Microfiltration / Reverse Osmosis

The 1-2 Punch for Water Treatment

Presented by:

Don Burgess

DWG Process Supply Ltd.

CLOTH & DEPTH FILTERSR A N G E S O F F I L T R A T I O N P R O C E S S E S

MEMBRANETYPE

RELATIVE SIZEOF COMMON MATERIALS

REVERSEOSMOSIS

NANO-FILTRATION

ULTRAFILTRATION

MICROFILTRATION

SCREENS & STRAINERS

LATEX EMULSIONS

METAL IONS

VIRUSVOC’S, PCD, SUSP. OIL

AQUEOUSSALTS

ATOMICRADII

PROTEINS/ENZYMES

OIL EMULSIONS

PAINT PIGMENT

BACTERIA

HUMANHAIR

SAND

RED BLOODCELLS

CARBONBLACK

DISSOLVED ORGANICS

PARTICLE SIZE 10-4 10-3 10-2 10-1 1.0 10 102 103

(MICRONS)

APPROXIMATE 100 200 20,000 500,000 MOLECULAR WT.

PARTICLE SIZE 1 10 100 1,000 10,000 100,000 106 107

(ANGSTROMS)

Cryptosporidium Oocyst

Giardia Cyst

Material Sizes

Source: GE Water

Filtration Processes

Microfiltration / Ultrafiltration

• Removes turbidity• Provides barrier

to Crypto/Giardia• Backwashable

“Surface Water”

“Spaghetti removes Solids”

Reverse Osmosis / Nanofiltration

• Removes dissolved compounds

• Typically can not backwash

• Fouled by turbidity

“Ground Water”

“Layered removes Liquids”

Microfiltration

Membrane Pore Sizes – 0.01 to 0.2 micron

Pencil Dot (40 µm)

Giardia Cyst (5 - 11 µm)

Large Siliceous Particle (20 µm)

CryptosporidiumOocyst (2 - 5 µm)[Anthrax Spore]

Typical Bacterium (0.2 µm)

E-Coli(.45 µm)

How Small is Small?

Why Microfiltration?

• Turbidity and Microbiology removal with no chemistry– Turbidity < 0.1 NTU

• 0.02 to 0.04 NTU

– Cryptosporidium > 99.9999% Removal

– Giardia > 99.9999% Removal

• TOC / Colour removal– Chemical precipitation– Coagulation with Alum / acid / PAC– Removal of precipitate with membrane

Inlet Section

Source: Pall Canada

Pressure Membranes• MF Fiber = 0.1 micron

• PVDF - Oxidant Resistant (Chlorine, Ozone & Chlorine Dioxide)

• Outside – In

• Rack Mounted Vertically

Source: www.zenonenv.com

Immersed Membranes

• UF Fiber = 0.035 micron

• Composite

• Outside – In

• Vacuum

• Mounted in Below or Above Grade Tanks

Source: Pall Canada

Pressure System (35 MLD - Pall)

Source: www.zenonenv.com

Immersed Wastewater System (Zenon)

Modular System 1.3 to 2.0 MLD

MF Test ResultsSite 1 Site 2 Treated

Water

Raw Water

Turbidity (NTU) 1 to 7 10 to 25 <0.02

TOC (mg/L) 9 to 11 10 to 15 4 to 6

Colour (TCU) 5 to 40 23 to 40 < 5

Chemical Dosages

Alum (mg/L) 100 75 to 100

PAC (mg/L) 10 13

MF Membrane Technology Benefits

• Exceeds Environmental Treatment Standards• Consistent treatment quality• Modular, Compact and Cost Saving System

Configurations• Some Membranes Warranted for 10 Years• Automatic Integrity Testing• On-Line Technical Support and System

Diagnosis

Reverse Osmosis / Nanofiltration

RO / Nano filtration

• Removes dissolved compounds• Non-backwashable • Max 0.5 to 1 NTU• Max SDI = 3.0

“Ground Water”

“Layered removes Liquids”

