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Membrane Solutions for Water and
Wastewater Treatment
Anthony Wachinski, PhD, PE
Pall Corporation
Membrane Seminar
2
Fine Print
This presentation is the work product of Pall
Corporation’s Water Processing Division. No
portion of this presentation may be copied,
published, performed, or redistributed without the
express written authority of a Pall corporate
officer.
© 2011 Pall Corporation.
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3
Membrane Seminar Overview
• Membrane Technologies
• Low-Pressure Membranes
• Low-Pressure Membrane Applications
• Low-Pressure Membrane System Operation
• Overview of US Regulations
• System Processs and Site Considerations
4
At completion of this seminar you will be able to:
• Name the different classifications of membrane technologies used for water treatment
• Know applicable US Regulations affecting small communities
• Discuss low-pressure membrane operation• Identify low-pressure membrane applications• Understand process flow for a membrane water
treatment plant• Identify components of a membrane plant
Course Takeaways
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• NSF International – Certification
• World Health Organization Center for Safe Drinking Water
� NSF 61 –Materials of Construction
� NSF 60 –Water Treatment Chemicals
� NSF 53 – Drinking Water Units –
Health Effects
US Drinking Water Programs
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• Environmental Technology Verification Program (ETV)
� Third party organization - no affiliation with manufacturer.
� Verification of new water treatment technologies to meet manufacturer’s claims.
� Emphasis on performance and cost to treat common problems
US Drinking Water Programs
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• Water is forced through a porous membrane under
pressure while suspended solids, larger molecules, or
ions are held back or rejected.
• Low-Pressure Membranes
• Microfiltration
• Ultrafiltration
• Diffusional Processes (High-Pressure Membranes)
• Nanofiltration
• Reverse Osmosis
• Electrodeionization
Membrane Processes
8
Membrane Processes and Characteristics
Pretreatment
Raw Water Concentrate
Membrane
Permeate
Product Water
5
9
10
Membrane Pretreatment
• RO and Nanofiltration:
– Anti-scalant
– pH adjustment
– Multimedia filter and/or cartridge filters
– MF/UF
• MF and UF:
– Backwashable strainer
– Direct coagulation, Oxidation
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11
• Essentially removes up to 99% of all organic and inorganic constituents.
• Operating pressures range from 30 psi to 1200 psi.
• Removes nitrates, heavy metals, organics, radio nuclides (barium, strontium, cesium).
• Recovery is 75%.
Reverse Osmosis
12
• Loose RO. Removes 80 to 90% of divalent cations and anions, about 50% of monovalent cations and anions and larger organics—natural organic matter.
• Operating pressure- 30 to 150psi
• Typically used to soften water (calcium, magnesium)
• Nitrate, arsenic, NOM, TOC, sulfate
• Recovery – 50%
Nanofiltration
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Surface Water • NOM and TOC Removal• Organics
Groundwater • TDS Removal• Arsenic Removal• Softening• Nitrate removal
Desalination• Brackish and Seawater (with MF pretreatment)
Secondary Effluent• Nitrate removal
Industrial• Cooling tower blowdown (with MF pretreatment)• Boiler Feed water (with MF pretreatment)• Produced water treatment (with MF pretreatment)
High Pressure Membranes Applications
14
Pencil Dot (40 µm)Large SiliceousParticle (20 µm)
Cryptosporidium
Oocyst (2 - 5 µm)
Microfiltration Pore (0.1 µm)
Giardia Cyst (5 - 11 µm)
Relative Particle Sizes
Low Pressure Membranes
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15
• Pore size measured in molecular weight cut-off (MWCO)--water applications--MWCO ranging from 80 kDa to 300 kDa.
• Pressure systems – to about 40 psi.
• Removes particulates, reduces turbidity to < 0.1 ntu
• Removes virus 3-5 log
.
Ultrafiltration
16
• Typically pore size (water) 0.03 to 0.3 micron.
• Pressure systems—to 40 psi.
• Submerged systems—Limited to atmospheric vacuum.
• Removes particles, parasites, bacteria, reduces turbidity to < 0.1 ntu, reduces SDI to <2, removes virus 0.5 to 2.5 log (coagulation)
.
Microfiltration
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17
Microfiltration vs. Ultrafiltration
Typical Summary of Removals MF vs. UF
Microbe Microfiltration Ultrafiltration
Giardia Cysts 4.5-7 log 5-7 log
Cryptosporidium 4.5-7 log 5-7 log
MS-2 Bateriophage
Virus0.5-3.0 log 4.5-6 log
Particle Counts
>2 micron
2-5 micron
5-15 micron
<10/ml
<10/ml
<1/ml
<10/ml
<10/ml
<1/ml
Turbidity - Average 0.01-0.03 ntu 0.01-0.03 ntu
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Surface Water • Pathogen removal
• TOC reduction
Groundwater • Dissolved metal removal (As, Fe, Mn)
• Ground water under direct influence
Secondary Effluent• TSS removal
• Phosphorus reduction
Industrial• Heavy Metals removal
• Mercury removal
Low Pressure Membranes Applications
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• Provide a higher level of protection –absolute barrier--than conventional water treatment for water contamination– if membrane integral, particles > pore size are removed—zero Coliform, E Coli, Giardia, Cryptosporidium.
• Hollow fiber microfiltration—consistent effluent(0.03-0.05ntu) regardless of influent turbidity.
• High recovery – up to 98% for MF.
• Smaller footprint –10% to 20%
Why Membranes?
20
• No sludge disposal issues.
• Minimal chemical use.
• Remote operation.
Why Membranes?
