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Thomas C. Timmes 《Desalination》2010,250(1):6-353
The objectives were to investigate the performance of a pilot-scale electrocoagulation (EC) reactor and to determine the feasibility of using in-line EC as a pretreatment to ultrafiltration (UF) of seawater. Work was conducted at Port Hueneme, CA, using components of a U.S. military water purification system. Ferric chloride in-line coagulation was also tested. Both the EC and ferric chloride pretreatments improved UF membrane performance compared to UF without in-line coagulation. EC resulted in slightly greater increases in transmembrane pressure (TMP) than observed following ferric chloride pretreatment during sub-critical flux UF. Substantial accumulation of precipitates developed on the EC electrodes during the testing period. X-ray diffraction identified magnetite, maghemite, lepidocrocite, and akaganeite phases. Accumulation of these precipitates was due in part to conservative hydraulic design of the EC unit. It is recommended that EC units should be designed with short hydraulic retention times and higher electrode current density in order to increase upflow (scour) velocity and thus inhibit accumulation on the electrodes. Progressively longer cycling times for polarity reversal are also recommended. This research indicates that EC offers the potential for a feasible and effective pretreatment strategy for mobile water production facilities. 相似文献
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简要论述了反渗透海水淡化的各种新型膜法预处理技术研究进展情况及其在国内外的具体运用情况,内容主要涵括连续微滤技术(CMF)、浸没式帘式膜过滤、超滤技术、纳滤技术以及陶瓷膜过滤.并指出膜法预处理将成为今后反渗透海水淡化预处理的主要发展方向. 相似文献
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One of the main disadvantages of batch membrane processes is the increase of the pollutant concentration in the feedstock throughout the operation. Operating the plant at constant process conditions leads in many cases to weaker performances and, moreover, to heavy fouling on the membranes. Critical flux-based methods are one of the most used approaches to overcome fouling problems. Within critical flux conditions, only reversible fouling can occur, which can be periodically soft-cleaned.This work studies the relationship between particle size distributions in the feed stream and critical flux values when different pretreatment processes are applied to an olive vegetation waste water stream. The considered pretreatment processes were: coagulation (with aluminum hydroxide and aluminum sulphate), aerobic biodigestion (by means of fungi) and photocatalytic organic matter reduction (by means of nanometric titanium dioxide anatase powders irradiated by UV light). The study was carried out at pilot plant scale (100 L batch capacity).These results were compared with performances and effects on the critical flux value for MF, UF and NF membranes. The different pretreatment on the same waste water stream shifts differently the particle size distribution mainly by organic matter degradation, and this influences heavily the critical flux value and thus the filtration outcome.Finally, the purification of the olive vegetation waste water stream can be performed with a MF, UF, NF and RO membrane system in series, being very careful in choosing the correct operating conditions to avoid the quick formation of an unsustainable fouling. 相似文献
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考察了钙基软化+曝气混凝+超滤+反渗透工艺处理高浓度含磷废水的可行性和可靠性。以钙基软化+曝气混凝+超滤作为反渗透预处理工艺,可有效去除Ca2+、F-、PO43-等会造成反渗透浓水侧结垢的离子,去除率可以达到80%左右,剧毒物质单质磷去除率可以达到85%以上,经超滤后保证出水浊度小于0.5 NTU,超滤产水SDI控制在3.2以下;当反渗透的回收率不大于60%时,反渗透运行稳定,没有出现明显污堵情况。 相似文献
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目前渤海湾反渗透海水淡化工程多采用新型的超滤膜法预处理工艺,为提高预处理效果,主要进行超滤膜材料和性能改进以及膜组件运行参数的优化,而对超滤膜前预处理的研究相对较少。本实验研究了超滤与混凝/超滤作为反渗透海水淡化预处理工艺的处理效果。考察了两种预处理工艺条件下浸没式超滤膜比通量(SF)、进水水质、产水水质,膜孔孔径变化、反洗效果及膜表面污染情况。结果表明,超滤与混凝/超滤两种预处理工艺都能达到产水SDI15<2.0;混凝处理可以大幅度降低海水中颗粒数目,降低颗粒物在膜表面沉积和吸附的概率,减轻超滤膜的污染。当采用混凝/超滤工艺时超滤膜表面滤饼层疏松多孔,膜孔孔径变化较小,超滤膜比通量的衰减速度减缓,反洗时超滤膜比通量恢复率较高。 相似文献