Applications

Ground water treatment• TDS• Hardness• Metals such as arsenic

GWUI

Surface water• Organics

Pre-Treatment for Nano/RO

Nano / RO

Concentrate

Pre-Filtration for Solids Removal

Pre-Oxidation for Iron/Mg Removal

Microfiltration

Raw Water

SDI < 3

Raw Water

Pre-oxidation

Filtration

Nano / RO

Concentrate

Permeate

Permeate

RO or Nano

Reverse Osmosis• Low energy membranes

provide high efficiency removal

• Removes 97 to 99% of all dissolved compounds

• Blend w/ raw water to meet guidelines and restabilize treated water

Nanofiltration• Removes 60 to 80% of

dissolved compounds• Use for GWUI as treat

entire flow stream• “Softening” filter• Specially formulated

membrane to resist organic (TOC) fouling

Pros and Cons

Pros• Ease of operation• Superior water quality• Reduced footprint• Membrane elements are standardized

Modular units

Cons• Higher energy

costs• High waste

volumes – 60 to 80% recovery

Full Scale Systems

Is It Worth It?

• RO/Nano provides specific function• Often replaces 2 or 3 other processes• Sometimes the only process that will

work

• It is worth looking after your system

Process Applications

RememberMicrofiltration /

Ultrafiltration • “Surface Water” • Turbidity and

particle removal• Crypto/Giardia

barrier• Backwashable

“Spaghetti removes Solids”

RO / Nano

• “Ground Water”• Dissolved

compound reduction

• Do not even think of backwashing

“Layered removes Liquids”

Contaminants

Surface Water• Turbidity• Crypto/Giardia• Iron/Mang/Arsenic• Organics• Hardness

Ground Water• TDS• Hardness• Iron/Mang/Arsenic• Organics• Turbidity

Treatment OptionsContaminant Conventional

ProcessMembrane Process

Turbidity Floc/Coag/Clarifier /Filter

MF

Crypto/Giardia Floc/Coag/Clarifier /Filter

MF

Iron/Mang/Arsenic Chem Precip / Mang Greensand

Chem Precip and MF or RO

Hardness Lime softng/Recarb / Filter

RO

Organics Oxidation and GAC RO

TDS Not readily available RO

System Assessment

• Look at compounds that are process dependant, and then add other processes as required for remaining compounds

Surface Water

Contaminant Membrane Process

Turbidity MF

Crypto/Giardia MF

Iron/Mang/Arsenic MF + Chem Precip

Hardness MF + RO

Organics MF + Enh Coag, or RO

Ground Water

Contaminant Membrane Process

TDS RO

Iron/Mang/Arsenic RO or Chem Precip +MF

Hardness RO

Organics RO

Turbidity MF

GUDI MF

Treatment Quality

• Turbidity• Crypto/Giardia• Iron/Mang/

Arsenic• Organics• Hardness• TDS

< 0.1 NTU

Avg 1 to 4 particle counts

Below guideline limits

< 2 mg/L

< 100

< 500

1. MF Feed to NF for Organics

Process Flow• River water• Upflow clarifier• Microfiltration• Nanofiltration for organics

reduction

Results - MF to NF for Organics

Parameter Raw Water

Clarifier Effluent

MF Perm

NF Perm

TOC (mg/L) 13.1 3.5 3.6 <0.5

Iron (mg/L) 0.32 <0.06 <0.06 <0.06

Manganese (mg/L)

0.039 0.077 0.076 <0.004

TDS 120 170 160 <10

Hardness (mg/L) 96 110 110 <0.5

2. MF-NF for Organics Redn

• River water source• Sedimentation clarifier• Microfiltration• Transfer tank• NF for organics reduction

Results – MF-NF for Org Redn

Parameter Raw Water

MF Feed

MF Perm

RO Perm

Turbidity 2 4.5 0.010

TDS 255 263 264 149

Hardness 198 176 195 88

TOC 15.6 12.3 12.0 0.05

3. MF-NF for Turb, Organics, Hardness

Process Flow• River water• Raw water pond• Microfiltration for

turbidity reduction and crypto / giardia barrier

• Nanofiltration for organics / hardness reduction

Results - MF to NF

Parameter Raw Water

MF Perm NF Perm

TOC (mg/L) 15.8 12.4 <0.1

Turbidity (NTU) 0.86 0.02 <0.1

Manganese (mg/L) 0.005 0.005 <0.002

TDS 751 749 <5

Hardness (mg/L) 527 530 1.0

Summary

• The 1-2 Punch of MF / RO’s, can treat most common contaminants in water.

• Reduced number of processes, generally results in smaller footprint.

• Effluent quality from membrane treatment is consistent.

Questions