• Environmental Engineering Research
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• 제19권1호
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• pp.1-8
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• 2014

Natural organic matter (NOM) is a primary component of fouling in low-pressure membrane filtration, either solely, or in concert with colloidal particles. Various preventive measures to interfere with NOM fouling have been developed and extensively tested, such as coagulation, oxidation, ion exchange, carbon adsorption, and mineral oxide adsorption. Therefore, this article aims to conduct a literature review covering the topics of low-pressure membrane processes, NOM characteristics and fouling behaviors, and diverse fouling control strategies. In-depth explanations and discussion are made regarding why some treatment options are able to remove NOM from source water, but do not reduce fouling. This review provides insight for hybridized membrane processes with respect to NOM removal and fouling mitigation in water treatment.

• Journal of Advanced Marine Engineering and Technology
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• 제40권3호
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• pp.152-156
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• 2016

폐수 열원 히트펌프 시스템은 목욕탕, 공장 또는 하천수 등을 히트펌프의 열원으로 사용한다. 증발기는 폐수로부터의 오염을 완화시키기 위하여 휜이 없는 나관식(bare tube) 열교환기가 주로 사용되고 있다. 대부분의 열 저항은 관외를 흐르는 폐수측에 생성되는 파울링에 의한 것이며, 히트펌프의 성능을 급격하게 감소시킨다. 따라서 본 연구에서는 나관식 열교환기 하부에서 버블 유동층을 형성시키고 세정 볼을 사용하여 관 외측의 파울링을 저감시키는 장치를 개발하였다. 실험 조건으로, 냉수온도 $20^{\circ}C$, 폐수 온도 $40^{\circ}C$, 관 내측 유량 100L/h, 수조 내 물의 양 50L, 열교환기 면적 $0.161m^2$ 이다. 실험결과 세정 볼 없이 버블유동층만 형성한 경우에는 버블유동층이 없는 경우에 비해 파울링에 의해 생성된 열 저항이 약 56% 감소되었으며, 세정 볼의 개수 밀도가 8,000(Number of $ball/m^3$) 일 때, 파울링에 의해 생성된 열 저항은 버블유동층 및 세정 볼이 없을 때와 비교하여 약 86% 감소되었다.

• Membrane and Water Treatment
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• 제8권5호
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• pp.395-409
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• 2017

Membrane bioreactor (MBR) is a compact and efficient wastewater treatment and reclamation technology; but, it is limited by membrane fouling. The control of membrane fouling significantly increases operational and maintenance costs. Bacteria and their byproducts - extracellular polymeric substances (EPS) - are major contributors to membrane fouling in MBRs. A recent attempt at fouling mitigation is the development of aerobic granular sludge membrane bioreactor (AGMBR) through the integration of a novel biotechnology - aerobic granulation - and MBR. This paper provides an overview on the development of AGMBR to mitigate membrane fouling caused by bacteria and EPS. In AGMBR, EPS are used up in granule formation; and, the rigid structure of granules provides a surface for bacteria to attach to rather than the membrane surface. Preliminary research on AGMBR using synthetic wastewater show remarkable membrane fouling reduction compared to conventional MBR, thus improved membrane filtration. Enhanced performance in AGMBR using actual municipal wastewater at pilot-scale has also been reported. Therefore, further research is needed to determine AGMBR optimal operational conditions to enhance granule stability in long-term operations and in full-scale applications.

• 멤브레인
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• 제21권1호
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• pp.46-54
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• 2011

자연유기물을 처리하는 침지형 중공사막 정밀여과 시스템에서 $TiO_2$ 나노입자와 UV를 이용한 광촉매 반응을 적용 시 공기폭기, $TiO_2$ 농도, 용액의 pH 그리고 $Ca^{+2}$의 존재가 자연유기물에 의한 파울링에 미치는 혼합영향을 관찰하였다. 실험결과, $TiO_2$ 나노입자 없이 단순 UV의 조사만으로 자연유기물에 의한 파울링은 약 40% 정도 감소시킬 수 있었다. 또한 UV의 조사 없이 $TiO_2$ 나노입자의 교반만으로 약 25%의 파울링 감소효과를 나타내었다. 공기폭기가 광촉매 반응에 미치는 영향을 확인해 본 결과 공기폭기를 적용해 주지 않은 경우와 비교했을시 공기폭기로 인한 자연유기물의 제거효율은 약 12% 정도 향상되었다. 이는 공기폭기로 인한 분리막 표면으로부터 자연유기물의 물리적인 역수송 보다는 산소공급으로 인해 광촉매 반응이 더욱 향상된 것으로 판단된다. 공기폭기 유량, $TiO_2$ 농도, 용액의 pH 영향정도를 관찰한 결과 공기폭기가 자연유기물 파울링 감소에 미치는 영향이 가장 낮은 것으로 나타났다. 반면, 용액의 pH 경우 낮은 pH (= 4.5)에서 파울링 감소에 미치는 영향이 가장 높은 것으로 관찰되었다. 또한 $TiO_2$ 나노입자 농도가 증가할 수록 파울링 감소효과도 증가하였으며 용액의 pH를 낮출수록 파울링 감소는 증가하였다. 이는 낮은 pH에서 서로 반대전하를 지닌 자연유기물과 $TiO_2$ 나노 입자간의 정전기적인 인력이 증가하여 $TiO_2$ 나노입자 표면에서 자연유기물의 광촉매분해능이 향상된 것으로 사료된다. 또한 자연유기물 중 $Ca^{+2}$의 첨가는 상대적으로 높은 pH (= 10)에서 자연유기물과 $TiO_2$ 나노입자 사이 가교현상을 촉진시켜 $Ca^{+2}$이 첨가되지 않은 경우와 비교시 높은 파울링 감소효과와 자연유기물의 분해효과를 달성시킬 수 있었다.

