• Membrane and Water Treatment
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• 제7권4호
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• pp.355-365
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• 2016

The improvement of fouling resistance of porous polymeric membrane is one of the most important targets in membrane preparation for water purification in many process like wastewater treatment. Membranes can be modified by various techniques, including the treatment of polymer material, blending of hydrophilic polymer into polymer solution, and post treatment of fabricated membrane. This research proposed the modifications of morphology and surface property of hydrophobic membrane by blending polyethersulfone (PES) with three polymeric additives, polyvinylpyrrolidone (PVP), Pluronic F127 (Plu), and Tetronic 1307 (Tet). PES hollow fiber membranes were fabricated via dry-wet spinning process by using a spinneret with inner and outer diameter of 0.7 and 1.0 mm, respectively. The morphology changes of PES blend membrane by those additives, as well as the change of performance in ultrafiltration module were comparatively observed. The surface structure of membranes was characterized by atomic force microscopy and Fourier transform infra red spectroscopy. The cross section morphology of PES blend hollow fiber membranes was investigated by scanning electron microscopy. The results showed that all polymeric additives blended in this system affected to improve the performances of PES membrane. The ultra-filtration experiment confirmed that PES-PVP membrane showed the best performance among the three membranes on the basis of filtration stability.

• Membrane and Water Treatment
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• 제2권1호
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• pp.1-24
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• 2011

The deficiency of clean water is a major global concern because all the living creatures rely on the drinkable water for survival. On top of this, abundant of clean water supply is also necessary for household, metropolitan inhabitants, industry, and agriculture. Among many purification processes, advances in low-energy membrane separation technology appear to be the most effective solution for water crisis because membranes have been widely recognized as one of the most direct and feasible approaches for clean water production. The aim of this article is to give an overview of (1) two new emerging membrane technologies for water reuse and desalination by forward osmosis (FO) and membrane distillation (MD), and (2) the molecular engineering and development of highly permeable hollow fiber membranes, with polyvinylidene fluoride (PVDF) and polybenzimidazole (PBI) as the main focuses for the aforementioned applications in National University of Singapore (NUS). This article presents the main results of membrane module design, separation performance, membrane characteristics, chemical modification and spinning conditions to produce novel hollow fiber membranes for FO and MD applications. As two potential solutions, MD and FO may be synergistically combined to form a hybrid system as a sustainable alternative technology for fresh water production.

• Membrane and Water Treatment
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• 제2권2호
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• pp.105-119
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• 2011

This study presents the tests of an Immersed Membrane BioReactor (IMBR) equipped with a draft tube and focuses on the influence of hydrodynamic conditions on membrane fouling in a pilot-scale using a hollow fiber membrane module of ZW-10 under ambient conditions. In this system, the cross-flow velocities across the membrane surface were induced by a cylindrical draft-tube. The relationship between cross-flow velocity and aeration strength and the influence of the cross-flow on fouling rate (under various hydrodynamic conditions) were investigated using Multi-Dimension Scaling (MDS) analysis. MDS technique is especially suitable for samples with many variables and has relatively few observations, as the data about Membrane Bio-Reactor (MBR) often is. Observations and variables are analyzed simultaneously. According to the results, a specialized form of MDS, CoPlot enables presentation of the results in a two dimensional space and when plotting variables ratio (output/input) rather than original data the efficient units can be visualized clearly. The results indicate that: (i) aeration plays an important role in IMBR performance; (ii) implementing the MDS approach with reference to the variables ratio is consequently useful to characterize performance changes for data classification.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2007년도 춘계학술대회
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• pp.557-560
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• 2007

The durability of 80 kW class stack module was tested in hydrogen recirculation and non-recirculation systems with the condition of 300Amps (constant current mode) and hydrogen pulse purging (10 seconds close/0.8 seconds open). A localized membrane failure in the interfacial area between membrane and sub-gasket, carbon corrosion in cathode electrode, and Pt dissolution/extraction have been found through the post mortem analysis such as CV, Impedance, SEM, and so on. The main reason of these mechanisms will be discussed in this study.

• Biotechnology and Bioprocess Engineering:BBE
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• 제2권2호
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• pp.136-140
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• 1997

Direct membrane separation using nonwoven fabric was applied to saline wastewater treatment by an activated sludge process. A nonwoven fabric module was immersed in an aeration tank. The part of treated was filtered through the module by suction and the rest of that was separated by a settling tank. Various F/M ratios and salt concentrations were applied to investigate stable flux as well as pollutant removal. The pollutant removal efficiencies of nonwoven fabric separation was not affected by F/M ratios and salt concentrations and was higher than that of settling tank separation. The decline in flux was seemed to be caused by the biofilm on nonwoven fabric surface.

