Contribution of Main Pollutants in Oilfield Polymer-Flooding Wastewater to the Total Membrane Fouling Resistance

Polymer flooding technology has been used in the oilfield, but huge amounts of polymer-flooding wastewater are produced with oil extraction. Therefore, the treatment and recycle of this wastewater become very significant. In this study, the membrane technology was used to treat synthetic oilfield polymer-flooding wastewater in laboratory-scale dead-end/cross-flow test unit with flat polyvinylidene fluoride (PVDF) membrane (MW 100 kDa). We systematically inspected the membrane fouling mechanism, the variety of total fouling resistance, the dominant resistance, and the filtration proceeds in the filtration process. The orthogonal method and multivariate linear regression method were applied to analyze the influencing degree of main pollutants concentration which contains partially hydrolyzed polyacrylamide (HPAM), oil and suspended solid on the total membrane fouling resistance. According to a comparison of the average rates of change of total membrane fouling resistance for the HPAM concentration, oil concentration, and suspended solid (SS) concentration in single solute solution, double solute solution, synthetic oilfield polymer-flooding wastewater, and the value of pH, HPAM can decrease the average rate of change of total membrane fouling resistance for other two solutes and has the crucial effect on the total membrane fouling resistance. The sequence of influence degree on the total membrane fouling resistance is the HPAM concentration > oil concentration > suspended solid concentration. Moreover, the membrane cleaning effect was studied by using SEM images and the pure water flux.     

聚合物驱含油污水的聚集特性研究

通过测定聚合物驱含油污水中油珠、絮体及Zeta电位的大小,研究了污水油含量、固体悬浮物含量、聚合物浓度对油珠及悬浮物的亚微观聚集形态、表面电荷及污水稳定性的影响。结果表明,随聚合物浓度或油含量的增加,污水中的油珠、絮体均有变大的趋势;随固体悬浮物浓度的增加,污水中的油珠、絮体不仅有变大的趋势,且大尺寸的絮体数量显著增加。聚合物浓度对带电颗粒的Zeta电位有显著的影响,聚合物浓度越高,带电颗粒的Zeta电位绝对值越高。表明聚合物是聚合物驱采油污水处理低效的原因。     

焦化生化出水电渗析脱盐研究

采用电渗析技术对焦化生化出水如曝气生物滤池出水及反渗透浓水进行脱盐,考察不同废水中的离子迁移、废水脱盐及离子交换膜污染情况。结果表明:2种焦化废水采用电渗析处理具有较好的脱盐效果,其中不同离子的迁移脱除与其浓度、离子半径等密切相关。膜电阻测试表明,不同焦化废水电渗析体系中不同离子交换膜的污染存在差别。扫描电镜和红外分析表明,曝气生物滤池出水主要由有机物造成阴离子交换膜污染,而反渗透浓水主要在电渗析浓室侧的膜表面形成颗粒状的无机污染,且阳膜浓室侧比阴膜浓室侧更显著。     

电渗析处理印刷线路板废水的研究

用电渗析技术研究了从印刷线路板废水中精制回收Cu2+的效能。试验结果表明,电渗析能有效富集线路板废水中的Cu2+。当电压为15 V,进水Cu2+、CODCr的质量浓度分别为257、507 mg/L时,Cu2+的富集倍数为2.29,淡室出水的Cu2+质量浓度为0.9 mg/L,Cu2+的去除率达99%,对CODCr的去除率达到43%。但电渗析连续运行结果表明,离子交换膜发生膜污染,产生浓差极化,影响Cu2+的富集,使用的膜还有待改进。     

工业废水电渗析过程中膜污染研究进展

综述了工业废水电渗析体系膜污染类型、性质、影响因素等的研究进展. 无机污染主要是Ca2+, Mg2+或其他高价离子在离子膜表面或内部形成的结垢现象,原理是极化或溶液过饱和形成沉淀. 有机污染是由蛋白、腐植酸、表面活性剂及大分子有机物在离子膜表面沉积或渗透到膜内部而形成,原因主要是带负电荷的有机物与阴膜荷正电基团的静电作用及带苯环有机物与基膜的亲和作用,其次是有机物分子大小与膜的网络结构的作用. 膜污染形成及其性质与施加电流、共存组分、温度、pH值和运行时间等密切相关,可造成离子膜导电性、离子交换容量、水含量和极限电流密度等减小,且有机污染对电渗析性能的影响比无机污染更严重. 由有机物凝胶层形成的膜污染可用电渗析膜污染指数定量描述.     

