• Food Science and Preservation
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• v.6 no.4
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• pp.424-428
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• 1999

The performance of a 30K polysulfone membrane for clarification of depectinized peach juice was studied Ultrafiltration of peach juice could minimize to loss of flavor and many compounds and was expected to effectively remove precipitation and suspended solid. The results showed that permeate flux increased with the increase of operating pressure and temperature. The permeate flux declined continuously as the process time increased. The values of soluble solid and titratable acidity of permeate were decreased or were at the same level, the turbidity was largely decreased. Total resistance decreased with lower temperature and lower pressure.

• Journal of the Korean Chemical Society
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• v.63 no.4
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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.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.6
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• pp.581-589
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• 2005

Recently, membrane processes have been replacing the conventional processes for waste water treatment to produce better quality of effluent and to meet more stringent regulations because of water shortage. However, using membrane processes for water treatment has confronted with fouling and difficulty in treating dissolved organic pollutants. In this study, membrane process equipped with crossflow microfiltration is combined with coagulation process using alum and PAC to improve permeability and treatment efficiency. The effects of coagulant dosage and optimum membrane operating conditions were investigated from measurement of permeate flow, cumulative volume, total resistance, particle size, dissolved organic pollutant, dissolved aluminium and quality of effluent. Characteristic of PAC coagulation was compared with that of alum coagulation. PAC coagulation reduced membrane fouling because of forming larger particle size and increased permeate velocity and cumulative volume. Less dissolved organic pollutants and dissolved aluminum made decreasing-rate of permeate velocity being lowered. At using $0.2\;{\mu}m$ membrane, cake filtration observed. At using $0.45\;{\mu}m$ membrane, there was floc breakage due to shear stress occurred born circulating operation. It made floc size smaller than membrane pore size, which subsequently to decrease permeate velocity and to increase total resistance. The optimum coagulation dosage was $300{\pm}50\;mg/L$ for both alum and PAC. PAC coagulation was more efficiently used with $0.2\;{\mu}m$ membrane, and the highest permeate flux was in using $0.45\;{\mu}m$membrane. The greatest efficiency of treatment was as follows; turbidity 99.8%, SS 99.9%, $BOD_5$ 94.4%, $COD_{Cr}$ 95.4%, T-N 54.3%, T-P 99.8%.

• Membrane Journal
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• v.18 no.1
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• pp.26-34
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• 2008

In this study, periodic water-back-flushing using permeate water was performed to minimize membrane fouling and to enhance permeate flux in advanced water treatment system by ceramic microfiltration. We investigated effect of water-back-flushing period (FT) and time (BT), and tried to find the optimal operating conditions. BT was fixed at 3 sec and FT was changed in $30{\sim}120$ sec to inspect effect of FT. Also, FT was fixed at 120 sec and BT was changed as $3{\sim}12$ sec at experiment of BT effect. At both two experiments, TMP was fixed at 1.52 bar, water-back-flushing pressure at 0.98 bar, feed flow rate at 0.5 L/min, and feed water temperature at $20^{\circ}C$. As the result, optimal FT was 30 sec at fixed BT 3 sec in our experimental range. It means that the more frequent back-flushing was the more effective to reduce membrane fouling. However, there were not large effects of FT due to a short BT. Then, increasing BT at fixed FT 120 sec could decrease resistance of membrane fouling ($R_f$) and increase permeate flux (J) and dimensionless permeate flux ($J/J_o$), and the most total permeate volume ($V_T$) could be produced at the maximum BT 12 sec.

• Membrane Journal
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• v.15 no.4
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• pp.338-348
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• 2005

The permeate flux decline on microfiltration capillary membrane operation was investigated with inorganic colloidal solutions. The permeate flux of the alumina solution is two times higher in average than that of the bentonite solution. The flux decline with increase in operation time was less in the alumina solution than in the bentonite solution. The rate of initial flux decline until 10 min was higher on the bentonite solution over the alumina solution. The decline in permeate flux was due to both the cake formation and the pore blocking. The latter effect was higher in the operation of the bentonite solution. In comparing the ratio of each fouling component to the total fouling fur the $1.0\;kg_f/cm^2$ TMP condition, complete blocking was $9.35\%$, standard blocking was about $6.82\%$ and cake filtration was $83.83\%$, respectively. With the increase in cross flow velocity, the permeate flux increased by $6.0\%$ for the alumina solution and by 14.0 for the bentonite solution. With the increase in average pore size fromm $0.24\;{\mu}m\;to\;0.34\;{\mu}m$, the permeate flux increases 1.61 times for the alumina solution and 1.76 times far the bentonite solution.

