September 2004
NSF04/14/EPADWCTR
Environmental Technology
Verification Report
Physical Removal of Microbial
Contamination Agents in Drinking Water
EcoWater Systems, Inc.
Sears Kenmore Ultrafilter 500 Drinking
Water Treatment System
Prepared by
NSF International
Under a Cooperative Agreement with
U.S. Environmental Protection Agency
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THE ENVIRONMENTAL TECHNOLOGY VERIFICATION
PROGRAM -
f /
SERA
ETV
U.S. Environmental Protection Agency
NSF International
ETV Joint Verification Statement
TECHNOLOGY TYPE: POINT-OF-USE DRINKING WATER TREATMENT
SYSTEM
APPLICATION: REMOVAL OF MICROBIAL CONTAMINATION AGENTS
IN DRINKING WATER
PRODUCT NAME: SEARS KENMORE ULTRAFILTER 500
VENDOR: SEARS ROEBUCK, AND COMPANY
MANUFACTURER: ECOWATER SYSTEMS, INCORPORATED
ADDRESS: 1890 WOODLANE DRIVE PHONE: 1-800-808-9899
WOODBURY,MN 55125 FAX: 651-739-5293
EMAIL: INFO@ECOWATER.COM
NSF International (NSF) manages the Drinking Water Systems (DWS) Center under the U.S.
Environmental Protection Agency's (EPA) Environmental Technology Verification (ETV) Program. The
DWS Center recently evaluated the performance of the Sears Kenmore Ultrafilter 500 point-of-use (POU)
reverse osmosis (RO) drinking water treatment system. NSF performed all of the testing activities and
also authored the verification report and this verification statement. The verification report contains a
comprehensive description of the test.
EPA created the ETV Program to facilitate the deployment of innovative or improved environmental
technologies through performance verification and dissemination of information. The goal of the ETV
Program is to further environmental protection by accelerating the acceptance and use of improved and
more cost-effective technologies. ETV seeks to achieve this goal by providing high-quality, peer-
reviewed data on technology performance to those involved in the design, distribution, permitting,
purchase, and use of environmental technologies.
ETV works in partnership with recognized standards and testing organizations, stakeholder groups
(consisting of buyers, vendor organizations, and permitters), and with the full participation of individual
technology developers. The program evaluates the performance of innovative technologies by developing
test plans that are responsive to the needs of stakeholders, conducting field or laboratory tests (as
appropriate), collecting and analyzing data, and preparing peer-reviewed reports. All evaluations are
conducted in accordance with rigorous quality assurance protocols to ensure that data of known and
adequate quality are generated and that the results are defensible.
NSF 04/14/EPADWCTR The accompanying notice is an integral part of this verification statement. September 2004
VS-i
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ABSTRACT
The Sears Kenmore Ultrafilter 500 RO system was tested for removal of bacteria and viruses at NSF's
Drinking Water Treatment Systems Laboratory. EcoWater Systems submitted ten units for testing, which
were split into two groups of five. One group received 25 days of conditioning prior to challenge testing,
while the second group was tested immediately. Both groups were identically challenged. The challenge
organisms were the bacteriophage viruses fr, MS2, and Phi X 174, and the bacteria Brevundimonas
diminuta and Hydrogenophaga pseudoflava. The test units were challenged at two different inlet
pressures - 40 and 80 pounds per square inch, gauge (psig). The virus challenges were conducted at three
different pH settings (6, 7.5, and 9) to assess whether pH influences the performance of the test units.
The bacteria challenges were conducted only at pH 7.5.
The logio reduction data is shown in Tables 2 through 5. The test units removed all challenge organisms
to less-than-detectible levels in all challenges but the pH 9, 80 psig challenge. The data does not show
whether conditioning, inlet pressure or pH influenced bacteria and virus removal.
TECHNOLOGY DESCRIPTION
The following technology description was provided by the manufacturer and has not been verified.
The Ultrafilter 500 is a three-stage POU drinking water treatment system. In addition to the RO
membrane, the system employs carbon filtration. The first stage of treatment is carbon filtration to
remove chlorine as well as suspended particles such as silt, dirt, and rust. The second stage is the RO
membrane, which removes a wide variety of contaminants. The RO treated water is sent to the storage
tank. When the user opens the faucet, the water leaves the storage tank and travels through a second
carbon filter that removes any remaining tastes and odors before it is dispensed. The Ultrafilter 500 is
designed to produce approximately five gallons of wastewater for every gallon of treated water.
The test units were evaluated without the carbon filters in place to eliminate the possibility that these
filters could temporarily trap a portion of the challenge organisms, causing a positive bias of system
performance.
VERIFICATION TESTING DESCRIPTION
Test Site
The testing site was the Drinking Water Treatment Systems Laboratory at NSF in Ann Arbor, Michigan.
A description of the test apparatus can be found in the test/QA plan and verification report. The testing
was conducted in January through March of 2004.
Methods and Procedures
The testing methods and procedures are detailed in the Test/QA Plan for Verification Testing of the Sears
Kenmore Ultrafilter 500 Point-of-Use Drinking Water Treatment System for Removal of Microbial
Contamination Agents. Ten Ultrafilter 500 systems were tested for bacteria and virus removal
performance using the bacteriophage viruses fr, MS2, and Phi X 174, and the bacteria B. diminuta and H.
pseudoflava. The challenge organisms were chosen because they are smaller than most other viruses and
bacteria, and so provide a conservative estimate of performance.
The test units were randomly split into two groups of five. One group was conditioned for 25 days by
operating the units daily using the test water without challenge organisms. The second group was
NSF 04/14/EPADWCTR The accompanying notice is an integral part of this verification statement. September 2004
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challenged without receiving the 25-day conditioning period. The test units were challenged at both 40
and 80 psig inlet pressure. The test water for the bacteria challenges was set to pH 7.5 ± 0.5, while the
virus challenges were conducted at pH 6.0 ± 0.5, 7.5 ± 0.5, and 9.0 ± 0.5. The challenge schedule is
shown in Table 1. The different challenge conditions were intended to evaluate whether inlet pressure or
pH influenced bacteria and virus removal. However, the test water chemistry gave it little buffering
capacity, which made it difficult to keep the pH below 6.5 for the pH 6.0 virus challenges. As a result,
the pH was above 6.5 for three of the four pH 6.0 virus challenges.
Table 1. Challenge Schedule
Day Surrogate Challenge pH Inlet Pressure (psig)
1
2
3
4
5
6
7
8
9
10
H. pseudoflava
H. pseudoflava
B. diminuta
B. diminuta
All Viruses
All Viruses
All Viruses
All Viruses
All Viruses
All Viruses
7.5±0.5
7.5±0.5
7.5±0.5
7.5±0.5
*6.0±0.5
*6.0±0.5
7.5±0.5
7.5±0.5
9.0 ±0.5
9.0 ±0.5
40 ±3
80 ±3
40 ±3
80 ±3
40 ±3
80 ±3
40 ±3
80 ±3
40 ±3
80 ±3
*actual pH ranged from 6.7 - 6.9 in three of four days.
On each challenge day, the test units were operated for one tank-fill period (approximately two hours).
The end of this period was evident through engagement of each system's automatic shutoff mechanism,
which causes the flow of reject water to cease. Influent water samples were collected at the beginning
and end of each challenge period. After each test unit ceased operation, the entire contents of the product
water storage tank were emptied into a sterile container, and a subsample was collected for
microbiological analysis. All samples were enumerated in triplicate. Following each challenge period,
the test units were flushed by operating them for one tank-fill period using the test water without
challenge organisms.
VERIFICATION OF PERFORMANCE
Tables 2 and 3 show the bacteria reduction data for the unconditioned units and conditioned units,
respectively. In all challenges for both sets of test units, the bacteria were removed to less than detectible
levels (< 1 CFU/lOOmL). The predominance of non-detectable results does not allow any evaluation of
whether conditioning, inlet pressure or pH influenced the bacteria reduction performance of the RO
membranes.
