Microfiltration / Reverse Osmosis
The 1-2 Punch for Water
Treatment
Presented by:
Don Burgess
DWG Process Supply Ltd.
Material Sizes
RANGES OF FILTRATION PROCESSES
CLOTH & DEPTH FILTERS
MICROFILTRATION
MEMBRANE
TYPE
ULTRAFILTRATION
SCREENS & STRAINERS
NANOFILTRATION
REVERSE
OSMOSIS
LATEX EMULSIONS
METAL IONS
RELATIVE SIZE
OF COMMON
MATERIALS
VOC’S, PCD, SUSP. OIL
DISSOLVED ORGANICS
AQUEOUS
SALTS
RED
BLOOD
CELLS
OIL EMULSIONS
VIRUS
HUMAN
HAIR
PAINT PIGMENT
CARBON
BLACK
BACTERIA
SAND
ATOMIC
RADII
PROTEINS/ENZYMES
PARTICLE SIZE
10-4
10-3
10-2
10-1
1.0
10
102
103
(MICRONS)
PARTICLE SIZE
1
107 (ANGSTROMS)
APPROXIMATE
100
MOLECULAR WT.
10
200
100
20,000
1,000
500,000
10,000
100,000
106
Giardia Cyst
Cryptosporidium
Oocyst
Source: GE Water
Filtration Processes
Microfiltration /
Ultrafiltration
Reverse Osmosis /
Nanofiltration
• Removes turbidity
• Provides barrier to
Crypto/Giardia
• Backwashable
“Surface Water”
“Spaghetti removes
Solids”
• Removes dissolved
compounds
• Typically can not
backwash
• Fouled by turbidity
“Ground Water”
“Layered removes
Liquids”
Microfiltration
How Small is Small?
Pencil Dot (40 µm)
Large Siliceous
Particle (20 µm)
E-Coli
(.45 µm)
Giardia Cyst
(5 - 11 µm)
Cryptosporidium
Oocyst (2 - 5 µm)
[Anthrax Spore]
Typical Bacterium (0.2 µm)
Membrane Pore Sizes – 0.01 to 0.2 micron
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
Pressure Membranes
•
MF Fiber = 0.1 micron
•
PVDF - Oxidant
Resistant (Chlorine,
Ozone & Chlorine Dioxide)
•
Outside – In
•
Rack Mounted Vertically
Source: Pall Canada
Inlet
Section
Immersed Membranes
• UF Fiber = 0.035 micron
• Composite
• Outside – In
• Vacuum
• Mounted in Below or
Above Grade Tanks
Source: www.zenonenv.com
Pressure System (35 MLD - Pall)
Source: Pall Canada
Immersed Wastewater System (Zenon)
Source: www.zenonenv.com
Modular System 1.3 to 2.0 MLD
MF Test Results
Site 1
Site 2
Treated
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
Alum (mg/L)
100
75 to 100
PAC (mg/L)
10
13
Raw Water
Chemical
Dosages
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
Pre-Filtration for Solids Removal
Raw
Water
Nano / RO
SDI < 3
Permeate
Microfiltration
Concentrate
Pre-Oxidation for Iron/Mg Removal
Raw
Water
Preoxidation
Nano / RO
Filtration
Permeate
Concentrate
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
Remember
Microfiltration /
Ultrafiltration
RO / Nano
• “Surface Water”
• Turbidity and
particle removal
• Crypto/Giardia
barrier
• Backwashable
“Spaghetti removes
Solids”
• “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 Options
Contaminant
Conventional
Process
Membrane
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 / RO
Filter
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
TOC (mg/L)
Raw
Water
13.1
Clarifier MF
Effluent Perm
3.5
3.6
NF
Perm
<0.5
Iron (mg/L)
0.32
<0.06
<0.06
<0.06
Manganese
(mg/L)
TDS
0.039
0.077
0.076
<0.004
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
TOC (mg/L)
Raw
Water
15.8
MF Perm NF
Perm
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