改性PVDF膜在MBR中膜污染的研究

将聚偏氟乙烯膜磺化6 h,在TiO2胶体溶液中浸泡20 min,制得的TiO2改性膜纯水通量约为1 800L/m2·h,高出未改性膜250L/m2·h.通过膜生物反应器中膜阻力的测定,分析膜污染形成的原因,表明膜污染主要是浓差极化层及凝胶层引起的;通过活性污泥对膜污染机理的研究,判断出污泥的过滤过程严格符合沉积过滤定律.在膜生物反应器(MBR)中运行时,TiO2改性膜稳定通量高于未改性膜,总阻力低于未改性膜;通过扫描电镜分析,TiO2改性膜沉积层的厚度比未改性膜薄,表明TiO2改性膜的抗污染性能优于未改性膜.     

聚偏氟乙烯膜生物反应器处理城市污水的膜污染分析

膜污染是制约膜生物反应器应用的关键因素,通过实验分析了聚偏氟乙烯膜生物反应器运行操作压力的变化.膜通量为10/L(h·m2)时,操作压力在3.73×104Pa以下,比较了降低膜污染的不同方法:水力清洗能恢复操作压力77%;倾斜50°放置,压力增长缓慢;膜组件离容器底部最佳位置为20 cm.计算了膜总阻力的组成.     

TiO2薄膜改性聚偏氟乙烯膜污染机理

运用溶胶-凝胶原理在聚偏氟乙烯膜表面涂覆二氧化钛胶体颗粒,来改善膜表面的亲水性,延缓膜表面污染时间.通过膜通量、接触角的测定,扫描电镜的观察,得出改性膜既能保持原来的通量,又增大了润湿性,使膜表面被污水中有机物污染时间延长,通过膜阻力分析,找出膜污染的主要原因及清洗后膜通量的比较,最后得出结论,在一定的涂覆条件下,改性膜表面污染能够被延缓,膜污染主要是由污水中有机物在膜表面形成浓差极化及凝聚层造成.     

基于小孔径PVDF内衬膜A/O-MBR膜污染分析

为研究膜生物反应器膜污染问题,在缺氧-好氧一体式膜生物反应器中,对模拟生活污水的处理效果进行考察,考察了4种不同孔径聚偏氟乙烯(PVDF)内衬膜对膜污染的影响规律。结果表明,基于小孔径PVDF膜的MBR工艺对模拟生活污水中COD、NH3-N的去除率分别达到96%、90%,出水浊度在0.35 NTU以下;在操作条件固定的情况下,随着膜孔径增加,临界通量逐渐降低;孔径越小,跨膜压差上升越缓慢,膜污染较轻。膜污染模型分析结果显示:无论何种孔径的膜,在MBR系统中,滤饼层和凝胶层污染所占的比例都最大(>80%),因此,在使用过程中减缓滤饼层及凝胶层的形成至关重要。     

聚偏氟乙烯管式微孔膜的工艺研究

对聚偏氟乙烯(PVDF)管式微孔膜生产工艺进行了研究。系统地讨论了相转化法制备管式微孔膜过程中各个因素的影响。研究发现,铸膜液温度对PVDF管式膜截留率和纯水通量影响不明显;铸膜液中加入NH4Cl后,膜的纯水通量增加,截留率减小,孔径增大;不同凝固浴制得的PVDF管式微孔膜不同,膜的纯水通量和截留率也不同。     

改性PVDF中空纤维膜处理汽车脱脂废水的性能研究

采用经过亲水疏油改性的聚偏氟乙烯(PVDF)超滤膜对汽车脱脂废水进行了油水分离研究。结果表明,在跨膜压差0.08～0.10 M Pa,浓水回流量为膜初始通量的2倍,进液温度30～40℃的操作条件下,PVDF膜处理脱脂废水的分离效果最佳。在清洗液温度45℃条件下,采用纯水-HCl-Na OH+十二烷基苯磺酸钠(SDS)清洗方式可基本去除膜的不可逆污染,通量恢复率达97%。膜的稳定通量达15 L/(m~2·h),油、化学需氧量(COD)、浊度的去除率分别达到98.0%、92.9%、98.5%以上,滤液油含量低于15 mg/L、浊度低于5 NTU、COD质量浓度低于1 350 mg/L,在脱脂废水处理方面表现出巨大的应用潜力。     

PVDF/PMMA复合材料膜的性能及应用

介绍了聚偏氟乙烯(PVDF)/聚甲基丙烯酸甲酯(PMMA)复合材料膜以及引入石墨烯之后复合材料膜的性能和应用研究。相关研究表明:PVDF/PMMA复合材料膜在新能源、水处理以及医疗领域有重要的应用价值,在新型膜材料领域具有极大的发展潜力。     

抗污染PVDF膜研究进展

聚偏氟乙烯(PVDF)由于具有优异的力学性能、热稳定性和化学性能而被广泛应用于膜分离技术中,但是,其表面的极强疏水性使其在应用过程中易受到微生物和蛋白类物质的污染,并缩短其使用寿命,因此,对PVDF膜进行改性具有重要的意义.目前,对PVDF膜改性研究主要集中在亲水改性和抗菌改性2方面,通过对膜的亲水性能进行改性能提高其...     

