• Journal of Biomedical Engineering Research
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• v.26 no.5
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• pp.337-341
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• 2005

Blood pulsation has been reported to have an advantageous effect on extracorporeal blood circulation. However, the study of pulsatile blood flow in renal replacement therapy is very limited. The in-vitro experimental results of pulsatile blood flow on ultrafiltration, when compared with the conventional roller pump, are described in this paper. Methods: Blood flow rate (QB) and transmembrane pressure (TMP) were considered as regulating factors that have an influence on ultrafiltration. Experiments were performed under the condition of equal TMP and OB in both pulsatile and roller pump groups, Several kinds of hollow fiber dialyzers were tested using distilled water containing chemicals as a blood substitute. Mean TMP (mTMP) varied from 10 to 90mmHg while the QB was 200ml/min. Results: Ultrafiltration rate (QUF) was found to be linearly proportional to TMP, whereas QB had little influence on QUF. In addition, QUF was higher in the pulsatile group than the roller pump group at the identical TMP. Conclusion: In the controlled test, QUF increased solely as a consequence of blood pulsation, which implies that the pulse frequency represents an additional and important clinical variable during renal replacement therapy.

• Membrane Journal
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• v.28 no.1
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• pp.62-66
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• 2018

In this study the cleaning spherical beads with same density as water were fabricated. Bead moving velocity was measured with respect to the aeration rate and bead concentration in water reservoir. The permeation experiments for FR (filtration and relaxation) and SFCO (sinusoidal filtration continuous operation) modes were simultaneously carried out under the condition of 1 to 3% cleaning spherical bead concentration, 20 LMH and 500 mL/min aeration rate in the MLSS 8,000 mg/L activated sludge solution. The used membrane was the $90cm^2$ effective area and $0.4{\mu}m$ nominal pore size flat membrane. The TMP (transmembrane pressure) decreased as the bead concentration increased, and was shown most effective in FR mode with 2% bead concentration.

• Environmental Engineering Research
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• v.23 no.2
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• pp.159-163
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• 2018

The feasibility of applying coagulation-integrated microfiltration (MF) as a pretreatment for an ultrafiltration (UF) feed in oily wastewater treatment was investigated. The effects of different coagulants on oil removal rates from wastewater were studied. The maximum oil removal rate of 82% was obtained after coagulation with 130 mg/L of polyaluminium chloride (PAC). UF flux reached $95L/(m^2{\cdot}h)$ with coagulation-integrated MF as pretreatment. This value was 2.5 times higher than that flux obtained without pretreatment. The value of UF flux increased as the transmembrane pressure (TMP) and cross-flow velocity (CFV) of the UF module increased. UF flux gradually increased when TMP and CFV exceeded 0.4 MPa and 3 m/s, respectively, because of concentration polarization and membrane fouling stabilization. Chemical oxygen demand reduction and oil removal rate reached 95.2% and 98.5%, respectively, during integrated membrane processing with a PAC concentration of 130 mg/L, TMP of 0.4 MPa, and CFV of 3 m/s for UF. In addition, sequentially cleaning the fouling membrane with NaOH and $HNO_3$ aqueous solutions caused UF flux to recover to 90%. These encouraging results suggested that the hybrid integrated membrane process-based coagulation and MF + UF are effective approaches for oily wastewater treatment.

• Membrane Journal
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• v.26 no.6
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• pp.470-479
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• 2016

In the advanced treatment of sewage using the submerged membrane-coupled sequencing batch reactor (SMSBR) with media, the effect of media on the filtration performance and removal efficiency were investigated. Dosages of the media in the SMSBR were 10% based on working volume of reactor. As a control system, SMSBR without media and PAC, SMSBR with PAC (10 g/L) only, and SMSBR with media and PAC were also operated. The experimental results showed that there was no big difference observed in the removal efficiencies of COD, T-N, and T-P irrespective of the dosages of the media and PAC. But transmembrane pressure (TMP) of SMSBR with media increased slowly during the operation time, while that of SMSBR without media increased rapidly. Using SMSBR with media, it was possible to operate without the membrane cleaning during the 91 days. Using SMSBR with media only, after 80 days the average removal efficiencies of COD, T-N, and T-P were 95.0, 69.3%, and 51.4%, respectively.

• Membrane Journal
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• v.17 no.2
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• pp.124-133
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• 2007

In this study, we treated lake water by 2 kinds of multichannel ceramic micro filtration membranes. We could investigate effects of $N_2-back-flushing$ time (BT) and transmembrane pressure (TMP), and find optimal operating conditions. The BT were changed in $10{\sim}60$ sec, TMP in $0.6{\sim}2.0$ bar at fixed filtration time (FT) 8 min, flow rate 2.0 L/min and back-flushing pressure 2.0 bar. Also, the optimal conditions were discussed in the viewpoints of resistance of membrane fouling $(R_f)$, dimensionless permeate flux $(J/J_o)$, permeate flux (J) and total permeate volume $(V_T)$. As result, optimal back-flushing conditions for HC04 ($0.4{\mu}m$ pore size) and HC10 membrane $(1.0{\mu}m)$ were BT=10 sec and BT=20 sec, respectively. Then, higher TMP should increase the driving force, and could produce more VT. Average rejection rates of pollutants were higher than 95.4% for turbidity, $12.7{\sim}20.1%\;for\;COD_{Mn},\;0.0{\sim}6.4%\;for\;NH_3-N,\;1.9{\sim}4.6%$ for T-N and $34.9{\sim}88.4%$ for T-P.

