• Membrane and Water Treatment
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• 제3권3호
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• pp.141-149
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• 2012

The aeration provided in a Submerged Membrane Bioreactor (SMBR) improves membrane filtration by creating turbulence on the membrane surface and reducing membrane resistance. However, conventional hollow fiber membrane modules are generally packed in a vertical orientation which limits membrane scouring efficiency, especially when aeration is provided in the axial direction. In the present research, 3 innovative hollow-fiber membrane modules, each with a different membrane orientation, were developed to improve membrane scouring efficiency and enhance permeate flux. Pilot testing was performed to investigate the permeate flux versus time relationship over a 7-day period under different intermittent modes. The results indicated that the best module experienced an overall permeate flux decline of 3.3% after 7 days; the other two modules declined by 13.3% and 18.3%. The lower percentage of permeate flux decline indicated that permeate productivity could be sustained for a longer period of time. As a result, the operational costs associated with membrane cleaning and membrane replacement could be reduced over the lifespan of the module.

• Membrane and Water Treatment
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• 제9권1호
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• pp.53-62
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• 2018

In this study, vacuum membrane distillation (VMD) was used to treat high-salinity wastewater (concentration about 17%) discharged by chlor-alkali plant after resin regeneration. The feasibility of VMD for the treatment of real saline wastewater by using Polyvinylidene fluoride (PVDF) microporous plate membrane with a pore diameter of $0.2{\mu}m$ was investigated. The effects of critical operating parameters such as feed temperature, velocity, vacuum degree and concentration on the permeate water flux were analyzed. Numerical simulation was used to predict the flux and the obtained results were in good agreement with the experimental data. The results showed that an increase in the operating conditions could greatly promote the permeate water flux which in turn decreased with an increase in the concentration. When the concentration varied from 17 to 25%, the permeate water flux dropped marginally with time indicating that the concentration was not sensitive to the decrease in permeate water flux. The permeate water flux decreased sharply until zero due to the membrane fouling resistance as the concentration varied from 25 to 26%. However, the conductivity of the produced water was well maintained and the average value was measured to be $4.98{\mu}s/cm$. Furthermore, a salt rejection of more than 99.99% was achieved. Overall, the outcome of this investigation clearly indicates that VMD has the potential for treating high-salinity wastewater.

• Membrane and Water Treatment
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• 제12권2호
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• pp.65-73
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• 2021

Sponge ball cleaning can generate an abrasion effect, which leads to an attractive increasing in both permeate flux and membrane rejection. The aim of this study was to investigate the influence of the daily sponge ball cleaning (SBC) on the performance of different UF cross-flow membrane modules integrated with a bioreactor. Two 1"-membrane modules and one 1/2"-membrane module were tested. The parameters measured and controlled are temperature, pH, viscosity, particle size, dissolved organic carbon (DOC), total suspended solids (TSS), and permeate flux. The permeate flux could be improved by 60%, for some modules, after 11 days of daily sponge ball cleaning at a transmembrane pressure of 350 kPa and a flow velocity of 4 m/s. Rejection values of all tested modules were improved by 10%. The highest permeate flux of 195 L/㎡.h was achieved using a 1"-membrane module with the aid of its negatively charged membrane material and the daily sponge ball cleaning. In addition, the enhancement in the permeate flux caused by daily sponge ball cleaning improved the energy specific demand for all tested modules. The negatively charged membrane showed the lowest energy specific demand of 1.31 kWh/㎥ in combination with the highest flux, which is a very competitive result.

