• Title/Summary/Keyword: reverse osmosis membrane

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Evaluation of Microfiltration Membrane as Prefilter for Reverse Osmosis membrane (역삼투막의 전처리를 위한 정밀여과막의 평가)

  • hong, Seongho;Oh, Seoukhwan;Jeon, Jaehong
    • Clean Technology
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    • v.7 no.3
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    • pp.179-185
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    • 2001
  • Some companies are trying to develop the microfiltration membranes because most of them used as a prefilter is imported in Korea. However, they are faced with much difficulty such as characterization of membrane and controlling of pore size on development. In this study, a microfiltration membrane developed by a company was evaluated for applicability to use as a prefilter before reverse osmosis membrane process in production of ultra pure water. The optimum feed pressure for the raw water was obtained at 0.2 to 0.4 atm. At that time, turbidity of the treated water was 0.4 NTU and flux was 6,000 to $9,000L/m^2/hr$. In case of the conventionally treated water, it showed the very stable flux and turbidity at 90% of recovery rate. The chemical cleaning was helpful to reduce the TMP for treated water. The turbidity was improved from 0.3 NTU to 0.1 NTU after chemical cleaning.

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Cleaning of the Waste Reverse Osmosis Membrane Filters for the Household Water Purifier and Their Performance Enhancement Study (정수기용 역삼투 폐분리막 필터의 세정 및 성능 향상 연구)

  • Cho, Young Ju;Rhim, Ji Won
    • Membrane Journal
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    • v.27 no.3
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    • pp.232-239
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    • 2017
  • In this study, the regeneration investigation for waste reverse osmosis membrane filters which were discarded after use for the household water purifiers has been carried out. Sodium hydroxide, sodium bisulfate, and ethylenediamine tetra acetic acid(EDTA). as the chemical cleaning agents were used. And they were in-situ cleaned with the micro-bubble generator as well. The best result was obtained when both 0.1% EDTA and micro-bubbles were used for 30 min cleaning. Thus, when the performance of the brand new RO membrane and restorated RO membrane were compared, the flux, 19.9%, the recovery ratio 45% were enhanced while the salt rejection was reduced for NaCl 100 mg/L solution, in other words, it has been recovered to the original brand new RO membrane filter. Also the removal of pollutants on membrane surface was confirmed in a naked eye through the scanning electron microscopy. Finally, this research has provided the possibility of the re-use of the waste RO membrane filters of household water purifier which were reclaimed or incinerated after use.

Characterization of Reverse Osmosis Membrane Surface Modified by Silane-epoxy Using UV (UV를 적용한 역삼투막의 실란-에폭시 표면 개질 및 특성 평가)

  • Park, Hee Min;Yang, Won Yong;Lee, Yong Taek
    • Membrane Journal
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    • v.28 no.3
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    • pp.169-179
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    • 2018
  • The purposes of this paper were to improve both fouling and chlorine resistance by increasing the hydrophilicity of the reverse osmosis membrane. In order to improve chlorine resistance, the surface of RO membrane was activated by ultraviolet irradiation, and then it was modified by the sol-gel method using Octyltriethoxysilane (OcTES) such as the silane coupling agent to low sensitivity to chlorine, thereby the polyamide active layer was protected and chlorine resistance was improved. In addition, polyglycerol polyglycidyl ether (PGPE) and sorbitol polyglycidyl ether (SPE) coating with different number of epoxides, ring opening reaction of epoxide improved the anti-fouling resistance. The surface modification condition was optimized by FT-IR, XPS, and contact angle analysis. As a result, the permeability reduction rate of the silane-epoxy modified membrane after the fouling test was decreased about 1.5 times as compared with that of the commercial membrane. And the salt rejection was maintained over 90% at $20,000ppm{\times}hr$ even after chlorine resistance test.

Interpretation of Permeation Characteristics and Membrane Transport Models Through Polyamide Reverse Osmosis Membrane (Polyamide 역삼투막의 투과성능과 막 이동 모델의 해석)

  • 김노원;김영길;이용택
    • Membrane Journal
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    • v.14 no.1
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    • pp.75-84
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    • 2004
  • In this study, we present a noble study far membrane transport models using chlorine resistance of polyamide RO membranes. Membrane transport mechanism is investigated by the comparison of membrane permeation performance under the continuous and Intermittent operation modes with mixed feed solution containing NaOCl and NaCl. Analysis of permeation performance indicates that solution-diffusion model and preferential adsorption-capillary flow model are relatively efficient according to operation mode. Under the continuous flow state, mass transfer depends on preferential adsorption-capillary flow model rather than solution-diffusion model. On the other hand, it prefers solution-diffusion model to preferential adsorption-capillary flow model under the stationary state. SEM images of NaOCl treated membrane surfaces strongly support these conclusions. These surface images reveal that NaOCl treated membrane in continuous operation mode exhibits ridge and valley structure in some fraction of the surface area, whereas that in intermittent operation mode shows surface degradation entirely.

