September 2009
NSF 09/32/EPADWCTR
EPA/600/R-09/110
Environmental Technology
Verification Report
Removal of Microbial Contaminants in
Drinking Water
Siemens Corporation
Memcor® S10V Ultrafiltration Module
Prepared by
NSF International
Under a Cooperative Agreement with
U.S. Environmental Protection Agency
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THE ENVIRONMENTAL TECHNOLOGY VERIFICATION
PROGRAM
oEPA
ET
V^lVl
V
U.S. Environmental Protection Agency
NSF International
ETV Joint Verification Statement
TECHNOLOGY TYPE: ULTRAFILTRATION
APPLICATION: REMOVAL OF MICROBIAL CONTAMINANTS
PRODUCT NAME: MEMCOR® S10V ULTRAFILTRATION MODULE
VENDOR: SIEMENS WATER TECHNOLOGIES CORPORATION
ADDRESS: 181 THORN HILL ROAD
WARRENDALE, PA 15086
PHONE: 724-772-0044
EMAIL: INFORMATION.WATER@SIEMENS.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 Siemens Memcor® L20V ultrafiltration module
for removal of microbial contaminants under controlled laboratory challenge conditions. The challenge
tests were conducted at NSF's testing laboratory in Ann Arbor, MI. Testing of the Siemens Memcor®
L20V ultrafiltration membrane module was conducted to verify microbial reduction performance under
the membrane challenge requirements of the USEPA Long Term 2 Enhanced Surface Water Treatment
Rule (LT2ESWTR).
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 09/32/EPADWCTR The accompanying notice is an integral part of this verification statement. September 2009
VS-i
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ABSTRACT
The Siemens Memcor S10V UF module was tested for removal of endospores of the bacteria Bacillus
atrophaeus and the MS2 coliphage virus according to the requirements of the EPA Long-Term 2
Enhanced Surface Water Treatment Rule (LT2ESWTR). B. atrophaeus served as a surrogate for
Cryptosporidium oocysts, as well as other bacteria. Five modules from five different production lots were
challenged with both organisms. Separate challenges were conducted for each organism. The modules
were operated at a target flux of 80 gallons per square foot per day (gfd), which for the S10V equates to
approximately 16.7 gallons per minute (gpm).
The LT2ESWTR specifies that log removal values (LRV) be calculated for each module for each
organism, and then one LRV for each organism (LRVc-TEsi) be assigned from the set of LRV. However,
the rule does not specify how the LRVC.TEST should be determined, instead, three different methods are
suggested. All three methods were used to assign LRV for this verification. See the Verification of
Performance section below for descriptions of each method. The LRVC.TEST for each method are
presented in Table VS-i.
Table VS-i. LRVC-TEsx for Each Organism
Challenge
Organism
B. atrophaeus
MS2
Method 1
7.10
2.98
Method 2
7.13
3.00
Method 3
6.62
2.57
PRODUCT DESCRIPTION
The Memcor S10V UF membrane module is a member of the Memcor CS line of products. The Memcor
CS modules are submerged membranes that operate by pulling water through the membrane from the
outside to the inside of the hollow fiber using vacuum pressure. The module measures 5.2 inches in
diameter by 46.7 inches in length. The membrane fibers are made of polyvinylidene fluoride (PVDF).
The modules operate in a dead-end mode, with no reject stream. The nominal pore size is 0.04 (im.
Siemens supplied five modules from five different production runs for testing. The modules were tested
in a pilot unit supplied by Siemens.
VERIFICATION TEST DESCRIPTION
Challenge Organisms
The S10V modules were tested for removal of microorganisms using endospores of the bacteria Bacillus
atrophaeus (ATCC 9372, deposited as Bacillus subtilis var. niger), and MS-2 coliphage virus (ATCC
15597-B1). B. atrophaeus served as a surrogate for Cryptosporidium oocysts, as well as other bacteria.
B. atrophaeus endospores are ellipsoidal (football shaped), with an average diameter of 0.8 (im, and an
average length of 1.8 (im. A full discussion of the rationale for using Bacillus endospores as a surrogate
for Cryptosporidium can be found in the verification report. Virus removal testing was conducted using
MS-2 for possible virus removal credits. MS-2 is considered a suitable surrogate for pathogenic viruses
because of its small size, at 24 nm in diameter. Separate challenge tests were conducted for each
challenge organism, so each module was tested twice over the course of the testing activities.
Test Site and Challenge Water
The microbial challenge tests were conducted at NSF's testing laboratory in Ann Arbor, MI. Local tap
water was treated sequentially by carbon filtration, reverse osmosis, ultraviolet disinfection, and
deionization to make the base water for the tests. A water supply tank was filled with the base water, and
NSF 09/32/EPADWCTR
The accompanying notice is an integral part of this verification statement. September 2009
VS-ii
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sodium bicarbonate was added in sufficient quantity to provide alkalinity at a target of 100 ± 10 mg/L as
calcium carbonate. The pH was then lowered with hydrochloric acid to a target range of 7.5 ± 0.5.
Methods and Procedures
The tests followed the procedures described in the Test/QA Plan for the Microbial Seeding Challenge
Study of the Siemens Memcor L10V, L20V, and S10V Ultrafiltration Modules. The challenge protocol
was adapted from the ETV Protocol for Equipment Verification Testing for Physical Removal of
Microbiological and Paniculate Contaminants, and the USEPA Membrane Filtration Guidance Manual
(MFGM).
The pilot unit holds four modules, but only one module was tested at a time. For the other membrane
slots, Siemens provided cartridge ends with fibers that had been epoxied shut. The target flux for the tests
was 80 gallons per square foot per day (gfd), which equals a flow rate of 16.7 gallons per minute (gpm)
for the S10V module.
Before and after each challenge test, each module was subjected to a two minute pressure decay test using
the program in the pilot unit's programmable logic controller (PLC). Siemens defined a passing pressure
decay test as less than or equal to 1.5 psi per minute. The PLC gives a warning message if this decay rate
is exceeded.
Prior to the start of each challenge test, the module and pilot unit were flushed for approximately two
minutes, and then at the end of the flush a negative control sample was collected from the filtrate sample
tap. The duration of each microbial challenge test was 30 minutes. Feed and filtrate samples were
collected for challenge organism enumeration after three minutes of operation, after 15 minutes of
operation, and after 30 minutes of operation. The challenge organisms were intermittently injected into
the feed stream for five-minute periods using a peristaltic pump at each sampling point. The injection
point was downstream of the pilot unit's feed tank, as shown in Figure 2-2. During each injection period,
the challenge organism was fed to the feed stream for at least 3 minutes prior to collection of the feed and
filtrate samples during the fourth and/or fifth minutes. At the end of each challenge test, a second
pressure decay test was conducted to confirm membrane integrity.
The MFGM suggests that feed and filtrate samples not be collected until at least three hold-up volumes of
water containing the challenge organism have passed through the membrane, to establish equilibrium
(equilibrium volume). The hold-up volume is defined as the "unfiltered test solution volume that would
remain in the system on the feed side of the membrane at the end of the test." Siemens has calculated the
hold-up volume of the Memcor XP pilot unit as 40 gallons, not including the unit's feed tank. The flow
rates measured during ETV testing ranged from 16.70 to 16.96 gpm, so only approximately 50 gallons of
the spiked test solution passed through the membrane modules before sample collection began. This
volume was less than the equilibrium volume of 120 gallons, but the MS-2 filtrate counts suggest that the
membranes were being subjected to the full challenge concentration when the filtrate samples were
collected. The feed samples were collected upstream from the membrane holding chamber, so they are
not indicative of the challenge concentration in the membrane chamber after 3 minutes of injection.
However, most of the MS-2 filtrate counts for the S10V challenges were above IxlO3 PFU/mL. These
filtrate counts were similar to those measured from the ETV challenge tests of the Siemens L10V and
L20V membranes, which use the same UF fibers. So, the fact that the S10V filtrate counts were similar
to those from the L10V and L20V tests indirectly indicates that the S10V cartridges were exposed to
adequate MS-2 challenge concentrations after only 3 minutes of injection.
NSF 09/32/EPADWCTR The accompanying notice is an integral part of this verification statement. September 2009
VS-iii
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VERIFICATION OF PERFORMANCE
The LT2ESWTR and MFGM specify that an LRV for the test (LRVc-TEsi) be calculated for each module
tested, and that the LRV for each module are then combined to yield a single LRVc-TEsi for the product.
If fewer than 20 modules are tested, as was the case for this verification, the LRVC.TEST is simply the
lowest LRV for the individual modules. However, the rule does not specify a method to calculate LRVC.
