• Title/Summary/Keyword: Microfiltration

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Preparation and Characterization of Microfiltration Membranes for Water Treatment (수처리용 정밀여과 멤브레인의 제조 및 특성 연구)

  • Jung, Boram;Kim, Nowon
    • Membrane Journal
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    • v.24 no.1
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    • pp.50-62
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    • 2014
  • An asymmetric microfiltration membranes were prepared with polysulfone by an immersion precipitation phase inversion method. Microfiltration membranes were prepared by polysulfone/N-methyl-2-pyrrolidone/polyvinylpyrrolidone/phosphoric acid casting solution and water coagulant. The vapor induced phase inversion method was used to prepare the membranes. The pore size and the morphology were changed by the phosphoric acid additive, the temperature of casting plate and the exposure time at the relative humidity of 74%. The morphology of membranes was investigated by scanning electron microscopy and microflow permporometer. By the addition of the phosphoric acid additive in the casting solution, the morphology of the prepared membranes were changed from a dense sponge structure to a loose asymmetric sponge structure. Due to the addition of catalytic amount of phosphoric acid to NMP casting solution, the mean pore size increased almost $0.2{\mu}m$ and the water flux increased about 3,000 LMH. The temperature of casting plate and exposure time had a apparent effect on the skin layer structure and the pore size and the porosity of the membrane.

Water Treatment of High Turbid Source by Tubular Ceramic Microfiltration with Periodic Water-back-flushing System

  • Lee, Hyuk-Chan;Park, Jin-Yong
    • Korean Membrane Journal
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    • v.9 no.1
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    • pp.12-17
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    • 2007
  • We performed periodic water-back-flushing using permeate water to minimize membrane fouling to enhance permeate flux in tubular ceramic microfiltration system for water treatment of high turbid source. The filtration time (FT) = 2 min with periodic 6 sec water-back-flushing showed the highest value of dimensionless permeate flux ($J/J_o$), and the lowest value of resistance of membrane fouling ($R_f$), and we acquired the highest total permeate volume $(V_T)\;=\;6.805L$. Also in the result of BT effect at fixed FT = 10 min and BT (back-flushing time) = 20 sec showed the lowest value of $R_f$ and the highest value of $J/J_o$, and we could obtain the highest $V_T\;=\;6.660\;L$. Consequently, FT = 2 min and BT = 6 sec could be the optimal condition in water treatment of high turbid source above 10 NTU. However, FT = 10 min and BT = 20 sec was superior to reduce operating costs because of lower back-flushing frequency. Then the average quality of water treated by our tubular ceramic MF system was turbidity of 0.07 NTU, $COD_{Mn}$ of 1.86 mg/L and $NH_3-N$ of 0.007 mg/L.

Fluoride removal using Alum & PACl in batch & continuous mode with subsequent microfiltration

  • Dubey, Swati;Agarwal, Madhu;Gupta, A.B.
    • Membrane and Water Treatment
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    • v.12 no.2
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    • pp.83-93
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    • 2021
  • In this study, defluoridation efficiency by aluminium sulphate (alum) and polyaluminium chloride (PACl) were compared for recommended Nalgonda dose (100%) and 80% of this dose in both batch and continuous modes. The residual turbidity was found to be higher in case of alum as compared to PACl with 80% dose representing lesser efficient settling of suspensions, which primarily comprise alumino-fluoro complexes that result in high residual aluminium in the treated water and this was confirmed by TEM and Zeta analysis. Moreover, the application of PACl also resulted in much lesser addition to the TDS and also required lesser lime for pH compensation due to its lower acidity. Hence this reduced dose was recommended for defluoridation. It was also observed that in case of alum, residual aluminium in treated water was 0.88 mg/L (100% dose) & 0.72 mg/L (80% dose) and in case of PACl, it was 0.52 mg/L(100% dose) & 0.41 mg/L(80% dose). After subsequent microfiltration, residual aluminium was 0.28 & 0.21 mg/L for 100% & 80% dose respectively and in case of alum and in case of PACl, it was 0.16 & 0.11 for 100% & 80% dose respectively, which conform to the Al standards(<0.2 mg/L).