用于处理染料废水的PVDF/TPU共混中空纤维膜的制备

采用相转化法制备PVDF／TPU共混中空纤维膜,以PVP为添加剂可以改善成膜性能。通过水通量超滤实验、牛血清白蛋白截留实验、扫描电子显微镜表征膜的表面与截面结构分析得出铸膜液中纤维膜的质量分数为16％,m（PVDF）：m（11Pu）为80：20,添加5％PVP时制备的膜的综合性能最佳。对不同的溶液包括BSA、PVPK30、PEG10000、染料活性艳蓝KN-R进行截留实验分析膜过滤性能。在pH范围为1—14时,膜的水通量及截留率均无明显变化,说明PVDF／TPU共混中空纤维膜具有良好的抗酸、碱性。用清水冲洗10min后,膜污染的恢复率即可达到86．5％,膜的抗污染性能良好。     

膜法处理乳化油废水的初探

针对乳化油废水的处理，着重研究了聚偏氟乙烯内压管式膜的配方和膜的制备方法，对聚合物含量，压力，温度等影响过量的工艺参数进行了探讨，并通过对比试验，证明与进口膜性能相似，能直接装上整机使用。     

超滤膜净化有机废水及在线水力清洗对膜污染的影响

研究了恒压操作下用聚丙烯腈中空纤维超滤膜净化含腐殖酸类有机物废水的效果。结果表明:超滤工艺几乎可完全去除水中的浊度物质,对水中的天然有机物有一定的去除效果。在反冲洗水量相同的条件下,增加反冲洗频率,可大大减缓膜通量的衰减;频繁的在线水力清洗可有效地去除膜表面的污染物,减轻膜污染。     

超滤装置污染原因分析及处理

本文介绍超滤装置在电厂水处理工艺中使用的基本原理和特点,指出了运行过程中超滤装置被污染的原因,提出了超滤装置被污染后化学清洗的解决对策,通过实践强调了化学清洗恢复膜性能的重要性.     

Effect and mechanism of ultrafiltration membrane fouling removal by ozonation

This study is aimed using ozonation to remove the fouling that occurs on ultrafiltration membranes. Polyvinylidene fluoride (PVDF) was utilized for the membrane material. The tertiary effluent from industrial park wastewater plant was treated by an ultrafiltration membrane process. A bench-scale system was performed to evaluate the efficiency of fouling removed by an ozonation process. The results should be a valuable reference encouraging the recovery of tertiary effluent by the membrane process. The ozonation process was done via the direct continuous dosing of ozone into the influent. The ozone gas mass flow rate was 8.79 mg/min; the residual ozone concentration in the influent flow was maintained at about 4.02 mg/L throughout the test. It was demonstrated that without ozonation the permeate flux dropped to 60% after 1 h, but that with ozonation it could be maintained at 90% through the test. The SEM observations showed that much fouling that had clogged the membrane was effectively removed by ozonation. The mechanism of fouling removed was also illuminated by the IR analysis. It was observed that the ozone could oxidize and destroy the organic fouling, and the cross flow could flush away any loose fragments on the filtration cake.     

一种基于膜污染指数的超滤膜污染评价方法

利用浸没式中空纤维膜小试系统,基于膜污染指数（FI）建立超滤膜污染的评价和试验方法。通过试验考察超滤膜污染变化规律,以及运行周期对膜污染指数计算的影响,并确定计算膜污染指数的运行周期;并对膜污染指数评价方法的可重复性进行检验：对化学清洗前后膜污染指数进行比较。试验表明,在过滤初期,滤饼污染和吸附污染并存,所以初期水力不可逆膜污染指数（HIFI）增长较快;中期超滤膜的吸附能力不断减弱,膜污染主要是滤饼污染,所以膜污染较为稳定：后期跨膜压力过大,压缩滤饼层,减小滤饼孔隙率,增加滤饼阻力,所以HIFI有所增加。同时短期的膜污染试验可以用来反映长期的膜污染情况,该超滤膜污染的评价方法重复性好,污染后的超滤膜经过化学清洗后。可以重复利用。     

