State of California—Health and Human Services Agency
California Department of Public Health
RON CHAPMAN, MD, MPH
Director & State Health Officer
EDMUND G. BROWN JR.
Governor
February 8, 2013
Michael Hank, Geschäftsführer
Seccua Americas
Krummbachstr. 8
86989 Steingaden, Germany
Dear Mr. Hank:
Conditional Acceptance of the SeccuMem Pro 1000 Membrane Module and Application
Notes for Seccua Virex Pro 1000 Ultrafiltration Systems
On behalf of the Water Treatment Committee (WTC) of the California Department of Public
Health (CDPH), Drinking Water Program, I would like to thank you for the opportunity to review
test data from pathogen challenge studies on your ultrafiltration membrane module as outlined
in the report ―Seccua Virex Pro Ultrafiltration Systems,‖ prepared by Seccua GmbH,
Steingaden, Germany, dated July 2012. The Seccua Virex Pro 1000 Ultrafiltration System uses
SeccuMem Pro 1000 membrane modules, pressure-driven polyethersulfone (PES) hollow fibers
with direct flow (dead-end mode), inside-out operation for the filtration of surface water.
Based on the results of testing conducted at the Outdoor Learning Center near Ely, Minnesota
during August and September 2009 and January 2010 (by Shaw Environmental), the WTC has
determined that the SeccuMem Pro 1000 membrane module is approved as an alternative
filtration technology to meet the physical removal requirements of the California Surface Water
Treatment Rule (SWTR) (California Code of Regulations, Title 22, Division 4, Environmental
Health Chapter 17, Article 2, Section 64653(f)), as well as the Federal Long Term 1 and Long
Term 2 Enhanced Surface Water Treatment Rules (LT1ESWTR, LT2ESWTR), for use on any
approved surface source water when used as the core of a complete and well designed,
constructed and operated filtration system. The results from the virus (MS-2 bacteriophage)
and Cryptosporidium surrogate (Bacillus subtilis) challenge tests provided the WTC with
valuable insight on the performance characteristics of the membrane and aided the WTC in its
decision to accept your membrane as an alternative filtration technology.
The WTC hereby accepts the SeccuMem Pro 1000 membrane as an alternative filtration
technology for compliance under the California SWTR, LT1ESWTR and the LT2ESWTR.
In reviewing the data submitted in the technical report, the WTC found that the SeccuMem Pro
1000 Ultrafiltration membrane meets the minimum alternative technology requirements of
demonstrating 2-log Giardia lamblia and 1-log virus removal as set forth in Section 64653(f). As
such, your technology can be used in public water systems in the State of California.
Furthermore, based on the results of tests conducted to remove MS-2 bacteriophage and
Bacillus subtilis, the WTC credits the SeccuMem Pro 1000 Ultrafiltration membrane with the
capability of removing at least 4-log Cryptosporidium and 4-log Giardia lamblia at least 95
percent of the time for treating surface water when operated under the same conditions at which
Drinking Water Technical Operations Section
nd
850 Marina Bay Parkway, Building P, 2 Floor, Richmond, CA 94804
Telephone: (510) 620-3474 Fax: (510) 620-3455
Internet Address: http://www.cdph.ca.gov/programs/Pages/DWP.aspx
Michael Hank
Seccua Americas
February 8, 2013
Page 2
the testing at the Outdoor Learning Center near Ely, Minnesota was conducted. The testing
