• Title/Summary/Keyword: Filtration Resistance

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Filtration Performance in MSBR (Membrane-Coupled Sequencing Batch Reactor) using a Membrane for Both Filtration and Aeration (막결합형 연속회분식 생물반응조에서 여과 및 공기공급용으로 분리막을 사용할 때 공기공급이 막여과 성능에 미치는 영향)

  • Ryu, Kwan-Young;Park, Pyung-Kyu;Lee, Chung-Hak
    • Journal of Korean Society on Water Environment
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    • v.21 no.4
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    • pp.337-346
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    • 2005
  • An MSBR using a membrane for not only filtration but also aeration (MA-MSBR) was designed to reduce membrane fouling and to enhance water quality, and compared with an MSBR using a membrane for only filtration (BA-MSBR). COD removal efficiency of the MA-MSBR was similar to that of the BA-MSBR, but membrane performance of the MA-MSBR was better than that of the BA-MSBR. The MA-MSBR had more small particles in mixed liquor, so the specific cake resistance of flocs in the MA-MSBR was higher than that in the BA-MSBR. However, in the aerobic reaction step of the MA-MSBR, air went through membrane pores and out of the membrane surface, so cake layers on the membrane surface and a portion of organics adsorbed on membrane pores could be removed periodically. Therefore, cake resistance, $R_c$, and fouling resistance by adsorption and blocking, $R_f$, for the MA-MSBR increased more slowly than those for the BA-MSBR. Additionally, in order to compare the energy efficiency for two MSBRs, oxygen transfer efficiency and power to supply air into the reactor by a membrane module and a bubble stone diffuser were measured using deionized water. From these measurements, the transferred oxygen amount per unit energy was calculated, resulting that of MA-MSBR was slightly higher than that of BA-MSBR.

Comparison of Filtration Resistances according to Membrane Cleaning Methods (막표면의 케이크층 세정 방법에 따른 여과 저항값 비교)

  • Han, Song-Hee;Chang, In-Soung
    • Journal of Environmental Science International
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    • v.25 no.6
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    • pp.817-827
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    • 2016
  • The resistance in series model has been frequently used for determination of various filtration resistance to correctly understand the membrane fouling behaviour in MBR (membrane bio-reactor) for wastewater treatment. The cake layer resistance ($R_c$) which is commonly determined by calculation of flux dataset that are obtained empirically before and after removing the cake layer on membrane surface. However, the calculated Rc values are very dependent on the cleaning methods adapted for removal of cake layer. This study investigated how the various cleaning options affect $R_c$. Seven different cleaning methods were employed: i) ultrasonication (100 W, 10 min), ii) ultrasonication (200 W, 60 min), iii) ultrasonication (400 W, 120 min), iv) water rinsing in a shaker (100 rpm, 10 min), v) water rinsing in a shaker (300 rpm, 60 min), vi) water rinsing, vii) sponge scrubbing. For the hydrophilic PES membrane, the cake layer removal efficiencies ranged from 64% to 10%, indicating that the removal of cake layer was highly dependent on the cleaning options. For the hydrophobic PVDF membrane, the cake layer removal efficiencies ranged from 79% to 97%. Consequently, a standardized method for cake layer removal to determine cake resistance ($R_c$) is needed for correct interpretation of the fouling phenomena.

Fouling characteristics of humic substances on tight polysulfone-based ultrafiltration membrane

  • Ariono, Danu;Aryanti, Putu T.P.;Wardani, Anita K.;Wenten, I.G.
    • Membrane and Water Treatment
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    • v.9 no.5
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    • pp.353-361
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    • 2018
  • Fouling characteristics of humic substances on tight ultrafiltration (UF) membrane have been investigated. The tight UF membrane was prepared by blending polysulfone (PSf) in N.N-dimethylacetamide (DMAc) with 25%wt of Polyethylene glycol (PEG400) and 4%wt of acetone. Fouling characteristic of the modified PSf membrane was observed during peat water filtration in different trans-membrane pressure (TMP). It was found that the acetone modified membrane provided 13% increase in TMP during five hours of peat water filtration, where a stable flux was reached within 150 minutes. Meanwhile, the increase of TMP from 10 psig to 30 psig resulted in a fouling resistance enhancement of 60%. Furthermore, based on the fouling analysis, fouling mechanism at the first phase of filtration was attributed to intermediate blocking while the second phase was cake formation.

Dewatering Characteristic of Water Treatment Plant Sludges based on Detention Time (체류시간에 따른 정수장슬러지의 탈수특성)

  • Moon, Yong-taik;Kim, Byung-goon;Kim, Youn-kwon;Kim, Hong-suck
    • Journal of Korean Society of Water and Wastewater
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    • v.21 no.6
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    • pp.709-715
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    • 2007
  • The dewaterability of a sludge can be characterized by two ways: the residual moisture content in the sludge cake after dewatering process, and the filtration of the sludge. Time to filter (TTF) represents filtration processes that are special cases of the flow through a solid matrix concept. TTF characterizes a resistance to filtration. The sludge resistance, in turn, can be subdivided into resistances associated with the solid phase and the liquid phase to evaluate the effect of each of the two phases on sludge dewaterability. In order to determine the dewatering characteristics of the water sludge samples, TTF and zeta potential were measured. For these studies cationic polymer was chosen for water sludge dewatering experiments. The zeta potential of thickener sludges neared from minus values to zero values till 4 days after sampling. The dewaterability of thickener sludges using cationic polymer was deteriorated according to the increase of detention time. As the detention time was increased from 4 to 10 days, the optimal dose of the polymer was increased from 4 to 8mg/L. Therefore, the optimal detention time plays an important part for the dewaterability of a sludge.

