THE ENVIRONMENTAL TECHNOLOGY VERIFICATION
PROGRAM
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U.S. Environmental Protection Agency
NSF International
ETV Joint Verification Statement
TECHNOLOGY TYPE: ULTRAFILTRATION
APPLICATION: REMOVAL OF MICROBIAL CONTAMINANTS
PRODUCT NAME: MEMCOR® L20V 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 (UF)
module for removal of microbial contaminants under controlled laboratory challenge conditions. The
challenge tests were conducted atNSF'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.
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ABSTRACT
The Siemens Memcor L20V 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. 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 L20V equates to approximately 22.8
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-iEsi) 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
6.89
2.49
Method 2
6.89
2.50
Method 3
6.81
2.22
PRODUCT DESCRIPTION
The Memcor L20V UF membrane module is a member of the Memcor XP line of products. The module
measures 4.7 inches in diameter by 70.9 inches in length. The membrane fibers are made of
polyvinylidene fluoride (PVDF). Water flow through the membrane fibers is outside to inside. 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 L20V 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 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 sodium bicarbonate
NSF 09/31/EPADWCTR
The accompanying notice is an integral part of this verification statement. September 2009
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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 Particulate Contaminants, and the USEPA Membrane Filtration Guidance Manual
(MFGM).
The pilot unit holds three modules, but each module was tested separately. Each module was tested in the
same housing. The other two housings were closed off. The target flux for the tests was 80 gallons per
square foot per day (gfd), which equals a flow rate of 22.8 gallons per minute (gpm) for the L20V
module.
Before and after each challenge test, the modules were 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 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 grab 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 2-1. 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 equilibirum
(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 that
the hold-up volume for the Memcor CP pilot unit with only one membrane cartridge in place is 8 gallons,
not including the unit's feed tank. The microbial challenges were conducted at approximately 22.8 gpm,
so over 68 gallons of spiked feed water passed through the membranes prior to sample collection, well
over the equilibrium volume.
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-TEST 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).
NSF 09/31/EPADWCTR The accompanying notice is an integral part of this verification statement. September 2009
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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 0.08 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 logic
(3.16xl06 CFU/100 mL). The B. atrophaeus feed concentrations for these tests ranged from 6.5xl06 to
1.7xl07 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 logic, but the LRV above
6.5 are still presented here.
No B. atrophaeus endospores were found in any of the filtrate samples for the Modules 1 and 2, but B.
atrophaeus at only 1 CFU/100 mL was found in some of the filtrate samples for Modules 3, 4, and 5.
Endospores were also found in the flush samples for Modules 3 and 4, at 1 and 3 CFU/100 mL,
respectively. Therefore, the observed filtrate counts could be due to low level contamination of the pilot
unit by the challenge organism. Since all filtrate samples were either 1 or <1 CPU, the filtrate log
transformations are all 0.0. This makes the LRV simply a function of the log of the challenge
concentration. The flow rates measured during the B. atrophaeus challenges translated into fluxes
ranging from 79.5 to 80.9 gfd.
Table VS-ii. B. atrophaeus LRV Calculations
Module #
Module 1
Module 2
Module 3
Module 4
Module 5
Method 1
6.89(1)
6.90
6.91
7.00
7.07
Method 2
6.89(1)
6.90
6.91
7.00
7.07
Method 3
6.81(1)
6.89
6.90
6.99
6.97
(1) LRVc-TEsi under these two methods should be capped at 6.5.
MS-2 Reduction
The MS-2 feed concentrations ranged from 2.5xl04 PFU/mL to 7.4xl04 PFU/mL. The LRV for MS-2
reduction are shown in Table VS-iii. The LRVc-TEsi for each method is in bold font. The maximum
individual filtrate count was 212 PFU/mL for Module 2 at start-up. The flow rates measured during the
MS-2 challenges translated into fluxes ranging from 79.2 to 80.6 gfd.
Table VS-iii. MS-2 LRV Calculations
Module #
Module 1
Module 2
Module 3
Module 4
Module 5
Method 1
3.26
2.58
2.49
2.70
2.84
Method 2
3.28
2.58
2.50
2.70
2.84
Method 3
2.84
2.32
2.22
2.39
2.65
NSF 09/31/EPADWCTR
The accompanying notice is an integral part of this verification statement. September 2009
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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 Original signed by Robert Ferguson 11/05/09
Sally Gutierrez Date Robert Ferguson Date
Director Vice President
National Risk Management Research Water Systems
Laboratory NSF International
Office of Research and Development
United States Environmental Protection
Agency
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 09/31/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 09/31/EPADWCTR The accompanying notice is an integral part of this verification statement. September 2009
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