• Membrane Journal
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• v.3 no.1
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• pp.35-39
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• 1993

Reverse osmosis(RO) and pervaporation(PV) membrane separation proceaes were compared with each other experimentally for the system of water-ethanol mixtures by using nylon 4 blended membranes. The separation effciencies of PV were better than those of RO as expected in previous paper covering the theoretical comparisons of both processes, however tbe permeabilities data showed erraerie results due to the membrane imperfections.

• Journal of Korean Society of Water and Wastewater
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• v.23 no.1
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• pp.31-37
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• 2009

Low-pressure membrane processes have been extensively expanded their applications to drinking water production in a few decades. As a capacity of a membrane plant becomes greater in recent years, proper methods to increase water production as well as to treat residuals have drawn great attention. A possible treatment option for the better water production is to apply a dual membrane system. The second stage microfiltration was installed and operated for approximately six months. The residuals from the two stage microfiltration were investigated to learn their characteristics in settling and dewatering processes. The settlability of the membrane residuals were greatest at the SS concentration of approximately 15000mg/L. The proper dose of the polyelectrolytes for filterability were obtained in the range of 0.5~1%. In the dosage range, the water contents of the membrane residuals were greater but the SRF were lower than the residual from the conventional process.

• Membrane Journal
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• v.1 no.1
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• pp.100-100
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• 1991

A novel system to thicken the concentrated colloidal solution from membrane water treat-ment processes was developed. A hollow-fiber microfilter(hydrophilic polyethylene nominal pore size 0.1 μm total surface area 0.42 m2) was installed in an acrylic housing that has an aeration port 5 cm below the membrane and a clarifier in the bottom. The concentrate was uniformly supplied from the top of the housing. Bacuum filtration caused downward flow of concentrate and as a result thickening interface. The addition of poly-aluminum chloride (PAC) resulted in rapid increase of trans-membrane pressure (TMP) and in no improvement of the filtered water turbidity and thickening process. Two types of con-centrate and concentrate turbidity had little effect on the increase of TMP and concentrate thickening. It was observed that for the same height of membrane housing membrane surface area to housing volume (A/V) ratio had significant effect on the increase of TMP. When the housing volume was increased ten times the increasing rate of TMP was three times faster as compared to the original housing. A hydraulic model successfully simulated the formation and sedimentation of thickening interface.

• Journal of Korean Society of Water and Wastewater
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• v.30 no.4
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• pp.417-425
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• 2016

Desalination is a key technology to overcome water shortage problem in a near future. High energy consumption is an Achilles' heel in desalination technology. Osmotically driven membrane processes like forward osmosis(FO) was introduced to address this energy issue. Characterizing membrane properties such as water permeability(A), salt permeability(B), and the resistance to salt diffusion within the support layer($K_{ICP}$) are very important to predict the performance of scaled-up FO processes. Currently, most of researches reported that the water permeability of FO membrane was measured by reverse osmosis(RO) type test. Permeating direction of RO and FO are different and RO test needs hydraulic pressure so that several problems can be occurred(i.e. membrane deformation, compaction and effect of concentration polarization). This study focuses on measuring water permeability of FO membrane by FO type test results in various experimental conditions. A statistical approach was developed to evaluate the three FO membrane properties(A, B, and $K_{ICP}$) and it predicted test result by the internal and external concentration polarization model.

• Membrane Journal
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• v.20 no.4
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• pp.267-277
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• 2010

Gas separation membranes have been developed for decades in various areas to replace the conventional processes. Membrane processes for gas separation have many advantages of energy saving, compact size, and easy scale-up. Nowadays, gas separation processes is widely spreaded in nitrogen generating system, hydrogen generating system, membrane dryer, on board inert gas generating system, natural gas purification, biogas purification and fuel cells. Carbon dioxide separation process using membrane would be a strong candidate of carbon dioxide capturing process. In order to broaden the scope of application of gas separation membranes, development of new materials which can overcome the borderline of Robeson's plot should be necessary, so that many researchers and companies are trying to develop the new materials like polymers containing cardo and spiro group and PIMs (polymers for intrinsic microporosity).