双极膜电渗析脱除苏氨酸母液中硫酸盐

采用三室双极膜电渗析脱除苏氨酸母液中硫酸盐,探讨连续操作对电渗析器性能变化的影响,并测定连续实验前后离子交换膜的面电阻,考察膜污染情况. 结果表明,苏氨酸母液中盐转化率达97%,酸室中得到0.50 mol/L的H+,碱室中得到0.53 mol/L的OH-,以阳离子计算的电流效率为60.33%,能耗为229.37 kW×h/kmol;随批次增加、操作时间延长,单位膜通量能耗和膜堆平均电阻增大,电流效率和膜通量减小,电渗析器性能下降;连续操作后,阴膜面电阻较使用前增加1.77 Ω×cm2,升高44.8%,双极膜面电阻增加0.91 Ω×cm2,升高19.5%,离子交换膜被污染.     

阴离子交换膜改性及抗污染性能研究进展

电渗析技术应用于工业废水脱盐时,废水中有机物及其它杂质组分等会造成膜污染,进而影响脱盐性能。电渗析膜污染防治对促进电渗析在工业废水处理中的应用有重要意义。相比于阳离子交换膜,阴离子交换膜更易形成有机污染,且更严重。阴离子交换膜污染主要由腐殖酸、牛血清蛋白、阴离子表面活性剂等有机物造成,污染过程主要受静电作用、亲和作用和几何因素的影响。膜改性提高阴离子交换膜的抗污染性能是电渗析膜污染防治的有效方法,目前已有许多有关膜改性提高阴离子交换膜抗污染性能的报道。膜改性方法主要有化学改性法、等离子体改性法、表面涂覆改性法、电沉积改性法、自聚合改性法及改进基膜结构法等。本工作对阴离子交换膜改性及抗污染性能的研究进展进行了综述,对不同改性方法的优缺点进行了分析和评价。这些改性方法能提高阴膜表面的负电荷密度和亲水性、降低膜表面粗糙度和基膜含水率等,因此可以改善阴离子交换膜的抗污染性能。然而,目前研究获得的改性阴离子交换膜仍存在修饰层不稳定、抗污染性能不理想和性能测试不系统等缺点,需进一步优化改性方法、改性工艺、组分修饰及性能测试等,以获得抗污染性能稳定且效果良好的改性阴离子交换膜。     

A comparative study of tertiary membrane filtration of industrial wastewater treated in a granular and a flocculent sludge SBR

Membrane fouling has been identified by many researchers as an inconvenience for the industrial application of membranes in wastewater treatment plants. Membrane fouling decreases permeability and therefore permeates flow, increasing costs. Although fouling is the result of complex phenomena not completely known, it can be said that fouling takes place by the presence of three different kinds of compounds in the water: suspended solids, colloids and solutes. In this sense, the characteristics of the suspended solid aggregates might be an important aspect in order to diminish the impact of suspended solids on membrane fouling. The main objective of this study was to compare the operation of two similar tertiary membrane filtration units treating the effluent of two different SBRs, respectively: A granular sludge SBR (GSBR) and a membrane flocculent sludge SBR system, at laboratory scale. Two PVDF microfiltration membrane modules were used for tertiary filtration of the effluent treated in the SBRs. Both reactors were used for treating the wastewater generated in a factory of the fish freezing sector. COD of the wastewater was between 700 and 1100 mg/L, total nitrogen concentration was between 110 and 180 mg N/L and total phosphorus ranged around 110 mg P/L. The chemical characteristics of both permeates were similar. Moreover, the presence of either granules or flocs in the tertiary membrane filtration systems did not have an appreciable impact on the membrane filtration. Nevertheless, it was observed that the operation of the membrane on the flocculent system tends to be more instable, showing a major tendency to achieve critical flux.     

Submerged Membrane Bioreactor for Vegetable Oil Wastewater Treatment

A bench‐scale submerged membrane bioreactor (SMBR) was employed to treat vegetable oil plant wastewater with complete sludge retention. Treatment performance and membrane fouling of the SMBR were investigated. The system stably removed high amounts of total organic carbon, oil, and ammonia from vegetable oil wastewater and reduced the chemical oxygen demand, demonstrating the great potential of the SMBR in removing pollutants. The membrane fouling layer was not only governed by deposition of organic substances composed of extracellular polymeric substances like proteins, polysaccharides etc., and oil substances but also by inorganic elements. Organic foulants coupled to inorganic precipitation enhanced the formation of a gel layer and triggered severe membrane fouling in the SMBR.     