Tables 4 and 5 show the virus reduction data for the unconditioned units and conditioned units,
respectively. In all challenges but the pH 9, 80 psig challenge, both sets of test units removed all three
viruses to less than detectible levels (< 1 PFU/mL). The maximum mean effluent count for the pH 9, 80
psig challenges was 11 PFU/mL, which corresponds to the 3.0 logic reduction of fr for unconditioned unit
3. As with the bacteria, the predominance of non-detectable results does not allow an evaluation of the
effect of conditioning, inlet pressure, or pH on RO membrane performance. Complete descriptions of the
verification testing results are included in the verification report.
NSF 04/14/EPADWCTR The accompanying notice is an integral part of this verification statement. September 2004
VS-iii
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pH
Table 2. Bacteria Log Reduction Data for Unconditioned Units
Log10
Pressure Challenge Influent Log10 Reduction
(psig) Organisms Challenge Unit 1 Unit 2 Unit 3 Unit 4 Unit 5
7.5 40
H. pseudoflava
B. diminuta
6.6 All effluents non-detect
6.4 Log reductions equal to influents
7.5 80 H. pseudoflava 6.0 All effluents non-detect
B. diminuta 6.6 Log reductions equal to influents
Table 3. Bacteria Log Reduction Data for Conditioned Units
Log10
Pressure Challenge Influent Log10 Reduction
pH (psig) Organisms Challenge Unit 1 Unit 2 Unit 3 Unit 4 Unit 5
7.5
40
H. pseudoflava
B diminuta
6.6 All effluents non-detect
1 1 Log reductions equal to influents
7.5
80
H. pseudoflava
B. diminuta
6.0
6.8
All effluents non-detect
L°g reductions equal to influents
Table 4. Virus Logio Reduction Data for Unconditioned Units
Challenge Conditions Log10 Reduction
Target Measured Pressure Challenge Log10 Influent
pH pH (psig) Organisms Challenge Unit 1 Unit 2 Unit 3 Unit 4 Unit 5
6.0 + 0.5 6.86
40
fr
MS2
Phi X 174
5'°
4.8
4.5
All effluents non-detect
Log reductions equal to influents
fr
54
6.0 + 0.5
8n
80
All effluents non-detect
Log reductions equal to influents
7.5 + 0.5 7.69
.
40
fr
, ,-,
MS2
Phi X 174
43
.'
5.0
5.3
All effluents non-detect
T ... i ,. « ^
Log reductions equal to influents
7.5 + 0.5 7.91
80
,'
4.9
All effluents non-detect
Log reductions equal to influents
9.0 + 0.5 8.71
,n
40
r\
5.1
All effluents non-detect
Log reductions equal to influents
fr 4.1 3.8 3.6 3.0 4.1 4.1
9.0 + 0.5 8.67 80 MS2 3.9 3.9 3.6 2.9 3.9 3.9
Phi X174 3.7 3.7 3.7 3.7 3.7 3.7
NSF 04/14/EPADWCTR
The accompanying notice is an integral part of this verification statement. September 2004
VS-iv
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Table 5. Virus Logio Reduction Data for Conditioned Units
Challenge Conditions Log10 Reduction
Target Measured Pressure Challenge Logio Influent
pH pH (psig) Organisms Challenge Unit 1 Unit 2 Unit 3 Unit 4 Unit 5
6.0 + 0.5 6.48
40
fr
MS2
Phi XI74
4.8
4.5
3.8
All effluents non-detect
Log reductions equal to influents
6.0 + 0.5 6.69
80
fr
MS2
Phi XI74
4.5
4.4
4.2
All effluents non-detect
Log reductions equal to influents
7.5 + 0.5
7.5 + 0.5
9.0 + 0.5
7.45
7.56
8.73
40
80
40
fr
MS2
Phi XI 74
fr
MS2
Phi XI 74
fr
MS2
Phi XI 74
5.3
5.0
4.3
4.9
4.7
3.9
5.6
5.4
3.8
All effluents non-detect
Log reductions equal to influents
All effluents non-detect
Log reductions equal to influents
All effluents non-detect
Log reductions equal to influents
9.0 + 0.5 8.73
fr
MS2
Phi X 174
5.1
4.8
4.5
5.1
4.5
4.5
4.6
4.3
4.5
5.1
4.8
4.5
5.1
4.8
4.5
5.1
4.5
4.5
Quality Assurance/Quality Control (QA/QC)
NSF provided technical and quality assurance oversight of the verification testing as described in the
verification report, including an audit of nearly 100% of the data. NSF personnel also conducted a
technical systems audit during testing to ensure the testing was in compliance with the test plan. A
complete description of the QA/QC procedures is provided in the verification report.
Orginal signed by
E. Timothy Oppelt
09/20/04
Orginal signed by
Gordon Bellen
09/23/04
E. Timothy Oppelt Date
Director
National Homeland Security Research Center
United States Environmental Protection
Agency
Gordon Bellen
Vice President
Research
NSF International
Date
NOTICE: Verifications are based on an evaluation of technology performance under specific,
predetermined criteria and the appropriate quality assurance procedures. EPA and NSF make no
expressed or implied warranties as to the performance of the technology and do not certify that a
technology will always operate as verified. The end-user is solely responsible for complying with
any and all applicable federal, state, and local requirements. Mention of corporate names, trade
names, or commercial products does not constitute endorsement or recommendation for use of
specific products. This report is not an NSF Certification of the specific product mentioned
herein.
NSF 04/14/EPADWCTR
The accompanying notice is an integral part of this verification statement. September 2004
VS-v
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Availability of Supporting Documents
Copies of the test protocol, the verification statement, and the verification report (NSF
report # NSF 04/14/EPADWCTR) are available from the following sources:
(NOTE: Appendices are not included in the verification report. Appendices are available
from NSF upon request.)
1. ETV Drinking Water Systems Center Manager (order hard copy)
NSF International
P.O. Box 130140
Ann Arbor, Michigan 48113-0140
2. NSF web site: http://www.nsf. org/etv (electronic copy)
3. EPA web site: http://www. epa.gov/etv (electronic copy
NSF 04/14/EPADWCTR The accompanying notice is an integral part of this verification statement. September 2004
VS-vi
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September 2004
Environmental Technology Verification Report
Removal of Microbial Contamination Agents in Drinking Water
EcoWater Systems Incorporated
Sears Kenmore Ultrafilter 500 Drinking Water Treatment System
Prepared by:
NSF International
Ann Arbor, Michigan 48105
Under a cooperative agreement with the U.S. Environmental Protection Agency
Jeffrey Q. Adams, Project Officer
National Risk Management Research Laboratory
U.S. Environmental Protection Agency
Cincinnati, Ohio 45268
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Notice
The U.S. Environmental Protection Agency (EPA), through its Office of Research and
Development, has financially supported and collaborated with NSF International (NSF) under
Cooperative Agreement No. R-82833301. This verification effort was supported by the Drinking
Water Systems (DWS) Center, operating under the Environmental Technology Verification
(ETV) Program. This document has been peer-reviewed, reviewed by NSF and EPA, and
recommended for public release.
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Foreword
The U.S. Environmental Protection Agency (EPA) is charged by Congress with
protecting the Nation's land, air, and water resources. Under a mandate of national
environmental laws, the Agency strives to formulate and implement actions leading to a
compatible balance between human activities and the ability of natural systems to support and
nurture life. To meet this mandate, EPA's research program is providing data and technical
support for solving environmental problems today and building a science knowledge base
necessary to manage our ecological resources wisely, understand how pollutants affect our
health, and prevent or reduce environmental risks in the future.
The National Risk Management Research Laboratory (NRMRL) is the Agency's center
for investigation of technological and management approaches for preventing and reducing risks
from pollution that threaten human health and the environment. The focus of the Laboratory's
research program is on methods and their cost-effectiveness for prevention and control of
pollution to air, land, water, and subsurface resources; protection of water quality in public water
systems; remediation of contaminated sites, sediments and ground water; prevention and control
of indoor air pollution; and restoration of ecosystems. NRMRL collaborates with both public
and private sector partners to foster technologies that reduce the cost of compliance and to
anticipate emerging problems. NRMRL's research provides solutions to environmental problems
by: developing and promoting technologies that protect and improve the environment; advancing
scientific and engineering information to support regulatory and policy decisions; and providing
the technical support and information transfer to ensure implementation of environmental
regulations and strategies at the national, state, and community levels.
