• 상하수도학회지
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• 제19권6호
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• pp.775-780
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• 2005

This study was performed to investigate the effect of foulant characteristics on Membrane fouling index such as Silt Density Index (SDI) and Modified Fouling Index (MFI). A linear relationship was found relating the fouling index (both SDI and MFI) on particle concentration, but fouling index values were nonlinearly (exponentially) with increasing organic concentration. When organic matter was the primary cause of fouling, the MFI was not accurately predicted due to internal fouling such as pore adsorption. The fouling index was determined mainly by particle characteristics when both particle and organic coexisted in the feed water. This observation was attributed to lessening of organic pore adsorption by particle cake layer formed on the membrane surface. Bench-scale actual fouling experiments demonstrated that permeate flux declines much faster with feed water containing particles than organic matters although fouling potential predicted by SDI values were identical, indicating that the accurate prediction of fouling potential requires the development of fouling index reflecting different foulant characteristics.

• Membrane and Water Treatment
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• 제6권2호
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• pp.161-172
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• 2015

Forward osmosis (FO) is an emerging membrane technology with potential applications in desalination and wastewater reclamation. The osmotic pressure gradient across the FO membrane is used to generate water flux. In this study, flux performance and foulant deposition on the FO membrane were systematically investigated with a co-current cross-flow membrane system. Sodium alginate (SA), bovine serum albumin (BSA) and tannic acid (TA) were used as model foulants. Organics adsorbed on the membrane were peeled off via oscillation and characterized by Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM). When an initial flux of $8.42L/m^2h$ was applied, both flux reduction and foulant deposition were slight for the feed solution containing BSA and TA. In comparison, flux reduction and foulant deposition were much more severe for the feed solution containing SA, as a distinct SA cake-layer was formed on the membrane surface and played a crucial role in membrane fouling. In addition, as the initial SA concentration increased in FS, the thickness of the cake-layer increased remarkably, and the membrane fouling became more severe.

• 상하수도학회지
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• 제16권6호
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• pp.717-725
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• 2002

A bench-scale submerged-type membrane filtration system (SMFS) was constructed to study a feasibility of membrane filtration for solid-liquid separation in water and wastewater treatment processes. In the case of applying the SMFS to a biological wastewater treatment process, so-called membrane bioreactor, aeration underneath membrane modules is usually employed in order to provide oxygen demand for microbial growth as well as to control membrane fouling. A study was investigated the effects of operation parameters by aeration intensity, feed concentration, foulant type and airlift pore size on critical flux. Critical flux tends to increase with aeration rate. Optimal aeration flow rate was found to be 10 L/min/module. Feed concentration and foulant type has a significant effect on membrane fouling and filtration performance. But downward position and pore size of airlift has no a significant effects on membrane fouling and filtration performance.

• 멤브레인
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• 제12권2호
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• pp.55-66
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• 2002

본 총설에서는 전기투석 공정의 운전과 설계 능력 향상을 위해 이온교환막의 막오염현상에 관한 연구를 조사하였다. 이온교환막의 막오염현상을 정량적으로 평가하기 위해 압력차를 구동력으로 하는 막공정의 막오염지수와 유사한 전기투석 막오염지수(EDMFI)를 정의하였다. 막오염현상은 무기오염원인 실리카졸과 유기 오염원인 휴믹산과 BSA를 함유한 전기 투석 실험 결과를 비교하여 연구되었다. 이 비교에서 EDMFI는 전기투석 공정의 막오염경향을 정량적인 척도로 유용하게 이용될 수 있음을 보여주었다. 새로운 오염저감 기술로 사각파 전원이 유효함이 유기 오염물을 포함한 전기투석 실험결과에서 보고되었다. 이펄스 형태의 사각파 전원은 최적주파수에서 막오염현상을 현저하게 감소시킬 수 있었다.

