麦芽糖醇的纳滤浓缩

为了节约能耗,采用D和G 2种纳滤膜对麦芽糖醇进行了提纯和浓缩研究。实验中用G膜去除麦芽糖醇中的多糖醇,用D膜除去山梨糖醇和水分。研究结果表明:渗透液的通量随压力、循环流量和温度的增加而增大,而随物料质量分数的增加而减小;另外,截留率随压力和循环量的增加而增大,而随物料的质量分数和温度的增加而减小。综合考虑操作条件对分离效果的影响,最后确定了适宜的操作条件,对于D膜,操作压力为1.2—1.5 MPa,循环流量60—100 L/h;对于G膜,操作压力为1.0—1.2 MPa,循环流量40—60 L/h,操作温度均为40—45℃。     

多糖纳滤浓缩初步研究

本文采用芳香聚酰胺类纳滤（NF）膜,对药厂提供的多糖稀溶液进行浓缩试验研究。结果表明,纳滤（NF）可有效实现对多糖溶液的浓缩,纳滤过程的通量随着进料流量和操作压力的升高而增大,并随着浓缩倍率的增加而下降,且在高浓缩倍率下,压力对通量影响下降,采用定量低压高速侧洗可有效减缓膜面的污染。     

纳滤-Fenton试剂联合作用处理硝基苯废水

为解决高浓度有机物污染地下水的应急处理问题,以峭基苯为目标污染物,研究了纳滤-Fenton试剂组合工艺对硝基苯处理效果;考察了纳滤膜的截留作用以及进水浓度、流量、pH.温度等因素对截留效果的影响.结果表明,在一级一段循环模式条件下,以硝基苯污染原水的实际情况运行,截留率可达64.15%.纳滤过程循环的浓缩液采用Fenton试剂法进行处理,利用正交试验研究H202用量、Fe2+ 浓度、pH和反应时间4个因素对硝基苯废水处理过程的影响,在最佳工艺条件下硝基苯的去除率可达到93%以上.     

纳滤膜技术浓缩分离含镍离子溶液

采用纳滤膜法对较高浓度含Ni2+离子溶液进行了高倍数浓缩,考察了操作压力、进料液流量、原水Ni2+离子质量浓度和pH等因素对分离过程性能的影响.结果表明,纳滤膜对Ni2+的截留率随操作压力、进料液流量和原水Ni2+质量浓度的增加而增大,膜通量则随进水Ni2+的质量浓度增加而减小.对于Ni2+质量浓度为3900 mg·L-1,pH为3的NiSO4溶液原水,在操作压力1.4MPa条件下,经截留液全循环工艺运行,纳滤淡化出水Ni2+的截留率均保持在99.6%以上,浓缩液中Ni2+质量浓度最高可能达到23 510mg·L-1,浓缩倍数超过6.研究表明,选择适宜的纳滤膜用于重金属废水的高倍数浓缩,实现有价金属的资源化回收具有良好的技术可行性.     

纳滤海水软化的实验研究

利用小型平板膜测试设备,进行纳滤海水全回流实验研究.考察了操作压力、流量对DL膜通量的影响和膜对海水中主要离子的截留效果,进而研究在7 h的运行过程中DL膜对海水的软化效果,最后采用扫描电镜与X射线能谱分析纳滤海水软化过程中微溶盐的结晶情况及二价阳离子与海水中有机物的络合作用.结果表明,荷负电DL纳滤膜具备良好的渗透性和分离性能,膜通量随压力的升高线性增加,提高流量通量略有增大.在0.8～2.4 Mpa的压力范围内,DL膜对SO42-和Mg2+的截留率分别保持在98%和70%以上,对Ca2+、Na+和Cl-的截留率是随着压力的升高先增大后保持稳定.随着运行时间的延长,膜通量和离子截留率呈现一定下降趋势.在全回流运行方式下,硫酸钙表面结晶是膜通量衰减的主要原因,海水有机物与二价钙镁离子的络合作用甚微.     

GO改性纳滤膜在富集回收稀土离子中的应用研究

离子型稀土乃国家战略资源,研究浸矿尾水中离子型稀土的富集回收具有重大意义。采用实验室自制的氧化石墨烯（GO）改性纳滤膜和未改性纳滤膜分别对浸矿尾水中离子型稀土进行富集试验。结果表明,两种膜在进料流量为5～6 L/min、操作压力为0.6～0.8 MPa时,对离子型稀土的富集呈现最佳状态,而且GO改性纳滤膜对离子型稀土的富集效果优于未改性纳滤膜。且在最佳操作条件下,未改性纳滤膜和GO改性纳滤膜的水通量分别为15.5～37.35、23.3～48.3 L/（m²·h）;两种纳滤膜对浸矿尾水中稀土离子的截留率分别可达73.4%～89.6%,82.3%～99.2%。通过抗污染性能研究得出,GO改性纳滤膜在持续运行16 h后的纯水通量恢复率约高出未改性纳滤膜16.6%,说明经过GO改性的纳滤膜拥有更强的抗污染性能。     

