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DOW™Water and Process Solutions

Basic Ultrafiltration

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Scale of Filtration ProcessesRemoval capabilities of common filtration processes

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Rejected• Suspended solids

• High molecular weight solutes

• Colloids

• Macromolecules

• Bacteria & coliforms (6-log)

• Virus (2.5-log)

Typical treated water results:

• Turbidity < 0.3 NTU

• SDI < 3

Not Rejected (Passed)• Water

• Low MW dissolved solids

• Salts

• Sugars

• Dissolved organics*

• True colour

• Taste & odor compounds

* Can be removed with coagulationpre-treatment

Removal Capabilities of UF Membranes

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Feed Water Parameters for Design

Minimum feed water quality data:

• Operating temperatures (min/max/avg)

• Turbidity & TSS

• TOC or COD

• Dissolved/total Fe and Mn

• FOG

• pH

Other information:

• Plant capacity (seasonal requirements)

• Feed water source

• End-use (RO pre-treatment, potable water...)

• Seasonal variations (algae blooms, extent/duration of excursions)

• Treated water quality requirements

• Redundancy requirements

Ideally a complete water analysis!!

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DOW™ UF Module

• 0.03µm nominal pore size

• H-PVDF material

• Hollow fibre configuration

• Outside-in flow path

• Pressurized module

• Dead-end filtration (typical)

• Range of active areas available

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Membrane Material Selection

Important properties for a separation membrane are:

1. Selectivity (pore size);

2. Permeability;

3. Strength & flexibility; and

4. Chemical & thermal stability.

Reversal of fouling is the main concern in

low pressure membrane applications!

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DOW™ UF Module

• 0.03µm nominal pore size

• H-PVDF material

• Hollow fibre configuration

• Outside-in flow path

• Pressurized module

• Dead-end filtration (typical)

• Range of active areas available

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• PVDF & PS/PES havesimilar strength

• PVDF is more flexible

– Required for aggressive airscour for more effectivecleaning

– Air scour enhances masstransfer & particulateremoval

5000ppm NaOCl

• PVDF has ~10x greater resistanceto NaOCl

– Better cleanability to restore TMP

– Extended membrane life

• PS/PES membranes usuallylimited to 200 ppm NaOCl

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DOW H-PVDF Material

Hydrophilicmembrane

Lower contactangle for higher

wettability

Higher resistance tofouling

Lower operating pressurerequirements

Source: inno-x.ch

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DOW™ UF Module

• 0.03µm nominal pore size

• H-PVDF material

• Hollow fibre configuration

• Outside-in flow path

• Pressurized module

• Dead-end filtration (typical)

• Range of active areas available

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Anatomy of a Hollow Fibre

Advantages:

• Maximizes fibre area andminimizes footprint

• Can plug a broken fibre tomaintain module integrity

HollowHollow fibrefibrecross sectioncross section

SupportSupportstructurestructure SkinSkin

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DOW™ UF Module

• 0.03µm nominal pore size

• H-PVDF material

• Hollow fibre configuration

• Outside-in flow path

• Pressurized module

• Dead-end filtration (typical)

• Range of active areas available

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Outside-In Advantage

• PVDF material (usually)

• Higher solids tolerance

• More surface area (~2x)

• Higher recovery with air scourassisted backwash

Outside-in

• PS/PES material (usually)

• Risk of plugging fibre lumen

• Fouls more rapidly

• Irreversible fouling ondifficult water

Inside-out

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DOW™ UF Module

• 0.03µm nominal pore size

• H-PVDF material

• Hollow fibre configuration

• Outside-in flow path

• Pressurized module

• Dead-end filtration (typical)

• Range of active areas available

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Pressurized UF• Higher packing density

Smaller footprint

Fewer modules

Less chemicals

• No excavation required

Reduced civil works

Submerged UF• Operates at lower fluxes

More modules required

• TMP limited to < 0.9 bar

Reduced throughput at lowertemperatures

Pressure Driven Advantage

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Module Structure

Filtrate

Feed

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DOW™ UF Module

• 0.03µm nominal pore size

• H-PVDF material

• Hollow fibre configuration

• Outside-in flow path

• Pressurized module

• Dead-end filtration (typical)

• Range of active areas available

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Flow Configuration

Dead-end

• Feed flow is perpendicular to thesurface of the membrane

• Solids and a small percentage of thefeed are retained

• High recovery/low energy

• Batch process

Cross-flow

• Flow travels tangentially across thesurface of the membrane

• A percentage of concentrate isrecirculated

• High energy/low per-pass recovery

• Continuous process

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ConcentrateTo Drain or

Recycle

Concentrate Bleed Format

Filtrate

RawWater

Filter100-300 m

BackwashTank

Air

Chemicals

Backwash Pump

Feed Pump

Waste

(Partially Open)

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DOW™ UF Module

• 0.03µm nominal pore size

• H-PVDF material

• Hollow fibre configuration

• Outside-in flow path

• Pressurized module

• Dead-end filtration (typical)

• Range of active areas available

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DOW™ UF – Product Specs

Product NameSFP, SFD-

2880SFP, SFD-

2860IW102-1100DW102-1100

IW74-1100DW74-1100

Active Area (m2) 77 51 102.5 74

Max Feed Pressure @ 20℃ (Bar) 6.25 5.0

Length (mm) 2360 1860 2359 1780

Empty / Shipping / Flooded Weight(kg) 61 / 71 / 100 48 / 55 / 83 60/70/93 49/56/76

Fibers Materials H-PVDF

Fiber Nominal Pore Size 30 nm

Flow Configuration Out/In

Feed Port 2” Side, Coupling

Filtrate Port 2” Side, Coupling 2” Top, Coupling

Concentrate Port 2” Top, Coupling 2” Side, Coupling

Air Scour ConnectionG 3/8” (Standard) or DN32

Glued Fitting (Option)Bottom

G 3/8” (Standard) or 1 ½”NPT (Option) Side