• 한국물환경학회지
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• 제18권2호
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• pp.159-168
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• 2002

A lab-scale Reverse Osmosis(RO) membrane reactor was installed to investigate the membrane permeability, characteristics of membrane fouling at each conditions, and performance of elimination at different trans-membrane pressure(TMP) in the liquid fertilizer accumulated system. Experimental setup was divided to three different TMP conditions. As a result of experiment, permeability of RO membrane was proportional to the increase of TMP and temperature. After experiment was completed, two types chemical cleaning(remove the organic foulant and inorganic foulant) was done, and recover rate of permeability was each 99.8, 99.7 and 99.7%, respectively. From this experimental data, membrane fouling could be determined that the most of it was recoverable in this system, and major reason of fouling was concentration polarization. Elimination rate of solute substance in the liquid fertilizer indicated very stable(above 99%), except ammonia nitrogen, and the most stable elimination rate was investigated at the highest TMP condition (Run 3).

• 한국물환경학회지
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• 제27권1호
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• pp.44-53
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• 2011

Membrane bio-reactor (MBR) has several advantages over the conventional activated sludge process, including a high biomass, low sludge production, and better permeate quality. Therefore, the MBR have gained popularity for municipal and industrial wastewater treatment. However the MBR usually were used for sewage and low streng th wastewater treatment because of membrane fouling problem and limitation of oxygen transfer into biomass. In this study, the hybrid process combining MBR and pure oxygen was tested for high strength organic wastewater treatment in the COD loading range from 2 to $10kgCOD/m^3{\cdot}day$. The hybrid process, membrane coupled pure oxygen high compact reactor (MPHCR), had been operated for one year and operation parameters, the effect of COD loading, MLSS concentration and the location of membrane module were studied for membrane fouling characteristic. Also membrane resistance test and the component of foulant was analyzed to investigate what is specific foulant in the MBR.

• 대한환경공학회지
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• 제22권12호
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• pp.2205-2213
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• 2000

NF와 RO를 이용한 용존성 물질의 제거특성을 관찰하기 위해 UF로 전처리된 지하수가 파일럿플랜트에 6개월 동안 연속 공급되었다. 그리고 NF와 RO에서 발생한 막 오염의 특성을 파악하고 막 오염물질을 규명하기 위해서 파일럿플랜트에서 NF와 RO를 분리하여 autopsy test를 실시하였다. Autopsy test에서는 파일럿플랜트에서 사용된 막의 투과플럭스와 화학세정에 따른 플럭스의 회복율을 측정하였다. 아울러 여기서 발생한 폐세정액의 수질을 분석하여 막 오염물질의 구성성분을 알아보고자 하였다. NF와 RO1의 비플럭스는 운전시간 100일 이후에 급격히 감소하기 시작하였고 RO1에서의 감소율이 NF에서보다 컸다. 회수율이 낮온 RO2의 비플럭스는 점진적으로 감소하였다. 파일럿플랜트에서 용존성 무기물질의 제거율은 전기전도도로 NF, RO1, RO2 막에서 각각 76.3%, 88.2%, 95.3%로 RO2에서 가장 높았다. 용존성 유기물질의 제거율은 TOC로 80%정도였다. 와권형 NF와 RO의 막 오염은 원수 유입부보다는 농축수 유출부에서 많이 발생하였다. 이것은 유출부로 갈수록 막면선속도가 낮아지고 원수 중 오염물질의 농도가 높아졌기 때문이다. 막 오염물질의 주성분은 무기성 Ca염과 유기성 Si염인 것으로 생각되며 비가역적 막 오염에 기여도가 가장 큰 물질은 Fe인 것으로 생각된다. 막 오염물질의 형상을 SEM으로 관찰한 결과 최근접 표면에 유기물질이 부착되어 있고 그 위에 판상모양의 무기성분이 쌓여 있는 형태가 관찰되었다. 미생물 막 오염은 거의 관찰되지 않았는데 이것은 UF에서 1차로 대부분의 미생물이 제거되었기 때문이다.

