• Korean Chemical Engineering Research
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• 제43권6호
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• pp.696-703
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• 2005

케이크 여과에서 케이크에 대한 정의가 아직 마련되어 있지 않다. 특히 침전된 플럭(floc)의 여과에서는 케이크를 전혀 정의하지 못하였다. 본 연구에서는 '여과-투과(filtration-permeation)' 실험을 사용하여 모든 경우의 케이크를 명확히 정의하였다. 이 케이크의 정의에 대한 고찰을 통해 케이크 여과에 의해 이룩될 수 있는 케이크 함수량의 한계에 대한 연구를 수행하였다. 여과에 의해 형성된 케이크의 수분 함량을 줄이기 위한 압착조작(expression) 과정을 '고액분리 통합이론'으로 계산하고 실제 압착조작 데이터와 비교하였다. 여과와 압착조작 전체를 분석하여, 압착의 중요성을 검토했다. 그리고 회분식으로 조작되는 필터 프레스의 케이크 배출과 세척시간을 포함하여 가장 효율적인 조작조건을 계산하는 방법을 제안하였다.

• 멤브레인
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• 제16권3호
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• pp.182-187
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• 2006

본 연구에서는 침지형 MBR 공정에서 인제거를 위해 주입되는 응집제가 분리막의 여과성능에 미치는 영향을 알아보고자 하였고, 침지형 MBR에서 분리막 표면의 오염을 방지하기 위해 연속적으로 행하는 폭기가 응집 플록에 미치는 영향을 조사하고자 하였다. 이를 위해 MBR공정의 폭기조 슬러지를 채취하여 jar-test를 실시한 결과와 비교하였다. 실험 결과는 플록 크기와 슬러지 탈수성의 지표로서 비여과저항(SRF, Specific Resistance of Filtration)을 측정하여 비교하였다. 응집제 주입량이 증가할수록 $10{\mu}m$ 이하의 플록의 비율이 저감되었으며 탈수성이 증가하였다. 그러나 jar-test 결과와 비교하였을 때, 폭기의 전단력에 의해 그 효과가 저감된 것을 알 수 있었다. 응집제를 주입한 경우 주입하지 않은 경우보다 운전지속시간이 연장되었다 운전지속시간이 응집제 주입량에 비례하여 증가하지는 않았는데, 이는 연속적인 폭기의 전단력으로 인해 $10{\mu}m$ 이하의 입자가 충분히 저감되지 않았기 때문인 것으로 생각된다. 또한 응집제 주입량이 과도하면 오히려 여과저항을 증가시키는 결과를 초래하는 것을 알 수 있었다.

• 한국수처리학회지
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• 제26권6호
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• pp.61-72
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• 2018

In this study, applicability of the decentralized water supply system were investigated by the high flux evaluation using ceramic membrane with combined pretreatment process. A) filtration process increased the transmembrane pressure of 1.4 kPa and 89.5 kPa on 2 and $5m^3/m^2{\cdot}d$ of filtration flux, respectively, the physical backwashing recovery rate were less than 28.6%. The (B) Coag./Floc. - Sedi. combined process with 4 mg / L of A-PAC showed that the transmembrane pressure increased to within 6 kPa, the physical backwashing recovery rate was over 37.9 % higher than (A) Filtration process. (C) Coag./Floc. combined process showed an increase of transmembrane pressure compared with (B) Coag./Floc. - Sedi. combined process, physical backwashing recovery rate was over 84%. As a result of the membrane fouling analysis using the resistance in series model, the combined pretreatment process showed that the cake resistance (Rc) was more than 92% at membrane filtration flux of $2m^3/m^2{\cdot}d$. In the (C) Coag./Floc. combined process, cake resistance(Rc) was over 86% on high flux conditions. The coagulation floc contained in influent was removed by the membrane, and the cake layer formed with the removed floc was identified as reversible fouling resistance which could be recovered by physical backwashing. The decentralized water supply system, which has the limitation of site area and installation space, is considered to could be operation of high flux of ceramic membrane by applying (C) Coag./Floc. combined process without sedimentation process.

• Membrane and Water Treatment
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• 제8권2호
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• pp.185-199
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• 2017

Low-pressure membrane filtration is increasingly used for tertiary treatment of wastewater effluent organic matter (EfOM), mainly comprising organic base/neutral compounds. In-line coagulation with underdosing, charge neutralization, and sweep floc conditions prior to ultrafiltration (UF) was studied to determine removals of the EfOM components and consequent reduction of fouling using polyethersulfone membranes. Coagulation and UF substantially reduced fouling for all coagulation conditions while removing from 7 to 38% of EfOM organic acids. From 7 to 16% of EfOM organic base/neutrals were removed at neutral pH but there was no significant removal for slightly acid coagulation conditions even though fouling was substantially reduced. Sweep floc produced the lowest resistance to filtration but may be inappropriate for in-line use due to the large added volume of solids. Charge-neutralization resulted in poor recovery of the initial flux with hydraulic cleaning. Under-dosing paralleled sweep floc in reducing hydraulic resistance to filtration (for sub-critical flux) and the initial flux was also easily recovered with hydraulic cleaning. Hydrophobic and hydrophilic base/neutrals were identified on the fouled membranes but as previously reported the extent of fouling was not correlated with accumulation of organic base/neutrals.

