars. This makes NF90 more suitable for the application in the pretreatment of desalination processes. On the other hand, NF270 can reject monovalent ions at relatively low values and divalent ions at reasonable values. It has also reduced the seawater salinity to 33.6 g/L, but at a very high permeate flux. The SKM model fitted the experimental data of divalent ions in salt mixture and seawater.     

Nanofiltration of Magnesium Chloride,Sodium Carbonate,and Calcium Sulphate in Salt Solutions

Abstract

Nanofiltration (NF) membranes have been employed in pre‐treatment unit operations in both thermal and membrane seawater desalination processes. This has resulted in reduction of chemicals used in pretreatment processes as well as lowering the energy consumption and water production cost and, therefore, has led to a more environmentally friendly processes. In order to predict NF membrane performance, a systematic study on the filtration performance of selected commercial NF membranes against brackish water and seawater is required. In this study, three commercial nanofiltration membranes (NF90, NF270, N30F) have been used to treat highly concentrated different salts solutions (MgCl₂, Na₂CO₃, and CaSO₄) at salinity level similar to that of brackish water and seawater. The main parameters studied in this paper are salt concentration and feed pressure. The experimental data were correlated and analysed using the Spiegler‐Kedem model. In particular, the reflection coefficient (σ) of all studied membranes and the solute permeability (P_s) have been determined for all membranes and at different salinity levels of studied salts. All the studied membranes fitted the model well for all investigated salts except the experimental data of MgCl₂ using N30F membrane, which did not fit well at low rejection. The results showed that NF90 produced a high rejection around 97% for all salts with medium permeate flux while NF270 gave a high flux with medium rejection and N30F gave low rejection and flux.