• Title/Summary/Keyword: Specific cake resistance

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Effect of Porous Filter Structure on Specific Cake Resistance and Porosity in Dead-end Filtration (Dead-end Filtration에서 Dust Cake 비저항과 기공율에 대한 다공성 필터 구조의 영향)

  • 이선희;조영민;유정근
    • Proceedings of the Korea Air Pollution Research Association Conference
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    • 2003.05b
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    • pp.405-406
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    • 2003
  • 분진여과시 형성되는 분진 케이크는 궁극적인 여과 성능을 좌우하며, 필터의 구조, 분진 입자의 형태나 크기, 분진농도, 여과속도 등에 의해 영향을 받는다 특히 필터의 표면 구조나 기공 크기는 여과 초기 단계의 케이크 층의 구조를 결정하며, 연속적인 여과시 초기 케이크 층은 다음에 쌓이는 케이크 형성과 비저항에 영향을 주므로 필터 medium 구조 또한 분진여과 과정에서 중요한 영향 요인이 된다. 본 연구에서는 필터 medium의 구조가 서로 다른 고온가스정화용 복합 세라믹 필터, metal fiber mat, 스테인레스 필터를 이용하여 분진농도와 여과속도를 변수로 하여 분진 여과 실험을 함으로써 각각의 필터에 대한 케이크 비저항과 기공율을 실험과 이론식으로부터 추정하였다. (중략)

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Impact of Characteristics of Polymeric Al Coagulants PACl and Alum on Membrane Flux and Fouling of Microfiltration (PACl 및 Alum 응집제 특성이 정밀여과막 투과수량 및 막오염에 미치는 영향)

  • Jin, Yong-Chul;Choi, Yang-Hun;Kweon, Ji-Hyang
    • Journal of Korean Society of Water and Wastewater
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    • v.25 no.2
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    • pp.231-240
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    • 2011
  • The objectives of this research are to investigate coagulation efficiencies of two coagulants l.e., alum and polyaluminum chloride and to understand effects of the coagulants on membrane fouling in microfiltration. The turbidity of supernatant from alum coagulation was increased with increasing doses whereas the turbidity from PACl coagulation was maintained at the low values. The observed injection volume of PACl for the same removal was approximately 30 percent less than alum, which produced a low sludge volume. The settling velocity of PACl flocs was greater than alum flocs. The results corresponded well with floc size measurements. Flux decline from alum coagulation was significant due in part to small sizes of flocs. At the low dose, alum floc had less specific cake resistance than PACl floc. However, as the dosage was increased, the increases in specific cake resistances of alum was substantial. Alum coagulation pretreatment needs careful operation to reduce membrane fouling by flocs. In general, PACl coagulants were more effective than alum coagulants for pretreatment of membrane processes because PACl showed the better performance in coagulation and membrane fouling.

The Properties of Yellow Layer Cakes Made by Different Substituting Levels of Waxy Maize Starch for Shortening (Waxy Maize Starch의 대체율을 달리하여 제조한 옐로우 레이어 케이크의 특성)

  • 송은승;강명화
    • Journal of the East Asian Society of Dietary Life
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    • v.14 no.1
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    • pp.39-46
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    • 2004
  • Waxy maize starches are inherently stable in soluble status and can be chemically modified to improve stability along with heat, acid and shear resistance. This study was carried out to investigate the effect of theological and sensory characteristics of the yellow layer cake made by adding different levels of waxy maize starch as a fat substitute for shortening. By increasing the substitution level of waxy maize starch for shortening, the specific gravity of cake batter increased and the viscosity decreased. The microstructures of cake crumb observed by the scanning electron microscope were not different significantly, and the size of air cells and fat particles also were not substantially decreased by increasing fat substitution level. The texture profile analysis using texture analyzer decreased by increasing the different substituting levels of waxy maize starch. Among various sensory properties, the color value of layer cake increased by increasing the level of waxy maize starch. However, the appearance, flavor, taste, texture and overall preference decreased.