Membrane fouling caused by amino acid and calcium during bipolar membrane electrodialysis

BACKGROUND: Bipolar membrane electrodialysis (BMED) has been widely applied in the recovery/production of organic acids and in the treatment of wastewater containing ammonium sulfate, sodium nitrate, sodium acetate and ammonium nitrate. However, membrane fouling is still one of the major problems in the electrodialysis process. Since calcium and amino acid are present naturally in fermentation wastewater, this study was carried out to determine the effects of calcium and amino acid on membrane fouling when simulated fermentation wastewater containing ammonium sulfate was treated by BMED. RESULTS: Calcium formed a scale on the cation exchange membrane (CEM) surface in contact with the base cell, but this had no significant adverse effect on the BMED performance. Amino acid, however, caused CEM fouling of the inner membrane, which hampered the BMED process. The coexistence of calcium and amino acid aggravated the membrane fouling, as observed morphologically on the CEM surface on the base cell side. Elemental mapping analysis showed that the membrane foulant was composed of calcium hydroxide and amino acid. CONCLUSION: The CEM fouling caused by calcium and that due to amino acid, which were distributed differently on the membrane, had different effects on the BMED performance. The coexistence of amino acid and calcium deteriorated the CEM fouling during BMED. Copyright © 2008 Society of Chemical Industry     

渗透模式影响纳米涂层修饰陶瓷微滤膜分离性能的研究

研究了膜分离技术处理含油废水存在因油滴变形引起的膜堵塞问题。为减少膜污染,使用在市场上销售氧化铝微滤膜孔道表面制备纳米ZrO2涂层,利用纳米涂层改变微滤膜的表面亲水憎油性,具有良好的效果。考虑其工业应用条件,重点研究了循环模式（模拟大量废水处理）和浓缩模式（模拟少量废水处理）对膜渗透通量的影响。结果表明：循环模式下料液的油浓度为恒定的,纳米涂层能有效提高微滤膜的渗透通量。膜面流速的增加在一定程度上能提高膜渗透通量,但超过一定程度后,增加不明显。当膜面流速为7m／s时,修饰陶瓷膜的最大渗透通量为280L／（m^2·h）,油截留率为96．4％。在浓缩模式下,料液的油浓度随渗透液的排出呈指数性增加,随着油浓度的增加,渗透通量持续衰减,油截留率持续上升。当油浓度达到一定程度后,修饰陶瓷微滤膜不能有效地实现稳定含油废水的油水分离。     

扩散渗析-电渗析回收赖氨酸离子交换废液中的盐

为缓解电渗析膜污染,提高电渗析性能,采用阴膜扩散渗析对待脱盐的赖氨酸离子交换废液进行净化处理,对扩散渗析回收的(NH4)2SO4溶液进行电渗析脱盐浓缩。结果表明,当扩散渗析流量为5.6 L/h时,扩散渗析的扩散系数达2.24?10?7 cm2/s,离子交换废液中(NH4)2SO4透过率约为30%,可截留90.1% Mg2+和94.5%有机氮、80.3%蛋白、86.0%总糖、79.3%化学需氧量(COD);与直接电渗析赖氨酸离子交换废液相比,对扩散渗析回收的(NH4)2SO4溶液进行电渗析脱盐浓缩,SO42?膜通量、电流效率分别提高了55.7%和18.3%,操作时间、单位膜通量能耗分别降低了26.1%和42.3%。用扩散渗析净化赖氨酸离子交换废液可有效缓解后续电渗析的膜污染,提高电渗析性能。     

Effects of silica sol on ion exchange membranes: Electrochemical characterization of anion exchange membranes in electrodialysis of silica sol containing-solutions

The fouling potential of the negatively charged silica sol in electrodialysis (ED) by adsorption on the surface of an anion exchange membrane was investigated. Since the fouling potential is related to the physical and electrochemical properties of the silica sol and anion exchange membranes, it is important to characterize the properties of silica sol and membranes. The surface charge of silica sol was investigated by the electrophoretic mobility and its isoelectric point was determined as pH 3. The commercial anion exchange membranes were characterized in terms of exchange capacity, water content, the zeta potential and the electrochemical properties of the membranes using impedance spectroscopy to predict the effects on the electrodialysis performances. Among the characterized properties, exchange capacity and some electrochemical properties of the anion exchange membranes were rather improved after ED experiments. In the electrodialysis of solution containing silica sol, deposition of the silica sol did not decrease the desalting performance of the anion exchange membranes because of loosely packed cake layer on the membrane surface.     

离子膜电解技术在废水处理中的应用研究进展

离子膜电解是电渗析和电解结合的具有综合功能特性的技术,近年来在废水处理方面的应用逐渐兴起.根据离子膜电解技术在污染治理中已取得的成果,对离子膜电解技术处理废水的原理及应用现状进行了综述,并对其存在问题及今后发展方向作了一定的探索.     