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• Surface Filters
– Cloth Media Filtration (Gravity)
– Disc Filters
• Media Filtration
– Gravel/sand/anthracite in many configurations
Conventional Filtration Technology
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• Granular / Mixed Media
– Irregular Pore Size Distribution
(50 -70 micron between grains)
– Probable Barrier
• Membrane Media
– Controlled Pore Size Distribution (0.1 micron)
– Absolute Barrier
12
LOW-PRESSURE MEMBRANES
Anthony Wachinski, PhD, PE
Pall Corporation
Membrane Seminar
24
Factors to Consider in Membrane Filtration of Water and Wastewater
• Membrane type and rejection properties:
MF/UF, pore size, MWCO
• Membrane material and geometry
• Targeted constituents
• Feed (raw) water quality (temperature)
• Desired treated water quality
• Pretreatment considerations
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Membrane Geometries or Configurations
• Hollow Fiber (MF/UF)
• Spiral Wound (RO, NF)
• Plate and Frame (RO, NF)
• Tubular (UF)
26
Selecting Membrane Technology
• Membrane Material
• Membrane Geometry
• Membrane Packing Density
• Oxidant Resistance
• pH range
• Temperature resistance and range
• Hydrophobicity
14
27
Selecting Membrane Technology (cont.)
• Cleaning options
• Integrity/performance monitoring
• Feed (raw) water quality limitations
• Chemical and pretreatment requirements
• Element, module and system costs
• Manufacturer: experience, competitiveness, technical support
28
Typical Low-Pressure Membrane Composition
• Polyvinylidene Flouride (PVDF)
• Polysulfones (PS)
• Polyacrlonitrile (PAN)
• Polyethersulfone (PES)
• Polyvinyl Chloride (PVC)
• Polypropylene (PP)
For most municipal and industrial applications, high crystalline PVDF membranes are found to be the most economical due to their mechanical strength and chemical tolerance.
15
29
Type of
MembranePore size Membrane spinning
methodRemark
UF
Membrane(< 0.01µm) Non-solvent Induced
Phase Separation
(NIPS)
Generally speaking, both physical and chemical strength is weak.
MF
Membrane0.01µm～0.3µm
(NIPS)
Thermally Induced Phase Separation
(TIPS)
Physical and chemical strength is weak.
Physical and chemical strength is strong.
Effects of Membrane Spinning Methods on the Physical and Chemical Strength of PVDF Membranes
30
TIPS vs. NIPS – polymer structure
TIPS PVDF MF NIPS PVDF Membrane
*Network Structure
-> High strength and High chemical tolerance
*Spherulite Structure
Ref.) Journal of Membrane Science
52 (1990) 239-261
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Comparison of TIPS PVDF membrane chemical tolerance to NIPS PVDF.
TIPS vs. NIPS – Chemical Tolerance
Comparing Chemical Tolerance of PVDF membrane
(5000ppm NaClO + 4% NaOH)aq. @R.T.
0
20
40
60
80
100
120
0 200 400 600 800Soaking Time （（（（Hr））））E
lon
ga
tio
n R
ete
nti
on （（（（%）））） Microza
A Company
B Company
32
Pall’s Hollow Fiber MF Features
• High Porosity, High Permeability
• Removal Rating: 0.1 micron
• Membrane Material: PVDF
• Manufacturing Method: TIPS
• Flow: Outside - In
• High Chemical Resistance (Chlorine, Ozone, Chlorine Dioxide, Ferric & PAC)
• Complete Uniform PVDF Non-Skin Membrane
Microza UNA
17
Cross Section
Outer Surface
Inner Surface
UNA Fiber
34
Membrane Failure
Two modes of failure:
1. Membrane breaches (fiber breaks, integrity issues)
Results in:– Health concerns
– Capacity issues
– Increased labor to repair
2. Irreversible fouling
Results in:
– Capacity issues due to permeability loss
– Increased power costs
18
35
Membrane Breakage
– Abrasion
– Shearing
– Breakage due to foreign objects
Membrane Fouling
– Microbial
– Inorganic
– Organic
– Particulate
36
Modes of Failure – Avoidance
– Membrane Material and method of Manufacture
– Membrane Strength and Elasticity
– Chemical Tolerance
– TIPS manufactured PVDF membranes yielding a high
crystalline structure have proven to be the longest lasting and
most reliable on the market
19
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Small System Evaluation
• Standard, pre-engineered skids
• Quick Delivery
• Ease of Installation
• Pre-engineered system options
• Cleaning systems (CIP, EFM)
• Neutralization Systems
• Seismic rating
• Labor Concerns
• Ease of operation
• Remote monitoring availability
38
Small System Evaluation (cont.)• O&M
• Low Power Demand
• Low Chemical Consumption
• Integrity Testing – ability to meet 3 micron requirement
• Ease of breach detection
• Ease of repair
• Certifications/verifications—NSF61/60/53 Environmental
Technology Verification (ETV) State – in place!
20
39
Large System Evaluation
• Customized Scope of Supply
• Flexibility in components, programming
• Redundancy options
• Minimal Footprint
• High Recovery (option to recover backwash waste)
• Labor Concerns
• Ease of operation
• Remote monitoring availability
40
Large System Evaluation (cont.)
• O&M
• Low Power Demand
• Low Chemical Consumption
• Integrity Testing – ability to meet 3 micron requirement
• Ease of breach detection
• Ease of repair
• Certifications/verifications
21
LOW-PRESSURE MEMBRANE
APPLICATIONS
Anthony Wachinski, PhD, PE
Pall Corporation
Membrane Seminar
42
Surface WaterGround Water
Secondary EffluentSea / Brackish Water
SOURCES
CONTAMINANTS
REQUIREMENTS
TurbidityCryptosporidium & Giardia
Fecal Coliforms & Virus Organics (TOC, NOM, T & O)
Inorganics (Fe, Mn & As)
MF/UF Water Exceeds National/State Standards
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Remove Particulate
Turbidity < 0.1 NTU
SDI < 2 (Pre-RO)
Remove Microbiologicals
Cryptosporidium, Giardia, Animal Parasites, Bacteria,Virus
Remove Organics
TOC (Total Organic Carbon), NOM (Natural Organic Matters), Color, Taste & Odor, Others with proper chemistry
Remove Inorganics
Fe, Mn, As with proper chemistry
Separation Goals
44
Water ClassificationsGroundwater Groundwater Surface Water Surface Water Secondary Effluent
Parameter Under the Influence
of Surface water
(LT2)
High Iron and Mn Low TOC or
Turbidity
(LT2)
High TOC or
Turbidity
(LT2)
Secondary
Wastewater Effluent
Contaminants Turbidity&
Microbial
Pathogens
Iron and Mn Turbidity &
Microbial
Pathogens
Turbidity &
Microbial
Pathogens
SS & Pathogens
Pretreatment None Direct Oxidation &
Precipitation
None (400mm
strainer)
Direct Coag. OR
Coag. & Clarif.