This publication has been produced as part of the Laboratory's strategic long-term
research plan. It is published and made available by EPA's Office of Research and Development
to assist the user community and to link researchers with their clients.
in
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Table of Contents
Verification Statement VS-i
Title Page i
Notice ii
Foreword iii
Table of Contents iv
List of Tables vi
List of Figures vi
Abbreviations and Acronyms vii
Acknowlegements viii
Chapter 1 Introduction 1
1.1 Environmental Technology Verification (ETV) Program Purpose and Operation 1
1.2 Development of Test/Quality Assurance (QA) Plan 1
1.2.1 Bacteria and Virus Surrogates 2
1.2.2 Inlet Pressure 3
1.2.3 Long-Term Conditioning 3
1.3 Testing Participants and Responsibilities 3
1.3.1 NSF International 4
1.3.2 EcoWater Systems Incorporated 4
1.3.3 U.S. Environmental Protection Agency 4
Chapter 2 Equipment Description 6
2.1 RO Membrane Operation 6
2.2 Equipment Capabilities 6
2.3 System Components 6
2.4 System Operation 8
2.5 Equipment Operation Limitations 8
2.6 Operation and Maintenance Requirements 8
Chapter 3 Methods and Procedures 9
3.1 Test Equipment 9
3.1.1 Equipment Selection 9
3.1.2 Test Unit Configuration 9
3.2 Verification Test Procedure 9
3.2.1 Test Rig 9
3.2.2 Test Rig Sanitization 9
3.2.3 Test Water 10
3.2.3.1 Base Water 10
3.2.3.2 Bacteria and Virus Challenges 11
3.2.4 Test Unit Operation 12
3.2.4.1 Test Unit Installation 12
3.2.4.2 TDS Reduction System Check 12
3.2.4.3 Long-Term Conditioning 12
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3.2.4.4 Challenge Testing 13
3.3 Analytical Methods 14
3.3.1 Water Quality Analytical Methods 14
3.3.2 Microbiology Analytical Methods 14
3.3.2.1 Sample Processing, and Enumeration of Viruses 14
3.3.2.2 Bacteria Cultivation 14
3.3.2.3 Preparation of Bacteria Challenge Suspensions 15
3.3.2.4 Sample Processing and Enumeration of Bacteria 15
Chapter 4 Results and Discussion 16
4.1 IDS Reduction 16
4.2 Bacteria Reduction 16
4.3 Virus Reduction 17
Chapters QA/QC 19
5.1 Data Review 19
5.2 Test Procedure QA/QC 19
5.3 Water Chemistry Analytical Methods QA/QC 19
5.4 Microbiology Laboratory QA/QC 19
5.4.1 Growth Media 19
5.4.2 Bacteria Cell Size 20
5.4.3 Sample Processing and Enumeration 20
5.5 Sample Handling 20
5.6 Documentation 20
5.7 Data Quality Indicators 20
5.7.1 Representativeness 21
5.7.2 Accuracy 21
5.7.3 Precision 21
5.7.4 Statistical Uncertainty 22
5.7.5 Completeness 22
5.7.5.1 Completeness Measurements 22
5.8 Measurements Outside of the Test/QA Plan Specifications 23
5.8.1 Total Chlorine 23
5.8.2 pH 23
Chapter 6 References 24
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Appendices
Appendix A Virus and Bacteria Reduction Data
Appendix B QA/QC Measurements
Appendix C NSF Drinking Water Treatment Systems Laboratory and Chemistry Laboratory
Bench Sheets
Appendix D Microbiology Laboratory Bench Sheets
Appendix E NSF Testing Laboratory Reports
List of Tables
Table 1-1. Virus and Host ATCC Designations 2
Table 3-1. Challenge Schedule 13
Table 4-1. Short-Term TDS Reduction Test Results 16
Table 4-2. Bacteria Log Reduction Data for Unconditioned Units 17
Table 4-3. Bacteria Log Reduction Data for Conditioned Units 17
Table 4-4. Virus Log Reduction Data for Unconditioned Units 18
Table 4-5. Virus Log Reduction Data for Conditioned Units 18
Table 5-1. Completeness Requirements 22
List of Figures
Figure 2-1. Photograph of the Ultrafilter 500 7
Figure 2-2. Schematic Diagram of the Ultrafilter 500 7
Figure 3-1. Schematic Diagram of Test Rig 10
Figure 3-2. Test Units Installed on Test Rig 11
VI
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Abbreviations and Acronyms
ANSI
ASTM
ATCC
°C
CPU
cm
DWS
EPA
ETV
°F
L
mg
mL
nm
NRMRL
NSF
PBDW
PFU
POU
psig
QA
QC
QA/QC
RO
SOP
IDS
ISA
TSB
Mg
Ml
um
umho
US
American National Standards Institute
American Society of Testing Materials
American Type Culture Collection
Degrees Celsius
Colony Forming Unit
Centimeter
Drinking Water Systems
U. S. Environmental Protection Agency
Environmental Technology Verification
Degrees Fahrenheit
Liter
Milligram
Milliliter
Nanometer
National Risk Management Research Laboratory
NSF International (formerly known as National Sanitation Foundation)
Phosphate-Buffered Dilution Water
Plaque Forming Unit
Point-of-Use
Pounds per Square Inch Gauge
Quality Assurance
Quality Control
Quality Assurance/Quality Control
Reverse Osmosis
Standard Operating Procedure
Total Dissolved Solids
Tryptic Soy Agar
Tryptic Soy Broth
Microgram
Microliter
Micrometer
Micromho
MicroSieman
vn
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Acknowledgments
NSF International was responsible for all elements in the testing sequence, including collection
of samples, calibration and verification of instruments, data collection and analysis, data
management, data interpretation and the preparation of this report.
The Manufacturer of the Equipment was:
EcoWater Systems Incorporated
1890 Woodlane Drive
Woodbury, MN 55125
NSF wishes to thank the members of the expert technical panel for their assistance with
development of the test plan.
vin
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Chapter 1
Introduction
1.1 Environmental Technology Verification (ETV) Program Purpose and Operation
The U.S. Environmental Protection Agency (EPA) has created the ETV Program to facilitate the
deployment of innovative or improved environmental technologies through performance
verification and dissemination of information. The goal of the ETV Program is to further
environmental protection by accelerating the acceptance and use of improved and more cost-
effective technologies. ETV seeks to achieve this goal by providing high-quality, peer-reviewed
data on technology performance to those involved in the design, distribution, permitting,
purchase, and use of environmental technologies.
ETV works in partnership with recognized standards and testing organizations; with stakeholder
groups consisting of buyers, vendor organizations, and permitters; and with the full participation
of individual technology developers. The program evaluates the performance of innovative
technologies by developing test plans that are responsive to the needs of stakeholders; by
conducting field or laboratory testing, collecting and analyzing data; and by preparing peer-
reviewed reports. All evaluations are conducted in accordance with rigorous quality assurance
protocols to ensure that data of known and adequate quality are generated and that the results are
defensible.
The EPA has partnered with NSF International (NSF) under the ETV Drinking Water Systems
(DWS) Center to verify performance of drinking water treatment systems that benefit the public
and small communities. It is important to note that verification of the equipment does not mean
the equipment is "certified" by NSF or "accepted" by EPA. Rather, it recognizes that the
performance of the equipment has been determined and verified by these organizations under
conditions specified in ETV protocols and test plans.
1.2 Development of Test/Quality Assurance (QA) Plan
As part of the national Homeland Security effort, NSF has developed a test/QA plan under the
EPA ETV Program for evaluating point-of-use (POU) reverse osmosis (RO) drinking water
treatment systems for removal of biological contamination agents. This test/QA plan uses
surrogate bacteria and viruses in place of testing with the actual agents of concern. The test
organisms serve as surrogates not only for bacteria and viruses, but also protozoa, such as
Cryptosporidium oocysts. Please note that this test plan does not cover chemical agents derived
from microorganisms, such as ricin or botulism toxin.
