• Journal of Korean Society on Water Environment
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• v.21 no.3
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• pp.242-247
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• 2005

In this study, we investigated the removal efficiencies of pollutants and permeate fluxes depending on chemistry of feed water, various molecular weight cut-offs (MWCOs) and materials of membrane, operating pressure. We used seven MWCO membranes of YC0.5, YM1, YM3, YM10, YM30, YM100 and PM30, humic acid solution and surface water as feed water, and examined variation in permeate flux. Results of TOC removal experiment demonstrate that MWCO lower 1,000daltons could remove humic acid effectively. As increasing solution pH and decreasing divalent cations ($Ca^{2+}$) concentration, TOC removal increased. But $UV_{254}$ removal efficiency increased with higher divalent cation concentration and solution pH. Membrane fouling increased with increasing electrolyte (NaCl), divalent cation concentration and decreasing solution pH. In spite of initial permeate flux of the hydrophobic membrane (PM30) was higher than that of the hydrophilic membrane (YM30), flux decline of PM30 was significant during operation. At higher operating pressure, compactness of the cake layer on the membrane surface increased, resulting in gradual increase in hydraulic resistance.

• Applied Chemistry for Engineering
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• v.22 no.6
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• pp.703-710
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• 2011

As the spacer in the membrane module provide the channel space to flow the feed solution smoothly and induce the flow turbulence, it could help to reduce both the concentration polarization and to take the long-term operation of membrane modules with high permeate flux by mixing the accumulated contaminants on the membrane surface into the bulk solution. In this study, the concentration distribution in membrane module with respect to the spacers which have the cross-sectional shapes of circle, cross, diamond and hexagon, the angles of spacer configuration, solute rejection and permeate flux were interpreted and optimized numerically using the "COMSOL Multiphysics" software. The concentration on the membrane surface was kept the lowest level for the cross-shape among the above four types of spacers. Also the 30 degree spacer configuration was showed as the most efficient case. The concentrations on the membrane surface at the module outlet for without spacer and the cross shape with the 30 degree spacer configuration were 2.09 and 1.29 times higher than those at inlet, respectively. The reduction effect of concentration polarization increased rapidly as the permeate flux increased.

• 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.

• Membrane Journal
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• v.33 no.1
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• pp.34-45
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• 2023

Two computational intelligence techniques namely artificial neural networks (ANN) and support vector machine (SVM) are employed to model the permeate flux based on seven input variables including time, transmembrane pressure, rotating velocity, the pore diameter of the membrane, dynamic viscosity, concentration and density of the feed fluid. The best-fit model was selected through the trial-error method and the two statistical parameters including the coefficient of determination (R²) and the average absolute relative deviation (AARD) between the experimental and predicted data. The obtained results reveal that the optimized ANN model can predict the permeate flux with R² = 0.999 and AARD% = 2.245 versus the SVM model with R² = 0.996 and AARD% = 4.09. Thus, the ANN model is found to predict the permeate flux with high accuracy in comparison to the SVM approach.

• Journal of the Korean Ceramic Society
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• v.37 no.5
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• pp.403-409
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• 2000

The permeation characteristics and reclamation efficiency of waste lubricating oil were studied as a function of the types of ceramic composite membranes and the membrane separation process variables. The oil permeability of the TiO2 composite membrane(pore size 0.015 $\mu\textrm{m}$) was directly proportional to the crossflow velocity(0.22∼0.9 m/s) and temperature(150$^{\circ}C$∼200$^{\circ}C$). In the batch concentration process, as the concentration factor increased, both the permeability and the ash content of the permeate decreased. The average ash contents of the total permeate through the A6 alumina membrane(average pore size 0.8$\mu\textrm{m}$), Z1/A6 and Z1/A4(pore size 0.23$\mu\textrm{m}$)/A7(pore size 6$\mu\textrm{m}$) zirconia composite membrances(average pore size 0.07$\mu\textrm{m}$) were about 0.063 wt%, 0.045wt% and 0.08wt% in the region of 1∼2 concentration factor, respectively. The ash content of the mixed permeate through the A6 alumina and zirconia composite membrane was about 0.06 wt% and it can be also reduced to 0.06 wt% in the Z1/A6 membrane and below 0.003 wt% in the TiO2/Z1/A6 membrane. It was concluded that the treated oil obtained from the multi-step membrane separation process could be used as reclaimed lubricating oil as well as reclained fuel oil.