Disinfection &
Strainer
Filtered Water
Quality
<0.05 NTU
ND Giardia
&Crypto
<0.05 NTU
Fe & Mn <0.05 ppm
<0.05 NTU
ND Giardia
&Crypto
<0.05 NTU ,ND Giardia
&Crypto, 35 %
Reduction of TOC
SDI<2
<0.05 NTU
23
45
Surface water is characterized by
– Higher percentage of suspended solids and
turbidity
– Higher percentage of organics
– Higher percentage of microbials
– Higher variability depending on seasons,
precipitation and external factors
Surface Waters
46
Conventional treatment technologies have remained unchanged for years. Are impacted by changes in the influent quality of source water. Do not provide a barrier to pathogens. Provide good effluent water quality most of the time.
Cannot meet all of the requirements of the safe water drinking act, namely LT2—remove Cryptospordium and meet DBP requirements.
Conventional technologies have little room for improvement (enhanced coagulation—sludge disposal, extended settling time—large footprint, new treatment chemical options DBP formation )
Conventional Treatment of Surface Water
24
47
Conventional vs. Low Pressure MF/UF
Surface Water Treatment
DisinfectionInorganic
Coagulant
Addition
RawWater
Coagulationand Mixing Clarification Filtration
DistributionSystem
DisinfectionRaw
Water
DistributionSystem
MF/UF
Low Pressure Membrane Alternative
48
Total Organic Carbon Reduction
Disinfection
Inorganic
Coagulant
Addition
RawWater
Coagulationand Mixing Clarification Filtration
DistributionSystem
DisinfectionRaw
Water
DistributionSystem
MF/UF
Low Pressure Membrane Alternative
Inorganic
Coagulant
Addition
DisinfectionInorganic
Coagulant
Addition
Raw
Water
Coagulation
and Mixing Clarification MF/UFDistribution
System
OR, Direct Coagulation with Low Pressure Membranes
25
49
Pressurized Membranes TOC Removal
0
10
20
30
40
50
60
70
80
Alc
oa
Azu
sa
Ba
ke
rsfie
ld
Bru
sh
y C
ree
k
Clo
vis
Ft
Pa
yn
e
Ga
insvill
e
GB
RA
Ke
rrvill
e
Pflu
ge
rvill
e
Ve
rno
n
Site
Av
e T
OC
Re
du
cti
on
(%
)
50
Pressurized Membranes Case HistoriesProject Source Coagulant Dose
(mg/L) HRT (min)
TOC (mg/L)
% TOC Reduction
Bakersfield, CA River PACl 15-25 60-120 3-5 35-45
GBRA, TX River Fe2(SO4)3 60 10 1.8-4.8 35
Kerrville, TX River Fe2(SO4)3 20 9-14 2-4 10-71
Billings, MT River FeCl3 25 120 1.1-6.9 23-40
Alcoa, TN River Alum 15 13 0.9-2.5 11-61
Nobleford, BC Reservoir PACl 5-50 20 2.6-3.2 3-26
Pflugerville, TX Fe2(SO4)3 45 0.5 1.7-6.1 11-95
Brushy Creek, TX FeCl3 40 10 2.8-3.1 13-29
Gainsville, GA Creek Alum 20 10 3.9 74
Murfreesboro, TN River ACH 30 43 2.5 ---
Lancaster, PA River Alum >240 2 ---
Azusa, CA River/Canal ACH 15-20 5-15 2-3 30-40
San Patricio, TX Lake Alum >240 3-6 ---
Glendale, AZ SRP Alum 4-13 >240 2.1-3.5 ---
Clovis, CA Canal FeCl3 5-8 5 3.2 30-60
Vernon, BC Lake/Creek PACl 20 20 4.2-8.4 13-60
Ft Payne Reservoir PACl 15 10 1.7-1.9 37
26
51
For TOC Removal – depends solely on reduction goals.
Typically:• Coag/Settle achieves up to 50% reduction in TOC
• Direct Coag achieves up to 50% reduction in TOC
All things being equal, Direct Coagulation is highly preferred
because of significantly lower capital cost (less equipment)
and lower O&M expenses.
COAG/SETTLE OR DIRECT COAG?
52
Higher quality water being applied to the membranes allows
for full flux potential, decreases number of membranes
required and therefore lowers system capital $$$.
Organics / inorganics removed during coag/sed process, MF
removes turbidity to less than 0.1 ntu, bacteria, and some log
virus).
For small systems this is not necessary – benefit of less
equipment (coag, floc, settling) greatly outweighs flux benefit.
Moreover, effluent quality is the same!
COAG/SETTLE OR DIRECT COAG?
27
53
Ground water is characterized by
– Low turbidity from filtration through many
geological layers
– A higher content of dissolved contaminants like
iron, manganese, and arsenic
– A fairly stable water chemistry unless the water is
“under the influence”
TREATING GROUND WATERS
54
Pressure sand / green sand technologies –with oxidant,
remove iron and manganese. Pressure for iron. Green
sand for manganese.
Pressure sand and green sand technologies not designed
to treat GWUDI ( turbidity) and arsenic.
CONVENTIONAL TREATMENT OF GROUNDWATER
28
55
ARSENIC REMOVALSoluble Arsenic is removed using a ferric salt to complex the arsenic. MF
provides “the barrier” and removes the arsenic floc particles.
This approach is cost competitive with adsorptive media and provides
lower O&M (regeneration / disposal of media).
56
Soluble Iron and Manganese are removed by oxidization. MF provides
“the barrier” and removes the precipitated iron/manganese to < 0.05 mg/L.
PVDF membranes can handle a variety of oxidants.