• Journal of Industrial and Engineering Chemistry
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• 제67권
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• pp.199-209
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• 2018

Polyethersulfone (PES)/sulfonated $TiO_2$ ($STiO_2$) nanoparticles (NPs) UF blended membranes were fabricated with different loadings of $STiO_2$. The modified membranes exhibited significant improvement in surface roughness, porosity, and pore size when compared to the PES membrane. The $P-STiO_2$ 1 and $P-TiO_2$ 1 blended membranes exhibited higher water flux, approximately 102.4% and 62.6%, respectively, compared to PES. SPP-$STiO_2$ and $P-STiO_2$ showed lower Rir fouling resistance than the $P-TiO_2$ blended membrane. Overall, the $STiO_2$-blended membranes provide high hydrophilicity permeability, anti-fouling performance, and improved BSA rejection attributed to the hydrogen bonding force and more electrostatic repulsion properties of $STiO_2$.

• Membrane and Water Treatment
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• 제8권6호
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• pp.543-551
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• 2017

Membrane fouling in membrane bioreactor (MBR) remains a primary challenge for its wider application. The focus of this study to investigate the influence of iron distribution in activated sludge on gel layer fouling in MBR. Significant reduction in the transmembrane pressure (TMP) rise rates was observed in the presence of iron as result of retarding the gel layer formation time. The spatial distribution of iron had a significant impact on the stratification structure of extracellular polymeric substances (EPS) fractions, such as proteins (PN) and polysaccharides (PS). A mitigation of PN or PS from the supernatant to the EPS inner layers was observed in the presence of iron. Compared with the control reactor, the reduction in PN and PS of the supernatant and lower PN/PS rates of the LB-EPS were beneficial to decrease the membrane fouling potential during the gel layer formation. Consequently, the iron addition managed to control gel layer fouling could be a useful strategy in MBR.

• 한국막학회:학술대회논문집
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• 한국막학회 2001년도 춘계 총회 및 학술발표회(한국막학회)
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• pp.128-131
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• 2001

• 한국막학회:학술대회논문집
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• 한국막학회 2001년도 추계 총회 및 학술발표회(한국막학회)
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• pp.107-110
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• 2001

• Membrane and Water Treatment
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• 제13권1호
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• pp.39-49
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• 2022

Seawater desalination is doubtlessly a viable option to supply fresh drinking water. Nevertheless, RO (reverse osmosis) desalination plants in specific areas may be intermittently operated to match the imbalance between water demand and supply. Although a handful of works have been done on other membrane systems, few studies have attempted to mitigate fouling in intermittent RO systems. Accordingly, the objectives of this paper were to examine the effect of the intermittent operation on RO fouling; and to compare four intermittent operation modes including feed solution recirculation, membrane storage in the feed solution, deionized water (DI) recirculation, and membrane storage in DI water. Results showed that intermittent operation reduced RO fouling under several conditions. However, the extents of fouling mitigation were different depending on the feed conditions, foulant types, and membrane lay-up methods. When the feed solution was recirculated during the lay-up, the restoration of the flux was less significant than that by the feed solution feed-up. The use of deionized water during the lay-up was effective to restore flux, especially when the feed solution contains scale-forming salts (CaSO₄) and/or colloidal silica.

• 상하수도학회지
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• 제32권2호
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• pp.77-87
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• 2018

In this study, the effects of operating conditions on the formation of reversible and irreversible fouling were investigated in the filtration using ceramic membrane for water treatment process. The effect of coagulation pretreatment on fouling formation was also evaluated by comparing the performance of membrane filtration both with and without addition of coagulant. A resistance-in-series-model was applied for the analysis of membrane fouling. Total resistance (RT) and internal fouling resistance (Rf) increased in the membrane filtration process without coagulation as membrane flux and feed water concentrations increased. Internal fouling resistance, which was not recovered by physical cleaning, was more than 70% of the total resistance at the range of the membrane flux more than $5m^3/m^2{\cdot}day$. In the combined process with coagulation, the cake layer resistance (Rc) increased to about 30-80% of total resistance. As the cake layer formed by coagulation floc was easily removed by physical cleaning, the recovery rate by physical cleaning was 54~90%. It was confirmed from the results that the combined process was more efficient to recover the filtration performance by physical cleaning due to higher formation ratio of reversible fouling, resulted in the mitigation of the frequency of chemical cleaning.