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The Reduction of Waterworks Sludge by Hydrogen Peroxide Treatment (과산화수소 산화처리에 의한 정수슬러지의 감량화)

  • Kwon, Jae-Hyun;Kim, Young-Do;Park, Ki-Young;Lee, Seock-Heon;Kim, II-Kyu
    • Journal of Korean Society of Water and Wastewater
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    • v.21 no.1
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    • pp.123-130
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    • 2007
  • The effects of hydrogen peroxide treatment on the reduction of waterworks sludge were investigated in this study. Sludge treated by peroxidation $H_2O_2$ oxidation) was dewatered using a pressure filter at 3atm. It was observed that $H_2O_2$ treatment at the acidic condition significantly reduce both cake water content and specific resistance to filtration (SRF), indicating the enhancement of dewaterability and filterability. The filterability by hydrogen peroxide treatment at pH 3.5 was better than acidic treatment and became comparable with polymer conditioning. The sludge filterability evaluated by SRF was optimal at a dose 2ml $H_2O_2$/sludge($0.02g\;H_2O_2/gTS$) after adjusting of pH to 3.5. The $H_2O_2$ oxidation at pH 3.5 also produced even more dewatered cake when compared with polymer conditioning. The reduction rate of sludge mass at an optimal condition showed 34% compared with untreated sludge. The effects of peroxidation on sludge properties including zeta potential, bound water and particle size were also evaluated. Peroxidation at the acidic condition reduced both bound water and zeta potential. By $H_2O_2$ combined with sulfuric acid leached iron caused Fenton's reaction, which showed a potential to significantly reduce the amount of solids mass and to produce more compact cake with higher filterability.

Performance Evaluation of Gas Cleaning Industrial Filters using a Bi-Modal Test Aerosol for Dust Loading Studies

  • Lee, Jae-Keun;Kim, Seong-Chan;Benjamin Y.H. Liu
    • Journal of Energy Engineering
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    • v.5 no.2
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    • pp.131-137
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    • 1996
  • Typical size distribution of emission particulates is bi-modal in shape with particles in the fine mode (< 2.0 $\mu\textrm{m}$) and the coarse mode. An experimental study of pressure drop across the industrial gas cleaning filters has been conducted using particle mixture of fine alumina and coarse Arizona dusts with a rotating aerosol disperser to generate the bi-modal test aerosol. Pressure drop increased linearly with increasing mass loading. The pressure drop was found to be strongly dependent upon the mass ratio of fine to coarse particles. The smaller the mass ratio of fine to coarse particles and the higher face velocity are, the faster pressure drop rises. The fine particles and the greater inertia of the particle moving fast would cause a denser cake formation on the filter surface, resulting in a greater specific resistance to the gas flow.

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Study on the Improvement of Paper Sludge Dewatering by Adding Wastepaper Powders (고지 분말 첨가에 따른 제지 슬러지의 탈수성 개선에 관한 연구)

  • 이성호;임택준;조준형
    • Journal of Korea Technical Association of The Pulp and Paper Industry
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    • v.34 no.2
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    • pp.47-53
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    • 2002
  • Three types of sludges including printing paper, newsprint and tissue paper were prepared at 5% concentration for filtration-expression operations. Filtration-expression characteristics of sludge were measured in different pressure and wastepaper powder dosage. Specific filtration resistance and porosity were calculated with theoretical formula. Higher pressure increased the progresses of filtration and expression while it decreased porosity. The addition of 5% wastepaper powder more accelerated the progresses of filtration and expression than that of 10% wastepaper powder. The lowest porosity value was also measured at 5% dosage of wastepaper powder. The decrease of porosity implied the decrease of moisture content in cake. The results indicated that dewatering of sludge was efficient in high pressure and 5% dosage of wastepaper powder.

Influences of Detention Time, Particle Size Distribution, and Filter Medium on Waterworks Sludges Dewatering (체류시간, 입도분포 및 여재가 정수 슬러지의 탈수에 미치는 영향)

  • Kim, Kwang-Soo;Lee, Jae-Bok
    • Journal of Korean Society of Water and Wastewater
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    • v.23 no.1
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    • pp.121-128
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    • 2009
  • Objectives of this study were to investigate influencing factors of detention time, particle size distribution, and filter medium characteristics for waterworks sludge dewatering. The stepped pressure filtration was carried out with lab scale apparatus and the filter press pilot test for dewatering was conducted at the water treatment plant. Effects of filter medium and polymer dose were examined through observing water content and dewatering velocity and cyclic dewatering rate with filter press pilot test. Relationships among detention time, particle size distribution and filtration resistance were analyzed. Prolongation of sludge detention time was found to cause blinding phenomenon in cake and filter medium and to decrease dewatering process efficiency. The average specific resistance increased according to detention time. In pilot test of dewatering for thickened sludge with Nylon Multi-NY840D and Nylon Mono-100% filter media, dewatering velocities were 0.92 and $0.93kg\;DS/m^2{\cdot}hr$ according to 0.1% polymer dose of dried solids weight base. And cyclic dewatering rates were 2.45 and $2.50kg\;DS/m^2{\cdot}cycle$ cycle for the Nylon Multi-NY840D and Nylon Mono-100% media. Dewatering velocity of polymer dosed sludge was observed to be higher than that of non-polymer sludge.