Characterization of anion exchange membranes with natural organic matter (NOM) during electrodialysis

Natural organic matter (NOM) is thought to be a major source of fouling during membrane filtration of natural waters. The organic matter present in surface waters was characterized in terms of its molecular weight distribution, acidity and electrokinetic properties. The fouling potentials of anion exchange membranes were predicted by the characterization. Changes in the physicochemical properties of anion exchange membranes were also examined during electrodialysis (ED) process of solutions containing NOM. The ED performances were evaluated for the three anion exchange membranes (AMX, AM-1 and ACM) in the presence of NOM. Fouling phenomena in terms of current efficiency and NaCl flux were in good agreement with the fouling potentials predicted by the characterization results. Observations of the molecular weight distribution and the constituents of NOM revealed that the hydrophobic NOM fraction with high molecular weights deposited mainly on the membrane surface, providing fouling effects on the anion exchange membrane.     

Fouling mitigation in the repeated batch runs of electrodialysis with humate foulant

Since membrane fouling is one of the important considerations in electrodialysis, many approaches have been considered in order to minimize fouling of the process. In this study, square wave powers having pulsing effects were employed to investigate the effects of the frequencies on the fouling mitigation during fouling experiments of humate, forming a loosely packed fouling layer on the anion exchange membrane surface. It was shown that a pulsing electric field with determined optimal frequency reduced the fouling potential of an already fouled system in repeated batch runs at a significant level. It was suggested through electrodialysis experiments of humate that the pulsation of the electric field affected the electromigration of the charged particles deposited in the fouling layer, thus decreasing fouling potentials.     

New configuration of a membrane bioreactor for effective control of membrane fouling and nutrients removal in wastewater treatment

Excess aeration to membrane surface is common for controlling membrane fouling in a submerged membrane bioreactor (MBR) system, but significant energy is consumed for excess air production. Therefore, an alternative strategy for membrane fouling control is currently needed. A new configuration of MBR was proposed in this study to control membrane fouling effectively. To reduce biosolids concentration near the membrane surface, the position of the membrane module in MBR was elevated from the bottom to the top in the reactor. This could divide the reactor to two different zones: upper and lower zone. Air was not supplied at the lower zone whereas aeration was given to the upper zone where the membrane filtration was carried out. Biosolids concentration was reduced in the upper zone because the mixed liquor was settled down to the lower zone. Membrane fouling could be lessened in the upper zone due to the reduced biosolids concentration. Therefore, to verify if this new configuration of MBR could mitigate membrane fouling, the effect of changing vertical position of the membrane module in MBR on membrane fouling was investigated. Prior to verification the effect of elevation of membrane module on membrane fouling, influence of MLSS concentration on membrane fouling was investigated first. Transmembrane pressure (TMP) increase became steep as MLSS concentration increased. And the immersed membrane module was elevated from the bottom to the top of the MBR. When the upper membrane was located in the bioreactor, less membrane fouling was observed. This could demonstrate a possibility of new MBR design to control membrane fouling. In addition, reduced dissolved oxygen level in the returned sludge to anoxic tank could increase denitrification efficiency if this configuration is directly applied to biological nutrient removal processes.     

Removal of hardness in fermentation broth by electrodialysis

Lysine fermentation broth was desalinated by electrodialysis to reduce hardness concentrations as a pretreatment procedure for the purification and recovery of amino acids. Electrodialysis performance was investigated in terms of the rate of reduction in conductivity in dilute solutions and electrodialysis cell resistance for different ion exchange membranes at a constant current density. Among the membranes investigated in this study, membranes with high water content showed the better performance for hardness removal. Fouling experiments revealed that organics gave rise to fouling effects on the anion exchange membrane during demineralization of the lysine fermentation broth. The pulsed electric field with the half‐wave power enhanced the electrodialysis performances by mitigating membrane fouling in desalination of the lysine fermentation broth. This study successfully demonstrated the potential use of pulse power as an effective cleaning‐in‐place (CIP) method during electrodialysis of fermentation broth. © 2002 Society of Chemical Industry     

滑石粉减缓膜污染作用的小试研究

膜生物反应器以其突出的优点迅速成为污水处理的新的发展方向,但一直以来膜污染都是其推广应用的障碍.在膜生物反应器中投加滑石粉,主要通过膜通量等参数来研究滑石粉对膜污染的减缓作用,试验结果表明当滑石粉的投加量为1.4 g/L时膜通量下降最为缓慢,污泥沉降性能也相对较好.     

Macroreticular anion exchange membranes for electrodialysis in the presence of surface water foulants

In this work two new types of anion exchange membranes having pore sizes of macro dimensions are described. Static and dynamic fouling resistance to common large anions found in surface waters is evaluated. Improvements over conventional microporous anion membrane types are discussed with respect to electrodialysis.