was performed at a maximum flux rate of 90 L/m2·hr (53 gal/ft2·day) and a maximum
transmembrane pressure (TMP) of 2.5 bars (36 psi) without the use of a coagulant.
Table 1 provides the pathogen removal credit assigned by CDPH to the SeccuMem Pro 1000
Ultrafiltration membrane module and Table 2 presents the operating and quality control values
that the membrane system cannot exceed as a condition of this acceptance.
Table 1 – Pathogen Removal Credit
Target Organism
Giardia lamblia oocyst
Cryptosporidium oocyst
Virus
Removal Credit
4-log 1
4-log
At least 1-log 1,2
1
To adhere to multi-barrier treatment, each plant is required to provide a minimum of 0.5-log inactivation of
Giardia cyst and 4-log inactivation of viruses through disinfection.
2
This membrane was demonstrated to achieve at least 4-log virus removal. However, the routine pressure
decay based test for verifying membrane integrity does not have the resolution to detect changes in virus
removal efficiency. Thus, a minimum of 4-log inactivation of viruses through disinfection is required.
Table 2 – System Operating & Quality Control Parameters
Operating Parameter
Flux
Surface Area
Flow
Upper Control Limit (UCL)1
Maximum Value
90 L/m2·hr (53 gal/ft2·day); inside surface area
8 m2 per module; 16 m2 total; Virex Pro 1000 (2010)
24 L/min (6.34 gpm) per unit; each unit has two
membrane modules
2.5 bars (36 psi)
0.1 NTU based on 95% of monthly measurements;
Not to exceed 0.5 NTU at any time
8.41 mbar/min (0.122 psi/min)
Permeability of a new Membrane2
Membrane Integrity Test (MIT)
Ending Pressure3
400 L/(m2 · hr · TMPbar); 16.3 gal/(ft2 · day · TMPpsi)
≥ 0.99 bar (14.35 psi); θ = 45o
θ = liquid-membrane contact wetting angle
Transmembrane Pressure (TMP)
Turbidity Performance Standards
1
This is the maximum UCL allowed to achieve a log removal value (LRV) > 3.0 log reduction of
2
Cryptosporidium based on worst-case conditions (maximum TMP, minimum Flux rate of 17.06 L/m ·hr (10
2
gal/ft ·day) or 4.54 L/min (1.2 gpm) per membrane unit (two membrane modules)
2
For T = 20 C and membrane area of 16 m . The membrane modules are expected to stabilize over time
at 75% of its initial performance.
3
o
2
To maintain a resolution of 3 µm or less.
Specifications for the Virex Pro 1000 membrane are provided in Table 3 below. A photo of two
Seccua Virex Pro 1000 membrane units is shown on page 4. One of the units has the cover
removed to show the two membrane modules.
Michael Hank
Seccua Americas
February 8, 2013
Page 3
Table 3 – Seccua Virex Pro 1000 Specifications
Specification
Value
Treatment System
Seccua Virex Pro 1000
Membrane Classification
Ultrafiltration
Membrane Element
SeccuMem Pro 1000
Fiber – Dimensions and Construction
Nominal Pore Size
0.008 µm
Absolute Pore Size
0.015 µm
Membrane Material
Modified Polyether-Sulfone (PESM)
Membrane Surface Chemistry
Hydrophilic; Negative Surface Charge
Membrane Type
Hollow Fiber
Membrane Flow Path
Inside-Out
Fiber (OD/ID)
0.90 mm / 0.70 mm
Active Fiber Length
920 mm (36.2 inches)
pH tolerance (cleaning operations)
1.0 – 14.0
Max short-term concentration of free chlorine 200 mg/L
Chlorine Tolerance
200,000 mg/L - hours
Module – Dimensions and Construction
Fibers per Module
3,936
Membrane Area (based on inner diameter)
8 m2 (86 ft2) / module; 16 m2 (172 ft2) / unit
