• 상하수도학회지
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• 제23권4호
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• pp.499-505
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• 2009

Many other countries have investigated the residual sludge treatment process to save the existing water resource and produce the high suspended solid concentration sludge. There are various methods for concentrating residual sludge, but the membrane system has received the most interest for its efficiency. The objective of this study was to evaluate the application of membrane filtration system for the residual sludge treatment. The experiment equipment was composed of Lab scale Crossflow tubular membrane filtration system. Generally, crossflow operation mode demands high electric cost mainly for the pump energy. So to cut off electric cost, very low Crossflow velocity was used in this experiment. Results confirmed that suspended solid concentration of residual sludge could be concentrated to 57,000mg/L in low Crossflow velocity tubular membrane system,. This concentration can be directly injected into the dehydrator. Based on the results, we know that the Crossflow tubular membrane system should be replaced conventional residual sludge treatment system.

• 한국입자에어로졸학회지
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• 제10권3호
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• pp.99-108
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• 2014

Liquid filtration by membrane filters is essential for the preparation of ultrapure water in semiconductor manufacturing processes. The separation of submicrometer particles suspended in ultrapure water with a laminated fibrous membrane filter was studied numerically and experimentally in the present work. We found that an electrical double layer around a single fiber expanded to a large extent at a low ion concentration, as in ultrapure water, and deformed toward the upstream of the fiber with increasing filtration velocity. Since an increase in the electrical double-layer thickness leads to a decrease in the electrical potential gradient, particles with the same polarity as the fiber approach the fiber more easily and are captured at a high filtration velocity. Experimental results also confirmed that the collection efficiency of polystyrene latex(PSL) particles through a PTFE filter became higher as the filtration velocity increased.

• Membrane and Water Treatment
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• 제9권5호
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• pp.343-351
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• 2018

As membrane fouling is based on various factors, it is a complex phenomenon that is hard to estimate. This study investigated membrane fouling in a thermophilic jet loop membrane bioreactor (JLMBR). With this purpose, four different empirical membrane fouling models with different sludge retention times were applied on the flow data obtained in the system. As a result of the model implementation, it was found for all sludge retention times that, standard blocking is effective in the first 1.5 hours of filtration, while cake filtration was dominant in the remaining duration. Additionally, it was observed that as the sludge retention time increases, membrane fouling rate decreases.

• 상하수도학회지
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• 제22권6호
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• pp.633-640
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• 2008

In this research, the $3.6m^3/day$ scale pilot plant consisting preozonation, coagulation, flocculation, and ceramic membrane processes was operated for long term period to evaluate the validity of ceramic membrane filtration process for treating lake water containing high concentration manganese. The higher concentration of dissolved manganese($Mn^{2+}$) was effectively oxidized to the bigger insoluble colloidal manganese ($MnO^2$) by 1~2 mg/L ozone. The colloidal manganese reacted with coagulant (poly aluminium chloride, PAC) and then formed the big floc. Ceramic membrane rejected effectively manganese floc during membrane filtration. Dissolved organic carbon(DOC) removal was dependent upon $Mn^{2+}$ concentration. While average $Mn^{2+}$ concentration was 0.43 and 0.85 mg/L in raw water, DOC removal rate in preozonation was 26.5 and 13.5%, respectively. The decrease rate of membrane permeability was faster without preozonation than with preozonation while membrane fouling decreased with NOM oxidation by ozone. In conclusion, raw water containing high concentration of manganese can be effectively treated in preozonation-coagulation-ceramic membrane filtration system.

• Environmental Engineering Research
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• 제24권1호
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• pp.17-23
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• 2019

This study monitored changes in the level of heterotrophic bacteria in the filtrate and investigated the effect of stagnant water on it, using a batch-operated, gravity-driven membrane system for household water treatment. The filtration test was carried out in the presence and absence of stagnant water in the filtrate line. The results showed that stagnant water accelerated the heterotrophic bacteria levels, measured by heterotrophic plate count, even though the heterotrophic plate count of the filtrate finally increased up to $10^5CFU/mL$ regardless of the presence of stagnant water. When the change in heterotrophic plate count of a batch was monitored over filtration time, heterotrophic plate count of the filtrate rapidly decreased within 5 min for each batch filtration. Biofilm formation on the filtrate line was observed in the presence of stagnant water. The biofilm fully covered the filtrate line and contained numerous microorganisms. During storage after filtration, heterotrophic plate count increased exponentially. To improve the filtrate quality of a filtration-based household water treatment system, therefore, the stagnant water in the filtrate line should be minimized, the filtrate produced at the first 5 min is recommended not to be used as potable water, and the storage of filtrate should be avoided.

• 한국식품저장유통학회지
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• 제10권4호
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• pp.482-487
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• 2003

제주 지역의 대표적인 좁쌀 약주 제품에 대하여 유통 과정 중에 발생하는 침전 형성을 방지하기 위하여 여과 공정에 관한 연구를 실시하고 개선 방안을 제시하였다. 여러 공극 크기의 유리 막 여과지와 중공 사막 카트리지여과 매질을 가지고 좁쌀 약주를 여과한 결과, 대부분이 침전 형성 가능한 입자들은 1.2$\mu\textrm{m}$ 공극 크기의 여과 매질에 의한 여과로 제거 되는 것으로 조사되었다. 0.45$\mu\textrm{m}$ 중공 사막 카트리지인 경우 여과 flux는 342.8 lmh로 계산되었다. 여과에 따른 성분 변화는 크지 않은 것으로 조사되었다 그리고 4$^{\circ}C$와 실온을 48시간 씩 반복하면서 3개월간 저장 중 0.7$\mu\textrm{m}$ 공극 크기의 유리 막 여과지에 의한 여과에서도 미세한 침전 형성이 관찰되었다. 그러나 중공 사막인 경우에는 0.45$\mu\textrm{m}$에서도 침전 형성이 관찰되지 않았다. 따라서 완벽한 침전 형성 방지를 위해서는 현재 최종 여과 공정인 1 $\mu\textrm{m}$ 정밀 원통 여과지 공정 다음에 0.45$\mu\textrm{m}$ 중공 사막 여과 시스템도입이 효과적이다.

