U.S. Environmental Protection Agency
J LIU
ET
Nanofiltration for Removal of Drinking Water
Disinfection By-Product Precursors
The U.S. EPA Environmental Technology Verification
(ETV) Program's Drinking Water Systems (DWS)
Center, operated by NSF International under a coopera-
tive agreement with EPA, verified the performance of
the PCI Membrane Systems, Inc., Fyne Process Model
ROP 1434 with AFC-30 nanofiltration membranes.1
This nanofiltration system is designed to remove
microbial contaminants in drinking water and reduce
organic content that can act as a precursor in the
formation of disinfection by-products (DBPs). Research
has shown an association between DBPs, which include
total trihalomethane (TTHM) and the sum of five
haloacetic acids(HAA5), and cancer. Studies also show
a possible association between DBPs and other, non-
cancer human health impacts such as increased risk of
adverse reproductive and developmental health effects.
Technology Description and
Verification Testing
The ETV Program conducted verification testing for 57
consecutive days at the Barrow Utilities & Electric
Coop., Inc., in Barrow, Alaska. Barrow is an Inupiat
Eskimo village mat draws raw water year-round from
Isatkoak Reservoir, a surface water source that has
moderate alkalinity, moderate turbidity, and an elevated
organic content. Water quality data were collected on all
source water, permeate, and concentrate streams
produced by the PCI process and analyzed using
Standard Methods for the Examination of Water and
Wastewater, 20th Edition (1998), or EPA-approved
methods. The tested system was equipped with a
membrane module containing 72 tubular polyamide
nanofiltration membranes connected in series. The
system's small footprint, modular construction, and
(Continued on page 2)
DBPs and Their Regulatory
Background at a Glance
DBPs are formed when disinfectants used for
water treatment react with inorganic matter,
such as bromide, and/or natural occurring
organic matter (i.e., decaying vegetation) present
in the source water. Different disinfectants
produce different types or amounts of by-
products. DBPs for which regulations are
established have been identified in drinking
water, including trihalomethanes, haloacetic
acids, bromate, and chlorite.
To help address the potential health effects of
DBPs, EPA has developed rules to control DBP
formation. These rules, the Stage 1 and Stage 2
DBP rules, are part of a set of regulations that
address risks from microbial pathogens and
disinfectants/DBPs. Small drinking water
systems, which EPA defines as those that serve
fewer than 10,000 people each, were required to
comply with the Stage 1 Disinfectants and
Disinfection By-Products Rule (DBPR) by
January 1, 2004. Under the Stage 1 DBPR, EPA
has set standards for TTHM and HAAS in
drinking water of 80 and 60 micrograms per liter
(|ig/L), respectively. EPA also has enacted the
Stage 2 DBPR to further reduce DBPs in
drinking water systems with the highest risk
levels. Drinking water systems serving fewer
than 10,000 people are required to comply with
Stage 2 DBPR TTHM and HAAS monitoring by
October 1, 2013, if no Cryptosporidium
monitoring is required, or October 1, 2014, if
Cryptosporidium monitoring is required. As a
result of the Stage 1 and 2 DBPRs, certain
drinking water systems may use treatment
technologies similar to the ETV-verified PCI
system to control formation of DBPs by
removing the organic precursors. EPA includes
nanofiltration among the best available
technologies (BATs) for compliance with the
Stage 1 and Stage 2 DBPRs.
The PCI nanofiltration technology
ETV Drinking Water Systems Center
Jeff Adams, EPA Project Officer
adams jeff~g),epa.gov. Tel: (513) 569-7835
Bruce Bartley. NSF International
bartlev@nsf.org. Tel: (734) 769-5148
The ETV Program operates largely as a public-private partnership through competitive cooperative agreements with non-profit research institutes. The
program provides objective quality-assured data on the performance of commercial-ready technologies. Verification does not imply product approval or
effectiveness. ETV does not endorse the purchase or sale of any products and services mentioned in this document.