• 대한환경공학회지
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• 제30권2호
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• pp.161-167
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• 2008

본 연구에서는 새로운 여과-투과(filtration-permeation) 실험 방법을 사용하여 여과실험에 영향을 미치는 인자 중 침전에 대한 영향을 입자현탁액과 플럭현탁액에 대해 각각 수행하였다. 그 결과 여과실험으로는 정확한 평균 비저항값을 예측할 수 없었으나, 투과실험으로 정확한 평균 비저항값을 측정할 수 있었다. 투과기간을 연장하였을 때 입자현탁액에서 형성된 케이크에서는 투과속도에 별다른 영향이 없었으나 플럭현탁액의 경우는 응집제의 쓸려나감 현상을 보였다. 또한 여과-투과 실험을 사용하여 투과시에 단계적으로 압력을 증가시킴으로써 단 한번의 실험에 의해 케이크의 압축성이 측정되어 질 수 있음을 보였으며, 이 방법을 응용하여 평균 비저항값이 큰 활성슬러지의 긴 여과시간을 짧게 줄여 측정하는 새로운 방법을 제안하였다.

• Korean Chemical Engineering Research
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• 제50권2호
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• pp.334-342
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• 2012

새로 개발된 '고액분리 통합이론'의 핵심 개념인 '케이크 첫 입자층이 받는 압력 $p_d$'의 역할을 인식하기 위해, 고압축성 케이크에 대해 다음과 같은 세 가지 고액분리 분야를 새로운 개념으로 분석하였다. 첫째, 침전된 플럭의 케이크 여과에서 여과 대상이 되는 침전 플럭의 두께 계산에서 $p_d$의 역할과, 케이크의 형성 두께 계산에서의 $p_d$의 역할. 둘째, 압착 과정에서의 $p_d$의 역할, 그리고 마지막으로 간섭침전 결과 쌓이는 높이에 미치는 $p_d$의 역할과 간섭침전 과정에서의 $p_d$의 중요성을 보였다. 이로써 고액분리 통합이론의 적용 가능성과, 그에 있어 $p_d$의 중요성을 밝힐 수 있었다. 이 과정을 통하여 케이크 여과, 압착, 간섭침전의 이론적인 새로운 정의가 가능해졌다.

• 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.

• 펄프종이기술
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• 제36권2호
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• pp.10-16
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• 2004

Structures and strengths of paper have been studied by analyzing fibers characteristics depending on refining methods. Mixing ratio of softwood and hardwood fibers and fibers characteristics have been analyzed for paper quality improvement. In this study flocculation and drainage of fibers were analyzed to improve the production efficiency and paper product's quality. Floc size and drainage rate depending on stock consistency and fines content were analyzed. Total amount of drainage during drainage process was measured quantitatively by using DI(drainage index). Floc size, viscosity of floc and dewatering times were also measured. In the case of refining load $2.8 kg_f$ , drainage was occurred by filtration mechanism rather than thickening mechanism because drainage resistance increased by fibrillation of fibers. Therefore, the drainage rate of $2.8 kg_f$ refining load stock was slower than that of $5.6 kg_f$.

• 상하수도학회지
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• 제22권3호
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• pp.281-288
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• 2008

Cake resistance is influenced by floc size deposited on membrane surface. Enlarging floc size can reduce cake resistance. The small particles are enlarged by coagulation and flocculation process in conventional mixing tank at membrane filtration system. Fully-grown flocs for reducing the cake resistance, however, are ruptured while passing through a pump. In light of this fact, this study aims to experimentally look at the reaggregation phenomenon of mixing system. In addition, reaggregation phenomenon of mixing system is compared with first-aggregation of in-line injection system in which coagulant is injected just before a pump. These results suggest that first-aggregation of in-line injection system is better than reaggregation of mixing system for G-value above $3100sec^{-1}$. Since G-value in pipe of actual membrane filtration system are usually larger than $3100sec^{-1}$. The performance of in-line injection system is expected to be better than the conventional mixing tank system.

• 상하수도학회지
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• 제18권6호
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• pp.785-793
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• 2004

Coagulation has been investigated for pretreatment of low-pressure membrane systems such as microfiltration and ultrafiltration. Coagulation pretreatment can reduce foulants (particles and organic matter) prior to membrane filtration. However, when in-line coagulation or submerged type of filtration is used, flocculent aggregates could act as a foulant depending on concentrations and specific properties of floc. A natural water and three synthetic waters were used to investigate effects of coagulation pretreatment and presence of flocculent aggregates on membrane fouling. Coagulation pretreatment shows that foul ants were effectively removed during coagulation and the formed cake layer on the membrane surface had less resistances compared to raw natural water. In addition, little difference in membrane fouling was found by flocculent aggregates from the natural water. Interestingly, however, the results by three synthetic waters indicated that flocculent aggregates could have adverse effects on membrane fouling in a specific condition.