• 상하수도학회지
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• 제18권6호
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• pp.770-777
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• 2004

Three pilot-scale membrane systems were operated using lake water as influent in this study. Microfiltration (MF) membrane with pore size of 0.01 m was used in Systen I of which filtration mode was set at constant pressure of $1kgf/cm^2$. Ultrafiltration (UF) membranes with molecular cutoff (MWCO) of 80,000 and 13,000 were used in System II-1 and II-2, respectively. Constant flow mode was applied at the range between 0.7 and $1.5m^3/m^2{\cdot}d$ (average of $1.1m^3/m^2${\cdot}d) for System II-1 and between 0.37 and $1.65m^3/m^2{\cdot}d$ (average of $1.18m^3/m^2{\cdot}d$) for System II-2. In System I, the flux changed from $1m^3/m^2{\cdot}d$ to $0.2m^3/m^2{\cdot}d$ during the operation time of 5 months. System II showed recovery of 94% under the allowable maximum pressure of $3kgf/cm^2$ during the same operation period. From these results, the efficient operation was observed in constant flow mode with respect to filtration time and recovery. Average filtrate turbidity showed 0.0071 NTU in System I and 0.0054 NTU in System II, which implied that high turbidity removal was obtained in both MF and UF systems with no significant difference between MF and UF. From the fact that membrane flux depends largely on membrane type and operation mode, a guideline of optimum design and operation should be suggested for application of membrane systems to full scale water treatment.

• Membrane and Water Treatment
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• 제5권2호
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• pp.73-86
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• 2014

Membrane fouling is a major challenge limiting the use of membrane applications. In this study high induced shear rates were utilized at the membrane surface in order to reduce the organic and inorganic scaling by using the torsional vibration of flat sheet membranes. The performances of a vibratory shear-enhanced processing (VSEP) system for the ultrafiltration (UF), nanofiltration (NF) and reverse osmosis (RO) membrane filtration of industrial dairy wastewater were investigated. The vibration and non-vibration methods were compared with the same membrane and operational parameters during the purification of real dairy industrial process wastewater. In the initial experiments, short-term tests were carried out in which the effects of vibration amplitude, recirculation flow rate and transmembrane pressure were measured and compared. The permeate flux, turbidity, conductivity and chemical oxygen demand (COD) reduction of dairy wastewater were investigated by using UF, NF and RO membranes with vibration and non-vibration methods. In the subsequent experiments, concentration tests were also carried out. Finally, scanning electron microscopy (SEM) revealed that the vibration method gave a better performance, which can be attributed to the higher membrane shear rate, which reduces the concentration of solids at the membrane, and the transmission.

• Membrane and Water Treatment
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• 제12권1호
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• pp.23-35
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• 2021

A POM-membrane was fabricated by immobilizing a keggin type polyoxometalate (POM) H5PV2Mo10O40 onto the surface of microporous flat-sheet polymeric polyvinylidene fluoride (PVFD) membrane using a chemical deposition method. The POM-membrane was characterized by FT-IR, SEM and EDX to confirm existing of the POM onto the membrane surface. The POM-membrane was used to remove an anionic textile dye (Reactive Black 5 named as an RB5) from aqueous phases with a cross-flow membrane filtration and a batch adsorption system. The dye removal efficiency of the POM-membrane using the cross-flow membrane filtration system and the batch adsorption system was about 88% and 98%, respectively. The influence factors such as contact time, adsorbent dosage, pH, and initial dye concentration were investigated to understand the adsorption mechanism of the RB5 dye onto the POM-membrane. To find the best fitting isotherm model, Langmuir, Freundlich, BET and Harkins-Jura isotherm models were used to analyze the experimental data. The isotherm analysis showed that the Langmuir isotherm model was found to the best fit for the adsorption data (R2 = 0.9982, qmax = 24.87 mg/g). Also, adsorption kinetic models showed the pseudo second order kinetic model was found the best model to fit the experimental data (R2 = 0.9989, q = 8.29 mg/g, C0 = 15 ppm). Moreover, after four times regeneration with HNO3 acid, the POM-membrane showed high regenerability without losing dye adsorption capacity.

• 한국막학회:학술대회논문집
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• 한국막학회 2001년도 국제 Workshop:상수원의 현황과 분리막 상수처리(Water Resource and Menbrane Water Treatment)
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• pp.155-162
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• 2001

Advanced drinking water production systems, which not only good quality product water, but also provide easy management and mainenance of facilities, and operate on a smaller site area, have been expected to be developed for some time. We are going ahead with a program to deveop an advanced drinking water production system, using immersed membrane filtration combined with biological activated carbon, to meet the need described above. The demonstration plant tests been conducted with surface water from the Yodo-river since Dec. 1998 to measure treatment performance, reliability, and controllability of the system. The quality of product water has consistently remained at a very high level for about 2 years under controlled conditions. Results showed that the re-circulation granular biological activated carbon could suppress the increase of membrane pressure difference and promote a reduction of dissolved organic matter. (This work has been conducted along the ACT21 Programs.)