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Electrocoagulation pretreatment of seawater prior to ultrafiltration: Bench-scale applications for military water purification systems 总被引:1,自引:0,他引:1
Thomas C. Timmes 《Desalination》2009,249(3):895-5440
The objectives of this research were to investigate the use of in-line electrocoagulation (EC) as a pretreatment for seawater prior to ultrafiltration (UF) at the bench-scale and to compare EC with equivalent doses of ferric chloride. UF membrane performance was evaluated by transmembrane pressure (TMP) and hydraulic resistances at sub- and super-critical fluxes, and by flux recovery after hydraulic and chemical cleanings. Modified Atlantic Ocean seawater was used. Constant flux UF operation (50 to about 350 lmh) was used to evaluate short-term performance at sub- and super-critical fluxes, and constant feed-pressure (15 psi) experiments were used to investigate filter cake stability under high TMP conditions. In-line EC improved UF membrane performance for all coagulation and flux conditions. Compared to no coagulant pretreatment, ferric chloride improved UF membrane performance under short-term, constant flux conditions that resulted in TMP < 8 psi, but produced increased TMP and resistance to filtration at 15 psi. EC always resulted in lower resistance and improved flux recovery after cleaning compared to an equivalent dose of ferric chloride. Overall, EC is a feasible and competitive pretreatment strategy at the bench-scale, but scale-up issues, electrode cleaning requirements, and sustainability during long-term operation need further study. 相似文献
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海水淡化中空纤维反渗透膜需求量倍增 总被引:1,自引:0,他引:1
罗益锋 《高科技纤维与应用》2011,36(1):1-5
简述了海水淡化中空纤维反渗透(RO)膜的发展历程,并重点介绍国内外以三醋酸纤维素为代表的中空纤维膜发展情况、膜元件的结构特点和技术水平,以及它与卷式RO膜的竞争和市场增长情况.同时简要介绍海水淡化前处理用的中空纤维超滤(UF)和微滤(MF)膜的发展概况. 相似文献
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T. Venkatesh 《分离科学与技术》2017,52(14):2262-2273
The membrane-based grey water treatment for grey water reuse and surfactant recovery is presented in this research paper. Grey water from washing machine discharges having turbidity and used surfactant was processed through the polymeric ultrafiltration (UF) membrane to remove the turbidity. The UF treated grey water is further purified by reverse osmosis (RO) membrane for surfactant recovery and water reuse. The surfactant trapped inside the RO spiral wound membrane module is recovered through various membrane physical regeneration techniques such as backwashing, simultaneous backwash–back-flush and ozone back-flush. Among this, backwash–back-flush is found to be effective process for surfactant recovery. The methodology for optimising surfactant recovery is captured by studying effect of various operating parameters such as feed detergent concentration, backwash pressure, backwash temperature and back-flush flow rate. By implementing optimal process conditions, the integrated UF and RO membrane process is able to produce 300 L of reusable pure water and 80 L of concentrated detergent solution and 20 L of turbid water while treating 400 L of grey water discharges. Maximum surfactant recovery of 82% is obtained while treating grey water which consists of 720 ppm of total dissolved solids (detergent) and 45 ppm of surfactant. The extent of UF and RO membrane fouling is determined by measuring the pure water flux before and after the grey water treatment. The membrane performance is found to be stable when membrane is regenerated by backwash–back-flush technique for RO and gravity backwash for UF membrane. 相似文献
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Study of drinking water treatment by ultrafiltration of surface water and its application to China 总被引:3,自引:0,他引:3