TEST for each module. Suggested options in the MFGM include the following: calculating a LRV for each
feed/filtrate sample pair, then calculating the average of the LRV (Method 1); averaging all of the feed
and filtrate counts, and then calculating a single LRV for the module (Method 2); or calculating a LRV
for each feed/filtrate sample pair, and then selecting the LRV for the module as the lowest (most
conservative of the three options, Method 3).
All three approaches for calculating the LRV are reported here. Note the LT2ESWTR and MFGM do not
specify whether the averages should be calculated as the arithmetic mean or geometric mean. For this
verification, geometric means were calculated.
All pressure decay rates were below 0.7 psig/min, indicating that there were no membrane integrity issues
during the tests.
B. atrophaeus Reduction
The LT2ESWTR indicates a maximum challenge concentration to achieve a reduction of 6.5 logio
(3.16xl06 CPU/100 mL). The B. atrophaeus feed concentrations for these tests ranged from 3.6xl07 to
6.1xl07 CFU/100 mL, taking into account the expected percent recovery of the challenge organism,
which is typically less than 100%. The B. atrophaeus LRV from the three different calculation methods
are presented in Table VS-ii. The LRVC.TEST for each method is in bold font. The LT2ESWTR specifies
that the maximum possible LRVc-iEsi awarded to a membrane product is 6.5 logio, but the LRV above
6.5 are still presented here.
No B. atrophaeus endospores were found in the Module 1 filtrate samples, but they were found at low
levels in the filtrate samples for the rest of the modules. The maximum observed filtrate count was 10
CFU/100 mL. The flow rates measured during the B. atrophaeus challenges translated into fluxes
ranging from 80.3 to 81.2 gfd.
Table VS-ii. B. atrophaeus LRV Calculations
Module #
Module 1
Module 2
Module 3
Module 4
Module 5
Method 1
7.71
7.39
7.10(1)
7.53
7.24
Method 2
7.71
7.36
7.13(1)
7.63
7.28
Method 3
7.66
7.09
6.62(1)
7.26
6.81
(1) LRVc-TEsi under these two methods should be capped at 6.5.
MS-2 Reduction
The MS-2 feed concentrations ranged from 1.42xl06 PFU/mL to 9.0xl06 PFU/mL. The LRV for MS-2
reduction are shown in Table VS-iii. The LRVc-TEST for each method is in bold font. The maximum
individual filtrate count was 9.3xl03 PFU/mL for Module 1 30-minute sample. The flow rates measured
during the MS-2 challenges translated into fluxes ranging from 80.2 to 81.4 gfd.
NSF 09/32/EPADWCTR
The accompanying notice is an integral part of this verification statement. September 2009
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Table VS-iii. MS-2 LRV Calculations
Module #
Module 1
Module 2
Module 3
Module 4
Module 5
Method 1
2.98
3.19
3.24
3.16
3.64
Method 2
3.00
3.20
3.23
3.17
3.64
Method 3
2.57
3.09
3.12
2.94
3.61
QUALITY ASSURANCE/QUALITY CONTROL (QA/QC)
NSF provided technical and quality assurance oversight of the verification testing as described in the
verification report, including a review of 100% of the data. NSF QA 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.
Original signed by Sally Gutierrez 09/30/09
Sally Gutierrez Date
Director
National Risk Management Research
Laboratory
Office of Research and Development
United States Environmental Protection
Agency
Original signed by Robert Ferguson 11/05/09
Robert Ferguson Date
Vice President
Water Systems
NSF International
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.
Availability of Supporting Documents
Copies of the test protocol, the verification statement, and the verification report (NSF
report # NSF 09/32/EPADWCTR) are available from the following sources:
1. ETV Drinking Water Systems Center Manager (order hard copy)
NSF International
P.O. Box 130140
Ann Arbor, Michigan 48113-0140
2. Electronic PDF copy
NSF web site: http://www.nsf.org/info/etv
EPA web site: http://www.epa.gov/etv
NSF 09/32/EPADWCTR
The accompanying notice is an integral part of this verification statement. September 2009
VS-v
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September 2009
Environmental Technology Verification Report
Removal of Microbial Contaminants in Drinking Water
Siemens Corporation
Memcor® S10V Ultrafiltration Module
Prepared by:
Mike Blumenstein, Senior Project Manager
Bruce Bartley, Technical Manager
NSF International
Ann Arbor, Michigan 48105
and
Jeffrey Q. Adams, Project Officer
National Risk Management Research Laboratory
U.S. Environmental Protection Agency
Cincinnati, Ohio 45268
Under a cooperative agreement with the U.S. Environmental Protection Agency
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Notice
The U.S. Environmental Protection Agency, through its Office of Research and Development,
funded and managed, or partially funded and collaborated in, the research described herein. It
has been subjected to the Agency's peer and administrative review and has been approved for
publication. Any opinions expressed in this report are those of the author(s) and do not
necessarily reflect the views of the Agency, therefore, no official endorsement should be inferred.
Any mention of trade names or commercial products does not constitute endorsement or
recommendation for use.
11
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Foreword
The EPA is charged by Congress with protecting the nation's air, water, and land 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, the EPA's Office of Research and
Development provides data and science support that can be used to solve environmental
problems and to build the scientific knowledge base needed to manage our ecological resources
wisely, to understand how pollutants affect our health, and to prevent or reduce environmental
risks.
The Environmental Technology Verification (ETV) Program has been established by the EPA to
verify the performance characteristics of innovative environmental technology across all media
and to report this objective information to permitters, buyers, and users of the technology, thus
substantially accelerating the entrance of new environmental technologies into the marketplace.
Verification organizations oversee and report verification activities based on testing and quality
assurance protocols developed with input from major stakeholders and customer groups
associated with the technology area. ETV consists of six environmental technology centers.
Information about each of these centers can be found on the internet at http://www.epa.gov/etv.
Under a cooperative agreement, NSF International has received EPA funding to plan, coordinate,
and conduct technology verification studies for the ETV "Drinking Water Systems Center" and
report the results to the community at large. The DWS Center has targeted drinking water
concerns such as arsenic reduction, microbiological contaminants, particulate removal,
disinfection by-products, radionuclides, and numerous chemical contaminants. Information
concerning specific environmental technology areas can be found on the internet at
http://www.epa.gov/nrmrl/std/etv/verifications.html.
in
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Acknowledgments
The authors wish to acknowledge the support of all those who helped plan and conduct the
verification test, analyze the data, and prepare this report. We sincerely appreciate the
involvement and support of all staff from the NSF testing laboratory who were involved with
testing activities for this verification. In particular, we would like to thank Mr. Sal Aridi, P.E.,
laboratory manager, and Mr. Kevin Schaefer, the testing engineer for this project. The NSF
Microbiology Laboratory analyzed all of the feed and filtrate samples for the tests. From this
laboratory, the authors would like to thank Robert Donofrio, PhD, Director of the NSF
Microbiology Laboratory, Robin Bechanko, Senior Microbiologist, and Kathy O'Malley,
Microbiologist. From the NSF QA Department, the authors wish to thank Joe Terrell,
Supervisor of QA and Safety, for auditing the tests and also reviewing all of the test data.
Finally, we would like to thank Patrick Cook of the Michigan Department of Environmental
Quality, and Jonathan Pressman of the U.S. EPA, for their reviews of this verification report.