The Degumming and Sericin Recovery of the Silk fabric Using the Electrolytic Water(II) (전해수를 이용한 견섬유 정련 및 세리신 회수(II)-분리막에 의한 세리신 농축을 중심으로-)

  • 배기서;이태상;노덕길;홍영기
    • Textile Coloration and Finishing
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    • v.16 no.4
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    • pp.10-18
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    • 2004
  • In this work, Aqueous sericin solution was prepared by degumming process with electrolytic reduction water. Then, the microfiltration and ultrafiltration systems were applied to the concentration of aqueous sericin solution. The objective of this study was to select the optimum operating condition among the different pressure. The permeate flux and rejection ratio were observed with time, pressure, flow rate and concentration. and, the wastewater and permeated water quality values such as pH, BOD, COD, and NH levels were measured. In order to see the influence of electrolytic reduction water, the flux of pure water and electrolytic reduction water by PVDF22(MF) and PS100(UF) membrane was measured. In microfiltration system, the relative flux reduction decreased rapidly to 0.02 in the 30min, as the concentration polarization and gel layer formation were increased. and then the sericin concentration rejection ratio was 40%. In ultrafiltration system, the permeate flux decreased with time and concentration, and increased with the operating pressure and flow rate. Optimal condition in PS100 membrane system for sericin concentration was operating pressure 1.464kgf/$cm^24, operating flow rate $7\ell/min at\; 40^{\circ}C$. At that time, sericin concentration rejection ratio was 83% respectably. The sericin solution was concentrated from 0.1wt% solution to 0.2 wt % solution during about 2 hrs by the UF filteration membrane system.

Long Term Operation of Microfiltration as a Pretreatment for Seawater Reverse Osmosis Processes (정밀여과를 이용한 역삼투법 해수담수화 전처리 공정의 장기운전 특성)

  • Kim, Su-Han;Kim, Chung-H.;Kang, Suk-H.;Lim, Jae-L.
    • Journal of Korean Society of Water and Wastewater
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    • v.24 no.6
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    • pp.735-741
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    • 2010
  • A pilot test was carried out to investigate the long term operation characteristics of Microfiltration (MF) system as a pretreatment for seawater reverse osmosis (SWRO) processes for two years. A commercialized MF module with pressurized operation type was used to filter seawater to remove particles which can foul reverse osmosis (RO) membrane. Silt Density Index (SDI) values of filtered seawater by the MF system were ranged from 0.14 to 1.79, which meet the SDI standard for RO feed water as depicted in previous literatures. Although the tested seawater is quite clean (i.e., dissolved organic cabon (DOC) concentration and turbidity were about 1 mg/l and less than 1 NTU, respectively) enough not to foul the MF membrane, steep increase in trans-membrane pressure (TMP) with a constant flux were observed over a whole operation period. A set of operation and water analysis data implies that the steep increase in TMP was resulted from iron and maganese fouling by the combination of metal corrosion by seawater and oxidation state by aeration and residual chlorine.

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.

Cake Reduction Mechanism in Coagulation-Crossflow Microfiltration Process (Crossflow 방식 응집-정밀여과 공정의 케이크층 저감 메커니즘)

  • Kim, Suhan;Park, Heekyung
    • Journal of Korean Society of Water and Wastewater
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    • v.17 no.4
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    • pp.519-527
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    • 2003
  • Cake layer in crossflow microfiltration(CFMF) can be reduced by coagulation, enhancing membrane flux. This is because enlarging particle size by coagulation increases shear-induced diffusivity and the back-transport of rejected particles. However it is known that the enlarged particles are disaggregated by the shear force of the pump while passing through it. This study is to look at the disaggregation in relation with cake layer reducation. Kaolin and polysulfon hollow fiber microfilter are used for experiment. The reduction of cake resistance by coagulation is observed in a range of 17% to 53% at the various coagulation conditions. The particle size analysis results of the experiments show that aggregated particles in feed are completely disaggregated by pump but re-aggregation of particles occurs in membrane. This suggestes that the re-aggregation of particles is critical to cake reduction and flux enhancement, since the aggregated particles are completely broken. The mechanisms for re-aggregation in membrane are the same with those for coagulation in feed tank. Charge neutralization is better for CCFMF than sweep flocculation although it has two drawbacks in operation.