聚酰亚胺纳滤膜分离螺旋霉素萃取液

研究了不同操作条件对聚酰亚胺纳滤膜分离螺旋霉素一乙酸丁酯萃取液性能的影响。考察了操作压力、温度、进料流量和进料中螺旋霉素质量浓度等因素对膜通量和截留率的影响,并观察了长期运行情况下膜分离性能的变化情况。在适宜的操作条件下,膜通量可达20L/（m^2·h）以上,截留率可达99％以上。试验表明,随操作压力增大、温度升高和进料流量增大,膜通量也随之增大,进料中螺旋霉素质量浓度增加使膜通量减小,不同操作条件对截留率的影响很小。在35d的运行期内膜的分离性能变化不大,表明该膜对此物系具有较强的抗污染能力。     

气提式循环流MBR处理染整废水实验研究及膜污染分析

采用新型的气提式循环流MBR处理染整废水。分析测定进出水水质、膜流量、膜阻力等参数,研究回流比、污泥含量、曝气强度、不同膜组件条件下处理效率以及膜污染状况。结果表明,气提式循环流MBR对印染废水具有良好的处理效果,中空纤维膜和平板膜对COD去除效果分别平均高达96.0%、94.9%,而2者色度平均去除率均高达78.0%,中空纤维膜比平板膜对有机物具有更好的截留效果。高回流比可减缓膜污染,且平板膜效果更明显。2种膜组件的膜污染速率均随污泥含量增加而提高并且2者呈现良好线性关系,而中空纤维膜污染速率的提高更为明显。高曝气强度对减缓2种膜污染有显著效果。     

纳滤膜对高镁锂比盐湖卤水镁锂分离性能研究

纳滤作为一种新兴的膜分离技术,在高镁锂比盐湖卤水镁、锂分离领域具有非常好的应用前景。研究了不同镁锂比、原料液循环流量对镁锂分离过程的影响,并对膜分离过程中的分离机理进行分析。结果表明原料液镁锂比对膜通量影响较小,镁、锂离子截留率及镁锂分离效果均随原料液镁锂比的增加而降低。当原料液循环流量为225 L/h时,镁离子截留率为95%,锂离子截留率为-66%,透过液镁锂比降低至1.2。膜分离传质机理研究表明,镁离子在分离过程中受到较强的介电排斥效应与尺寸筛分效应。纳滤技术能够有效降低高镁锂比盐湖卤水的镁锂比,为后续高纯锂盐的制备提供基础。     

热处理对聚哌嗪酰胺复合纳滤膜性能的影响

针对聚哌嗪酰胺复合纳滤膜的制备过程热处理中存在的可能影响界面聚合程度的因素,采用自制的烘箱对复合纳滤膜进行热处理,并研究膜性能的变化规律。烘箱以变频鼓风机控制空气体积流量为200~1 200 m~3/h。考察了热处理温度、鼓风流量对复合纳滤膜性能的影响,研究了所得纳滤膜的氯化钠与硫酸镁截留率、水通量。对不同鼓风速率所制备的纳滤膜表面进行了扫描电子显微镜与全反射傅里叶红外光谱分析。结果表明,烘箱的鼓风流量和温度共同决定了界面聚合过程,从而最终决定了纳滤膜的水处理性能。     

超细TiO_2粉体洗涤过程中膜污染和再生方法研究

针对陶瓷膜洗涤超细TiO2粉体中Cl-的过程,确定了适合的跨膜压差和膜表面流速,并采用阻力系列模型分析膜污染机理,确定有效的膜再生方法。此过程渗透通量随跨膜压差和膜表面流速的增长而增长,但是增长幅度减缓。合适的跨膜压差和膜表面流速分别为0.10—0.15 MPa和2.0 m/s;主要的膜污染来自粉体在膜表面的沉积;单一的化学和物理清洗方法无法达到理想的清洗效果,采用纯水浸泡、超声波清洗和质量分数0.5%的HCl清洗可使纯水通量恢复至新膜的72%以上,且多次的清洗效果稳定。     

陶瓷膜污染的超声波辅助清洗

膜污染的控制和膜的清洗再生是膜应用的关键,研究了采用超声波辅助清洗被乳化液污染的氧化锆陶瓷膜。结果表明：超声波的功率、超声清洗时间及膜污染程度等对清洗效果均有影响,超声功率越高,清洗后水通量的恢复率越高,超声清洗时间在20 min左右比较适宜。超声波对膜表面的污染清洗效果较好,对膜孔内堵塞清洗效果相对较弱,超声辅助化学清洗可有效恢复膜通量。     