Effect of Inorganic Particles on Organic Fouling in Pressurized Membrane Filtration (가압식 분리막 여과에서 무기입자의 존재가 유기파울링에 미치는 영향)

  • Jang, Hoseok;Kim, Jeonghwan
    • Membrane Journal
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    • v.30 no.2
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    • pp.131-137
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    • 2020
  • In this study, effect of inorganic particles on organic fouling was investigated by a laboratory-scaled pressurized membrane filtration. In order to cause organic fouling, sodium alginate (SA) was used as a feed solution. Regardless of the presence of inorganic SiO2 particles, the complete pore blocking played an important role in determining the fouling rate during the initial period of membrane filtration. However, the formation of cake layer resulted in the membrane fouling more dominantly as filtration time progressed. In the presence of inorganic particles, both specific cake resistance and compressibility associated with the membrane fouling formed were relatively lower than that without SiO2 particles. Membrane fouling was more severe at constant flux mode of filtration than that observed at constant pressure mode probably due to the concomitant increase of compressibility of fouling layer with transmembrane pressure (TMP). It was found that the presence of SA and SiO2 particles in feed solution provided the synergistic effect on the hydraulic backwashing to reduce membrane fouling as compared to the SA solution alone without the inorganic particles.

Effects of EPS on membrane fouling in a hybrid membrane bioreactor for municipal wastewater treatment

  • Zhang, Aining;Liu, Zhe;Chen, Yiping;Kuschk, Peter;Liu, Yongjun
    • Membrane and Water Treatment
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    • v.5 no.1
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    • pp.1-14
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    • 2014
  • A pilot-scale hybrid membrane bioreactor (HMBR) for real municipal wastewater treatment was developed by adding biofilm carriers into a conventional membrane bioreactor, distribution and dynamic changes of the extracellular polymeric substances (EPS) and their roles in membrane fouling were investigated. The results showed that the concentrations of loosely bond EPS (LB-EPS) and tightly bond EPS (TB-EPS) in activated sludge, carrier biofilm and sludge cake layer have been increased significantly with the running time of HMBR, during operation of the HMBR, EPS demonstrated positive correlations with membrane fouling. Compared to TB-EPS, LB-EPS showed more significant correlations with sludge physical properties and specific resistance to filtration (SRF) in HMBR, and thus demonstrated that LP-EPS have a stronger potential of fouling than TB-EPS. It was also found that a lower organic loading in HMBR could result a significant increase in EPS concentration, which would in turn influence membrane fouling in HMBR. This critical investigation would contribute towards a better understanding of the behavior, composition and fouling potential of EPS in HMBR operation.

Effect of Fouling Reducing Additives on Membrane Filtration Resistance of Activated Sludge (막오염 감소제가 활성슬러지의 여과저항에 미치는 영향)

  • Chung, Tai Hak;Lee, Jong Hoon;Kim, Hyoung Gun;Bae, Young Kyoung
    • Journal of Korean Society of Environmental Engineers
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    • v.34 no.6
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    • pp.406-413
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    • 2012
  • Effect of three additives, chitosan, ferric chloride, and MPE50 on membrane fouling reduction was studied. They were introduced with various dosing rate into activated sludge, and changes in filtration resistance measured by the batch cell filtration test were evaluated. Both the filtration resistance and the specific cake resistance were minimized at 20 mg/g-MLSS with chitosan, 70 mg/g-MLSS with ferric chloride, and 20 mg/g-MLSS with MPE50 addition, respectively. Introduction of the additives into the activated sludge resulted in reduction of not only cake resistance, but also fouling resistance. However, the chitosan addition to three different activated sludge resulted in three different optimal dose of 10, 20, 30 mg/g-MLSS, respectively. This implies that the optimal dose is dependent on sludge characteristics rather than a constant value. Overdose above the optimal dosage always aggravated filterability in all cases. Zeta potential of sludge flocs, relative hydrophobicity, floc size distribution, soluble EPS concentration and supernatant turbidity were measured in order to analyze fouling reduction mechanism. Nearly neutral surface charge along with the largest particle size was observed at the optimal dose. This could be explained by particle destabilization and restabilization mechanism as positively charged additives were injected into sludge flocs of negative surface charge. Both soluble EPS concentration and supernatant turbidity also showed the lowest value at the optimal dose. These foulants are believed to be coagulated and entrapped in sludge flocs during flocculation. Chitosan and MPE50 which are cationic polymeric substances showed higher reduction in both soluble EPS and fine particles comparing with ferric chloride.