To assist in this endeavor, NSF assembled an expert technical panel, which recommended the
experimental design and surrogate choices prior to the initiation of testing. Panel members
included experts from the EPA, United States Army, and United States Centers for Disease
Control and Prevention, Division of Parasitic Diseases, as well as a water utility microbiologist,
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a university professor, and an independent consultant in the POU drinking water treatment
systems industry.
By participating in this ETV, vendors obtain EPA and NSF verified third-party test data
indicating potential user protection against intentional biological contamination of potable water.
POU RO systems are not typically marketed as water purifiers that remove bacteria and viruses
from drinking water, but they may still remove significant numbers of the microorganisms, thus
offering the user a significant level of protection. The verifications serve to notify the public of
the possible level of protection against biological contamination agents afforded to them by the
use of verified systems.
The test/QA plan called for testing ten Ultrafilter 500 units with a standard test water set to pH 6,
7.5, and 9, containing bacterial or viral surrogates. The systems were also challenged at both 40
and 80 pounds per square inch gauge (psig). The test units were subjected to challenge scenarios
that were unique combinations of the challenge organisms, pH, and inlet water pressure. Five
units were challenged immediately after completion of the manufacturer's installation and
conditioning instructions, while the other five underwent a 25-day conditioning period prior to
being challenged with the surrogates.
1.2.1 Bacteria and Virus Surrogates
The expert technical panel recommended that NSF and the EPA use the bacteria Brevundimonas
diminuta (American Type Culture Collection (ATCC) strain 19146, formerly Pseudomonas
diminuta)., and Hydrogenophaga pseudoflava (ATCC strain 33668) as surrogates for bacterial
agents. These surrogates were chosen based on their small sizes, as the smallest identified
bacterium of concern can be as small as 0.2 |j,m in diameter. H. pseudoflava has a minimum
diameter of 0.1 to 0.2 |j,m, while B. diminuta has a minimum diameter of 0.2 to 0.3 |j,m (please
note that these minimum diameters were not obtained during this study. See section 5.4.2 for
discussion). B. diminuta is the accepted bacteria of choice for testing filters and membranes
designed to remove bacteria. It is used in the American Society of Testing Materials (ASTM)
"Standard Test Method for Retention Characteristics of 0.2-um Membrane Filters Used in
Routine Filtration Procedures for the Evaluation of Microbiological Water Quality" (2001).
The virus surrogates were the bacteriophages MS2, Phi X 174, and fr. The ATCC designation
and hostE1. coli strain for each virus is given Table 1-1.
Table 1-1. Virus and Host ATCC Designations
Virus ATCC Designation Host Bacteria ATCC Strain
MS2 ATCC 15597-Bl E. coli ATCC 15597
Phi X 174 ATCC 13706-B1 E. coli ATCC 13706
fr ATCC 15767-Bl E. coli ATCC 19853
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The expert technical panel recommended these viruses based on their small sizes and isoelectric
points. The isoelectric point is the pH at which the virus surface is neutrally charged. MS2 is 24
nm in diameter with an isoelectric point at pH 3.9, Phi X 174 is 27 nm in diameter with an
isoelectric point at pH 6.6, and fr is 19 nm in diameter with an isoelectric point at pH 8.9. With
varying isoelectric points, the viruses have different surface charges, or different strengths of
negative or positive charge, depending on the pH. In solutions above the isoelectric point, the
virus is negatively charged. Below the isoelectric point, the virus is positively charged. Using
different pH settings for the virus challenges allowed an evaluation of whether electrostatic
forces enhance virus retention in mechanical filtration scenarios. The pH 6 and 9 settings were
chosen because they just are beyond the upper and lower boundaries for allowable pH in the
EPA National Secondary Drinking Water Regulations. The pH 7.5 setting was chosen because it
is the midpoint between the boundaries.
The bacteria reduction challenges ware performed only at pH 7.5, because the expert panel
believed that bacteria cell size and mass are too large for electrostatic interactions to play a
significant role.
1.2.2 Inlet Pressure
The bacteria and virus challenge tests were performed at dynamic inlet pressures of both 40 and
80 psig to evaluate whether inlet pressure affects microorganism rejection by RO membranes.
Forty psig is a worse case scenario for ionic rejection mechanisms, while 80 psig represents a
poorer mechanical filtration scenario. In a traditional mechanical filtration scenario, the higher
pressure could push suspended particles further into, and perhaps all the way through, the
filtration media, and it could also distort seals to the point that they leak. However, this may or
may not be the case with RO membranes, since they operate by a different principle.
1.2.3 Long-Term Conditioning
The expert technical panel was presented with anecdotal evidence that RO membrane
performance could be erratic for approximately the first month of operation, so they
recommended that NSF split the test units into two groups, one group to be tested immediately
after installation and completion of the manufacturer's conditioning instructions (hereafter
referred to as "unconditioned units"), and a second group to be tested after a 25 working day
conditioning period (hereafter referred to as "conditioned units").
1.3 Testing Participants and Responsibilities
The ETV testing of the Sears Kenmore Ultrafilter 500 was a cooperative effort between the
following participants:
NSF
EcoWater Systems, Inc.
EPA
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The following is a brief description of each of the ETV participants and their roles and
responsibilities.
1.3.1 NSF International
NSF is a not-for-profit organization dedicated to public health and safety, and to protection of the
environment. Founded in 1946 and located in Ann Arbor, Michigan, NSF has been instrumental
in the development of consensus standards for the protection of public health and the
environment. The EPA partnered with NSF to verify the performance of drinking water
treatment systems through the EPA's ETV Program.
NSF performed all verification testing activities at its Ann Arbor location. NSF prepared the
test/QA plan, performed all testing, managed, evaluated, interpreted, and reported on the data
generated by the testing, and reported on the performance of the technology.
Contact Information:
NSF International
789 N. Dixboro Road
Ann Arbor, MI 48105
Phone: 734-769-8010
Fax: 734-769-0109
Contact: Bruce Bartley, Project Manager
Email: bartley@nsf.org
1.3.2 EcoWater Systems Incorporated
The verified system is manufactured by EcoWater Systems, a manufacturer of residential and
commercial water treatment products.
The manufacturer was responsible for supplying the RO systems in accordance with the
equipment selection criteria given in section 3.1.1, and for providing logistical and technical
support as needed.
Contact Information:
EcoWater Systems Incorporated
1890 Woodland Drive
Woodbury, MN 55125
Contact Person: Ann Baumann
Phone: 1-800-808-9899
1.3.3 U.S. Environmental Protection Agency
The EPA, through its Office of Research and Development, has financially supported and
collaborated with NSF under Cooperative Agreement No. R82833301. This verification effort
-------
was supported by the DWS Center operating under the ETV Program. This document has been
peer-reviewed, reviewed by the EPA, and recommended for public release.
-------
Chapter 2
Equipment Description
2.1 RO Membrane Operation
Membrane technologies are among the most versatile water treatment processes with regard to
their ability to effectively remove the widest variety of contaminants at the lowest costs. Reverse
osmosis membranes operate by the principal of cross-flow filtration. In this process, the influent
water flows over and parallel to the filter medium and exits the system as reject water. Under
pressure, a portion of the water diffuses through the membrane becoming "permeate".
Membrane pore sizes are small enough to reject bacteria and viruses, but they may still pass
through imperfections h the membrane, or go around the membrane due to microscopic seal
leaks.
2.2 Equipment Capabilities
The Ultrafilter 500 is certified by NSF International to NSF/ANSI Standard 58 - Reverse
Osmosis Drinking Water Treatment Systems. It has a certified production rate of 12 gallons per
day, and produces five gallons of wastewater per gallon of treated water. These measurements
are based on system operation at 50 psig inlet pressure, a water temperature of 77 °F, and a total
dissolved solids (TDS) level of 750 mg/L. The amount and quality of treated water produced
varies depending on the inlet pressure, water temperature, and level of TDS. These
measurements were not subject to verification during this study.