• Membrane and Water Treatment
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• 제10권5호
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• pp.321-330
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• 2019

The objective of this study was to examine the recovery of the power plant cooling tower blowdown water (CTBD) by membrane distillation. The experiments were carried out using a flat plate poly vinylidene fluoride (PVDF) membrane with a pore diameter of $0.22{\mu}m$ by a direct contact membrane distillation unit (DCMD). The effects of operating parameters such as transmembrane temperature difference (${\Delta}T$), circulation rate and operating time on permeate flux and membrane fouling have been investigated. The results indicated that permeate flux increased with increasing ${\Delta}T$ and circulation rate. Whereas maximum permeate flux was determined as $47.4L/m^2{\cdot}h$ at ${\Delta}T$ of $50^{\circ}C$ for all short term experiments, minimum permeate flux was determined as $7.7L/m^2{\cdot}h$ at ${\Delta}T$ of $20^{\circ}C$. While $40^{\circ}C$ was determined as the optimum ${\Delta}T$ in long term experiments. Inorganic and non-volatile substances caused fouling in the membranes.

• 한국식품과학회지
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• 제24권3호
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• pp.199-203
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• 1992

한외여과를 이용하여 다시마 열수추출물로 부터 가용성 저분자량의 정미성분을 회수하는데 필요한 조건을 최적화하기 위해, 분리막 선정 및 온도, 압력, Flow rate의 영향을 고찰하였고 선정된 최적 조건하에서 한외여과와 Diafiltration을 실시하여 투과유량의 flux profile과 정미성분의 회수율을 비교하였다. 분리막은 소수성인 GR 51PP가 친수성인 FS 형태보다 높은 투과유량을 유지하였다. Flow rate의 증가에 따라서 투과유량도 증가하는 경향을 보였으나 3.7 l/min에서 한계값을 나타내었다. 한편, 압력이 높은 경우에는 Steady-state에서 투과유량이 감소하는 경향을 보였고 온도 증가에 따라서는 큰 변화는 없었다. 한외여과와 Diafiltration 실시에 따른 투과유량의 Flux profile과 전체 고형분과 정미성분의 회수율을 조사한 결과 한외여과를 실시한 경우가 비교적 높은 회수율을 보였으나 투과유량은 전반적으로 Diafiltration 보다 낮았다.

• 멤브레인
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• 제18권4호
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• pp.354-361
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• 2008

자연유기물을 처리하는 혼합 오존-세라믹 한외여과 수처리 시스템에서 막의 운전조건과 처리수의 화학적 조성이 세라믹 막의 투과플럭스에 미치는 영향을 연구하였다. 오존주입량, 막간압력 그리고 교차흐름속도를 포함한 운전조건의 영향을 관찰한 결과, 막의 투과플럭스는 오존주입량과 교차흐름속도가 증가할수록 그리고 막간압력이 감소할수록 증가하였다. 오존주입으로 인한 막오염의 감소는 교차여과에서 오존기체방울에 의해 발생하는 오염물질의 물리적인 역수송보다는 촉매 금속산화물로 이루어진 세라믹막 표면에서 발생하는 오존과 자연유기물간의 화학반응에 의한 영향에 더욱 의존할 수 있음을 확인하였다. 그러나 이와 같은 막오염의 감소는 상대적으로 높은 막간압력을 적용 시 줄어드는 경향을 나타내었다. 모델 자연유기물을 이용하여 실험한 결과, 높은 pH에서는 칼슘의 첨가로 인해 투과플럭스가 급격하게 감소하였으나 상대적으로 낮은 pH에서는 투과플럭스 감소에 대한 칼슘의 효과는 저하되었다. 혼합 오존-세라믹만 시스템에서 연속적인 오존주입은 세라믹막 표면에서 발생하는 촉매오존산화에 의한 자연유기물의 분해로 운전 초기 막의 투과플럭스의 감소 후 궁극적으로는 막의 투과플럭스를 회복시킬 수 있음을 확인할 수 있었다.

• 한국환경과학회지
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• 제7권1호
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• pp.74-80
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• 1998

Because permeate flux was very low as It has the suspension soled of higher concentration In the trafiltration membrane separation treatment of dyestuff wastewater, pre-treatment of Ponton reaction was carried out. In the case of pH 3, COD removal rate was the hi각erst of 58%. When PAC was added into the pre-treatment supernatant, the COD removal rate was found to be 53% , and when COD was 153mg/L, the removal rate was 92.3% in the trafiltration separation. In addition, the effect of the addition of PAC on the permeate flux was also investigated. The decrease of permeate flux In the presence of PAC was higher than In the abscence of PAC, but the recovery of permeability by cleaning was better In the case of PAC system.