Fouling behavior of poly(vinylidene fluoride) (PVDF) ultrafiltration membrane by polyvinyl alcohol (PVA) and chemical cleaning method

Severe fouling to poly(vinylidene fluoride) (PVDF) membrane is usually caused as filtrating the papermaking wastewater in the ultrafiltration (UF) process. In the paper, fouling behavior and mechanism were investigated, and the low-concentration polyvinyl alcohol (PVA) contained in the sedimentation tank wastewater was found as the main foulant. Consequently, the corresponding cleaning approach was proposed. The experiment and modeling results elaborated that the fouling mode developed from pore blockage to cake layer along with filtration time. Chemical cleaning conditions including the composition and concentration of reagents, cleaning duration and trans-membrane pressure were investigated for their effect on cleaning efficiency. Pure water flux was recovered by over 95% after cleaning the PVDF membrane using the optimal conditions 0.5 wt% NaClO (as oxidant) and 0.1 wt% sodium dodecyl benzene sulfonate (SDBS, as surfactant) at 0.04 MPa for 100 min. In the chemical cleaning method, hypochlorite (ClO^-) could first chain-scissor PVA macromolecules to small molecules and SDBS could wrap the fragments in micelles, so that the foulants were removed from the pores and surface of membrane. After eight cycling tests, pure water flux recovery maintained above 95% and the reused membrane was found intact without defects.     

Membrane fouling and chemical cleaning in water recycling applications

Fouling and subsequent chemical cleaning are two important issues for sustainable operation of nanofiltration (NF) membranes in water treatment and reuse applications. Fouling strongly depends on the feed water quality, especially the nature of the foulants and ionic composition of the feed water. Consequently, appropriate selection of the chemical cleaning solutions can be seen as a critical factor for effective fouling control. In this study, membrane fouling and chemical cleaning under condition typical to that in water recycling applications were investigated. Fouling conditions were achieved over approximately 18 h with foulant cocktails containing five model foulants namely humic acids, bovine serum albumin, sodium alginate, and two silica colloids in a background electrolyte solution. These model foulants were selected to represent four distinctive modes of fouling: humic acid, protein, polysaccharide, and colloidal fouling. Three chemical cleaning solutions (alkaline solution at pH 11, sodium dodecyl sulphate (SDS), and a combination of both) were evaluated for permeate flux recovery efficiency. The results indicated that with the same mass of foulant, organic fouling was considerably more severe as compared to colloidal fouling. While organic fouling caused a considerable increase in the membrane surface hydrophobicity as indicated by contact angle measurement, hydrophobicity of silica colloidal fouled membrane remained almost the same. Furthermore, a mechanistic correlation amongst cleaning efficiency, characteristics of the model foulants, and the cleaning reagents could be established. Chemical cleaning of all organically fouled membranes by a 10 mM SDS solution particularly at pH 11 resulted in good flux recovery. However, notable flux decline after SDS cleaning of organically fouled membranes was observed indicating that SDS was effective at breaking the organic foulant—Ca²⁺ complex but was not able to effectively dissolve and completely remove these organic foulants. Although a lower permeate flux recovery was obtained with a caustic solution (pH 11) in the absence of SDS, the permeate flux after cleaning was stable. In contrast, the chemical cleaning solutions used in this study showed low effectiveness against colloidal fouling. It is also interesting to note that membrane fouling and chemical cleaning could permanently alter the hydrophobicity of the membrane surface.     

Fouling behavior of poly(vinylidene fluoride) (PVDF) ultrafiltration membrane by polyvinyl alcohol (PVA) and chemical cleaning method

Severe fouling to poly(vinylidene fluoride) (PVDF) membrane is usually caused as filtrating the papermaking wastewater in the ultrafiltration (UF) process. In the paper, fouling behavior and mechanism were investigated, and the low-concentration polyvinyl alcohol (PVA) contained in the sedimentation tank wastewater was found as the main foulant. Consequently, the corresponding cleaning approach was proposed. The experiment and modeling results elaborated that the fouling mode developed from pore blockage to cake layer along with filtration time. Chemical cleaning conditions including the composition and concentration of reagents, cleaning duration and trans-membrane pressure were investigated for their effect on cleaning efficiency. Pure water flux was recovered by over 95% after cleaning the PVDF membrane using the optimal conditions 0.5 wt% NaClO (as oxidant) and 0.1 wt% sodium dodecyl benzene sulfonate (SDBS, as surfactant) at 0.04 MPa for 100 min. In the chemical cleaning method, hypochlorite (ClO⁻) could first chain-scissor PVA macromolecules to small molecules and SDBS could wrap the fragments in micelles, so that the foulants were removed from the pores and surface of membrane. After eight cycling tests, pure water flux recovery maintained above 95% and the reused membrane was found intact without defects.     