IV
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Table of Contents
Verification Statement VS-i
Title Page i
Notice ii
Foreword iii
Acknowledgements iv
Table of Contents v
List of Tables vi
List of Figures vi
Abbreviations and Acronyms vii
Chapter 1 Introduction 1
1.1 ETV Program Purpose and Operation 1
1.2 Purpose of Verification 1
1.3 Testing Participants and Responsibilities 1
1.3.1 NSF International 2
1.3.2 U.S. Environmental Protection Agency 2
1.3.3 Siemens Corporation 2
Chapter 2 Product Description 3
2.1 UF Membrane General Description 3
2.2 Memcor S10V Membrane Module Description 3
2.3 Pilot Unit Used for Testing 4
Chapter 3 Methods and Procedures 7
3.1 Introduction 7
3.2 Challenge Organisms 7
3.3 UF Module Integrity Tests 8
3.4 Test Water Composition 8
3.5 Challenge Test Procedure 8
3.6 Analytical Methods 9
Chapter 4 Results and Discussion 11
4.1 Pressure Decay Test Results 11
4.2 B. atrophaeus Challenge Tests 12
4.2.1 Choosing LRVc-xEsx from the Averages of the Individual LRV Calculations 12
4.2.2 LRVc-TEsx Calculated from the Mean Feed and Filtrate Counts 12
4.2.3 Choosing LRVc-xEsx from the Individual Sample Point LRV Calculations 13
4.3 MS-2 Challenge Tests 14
4.3.1 Choosing LRVc-xEsx from the Averages of the Individual LRV Calculations 14
4.3.2 LRVc-xEsx Calculated from the Mean Feed and Filtrate Counts 14
4.3.3 Choosing LRVc-xEsx from the Individual Sample Point LRV Calculations 14
4.4 Operational Data and Water Quality Data for All Challenges 16
Chapter 5 Quality Assurance/Quality Control 17
5.1 Introduction 17
5.2 Test Procedure QA/QC 17
5.3 Sample Handling 17
5.4 Chemistry Laboratory QA/QC 17
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5.5 Microbiology Laboratory QA/QC 17
5.5.1 Growth Media Positive Controls 17
5.5.2 Negative Controls 18
5.6 Documentation 18
5.7 Data Review 18
5.8 Data Quality Indicators 18
5.8.1 Representativeness 18
5.8.2 Accuracy 18
5.8.3 Precision 19
5.8.4 Completeness 19
Chapter 6 References 21
Appendices
Appendix A Test/Quality Assurance Project Plan
Appendix B Bacillus Endospores as a Surrogate for Cryptosporidium parvum
Appendix C Challenge Organism Triplicate Counts
List of Tables
Table 2-1. S10V Specifications 3
Table 2-2. Serial Numbers of Tested Modules 4
Table 3-1. Analytical Methods for Laboratory Analyses 10
Table 4-1. Pressure Decay Data 11
Table 4-2. B. atrophaeus Challenge Results 13
Table 4-3. B. atrophaeus LRVc-xEsx Calculated from the Mean Feed and Filtrate Counts 13
Table 4-4. B. atrophaeus LRVc-xEsx from Individual LRV 14
Table 4-5. MS-2 Challenge Results 15
Table 4-6. MS-2 LRVC-xEsx Calculated from the Mean Feed and Filtrate Counts 15
Table 4-7. MS-2 LRVC-xEsx from Individual LRV 15
Table 4-8. Operation Data 16
Table 4-9. Water Chemistry Data 16
Table 5-1. Completeness Requirements 19
List of Figures
Figure 2-1. Siemens Memcor CMF-S pilot unit 5
Figure 2-2. Challenge organism injection point and feed sample tap on pilot unit
VI
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Abbreviations and Acronyms
ATCC American Type Culture Collection
°C degrees Celsius
CPU colony forming units
cm centimeter
DWS Drinking Water Systems
EPM Electrophoretic Mobility
ETV Environmental Technology Verification
°F degrees Fahrenheit
ft foot(feet)
gfd gallons per square foot per day
gpm gallons per minute
in inch(es)
kPa kilopascals
L liter
LRV log removal value
LT2ESWTR Long Term 2 Enhanced Surface Water Treatment Rule
m meter
MFGM Membrane Filtration Guidance Manual
mg milligram
min minute
mL milliliter
mm millimeter
mM millimolar
MWCO molecular weight cutoff
NM not measured
NSF NSF International (formerly known as National Sanitation Foundation)
NTU Nephelometric Turbidity Unit
ORD Office of Research and Development
PFU plaque forming unit
PLC programmable logic controller
psig pounds per square inch, gauge
PVDF polyvinylidene fluoride
QA quality assurance
QC quality control
RPD relative percent difference
SM Standard Methods for the Examination of Water and Wastewater
TDS total dissolved solids
TOC total organic carbon
UF ultrafiltration
ug microgram
jam micrometer
uS microsiemens
USEPA U. S. Environmental Protection Agency
vn
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Chapter 1
Introduction
1.1 ETV Program Purpose and Operation
The U.S. Environmental Protection Agency (USEPA) has created the Environmental Technology
Verification (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;
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 USEPA 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 USEPA. 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 Purpose of Verification
Testing of the Siemens Memcor® S10V ultrafiltration (UF) membrane module was conducted to
verify microbial reduction performance under the membrane challenge requirements of the
USEPA Long Term 2 Enhanced Surface Water Treatment Rule (LT2ESWTR). Please note that
this verification only addresses the challenge testing requirement of the LT2ESWTR, not direct
integrity testing or continuous indirect monitoring.
Please also note that this verification does not address long-term performance, or performance
over the life of the membrane. This verification test did not evaluate cleaning of the membranes,
nor any other maintenance and operation.
1.3 Testing Participants and Responsibilities
The following is a brief description of each of the ETV participants and their roles and
responsibilities.
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1.3.1 NSF International
NSF is an independent, not-for-profit organization dedicated to public health and safety, and to
protection of the environment. Founded in 1944 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 USEPA partnered with NSF to verify the performance of drinking
water treatment systems through the USEPA's ETV Program.
NSF performed all verification testing activities at its Ann Arbor, MI 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: Mr. Bruce Bartley, Project Manager
Email: bartley@nsf.org
1.3.2 U.S. Environmental Protection Agency
USEPA, through its Office of Research and Development (ORD), has financially supported and
collaborated with NSF under Cooperative Agreement No. CR-833980-01. This verification
effort was supported by the DWS Center operating under the ETV Program. This document has
been peer-reviewed, reviewed by USEPA, and recommended for public release.
1.3.3 Siemens Corporation
Siemens Corporation supplied the tested membrane modules, and also a pilot testing unit in
which the membranes were tested. Siemens was also responsible for providing logistical and
technical support, as needed.
Contact Information: Siemens Water Technologies Corp.
725 Wooten Road
Colorado Springs, CO, 80915
Phone: +1 (719) 622-5326
Fax: +1 (719) 622-5399
Contact: Mr. Aaron Balczewski, Director of Process Technology,
Memcor Products
Email: Aaron.Balczewski(3)siemens.com
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Chapter 2
Product Description
2.1 UF Membrane General Description
UF membranes remove contaminants from water through sieving based on the size of the
membrane pores relative to the physical size of the contaminant. A common arrangement for the
membranes is in hollow fibers, with the fibers "potted" in a resin. The flow of water through the
fibers can be either "inside-out" or "outside-in". UF membranes can be classified by pore size or
the molecular weight cutoff (MWCO) point. Pore sizes generally range from 0.01 to 0.05
microns (nm). Typical MWCO points are 10,000 to 500,000 Daltons, with 100,000 being a
common MWCO rating for drinking water treatment. With these specifications, UF membranes
can remove viruses, bacteria, and protozoan cysts, as well as large molecules such as proteins,
and suspended solids.
2.2 Memcor S10V Membrane Module Description
The Memcor S10V UF membrane module is a member of the Memcor CS line of products. The
Memcor CS modules are submerged membranes that operate by pulling water through the
membrane from the outside to the inside of the hollow fiber using vacuum pressure. The S10V
module measures 5.2 inches in diameter by 46.7 inches in length. The membrane fibers are
made of polyvinylidene fluoride (PVDF). The module specifications are listed below in Table 2-
1. The identification numbers and serial numbers for the tested modules are listed in Table 2-2.
Five modules from five different production lots were submitted by Siemens for testing. The
assigned module numbers in Table 2-2 correspond to the module numbers in the Results and
Discussion chapter.
Table 2-1. S10V Specifications
Parameter
Dimensions:
Cartridge outside diameter
Cartridge length
Nominal membrane pore size
Maximum membrane pore size
Average active membrane area (outer)
Operating Limits:
Operating temperature range
Maximum temperature
Max. transmembrane pressure
Operating pH range
Specification
5.2 inches (in) (131 millimeters (mm))
46.7 in (1186 mm)
0.04 urn
0.1 urn
300 square feet (ft2) (27.9 square meters (m2))
>32 - 104 Fahrenheit (°F) (>0 - 40 Celcius (°C))
113°F(45°C)
17.4 pounds per square inch, gauge (psig) (120 kilopascals (kPa))
2-10
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Table 2-2. Serial Numbers of Tested Modules
Module
1
2
3
4
5
Batch Number
31685
29480
33092
33075
31116
Identification Number
WJ75E34H
WK68C634
WM7AC21B
WM7AA64B
WJ73122L
(1) NR: not recorded
2.3 Pilot Unit Used for Testing
Siemens supplied a pilot unit for testing along with the membrane cartridges. A photo of the
pilot unit in the testing laboratory is shown as Figure 2-1. The pilot unit holds four membrane
cartridges, but only one cartridge was tested at a time. For the other membrane slots, Siemens
supplied cartridge ends with fibers that had been epoxied shut. The pilot unit programmable
logic controller (PLC) includes an automatic pressure decay test program. This program was
used to evaluate the integrity of the membranes before and after each microbial challenge test.
The pilot unit automatic backflush feature was disabled for the tests.
The target flow rate was entered into the PLC, and the PLC then controlled the flow through the
pilot unit using internal pumps and pneumatic valves. However, the filtrate flow data presented
in the results and discussion chapter was collected from an NSF installed flow meter (Great
Plains Industries model A109GNA100NA10) on the filtrate line. The accuracy of the flow meter
was verified prior to testing using the "bucket and stopwatch" method. The pressure drop across
the membrane was measured using a differential pressure transducer supplied by Siemens on the
pilot unit. The accuracy of this sensor was verified prior to testing by an NSF calibration officer.
