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Advanced Membrane TechnologiesStanford University, May 07, 2008Advanced Membrane TechnologiesStanford University, May 07, 2008

Ingo Pinnau, Ph.D.

Mem branes for Wat er Treat m ent :

Proper t ies and Charac t er izat ion

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Membrane SeparationProcesses and CharacteristicsMembrane SeparationProcesses and Characteristics

Molecular(Nonporous)< 10Solution/DiffusionReverseOsmosis (RO)

Mesopores20 - 500Size ExclusionUltrafiltration(UF)

Macropores500 - 50,000Size ExclusionMicrofiltration(MF)

Macropores> 50,000Size ExclusionParticleFiltration

TransportRegimePore Size()SeparationMechanismProcess

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Membrane SeparationProcesses and CharacteristicsMembrane SeparationProcesses and Characteristics

0.001 0.01 0.1 1.0 10 100 1,000

Beach sand

Granular

activatedcarbon

Human hair

Yeast cells

Bacteria

Paint pigment

Oil emulsion

Albuminprotein

Endotoxin/Pyrogen

Colloidalsilica

Asbestos

Pesticides/Herbicides

Aqueoussalts

Viruses

Metal

ions

0.0001(m)

Sugars

Reverse Osmosis

Nanofiltration

Ultrafiltration

Microfiltration

Particle Filtration

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Membrane Characteristics:Porous MembranesMembrane Characteristics:Porous Membranes

MonovalentMonovalentionsions MultivalentMultivalentionsions SuspendedSuspendedsolidssolidsWaterWater VirusesViruses BacteriaBacteria

MicrofiltrationMicrofiltration

MonovalentMonovalentionsions

MultivalentMultivalentionsions

SuspendedSuspendedsolidssolidsWaterWater VirusesViruses BacteriaBacteria

UltrafiltrationUltrafiltration

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Membrane Characteristics:Non-Porous MembranesMembrane Characteristics:Non-Porous Membranes

MonovalentMonovalent

ionsions MultivalentMultivalentionsions SuspendedSuspendedsolidssolidsWaterWater VirusesViruses BacteriaBacteria

NanofiltrationNanofiltration

MonovalentMonovalentionsions

MultivalentMultivalentionsions

SuspendedSuspendedsolidssolidsWaterWater VirusesViruses BacteriaBacteria

ReverseReverseOsmosisOsmosis

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Ideal Membranes for UF, NF andRO ApplicationsIdeal Membranes for UF, NF andRO Applications

High water flux (low capital cost) High solute rejection (high water purity) Long-term stability of water flux and rejection

(Membrane fouling)

Mechanical, chemical and thermal stability Minimum pre-treatment (backflushing and chemicaltreatment)

Can be processed into large-scale membranes and

modules Inexpensive!

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Problems of Current MembranesUsed in UF and RO ApplicationsProblems of Current MembranesUsed in UF and RO Applications

Poor long-term stability of water flux(Membrane Fouling)

Backflushing and chemical treatment

High membrane replacement cost

Poor resistance to chlorine

Membrane system size

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Major Foulant Types in Natural andIndustrial WastewaterMajor Foulant Types in Natural andIndustrial Wastewater

ScalingScaling

ColloidalColloidalFoulingFouling

BiofoulingBiofouling

OrganicOrganicFoulingFouling

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Surface Structure of a TypicalUF MembraneSurface Structure of a TypicalSurface Structure of a TypicalUF MembraneUF Membrane

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Membrane SeparationProcesses and CharacteristicsMembrane SeparationProcesses and Characteristics

Porous SurfacePorous Surface

UnfouledUnfouled MembraneMembrane Fouled Membrane

Surface Fouling

Internal Fouling

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Schematic Structures of Porousand Non-Porous UF MembranesSchematic Structures of PorousSchematic Structures of Porousand Nonand Non--Porous UF MembranesPorous UF Membranes

Microporous Ultrafiltration Membrane

Selective skin layerSelective skin layer

Porous substratePorous substrate

Non-Porous Ultrafiltration Membrane

NonNon--porous hydrophilicporous hydrophilicSurface coating (0.1Surface coating (0.1--0.50.5 m)m)

Porous substratePorous substrate

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Cross-Section of a Non-PorousUF MembraneCross-Section of a Non-PorousUF Membrane

Nonporous PolymerNonporous PolymerCoating LayerCoating Layer(~ 0.3(~ 0.3 m)m)

MicroporousMicroporousSupport MembraneSupport Membrane

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Long-Term Water Flux of Porous andNon-Porous Ultrafiltration MembranesLong-Term Water Flux of Porous andNon-Porous Ultrafiltration Membranes

10

100

1,000

0 5 10 15 20 25 30 35

Water flux(L/m2h)

Permeation Time (Days)

MicroporousPVDF module

Non-porousPebax 1074/PVDF

module

water flushwater flush

pure waterFeed: 1% motor oil in waterFeed pressure: 150 psigFeed temperature: 23C

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Fouling Index of Porous and Non-

Porous Ultrafiltration Membranes forSeparation of Oil/Water Emulsions

Fouling Index of Porous and Non-

Porous Ultrafiltration Membranes forSeparation of Oil/Water Emulsions

0.01

0.1

1

0 5 10 15 20 25 30 35

ouling IndexH2O(t)/JH2O(0)

Permeation Time (Days)

MicroporousPVDF module

Pebax 1074 module

pure water

water flushwater flush

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Long-Term Permeation Properties of