Micro-Filtration Performance of Metal Membrane md Fouling Reduction by Intermittent Ozonation (금속 막의 정밀 여과 특성 및 간헐적 오존 처리에 의한 막 오염 저감)

  • 김종오;정종태
    • Membrane Journal
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    • v.14 no.1
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    • pp.66-74
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    • 2004
  • Total resistance of membrane in a micro-filtration system using a metal membrane was mainly attributed to the permeate resistance of cake layer($R_c$), which was formed by deposited particles from the physico-chemical interactions of solids on membrane surface. Intermittent back ozonation was highly effective than the air backwashing for fouling reduction. As far the operational effect, under same ozone injection, the increase of gas flow-rate was more favorable than the increase of injection time far the recovery of permeation flux. As the filtration time was longer, the effect of flux recovery by intermittent back-ozonation decreased. Therefore, it is preferable to operate membrane cleaning before the foulant is consolidated on membrane surface.

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 Particulate Matter Filtration Characteristics of the Metal Foam Particulate Filter (메탈 폼 입자 필터의 GDI 엔진 입자상 물질 정화 특성에 대한 연구)

  • Jang, Wonwook;Myung, Cha-Lee;Lee, Jeongmion;Park, Simsoo
    • 한국연소학회:학술대회논문집
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    • 2014.11a
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    • pp.347-348
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    • 2014
  • After-treatment system for gasoline direct injection engines should be considered due to the regulation standard for particle number emitted from spark ignition engine vehicles. A metal foam particulate filter, which is thought to be more proper for gasoline engines for its unique filtration and heat resistance characteristics, has been evaluated via engine dynamometer tests.

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A study on possibility of using CST as a fouling evaluation index at MBR (MBR에서 fouling 평가지표로서 CST의 활용 가능성에 대한 연구)

  • Kim, Yun-Ji;Choi, Yun-Jeong;Sim, Tae-Suk;Hwang, Sun-Jin
    • Journal of Korean Society of Water and Wastewater
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    • v.35 no.6
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    • pp.379-387
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    • 2021
  • In general, trans-membrane pressure (TMP), flux, filtration resistance are used as indicators to evaluate the degree of fouling in MBR. However, they have limitations in determining the level of EPS generation, which is known as an important factor of fouling. Therefore, a new evaluation method is required to monitor the amount of EPS generation. In this study, the applicability of capillary suction time (CST), which is used to measure the dewaterability of sludge, was evaluated as an indirect fouling evaluation index. Statistical analysis was performed to evaluate the effect of EPS on CST, and to determine whether EPS has high similarity with representative fouling evaluation indicators and CST, and quantitatively compared them. As a result, the correlation coefficient between CST and bEPS was 0.7988, which was higher than the correlation coefficient between filtration resistance and bEPS. Since bEPS is a major factor inducing fouling by affecting the formation of the cake layer, it was evaluated that CST, which has a high correlation with bEPS, is suitable to represent EPS. In addition, it was evaluated that the correlation coefficient between filtration resistance and CST was high as 0.7187, which could be used as a fouling evaluation index.

Comparison study on membrane fouling by various sludge fractions with long solid retention time in membrane bioreactor

  • Sun, Darren Delai;Liu, Shushu
    • Membrane and Water Treatment
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    • v.4 no.3
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    • pp.175-189
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    • 2013
  • A membrane bioreactor (MBR) with sludge retention time (SRT) of 300 days was maintained for over 2 years. Polypropylene microfiltration (MF) membrane with pore size of 0.2 ${\mu}m$ was used in the MBR system. The fouling behaviors of various sludge fractions from the MBR were studied and sub-divided resistances were analyzed. It was observed that $R_{cp}$ was a dominant resistance during the filtration of activated sludge, contributing 63.0% and 59.6% to the total resistance for MBR and sequential batch reactor (SBR) respectively. On the other hand, $R_c$ played the significant role during the filtration of supernatant and solutes, varying between 54.54% and 67.18%. Compared with $R_{cp}$ and $R_c$, $R_{if}$ was negligible, and $R_m$ values remained constant at $0.20{\times}10^{12}m^{-1}$. Furthermore, resistances of all sludge fractions increased linearly with rising mixed liquor suspended solids (MLSS) concentration and growing trans-membrane pressure (TMP), while the relationship was inversed between fraction resistances and cross flow velocity (CFV). Among all fractions of activated sludge, suspended solid was the main contributor to the total resistance. A compact cake layer was clearly observed according to the field emission scanning electro microscopy (FE-SEM) images.

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.