Potting Material
Polyurethane (PU)
Casing Material
Unplasticized polyvinylchloride (uPVC)
Quality Control Release Value (QCRV)
0.5 mbar/min (0.007 psi/min)
Module Dimensions (Dia x L)
110 mm x 980 mm (4.3 in x 38.6 in)
Membrane Unit Weight (no water)
50 Kg (includes two modules and cabinetry);
Membrane Operational Parameters
Filtration Mode
Dead-End
o
Maximum Design Flux at 20 C
90 L/m2·hr (53 gal/ft2·day)
Maximum Design Flow
12 L/min (3.17 gpm) per module
Maximum Inlet Pressure
5 bars (72 psi)
Maximum Transmembrane Pressure
2.5 bars (36 psi)
Membrane Integrity Test (MIT) Parameters
Starting Pressure Decay Test (PDT)
1.59 bars (23.05 psig)
Max backpressure during MIT
0.090 bar (1.3 psi or 36 in)
Membrane Diffusion Rate (@ 10oC)
0.15 mbar/min (0.00218 psi/min) per unit
Pressure Detection Step
25 mbar (0.363 psi)
Potting Depth
40 mm (1.57 in)
Liquid-membrane contact wetting angle (θ)
45o
Capillary constant that describes pore shape 1 (most conservative)
Membrane Hold-up Volume
11.4 liters (3.02 gal) per unit
MIT Holding Time
23 minutes (1,380 seconds)
Volumetric Concentration Factor (VCF)
1 (dead-end-mode of operations)
Michael Hank
Seccua Americas
February 8, 2013
Page 4
Two Virex Pro 1000
UF membrane units
Without cover
Michael Hank
Seccua Americas
February 8, 2013
Page 5
Based on the technical report, it was demonstrated that a MIT can be used as a reliable
performance indicator for the membrane and the calculated Cryptosporidium Log Reduction
Value (LRV) can provide a close estimate of the membrane’s actual performance.
According to the LT2ESWTR, integrity testing has to be conducted at two levels: manufacturing
and installed system. At the manufacturing level, integrity testing is used as a quality assurance
and quality control (QA/QC) tool. Each filter module has to pass a nondestructive performance
test (NDPT) in which a quality control release value (QCRV) is established in accordance with
the performance criteria specified in the rule. This factory-instituted test would ensure the
performance and integrity of the individual filter module shipped. After a membrane system is
installed and put into operation, integrity testing is conducted routinely to ensure a targeted LRV
is being maintained. The manufacturer has specified a QCRV of 0.5 mbar/min (0.007 psi/min)
with a starting Pressure Decay Test (PDT) pressure of 1.59 bars (23.05 psig) for the SeccuMem
Pro 1000 Ultrafiltration membrane modules.
In the event there is a fiber breach in the membrane module that results in a MIT failure, the
module may need to be replaced – there is no protocol for isolating a compromised fiber. The
protocol for determining which module has failed is to randomly remove one module and
replace it with a new module and perform a MIT. If there is a failure in MIT, then swap back
original module and replace other module with the new module and verify with a MIT. The
manufacturer does recommend that both modules be replaced at the same time to ensure both
start with the same permeability and to maintain even flow through both modules.
The Volumetric Concentration Factor (VCF) was assumed to be 1 based on deposition (or
dead-end) mode of hydraulic operations per the EPA LT2 Membrane Filtration Guidance
Manual.
For determining the Minimum Test Pressure (Ptest), the following values were used:
Parameters
ptest
K