• Journal of the Korean Society for Marine Environment & Energy
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• v.17 no.1
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• pp.13-19
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• 2014

The feed temperature has an effect on the performance during desalination of seawater by membrane separation. When the permeate flux intends to increase using the waste heat, it is necessary to analyze the effect of feed temperature precisely on the membrane performance. The experiments were carried out to investigate the performance of membranes by varying the seawater temperature from $10^{\circ}C$ to $60^{\circ}C$. The increase of permeate flux with increase of feed temperature was interpreted as the change of water viscosity and the membrane itself. While the increase of permeate flux could be predicted by the viscosity change in case of nanoflitration membrane, there exists 30% difference between the experiment data and the prediction by the viscosity change in case of reverse osmosis (RO) membrane, which seems to be due to 8% decrease of the pore size in 60caused by the contraction of membrane with the increase of temperature. Therefore, the desalination of seawater should be carried out within the range that the elevation of temperature does not cause the alteration of membrane itself even for the purpose of increasing the permeate flux.

• Membrane Journal
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• v.29 no.3
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• pp.147-154
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• 2019

The permeate flux increments of a natural convection instability flow (NCIF) caused by the change of inclined angles ($0{\sim}180^{\circ}$) to gravity of the commercial membrane module were tested in the dead-end membrane filtration of BSA protein solution. The NCIF are more generated as the inclined angle increased from $0^{\circ}$ to $180^{\circ}$, and the occurred NCIF enhances permeate flux. However, the commercial module can only generate NCIF by completely removing the air gap in module. Since the custom design module designed in this study is permeated in a crossward direction ($90^{\circ}$), NCIF is always generated even if there is the air gap in module. The results of membrane filtration of BSA and dextran solutions using a custom design module showed that the flux in the crossward direction is increased to about 3.8 times for BSA solution and 1.8 times for dextran solution after two hours of operation due to the occurrence of NCIF. Also, NCIF generation is continued during 20 hours filtration of BSA solution, increasing the permeate flux to about 7.5 times. Since the custom design module with a permeation in the crossward direction and NCIF is always generated within the module, so it is possible to expect an increase in permeate flux due to the suppression of fouling formation, and thus to be utilized as a superb dead-end membrane module.

• Membrane Journal
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• v.10 no.4
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• pp.186-191
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• 2000

The recovery of three ethyl esters (aroma model compounds; ethyl acetate, ethyl propionate. ethyl butyrate) from aqueous solutions was studied for vapor permeation with surface-modified hydrophobic alumina membrane, Although the driving force of ethyl butyrate is the highest, the ethyl butyrate concentration in permeate is lower than those of propionate and acetate. Since the solubility of aroma compounds for water is very low, phase separation occurred in permeate, and we could obtain pure ethyl esters. The experimental results showed that the porous hydrophobic alumina membrane had high selectivity and permeation flux on the ester-model compounds.

• Korean Chemical Engineering Research
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• v.52 no.6
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• pp.775-780
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• 2014

Micellar enhanced ultrafiltration (MEUF) was used to remove cadmium from an aqueous solution using sodium dodecyl sulfate (SDS) as a surfactant. Operational parameters such as initial permeate flux, retentate pressure, initial cadmium concentration, pH solution, molecular weight cut-off (MWCO), and molar ratio of cadmium to SDS were investigated. Removal efficiency of cadmium from an aqueous solution increased with an increase of retentate pressure, pH solution and molar ratio of cadmium to SDS, and decreased with an increase of initial permeate flux. Higher removal efficiency of cadmium from the aqueous solution was achieved using lower MWCO (smaller membrane pore size). Under optimized experimental condition, cadmium removal efficiency reached 74.6 % within an hour. Using MEUF-ACF hybrid process the removal efficiency of both cadmium and SDS was found to be over 90%.

• KSBB Journal
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• v.13 no.3
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• pp.308-311
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• 1998

A novel process was developed to simultaneously produce invertase and yeast extract from baker's yeast using ultrafiltration (UF) and microfiltration (MF) membrane processing. After the extraction of invertase under the optimal condition obtained in this study, invertase was separated from yeast cells using a hollow fiber membrane with a pore size of 0.1 $\mu\textrm{m}$. The resulting permeate containing invertase was concentrated using a hollow fiber membrane with a nominal molecular weight cut-off of 30 kDa. The yeast cell and permeate solutions, which were obtained after MF and UF membrane processing, respectively, were mixed together, and the autolysis was performed at 50$^{\circ}C$ in the presence of 5% (w/v) ethanol and 1% (w/v) NaCl. As a result, the yeast extract and invertase could be simultaneously produced from baker's yeast by this novel process.