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performance characteristics make it suited to
applications from the smallest drinking water
treatment systems to those that produce up to 50,000
gallons per day. The test skid produced an average of
0.87 gallons per minute of permeate when operated
so that 80% of the raw water supplied to the test skid
was recovered as permeate. The average
transmembrane pressure and specific flux during the
verification study were 88 psig1 and 0.14 gfd/psi,2
respectively. Some of the performance results are
listed in Table 1.
The ETV Program also verified the chemical
cleaning performance of the PCI system. A single
high-pH chemical cleaning cycle at the end of the
two-month continuous verification test recovered at
least 100% of the transmembrane pressure and
specific flux measured at the start of the study.
Performance was approximately the same before at the first day and after cleaning. The ETV tests also
examined operation and maintenance needs, including labor and power requirements. The verification report
can be found at http://www.epa.gov/etv/verifications/vcenter2-7.litml.
Table 1. Average Performance of Selected Parameters of the Verified
PCI Membrane Systems, Inc., Fyne Process Model ROP 1434
Parameter, units
Total organic carbon, (mg/L)
UVWabsorbance
Average TTHM formation poten-
tial in the source water, (|jg/L)
Average HAAS formation poten-
tial in the source water, (|jg/L)
Iron, manganese, calcium, and
sulfate from solution
Initial
Value1
15
0.52
544
405
varies
Final
Value2
0.7
0.012
31
6.7
varies
Reductions,
95%
97%
94%
98%
47-99%
1 Average Feed Water values at 95% confidence interval
2 Average Permeate Water values at 95% confidence interval
mg/L, milligram per Liter |jg/L, microgram per Liter
1pounds per square inch gauge
2gallons per square foot per day per pounds per square inch
Selected Outcomes of the Verified PCI Membrane Systems Nanofiltration Technology
ETV estimates, based on data from the Stage 1 and Stage 2 DBPRs, that approximately 4,800 drinking water
systems will need to install new or modify existing treatment systems to comply with these rules.
Assuming 25% of the market install this device, the ETV Program estimates the following.
• The ETV-verified PCI nanofiltration technology would assist 1,200 small drinking water systems comply
with EPA's DBP standards.
• For these systems, the technology could prevent up to 20 cases of bladder cancer per year.1 The technology
also could prevent other negative human health effects, including developmental and reproductive effects.
• The technology could result in economic benefits of up to $110 million per year due to the prevention of
the above cases of bladder cancer.
Verification has also increased awareness of the ETV-verified nanofiltration technology and its benefits among
state regulatory agencies and potential users. The following benefits have been or can be realized from the avail-
ability and use of the ETV data:
• Twenty-five states reportedly use ETV verification data to reduce the frequency and/or length of site-
specific pilot tests for drinking water treatment and the vendor has reported this result in several installa-
tions of this technology. Drinking water regulations and guidance in several states identify the ETV Pro-
gram as a source of performance verification data and testing protocols.
• Assuming 25% market penetration, 1,200 systems would use ETV data to reduce pilot testing requirements,
saving up to $18 million in pilot testing costs.
• The reduction in pilot testing length also could lead to systems achieving the above health benefits sooner
than would otherwise be possible.
• ETV verification has led to sales of the technology, resulting in reductions in exposure to DBFs with poten-
tial human health and associated economic benefits.
11n 71 FR 388, EPA acknowledges that causality has not yet been established between chlorinated water and bladder cancer and that the actual number
of cases attributable to DBFs could be zero. Therefore, the actual number of cases avoided could be as low as zero.
References
U.S. EPA, 2006. ETV Case Studies: Demonstrating Program Outcomes, Volume II. EPA/600/R-06/001. Sep-
tember. http://www.epa.gov/etv/pdfs/publications/600r06001/600r06001pv.pdf. (primary source)
U.S. EPA, ETV, http://w-ww.epa.gov/etv.
U.S. EPA, Office of Water, 2006. Stage 2 Disinfectants and Disinfection Byproducts Rule: a Quick Reference
Guide for Schedule 4 Systems. June, http://www.epa.gov/safewater/disinfection/stage2/pdfs/
qrg stage 2 dbpr qrg'sch4 final.pdf. EPA/600/S-07/019
June 2007
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