Cleaning of fouled ultrafiltration (UF) membrane by algae during reservoir water treatment

Ultrafiltration (UF) membrane fouling is often encountered in water treatment. Algae could be removed by UF membrane for its nominal pore size, and the algae cells deposited on the surface of UF membrane. The cells attach to the membrane, they start to release secretion and produce extracellular polymetric substances (EPS), which accumulate on the surface and cause the flux decline. This study examined the effects of hydraulic and chemical cleaning on fouled membrane by algae-rich reservoir water. Four kinds of hydraulic cleaning method were investigated, including forward flushing, backwashing, forward flushing followed by backwashing and backwashing followed by forward flushing. Backwashing followed by forward flushing was more effective for flux recovery, and 20 min duration were enough for the cleaning. To maximize flux recovery for the algae-fouled membrane, chemical cleaning was applied as enhanced cleaning strategies. NaOH, NaOCl, and citric acid were used for cleaning agents. The cleaning with the combination of NaOH (0.02 N) and NaOCl (100 mg/L) was effective than separate uses. And the cleaning duration was determined as 4 h.     

MBR污水处理工艺长期运行中的膜强化清洗方式

基于上海城镇污水处理厂AAO-MBR膜工艺长期运行中膜不可逆污染严重、离线化学清洗难以恢复理想通量的问题,对其清洗方式进行改进。在原清洗方式的基础上增加草酸二次清洗,探究污染膜产水能力恢复情况,并通过中试试验进行验证。结果表明：膜清洗方式改进后,离线清洗对膜污染物的去除更加彻底,清水通量可恢复至新膜的95.1%,较原清洗方式提高了27.2%。在相同通量下中试运行24 d后,膜运行压力比原清洗方式低18.2 kPa,膜污染速率明显减慢。研究通过改进MBR长期运行平板膜的污染物清洗方法,为今后MBR污水厂膜清洗提供参考,具有较好的工程指导意义。     

Development of the MFI-UF in constant flux filtration

The MFI-UF, based on cake filtration, was developed to measure and predict the particulate fouling potential of feedwater to membrane filtration installations. The MFI-UF is determined in constant pressure filtration with the flux deceasing during the test. However, many membrane systems, e.g., reverse osmosis (RO), operate at constant flux with pressure increasing when fouling occurs. As both pressure and flux contribute to cake compression, determining the MFI-UF in constant flux with correction to the flux of an RO system is expected to more closely simulate particulate fouling Therefore, this research investigated the development of the MFI-UF test in constant flux filtration applying low (tap water) and high fouling (diluted canal water) feedwater. Preliminary experiments were promising; the fouling index (I) (and hence the MFI-UF) of all feedwater could be determined within 2 h under constant flux filtration. Cake filtration was demonstrated as (1) a minimum in the fouling indexvs time plot and (2) by linearity of the fouling index with feedwater particulate concentration. The fouling index increased with increasing applied flux due to cake compression. Further investigation at higher and lower applied flux is required to identify a reference test flux and to develop a method to correct the fouling index to the reference test flux and/or the flux of a membrane filtration system The fouling index can then be applied in a model to predict fouling.     

碟管式纳滤膜在生活用水处理中的膜污染特性

采用碟管式纳滤膜对生活用水进行深度处理,研究了不同操作条件对元件分离性能及产水水质的影响,得到最佳运行条件为运行压力1MPa、进水温度为25℃以上、最小浓水流量300L/h。对原水水质进行分析,有效预测了污染物成分及膜污染情况,提出了预处理系统的设计及清洗方案。运用扫描电镜、EDS能谱、红外光谱及三维荧光光谱分析出,从进水端至出水端膜污染逐渐加剧,污染物成分主要以有机污染为主,并且含有难溶盐析出结晶的无机污垢及一定程度的生物污染。对碟管式纳滤膜在生活用水处理中膜污染特性的研究,分析污染成因为难溶盐随浓度增加在膜表面析出形成无机结垢,大量有机物在膜表面吸附形成有机污泥层,而水中微生物或细菌等在膜表面滋生造成生物污染,污染形成顺序为有机污染率先在膜表面形成,随后形成无机污垢,并且会发生相互作用,其结果导致膜通量下降、产水水质变差。本研究借助中试试验探究了碟管式纳滤膜元件的污染特性,为这种新型膜元件在实际生产中如何高效使用及有效控制纳滤膜污染提供依据。     

淹没式加压MBR膜污染机理及治理措施

研究了加压MBR膜通量衰减规律,膜污染阻力的分布;尝试了空曝、水反冲洗、压缩空气反冲洗、物化清洗四种膜清洗方式的膜通量恢复．研究结果表明：加压MBR膜通量衰减迅速,运行17d后膜通量衰减83．5％;膜污染阻力主要由凝胶极化阻力Rp和内部污染阻力Rif构成。