2.3 System Components
The Ultrafilter 500 is a three-stage treatment system. Incoming water first passes through a
carbon filter designed to remove chlorine and particulate matter such as dirt, silt, and rust. The
second stage of treatment is the reverse osmosis membrane, which reduces a wide variety of
contaminants. The permeate water is sent to a 2.3-gallon maximum capacity storage tank. Upon
leaving the storage tank, the water passes through a second carbon filter to remove any
remaining tastes and odors, then out through the faucet. Figure 2-1 is a photograph of the
system, and Figure 2-2 is a schematic diagram of the system showing the path of water flow.
Please note that this description, and the system operation description in section 2.4 are given for
informational purposes only. This information was not subject to verification.
-------
Figure 2-1. Photograph of the Ultrafilter 500
PRODUCT
WATEfl
FAUCET
air gap
gravity
drain
Figure 2-2. Schematic Diagram of the Ultrafilter 500
P...UF ^ PRODUCT WATER
RED
drain flow
control
AUTOMATIC
SHUTOFF
WATER GREEN
check
vaive
4
YELLOW
t
t
*
t
*
*
RO
PREFILTER MEMBRANE POSTFILTER
PRODUCT
WATER
STORAGE
-------
2.4 System Operation
When the flow of water into the system is started, treated water will be continually produced
until the storage tank is nearly full. At that time, the water pressure in the tank causes an
automatic shut-off device to activate, stopping the flow of water through the system. After
approximately ten percent of the treated water is dispensed from the storage tank, the shut-off
device deactivates, allowing water to again flow into the system until the storage tank is nearly
full. The operational storage tank capacity will vary slightly from unit to unit, and is also
affected by the inlet water pressure, but is approximately two gallons under normal use
conditions.
The Ultrafilter 500 has a combination volume and TDS level meter that measures the volume of
treated water produced and the amount of TDS in the treated water. The faucet has a three
colored indicator light to tell the user when to replace the carbon filters and RO membrane.
Under normal operation, the indicator light is green. After six months have passed, or 750
gallons of treated water has been produced, the light changes to amber, indicating that the carbon
filters need to be replaced. The light turns red when the TDS level in the treated water has risen
to above a certain level. At this point the RO membrane should be replaced. The user must reset
the meter each time any treatment elements are replaced.
2.5 Equipment Operation Limitations
EcoWater Systems gives the following limitations for the drinking water to be treated by the
system:
temperature of 40 - 10 0 °F;
pressure of 40 - 100 psig;
pHof4-10;
maximum TDS level of 2,000 mg/L;
maximum water hardness of 10 grains per gallon (1 grain per gallon equals 17.1 mg/L of
TDS, expressed as calcium carbonate equivalent);
no detectible iron, manganese, or hydrogen sulfide; and
maximum chlorine level of 2 mg/L.
2.6 Operation and Maintenance Requirements
The following are the operation and maintenance requirements specified in the product owner's
manual:
Replacement of the carbon filters when indicated by the meter (every six months or 750
gallons);
Replacement of the RO membrane cartridge when indicated by the meter; and
Sanitization of the system when the carbon filters or RO membrane are replaced
(instructions included in the owner's manual.)
-------
Chapter 3
Methods and Procedures
3.1 Test Equipment
3.1.1 Equipment Selection
Equipment selection criteria were developed to ensure that the test units were representative of
product variability. The test/QA plan called for EcoWater Systems to supply ten units from three
different production runs, with RO membranes from three different lots, if possible. At the time
of testing, EcoWater Systems had units and RO membranes from only one lot in inventory, so
the test units were randomly split into two groups of five.
3.1.2 Test Unit Configuration
The Ultrafilter 500 was tested with only the RO membrane in place. The carbon filters do not
have pore sizes small enough to remove bacteria or viruses, but they could temporarily retain
significant numbers of the organisms through electrostatic interactions, giving a positive bias to
the performance data. Empty filter cartridges were used in place of the carbon filters. Otherwise
the systems were operated as sold to the consumer.
3.2 Verification Test Procedure
3.2.1 Test Rig
Each group of five test units was plumbed to a single test station. The test station used a 500-
gallon polyethylene tank to hold the influent challenge water. See Figure 3-1 for a schematic
diagram of the test rig. Please note that the units of each group of five were attached to the rig,
such that all were plumbed to the same influent feed line. Figure 3-2 shows one group of the test
units installed on the test rig.
3.2.2 Test Rig Sanitization
The test apparatus was sanitized with a sanitization agent prior to the beginning of each test to
keep the heterotrophic bacteria population to a minimum. After sanitization, the test apparatus
was flushed until a less-than-detectable concentration of sanitizing agent was present.
-------
Figure 3-1. Schematic Diagram of Test Rig
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ater supply
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sampling points
3.2.3 Test Water
3.2.3.1 Base Water
Ann Arbor, Michigan municipal drinking water was deionized to make the base water for the
tests. The base water had the following constraints:
Conductivity < 2 uS/cm at 25 °C;
TOC < 100 ug/L; and
Heterotrophic bacteria plate count < 100 colony forming units (CFU)/mL.
The base water was then adjusted to meet the following characteristics:
Total chlorine = 0.05 mg/L;
Addition of sodium bicarbonate to achieve an alkalinity (expressed as calcium carbonate)
of 100 ± 5 mg/L prior to pH adjustment;
pH adjustment with hydrochloric acid or sodium hydroxide to reach a value of 6.0 ±0.5*,
7.5 ± 0.5, or 9.0 ± 0.5 as required by challenge protocol; and
Temperature of 20 ± 2.5 ° C.
*Note that the lab technicians experienced difficulty maintaining the pH below 6.5. As a result, the challenge water
pH for three of the four pH 6.0 challenges was between 6.5 and 7.0. See Section 5.8.2 for more discussion.
10
-------
The test water was made daily in 200-gallon volumes. In addition to the above characteristics,
total hardness, IDS, and turbidity were measured daily.
Figure 3-2. Test Units Installed on Test Rig
3.2.3.2 Bacteria and Virus Challenges
The viruses were purchased from Biological Consulting Services of North Florida, and the
bacteria from ATCC. The viruses were purchased in adequate volumes so that the suspensions
received were added directly to the test water. The bacteria were cultivated at NSF to obtain the
challenge suspensions. Section 3.3.2.3 describes the method used to create the bacteria
challenges.
The targeted influent challenge concentrations for the bacteria were IxlO5 CPU of bacteria per
100 milliliters, or greater. This target was exceeded for the B. diminuta challenges, but not for
the H. pseudoflava challenges during the first attempt. The influent sample analyses from the H.
pseudoflava challenges for both the unconditioned and conditioned groups were less than 1x105
11
-------
CFU/lOOmL. This may have been due to the use of a bad batch of growth media, or a non-viable
or stressed challenge suspension. The H. pseudoflava challenges were conducted again after all
other challenges were complete. The influent CPU counts for the second challenges were above
the IxlO5 CFU/lOOmL target.
The target influent concentration for the viruses was IxlO4 plaque forming units (PFU) of virus
per milliliter, or greater. Phi X 174 is more difficult to cultivate, and so was sometimes supplied
at lower concentrations than the other viruses. As a result, four of the virus challenge influents
did not meet the target concentration for Phi X 174. Assuring Phi X 174 influents greater than
IxlO4 PFU/mL would have been prohibitively expensive, due to the high cost of the virus per
liter.
See Appendix A for all influent challenge levels.
The test units were challenged with each bacteria separately, but all three viruses were mixed
together for each virus challenge. After addition of the challenge organism to the base test water,
the resultant challenge water was mixed for a minimum of 30 minutes using a recirculation pump
prior to beginning the test.
3.2.4 Test Unit Operation
3.2.4.1 Test Unit Installation
All test units were installed on the test rigs by a laboratory technician. Immediately after
installation, the units were conditioned according to the vendor's instructions using the base test
water at pH 7.5 ± 0.5. The conditioning instructions call for operation for six tank-filling
periods. At the end of the conditioning procedure, an effluent sample was collected from each
unit as a negative control and analyzed for the challenge organisms.
