• 상하수도학회지
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• 제23권4호
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• pp.459-469
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• 2009

It is well known that coagulation pretreatment can reduce foulants prior to membrane filtration. The purpose of this research was to investigate the effects of coagulation on fouling of ceramic microfiltration membrane($0.1 {\mu}m$) using pilot plant of $150m^3/day/train$ capacity. Train A membrane system has pretreatment process of ozonation and coagulation while train B has only coagulation. Two types of coagulation operation were investigated: back mixer(rapid mixing with or without slow mixing) which is a conventional mechanically stirred mixer and an inline static mixer. Ozone dose rate for train A was 1 mg/L and ozone contact time was 12 min. The coagulation dose(PACl 10% as $Al_2O_3$) rate was changed 20~40 mg/L according to experimental schedule. In this experimental conditions, the coagulation of back mixer type with rapid mixing(GT=72,000) and slow mixing(GT=45,000) was the best effective in reduction of ceramic membrane fouling regardless preozonation. Especially, the effect of inline static mixer was sensitive to change in water quality. Ozonation mainly affected irreversible fouling rather than reversible fouling in accordance with less adsorption of NOM on the membrane surface. Thus, the increase rate of the nomalized TMP(trans membrane pressure) at $25^{\circ}C$ for train A was relatively lower than that of train B under same coagulation process with same coagulant dosage. The best performance of ceramic membrane appeared in case of combined process with ozonation, therefore this integrated process is able to archive less coagulant dosing and secure a stability of ceramic membrane system.

• 멤브레인
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• 제12권1호
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• pp.28-40
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• 2002

본 연구는 복합 박막 활성층의전기적/분자 구조적인 특성이 오염성에 어떤 영향을 미치는가를 조사하였다. 복합 박막 형태의 폴리아미드계 역삼투 분리막에 대한 오염 거동 현상을 이해하는데 있어 표면 구조와 표면 전하의 연구는 매우 효과적이다. AFM 전자현미경을 이용한 표면 구조 분석과 EKA 전위차 측정기를 통한 표면 전하의 분석 결과는 역삼투 분리막의 오염에 영향을 미치는 중요한 인자를 보여주고 있다. 복합막의 활성층이 중성에 가까울수록, 조도 차가 작을수록 역삼투막의 유량 감소 속도는 줄어든다.

• 멤브레인
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• 제8권4호
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• pp.210-219
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• 1998

Fouling을 줄이기 위한 한외여과용 친수성 막을 제조하기 위해서 chlorosulfonic acid(CSA)를 사용하여 이온교환용량이 다른 여러 종류의 sulfonated polyethersulfone(SPES)을 불균일계에서 제조하고 특성조사를 하였다. CSA농도, 반응온도, 반응시간 등의 반응조건에 따른 반응도와 분해정도를 알아본 결과 10$\circ$C 이상의 온도와 0.05 mol 이상의 CSA 농도에서 효과적으로 반응이 일어나지만 고분자 주쇄의 분해가 심하게 일어나는 경향을 나타내었다. 술폰산기의 치환여부는 FTIR과 $^1$H-NMR로 확인할 수 있었다. 불균일계에서 개질된 SPES 한외여과막의 단백질에 의한 fouling 감소효과를 알아보기 위해 같은 투과성능을 갖는 막을 비용매인 DCM과 pore 형성제 PVP를 첨가제로 사용하여 막을 제조하였다. 이온교환용량이 증가함에 따라 투과속도는 감소하고 배제율은 상당히 증가되었다. 이런 결과는 SEM에 의해서도 확인할 수 있었다. Finger 구조가 사라지면서 top layer의 두께도 증가하였다. 비용매인 DCM에 의해서 치밀한 막을, pore 형성제인 PVP에 의해서 다공성 막을 제조할 수 있었다. 이온교환 용량이 높을수록 친수성이 증가하여 fouling을 감소시킬 수 있었다.

