• 멤브레인
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• 제14권3호
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• pp.192-200
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• 2004

본 연구에서는 유기질막에 비해 안정성이 우수하고 사용수명이 긴 세라믹 막을 이용하여 혐기성 Lactobacillus 균주의 농축에 관해서 연구하였다. Cell harvesting (CH)에 영향을 주는 인자로 막투과 압력, 온도, 선속도 등에 대해 조사하였으며 세라믹 막을 이용하여 농축율 변화에 따른 플럭스와 TMP (transmembrane pressure)의 변화, 일정 VCF(volumetric concentration factor)에서 TMP변화 등의 최적조건에 관해 알아보았다. 그 결과 플럭스는 TMP, 선속도, VCF가 증가함에 따라 투과수량도 증가함을 알 수 있었다. 온도가 증가할수록 점도에 의해 초기 플럭스도 증가하지만 시간이 경과함에 따라 막 표면의 겔층의 형성으로 온도의 영향은 미미하였다. 또한 농축비 이하의 일정한 VCF에서 운전할 경우 플럭스가 안정적임을 알 수 있었다. 선속도 5 m/s, 공급액의 온도 $37^{\circ}C$, TMP 1 bar에서 6∼8 h 운전할 경우 PS 406 원액의 생균수는 4.9{\times}10^9$으로 약 8배 농축됨을 알 수 있었다.

• 상하수도학회지
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• 제31권2호
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• pp.169-175
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• 2017

This study applied microbubbles to reduce membrane fouling in wastewater reuse membrane processes, evaluated and compared the transmembrane pressure with or without the application of microbubbles and the cleaning efficiency with the application of aeration and microbubbles. In addition, this study analyzed foulants removed from the membrane surface. Changes in the transmembrane pressure of membranes with the presence or absence of microbubbles were observed. As a result, transmembrane pressure (TMP) increasing rate decreased twofold when applying microbubbles to realize stable operations. This study compared and evaluated cleaning efficiency applying aeration and microbubbles. As a result, the cleaning efficiency was 5% higher on average when applying microbubbles. In turbidity and total organic carbon (TOC), foulants were discharged when applying microbubbles twice as much as applying aeration. It is thought that particulate foulants precipitated on the membrane surface were more likely to desorb because the adhesion between the membrane surface and particle was weakened by microbubbles. Therefore, it is considered possible to effectively control membrane fouling because of the increase in cleaning efficiency when applying microbubbles to wastewater reuse membrane processes.

• 대한화학회지
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• 제63권4호
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• pp.260-265
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• 2019

Alcohol dehydrogenase (ADH) (EC 1.1.1.1) was selected as the enzyme which will be immobilized on ultrafiltration membrane by fouling with different transmembrane pressure of 1, 2 and 3 bars. ADH will catalyze formaldehyde (CHOH) to methanol ($CH_3OH$) and simultaneously oxidized nicotinamide adenine dinucleotide (NADH) to $NAD^+$. The concentration of enzyme and pH are fixed at 0.1 mg/ml and pH 7.0 respectively. The objective of the study focuses on the effect of different transmembrane pressure (TMP) on enzyme immobilization in term of permeate flux, observed rejection, enzyme loading and fouling mechanism. The results showed that at 1 bar holds the lowest enzyme loading which is 1.085 mg while 2 bar holds the highest enzyme loading which is 1.357 mg out of 3.0 mg as the initial enzyme feed. The permeate flux for each TMP decreased with increasing cumulative permeate volume. The observed rejection is linearly correlated with the TMP where increase in TMP will cause a higher observed rejection. Hermia model predicted that at irreversible fouling with standard blocking dominates at TMP of 3 bar, while cake layer and intermediate blocking dominates at 1 and 2 bar respectively.

• 한국환경과학회지
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• 제9권2호
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• pp.173-176
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• 2000

This study was carried out to investigate the filtration characteristics of membrane modules according to hollow fiber dispersion for direct solid-liquid separation of activated sludge. 2 bundle, 4 bundle, and 10 bundle, and 10 bundle module used in this experiment according to hollow fiber dispersion was manufactured at laboratory and permeate flux and transmembrane pressure(TMP) of each module were observed under a suction pressure of 0.5kgf/c$m^2$. As the hollow fibers were dispersed, permeate flux was increased and TMP was decreased. Permeate flux and TMP of each module was 15.0 $\ell$/$m^2$.h and 31.8 cmHg for 2 bundle, 16.0 $\ell$/$m^2$ .h and 17.4 cmHg for 4 bundle, and 20.4 $\ell$/m2 .h and 31.8 cmHg for 10 bundle. In conclusion, the membrane fouling is expected to be decrease by maintaining lower TMP with hollow fiber dispersion.