3.2.4.2 TDS Reduction System Check
After completion of the vendor's conditioning procedure, the test units underwent a one-day
TDS reduction test using the test protocol in NSF/ANSI Standard 58. The Standard 58 test
protocol was modified so that the units were operated continuously for one tank-fill period.
Product water samples were then collected from each storage tank and analyzed for TDS. This
test ensured that the products undergoing verification testing were representative of the expected
performance of the system, and that there were no membrane integrity or membrane seal
problems.
3.2.4.3 Long-Term Conditioning
After the TDS reduction system check test, the five units receiving long-term conditioning were
operated using the test water without surrogate organisms for a period of 25 working days prior
to challenge testing. On each day the units were operated continuously at a dynamic inlet
pressure of 80 ± 3 psig for one tank-fill period. The units then sat idle overnight under pressure,
and the tanks were emptied the next morning prior to resumption of unit operation.
12
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3.2.4.4 Challenge Testing
Following the conditioning period, the conditioned units were challenged according to the
schedule in Table 3-1. Prior to the start of challenge testing for this group, the test rig was
sanitized again as described in section 3.2.2. The test units were taken off-line to prevent
sanitizer from entering them, and the test rig was flushed free of sanitizer before they were
reconnected to the rig.
Table 3-1. Challenge Schedule
Day Surrogate Challenge pH Inlet Pressure (psig)
1
2
3
4
5
6
7
8
9
10
H. pseudoflava
H. pseudoflava
B. diminuta
B. diminuta
All Viruses
All Viruses
All Viruses
All Viruses
All Viruses
All Viruses
7.5 ±0.5
7.5 ±0.5
7.5 ±0.5
7.5 ±0.5
6.0 ±0.5
6.0 ±0.5
7.5 ±0.5
7.5 ±0.5
9.0 ±0.5
9.0 ±0.5
40 ±3
80 ±3
40 ±3
80 ±3
40 ±3
80 ±3
40 ±3
80 ±3
40 ±3
80 ±3
Challenge testing for the unconditioned units began the day after the TDS system check test.
Testing for this group also followed the schedule in Table 3-1.
At the end of the workday before each challenge, the base test water was prepared as described
in section 3.2.3.1. The morning of the challenge, the pH was checked and adjusted, if necessary,
and the bacteria or viruses were added as described in section 3.2.3.2.
The dynamic inlet water pressure for operation was set at either 40 ± 3 or 80 ± 3 psig according
to the challenge schedule.
An influent sample was collected each day at the time test unit operation started. Each test unit
was then operated continuously for one tank-fill period. At 40 psig, approximately 1.5 gallons of
treated water were produced, while at 80 psig, approximately 2 gallons were produced. The time
of operation was approximately two hours at both pressures.
After each unit shut off, its storage tank was emptied into a sterile container, and a sub-sample
was collected for challenge organism enumeration. The sub-sample volumes were 1.0 L for the
bacteria challenges, and 150 mL for virus challenges. A second influent sample was collected
after all units ceased operation. All samples were collected in sterile polypropylene bottles, and
were enumerated in triplicate.
Following each day's challenge period, the systems were operated for one tank-fill period using
the test water without any test organisms present. This served to flush the systems in-between
13
-------
challenge periods. The units rested overnight under pressure, and the storage tanks were emptied
the next morning prior to initiation of that day's challenge period.
3.3 Analytical Methods
3.3.1 Water Quality Analytical Methods
The following are the analytical methods used during verification testing. All analyses followed
procedures detailed in NSF Standard Operating Procedures (SOPs).
pH - All pH measurements were made with an Orion Model SA 720 meter. The meter
was operated according to the manufacturer's instructions, which are based on Standard
Method 4500-Ff.
Temperature - Water temperature was measured using an Omega model HH11 digital
thermometer.
TDS - TDS for the TDS reduction system check test was measured through conductivity
according to Standard Method 2510 using a Fisher Scientific Traceable Conductivity
Meter.
Total Chlorine - Total chlorine was measured according to Standard Method 4500-C1 G
with a Hach Model DR/2010 spectrophotometer using AccuVac vials.
3.3.2 Microbiology Analytical Methods
3.3.2.1 Sample Processing, and Enumeration of Viruses
The viruses were enumerated using a double agar layer method published in NSF/ANSI Standard
55 - Ultraviolet Microbiological Water Treatment Systems for enumerating MS2. This method
is similar to the double agar layer method in EPA Method 1601.
Four to eighteen hours prior to sample processing, 100 |j,L of the appropriate host E.coli
suspension was pipetted into tubes containing 10 mL of fresh Tryptic Soy Broth (TSB), and
incubated at 35 °C. After incubation, 100 |j,L volumes of the resulting E. coli culture were
transferred to sterile, capped test tubes.
All samples were enumerated in triplicate. All samples were serially diluted for enumeration,
and the effluent samples were also enumerated directly. One milliliter volumes of the sample or
dilution were pipetted into the E. coli suspension test tubes. The tubes were vortexed for a
minimum of 30 seconds to "mate" the bacteria and virus, and then 4 mL of molten, tempered
TSB plus 1% agar was added to each tube. These mixtures were then poured over Tryptic Soy
Agar (TSA) plates, and allowed to solidify. The plates were incubated at 35 °C for 18-24 hours.
Viral plaques were counted using a Quebec Colony Counter.
3.3.2.2 Bacteria Cultivation
The bacteria were purchased from ATCC and rehydrated with nutrient broth. After 48 hours of
incubation at 30 °C, tubes containing 10 mL of TSB were inoculated with 100 |j,L of the nutrient
broth suspension. These tubes were incubated for 48 hours at 30 °C. After this incubation
14
-------
period, 100 |j,L of these suspensions were pipetted into new tubes containing 10 mL of fresh
TSB. These tubes were then also incubated for 48 hours at 30 °C. This process was repeated at
least three times, up to a maximum of 30 times.
3.3.2.3 Preparation of Bacteria Challenge Suspensions
To obtain the challenge suspensions, 1 mL of a 48-hour TSB culture was pipetted onto an
appropriate number of TSA slants. The slants were inoculated at 30 °C for 48 hours. When a
challenge suspension was needed, 5 mL of sterile phosphate-buffered dilution water (PBDW)
was pipetted onto the slants, and the agar surfaces were scraped to suspend the cells. The
overlying water was then pipetted out of the slants into an appropriate volume of PBDW. The
resulting challenge suspension was vortexed for approximately 30 seconds to disperse the cells.
The challenge suspensions were refrigerated and added to the tank of test water within one hour.
Samples of the challenge suspension were collected and enumerated according to the method in
3.3.2.4.
3.3.2.4 Sample Processing and Enumeration of Bacteria
All samples were enumerated in triplicate using a membrane filtration method based on Standard
Method 9215 D. All samples were serially diluted for enumeration with sterile PBDW, and the
effluent samples were also enumerated directly. One-milliliter volumes of either the sample or
dilution were pipetted into sterile vacuum filtration apparatuses, 25 mL of PBDW added, and the
suspension vacuum filtered through sterile 0.1 jam membrane filters. The funnels were then
rinsed three times with approximately 5 mL of PBDW, and the rinse water also suctioned
through the filters. The membrane filters were aseptically removed from the apparatuses and
placed onto R2A agar plates. The plates were incubated at 30 °C for 48 hours. Characteristic B.
diminuta or H. pseudoflava colonies were counted with a Quebec Colony Counter.
15
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Chapter 4
Results and Discussion
4.1 TDS Reduction
The performance data from the TDS reduction system check test described in 3.2.4.2 are
presented in Table 4-1. EcoWater Systems's reported average TDS reduction performance for
the Ultrafilter 500 is 97%, so the units tested are representative of expected membrane
performance.