The feed water minus the challenge organism was pumped from NSF's feed tank into the pilot
unit. The pilot unit uses a vacuum pump to draw water across the membranes. The rate of the
NSF feed pump was set to be equal to that of the pilot unit vacuum pump, such that a constant
water level was maintained in the membrane cartridge chamber. The challenge organism was
injected into the pilot unit plumbing upstream of the membrane chamber. To allow for adequate
mixing of the organism, the V SEP A Membrane Filtration Guidance Manual (EPA 815-R-06-
009) calls for the challenge organism injection point to be more than ten pipe diameters upstream
from the feed water sample tap. This was accomplished, and there were also two 90-degree pipe
bends and a turbine flow meter in between the injection point and the sample tap/membrane
chamber to provide further mixing. Figure 2-2 shows the injection point and feed sample tap on
the pilot unit.
-------
Figure 2-1 Siemens Memcor CMF-S pilot unit.
-------
Figure 2-2. Challenge organism injection point and feed sample tap on pilot unit.
-------
Chapter 3
Methods and Procedures
3.1 Introduction
The challenge tests were conducted in November of 2008. The tests followed the procedures
described in the Test/QA Plan for the Microbial Seeding Challenge Study of the Siemens Memcor
L10V, L20V, andSlOV Ultrafiltration Modules. The challenge protocol was adapted from the
ETVProtocolfor Equipment Verification Testing for Physical Removal of Microbiological and
Particulate Contaminants., and the USEPA Membrane Filtration Guidance Manual (MFGM).
Note that the MFGM references the ETV protocol as an acceptable protocol for testing
membrane products according the to the USEPA requirements. The test/QA plan is included
with this report as Appendix A.
3.2 Challenge Organisms
The S10V modules were tested for removal of microorganisms using the MS-2 coliphage virus,
and endospores of the bacteria Bacillus atrophaeus (American Type Culture Collection, ATCC
number 9372, deposited as Bacillus subtilis var. niger). B. atrophaeus was used as a surrogate
for Cryptosporidium parvum and other protozoan oocysts. The strain of B. atrophaeus used for
testing yields orange colonies with a distinctive morphology on trypicase soy agar (TSA), so it
can be distinguished from wild-type endospores that could be present as contamination. B.
atrophaeus endospores are ellipsoidal (football shaped), with an average diameter of 0.8 jim, and
an average length of 1.8 |im. The LT2ESWTR allows the use of a surrogate for C. parvum for
challenge testing to obtain C. parvum removal credits, provided the surrogate is conservative.
The suitability of using B. atrophaeus as a surrogate for C. parvum was demonstrated in the ETV
verification testing of the Siemens L10V module. For that verification test, no C. parvum was
detected in the filtrate samples for any of the five different modules tested, but B. atrophaeus
was detected in the filtrate samples for three of the five modules, albeit at less than 1.0 logio per
100 mL. See Appendix B for a discussion of the suitability of this surrogate, and presentation of
the L10V B. atrophaeus and C. parvum removal data.
Virus removal testing was conducted using MS-2 for possible virus removal credits. MS-2 is
considered a suitable surrogate for pathogenic viruses because of its small size, at 24 nanometers
in diameter.
The challenge organism suspensions were injected into the feed water stream at a sufficient rate
to achieve the following target concentrations:
• MS-2 - IxlO4 to IxlO5 plaque forming units per milliliter(PFU/mL); and
• B. atrophaeus - IxlO6 to 5xl06 colony forming units (CPU) per lOOmL.
The MFGM calls for the maximum challenge concentration to be 6.5 logic above the organism's
detection limit (3.16x106). The goal for the B. atrophaeus challenges was to be able to measure
log reductions greater than six, so it was necessary to set the upper bound of the target range at
-------
higher than 3.16xl06 CFU/100 mL to ensure that greater than IxlO6 CFU/100 mL were
measured in the feed samples.
The MS-2 stock suspension was purchased from Biological Consulting Services of North
Florida, Inc. B. atrophaeus was purchased from Presque Isle Cultures.
3.3 UF Module Integrity Tests
Before and after each challenge test, each module was subjected to a two minute pressure decay
test using the program in the pilot unit's PLC. Siemens defined a passing pressure decay test as
less than or equal to 1.5 psig per minute (min). The PLC gives a warning message if this decay
rate is exceeded.
3.4 Test Water Composition
Local tap water was treated by carbon filtration, reverse osmosis, ultraviolet disinfection, and
deionization to make the base water for the tests. The base water has the following quality
control (QC) requirements for use in the NSF testing laboratory:
• Conductivity <2 microsiemens (|J,S) per centimeter (cm) at 25°C;
• Total organic carbon <100 micrograms (|j,g) per L;
• Total chlorine <0.05 milligrams (mg) per L; and
• Heterotrophic bacteria plate count <100 CFU/mL.
Of the above parameters, only total chlorine was measured specifically for this verification. The
other parameters are measured periodically by NSF as part of the internal quality assurance
(QA)/QC program for test water quality.
A 4,000-gallon water supply tank was filled with the base water, and sodium bicarbonate was
added in sufficient quantity to provide alkalinity at a target of 100 ± 10 mg/L as calcium
carbonate. The pH was then lowered with hydrochloric acid to a target range of 7.5 ± 0.5.
Feed samples were collected prior to each challenge period for analysis of total chlorine,
alkalinity, pH, temperature, total dissolved solids, and turbidity. These samples were collected
prior to addition of the challenge organism.
3.5 Challenge Test Procedure
The pilot unit holds four modules, but each module was tested separately, as discussed above in
Section 2.3. The target flux for membrane operation was 80 gallons per square foot per day
(gfd) at 20°C, which, for the L20V, equals a flow rate of 16.7 gallons per minute (gpm).
The modules were "brand new" when challenged. There was no seasoning period, or other
period of operation prior to the tests to allow any sort of a cake layer to build up. Testing new
modules represented a worse case field operation scenario.
Separate challenge tests were conducted for each challenge organism, so each module was tested
twice. Each module was installed in the membrane chamber, and then the test engineer started
-------
operation of the pilot unit and allowed the PLC to run through a start-up sequence of operations.
Once normal filtration had started, the engineer started a pressure decay test. After the pressure
decay test was complete, the normal filtration mode resumed. At this time, the engineer adjusted
the flow rate to 16.7 gpm if necessary, and collected a flush sample from the filtrate sample tap.
The duration of each microbial challenge test was 30 minutes. Feed and filtrate samples were
collected for challenge organism enumeration after three minutes of operation, after 15 minutes
of operation, and after 30 minutes of operation. The challenge organisms were intermittently
injected into the feed stream for five-minute periods using a peristaltic pump at each sampling
point. The injection point was downstream of the pilot unit's feed tank, as shown in Figure 2-2.
During each injection period, the challenge organism was fed to the feed stream for at least 3
minutes prior to collection of the feed and filtrate samples during the fourth and/or fifth minutes.
At the end of each challenge test, a second pressure decay test was conducted to confirm
membrane integrity.
The MFGM suggests that feed and filtrate samples not be collected until at least three hold-up
volumes of water containing the challenge organism have passed through the membrane, to
establish equilibrium (equilibrium volume). The hold-up volume is defined as the "unfiltered
test solution volume that would remain in the system on the feed side of the membrane at the end
of the test." Siemens has calculated the hold-up volume of the Memcor XP pilot unit as 40
gallons, not including the unit's feed tank. The flow rates measured during ETV testing ranged
from 16.70 to 16.96 gpm, so only approximately 50 gallons of the spiked test solution passed
through the membrane modules before sample collection began. This volume was less than the
equilibrium volume of 120 gallons, but the MS-2 filtrate counts suggest that the membranes were
being subjected to the full challenge concentration when the filtrate samples were collected. The
feed samples were collected upstream from the membrane holding chamber, so they are not
indicative of the challenge concentration in the membrane chamber after 3 minutes of injection.
However, most of the MS-2 filtrate counts for the S10V challenges were above IxlO3 PFU/mL.
These filtrate counts were similar to those measured from the ETV challenge tests of the
Siemens L10V and L20V membranes, which use the same UF fibers. So, the fact that the S10V
filtrate counts were similar to those from the L10V and L20V tests indirectly indicates that the
S10V cartridges were exposed to adequate MS-2 challenge concentrations after only 3 minutes
of injection.
3.6 Analytical Methods
A list of laboratory analytical methods can be found in Table 3.1. All samples for MS-2 and B.
atrophaeus and were analyzed in triplicate.