On the fouling mechanism of polysulfone ultrafiltration membrane in the treatment of coal gasification wastewater

Membrane fouling has been investigated by using a polysulfone ultrafiltration membrane with the molecular weight cutoff of 20 kDa to treat crushed coal pressurized gasification wastewater. Under the conditions of different feed pressures, the permeate flux declines and rejection coefficients of pollutants referring to three parameters (total organic carbon (TOC), chroma and turbidity) were studied. The membrane fouling mechanism was simulated with three classical membrane fouling models. The membrane image and pollutants were analyzed by scanning electron microscopy and gas chromatography-mass spectrography (GC-MS). The results indicate that the permeate flux decreases with volume reduction factor before reaching a constant value. The rejection coefficients were also measured: f_TOC = 70.5%, f_C = 84.9% and f_T = 91%. Further analysis shows that the higher the feed pressure is, the sooner the permeate flux reaches constant value and the more sharply the permeate flux declines. Constant flux indicates a nonlinear growth with feed pressure (P_F): when P_F equals 1.2 bar, the mark for the critical flux, slight membrane fouling occurs; when P_F exceeds 1.2 bar, cake layer pollution aggravates. Also the rejection coefficients of global pollutant increases slightly with P_F, suggesting the possibility of cake compression when P_F exceeds 1.2 bar. Through regression analysis, the fouling of polysulfone ultrafiltration membrane could be fitted very well by cake filtration model. The membrane pollutants were identified as phthalate esters and long-chain alkenes by GC-MS, and a certain amount of inorganic pollutants by X-ray photoelectron spectroscopy.

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Analysis of fouling mechanisms and membrane cleaning during ultrafiltration of bee venom

ABSTRACT

The knowledge about permeate flux decline regarded to apitoxin can be a useful tool to allow industrial fractionation of the mixture. Hermia’s models were used to predict the fouling mechanisms during cross-flow ultrafiltration of bee venom in 10 kDa regenerated cellulose membrane. Three different apitoxin concentrations (0.2 to 1 g/L) were tested at 1 bar and 0.08 m/s. Fouling mechanisms varied as a function of feed content. Membrane cleaning with sodium dodecyl sulphate was effective. Phospholipase A₂ rejection coefficients were a function of membrane fouling, varying from 35 to 93%.     

超滤过程膜污染控制技术研究进展

探讨了超滤过程中的浓差极化和膜污染形成的机理以及影响膜污染的因素 ,综述了预防和控制膜污染的各种技术 ,包括膜材及孔径的选择、膜组件的设计、原料的预处理、膜过程的强化及膜的清洗等技术。指出开发新型实用的耐污染膜和能耗少、寿命长、抗污染的膜组件 ,对膜过程工艺进行优化控制 ,开发高效的在线清洗技术和经济便利的离线清洗技术等是尚待攻克的课题。     

Intermittent ultrasound-assisted ceramic membrane fouling control in ultrafiltration

In this study, remediation of ceramic membrane fouling by an in-line intermittent ultrasound system was investigated. A piezoelectric ultrasonic transducer was integrated into a membrane unit that provided ultrafiltration (UF) of a diluted skim milk solution containing 0.10 wt% of protein. The effects of ultrasound at varied frequencies (20, 28, and 40 kHz) and power intensities (1.44, 2.88, and 5.76 W/cm²) under continuous operation and intermittent mode at various intervals (0.50, 1.0, 1.5, 2.0, 2.5, and 3.0 minutes) on membrane fouling were studied. The quality and flow rate of the permeate stream were monitored for the evaluation of the UF process performance. Optimal conditions of continuous ultrasound were found at 28 kHz and 2.88 W/cm². Moreover, at optimal ultrasonic conditions, the optimal intermittent time was found at 0.50 minute. At optimal ultrasonic conditions, the permeate amount increased by 79.8% and 94.2% for 0.50 minute intermittent ultrasound and continuous ultrasound, respectively, as compared with that of the UF process without ultrasound. Also, intermittent ultrasound induced better fouling control at a lower protein concentration of 0.05% by weight. The cleaning effect of ultrasound could be attributed to the cavitation bubbles generated by the rarefaction and pressure cycles of the applied ultrasound.     

微生物固定法降解含油污水的研究进展

随着微生物固定化技术的发展,越来越多的研究成果应用于环境治理领域。固定化技术在废水生物治理领域中具有独特的优势和巨大的潜力。本文主要介绍了吸附法和包埋法这两种固定化方法载体的选择和制备方法,探讨了固定化技术对微生物生理特性的影响,综述了固定化技术在修复石油污染方面的应用,总结了固定化微生物技术在实际应用中存在的不足。