Evaluation on Chemical Cleaning Efficiency of Fouled in $1,000,000m^3/day$ Sea Water Reverse Osmosis Membrane Plant (해수용 역삼투막을 이용한 $1,000,000m^3/day$ 규모의 플랜트에서 오염된 막의 화학세정 효율 평가)

  • Park, Jun-Young;Kim, Ji-Hoon;Jeong, Woo-Won;Nam, Jong-Woo;Kim, Young-Hoon;Lee, Eui-Jong;Lee, Yong-Soo;Jeon, Min-Jung;Kim, Hyung-Soo
    • Journal of Korean Society of Water and Wastewater
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    • v.25 no.3
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    • pp.285-291
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    • 2011
  • Membrane fouling is an unavoidable phenomenon and major obstacle in the economic and efficient operation under sea water reverse osmosis (SWRO). When fouling occurs on the membrane surface, the permeate quantity and quality decrease, the trans-membrane pressure (TMP) and operation costs increase, and the membrane may be damaged. Therefore, chemical cleaning process is important to prevent permeate flow from decreasing in RO membrane filtration process. This study focused on proper chemical cleaning condition for Shuaibah RO plant in Saudi Arabia. Several chemical agents were used for chemical cleaning at different contact time and concentrations of chemicals. Also autopsy analysis was performed using LOI, FT-IR, FEEM, SEM and EDX for assessment of fouling. Specially, FEEM analysis method was thought as analyzing and evaluating tool available for selection of the first applied chemical cleaning dose to predict potential organic fouling. Also, cleaning time should be considered by the condition of RO membrane process since the cleaning time depends on the membrane fouling rate. If the fouling exceeds chemical cleaning guideline, to perfectly remove the fouling, certainly, the chemical cleaning is increased with membrane fouling rate influenced by raw water properties, pre-treatment condition and the point of the chemical cleaning operation time. Also choice of cleaning chemicals applied firstly is important.

Understanding on TDS Creep Phenomena of Reverse Osmosis Membranes in Water Purifiers (역삼투막 정수기에서 발생하는 총용존고형물 크리프 현상의 이해)

  • Kang, Sanghyeon;Yun, Sunghan
    • Membrane Journal
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    • v.32 no.2
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    • pp.126-132
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    • 2022
  • Water purifiers have a quite different characteristic in comparison with general membrane water treatment processes in which the running and resting are repeated dozens of times a day. In the case of water purifiers using reverse osmosis membranes, this characteristic makes a phenomenon that the total dissolved solids (TDS) of permeate in water purifiers at the beginning of running shows a higher value than a normal value (TDS reduction is lower than a normal value). It is called "TDS creep". The effects of resting times and feed concentrations on the TDS creep were investigated. The feed flushing, the volume increase in permeate side and the flushing with purified water were applied to reduce TDS creep and the effectiveness were observed. Among these trials, the minimization of concentration between feed and permeate side of reverse osmosis membrane like the flushing with purified water can be an ultimate solution to reduce the TDS creep.

Efficiency Estimation for Desalination System of Seawater Using Reverse Osmosis Membrane (역삼투압막 해수담수화 장치의 미네럴 분리 성능평가)

  • Moon, Deok-Soo;Jung, Dong-Ho;Kim, Hyeon-Ju;Shin, Phil-Kwon
    • Journal of the Korean Society for Marine Environment & Energy
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    • v.8 no.2
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    • pp.60-66
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    • 2005
  • When external pressure higher than osmosis pressure is reversely derived into solution, its solvent is moved into the solution having lower concentration, which is called 'reverse osmosis'. We investigated the desalination application of deep ocean water using reverse osmosis pressure of $40-70\;kgf/cm^2$ We observed how to operational factor j like flow rate, water temperature and pressure have effect on efficiency of reverse osmosis membrane and salts rejection. Fluxes of reverse osmosis membrane are directly proportional to water temperature and pressure. However, salts rejection rates are positively correlated with pressure and inversely proportional to water temperature. Separation efficiencies of osmosis membrane for major elements such as $Mg^{2+},\;Ca^{+2},\;Na^+\;and\;K^+$ are as follows in a strong electrolysis solution like seawater; $Ca^{2+},\;Mg^{2+}>K^+>Na^+$. Rejection rates of $Mg^{2+}\;and\;Ca^{2+}$ that have high electric charges are over 99% and show positively correlation with water temperature. Rejection rates of $Na^+$ having low electric charge is observed to be 98%-99%, which rates is much lower than those of $2^+$ charged ions like $Ca^{2+}\;and\;Mg^{2+}$. Ion rejection rates of boron, B, are much low because boron is present il free state or gas phase in seawater. Boron concentration in desalination water is over criteria of Korean drinking water, 0.3 mg/L. However, we could satisfied with the criteria of drinking water under the operation condition like temperature $5^{\circ}C$ and pressure $70kgf/cm^2$, using the relationship that rejection rates of boron is proportional to pressure and is inversely proportional to water temperature

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Advanced Treatment for Reuse of Oil Refinery Process Wastewater using UF/RO Processes (UF/RO 공정을 이용한 정유공장 방류수의 재활용을 위한 고도처리)

  • 이광현
    • Membrane Journal
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    • v.10 no.4
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    • pp.220-229
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    • 2000
  • Deionized water and wastewater flux were discussed using module set 1-7 composed of ultrafiltration hollow fiber type modules and reverse osmosis spiral wound type modules. The separation characteristics of ultrafiltration and reverse osmosis membranes were discussed with the variation of applied pressure and temperature. Turbidity and SS were removed effectively from ultrafiltration mem¬brane, and removal efficiency of COD, T-N, and TDS using reverse osmosis membrane was very efficient. Permeate flux increased linearly with the increase of applied pressures and temperature. It was shown that ultrafiltration and reverse osmosis membranes were suitable Lo the advanced treatment and reuse of oil refinery process effluent.

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