• Membrane and Water Treatment
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• 제6권2호
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• pp.161-172
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• 2015

Forward osmosis (FO) is an emerging membrane technology with potential applications in desalination and wastewater reclamation. The osmotic pressure gradient across the FO membrane is used to generate water flux. In this study, flux performance and foulant deposition on the FO membrane were systematically investigated with a co-current cross-flow membrane system. Sodium alginate (SA), bovine serum albumin (BSA) and tannic acid (TA) were used as model foulants. Organics adsorbed on the membrane were peeled off via oscillation and characterized by Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM). When an initial flux of $8.42L/m^2h$ was applied, both flux reduction and foulant deposition were slight for the feed solution containing BSA and TA. In comparison, flux reduction and foulant deposition were much more severe for the feed solution containing SA, as a distinct SA cake-layer was formed on the membrane surface and played a crucial role in membrane fouling. In addition, as the initial SA concentration increased in FS, the thickness of the cake-layer increased remarkably, and the membrane fouling became more severe.

• Membrane and Water Treatment
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• 제10권6호
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• pp.461-469
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• 2019

In the present work, we present a new effective hydrophilicity modifier for polysulfone (PSf) membrane. Firstly, amphiphilic nanocellulose (ANC) with different substitution degrees (SD) was synthesized by esterification reaction with nanocellulose (NC) and dodecyl succinic anhydride (DDSA). The SD and morphology of ANC were characterized by titration method and transmission electron microscopy (TEM). Then, the polysulfone (PSf)/ANC blend membranes were prepared via an immersion phase inversion method. The influence of SD on the morphology, structure and performances of PSf/ANC blend membrane were carefully investigated by Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), mechanical property test, contact angle measuring instrument and filtration experiment. The results showed that the mechanical property, hydrophilicity and anti-fouling property of all the PSf/ANC blend membranes were higher than those of pure PSf membrane and PSf/NC membrane, and the membrane properties were increased with the increasing of SD values. As ANC-4 has the highest SD value, PSf/ANC-4 membrane exhibited the optimal membrane properties. In conclusion, the prepared ANC can be used as an additive to improve the hydrophilicity and anti-fouling properties of polysulfone (PSf) membrane.

• 한국물환경학회지
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• 제22권1호
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• pp.140-144
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• 2006

This study was performed to investigate the effect of organic characteristics and feed water solution chemistry on membrane fouling index such as Silt Density Index (SDI) and Modified Fouling Index (MFI). Specifically, Aldrich humic acids (AHA) and Suwannee river humic acids (SHA) were used in SDI/MFI experiments. Higher SDI values were observed with increasing organic concentration. AHA with larger molecular weight (MW) and SUVA (${\approx}UV_{254}/TOC$) resulted in higher SDI values, compared to SHA. The feed solution chemistry (i.e, pH, ionic strength, and hardness) also affects SDI values to some degree. In particular, SDI increased with increasing hardness ($Ca^{2+}$) concentration for AHA. Unlike SDI, the MFI developed on the basis of particle cake filtration theory, was not accurately assessed due to internal fouling by organics such as pore adsorption and subsequent pore blocking.

• 멤브레인
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• 제21권2호
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• pp.163-170
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• 2011

수처리 분리막 공정에서 막 오염 제어 기술은 현장 적용 기술 및 경제성 확보에 있어 매우 중요하다. 본 연구에서는 형광 나노 입자 및 형광 분광 분석법을 도입함으로써 수처리 분리막 공정에서 막 오염 정도를 실시간으로 측정 모니터링 할 수 있는 센싱 기술을 개발하고자 하였다. 막 오염 정도를 모니터링 할 수 있는 분리막 제조를 위해 세 종류의 형광물질 OB, FP, KCB를 담지한 다공성 polysulfone (PSf) 비대칭 막을 제조하였다. 형광 분광 분석 시스템을 이용하여 분리막 표면에서의 오염 정도를 실시간으로 측정한 결과, 형광 물질을 첨가한 막은 막 오염이 진행됨에 따라 형광 신호가 크게 감소함을 보여 막 표면 오염층의 모니터링 분석이 가능함을 확인하였다.