• KSBB Journal
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• 제15권5호
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• pp.529-536
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• 2000

Results from experiments and mathematical modeling were compared for pervaporative butanol fermentation. The developed model includes expressions to predict characteristics of butanol fermentation, such as, microbial growth, solvent (butanol, acetone, and ethanol) formation and organic acid (acetate and butyrate) production. Butanol diffusivity was 1.15${\times}$10(sup)-7 ㎡/hr at 1.5 L/min-tubing of air flow rate using a pervaporative module. The model correlated well with experimental results (cell growth, glucose consumption and concentrations of solvents and organic acids) for batch fermentation with and without pervaporation. Larger surface area and thinner module tubing resulted in an increased glucose consumption and a decreased residual butanol concentration. Optimum membrane area and thickness were 0.34 ㎡ and 120 $\mu\textrm{m}$, respectively.

• 멤브레인
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• 제11권4호
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• pp.152-160
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• 2001

본 연구는 아크릴 폐수의 COD제거를 위한 전터리 공정 및 전 처리된 아르릴폐수를 한외여과 중공사형 모듈과 역삼투 나권형 모듈에 적용하여 적용압력과 온토변화에 따른 한외여과막과 역삼투막의 분리특성을 고찰하였다. 또한, 장시간 연속운전으로부터 한외여과 및 역삼투 막의 세척 적정시간을 결정하고, 운전시간에 따른 막오염을 고찰하였다. 14시간을 기준으로 한외여과 막의 플럭스가 급격히 떨어지고 있으며, 역삼투 막도 비슷한 경향을 나타내고 있다. CaO 및 모래여과장치를 거친 처리수를 중화처리 하여 UF/RO공정에 적용한 결과 COD 및 TDS가 배출허용 기준치 이하로 제거됨을 알 수 있었다.

• 드라이브 ㆍ 컨트롤
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• 제16권2호
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• pp.51-58
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• 2019

In this study, flow analysis and dehumidification experiment were conducted on hollow fiber membrane module to determine the dehumidification characteristics of its various configurations. A quantitative analysis of the CFD for four different models with a temperature of $30^{\circ}C$ and 30%RH inlet humidity was conducted. Each model has different shape parameters i.e. the number of hollow fiber membranes and the presence or absence of baffles. After comparison between the flow analysis results and dehumidification experiment results, the percentage error was found to be approximately 2%. The moisture removal rate for each model was calculated using flow analysis data. It was found that the moisture removal rate of refined model with three baffles and eight hollow fiber membranes was highest among the four modeled modules of hollow fiber membrane one, i.e. about 60%.

• 멤브레인
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• 제29권5호
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• pp.284-291
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• 2019

본 연구에서는 대면적을 지니는 CDI 모듈의 흐름 향상을 위하여 유체가 들어가는 유입구로부터 면적이 증가하는 직사각형 형태의 유로를 설계하였다. 이를 바탕으로 설계된 모듈 형태에 대해 공급수의 흐름성과 사영역의 유무를 파악하였고 CFD 전산 유체 역학 프로그램을 통해 유로 내의 내부 압력, 유선 그리고 속도 벡터 분포를 분석하였으며 실제 흐름 관측과 CFD 프로그램을 비교 분석하였다. 실험 결과 모든 유속 10, 20, 30 mL/min에서 유로 내 사영역이 거의 발생하지 않았으며 공급수의 흐름성도 일정하게 유지되어 추후 대면적을 가지는 CDI 공정에 적용이 가능할 것이라 판단된다.

• 멤브레인
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• 제27권4호
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• pp.367-373
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• 2017

중공사형 정밀여과(MF)와 한외여과(UF)를 포함한 가압식 막여과 시스템은 높은 수준의 병원균 제거 효율로 인해 음용수 처리에 점점 더 많이 사용되고 있다. 그러나 가압식 막여과 시스템에서 분리막의 손상으로 인한 막완결성의 문제가 발생시 병원체가 유출될 수 있으므로, 효과적인 온라인 또는 오프라인 방식의 막 완결성 모니터링 방법을 통해 수질의 안정성을 보장하여야 한다. 최근 막 완결성 시험 중 하나 인 압력손실시험(pressure decay test, PDT)이 가압식 분리막 모듈을 이용한 음용수 처리 시설에 적용되고 있다. 이 논문에서는 PDT의 기체 주입방법에 따른 세 가지 조건으로 원수 측, 여과수 측, 원수 여과수 양방향 측 세 가지 조건을 선정 후 이에 따른 감지감도를 이론값과 실험값을 적용하여 비교하였다. 실험결과 가압되는 측의 부피와 감도는 반비례함을 확인하였고, 주입부의 반대방향에 부압을 형성 시에도 감도가 증가함을 확인할 수 있다. 즉 막 손상의 감지감도는 주입되는 부분의 체적이 작아질수록, 분리막을 경계로 유입과 여과 측의 압력차가 클수록 높아짐을 알 수 있었다.