The following are the analytical instruments used for water quality measurements:
• Alkalinity - SmartChem Discrete Analyzer;
• pH - Orion EA 940 pH/ISE meter;
• Temperature - Fluke 51 II digital thermometer;
• Total Chlorine - Hach DR/2010 spectrophotometer using AccuVac vials; and
• Turbidity - Hach 21 OOP turbidimeter.
-------
Table 3-1 Analytical Methods for Laboratory Analyses
Parameter
Alkalinity (total, as CaCO3)
pH
Total Dissolved Solids (TDS)
Total Chlorine
Turbidity
MS-2
B. atrophaeus
Method
USEPA310.2
SM2 4500-H+
SM 2540 C
SM 4500-C1 G
SM2130
NSF 555
SM92186
NSF
Reporting
Limit
5mg/L
NA
5mg/L
0.05 mg/L
0.1 NTU4
1 PFU/mL
1 CFU/100 mL
Lab
Accuracy
(% Recovery)
90-110
NA
90-110
90-110
95-105
—
Lab
Precision
(o/oRPD1)
<13
<10
<10
<10
—
Hold Time
14 days
none3
7 days
none3
none3
30 hours
30 hours
(1) RPD = Relative Percent Deviation
(2) SM = Standard Methods
(3) Immediate analysis required
(4) NTU = Nephelometric Turbidity Unit
(5) Method published in NSF/ANSI Standard 55 - Ultraviolet Microbiological Water Treatment Systems. Method is similar to
EPA Method 1601.
(6) TSA was substituted for nutrient agar in SM 9218 so that the challenge endospores could be distinguished from wild-type
endospores. TSA gives orange colonies with a distinctive morphology.
10
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Chapter 4
Results and Discussion
The challenge tests were conducted from November 10, 2008 to November 14, 2008. One
module was tested per day, with separate challenge tests for MS-2 and B. atrophaeus.
For presentation of the challenge organism data in this chapter, the observed triplicate counts
were averaged by calculating geometric means, as suggested for microbial enumeration data in
SM 9020. The mean counts were also logic transformed for the purpose of calculating log
removal values (LRV). Samples with no organisms found were treated as 1 per unit volume for
the purpose of calculating the means, unless all three triplicate counts were non-detect for the
organism. The triplicate counts for each sample are presented in Appendix C.
The LT2ESWTR and MFGM specify that an LRV for the test (LRVc.TEsx) be calculated for each
module tested, and that the LRV for each module are then combined to yield a single LRVc-xEsx
for the product. If fewer than 20 modules are tested, as was the case for this verification, the
LRVc-xEsx is simply the lowest LRV for the individual modules. However, the rule does not
specify a method to calculate LRVC-xEsx for each module. Suggested options in the MFGM
include:
• Calculate a LRV for each feed/filtrate sample pair, calculate the average of the LRV;
• Average all of the feed and filtrate counts, and then calculate a single LRV for the
module; or
• Calculate a LRV for each feed/filtrate sample pair, select the LRV for the module as the
lowest (most conservative of the three options).
In this section, all three approaches will be used to calculate the LRV for each module. Note the
LT2ESWTR and MFGM do not specify whether the averages should be calculated as the
arithmetic mean or geometric mean. Since the triplicate counts were averaged by calculating
geometric means, so too do the LRV calculations use geometric mean.
4.1 Pressure Decay Test Results
The pre-test and post-test pressure decay test results are presented in Table 4-1. All pressure
decay rates were 0.6 or 0.7 psig/min, indicating that there were no membrane integrity issues
during the tests.
Table 4-1. Pressure Decay Data
Module #
Module 1
Module 2
Module 3
Module 4
Module 5
MS-2 Pressure Decay Data (psig/min)
Pre-Test
0.60
0.70
0.60
0.70
0.60
Post-Test
0.60
0.70
0.70
0.70
0.70
B. atrophaeus Pressure Decay Data (psig/min)
Pre-Test
0.60
0.70
0.70
0.70
0.70
Post-Test
0.60
0.70
0.70
0.70
0.70
11
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4.2 B. atrophaeus Challenge Tests
The B. atrophaeus challenge results are displayed in Table 4-2. All mean feed counts exceeded
the target concentration of IxlO6 CFU/100 mL. The B. atrophaeus challenge results are
displayed in Table 4-5. All mean feed counts exceeded the target concentration of IxlO6
CFU/100 mL. The LT2ESWTR indicates a maximum challenge concentration to achieve a
reduction of 6.5 logio (3.16xl06 CFU/100 mL), so that the maximum LRVc-xEsx awarded to a
membrane product is 6.5 logic. The B. atrophaeus feed concentrations for these tests ranged
from 3.6xl07 to 6.IxlO7 CFU/100 mL. This takes into account the expected percent recovery of
the challenge organism, which is typically less than 100%.
B. atrophaeus endospores were found in the filtrate samples for all modules except Module 1,
but at concentrations of 10 CFU/100 mL or less. One endospore was found in the flush samples
for Modules 4 and 5. The modules were tested in order from 1 to 5, so the fact that an endospore
was found in each of the Module 4 and 5 flush samples indicates that perhaps the pilot unit
became contaminated during the module change-outs. Contamination of the pilot unit is also
evident by the MS-2 flush sample counts presented later in this chapter.
Note that the Module 1 feed samples exceeded the 24-hour holding time. The samples had to be
reprocessed due to laboratory error, and the reprocessing did not occur until the samples were
eight days old. The Module 1 counts were in the same range as the other feed counts, indicating
that the samples were not adversely affected during the holding period. This was likely because
the challenge organism was an environmentally stable endospore that does not die off because it
is not in a vegetative state.
For the S10V B. atrophaeus challenges, all LRV are above 6.5, no matter which of the
calculation methods is used. The LT2ESWTR specifies that the maximum possible LRVc-xEsx
awarded to a membrane product is 6.5 logic, but the LRV above 6.5 are still presented here.
4.2.1 Choosing LRVc-xEsx from the Averages of the Individual LRV Calculations
In Table 4-2, the LRV numbers in the "Overall Mean" rows are the geometric mean calculations
of the individual sample point LRV for each module. Using this approach, the lowest LRV, and
thus the LRVc-xEsx, is 7.10 for Module 3.
4.2.2 LRVc-xEsx Calculated from the Mean Feed and Filtrate Counts
Using this approach, log values need to be calculated for each overall mean feed and filtrate
count. In most cases these log values will be equal to the overall mean log values presented in
Table 4-2 as the mean of the individual logio values. However, in some instances, the log of the
overall mean feed or filtrate count will differ slightly from that calculated from the individual log
values. The log transformations of the overall mean feed and filtrate counts are presented in
Table 4-3. Under this approach, the LRVC-xEsx is 7.13, from Module 3.
12
-------
4.2.3 Choosing LRVC-xEsx from the Individual Sample Point LRV Calculations
In Table 4-2, the LRV for the feed and filtrate pair at each sample point are given in the last
column of the table. The lowest individual LRV for each module are listed in Table 4-4. Under
this approach, the LRVc-xEsx is 6.62, from Module 3.
Table 4-2. B. atrophaeus Challenge Results
Module 1
Module 2
Module 3
Module 4
Module 5
Sample
Point
Flush
3 Minutes
15 Minutes
30 Minutes
Overall Mean
Flush
3 Minutes
15 Minutes
30 Minutes
Overall Mean
Flush
3 Minutes
15 Minutes
30 Minutes
Overall Mean
Flush
3 Minutes
15 Minutes
30 Minutes
Overall Mean
Flush
3 Minutes
15 Minutes
30 Minutes
Overall Mean
Feed
Geometric Mean
(CFU/100 mL)
—
S.lxlO7
5.8xl07
4.6xl07
5.1xl07
—
3.7xl07
4.1xl07
6.1xl07
4.5xl07
—
4.3xl07
3.8xl07
4.2xl07
4.1xl07
—
5.3xl07
3.6xl07
4.2xl07
4.3xl07
—
5.5xl07
5.7xl07
6.0xl07
5.7xl07
Logio
—
7.71
7.76
7.66
7.71
—
7.57
7.61
7.79
7.66
—
7.63
7.58
7.62
7.61
—
7.72
7.56
7.62
7.63
—
7.74
7.76
7.78
7.76
Filtrate
Geometric Mean
(CFU/100 mL)
<1
<1
<1
<1
<1
<1
3
<1
2
2
<1
1
3
10
3
1
<1
2
1
1
1
2
9
2
3
Logio
—
0.0
0.0
0.0
0.0
—
0.48
0.0
0.30
0.26
—
0.0
0.48
1.00
0.49
—
0.0
0.30
0.0
0.0
—
0.30
0.95
0.30
0.44
LRV
—
7.71
7.76
7.66
7.71
7.09
7.61
7.49
7.39
7.63
7.10
6.62
7.10
7.72
7.26
7.62
7.53
7.44
6.81
7.48
7.24
Table 4-3. B. atrophaeus LRVc-TEsx Calculated from the Mean Feed and Filtrate Counts
Module Number
Module 1
Module 2
Module 3
Module 4
Module 5
Feed
Geometric Mean
(CFU/100 mL)
5.1xl07
4.5xl07
4.1xl07
4.3xl07
5.7xl07
Log10
7.71
7.66
7.61
7.63
7.76
Filtrate
Geometric Mean
(CFU/100 mL)
<1
2
o
J
1
o
J
Log10
0.0
0.30
0.48
0.0
0.48
LRV
7.71
7.36
7.13
7.63
7.28
13
-------
Table 4-4. B. atrophaeus LRVc-xEsx from Individual LRV
Module Number
Module 1
Module 2
Module 3
Module 4
Module 5
LRVc-TEST
7.66
7.09
6.62
7.26
6.81
4.3 MS-2 Challenge Tests
Table 4-5 presents the MS-2 challenge data. All mean feed counts exceeded the target of IxlO4
PFU/mL. The maximum observed overall mean filtrate count was 6.3xl03 PFU/mL for Module
1. The highest individual filtrate count was 9.3xl03 PFU/mL, from the Module 1 30-minute
sample. Many MS-2 particles were found in the flush samples for all modules but Module 1.