• Membrane Journal
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• v.20 no.2
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• pp.113-119
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• 2010

Biodiesel was produced from Canola, soybean and Jatropha oils combined methanol using continuously recycled membrane reactor. The membrane served to react and separate the unreacted oil from the product stream, producing high-purity fatty acid methyl ester (FAME). Two ceramic tubular membranes having different nominal pore sizes of 0.2 and 0.5 ${\mu}m$ were used. Permeate was observed at 0.5, 1.0 and 2.0 bar with a given flow rate, respectively. The permeate flux for 0.2 ${\mu}m$ membrane at 0.5 bar and 400 mL/min flow rate was 15 L/$m^2{\cdot}hr$. Also FAME content in permeate was the highest at 0.5 bar, and decreased with increasing operating pressure.

• KSBB Journal
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• v.4 no.2
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• pp.177-184
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• 1989

In separating mycelia from antibiotic fermentation broths, high permeate flux was obtained by cross-flow filtration using modified regenerated cellulose membrane. The flux was increased most effectively by increasing the flow rate. There existed a critical mycelium density (about 20% PMV) at which the highest flux was observed. In a batchwise concentration of the fermentation broth, the system suffered from a severe fouling problem, which was relieved drastically by applying diafiltration technique, although it increased the permeate volume. A combined concentration/diafiltration process was ideal in keeping relatively high flux together with a high product recovery yield. The best result was obtained by starting diafiltration after concentrating the broth to 20% PMV. By doing so, a 98% product recovery yield was achieved in the shortest time while keeping the permeate volume at a minimum level.

• Membrane and Water Treatment
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• v.8 no.1
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• pp.1-18
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• 2017

In this study, reuse of biologically treated wastewater of denim washing and dyeing industry has been evaluated by membrane technologies. After that experiments were carried out at laboratory scale in textile dyeing unit by using obtained permeate water samples on 100% cotton based raw fabric belonging to examined industry. During membrane experiments, two different UF (UC100 and UC030) and two different NF (NP010 and NP030) were evaluated under alternative membrane pressures. In permeate water obtained on selected samples, conductivity at the range of $1860-2205{\mu}S/cm$, hardness at the range of 60 to 80 mg/L, total color at the range of 2.4 to 7.6 m-1 and COD at the range of 25-32 mg/L was determined. The following analyzes were performed for the dyed fabrics: perspiration fastness, rub fastness, wash fastness, color fastness to water, color fastness to artificial light, color measurement through the fabric. According to analysis results, selected permeate water have no negative impact on dyeing quality. The study showed that membrane filtration gave good performance for biologically treated textile wastewater, and NF treatment with UF pre-treatment was suitable option for reuse of the effluents.

• Korean Membrane Journal
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• v.7 no.1
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• pp.34-41
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• 2005

The wastewater discharged from a paper plant was filtrated by 3 kinds of tubular carbon ceramic UF and MF membranes with $N_2$-backflushing. The filtration time (FT) was fixed at 8 min or 16 min, and $N_2$-backflushing time (BT) was changed in 0${\~}$60 sec. The optimal condition was discussed in the viewpoints of total permeate volume ($V_T$), dimensionless permeate flux (J/Jo) and resistance of membrane fouling ($R_f$). In the viewpoints of $V_T$, J/Jo and $R_f$, the optimal $N_2$-BT was 40 sec at both FT for M9 (MWCO: 300,000 Daltons) and C005 ($0.05{\mu}m$) membranes. However, for C010 ($0.1{\mu}m$) it was 10 sec at FT=8 min, and 20 sec at FT=16 min in the viewpoints of J/Jo and $R_f$, and 5 sec at both FT in the viewpoints of $V_T$. It means that the short $N_2$-BT could reduce the membrane fouling and recover the permeate flux sufficiently for MF membrane having a large pore size as C010. Average rejection rates of pollutants were higher than $99.0\%$ for turbidity and $22.8{\~}59.6\%$ for $COD_{cr}$, but rejection rates of total dissolved solid (TDS) were lower than $8.9\%$. Therefore, the low turbidity water purified in our system could be reused for paper process.

• Journal of Environmental Science International
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• v.7 no.2
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• pp.209-216
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• 1998

Nanofiltration[NF45] and reverse osmosis membrane(HR98PP) separation treatment of dyestuff wastewater was carried out In order to separate relatively pure water from synthetic dyestuff wastewater, which consists of reactive dye, acid dye, basic dye, direct dye, and disperse dye. The experiments were performed by using the plate and frame membrane module. In the nanofiltration and reverse osmosis membrane separation, When the NaCl concentration was 0.1, 5.0, and 20.091, retention was 63.0, 46.0, 0.9%, respectively. When permeate flux was 125.0, 67.5, and 45.0 L/$m^2$ h, the osmotic pressure increased with Increasing the NaCl concentration. Permeate flux of two membranes Increased as temperature Increased due to segmental movement of polymer of the membrane and the rejection rate of dyestuff was decreased gradually. It was found that the rejection rate was about 95% in the nanofiltratlon, while the reverse osmosis membrane showed a high rejection rate of 99% under all temperature and pressures conditions.