MANGANESE REMOVAL
29
57
IRON REMOVAL
58
GROUND WATER UNDER DIRECT INFLUENCE
GWUDI poses the threat of Cryptosporidium/Giardia as well as other
surface water pathogens. Therefore, it should be treated as surface water
is treated.
30
59
Secondary effluents can be characterized by
– Higher percentage of suspended solids and
turbidity
– Higher percentage of organics
– Higher percentage of microbials
– Higher percentage of inorganics
TREATING WASTEWATER
60
Conventional treatment technologies have remained
unchanged for 100 years –activated sludge. Objective
to meet NPDES permit –20/20 or 5/5.
Nutrient removal –nitrogen and phosphorous and
water reuse restrictions – droughts/cost of water
require new technologies—(integrated membrane
systems (MF/RO).
CONVENTIONAL TREATMENT OF WASTEWATER
31
61
Further treat secondary or tertiary effluent to meet Title 22 regulation and/or as pretreatment for reuse.
Phosphorous reduction via coagulation.
MEMBRANE APPLICATION ON WASTEWATER
62
MF/UF EFFECT ON SECONDARY EFFLUENTParameter Secondary Effluent MF Filtrate/Permeate
Projected Average mg/L (Design Goal)
(except where noted)
BOD5 20 < 5
COD 37 (max 42) < 10
TOC 12 < 4
TSS < 10 < 0.1
TKN 4 < 4
NH3-N 0.1 (max 1.0) < 0.1
P (total) < 3 (max 10) < 0.10
Ortho-P < 2 < 0.10
Turbidity < 10 < 0.1
Fecal Coliform (CFU/100 mL) -- 0
32
Low-Pressure Membrane
System Operation
Anthony Wachinski, PhD, PE
Pall Corporation
Membrane Seminar
64
Upper
Bonded
Section
Membrane
Bundle
Module
Housing
Module Feed
Pure
Filtrate
Lower Potting
Upper Potting
A hollow
fiber
MembraneModule
33
65
Module Inlet
Feed enters through holes
Fiber ends are sealed.
Allows air enters for AS
66
FORWARD FLOW OPERATION
34
67
As cumulative water throughput increases over time, fouling increases which raises trans-membrane pressure (TMP).
Given the inherent limits of the MF/UF modules (~3 bar) and economic concerns (raised power consumption), cleaning methods are utilized to keep the system running optimally.
These cleaning methods include:
– Flux Maintenance (commonly referred to as “backwash”)
– Enhanced Flux Maintenance (or Chemically-enhanced
backwash)
– Clean-in-Place
MEMBRANE CLEANING OPERATIONS
68
Flux Maintenance
TMP
(∆P)
Time
Longer cycle with “Flux Maintenance” (Backwash, RF, AS, etc.)
TMP (∆P)increases by time
35
69
Flux Maintenance is an automated process that is the first and most frequently used cleaning method used for TMP reduction.
Flux Maintenance consists of several operations that are used in conjunction to reduce TMP.
• Air Scrub
• Forward Flush (Every 15 -30 mins.)
• Reverse Flush
70
AIR SCRUB
36
71
FORWARD FLUSH
72
REVERSE FLUSH
37
73
• Although not used on every system, most systems use an intermediate cleaning step called Enhanced Flux Maintenance (EFM) or Chemically Enhanced Backwash (CEB) to reduce fouling and maintain lower TMP.
• EFM is typically performed weekly, but sometimes as often as daily.
• During EFM, a solution of sodium hypochlorite is recirculated through the module for up to 90 minutes.
• EFM’s are designed on case-by-case basis
Enhanced Flux Maintenance
74
EFFECT OF MAINTENANCE WASHES ON TMP
0
5
10
15
20
25
30
35
40
2/13 2/14 2/15 2/16 2/17
Run Time (Days)
TM
P (p
sid
)
TMP
38
75
• Even with Flux Maintenance and EFM procedures, the TMP will steadily increase until it reaches the point where the membranes have to be chemically cleaned for the TMP to return to the original level.
• Consists of two phases : caustic clean and acid clean
• Typically performed once per month
CLEAN-IN-PLACE
76
CLEAN-IN-PLACE
39
77
CLEAN-IN-PLACE
78
CLEAN-IN-PLACE
40
79
EFFECT OF CIP ON TMP
0
5
10
15
20
25
30
35
0 5 10 15 20 25 30 35 40 45
Run Time (days)
PSI
TMP
80
Integrity Testing of Low-Pressure
Membranes
41
81
Integrity Testing: Direct vs. IndirectDirect Indirect
Definition
A physical test applied to a membrane unit in order to identify and isolate integrity breaches
A test primarily based on monitoring water quality as a surrogate of membrane integrity
Examples
•Pressure-based tests (e.g., pressure decay, diffusion flow, etc.)
•Marker-based tests
•Turbidity monitoring
•Particle count and particle monitoring
Significance
Must be used to verify removal efficiency in routine operation
Must be used for continuous integrity monitoring if direct method cannot monitor IT continuously
82
Regulatory Framework
• Removal credit granted based on the lesser of
– (a) product-specific challenge test and
– (b) integrity testing
• The granted removal credit cannot exceed what can be verified through integrity test (IT).
• Must undergo periodic direct integrity testing & continuous indirect integrity monitoring.
• The direct IT must meet certain criteria.
42
83
• Direct Integrity Testing (DIT)– Resolution: ≤ 3 microns
– Sensitivity: max LRV taking concentration factor into the account
– Frequency: once per day (the state may approve less frequent testing on the basis of demonstrated process reliability, use of multiple barriers, or reliable process safeguards
– Control Limit (CL), or integrity test result which indicates problems and triggers response
– Reporting requirement
• Continuous Indirect Integrity Testing– Continuous sampling interval ≤ 15 min.