• 멤브레인
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• 제7권2호
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• pp.84-94
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• 1997

Hollow fiber의 diameter와 curvature 및 turn수 등의 변화에 따른 첫번째 모듈 set와 두번째 모듈 set 사이의 성능비교가 이루어졌다. 모든 실험들은 같은 transmembrane pressure와 막면적당 에너지 소모하에서 수행되었다. 첫번째 모듈 set에 대해서 Dean vortices에 의한 농도분극과 막오염현상의 감소시키는 효과가 매우 작음을 알 수 있었다. 두번째 모듈 set에 대해서 115%의 투과 flux 향상값 (투과 flux 증분 ${\times}100$/선형 모듈의 투과 flux)을 보였다. 이로부터 두번째 모듈 set가 yeast suspension에 의한 농도분극과 막오염현상의 감소에 훨씬 효과적임을 알 수 있었다.

• Membrane and Water Treatment
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• 제1권4호
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• pp.273-282
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• 2010

Treatment and reuse of industrial wastewater is becoming a major goal due to water scarcity. This may be carried out using membrane separation technology in general and reverse osmosis (RO) in particular. In the current study, polyamide (FT-30) membrane was employed for treatment of wastewater obtained from Faraman industrial zone based in Kermanshah (Iran). The effects of operating conditions such as transmembrane pressure, cross flow velocity, temperature and time on water flux and rejection of impurities including COD by the membrane were elucidated. The aim was an improvement in membrane performance. The results indicate that most of the chemical substances are removed from the wastewater. In particular COD removal was increased from 64 to around 100% as temperature increased from 15 to $45^{\circ}C$. The complete COD removal was obtained at transmembrane pressure of 20 bars and cross flow velocity of 1.5 m/s. The treated wastewater may be reused for various applications including makeup water for cooling towers.

• 한국막학회:학술대회논문집
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• 한국막학회 2000년도 춘계 총회 및 학술발표회
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• pp.47-50
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• 2000

• Membrane and Water Treatment
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• 제1권4호
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• pp.253-271
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• 2010

A theoretical study for the flux enhancement by pulsation of transmembrane pressure is presented for osmotic pressure controlled ultrafiltration under laminar flow regime. The transient velocity profile is solved analytically using Green's function method. Time dependent convective diffusive equation is solved to quantify the membrane surface concentration and the permeate flux, numerically. The effects of the amplitude and frequency of pulsation on flux, surface concentration and observed retention are studied.

• 상하수도학회지
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• 제18권5호
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• pp.588-597
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• 2004

In this research, we investigated the variation of transmembrane pressure and permeate water quality with pre coagulation and sedimentation with iron based coagulant and chlorination of feed water for PVDF (polyvinylidene fluoride) based MF membrane filtration. NaCIO was fed to the membrane module with dosage of 0.5mg/L and maintained during filtration. To observe the effect of raw water, three types of raw and processed waters, including river surface water, coagulated water and coagulated-settled water, were applied. In case of river surface water, the transmembrane pressure increased drastically in 500 hours of operation. On the contrary, no significant increase in transmembrane pressure was observed for 1,200 hours of operation for coagulated water and coagulated-settled waters. The turbidity of permeate was lower than a detection limit of equipment for all raw waters. The removal efficiency of humic substances of coagulated water and coagulated-settled water was approximate ten times of that of surface river water. And, the removal efficiency of TOC and DOC was approximate two times of that of surface river water. From the results of plant operation, stable operation was maintained at $0.9m^3/m^2{\cdot}day$ filtration flux through the combination of pre-coagulation and pre-chlorination. However, the water quality of permeate was the best when pre-coagulation-sedimentation process was combined with pre-chlorination.

• Membrane and Water Treatment
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• 제6권1호
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• pp.77-94
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• 2015

Ultrafiltration membranes have several advantages over conventional drinking-water treatment. However, this technology presents major limitations, such as irreversible fouling and low removal of natural organic matter. Fouling depends heavily on the raw-water quality as well as on the operating conditions of the process, including flux, permeate recovery, pre-treatment, chemical cleaning, and backwashing. Starting with the premise that the optimisation of operating variables can improve membrane performance, different experiments were conducted in a pilot plant located in Granada (Spain). Several combinations of permeate and backwashing flow rates, backwashing frequencies, and aeration flow rates were tested for low-quality water coming from Genil River with the following results: the effluent quality did not depend on the combination of operating conditions chosen; and the membrane was effective for the removal of microorganisms, turbidity and suspended solids but the yields for the removal of dissolved organic carbon were extremely low. In addition, the threshold transmembrane pressure (-0.7 bar) was reached within a few hours and it was difficult to recover due to the low efficiency of the chemical cleanings. Moreover, greater transmembrane pressure due to fouling also increased the energy consumption, and it was not possible to lower it without compromising the permeate recovery. Finally, the intensification of aeration contributed positively to lengthening the operation times but again raised energy consumption. In light of these findings, the feasibility of ultrafiltration as a single treatment is questioned for low-quality influents.