However, Module 1 also had the highest mean filtrate count and highest individual filtrate
sample count. Therefore, the filtrate side contamination did not appear to impact the LRVc-xEsx
for MS-2.
4.3.1 Choosing LRVc-xEsx from the Averages of the Individual LRV Calculations
In Table 4-5, the LRV numbers in the "Overall Mean" rows are the geometric mean calculations
of the individual sample point LRV for each module. Using this approach, the lowest LRV, and
thus the LRVc-xEsx, is 2.98 for Module 1.
4.3.2 LRVc-xEsx Calculated from the Mean Feed and Filtrate Counts
Using this approach, each overall mean feed and filtrate count needs to be log transformed. In
most cases these log values will be equal to the overall mean log values presented in Table 4-5 as
the mean of the individual logio values. However, in some instances, the log of the overall mean
feed or filtrate count will differ slightly from that calculated from the individual log values. The
log transformations of the overall mean feed and filtrate counts are presented in Table 4-6. The
LRVc-xEsx is 3.00, from Module 1.
4.3.3 Choosing LRVc-xEsx from the Individual Sample Point LRV Calculations
In Table 4-5, the LRV for the feed and filtrate pair at each sample point are given in the last
column of the table. The lowest individual LRV for each module are listed in Table 4-7. Under
this approach, the LRVc-xEsx is 2.57, from Module 1.
14
-------
Table 4-5. MS-2 Challenge Results
Module 1
Module 2
Module 3
Module 4
Module 5
Sample
Point
Flush
3 Minutes
15 Minutes
30 Minutes
Overall Mean
Flush
3 Minutes
15 Minutes
30 Minutes
Overall Mean
Flush
3 Minutes
15 Minutes
30 Minutes
Overall Mean
Flush
3 Minutes
15 Minutes
30 Minutes
Overall Mean
Flush
3 Minutes
15 Minutes
30 Minutes
Overall Mean
Feed
Geometric Mean
(PFU/mL)
—
7.9xl06
9.0xl06
3.5xl06
6.3xl06
—
4.6xl06
3.3xl06
3.5xl06
3.8xl06
—
1.65xl06
1.67xl06
3.1xl06
2.0xl06
—
4.4xl06
3.5xl06
3.6xl06
3.8xl06
—
1.42xl06
1.50xl06
1.59xl06
1.50xl06
Log10
—
6.90
6.95
6.54
6.79
—
6.66
6.52
6.54
6.57
—
6.22
6.22
6.49
6.31
—
6.64
6.54
6.56
6.58
—
6.15
6.18
6.20
6.18
Filtrate
Geometric Mean
(PFU/mL)
<1
5.9xl03
4.5xl03
9.3xl03
6.3xl03
121
1.84xl03
2.7xl03
2.8xl03
2.4xl03
317
680
1.26xl03
1.87xl03
1.2xl03
335
1.39xl03
2.9xl03
4.2xl03
2.6xl03
12
340
310
390
350
Log10
—
3.77
3.65
3.97
3.79
—
3.26
3.43
3.45
3.38
—
2.83
3.10
3.27
3.06
—
3.14
3.46
3.62
3.40
—
2.53
2.49
2.59
2.54
LRV
—
3.13
3.30
2.57
2.98
3.40
3.09
3.09
3.19
3.39
3.12
3.22
3.24
3.50
3.08
2.94
3.16
3.62
3.69
3.61
3.64
Table 4-6. MS-2 LRVC-TEST Calculated from the Mean Feed and Filtrate Counts
Module Number
Module 1
Module 2
Module 3
Module 4
Module 5
Feed
Geometric Mean
(PFU/mL)
6.3xl06
3.8xl06
2.0xl06
3.8xl06
1.50xl06
Log10
6.80
6.58
6.30
6.58
6.18
Filtrate
Geometric Mean
(PFU/mL)
6.3xl03
2.4xl03
1.2xl03
2.6xl03
350
Log10
3.80
3.38
3.07
3.41
2.54
LRV
3.00
3.20
3.23
3.17
3.64
Table 4-7. MS-2 LRVC-TEsx from Individual LRV
Module Number
Module 1
Module 2
Module 3
Module 4
Module 5
LJvVc_xEST
2.57
3.09
3.12
2.94
3.61
15
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4.4 Operational Data and Water Quality Data for All Challenges
The pilot unit operational data is presented in Table 4-8. The filtrate flow rate recordings ranged
from 16.70 to 16.96 gpm. The target flow rate for the tests was 16.7 gpm, so all tests were
conducted at, or slightly above, the target flow rate. Note that the flow rate was controlled using
the pilot unit's PLC, which was receiving flow rate data from the internal flow meter. However,
the flow rate measurements were taken on the filtrate line outside the pilot unit using a laboratory
flow meter that had been calibrated prior to the start of testing. The TMP was calculated by the
pilot unit PLC using the pressure transducers on the pilot unit. These transducers were not
calibrated prior to testing. Siemens' maximum trans-membrane pressure of 17.4 psig was not
exceeded at any time during testing.
Table 4-8. Operation Data
Module #
Date
Filtrate Flow Rate
(gpm)
OMin.
30 Min.
Flux
(gfd)
OMin
30 Min
TMP
(psig)
OMin.
30 Min.
B. atrophaeus Challenges
Module 1
Module 2
Module 3
Module 4
Module 5
11/10/08
11/11/08
11/12/08
11/13/08
11/14/08
16.86
16.90
16.85
16.86
16.73
16.77
16.80
16.78
16.91
16.78
80.9
81.1
80.9
80.9
80.3
80.5
80.6
80.5
81.2
80.5
9.7
8.1
7.6
8.8
8.6
9.8
8.8
7.8
8.9
8.7
MS-2 Challenges
Module 1
Module 2
Module 3
Module 4
Module 5
11/10/08
11/11/08
11/12/08
11/13/08
11/14/08
16.70
16.91
16.96
16.77
16.78
16.73
16.78
16.73
16.78
16.78
80.2
81.2
81.4
80.5
80.5
80.3
80.5
80.3
80.5
80.5
9.2
7.7
7.4
8.6
8.6
9.5
8.4
7.8
8.9
9.0
The water chemistry data is displayed in Table 4-9. Of the water quality parameters reported,
only alkalinity and pH had target ranges specified in the test/QA plan. All alkalinity and pH
measurements were within the targeted ranges.
Table 4-9. Water Chemistry Data
Module #
Date
Alkalinity
(mg/L
CaC03)
PH
Temp. (°C)
Total
Chlorine
(mg/L)
TDS (mg/L)
Turbidity
(NTU)
B. atrophaeus Challenges
Module 1
Module 2
Module 3
Module 4
Module 5
11/10/08
11/11/08
11/12/08
11/13/08
11/14/08
100
97
88
90
100
7.86
7.77
7.84
7.85
7.74
19.8
22.8
22.0
22.0
22.3
O.05
O.05
O.05
O.05
O.05
130
120
100
100
110
0.44
0.49
0.47
0.42
0.20
MS-2 Challenges
Module 1
Module 2
Module 3
Module 4
Module 5
11/10/08
11/11/08
11/12/08
11/13/08
11/14/08
100
98
95
90
94
7.79
7.78
7.73
7.75
7.70
20.0
23.2
21.9
21.5
22.3.
O.05
O.05
O.05
O.05
O.05
130
120
99
99
110
0.41
0.51
0.36
0.45
0.25
16
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Chapter 5
Quality Assurance/Quality Control
5.1 Introduction
An important aspect of verification testing is the QA/QC procedures and requirements. Careful
adherence to the procedures ensured that the data presented in this report was of sound quality,
defensible, and representative of the equipment performance. The primary areas of evaluation
were representativeness, accuracy, precision, and completeness.