– CL for turbidity monitoring: < 0.15 NTU in a period of longer than 15’
– Incidents exceeding CL trigger direct IT
IT Requirements in the LT2ESWTR
84
Dilution Factor of A Broken Fiber
100
1,000
10,000
100,000
1,000,000
0 10 20 30 40
Pressure Differential, psid
Dil
uti
on
Facto
r (F
D)
10 mgd
5 mgd
1 mgd
0.5 mgd
0.1 mgd
(A completely cut fiber with shortest flow path for the breakage)
FD = Q/q
43
85
Direct IT
Detect
Pressure Hold Test on Block of Modules
• Vent filtered water side of module
• Pressurize feed side with 25-30 psig of air (Displaces water in shell)
• At air pressure set point, turn air off
• PLC measures rate of pressure decay
• Pass: <0.05 psi/min for 25 modules; (0) broken fibers: Decay = 5 ml/min for 25 modules (diffusion flow)
• Broken Fiber: Decay = 1000 ml/minAir In
30 psig
15 psig
86
Direct ITIsolate
• Find damaged module by looking for air bubbles (see transparent coupling)
Repair
• With the module remaining in place, remove cap, and find the broken fiber by looking for air bubble stream.
• Seal off fiber by inserting a pin
Retest & Return to service
Total time is typically less then 25 minutes!
44
87
Transparent Coupling • Found on filtrate/permeate end of module• Find damaged module by looking for air bubbles
88
How Is Direct IT Regulated?
• LT2ESWTR does not require the use of particular direct IT method for rule compliance, but requires the method used to satisfy specified performance criteria
• Three performance criteria are specified:
– Resolution
– Sensitivity
– Testing Frequency
45
89
Performance Criteria for Direct IT
Criterion Definition Value
ResolutionThe smallest integrity breach that is detectable
≤≤≤≤ 3 µµµµm
SensitivityThe maximum LRV that is verifiable
Site-specific
Testing FrequencyHow often a direct IT is conducted
≥≥≥≥ once per day
90
Direct IT: Resolution
Liquid Phase
Gas Phase
Liquid Phase
Gas Phase
Membrane Pore
b. P≥ PB
Air bubbles through pores
a. P < PB
Air passes through pores only
via diffusion
46
91
0.1
1.0
10.0
100.0
0 10 20 30 40
Pressure Differential, psid @ 4 deg. C
Po
re S
ize
, m
icro
me
ters
3 µµµµ m
Direct IT: Resolution
92
Direct IT: Sensitivity
• What:– Ability to detect a integrity breach at the level that the
system can have maximum LRV.
• Criterion:– Site-specific, but must equal to or greater than the
granted removal credit.
• How:– Quantify removal efficiency by establishing the
relationships of testing parameter(s) and removal efficiency.
47
93
Direct IT: Testing Frequency
• For compliance with LT2ESWTR, the membrane unit is required to be tested at least once per day
• States with primacy have discretion to determine testing frequency
• For non-compliance purpose, a less frequent testing may be permitted
• The minimum testing frequency is to balance the need of safeguard system integrity and production
94
Example: Pressure-Hold Test
• Water by-pass through a membrane defect is related to the air flow through the same defect during pressure-hold test, which is in turn related to pressure decay rate.
• Hydraulic modeling and/or empirical relationships based on experiments can be used to establish the relationship.
}
)]ln(2[
log{)(
)()log(log505.1
5.0
2
1
5.02
2
2
15.0
p
p
D
fLD
L
PDRD
pp
M
RT
PVVCF
QLRV
H
WW
+
+−
+∆×
+=µ
48
95
San Patricio, TX: Pressure-Hold Test
Source: Sethi et al., 2003 (AWWARF RFP2681)
96
Bacillus s. Removal at San Pat., TX
Data Source: Sethi et al., 2003 (AWWARF RFP2681)
0
1
2
3
4
5
6
7
8
1 3 6 8
No. of Cut Fibers
LR
V fo
r Bacillu
s s
..
49
97
Bacillus LRV v PDR for San Patricio, TX
98
50
99
Sensitivity vs. Testing Pressure
0
500
1000
1500
2000
0 10 20 30 40 50
Inlet Pressure, psia
Air
Flo
w,
mL
/min
.@25o
C Calculation
Experiment
Laminar Transition
100
How Is Indirect IT Regulated?• Turbidity monitoring is default technology
• The approval of monitoring technologies other than turbidity is in the discretion of states
• The filtrate from each membrane unit must be monitored independently
• The filtrate from each membrane unit must be monitored continuously (i.e., ≤ 15 min.)
• A performance-based upper control limit (UCL) must be established such that readings exceeding UCL would trigger direct IT
• All readings exceeding UCL must be reported on monthly basis
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Example : Particle Counts
• Every single count is inherently a random event
• The background counts vary around a statistical mean
• Question:
– How to set alarm setpoint (i.e., an UCL) to indicate an integrity
breach?
– If a count is greater than UCL, what is the probability of a false
alarm?
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Indirect IT: Sensitivity & Reliability
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Indirect IT: Sensitivity & Reliability
Sethi et al., 2002 (AWWARF RFP2681)
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Frequency: Risk-Based Approach
• Test frequency should relate to the risks of integrity breach
• Risk is the product of occurrence and severity of integrity breach
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Conclusions
• LT2ESWTR has significant influence on regulating membranes,
especially on integrity testing
• Testing pressure for pressure-based direct IT is the most important
parameter to meet resolution criterion set in LT2ESWTR
• Full-scale plant challenge data is the most reliable indicator for the
sensitivity of an IT method
• The frequency of IT should be determined using a risk-based approach
• For indirect IT, attentions need to be paid to sensitivity and reliability of the test.
Overview of US Drinking
Water Regulations
Membrane Seminar
Anthony Wachinski, PhD, PE
Pall Corporation
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Small vs. Large Water Systems
Definition depends on Regulation!
• Small = Systems serving < 10,000 customers:
• 95% of community water systems.
• 21% of the population.
• Large = Systems serving > 10,000 customers:
• 5% of community water systems.
• 79% of the population.
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ONLY PUBLIC WATER SYSTEMS ARE
SUBJECT TO DRINKING WATER
STANDARDS!!!!