• 상하수도학회지
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• 제21권5호
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• pp.559-569
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• 2007

The purposes of this study were to find the main foulant of membrane and the optimal chemical cleaning method for MF(microfiltration) drinking water treatment system using D dam water as water source. The MF pilot plant which can treat maximum $500m^3/d$ consisted of 3 racks and was operated for 10 months under various operation conditions. After 10 months operation, $1^{st}$ and $2^{nd}$ rack of membrane pilot plant system were cleaned chemically and the degree of the restoration of the fouled membrane in terms of the pure water flux was detemnined. Inorganic compounds which contained in chemical cleaning waste was analyzed by Inductively Coupled Plasma (ICP). One membrane module for 3rd rack was disjointed and membrane fouling materials, especially inorganic compounds were investigated by Electron Probe Microanlysis (EPMA) to elucidate the reason of TMP increase. And also, the various chemical reagents (1N HCl or $H_2SO_4$, oxalic acid as acid and 0.3% NaOCl as alkali) were tested by combination of acid and alkali to determine the optimal chemical cleaning method for the MF system using micro-modules manufactured using the disjointed module. It was verified that the inside and outside of membrane module was colorized with black. As a result of the quantitative and semi-qualitative analysis of membrane foulant by ICP, most of inorganic foulant was manganese which is hard to remove by inorganic acid such as HCI. Especially, it was observed by EPMA that Mn was attached more seriously in inside surface of membrane than in outside surface of that. It was supposed that Mn fouling in inside surface of membrane might be caused by the oxidation of soluble manganese (Mn(II)) to insoluble manganese ($MnO_2$) by chlorine containing in backwashing water. The optimal cleaning method for the removal of manganese fouling was consecutive cleaning with the mixture of 1N HCl and 1% of oxalic acid, 0.3% NaOCl, and 1N HCl showing 91% of the restoration of the fouled membrane.

• 멤브레인
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• 제21권2호
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• pp.171-176
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• 2011

분리막을 이용한 수처리 공정에서 유입 수에 함유된 부유물질이나 기타 오염물질이 막 표면 또는 내부에 축적 흡착 등의 막 오염현상으로 인해 막 성능 감소와 함께 막 분리 공정에 큰 영향을 미치게 된다. 본 연구에서는 막 표면에서의 막 오염현상을 실시간으로 모니터링 할 수 있는 기술을 연구하였다. 투명한 오염물질에 의한 분리막 표면 오염을 측정하기 위해 막 표면에 360 nm 파장의 가시광선을 조사하여 이미지를 R. G. B 값으로 추출하여 막의 오염현상을 실시간으로 모니터링 하였다. 추출된 이미지 중 400~499 nm 파장영역인 B 값이 가장 강도가 강하게 나타났다. 막 오염정도의 변화를 이미지의 강도 차이로 관찰함으로써 실시간 분석이 가능함을 확인하였다.

• Environmental Engineering Research
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• 제11권2호
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• pp.91-98
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• 2006

There is a possibility of the production of the air bubbles in membrane pores due to the reduction in pressure during membrane filtration. The effect of fine air bubbles from dissolved gases on microfiltration was investigated in the submerged membrane bio-reactor (SMBR). The $R_{air}$ (air bubble resistance) was defined as the filtration resistance due to the air bubbles formed from the gasification of dissolved gases. From the results of filtration tests using pure water with changes in the dissolved oxygen concentration, the air bubbles from dissolved gases were confirmed to act as a foulant and; thus, increase the filtration resistance. The standard pore blocking and cake filtration models, SPBM and CFM, respectively, were applied to investigate the mechanism of air bubble fouling on a hollow fiber membrane. However, the application of the SPBM and CFM were limited in explaining the mechanism due to the properties of air bubble. With a simple comparison of the different filtration resistances, the $R_{air}$ portion was below 1% of the total filtration resistance during sludge filtration. Therefore, the air bubbles from dissolved gases would only be a minor foulant in the SMBR. However, under the conditions of a high gasification rate from dissolved gases, the effect of air bubble fouling should be considered in microfiltration.