• Membrane Journal
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• v.7 no.2
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• pp.84-94
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• 1997

The performances of both module sets made by different methods for helical module were compared. All experiments were conducted simultaneously at the same transmembrane pressure and energy cosumption per membrane area. The effects of Dean vortices for reducing concentration polarization and fouling were low for the first module set. The increase of 115% for permeate flux improvement(permeate flux difference ${\times}100$/pemeate flux of linear module) was measured. The second module set was more effective in reducing concentration polarization and fouling.

• Membrane Journal
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• v.8 no.1
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• pp.42-49
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• 1998

Effects of operating time, pH, temperature, concentration and addition of proteolytic enzyme on permeate flux for the ultrafiltration of gelatin and bovine serum albumin(BSA) solutions were studied. The results showed that permeate flux of gelatin solution was maintained almost constant during the operating time, and that of BSA solution was decreased to 66% of the initial value after 40 min operation. The permeate flux of gelatin solution was increased by increasing temperature. The permeate flux of BSA solution was constant in the temperature range of 30~$50{\circ}C$, but increased at $60{\circ}C.$. The permeate fluxes of gelatin and BSA solution showed minimum values near the isoelectric point of pH 5.0. The permeate fluxes of 1%(w/v) and 6% gelatin solution were $43.0l/m^2\cdot hr$ and $13.5l/m^2\cdot hr$, respectively. Those of 1% and 4% BSA solution were $33.0l/m^2\cdot hr$ and $14.0l/m^2\cdot hr$, respectively. The permeate fluxes of gelatin and BSA solutions were decreased to 68.6% and 57.6% of their initial values by increasing their concentration, respectively. The permeate fluxes of gelatin and BSA solutions were enhanced by 30% with the addition of proteolytic enzyme.

• Membrane Journal
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• v.18 no.2
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• pp.168-175
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• 2008

This study was carried out for the plate and frame membrane modules equipped with and without plastic protuberances on the support frame in order to determine the effect of eddy flow induced by the protuberances on permeate flux. The initial time for rapidly declined permeate flux on the module with protuberances was delayed twice or more than that on the module without protuberances when kaolin solution was permeated at the operating pressures from 0.4 to 1.6 bar. Also decreasing ratio of the kaolin solution to pure water flux for module with protuberances was 1 to 5% lower than that for module without protuberances. The flux improvement due to protuberances at laminar flow corresponding Reynolds number 1,750 was about double as compared with that in the transition flow region. In general, the kaolin fouling reduction for the plate module with protuberances during initial filtration process was very effective, even though the permeate flux after 60 minutes filtration did not increase significantly.

• Applied Science and Convergence Technology
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• v.23 no.5
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• pp.248-253
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• 2014

Air Gap Membrane Distillation (AGMD) is one of several technologies that can be used to solve problems fresh water availability. AGMD exhibits several advantages, including low conductive heat loss and higher thermal efficiency, due to the presence of an air gap between the membrane and condensation wall. A previous study by Bhardwaj found that the condensation surface properties (materials and contact angle) affected the total collected fresh water in the solar distillation process. However, the process condition differences between solar distillation and AGMD might result in different condensation phenomena. In contrast, N. Miljkovic showed that a hydrophobic surface has higher condensation heat transfer. Moreover, to the best of our knowledge, there is no study that investigates the effect of condensation surface properties in AGMD to overall process performance (i.e. flux and thermal efficiency). Thus, in this study, we treated the AGMD condensation surface to make it hydrophobic or hydrophilic. The condensation surface could be made hydrophilic by immersing and boiling plate in deionized (DI) water, which caused the formation of hydrophilic aluminum hydroxide (AlOOH) nanostructures. Afterwards, the treated plate was coated using hexamethyldisiloxane (HMDSO) through plasma-enhanced chemical vapor deposition (PECVD). The result indicated that condensation surface properties do not affect the permeate flux or thermal efficiency significantly. In general, the permeate flux and thermal efficiency for the treated plates were lower than those of the non-treated plate (pristine). However, at a 1 mm and 3 mm air gap, the treated plate outperformed the non-treated plate (pristine) in terms of permeate flux. Therefore, although surface wettability effect was not significant, it still provided a little influence.