Community Public Water Systems• Serves 15 service connections-year-around residents
• Serve year-round residents > 25 residents
• Municipal systems, mobile-home parks, apartment
buildings, condominiums with own water supply
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Community Public Water Systems
• Serves 15 service connections-year-around residents
• Serve year-round residents > 25 residents
• Municipal systems, mobile-home parks, apartment buildings, condominiums with own water supply
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Non-Community Public Water Systems
1.Non-Transient
• Own water supply
• Serves >25 of same persons
• Persons do not reside/ attend more than 6 months
• Schools, factories, hospitals
2. Transient
• Do not serves > 25 over 6 month
• Parks, motels, hotels, restaurants with own water supply
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220,000 public water systems regulated under USEPA and SWDA Rules
• US Population 300,000,000
• 160,000 non-community systems
• 60,000 community systems.
– Very small systems serve less than 500 people
– Small systems serve 501 - 3,300 people
– Medium systems serve 3,301 - 10,000 people
– Large systems serve 10,001 - 100,000 people
– Very large systems serve > 100,000 people
US Water System Statistics
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Major Drinking Water Contaminants
• Microbes:
� viruses, bacteria and parasites
• Disinfection By-Products (DBPs):
� Total Trihalomethanes (TTHMs)
� Total Haloacetic Acids (THAAs):
• DBP precursors:
� natural organic matter; humic substances (soluble and colloidal)
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Major Drinking Water Contaminants
• Synthetic Organic Chemicals (SOCs):
� Pesticides, solvents, monomers, pharmaceuticals, endocrine disruptors,
hormones
• Inorganic Chemicals:
� arsenic, asbestos, cadmium, chromium, Cu, cyanide, fluoride, Pb, Hg, nickel,
nitrate, nitrite
• Total Dissolved Solids (salinity):
� sulfates, chlorides
• Radionuclides
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Focus of US Regulations
� Microbial - Parasites, Bacteria, Virus (8 contaminants)—Immediate Health Risk!
� Chemical Contaminants – long-term health risk
� Synthetic Organic Chemicals (60)
� Inorganics - Lead, Copper, Arsenic (19)
� Radionuclides (4)
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Current Regulatory Activities in Drinking Water from Surface Sources
• Surface Water Treatment Rule (SWTR)—1989
• Interim Enhanced Surface Water Treatment Rule (IESWTR)—1998
• Long Term I Enhanced Surface Water Treatment Rule(LTI)--2002
• Long Term 2 Enhanced Surface Water Treatment Rule (LT2) and Disinfection/Disinfection By-Product (DBP) Rule. (2006)
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• Application -- to all public water systems using any surface water or groundwater under direct influence of surface water
• Disinfection--must disinfect and may be required by the state to filter, unless certain water quality, source requirements, and site-specific conditions can be met
• SWTR (1989):
– Turbidity < 0.5 NTU in more than 95% samples and < 5 NTU all time
– Removal of Giardia of 3-log (99.9%)
– Removal/inactivation of viruses must 4-log (99.99%)
Surface Water Treatment Rule (SWTR), IESWTR, LT1ESWTR
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Surface Water Treatment Rule (SWTR), IESWTR, LT1ESWTR (cont.)
• IESWTR (1998)/LT1ESWTR (2002):
– Removal/inactivation of Cryptosporidium of 2-log (99%)
• Based on the inactivation requirements above, the state defines level of disinfection required, depending on technology and source water quality
• Sampling frequency --depends upon the system size
• All systems must be operated by qualified operators as determined by the state (operator certification)
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LT2ESWTR/D/DBP
• Long Term 2 Enhanced Surface Water Treatment Rule (LT2) and
Disinfection/Disinfection By-Product (DBP) Rule:
– Regulate Cryptosporidium parvum in addition to the other
microbes
– Regulate disinfectants and DBPs
– Regulation of Microbes (M) must not increase risks from DBPs
and regulation of DBPs must not increase risks from microbes
– Increased emphasis on source water quality
– Increased emphasis on most appropriate technology to reduce
risks of Cryptosporidium and DBPs
– Membrane technology is considered highly promising for
achieving both M and DBP control
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• Initial system monitoring – two years of monthly sampling for Cryptosporidium (alternative monitoring for small filtered systems)
• Treatment– Filtered water systems: classified into 1 of 4 bins
based on monitoring results. Systems that are not in the lowest bin will require up to 3-log additionalcrypto inactivation
– Unfiltered systems: must provide at least 2- or 3-log inactivation of Cryptosporidium
– A “microbial toolbox” is provided for systems to selecting treatment and management strategies
Introduction to LT2ESWTR (2006)
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• Uncovered finished water reservoirs: treat or cover
• Disinfection benchmarking – systems must review their current level of microbial treatment before making significant change in their disinfection practice for compliance of 2 Stage D/DBP rule.
• Monitoring starting dates are staggered by system size. The largest systems (serving at least 100,000 people) began monitoring in October 2006 and the smallest systems (serving fewer than 10,000 people) began monitoring until October 2008.
• After completing monitoring and determining their treatment bin, systems generally have three years to comply with any additional treatment requirements. Systems must conduct a second round of monitoring six years after completing the initial round to determine if source water conditions have changed significantly.
Summary of LT2ESWTR
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Average Crypto Conc.
In Source WaterBin Classification
< 0.075/L
0.075/L - < 1.0/L
1.0/L - < 3.0/L
≥ 3.0/L
1
2
3
4
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Bin No.
Addition Treatment Required for System Using
Conventional Treatment , DE filtration, slow sand filter
Direction Filtration Alternative Filtration Technologies (including membrane filtration)
1
2
3
4
No additional requirements
1-log
2-log
2.5-log
No additional requirements
1.5-log
2.5-log
3-log
No additional requirements
≥ 4-log total*
≥ 5-log total**
≥ 5.5-log total**
* May use any or combination of technologies from the toolbox.
** Must achieve ≥ 1 log removal by O3, ClO2, UV, membranes, bag/cartridge filters, or bank
filtration.