Porous Ceramic and Ceramic/PolymerComposite Membranes

Long-Term Permeation Properties of

Porous Ceramic and Ceramic/PolymerComposite Membranes

0

0.5

1

1.5

2

2.5

0 20 40 60 80 100 120

PermeationResistance

(psi/gfd)

Time (hours)

Backflush

CeramicModule

Ceramic/Pebax 1074Module

Feed: Bilge water ; permeate flux: 40 gfd

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Membrane Types Used in

Ultrafiltration, Nanofiltration andReverse Osmosis

Membrane Types Used in

Ultrafiltration, Nanofiltration andReverse Osmosis

Integral asymmetric membrane (Cellulose acetate)Integral asymmetric membrane (Cellulose acetate)Selective layer (Material A)

Microporous substrate(Material A)

ThinThin--film composite membrane (Polyamide)film composite membrane (Polyamide)

Selective layer (Material A)

Microporous substrate(Material B)

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2003 RO/NF Membrane Sales2003 RO/NF Membrane Sales

44

4

58

11

30

34Share (%)

15Others12TriSep

15Toyobo

18Koch/Fluid Systems

27GE Osmonics

36Toray

99Nitto Denko/Hydranautics

115Dow/FilmtechSales ($ MM)Company

R. Truby, Water Executive, September/October 2004, p.11(Supplement of Ultrapure Water 21, 2004)

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4Plate-and-frame

5Cellulose acetate hollow fiber

module

91Polyamide spiral-wound(8x40)

Market Share (%)Module Type

Expected RO/NF membrane lifetime ~ 3Expected RO/NF membrane lifetime ~ 3--5 years.5 years. Actual RO/NF membrane lifetime ~ 7Actual RO/NF membrane lifetime ~ 7--12 years.12 years. Membrane replacement makes up for ~ 60% of annual sales.Membrane replacement makes up for ~ 60% of annual sales.

R. Truby, Water Executive, September/October 2004, p.9(Supplement of Ultrapure Water 21, 2004)

2003 RO/NF Module Sales Distribution

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Incremental Changes in Spiral-Wound RO Module PerformanceIncremental Changes in Spiral-Wound RO Module Performance

Dave Furukawa (1999)

99.37.041.940.141999

30.83.521.660.191995

7.92.011.320.341990

2.61.561.100.651985

1.01.001.001.001980

Figure ofMerit

Reciprocal Salt Passage(Normalized to 1980)

Productivity(Normalized to 1980)

Cost (Normalized to 1980U.S.$)

Year

Figure of Merit = (Productivity) x (1/Salt Passage)Cost

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Interfacial Polymerization for Preparationof Thin-Film Composite RO Membranes

Interfacial Polymerization for Preparation

of Thin-Film Composite RO Membranes

Hydrocarbon/acid chloridesolution

Polyamide layer

~ 0.1-0.2 m

Aqueousaminesolution

Porous

support

Heat cure

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Formation of FT 30 Thin-FilmComposite MembraneFormation of FT 30 Thin-FilmComposite Membrane

NH2

NH2

ClOC

COCl

COCl

NH NHCO CO

CO

HN NHCO CO

COOH

n 1- n

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Formation of PEC 1000 Thin-FilmComposite MembraneFormation of PEC 1000 Thin-FilmComposite Membrane

N N

NO

O

O

HOH2CH2C

CH2CH2OH

CH2CH2OHO

CH2OHH2SO4

OCH2CH2

N N

NO

O

O

CH2CH2

CH2CH2OCH2CH2CH2

N

N NCH2

O

HO3S

CH2 CH2CH2O

O

O

O

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Rejection and Water Flux of ROSeawater Desalination MembranesRejection and Water Flux of ROSeawater Desalination Membranes

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Organic Solute Rejection ofCommercial RO MembranesOrganic Solute Rejection ofCommercial RO Membranes

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Surface Structures of Interfacial

Aromatic Polyamide CompositeMembranes

Surface Structures of Interfacial

Aromatic Polyamide CompositeMembranes

28 gfd 28 gfd

37 gfd 45 gfd

S.-Y. Kwak, D.W. Ihm, J. Membrane Sci. 158 (1999) 143-153

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Cross-Section of Interfacial PolyamideComposite Membranes (BW 30)

Cross-Section of Interfacial Polyamide

Composite Membranes (BW 30)

Ridge and valleyRidge and valleystructurestructure~ 0.2~ 0.2 -- 0.50.5 mm

Selective layerSelective layer~ 500~ 500 -- 1,0001,000

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Surface Structure of Uncoated andCoated RO MembranesSurface Structure of Uncoated andCoated RO Membranes

Uncoated Coated

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Surface Structure of Uncoated andCoated RO Membranes (AFM)Surface Structure of Uncoated andCoated RO Membranes (AFM)

ESPA-3

ESPA-3 - coated

AFM pictures courtesy of Jennifer Louie, Stanford University

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Performance of Commercial and

Modified RO Membranes forWastewater Treatment

Performance of Commercial and

Modified RO Membranes forWastewater Treatment

0

10

20

30

40

50

0 5 10 15 20 25 30

Water Flux(L/m2h)

Permeation Time (Days)

SWC-2

SWC-2/Pebax 4011

Feed: 900 ppm mineral oil; 100 surfactant DC 193Pressure: 500 psigTemperature: 25C

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AcknowledgementsAcknoAcknowledgements

Financial support was provided byOffice of Naval Research and SERDP

Special thanks to my colleagues Isabelle Ciobanu, Sylvie Thomasand Alvin Ng.