Permeation Behavior of Microfiltration Membrane by Alumina Colloidal Suspension under a Cyclic Variation in TMP (운전압력의 순환변화에 따른 알루미나 현탁액의 정밀여과 투과거동)

  • Nam, Suk-Tae;Han, Myeong-Jin
    • Membrane Journal
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    • v.21 no.1
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    • pp.13-21
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    • 2011
  • This study investigated the fouling behavior of $Al_2O_3$ colloids on polyethylene microfiltration membrane. To examine the effect of operation variation on fouling, operating pressure was increased from 0.49 to 1.96 bar along with time elapses and then was reduced to 0.49 bar reversely. A hysteresis behavior was observed in the membrane permeate flux over pressure, revealing different fluxes at the same pressure according to the pressure control type, increasing and decreasing. Permeate resistance and its rate of increase was higher in the decreasing pressure cycle than in the increasing pressure cycle. At the initial period of filtration, fouling mechanism for the both cycles was governed by the cake filtration. The degree of fouling was higher in the decreasing pressure cycle compared with in the increasing pressure cycle.

PVDF-TiO2 coated microfiltration membranes: preparation and characterization

  • Shon, H.K.;Puntsho, S.;Vigneswaran, S.;Kandasamy, J.;Kim, J.B.;Park, H.J.;Kim, I.S.
    • Membrane and Water Treatment
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    • v.1 no.3
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    • pp.193-206
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    • 2010
  • Organic fouling and biofouling pose a significant challenge to the membrane filtration process. Photocatalysis-membrane hybrid system is a novel idea for reducing these membranes fouling however, when $TiO_2 photocatalyst nanoparticles are used in suspension, catalyst recovery is not only imposes an extra step on the process but also significantly contributes to increased membrane resistance and reduced permeate flux. In this study, $TiO_2$ photocatalyst has been immobilized by coating on the microfiltration (MF) membrane surface to minimize organic and microbial fouling. Nano-sized $TiO_2$ was first synthesized by a sol-gel method. The synthesized $TiO_2$ was coated on a Poly Vinyl Difluoride (PVDF) membrane (MF) surface using spray coating and dip coating techniques to obtain hybrid functional composite membrane. The characteristics of the synthesized photocatalyst and a functional composite membrane were studied using numerous instruments in terms of physical, chemical and electrical properties. In comparison to the clean PVDF membrane, the $TiO_2$ coated MF membrane was found more effective in removing methylene blue (20%) and E-coli (99%).

Characteristics of residuals from the 2nd-stage microfiltration in a dual membrane process (침지식 2단 막여과 고도 정수처리 시스템의 최종배출수 특징)

  • Lee, Seung Ryul;Kweon, Ji Hyang;Hur, Hyung Woo;Yeon, Kyeong Ho;Park, Ki Young
    • Journal of Korean Society of Water and Wastewater
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    • v.23 no.1
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    • pp.31-37
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    • 2009
  • Low-pressure membrane processes have been extensively expanded their applications to drinking water production in a few decades. As a capacity of a membrane plant becomes greater in recent years, proper methods to increase water production as well as to treat residuals have drawn great attention. A possible treatment option for the better water production is to apply a dual membrane system. The second stage microfiltration was installed and operated for approximately six months. The residuals from the two stage microfiltration were investigated to learn their characteristics in settling and dewatering processes. The settlability of the membrane residuals were greatest at the SS concentration of approximately 15000mg/L. The proper dose of the polyelectrolytes for filterability were obtained in the range of 0.5~1%. In the dosage range, the water contents of the membrane residuals were greater but the SRF were lower than the residual from the conventional process.