• Proceedings of the Membrane Society of Korea Conference
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• 2003.07a
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• pp.37-40
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• 2003

Mesoporous zeolite - heteropolyacid-polymer hybrid membrane was prepared by sol-gel processes to make a proton conducting membrane. The crystallinity of mesoporous zeolite in composite membrane was increased with contents of heteropolyacid. Proton conductivity obtained from impedance measurements increases with contents of heteropolyacid, about 10$^{-3}$ S/cm in ca. 1.5 Wt% heteropolyacid.

• Proceedings of the Membrane Society of Korea Conference
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• 2004.05a
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• pp.25-28
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• 2004

In recent years, membranes have become fully or partially integrated into all facilities that produce drinking water since membrane processes can resolve technically complex and, at times, conflicting requirements related to compliance with multi-contaminant regulations. However, NF or RO technologies are hydraulically limited by the feed water quality that causes the fouling in a membrane system. In particular, NF or RO systems involved in surface water treatment generally require extensive pretreatment for controlling membrane fouling.(omitted)

• Membrane Journal
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• v.1 no.1
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• pp.78-95
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• 1991

Water factory 21(WF 2) in Orange County California, is a advanced wastewater treatment(AWT) plant designed to reclaim biologically treated munidpal wastewater for injection into a seawater barrier system. Processes included are lime treatment air stripping, filtration, activated carbon adsorption, reverse osmosis(RO), and chlorination. The effectiveness of each treatment process is presented including pretreatment, RO dimineralization. The data collected show that the processes, including RO, used at WF-21 are capable of producing a very high quality water on a reliable basis. Treatment reduced all contaminants, to levels below national primary drinldng water regulation maximum contaminant levels. It was found that lime clarified secondary effluent can be used as feedwater to a RO dimineralizer. Experiments with new low pressure membrane(250psi) show great potential for reducing RO cost.

• Membrane and Water Treatment
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• v.3 no.4
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• pp.221-230
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• 2012

This study employed the modified fouling index (MFI) to determine the performance of a two-step recycling system - a membrane filtration integrated laminar flow water storage (LFWS) tank followed by an ion exchange process to reclaim ultrapure water (UPW) from the wastewater generated from semiconductor wafer backgrinding and sawing processes. The first step consisted of the utilization of either ultrafiltration (UF) or nanofiltration (NF) membranes to remove solids in the wastewater where the second step consisted of an ion exchanger to further purify the filtrate. The system was able to produce high purity water in a continuous operating mode. However, higher recycling cost could be incurred due to membrane fouling. The feed wastewater used for this study contained high concentration of fine particles with low organic and ionic contents, hence membrane fouling was mainly attributed to particulate deposition and cake formation. Based on the MFI results, a LFWS tank that was equipped with a turbulence reducer with a pair of auto-valves was developed and found effective in minimizing fouling by discharging concentrated wastewater prior to any membrane filtration. By comparing flux behaviors of the improved system with the conventional system, the former maintained a high flux than the latter at the end of the experiment.

• Membrane Journal
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• v.23 no.4
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• pp.304-311
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• 2013

In fermentation-separation processes, nanofiltration membrane processes can be used to separate organic acid and other byproducts such as sugars and proteins. In this study, new nanofiltration membranes were prepared to improve organic acid permeability during the separation processes of fermentation broth. Positively charged nanofiltration membrane was introduced to reduce lactic acid rejection by electrostatic attraction between lactic acid and nanofiltration membrane. Newly fabricated nanofiltration membranes were prepared by grafting cationic polyelectrolyte, PEI, on membrane surface. Thenanofiltration membranes showed positively charged surface potential. As a result, lactic acid rejection was remarkably reduced while the rejection of glucose was not changed significantly.