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LT2ESWTR ToolboxProcess/Operation Credit Granted
Watershed Control 0.5-log
Off-stream Storage 0.5-log for 21-day retention, and 1.0-log for 60-day retention
Sedimentation with Coagulants
1.0-log if turbidity > 10 NTU & overflow rate < 1.6 gpm/ft2
Two-stage Lime-softening 0.5-log if 2nd stage uses a coagulant
Lower Finished Water Turbidity
0.5-log if <0.15 NTU in >95% 4-hr sample (combined)
1.0-log if <0.15 NTU in >95% 15-min sample (individual filters)
River Bank Filtration 0.5-log if wells located >25’, and 1.0-log if wells located >50’
Bag & Cartridge Filters 1-log for bag & 2-log for cartridge as proved by challenging test
Slow Sand Filter 3-log as primary treatment; 2.5-log as post-treatment
Membranes Proved through challenge test & verified by direct integrity testing
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• Membrane filtration is one of technologies listed in the “microbial toolbox”
• The rule does not give membrane filtration a removal credit as for other technologies. Rather, it states the credit is granted as “equivalent to removal efficiency demonstrated in challenge test for device if supported by direct integrity testing”
• Specific requirement on challenge test
• Establishment of Quality Control Release Value (QCRV) on Non-destructive Performance Test (NDPT) to verify the removal efficiency of membrane filters
• Direct and Indirect Integrity Test (IT)
LT2ESWTR PROVISIONS FOR MEMBRANES
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• Utilities are required to conduct an Initial Distribution System Evaluation (IDSE) to locate where the highest DBPs are in the system.
• Compliance with MCLs for TTHM and HAA5 is based upon the monitoring of those locations, referred as locational running annual average (LRAA).
• Each system is also required to determine if it exceeds an operational evaluation level (OEL), which is established using the previous compliance monitoring results and used as an early warning of possible future MCL violations
Summary of Stage 2 D/DBP Rule
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Near-Term Implications
• Finalization of Stage 2 D/DBP Rule & LT2ESWTR will fuel the continuous growth in drinking water market as utilities struggle for compliance
• The advantages of membrane filtration are its ability to help utilities comply with multiple drinking water regulations with more robust and reliable operations
• As utilities have to rely less on chemical disinfection for compliance, and at the same time the requirements to control microbial contaminants get higher, membrane filtration provides good alternatives for compliance
• Technologies for cost-effective TOC removal will get a boost from rule compliance of Stage 2 D/DBP Rule
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FBRR
• Filter Backwash Recycling Rule
• Prevent Cryptosporidium in Finished Drinking Water
• Minimize risk of recycle on Plant Performance.
• All Recycle Streams treated – process must achieve 2-log Crypto Removal
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Groundwater Rule
• Microbial regulation
• Undisinfected GW
• Identify high risk groundwater sources for fecal contamination.
• Targets bacteria and virus
• Applies to GW sources – 15 connections or 25 individuals for 60 days
• Applies to mixed GW/ SW sources-
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System Process and
Site Considerations
Membrane Seminar
Anthony Wachinsk, PhD, PE
Pall Corporation
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Pall AriaTM Microfiltration Packaged Systems
Pall AriaTM systems are complete microfiltration packaged plants that are designed to be “plug and play”. They are capable of being installed and producing high quality water withina very short time, often within a few days.
On a basic system, the installation can literally be as simple as placing the system skid on level ground, providing one power drop, a source of air, raw water, filtered water outlet, potable water for CIP, and waste connections.
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Standard Packaged Systems Components
• Microfiltration modules/rack
• Complete control system
• Integrity test
• Clean-in-Place system
• Feed/recirculation tank with LIT
• Feed/recirculation pump with VFD
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Standard Packaged Systems Components
• Automatic backwashing strainer
• Backwash tank with LIT
• Backwash pump with VFD (AX-1, -2 have bladder tank instead)
• All interconnect piping and wiring
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Optional Packaged Systems Components
• Turbidimeters (on-skid or off-skid)
• Control system options (PLC, NEMA4, SCADA)
• Air compressor system
• Chemical neutralization system
• Fully automated EFM/CIP system
• Backwash recovery options
• Pre-treatment options
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Pall Aria Packaged Systems
Pall offers two microfiltration packaged systems:
– Pall Aria AX
• Designed for smaller flow rates (<180 gpm)
• Simpler design, less automated
– Pall Aria AP
• Flows up to 1.25 MGD
• Fully automated
• More custom options
Pall Aria AX-2
The next slides will discuss the site and installation considerations of Pall Aria AP systems, although mostly everything applies to AX systems as well.
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AP4 with Off-Skid Rack
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Integration of AP Systems into the Overall Process
Two Major Basic Control Schemes
A. Constant Flow Mode
B. Constant Level Mode
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Advantages
•Simple operation with minimum controls
•Chemical addition by metering pumps is simplified,
as they can be set to match the flowrate, then turned
on/off when the appropriate system starts/stops.
•Lowest capital cost
Disadvantages
•On/off cycling of pumps and equipment
•Higher energy costs
•Variable tank levels
Constant Flow Control
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Constant Level Control
Advantages
•Less on/off cycling of pumps and other equipment
•Smoother and more consistent operation
•Typically lower operating costs, since pumps only
run at the speed required
•Constant tank levels
Disadvantages
•More complicated system
•Higher initial capital cost
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Advantages
•Simple operation with minimum controls
•Chemical addition by metering pumps is simplified,
as they can be set to match the flowrate, then turned
on/off when the appropriate system starts/stops.
•Lowest capital cost
Disadvantages
•On/off cycling of pumps and equipment
•Higher energy costs
•Variable tank levels
Constant Flow Control
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Installation Requirements
� The AP skid and any ancillary equipment must be positioned and properly anchored.
� The membrane module rack must be installed, anchored, and the interconnect piping between the skid and the module rack must be installed.
� Connections � Power � Compressed Air � Raw Water Feed � Filtrate Out � Waste
� High Flow Drain � Misc Drain
� Warm Water Connection to Feed/Recirc Tank for EFM/CIP � Phone Line if Remote Access or Alarm Dialer are required
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Power Drops• Each AP Control Panel
• Master Panel if multiple units
• EFM/CIP Panel (option)
Water Heater
• Neutralization Panel (option)
• Compressor
• Additional 120V drop required for internal drier on some compressors
• Miscellaneous off-skid equipment
No MCC required!