Because this ETV was conducted at the NSF testing lab, all laboratory activities were conducted
in accordance with the provisions of the NSF International Laboratories Quality Assurance
Manual.
5.2 Test Procedure QA/QC
NSF testing laboratory staff conducted the tests by following a USEPA-approved test/Q A plan
created specifically for this verification (Appendix A). NSF QA Department staff performed an
audit during testing to ensure the proper procedures were followed. The audit yielded no
significant findings.
5.3 Sample Handling
All samples analyzed by the NSF Chemistry and Microbiology Laboratories were labeled with
unique identification numbers. All samples, except the Module 1 feed samples from the B.
atrophaeus challenge, were analyzed within the allowable holding times. The Module 1 feed
samples had to be reprocessed due to laboratory error when the samples were eight days old.
5.4 Chemistry Laboratory QA/QC
The calibrations of all analytical instruments and the analyses of all parameters complied with
the QA/QC provisions of the NSF International Laboratories Quality Assurance Manual.
The NSF QA/QC requirements are all compliant with those given in the USEPA method or
Standard Method for the parameter. Also, every analytical method has an NSF standard
operating procedure.
5.5 Microbiology Laboratory QA/QC
5.5.1 Growth Media Positive Controls
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.
17
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5.5.2 Negative Controls
For each sample batch processed, an unused membrane filter and a blank with 100 mL of
buffered, sterilized dilution water was 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.
5.6 Documentation
All laboratory activities were documented using specially prepared laboratory bench sheets and
NSF laboratory reports. Data from the bench sheets and laboratory reports were entered into
Microsoft™ Excel® spreadsheets. These spreadsheets were used to calculate the geometric
means and logio reductions. One hundred percent of the data entered into the spreadsheets was
checked by a reviewer to confirm all data and calculations were correct.
5.7 Data Review
NSF QA/QC staff reviewed the raw data records for compliance with QA/QC requirements. As
required in the ETV Quality Management Plan, NSF ETV staff checked at least 10% of the data
in the NSF laboratory reports against the lab bench sheets.
5.8 Data Quality Indicators
The quality of data generated for this ETV is established through four indicators of data quality:
representativeness, accuracy, precision, and completeness.
5.8.1 Representativeness
Representativeness refers to the degree to which the data accurately and precisely represent the
expected performance of the UF membranes under normal use conditions. The membrane
modules were tested in a Siemens pilot unit, at the flux specified by Siemens.
Representativeness was ensured by consistent execution of the test protocol for each challenge,
including timing of sample collection, sampling procedures, and sample preservation.
Representativeness was also ensured by using each analytical method at its optimum capability
to provide results that represent the most accurate and precise measurement it is capable of
achieving.
5.8.2 Accuracy
Accuracy was quantified as the percent recovery of the parameter in a sample of known quantity.
Accuracy was measured through use of both matrix spikes of a known quantity and certified
standards during calibration of an instrument.
The following equation was used to calculate percent recovery:
Percent ReCOVery = 100 X [(Xknown - Xmeasured)/Xknown]
where: Xkn0wn = known concentration of the measured parameter
= measured concentration of parameter
18
-------
Accuracy of the benchtop chlorine, pH, and turbidity meters was checked daily during the
calibration procedures using certified check standards. Alkalinity and TDS were analyzed in
batches. Certified QC standards and/or matrix spikes were run with each batch.
The percent recoveries of all matrix spikes and standards were within the allowable limits for all
analytical methods.
5.8.3 Precision
Precision refers to the degree of mutual agreement among individual measurements and provides
an estimate of random error. The NSF laboratory analyzes at least one out of every ten samples
in duplicate for water chemistry parameters. However, note that since the samples from the tests
described herein were analyzed in batches with other samples, the laboratory did not perform
duplicate analysis on 10% of the samples from this project.
The NSF laboratory measures precision by calculating RPD using the following formula:
RPD =
x200
where:
S1 = sample analysis result; and
S2 = sample duplicate analysis result.
All RPD were within NSF's established allowable limits for each parameter.
5.8.4 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, as presented in Table 5-1.
Table 5-1. Completeness Requirements
Number of Samples per Parameter and/or Method
0-10
11-50
>50
Percent Completeness
80%
90%
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.
19
-------
All planned samples were collected for challenge organism and water chemistry analysis, and all
planned operational data readings were collected. This gives a completeness of 100% for all
parameters.
20
-------
Chapter 6
References
APHA, AWWA, and WEF (2005). Standard Methods for the Examination of Water and
Wastewater, 21st Edition.
NSF International (2007). NSF/ANSI Standard 55 - Ultraviolet Microbiological Water
Treatment Systems.
USEPA (2005). Membrane Filtration Guidance Manual (EPA 815-R-06-009).
USEPA and NSF International (2005). ETVProtocolfor Equipment Verification Testing for
Physical Removal of Microbiological and Paniculate Contaminants
21
-------
Appendix A
Test/Quality Assurance Project Plan
Please contact Bruce Bartley of NSF International at bartley@nsf.org, or 734-769-5148 for a
copy of the test/quality assurance project plan.
A-l
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Appendix B
Bacillus Endospores as a Surrogate for Cryptosporidium parvum
The EPA LT2ESWTR allows the use of a surrogate for Cryptosporidium parvum, provided the
surrogate is conservative. The EPA MFGM specifically discusses Bacillus subtilis as a
surrogate, but states "Because there is limited data currently available regarding the use of
Bacillus subtilis in membrane challenge studies, a characterization of this organism would be
necessary to determine whether it could be used as a Cryptosporidium surrogate..." The MFGM
also states "Based on the size.. .Bacillus subtilis could potentially be considered a conservative
surrogate.. .pending a comparison of other characteristics (e.g., shape, surface charge, etc.)..."
This appendix discusses supporting evidence for the use of Bacillus endospores as a surrogate for
C. parvum.
1. Organism Size and Shape
C. parvum is spherical in shape, while Bacillus endospores are ellipsoidal in shape (football
shaped). C. parvum has a diameter of 4-6 jim. Bacillus endospores are approximately 0.8 jim in
diameter, and 1.8 jim in length. Therefore, Bacillus endospores are a conservative surrogate for
C. parvum, no matter what the orientation of the endospore is when it impacts the test
membrane.
Baltus et. al. (2008) studied membrane rejection of bacteria and viruses with different length vs.
diameter aspect ratios. They theorized, based on a transport model for rod-shaped particles, that
rejection would improve as the aspect ratio (length vs. diameter) increased for a fixed particle
volume. However, their experimental results contradicted this, with similar rejection rates for
particles with a range of aspect ratios. The model assumed that particles would impact the
membrane with equal frequency for all particle orientations. They theorize that instead, an end-
on orientation was favored for transport of the particles in the water stream. They concluded that
microorganism removal by membranes could be conservatively estimated using only the rod
diameter in transport models. These findings add an additional safety factor to using Bacillus
endospores as a surrogate for C. parvum.
2. Electrophoretic Mobility and Isoelectric Point
A suitable surrogate should have a surface charge similar to C. parvum, as measured through the
isoelectric point and electrophoretic mobility (EPM). The isoelectric point is the pH at which the
particle has a neutral surface charge in an aqueous environment. Below this point the particle
has a net positive charge, above it a net negative charge. Many studies have pegged the
isoelectric point of C. parvum between pH values of 2 and 4, thus it would have a negative
surface charge in the neutral pH range. The isoelectric point can be found by measuring the
EPM of the particle at various pH values. The pH where the EPM is zero is classified as the
isoelectric point.
Lytle et. al. (2002) measured the EPM of both C. parvum and B. subtilis endospores in solutions
of increasing buffer concentration (0.915 millimolar, mM, 9.15 mM, and 91.5 mM KH2PO4).
They found that increasing the buffer concentration also increases the EPM toward a positive
B-l
-------
value. The buffer concentration of the test water for the Siemens tests was approximately 1 mM.
Therefore, the 0.915 mM data from this study should be the most accurate representation of the
C. parvum and B. subtilis EPM for the ETV tests. In 0.915 mM solutions at pH values between
7 and 8, they observed EPM of approximately -2.2 to -2.6 jim cm V"1 s"1 for C. parvum, and -1.9
to -2.2 |im cm V'V1 for B. subtilis. For B. subtilis, the researchers did not measure an isoelectric
point at any buffer concentration. For C. parvum, they did find an isoelectric point at a pH
around 2.5, but only for the 9.15 mM solution. For both organisms, the 0.915 mM solution
generally gave lower (more negative) EPM values than the solutions with higher buffering
capacity.