• 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.

• 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.

• 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 Korean Society on Water Environment
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• v.18 no.2
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• pp.131-140
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• 2002

Laboratory-scale membrane bioreactor added alum into the anaerobic basin as a flocculant and adsorbent was carried out to find removal efficient of nitrogen and phosphorus components in the mixed liquid and weather or not maintaining the stability for the permeate flux and pressure at various internal recycle conditions. It was found that denitrification efficient of maximum 65% was obtained when the ratio of internal recycle was 3Q. Additionally when the ratio of internal recycle was fixed at 3Q, $BOD_5$ and T-P concentration of permeate was much more reduced compared to not added alum in anaerobic basin but T-N concentration of permeate was relatively increased. In case of added alum as the flocculant and adsorbent in anaerobic basin, the permeate flux was maintained above $10{\ell}/m^2/hr$ but the permeate pressure was relatively higher than alum was not added in anaerobic basin.

• Korean Journal of Food Science and Technology
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• v.30 no.2
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• pp.397-406
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• 1998

Hen egg white lysozyme (HEWL) is very valuable as a natural preservative in food processing due to its selective bactericidal activity. HEWL which traditionally isolated by crystallization or freeze drying was simply separated from 13 different hen egg white (HEW) proteins by a single-step ultrafiltration. Freeze dried HEW (0.25%, w/v) dissolved in a citrate-phosphate buffer (pH 4.6) was ultrafiltered with a PM30 membrane under various operating conditions, by changing concentration, temperature, transmembrane pressure $({\triangle}P_T)$, and stirring speed. Optimum separation conditions were decided when maximal flux was obtained. Under the optimum separation conditions, the effect of membrane material and fouling on flux as time passed as well as lysozyme concentration, protein concentration, specific activity (SA) in the permeate were measured. Best separation conditions of HEWL with PM30 membrane were sample concentration 0.25%, temperature $35^{\circ}C$, ${\Delta}P_T\;30\;psi$, and stirring speed 300 rpm. During the first 12 min, the flux of YM30 was higher, but at the steady-state it was lower than that of PM30. The SA of the PM30 permeate was over 2 times higher in spite of the lysozyme and protein concentration being lower than that of YM30 permeate. The flux of 5 times used PM30 decreased 30% compared to a new PM30, but both had the same tendency in flux decrease when time passed. Both of them reached a steady-state after 35 min and remained at 70% of the initial flux. In the PM30 permeate, the lysozyme concentration and SA were 110 units/mL and 2,821 units/mg protein, respectively. Therefore, PM30 membrane separation was very effective for separation of antimicrobial lysozyme.

• Membrane Journal
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• v.24 no.5
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• pp.400-408
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• 2014

This study is to evaluate the performance of draw solutions in forward osmosis desalination using fertilizer as draw solution. Considering osmotic pressure, solubility, and pH, $NH_4NO_3$, $NH_4H_2PO_4$, $(NH_4)_2HPO_4$, KCl, $KNO_3$, and $KHCO_3$ were screened from a comprehensive lists of fertilizer. Their performance were evaluated in terms of pure water permeate flux, reverse solute flux, and specific reverse solute flux for nitrogen and phosphorus. KCl showed the highest pure water permeate flux among the selected fertilizers while $(NH_4)_2HPO_4$ draw solution had the lowest flux. $NH_4H_2PO_4$ showed the lowest reverse solute flux and specific reverse solute flux for nitrogen followed by $(NH_4)_2HPO_4$, $KNO_3$, and $NH_4NO_3$. Although the pure water permeate flux of $NH_4H_2PO_4$ is lower than the other draw solutions, because it contains both nitrogen and phosphorus, and have the lowest reverse solute flux and specific reverse solute flux, it is a promising candidate as draw solution for forward osmosis desalination.