For standard AP systems, VFDs and motor starters are included.
Each Panel has its own fused disconnect. Therefore, only a main disconnect may be required. (Check Local Codes)
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Wiring• All on-skid instruments, pumps, etc. on AP skids are fully wired and
factory tested.
• Contractor to land off-skid wiring to terminal blocks in the AP Panel.
• Off-skid equipment may require local starters/disconnects
• Devicenet cable to be supplied and installed by Contractor
• Between AP Panel and EFM/CIP Panel
• Between AP Panel and Master Control Panel (multiple APs)
• Between other control panels and Master Control Panel (if applicable)
• Ethernet to PC for data logging and remote access, if applicable
• Ethernet to Plant SCADA, if applicable
• Phone line for remote access or auto-alarm dialer
• Off-skid equipment
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Waste HandlingAll drains must gravity flow
• Drains can’t flow uphill!
Waste streams
1. Air Scrub/Backwash/Forward Flush – No chemical addition
– Typically 1 ½ minutes every 15 to 30 mins.
– 60 second air scrub with 8 gpm/module backwash
– 20 to 30 second forward flush @ 18 gpm/module
Example: Typical AP-4 producing ½ MGD
240 gpm for 60 sec. (Backwash)
540 gpm for 20 sec. (Forward Flush)
Total chem free waste ~420 gal (1.5 min)
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Disposal Options (Chemical-free waste)
• Backwash recovery with secondary AP system
• Publicly Owned Treatment Works (POTW)
• Sedimentation (DAF) pretreatment
• Septic system (remote areas)
• Evaporation pond (State DOH)
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Waste Streams (continued)2. Clean-in-Place (CIP)
– Typically every 1 – 2 months
– Pumped to drain down to about 5 – 10% of tank levels, then gravity drained
– Two Cleaning cycles:
• 1% Caustic (NaOH) + 1000 ppm NaOCl, followed by 1 – 2 rinses
• 2% Citric Acid, followed by 1 – 2 rinses
Example: Typical AP-4 producing ½ MGD
460 gallons of NaOH/NaOCl solution
1 rinse of 460 gallons
460 gallons of 2% Citric Acid
2 rinses of 460 gallons
Total chemical waste = 2300 gallons
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Disposal Options (Chemical waste)
• POTW
• Neutralization, then dispose
pH Neutralization
Dechlorination
• Truck off
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Waste Streams (continued)3. Enhanced Flux Maintenance (EFM)
– Typically 1 to 3 days
– Pumped to drain down to about 5 – 10% of tank levels, then gravity drained
– 200 – 500 ppm NaOCl, followed by 2 rinses
Example: Typical AP-4 producing ½ MGD
460 gallons of 500 ppm solution
Two rinses of 460 gallons
Total chemical waste = 1380 gallons
Disposal Options (same as CIP)• POTW
• Neutralization, then dispose
pH Neutralization
Dechlorination
• Septic
• Truck off
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Waste Streams (continued)
4. Miscellaneous Drain• Strainer Backwash
• Turbidimeter flows
• Tank Overflows
Cannot connect the two waste outlets unless an air gap or check valve is installed on the misc. drain.
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Existing Building
• How much can you reuse?
• Space requirements
• 36” around all equipment
• 11’ minimum ceiling height
• Will all equipment fit in one room? Multiple room layout?
• Moving equipment into building
• Infrastructure
• Hydraulics
• Chemical dosing (disinfection, pretreatment)
• Utilities (460V 3-phase electrical)
• Pressurized Air supply
• Floor loading
• Security Measures
• Seismic Considerations (Building and MF unit)
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Installation• Typically, contractor installed
• Pall provides installation manual
• Pall Supervision (optional)
• Skidded Systems come crated
• All fit through garage door
• Require forklift (AP-6 > 5000 lb.)
• Pall Service (Standard 5 days)
• Check, flush, set-up system
• Full day of operator training
• Optional Pall Service
• Installation assistance
• Performance Test
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System Control and Integration• AP Standard: Allen Bradley Logix 5000
series PLC & Panelview 700+HMI• Controls all MF processes
Backwashing
EFM/CIP
Integrity Test
• Can control entire WTP• How integrated?
• How sophisticated?
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System Control and Integration
• Standard “Custom” Control
• Programs exist for:
Raw Water Pumps
Distribution Pumps
Chlorination
Pre-treatment
• SCADA PC Option: Dell Latest offering running RSView HMI
• Datalog
• Remote Support
• Backup
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Process
• Supply – Require 5 psi (pump, gravity feed from source
• Pretreatment – Dependent on application
• Post treatment – Disinfection
• Pall Scope?
• Distribution – Tankage?
• Sizing (downtime of MF)
• Max backpressure 5 psi (pump?)
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Operation and Maintenance• PLC control of MF (ancillary equipment optional)
• Operator Requirements
• Necessary to CIP (typically 1 day/month)
• Integrity Testing and fiber pinning
• Maintain Chemical levels
• Membrane replacements every 10 years
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Pall AriaTM Systems
While we’ve focused on packaged systems (AP and AX), the full Aria product line includes much more:
• Pall Aria Custom systems
• Pall Aria IMS
– MF + RO
– MF + NF
• Pall AriaPRO packaged RO systems
• Pall Aria Mobile (PAM) systems
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Pall AriaTM Custom Systems
• Capacities from 2 MGD to >100 MGD
• Fully customized scope of supply
– Components: strainers, pumps, control systems
– Redundancies and Expandability
– Service
– Programming (coordination with other plant process)
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Pall AriaTM Integrated Membrane Systems
• Similar to Custom Systems in terms of capacity and customization.
• Integrates Microfiltration with either Nanofiltration or Reverse Osmosis to meet the water filtrate needs.
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Pall AriaTM Mobile Systems
• Capacities up to 800 gpm
• Turnkey Trailer and Containerized MF systems for:
– Municipal events: boil alerts
– Municipal Expansions and Seasonal Needs
– Temporary and Mobile Industrial Needs
– Natural/Man-made disasters
– Severe weather events
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QUESTIONS?