• 멤브레인
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• 제24권3호
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• pp.249-257
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• 2014

본 실험은 실험실적 규모의 침지식 평막형 분리막이 장착된 활성슬러지 생물반응기에 인공폐수를 사용하여 수행하였다. 분리막 운전은 MLSS 5,000 mg/L 활성슬러지 용액을 일정 유량으로 계속 투과시키는 방식과 주기적으로 10분여과/2분휴지 방식으로 구분하여 실시하였다. 산기량은 0.25 L/min로 일정하게 유지한 상태에서 투과유속을 10에서 $25L/m^2{\cdot}hr$까지 증가시키면서 막간차압을 측정하였다. 또한 분리막 오염 상태를 판단하기 위하여 완전막힘, 표준막힘, 중간막힘, 비압축성 케이크 및 선형압축성 케이크 오염 모델을 실험값에 적용하였다. 10분운전/2분휴지 운전방식에서는 매 주기마다 펄스형태로 막간차압이 변화하므로 최고점 및 최저점 연결선으로 구분하여 막오염 모델을 적용하였다. 활성슬러지 케이크 막오염은 이상의 5가지 오염 모델 중 선형압축성 케이크 오염 모델이 모든 투과실험 결과와 가장 잘 일치하였다.

• Membrane and Water Treatment
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• 제10권4호
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• pp.277-286
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• 2019

In 2014, the first demineralization plant, using nanofiltration (NF) membrane coupled with renewable energies was realized at Al Annouar high school of Sidi Taibi, Kenitra, Morocco. This project has revealed difficulties related to the membrane performances loss (pressure increase, flux decline, poor water quality of the produced water and increase of energy consumption), as consequences of membrane fouling. To solve this problem, an autopsy of the membrane was done in order to determine the nature and origin of the fouling. The samples of membrane and fouling were then analyzed by scanning electron microscopy using a scanning electron microscope (SEM) connected with an energy dispersive X-ray (EDX) detection system and X-ray diffractometer (XRD). Moreover, three cleaning solutions (hydrochloric acid, nitric acid and sulfuric acid) were tested and assessed in a single cleaning step to find the suitable one for the fouled membrane to regain its initial permeability and performances. The analysis of the experimental results showed that the fouling layer is mainly composed of calcium carbonate (inorganic fouling). Results showed also that the permeability is improved by the hydrochloric acid cleaning (pH=3) with a cleaning efficiency of 93%. Cleaning efficiency did not exceed 75 % with nitric acid (pH=3) and 40 % with sulfuric acid (pH=3).

• Membrane and Water Treatment
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• 제1권3호
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• pp.193-206
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• 2010

Organic fouling and biofouling pose a significant challenge to the membrane filtration process. Photocatalysis-membrane hybrid system is a novel idea for reducing these membranes fouling however, when $TiO_2 photocatalyst nanoparticles are used in suspension, catalyst recovery is not only imposes an extra step on the process but also significantly contributes to increased membrane resistance and reduced permeate flux. In this study, $TiO_2$ photocatalyst has been immobilized by coating on the microfiltration (MF) membrane surface to minimize organic and microbial fouling. Nano-sized $TiO_2$ was first synthesized by a sol-gel method. The synthesized $TiO_2$ was coated on a Poly Vinyl Difluoride (PVDF) membrane (MF) surface using spray coating and dip coating techniques to obtain hybrid functional composite membrane. The characteristics of the synthesized photocatalyst and a functional composite membrane were studied using numerous instruments in terms of physical, chemical and electrical properties. In comparison to the clean PVDF membrane, the $TiO_2$ coated MF membrane was found more effective in removing methylene blue (20%) and E-coli (99%).