Table 4-1. Short-Term TDS Reduction Test Results
Unconditioned Units
TDS Percent
(mg/L) Reduction
Influent
Effluents:
Unit 1
Unit 2
Umt3
Unit 4
Umt5
796
64
61
62
63
58
92
92
92
92
93
Conditioned units
TDS Percent
(mg/L) Reduction
Influent
Effluents:
Unit 1
Unit 2
Umt3
Unit 4
Umt5
795
51
44
34
44
20
94
94
96
94
97
4.2 Bacteria Reduction
Presented in Tables 4-2 and 4-3 are the logo reduction data for the bacteria challenge portion of
the verification test. The influent and effluent bacteria count and logo reduction data for each
individual test unit is given in Appendix A. The triplicate influent and effluent counts in
Appendix A were averaged by calculating geometric means. The means were then logo
transformed and logo reduction values were calculated for each test unit. The tables below give
the logo reduction performance data for each pH and inlet pressure combination.
In all challenges for both sets of test units the bacteria were removed to less than detectible levels
(< 1 CFU/lOOmL). The variables of pH and pressure had no discernible impact on the
performance of the test units. There was also no measurable difference in performance between
the unconditioned units and conditioned units.
16
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Table 4-2. Bacteria Log Reduction Data for Unconditioned Units
pH
7.5
7.5
Pressure Challenge
(psig) Organisms
40 H. pseudoflava
B. diminuta
80 H. pseudoflava
B. diminuta
Log10
Influent
Challenge
6.6
6.4
5.9
6.6
Geometric Mean Logio Reduction
Unit 1 Unit 2 Unit 3 Unit 4 Unit 5
6.6
6.4
5.9
6.6
6.6
6.4
5.9
6.6
6.6
6.4
5.9
6.6
6.6
6.4
5.9
6.6
6.6
6.4
5.9
6.6
Table 4-3. Bacteria Log Reduction Data for Conditioned Units
pH
7.5
7.5
Pressure Challenge
(psig) Organisms
40 H. pseudoflava
B. diminuta
80 H. pseudoflava
B. diminuta
Log10
Influent
Challenge
6.6
7.1
5.9
6.8
Geometric Mean Logio Reduction
Unit 1 Unit 2 Unit 3 Unit 4 Unit 5
6.6
7.1
5.9
6.8
6.6
7.1
5.9
6.8
6.6
7.1
5.9
6.8
6.6
7.1
5.9
6.8
6.6
7.1
5.9
6.8
4.3 Virus Reduction
The virus logo reduction data for each challenge scenario are presented in Tables 4-4 and 4-5.
The influent and effluent virus PFU count and logo reduction data for each individual test unit
are given in Appendix A. As was done for the bacteria, the triplicate influent and effluent counts
were averaged by calculating geometric means. The means were then logo transformed and logo
reduction values calculated for each test unit.
In all challenges but the pH 9, 80 psig challenge, both sets of test units removed all three viruses
to less than detectible levels (< 1 PFU/mL). The maximum mean effluent count for the pH 9, 80
psig challenges was 11 PFU/mL (3.0 logic fr reduction for unconditioned unit 3). As with the
bacteria, the prevalence of undetectable virus effluent counts does not allow an evaluation of the
effect of conditioning, inlet pressure, or pH on RO membrane performance.
17
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Table 4-4. Virus Log Reduction Data for Unconditioned Units
Challenge Conditions
Target Actual Pressure Challenge
pH pH (psig) Organisms
6.0 ±0.5 6.86
6.0 ±0.5 6.88
7.5 ±0.5 7.69
7.5 ±0.5 7.91
9.0 ±0.5 8.71
9.0 ±0.5 8.67
40 fr
MS2
Phi X 174
80 fr
MS2
Phi X 174
40 fr
MS2
Phi X 174
80 fr
MS2
Phi X 174
40 fr
MS2
Phi X 174
80 fr
MS2
Phi X 174
Log10
Influent
Challenge
5.0
4.8
4.5
5.4
5.2
4.0
4.3
5.0
5.3
4.0
4.9
4.4
5.3
5.0
4.4
4.1
3.9
3.7
Geometric Mean Logio Reduction
Unit 1 Unit 2 Unit 3 Unit 4 Unit 5
5.0
4.8
4.5
5.4
5.2
4.0
4.3
5.0
5.3
4.0
4.9
4.4
5.3
5.0
4.4
3.8
3.9
3.7
5.0
4.8
4.5
5.4
5.2
4.0
4.3
5.0
5.3
4.0
4.9
4.4
5.3
5.0
4.4
3.6
3.6
3.7
5.0
4.8
4.5
5.4
5.2
4.0
4.3
5.0
5.3
4.0
4.9
4.4
5.3
5.0
4.4
3.0
2.9
3.7
5.0
4.8
4.5
5.4
5.2
4.0
4.3
5.0
5.3
4.0
4.9
4.4
5.3
5.0
4.4
4.1
3.9
3.7
5.0
4.8
4.5
5.4
5.2
4.0
4.3
5.0
5.3
4.0
4.9
4.4
5.3
5.0
4.4
4.1
3.9
3.7
Table 4-5. Virus Log Reduction Data for Conditioned Units
Challenge Conditions
Target Actual Pressure
pH pH (psig)
6.0 ±0.5 6.48 40
6.0 ±0.5 6.69 80
7.5 ±0.5 7.45 40
7.5 ±0.5 7.56 80
9.0 ±0.5 8.73 40
9.0 ±0.5 8.73 80
Challenge
Organisms
fr
MS2
Phi X 174
fr
MS2
Phi X 174
fr
MS2
Phi X 174
fr
MS2
Phi X 174
fr
MS2
Phi X 174
fr
MS2
PhiX 174
Log10
Influent
Challenge
4.8
4.5
3.8
4.5
4.4
4.2
5.3
4.9
4.3
4.9
4.7
3.9
5.6
5.4
3.8
5.1
4.8
4.5
Geometric Mean Logio Reduction
Unit 1 Unit 2 Unit 3 Unit 4 Unit 5
4.8
4.5
3.8
4.5
4.4
4.2
5.3
4.9
4.3
4.9
4.7
3.9
5.6
5.4
3.8
5.1
4.5
4.5
4.8
4.5
3.8
4.5
4.4
4.2
5.3
4.9
4.3
4.9
4.7
3.9
5.6
5.4
3.8
4.6
4.3
4.5
4.8
4.5
3.8
4.5
4.4
4.2
5.3
4.9
4.3
4.9
4.7
3.9
5.6
5.4
3.8
5.1
4.8
4.5
4.8
4.5
3.8
4.5
4.4
4.2
5.3
4.9
4.3
4.9
4.7
3.9
5.6
5.4
3.8
5.1
4.8
4.5
4.8
4.5
3.8
4.5
4.4
4.2
5.3
4.9
4.3
4.9
4.7
3.9
5.6
5.4
3.8
5.1
4.5
4.5
18
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Chapter 5
QA/QC
5.1 Data Review
NSF QA/QC staff reviewed the raw data records for compliance with QA/QC requirements and
checked 100% of the data against the reported results in the official laboratory reports.
5.2 Test Procedure QA/QC
The test procedure followed an NSF SOP created specifically for this ETV.
5.3 Water Chemistry Analytical Methods QA/QC
pH - Three point calibration at pH 4, 7, and 10 was conducted daily using traceable
buffers. The calibration was checked with a pH 8 buffer. The precision of the instrument
was checked by collecting a sample of municipal drinking water and splitting it into two
samples for pH measurement. The relative percent deviation (RPD) was calculated using
the equation in section 5.7.3. The acceptable RPD limit was 10%. The daily pH 8 buffer
readings and results of the duplicate analyses are given in Table B-l of Appendix B.
Temperature - The digital thermometer is calibrated every six months using a Hart
Scientific Model 9105 Dry Well Calibrator.
Total Chlorine - The spectrophotometer was calibrated daily according to the
manufacturer's instructions. The precision of the instrument was checked daily by
analyzing a sample of municipal drinking water in duplicate. The samples were diluted
by approximately 50% with deionized water, and then split into subsamples for analysis.
The RPD for the two samples was then calculated, with an acceptable RPD limit of 10%.
The results of the duplicate analyses are given in Table B-3 of Appendix B.