• 한국환경과학회지
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• 제9권2호
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• pp.173-176
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• 2000

This study was carried out to investigate the filtration characteristics of membrane modules according to hollow fiber dispersion for direct solid-liquid separation of activated sludge. 2 bundle, 4 bundle, and 10 bundle, and 10 bundle module used in this experiment according to hollow fiber dispersion was manufactured at laboratory and permeate flux and transmembrane pressure(TMP) of each module were observed under a suction pressure of 0.5kgf/c$m^2$. As the hollow fibers were dispersed, permeate flux was increased and TMP was decreased. Permeate flux and TMP of each module was 15.0 $\ell$/$m^2$.h and 31.8 cmHg for 2 bundle, 16.0 $\ell$/$m^2$ .h and 17.4 cmHg for 4 bundle, and 20.4 $\ell$/m2 .h and 31.8 cmHg for 10 bundle. In conclusion, the membrane fouling is expected to be decrease by maintaining lower TMP with hollow fiber dispersion.

• 멤브레인
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• 제19권3호
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• pp.194-202
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• 2009

본 연구에서 처리수를 이용한 주기적인 역세척은 춘천시 공지천의 관형 세라믹 한외여과막에 의한 고도정수처리 시스템에서 막오염을 저감하고 투과선속을 향상시키고자 수행되었다. 일정한 역세척 시간(BT) 15초에서 여과시간 즉, 물 역세척 주기(FT) 2분이 가장 높은 무차원 투과선속(초기 투과선속에 대한 투과선속)과 가장 낮은 막오염 저항값을 보였다. 또한, FT 10분으로 고정한 BT 영향의 결과에서 BT 20초가 가장 낮은 막오염 저항과 가장 높은 무차원 투과선속을 나타내어, 가장 많은 총여과부피 107.3 L를 얻을 수 있었다. 결론적으로 공지천의 정수처리에서 FT 10분과 BT 20초가 최적조건으로 관형 알루미나 정밀여과의 선행 연구결과와 정확히 일치하였다. 한편 관형 세라믹 한외여과 시스템에 의한 오염물질 평균제거율은 탁도 97.0%, 망간법에 의한 COD 32.1%, 암모니아성 질소 28.8%, 총인 54.4%로 나타났다.

• 멤브레인
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• 제8권2호
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• pp.94-101
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• 1998

폴리아크릴로니트릴 공중합계의 재질인 한외여과 중공사막 (분획분자량: $5\times 10^4$ Dalton)을 이용하여 금속표면처리 세척수로부터 오일입자를 제거하였다. 오일입자를 분리하고자 할 때 막표면에서의 농도분극 현상으로 투과플럭스를 감소시키므로 농도분극을 억제하기 위하여 질소기체로 역세척을 수행하였다. 정상운전 및 역세척시간을 각기 달리하여 운전함으로써 얻어진 투과플럭스의 거동을 정량적으로 비교하였다. 실험결과, 실질투과플럭스 증가율의 산출을 기준으로 정상운전시간/역세척시간이 10분/40초인 조건이 역세척을 하지 않은 경우와 비교하여 가장 높은 증가율 (약 23%)을 보였다. 하지만, 실제 운전에서 중요하게 고려되는 시간에 따른 투과플럭스의 안정성은 정상운전시간이 연장되면 크게 떨어짐을 알 수 있었다. 막투과플럭스가 역세척압력에 무관하게 일정한 거동을 보이는 레이놀즈수 이상에서는 역세척압력이 증가할수록 투과플럭스는 n제곱승으로 증가하는 상관관계를 보였고, 원료공급속도가 증가할수록 투과플럭스의 증가정도는 상승하는 경향을 나타냈다.