• Title/Summary/Keyword: Floc Filtration

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Study on the Limit of Water Content by Cake Filtration and Effective Operation in Filtration-Expression Process (여과에 의한 케이크 함수량의 한계와 효율적인 여과-압착 조작 조건에 대한 연구)

  • Yim, Sung Sam;Song, Yun Min
    • Korean Chemical Engineering Research
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    • v.43 no.6
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    • pp.696-703
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    • 2005
  • The definition of cake is not established for cake filtration, and especially the definition was impossible for the filtration of the floc already sedimented. The definition is proposed with the experimental method named 'filtration-permeation'. The limit of water content which can be achieved with cake filtration of floc was established with the definition of cake. The expression operation of which the purpose is to reduce the water content of pre-formed filter cake is calculated with our 'unified theory on solid-liquid separation' and compared with the experimental results. The importance of expression is analyzed by the calculated whole procedure of cake filtration and expression. The method determining the most effective operational conditions of filter press including the cake discharge and washing time is proposed.

The Effect of Coagulant on Filtration Performance in Submerged MBR System (침지형 MBR 공정에서 응집제가 여과성능에 미치는 영향)

  • Kim Kwan-Yeop;Kim Ji-Hoon;Kim Young-Hoon;Kim Hyung-Soo
    • Membrane Journal
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    • v.16 no.3
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    • pp.182-187
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    • 2006
  • The purpose of this study was to investigate effect of coagulation on filtration performance of membrane in submerged MBR system and influence of continuous aeration to reduce fouling of membrane surface on coagulated floc. For this purpose, aeration tank sludge of MBR system was compared with jar-test sludge. The experimental results were analysed in terms of floc size and SRF (Specific resistance of Filtration). The more alum was added, the more content of floc below $10{\mu}m$ reduced and SRF decreased. But compared with jar-test results, it was found that effect of coagulation on MBR floc was reduced. Operation time of membrane in alum added MBR was longer than that in control MBR. But operation time was not proportional to alum dose. It was thought that the result was reason that floc below $10{\mu}m$ was not reduced sufficiently by shear force of continuous aeration. Moreover it was founded that if alum is added more than proper dose, it brings filtration resistance to increase.

Evaluation of High Flux Combined with Pretreatment Process for Application of Decentralized Water Supply System with Ceramic Membrane (세라믹 분리막의 분산형 용수공급 시스템 적용을 위한 전처리 연계공정의 고플럭스 평가)

  • Kang, Joon-Seok;Park, Seo Gyeong;Lee, Jeong Eun;Kang, So Yeon;Lee, Jeong Jun;Quyen, Vo Thi Kim;Kim, Seongsu;Kim, Han-Seung
    • Journal of Korean Society of Water Science and Technology
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    • v.26 no.6
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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.

Effect of coagulation conditions on ultrafiltration for wastewater effluent

  • Maeng, Sung Kyu;Timmes, Thomas C.;Kim, Hyun-Chul
    • Membrane and Water Treatment
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    • v.8 no.2
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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.

Study on the Theoretical and Experimental Application of Filtration-Permeation Method (여과-투과 방법의 이론적, 실험적 응용에 대한 연구)

  • Song, Yun-Min;Yim, Sung-Sam
    • Journal of Korean Society of Environmental Engineers
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    • v.30 no.2
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    • pp.161-167
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    • 2008
  • Using an experimental method named filtration-permeation, the influence of sedimentation during filtration was studied for the suspensions composed of particles and that of flocs. The average specific cake resistances measured by filtration do not give accurate values because of the sedimentations during filtration, but the permeation data give quite accurate values. The prolonged permeation rates for the cake formed from particulate suspension do not change, but that rate from the floc filtration changes by the sweeping of flocculant. It is proposed that the cake compressibility can be measured with one set of filtration-permeation experiment by step increase of pressure during permeation period. The another experimental method which can shorten experimental time for floc filtration using filtrationpermeation is also proposed.

The Role of pd in the Unified Theory on Solid-Liquid Separation: Especially on the Cake Thickness at Hindered Sedimentation, Cake Filtration and Expression (고액분리 통합이론에서 pd의 역할: 간섭침전, 케이크 여과, 압착에서 케이크 두께를 중심으로)

  • Yim, Sung-Sam;Song, Yun-Min
    • Korean Chemical Engineering Research
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    • v.50 no.2
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    • pp.334-342
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    • 2012
  • To know the role of 'the solid compressive pressure to the first solid layer of a cake, $p_d$' in the 'unified theory on solid-liquid separation', we analyzed extremely compressible cake formed with floc for the following three operations with our new concepts. First, the role of $p_d$ was studied in calculating the sediment thickness of floc, and in calculating the cake thickness in cake filtration performed with floc sediment. Second, we calculated the expression procedure using $p_d$. Finally, the influence of $p_d$ on cake thickness in hindered sedimentation, and on the calculation of the procedure of hindered sedimentation $p_d$ was verified. Thus the possibility of application of 'unified theory on solid-liquid separation' and the importance of $p_d$ was verified. Through these processes, new theoretical definitions of the cake filtration, expression and hindered sedimentation was established.

Study of a hybrid process combining ozonation and ceramic membrane for drinking water treatment (I) : manganese removal (정수처리를 위한 전오존-세라믹 막여과 조합공정에 관한 연구(I) : 망간 제거 중심)

  • Jin, Kwang Ho;Lim, Jae Lim;Lee, Kyung Hyuk;Wang, Chang Gun
    • Journal of Korean Society of Water and Wastewater
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    • v.22 no.6
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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.

Characteristics of Stock Drainage Depending on Refining Load and Analysis of Drainage Factors (고해하중변화에 의한 탈수성과 탈수영향 인자 분석)

  • 장현성;박종문
    • Journal of Korea Technical Association of The Pulp and Paper Industry
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    • v.36 no.2
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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 $5.6 kg_f$.

Effect of cake resistance by first-aggregation of in-line injection system (인라인 주입방식의 최초응집이 케이크 저항에 미치는 영향)

  • KIM, Taeyoung;PARK, Heekyung
    • Journal of Korean Society of Water and Wastewater
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    • v.22 no.3
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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.

Effects of Characteristics of Flocculent Aggregates on Membrane Fouling in Microfiltration with Coagulation Pretreatment (전처리로 응집공정을 이용한 정밀여과 공정에서 응집 플록 특성에 따른 막오염 연구)

  • Lee, Seockheon;Kweon, Ji Hyang;Choi, Yang Hun;Ahn, Kyu-Hong
    • Journal of Korean Society of Water and Wastewater
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    • v.18 no.6
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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.