3. Aggregation
The NSF Microbiology Laboratory microscopically examined a sample of the B. atrophaeus
stock solutions purchased for the tests. The sample was suspended in sterile, buffered, deionized
water and stirred at moderate speed for 15 minutes. The estimated cell density was IxlO9
CFU/100 mL, which is more than 10 times higher than the suspensions injected into the pilot
units to challenge the UF membranes. Figure 1 is a photograph of the B. atrophaeus endospores
in the sample. The magnification is lOOOx oil immersion with differential interference contrast
microscopy. No evidence of endospore aggregation was found.
Figure B-l. Mono-dispersed B. atrophaeus endospores used for challenge tests.
B-2
-------
4. ETV Test Data Comparing Bacillus endospores and C. parvum
During the Siemens L10V verification test, the membranes were challenged with both B.
atrophaeus and C. parvum so that removal of both organisms could be compared. No C. parvum
was detected in the filtrate samples for any of the five L10V modules tested, but B. atrophaeus
was detected in the filtrate samples for three of the five modules, albeit at less than 1.0 logio per
100 mL. The test data is presented in Tables B-l and B-2.
Table B-l. Siemens L10V C. parvum Challenge Results
Module
Number
Module 1
Module 2
Module 3
Module 4
Module 5
Sample Point
3 Minutes
1 5 Minutes
30 Minutes
Overall Mean
3 Minutes
1 5 Minutes
30 Minutes
Overall Mean
3 Minutes
1 5 Minutes
30 Minutes
Overall Mean
3 Minutes
1 5 Minutes
30 Minutes
Overall Mean
3 Minutes
1 5 Minutes
30 Minutes
Overall Mean
Feed
Geometric Mean
(Oocysts/L)
e.oxio'
7.5xl05
5.7x10'
6.4x10'
3.2xl05
5.8xl05
5.8xl05
4.8x10'
4.8xl05
5.8xl05
4.1xl05
4.9xl05
4.8xl05
4.7x10'
4.7x10'
4.7x10'
5.2x10'
4.7x10'
5.1x10'
5.0x10'
Log™
5.78
5.88
5.76
5.81
5.51
5.76
5.76
5.68
5.68
5.76
5.61
5.68
5.68
5.67
5.67
5.67
5.71
5.67
5.71
5.70
Filtrate
Geometric Mean
(Oocysts/L)
<1
<1
<1
<1
<1
<1
<1
<1
<1
<1
<1
<1
<1
<1
<1
<1
<1
<1
<1
<1
Log™
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
B-3
-------
Table B-2. Siemens L10V B. atrophaeus Challenge Results
Module 1
Module 2
Module 3
Module 4
Module 5
Sample Point
3 Minutes
1 5 Minutes
30 Minutes
Overall Mean
3 Minutes
1 5 Minutes
30 Minutes
Overall Mean
3 Minutes
1 5 Minutes
30 Minutes
Overall Mean
3 Minutes
1 5 Minutes
30 Minutes
Overall Mean
3 Minutes
1 5 Minutes
30 Minutes
Overall Mean
Feed
Geometric Mean
(CFU/100 mL)
l.OxlO7
9.3xl06
9.0x10°
9.4xl06
6.0xl06
7.5x10"
8.1x10"
7.1x10"
9.9x10"
l.OxlO7
9.6x10"
9.8x10"
l.OSxlO7
6.2x10"
9.7x10"
8.7x10"
6.3x10"
7.4x10"
8.0x10"
7.2x10"
Log™
7.00
6.97
6.95
6.97
6.78
6.88
6.91
6.85
7.00
7.00
6.98
6.99
7.03
6.79
6.99
6.94
6.80
6.87
6.90
6.86
Filtrate
Geometric Mean
(CFU/100 mL)
2
1
4
2
<1
3
<1
1
<1
<1
<1
<1
<1
6
2
2
<1
<1
<1
<1
Logio
0.3
0.0
0.6
0.3
0.0
0.5
0.0
0.2
0.0
0.0
0.0
0.0
0.0
0.8
0.3
0.4
0.0
0.0
0.0
0.0
References
Baltus, R. E., A. R. Badireddy, W. Xu, and S. Chellam (2009). Analysis of Configurational
Effects on Hindered Convection of Nonspherical Bacteria and Viruses across Microfiltration
Membranes. Industrial and Engineering Chemistry Research. In press.
Brush, C. F., M. F. Walter, L. J. Anguish, and W. C. Ghiorse (1998). Influence of Pretreatment
and Experimental Conditions on Electrophoretic Mobility and Hydrophobicity of
Cryptosporidium parvum Oocysts. Applied and Environmental Microbiology. 64: 4439-4445.
Butkus, M. A., J. T. Bays, and M. P. Labare (2003). Influence of Surface Characteristics on the
Stability of Cryptosporidium parvum Oocysts. Applied and Environmental Microbiology. 69:
3819-3825.
Lytle, D. A., C. H. Johnson, and E. W. Rice. 2002. A Systematic Comparison of the
Electrokinetic Properties of Environmentally Important Microorganisms in Water. Colloids and
Surfaces B: Biointerfaces. 24: 91-101.
B-4
-------
Appendix C
Challenge Organism Triplicate Counts
Table C-l. B. atrophaeus Triplicate Count Data
Module
Module 1
Module 2
Module 3
Module 4
Module 5
Sample
Flush
3 Minutes
1 5 minutes
30 minutes
Flush
3 Minutes
1 5 minutes
30 minutes
Flush
3 Minutes
1 5 minutes
30 minutes
Flush
3 Minutes
1 5 minutes
30 minutes
Flush
3 Minutes
1 5 minutes
30 minutes
Feed (CFU/mL)
Count 1
—
6.1E+07
5.7E+07
4.7E+07
—
3.8E+07
3.9E+07
5.2E+07
—
4.0E+07
3.3E+07
4.0E+07
—
4.2E+07
3.9E+07
3.2E+07
—
6.3E+07
6.2E+07
4.7E+07
Count 2
—
4.1E+07
5.6E+07
4.2E+07
—
3.2E+07
4.2E+07
6.4E+07
—
4.5E+07
5.1E+07
4.7E+07
—
5.9E+07
3.0E+07
4.5E+07
—
4.9E+07
4.8E+07
6.5E+07
Count 3
—
5.3E+07
6.0E+07
4.9E+07
—
4.0E+07
4.1E+07
6.9E+07
—
4.3E+07
3.2E+07
4.0E+07
—
6.0E+07
4.0E+07
5.0E+07
—
5.3E+07
6.1E+07
7.0E+07
Filtrate (CFU/lOOmL)
Count 1
<1
<1
<1
<1
<1
6
<1
2
<1
2
16
8
1
<1
1
1
1
4
5
3
Count 2
<1
<1
<1
<1
<1
2
<1
2
<1
1
<1
13
<1
<1
<1
1
<1
3
11
1
Count 3
<1
<1
<1
<1
<1
2
<1
1
<1
<1
<1
11
<1
<1
4
1
<1
<1
12
4
Table C-2. MS-2 Triplicate Count Data
Module
Module 1
Module 2
Module 3
Module 4
Module 5
Sample
Flush
3 Minutes
1 5 minutes
30 minutes
Flush
3 Minutes
1 5 minutes
30 minutes
Flush
3 Minutes
1 5 minutes
30 minutes
Flush
3 Minutes
1 5 minutes
30 minutes
Flush
3 Minutes
1 5 minutes
30 minutes
Feed (PFU/mL)
Count 1
—
8.0E+06
4.1E+06
3.4E+06
—
4.8E+06
2.7E+06
3.1E+06
—
1.72E+06
1.75E+06
3.1E+06
—
4.5E+06
3.6E+06
5.7E+06
—
1.23E+06
1.13E+06
1.49E+06
Count 2
—
7.1E+06
4.3E+07
3.1E+06
—
4.2E+06
3.4E+06
3.2E+06
—
1.39E+06
1.81E+06
3.4E+06
—
4.6E+06
4.4E+06
2.7E+06
—
1.41E+06
1.52E+06
1.56E+06
Count 3
—
8.6E+06
4.1E+06
4.2E+06
—
4.9E+06
3.8E+06
4.3E+06
—
1.89E+06
1.48E+06
2.9E+06
—
4.0E+06
2.7E+06
3.0E+06
—
1.65E+06
1.97E+06
1.72E+06
Filtrate (PFU/mL)
Count 1
<1
5600
5500
9600
96
1990
2700
3000
372
590
1160
1920
372
1320
2700
5000
29
400
320
410
Count 2
<1
5600
3800
9100
151
1470
2500
2500
264
820
1230
1810
312
1490
3100
3600
14
330
290
500
Counts
<1
6700
4300
9300
121
2140
2800
2800
324
650
1410
1890
324
1370
3000
4200
4
310
320
290
C-l
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