In China, many water supplies depend on conventional water treatment. Due to unfit soil and water conservationin some regions of China, conventional water treatment has showed some defects for the poor quality of water resource. In addition, advances in membrane technology and increasing requirements on water quality have stimulated ultrafiltration (UF) for water treatment. In this research, OF test apparatus was set up to produce drinking water from raw water of the Binxian Reservoir (China). The performance of UF membranes was investigated. There was a linear relationship between membrane resistance and accumulated permeate water. Using coagulation before OF increased permeate flux and retarded membrane flux decline. Surprisingly, membrane permeate flux in a coagulation/UF process was higher than that in coagulation-sand filtration-UF process with raw water of medium turbidity. OF treatment provided effective turbidity removal. Iron, manganese and aluminum were removed completely. The UF membrane also perfectly removed all coliform bacteria. The reduction of total organic carbon was satisfactory. The treated water quality complied with China's drinking water guidelines. The Ames test showed that the mutagenic activities of membrane permeate water was negative. 相似文献
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《Desalination》2007,202(1-3):302-309
Both the relationship between the flux and the fouling mechanism of ultrafiltration (UF) membrane and the effects of pretreatment before reverse osmosis (RO) process on the treatment of the effluent of industrial park wastewater treatment plant (IPWTP) were investigated to examine the application of membrane processes on the water reuse treatment. For the former, the flux data was first fitted to the Hermia model to give the implication of the fouling mechanism. Then, the fouling mechanism was further identified with the aid of the SEM morphology of membrane surfaces. For the latter, the changes of both water characteristics (turbidity, TOC, conductivity, particle size distribution, and organic solute molecular weight) and membrane properties (surface zeta potential and surface morphology) before and after the treatment of membrane processes were measured. It was found that the major blocking mechanisms of UF membrane process at initial and final stage were standard blocking of pore (causing from colloid materials) and cake blocking of pore (causing from suspended particles), respectively. On the other hand, it was concluded that the permeate from 1 μm/UF/RO process was suitable for the reuse of cooling water and low pressure boiler water. 相似文献
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超滤在反渗透预处理工艺中的应用 总被引:7,自引:0,他引:7
以UF替代传统的预处理工艺,解决了RO制水系统预处理难的问题。试验结果表明:UF可把原水的SDI(或FI)指数由8-10降至接近于零,对水中的悬浮物,金属氧化物,胶体,有机物,菌类都有良好的去除效果,可完全满足RO系统对预处理水质的要求。本文重点讨论UF作为RO预处理的工艺;UF对水中杂质的脱除效果及运行性;UF膜通量的衰减规律及恢复。 相似文献
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A solid state 13C NMR study of hardened networks obtained by the reaction of blocked and nonblocked isocyanates (pMDI) with urea‐formaldehyde (UF) resins in water showed different results according to the temperature of the reaction. At high temperature, in water, both a nonblocked or an emulsifiable, blocked isocyanate, appear to crosslink with UF resins through the formation both of traditional methylene bridges connecting urea to urea and of urethane bridges. The latter have been confirmed by 13C NMR to form in water by reaction of the isocyanate ? N?C?O group with the hydroxymethyl groups of the UF resin. At ambient temperature, UF/pMDI resins where the pMDI is a emulsifiable blocked isocyanate, do not appear to form urethanes to any great extent but rather to crosslink through the usual UF resin urea to urea methylene bridges. Even in this case, when urethane bridges appear to be absent, evidence of crosslinking in water through reaction of the isocyanate with the ? NH2 and ? NH? amide of the UF resin has not been observed. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 589–596, 2006 相似文献
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超滤-反渗透膜组合工艺处理电厂循环排污水 总被引:7,自引:0,他引:7
本文详细介绍了北京京丰天然气燃机联合循环电厂使用超滤-反渗透膜组合工艺处理循环水排污水。循环水排污水回用系统的最大问题是反渗透膜的污染控制问题。因为循环水排污水相对水质较差,因此对预处理技术要求较高,采用超滤膜作为预处理系统,能够很好地解决这个问题。北京京丰热电厂通过长时间的工业化运行,证明了在处理回用循环水排污水过程中,超滤作为反渗透预处理系统的可行性,也积累了该工艺处理循环水排污水用于电厂循环补充水和锅炉补给水方面的应用经验. 相似文献