1
BPmax
ddefect
1
Table 4 – Parameters for MIT
Description
Specific value
Minimum test pressure
1.59 bars (23.05 psig)
Pore shape correction factor
1.0 (a value of 1 represents
perfect round pore)
Surface tension at the air-liquid-interface at 0.074 N/m
10oC
Liquid-membrane contact angle for
45o
Polyethersulfone-Membranes
Max Backpressure on the system during
0.09 bar (1.3 psi or 36 in)
test.
Size of detectable defect (calculated)
1.4 µm
Based upon third party testing. The water contact angle of a membrane is related to its hydrophobicity;
the more hydrophobic of a membrane, the larger the value of its water contact angle.
Based on the parameters in Table 4, the calculated defect size is 1.4 µm which is well below the
minimum resolution of 3 µm (minimum size of a membrane breach that can be detected). If the
contact angle was assumed to be 0o (most conservative), the calculated defect size would be 2
µm. To ensure the required resolution of 3 µm or less is met, the starting pressure for PDT was
Michael Hank
Seccua Americas
February 8, 2013
Page 6
set at 1.59 bars (23.05 psig) to ensure the ending pressure will achieve a LRV of 4 logs or more
with a resolution of 3 µm or less.
Microbial Contaminant Removal – Cryptosporidium Surrogate
Two membrane modules were challenge tested for Cryptosporidium oocysts based upon the
requirements for challenge testing under the Long Term 2 Enhanced Surface Water Treatment
Rule (LT2ESWTR). In this study, Bacillus subtilis and coliphage MS2 were used as the
challenge particulates. For Cryptosporidium, two challenge runs were conducted using Bacillus
subtilis. Each of the challenge runs lasted approximately 60 minutes. The feed rate for the
challenge organisms ranged from 2.2x104 to 1.2x105 (4.3 to 5.1 log10), well below 3.16x106 (6.5
log10), the maximum allowed under the LT2ESWTR. There were no challenge particulates
detected in the finished water in any of the runs. Overall, the challenge testing met the
requirements of the LT2ESWTR and demonstrated a removal of at least 4.7 log averaged over
the course of each run for Bacillus subtilis.
Microbial Contaminant Removal – Virus Surrogate
For viruses, one challenge run was conducted using MS2. During the one challenge run, no
MS2 was detected in the membrane filtrate. MS2 is a reasonable indicator of enteric virus
removal efficiency, since most enteric viruses are 0.020 to 0.085 µm in diameter while MS2 is
0.03 to 0.04 µm in diameter. The feed rate for the challenge organisms ranged from 2.0x104 to
6.0x104 (4.3 to 4.8 log10), well below 3.16x106 (6.5 log10), the maximum allowed under the
LT2ESWTR. There were no challenge particulates detected in the finished water. Based simply
on the pore size characteristics of the membrane (0.008 µm nominal/0.015 µm absolute), it is
likely that MS2 (0.03-0.04 µm) is removed by size exclusion.
Upper Control Limit
The Upper Control Limit (UCL) signifies the highest allowable pressure decay rate during
a MIT that demonstrates a minimum log removal for Cryptosporidium. An UCL of not
greater than 8.41 mbar/min (0.122 psi/min) will provide greater than 3.0 log reduction of
Cryptosporidium based on most conservative conditions (max TMP = 2.5 bar (36 psi);
minimum flux rate (17.06 L/m2·hr (10 gal/ft2·day) or 4.54 L/min (1.2 gpm) per membrane
unit). The values above are based on the Darcy model for air and water flow through a
cut fiber located at the potting material for shortest path-length. The model was applied
separately for each flow. Water and air temperature used was 20oC. No diffusion losses
were used in the UCL calculations. Below are graphical representations of the variable
flux rates and TMP for an UCL of 8.41 mbar/min (0.122 psi). The graphs are based on
actual calculated air-to-liquid conversion ratio (ALCR) used to calculate LRV. The air
and liquid flows through a ruptured fiber are calculated separately using the Darcy pipe
flow model. Seccua uses a constant ALCR which is conservative over most operating
conditions.
Michael Hank
Seccua Americas
February 8, 2013
Page 7
Michael Hank
Seccua Americas
February 8, 2013
Page 8
Commissioning, Factory & Field Operating Set-Points
The SeccuMem Pro 1000 UF membrane is commissioned to achieve at least 4 log reduction or
greater of Cryptosporidium during operations. A LRV below 4.0 is considered an operational
failure which would require investigation and possible replacement of the membrane module if
warranted. However, immediate replacement of the module may not be necessary or required if
the operating LRV is between 3 and 4 for source waters that are classified as Bin 1 under
LT2ESWTR.
As of the writing of this letter, there are two installations of the Virex Pro 1000 in California. All
MIT failures for the first installed system were the results of leaky valves due to debris such as
PVC shavings left in the clearwell. It was believed that those shavings were pumped from the
clearwell into the membrane system during backwash. Before membrane startup, it is
recommended that all inlet/outlet lines be flushed with clean water to remove debris that could
become lodged in the valves or it may damage the membranes. Other failed MIT were resolved
by opening and closing valves and re-running the MIT test.
Seccua calculates its LRV by using a constant ALCR of 39.61, a constant flow of 3.44 gpm (13
L/min), a constant pressurized system volume (Vsys) of 11.4 liters, a diffusion rate of 0.15
mbar/min (0.00218 psi/min) and the measured pressure decay rate during a MIT. The
membrane unit is rated up to 6.34 gpm (24 L/min). The ALCR value is programed within the
Virex controller and cannot be changed without an engineer’s password. Given that a constant
ALCR is used, the operating TMP is not used as part of the LRV calculations.
The LRV for the SeccuMem Pro 1000 modules can be calculated using one of the following
equations:




193.19Q gpm
3,520Q L/min

 or LRVvirexPro  Log
LRVvirexPro  Log
;
 PDR mbar/min  - d base

 PDR psi/min  - d base

mbar/min  
psi/min  


Where Q is plant flow, PDR is the system pressure decay rate during a MIT and dbase is the
diffusion rate for a new membrane. The constant flow used for the LRV can be based on the
plant’s lowest operating flow since the last MIT. This setting can be changed within the Virex
controller and would require an engineer’s password for access.
The upper control limit (UCL) is the maximum pressure decay rate in a MIT for a targeted LRV.
The UCL is calculated by the following equation:
UCL 
Q flow ALCR Patm
Vsys 10 LRV
Given that the ALCR and Vsys are constant values in the Virex controller, the UCL can be
simplified to the following equations:
 193.19Q gpm
UCL psi/min  
LRV
 10



or
 3520Q L/min 
UCL mBar/min  

LRV
 10

Michael Hank
Seccua Americas
February 8, 2013
Page 9
Graphically shown below are operating system flows versus the upper control limits for a LRV of
4.0 using an ALCR constant of 39.61:
Michael Hank
Seccua Americas
February 8, 2013
Page 10
The system TMP is based on head losses through valves, piping and membrane that are
measured with pressure gages. Graphically shown below are the calculated LRV and ALCR
versus TMP for two lower end flows. As the flow increases, the greater the LRV will be for the
same operating conditions. Because an ALCR of 39.61 is a programmed constant in the Virex
Controller, the graphs below shows a higher LRV for the calculated ALCR and stated operating
parameters. This means that the LRV calculated from the Virex controller will be in general
conservative compared if the calculated ALCR was used for the different operating TMP
parameters.
Although the membrane unit (with two modules) is rated up to 6.34 gpm (24 L/min), Seccua
recommends an operational flow or flux rate that is less than maximum design to minimize
membrane fouling based on source water quality such as turbidity and dissolved organic
carbon.
Seccua modules in factory packaging can be stored up to 24 months as long they are not
exposed to sunlight and stored between 2-30oC.
Prior to commissioning, the configurable parameters should be configured into the software by a
factory authorized representative. Once set, operating parameters relating to MIT and LRV
calculations must not be changed except by a factory authorized representative or with the
consent of the regulatory office.
Michael Hank
Seccua Americas
February 8, 2013
Page 11
Permitting Process
As part of the permitting process for each treatment facility, the parameters used for calculating
the LRV will need to be available for review and verification. The parameters used in the LRV
equations are system specific and dependent on the flux rate, TMP, water and air temperature,
volumetric concentration factor (VCF) and system holdup volume (Vsys). The minimum LRV will
need to be established based on operating TMP, flux rates and MIT results. The Department
will determine the adequacy of the overall treatment plant based on the review of the filtration
and disinfection treatment facilities and the overall integration of the two systems to provide a
reliable multi-barrier treatment system.
Conditional Acceptance
Approval for the design and use of your technology in any drinking water application will be
handled on a case-by-case basis by Drinking Water Program (DWP) district offices or by local
primacy agencies (LPA) and is granted through the domestic water supply permitting process.
Information such as shop drawings and specifications may be requested to aid in the
development of the water supply permit. A commissioning period to assess performance,
integrity and membrane durability on start-up may be required in an effort to ensure that the final
system functions as expected. The DWP district office or LPA is responsible for evaluating the