• Membrane and Water Treatment
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• v.3 no.2
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• pp.77-98
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• 2012

A two-dimensional (2D) steady state numerical model of concentration polarisation (CP) phenomena in a membrane channel has been developed using the commercially available computational fluid dynamics (CFD) package CFX (Ansys, Inc., USA). The model incorporates the transmembrane pressure (TMP), axially variable permeate flux, variable diffusivity and viscosity, and osmotic pressure effects. The model has been verified against several benchmark analytical and empirical solutions from the membrane literature. Additionally, the model is able to predict the rejection of an arbitrary solute by the membrane using a pore model, given some basic knowledge of the geometry of the solute molecule or particle, and the membrane pore geometry. This allows for predictive design of membrane systems without experimental determination of the membrane rejection for the specified operating conditions. A demonstration of the model is presented against experimental results for two uncharged test compounds (sucrose and PEG1000) from the literature. The model will be extended to incorporate charge effects, transient simulations, three-dimensional (3D) geometry and turbulent effects in future work.

• Journal of Korean Society of Water and Wastewater
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• v.32 no.2
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• pp.97-106
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• 2018

In this study, the effect of chemically enhanced backwash(CEB) coping with algal(Heterosigma Akashiwo) inflow was evaluated in the seawater desalination pretreatment process using ceramic membrane. In order to confirm the possibility of long-term filtration operation, the recovery rate of transmembrane pressure(TMP) due to the CEB using NaOCl was examined. When the membrane flow rate was 83.3 LMH, the TMP was maintained within 200 kPa for 84 hours in seawater influent. As the algal counts of 30,000 cell/mL were injected into the influent of seawater, however, the TMP rapidly increased and exceed maximum value. Membrane fouling caused by the algae was very poorly recovered by usual physical backwash. The CEB was performed for 30 min(3 min circulation / 27 min immersion) with 300 mg/L of NaOCl. As a result of the CEB application, it was possible to maintain a stable operating of filtration during 10 days and the average recovery rate of TMP by the CEB was 98.1%. It has been confirmed that the CEB using NaOCl is very effective in removal of membrane fouling by algae, resulted in stable membrane filtration for the long-term operation.

• Membrane Journal
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• v.25 no.6
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• pp.524-529
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• 2015

In this study transmembrane pressure (TMP) was measured with respect to operational time by applying the sinusoidal flux continuous operation (SFCO) for the hollow fiber membrane. The hollow fiber module which has $100cm^2$ of effective area and $0.45{\mu}m$ nominal pore size was submerged in the activated sludge solution of MLSS 5,000 mg/L. The critical permeate flux was measured as $26.6L/m^2{\cdot}hr$ by the method of continuous flux step change. TMPs of the filtration/relaxation (FR), FR with backwashing (FR/BW) and SFCO modes were measured. The SFCO mode was more effective than FR and FR/BW modes below the critical permeate flux such as 15, 20 and $25L/m^2{\cdot}hr$. However, the FR/BW was confirmed as more effectively fouling controlled mode than SFCO mode above the critical permeate flux.

• Membrane Journal
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• v.11 no.4
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• pp.190-203
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• 2001

In this study the discharged wastewater from a paper plant was filtrated by 4 kinds of tubular carbon ceramic ultrafiltration membranes with periodic water-back-flushing. We could investigate effects of watch-back-flushing period, transmembrane pressure (TMP) and flow rate, and find optimal operating conditions. The back-f1ushing time (BT) was fixed at 3 sec, and fi1tration times (FT) werc changed in 15~60 scc, TMP in 1.00~2.50$kg_{f}$/$cm^2$, and the flow rates in 0.27~1.75 L/min. The optimal conditions were discussed in 7he viewpoints of dimensionless permeate flux (J/J$_{0}$), total permeate volume ($V^T$) and resistance of membrane fouling ($R^f$). Optima1 back-flushing period was BT/FT=0.20, suggesting that the frequent back-flushing should decrease membrane fouling. Optimal TMP in the viewpoint of $V^T$ was 1.00~1.55$kg_{f}$/$cm^2$, suggesting that rising TMP should increase membrane fouling and decrease permeate flux. But, rising f1ow rate should decrease membrane fouling and increase permeate flux. Then, average rejection rates of pollutants filtratedby carbon ceramic membranes were 88~98 % for turbidity, 48~72% fort $COD_{cr}$ and 37~76% for TDS.

• Journal of Korean Society of Water and Wastewater
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• v.33 no.6
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• pp.437-446
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• 2019

Reverse osmosis seawater desalination facilities can extend the cleaning cycle and replacement time of the reverse osmosis membrane by pretreatment process. Selection of pretreatment process depends on water quality. It was attempted in this study to select approriate pretreatment process for the Masan bay, which was high in particles and organic content. For this purpose, performances of pretreatment processes such as filter adsorber (FA), pore controllable fiber (PCF), and ultrafiltration (UF) were compared based on the silt density index (SDI). The SDI value of the filtrate should be less than 3. The study results showed that UF can produce the filtrate quality satisfying the requirement. However, the transmembrane pressure (TMP) of UF increased quickly, reaching 0.6 bar within 4 days. In order to secure stable operation, FA and PCF were combined with UF. The study results showed that combination of PCF and UF was able to extend the filtration duration (more than 2 months) until to reach TMP of 0.6 bar.