TDS - Two potassium chloride standards were used for instrument calibration. A third
QC standard was then used to check the calibration. Ten percent of samples were
analyzed in duplicate, and RPDs were calculated. The acceptable RPD limit was 10%.
The calibration check standard measurements and results of the duplicate analyses are
given in Table B-2 of Appendix B.
5.4 Microbiology Laboratory QA/QC
5.4.1 Growth Media
All media were checked for sterility and positive growth response when prepared and when used
for microorganism enumeration. The media was discarded if growth occurred on the sterility
check media, or if there was an absence of growth in the positive response check. All three E.
coli hosts for the viruses were plated on TSA and incubated with the virus enumeration plates
during sample enumeration as a second positive growth control. B. diminutaand H. pseudoflava
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from the stock cultures were plated on R2A agar and incubated with the bacteria enumeration
plates as positive controls.
5.4.2 Bacteria Cell Size
The theoretical minimum size for B. diminuta and H. pseudoflava cells is 0.2 to 0.3 jam in
diameter, however, the NSF Microbiology Laboratory was not able to achieve that size. The
stock culture was examined microscopically using a stage micrometer, and the observed
diameters were approximately 0.5 urn. To achieve the smallest cell size, the bacteria need to be
grown in a medium such as Saline Lactose Broth that keeps the cells small due to osmotic
pressure constraints. However, this medium is low in nutrients, so the Microbiology Laboratory
had difficulty cultivating the bacteria in high liters. The bacteria were instead cultivated in TSB.
TSB is more nutrient rich, and as a result yielded larger cells.
The larger cell size may have enhanced the bacteria reduction performance of the test units, so
the bacteria reduction data cannot be used to predict expected performance against bacterial
agents smaller than 0.5 um. However, the viruses used in this study are much smaller than any
bacteria, so the virus results could be considered indicative of the system's minimum bacteria
reduction performance.
5.4.3 Sample Processing and Enumeration
All samples were enumerated in triplicate. For each sample batch processed, an unused
membrane filter and a blank with 100 mL of PBDW filtered through the membrane were also
placed onto the appropriate media and incubated with the samples as negative controls. No
growth was observed on any blanks.
5.5 Sample Handling
All samples analyzed by the NSF Microbiology and Wet Chemistry Laboratories were labeled
with unique ID numbers. These ID numbers appear on the NSF laboratory reports for the tests.
All water chemistry samples were analyzed within allowable hold times. All samples for
bacteria and virus analysis were processed within one hour of collection.
5.6 Documentation
All laboratory activities were documented using laboratory bench sheets and NSF laboratory
reports. This documentation can be found in the appendices.
5.7 Data Quality Indicators
The quality of data generated for this ETV can be established through five indicators of data
quality: representativeness, accuracy, precision, statistical uncertainty, and completeness.
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5.7.1 Representativeness
Representativeness refers to the degree to which the data accurately and precisely represent the
expected performance of the RO system under normal use conditions. The test protocol was
designed to be a conservative evaluation of product performance. The test water was of very low
turbidity to minimize the potential of microbial adhesion to suspended particles, which could
enhance apparent log reduction. The surrogates were chosen because of their small size. The
virus surrogate challenges were carried out at pH 6, 7.5, and 9 to assess whether pH affects the
performance of the RO membrane.
5.7.2 Accuracy
Accuracy of the pH meter was evaluated with a pH 8.0 check standard after the daily
calibrations. The calibration check measurements were all in the range 7.91 to 8.10.
Accuracy of the conductivity meter used for TDS analysis was measured through the use of QC
samples with every batch of samples analyzed. Two batches of samples were analyzed, one for
each set of test units. The percent recovery of the QC samples analyzed with these batches was
102% and 103%.
During most of the testing period, the chlorine meter's accuracy was checked by measuring the
chlorine level of deionized water samples. The calibration was acceptable if the measured
chlorine level was 0.05 mg/L or less. Deionized water was chosen to be the calibration check
because the test plan called for the use of deionized water for the test water, and that this water
have a chlorine level less than or equal to 0.05 mg/L. Thus, the calibration check measured the
accuracy of the meter for the range in which the test water samples fell. Toward the end of the
testing period, the testing laboratory began also using three different check standards in addition
to deionized water. The readings for the check standards had to be within 10% of the true value
for acceptable calibration.
Accuracy check results for these parameters are given in Appendix B.
5.7.3 Precision
Precision refers to the degree of mutual agreement among individual measurements and provides
an estimate of random error. One sample per batch was analyzed in duplicate for the TDS
measurements. Duplicate municipal drinking water samples were analyzed for pH and total
chlorine as part of the daily calibration process. Precision of the duplicate analyses was
measured by use of the following equation to calculate relative percent deviations (RPD):
: 200
where:
Sl = sample analysis result; and
£2 = sample duplicate analysis result.
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The RPD calculations for individual duplicate pairs are given in the tables in Appendix B. The
duplicate measurements for the two TDS sample batches gave RPD values of 0.5% and 1.5%.
The RPD values for the pH measurements ranged from 0% to 0.88%. The RPD values for the
total chlorine measurements ranged from 0% to 5.96%.
5.7.4 Statistical Uncertainty
Statistical Uncertainty is expressed using 95% confidence intervals. No confidence interval
calculations were made for the performance data because most of the effluent samples contained
undetectable concentrations of the challenge organisms, and the sample sizes (triplicate counts)
were too small to give very meaningful results.
5.7.5 Completeness
Completeness is the proportion of valid, acceptable data generated using each method as
compared to the requirements of the test/QA plan. The completeness objective for data
generated during verification testing is based on the number of samples collected and analyzed
for each parameter and/or method.
Table 5-1. Completeness Requirements
Number of Samples per Percent
Parameter and/or Method Completeness
0- 10 80%
11 - 50 90%
> 50 95%
Completeness is defined as follows for all measurements:
%C = (V/T)X100
where:
%C = percent completeness;
V = number of measurements judged valid; and
T = total number of measurements.
5.7.5.1 Completeness Measurements
Ten units were tested, as called for in the test/QA plan, giving a completeness
measurement of 100% for this category.
All conditioning water and challenge water samples for pH, temperature, total chlorine,
and TDS (by conductivity) were collected as scheduled and analyzed with acceptable
results.
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All scheduled bacteria and virus samples were collected and analyzed with acceptable
results. As described in Section 3.2.3.2, the influent samples for the H. pseudoflava
challenges for both groups of test units were considerably less than the target levels.
However, these challenges were conducted again at the end of the testing period, with
acceptable challenge levels.
5.8 Measurements Outside of the Test/QA Plan Specifications
5.8.1 Total Chlorine
The test/QA plan called for the test water to have a total chlorine level at or below 0.05 mg/L.
On day 24 of the conditioning period for the conditioned units, the influent chlorine level was
measured at 0.06 mg/L. This is not a significant deviation from the test plan.
5.8.2 pH
The test water chemistry provided little buffering capacity, which made it difficult to keep the
pH of the test water within the allowable range (+ 0.5) for the pH 6 and pH 9 challenges. The
influent pH readings for the unconditioned units' pH 6, 40 psig, and pH 6, 80 psig challenges,
and the conditioned units pH 6, 80 psig challenge were all above the allowable upper limit of pH
6.5. See Tables 4-4 and 4.5 for the pH measurements. These deviations are significant,
however, since there is not any effluent count data with which to compare test unit performance
at the three different pH values, these deviations do not affect any data analysis.
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Chapter 6
References
American Society of Testing Materials (2001). D 3862-80, Standard Test Method for Retention
Characteristics of 0.2-|j,m Membrane Filters Used in Routine Filtration Procedures for the
Evaluation of Microbiological Water Quality.
NSF International (2002). NSF/ANSI55-2002, Ultraviolet microbiological water treatment
systems. Ann Arbor, NSF International.
NSF International (2002). NSF/ANSI 58 - 2002, Reverse osmosis drinking water treatment
systems. Ann Arbor, NSF International.
APHA, AWWA and WPCF (1998). Standard Methods for Examination of Water and
Wastewater. 20th ed. Washington, D.C. APHA.
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