U.S. Environmental Protection Agency
noloov Verification
ET
Ultraviolet (UV) Disinfection Systems for
Secondary Wastewater Effluent and Water Reuse
The U.S. EPA Environmental Technology Verification
(ETV) Program's Water Quality Protection (WQP) Center,
operated by NSF International under a cooperative
agreement with EPA, has verified the performance of three
ultraviolet (UV) disinfection systems1, one for secondary
effluent and two for water reuse applications. These
technologies can be used in place of chemical disinfection to
inactivate or destroy infectious organisms, such as E. coli
and enterrococci, in wastewater treatment plant effluent
prior to release or reuse. Wastewater treatment facilities can
use these technologies to install or upgrade disinfection
systems, thus helping them to comply with discharge
standards, including those under Total Maximum Daily
Load (TMDL) requirements.
Technology
Description
and
Verification
Testing
The ETV-verified
UV technologies
utilize either
"low-pressure" or
"medium-
pressure" mercury
lamps to generate
electromagnetic
radiation that can
penetrate the cell
walls of microbial organisms, eliminating their capacity to
reproduce. All three technologies utilize contact reactors
with lamps mat are enclosed in quartz sleeves. Table 1 lists
the three ETV-verified UV technologies.
(Continued on page 2)
One of the verified UV technologies
Table 1. Verified UV Disinfection Technologies
for Water Effluent and Water Reuse
Technology
Aquionics, Inc.
bersonlnLine®4250UV
System
Ondeo Degremont, Inc.
Aquaray®40HOVLS
Disinfection System
SUNTEC
environmental, Inc.3
LPX200 UV Disinfection
System
Description
Uses high-output, medium-pressure mercury
lamps in quartz sleeves that are oriented
horizontally and perpendicular to the direction of
flow
Uses high-output, low-pressure mercury
discharge lamps in quartz sleeves oriented
vertically and perpendicular to the direction of
flow
Uses high-output, low-pressure UV lamps in
quartz sleeves oriented horizontally and parallel
to the direction of flow
a Company no longer in business
Wastewater Effluent and Water
Reuse Efforts at a Glance
Pathogenic organisms present in wastewater
effluents can cause a variety of diseases in
humans. Pathogen-containing discharges can
limit public use of valuable natural resources
such as beaches, lakes, and rivers. For
example, in 2005, more than 1,100 U.S.
beaches, or 28% of those monitored, were
issued warnings or closed for at least one day
because of water contamination.
To help address the human health effects of
the presence of various pathogens in water,
the EPA sets water quality criteria under the
authority of the Clean Water Act. The EPA
recently established health-based federal
bacteria standards for a number of states and
territories bordering the Great Lakes or
ocean waters. These criteria limit the
geometric mean for enterrococci in marine
coastal recreation waters to 35 colonies per
100 millimeters (35/100 mL), and for fresh
waters, 33/100 mL. For fresh coastal
recreation waters, the criteria limit the
geometric mean of E. coli to 126/100 mL.
Under the Clean Water Act, states are also
required to identify impaired waters that do
not meet water quality standards even after
installation of pollution control technology.
Removal of pathogens is also a primary
concern for a number of states promoting
water reuse projects aimed at conserving
water. EPA and the U.S. Agency for
International Development have jointly
developed a technical document with
guidelines for water reuse. These guidelines
recommend a higher degree of treatment
wherever public exposure to reused water is
expected. UV disinfection is one of the
disinfection processes proposed in the
guidelines. Reuse efforts are necessary in
areas where water scarcity is experienced
because of growing water demands, as well
as in areas subject to drought. In 2005, the
National Drought Mitigation Center
identified 41 states experiencing water-
related drought impacts. Among the
advantages of water reuse are that it
decreases the diversion of water from
sensitive ecosystems, reduces and prevents
pollution, and creates, restores or enhances
wetlands and wildlife habitats.
The ETV Program operates largely as a public-private partnership through competitive cooperative agreements with non-profit research institutes. The
of commercial-ready technologies. Verificati
iiicts or services mentioned in this document.
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 ,-,.-.
-------
(Continued from page 1)
All of the verification tests were conducted at the Parsippany-Troy Hills Wastewater Treatment Plant in
Parsippany, New Jersey. The testing used MS2 bacteriophage as the target organism because of its high
tolerance to UV light. The tests were conducted on water with UV transmittances of 55% and 65%. All of the
verifications measured power consumption and headless results, developed dose delivery-flow curves, and
obtained reactor design data for use in scaling system design for applications larger than those tested. The
technical objective of the tests was to verify the effective delivered dose for each UV system's reactor under
varying flow and water transmittance conditions. Each of the verifications met this objective, developing dose
delivery curves based on the MS2 bacteriophage survival rates observed during testing. Additional information
on the verification of these UV systems can be found at http://www.epa.gov/etv/verifications/vcenter9-5.html
Selected Outcomes of Verified UV Disinfection Technologies
• Based on a 25% penetration of the market for these technologies, the ETV-verified technologies would be
installed at 77 wastewater treatment facilities (out of 309 facilities), and would assist 23 wastewater
treatment facilities (out of 90 facilities) in complying with EPA's new water quality standards for coastal
and Great Lakes recreation waters. The technologies would also enable water reuse at 29 facilities (out of
114 facilities) in Florida and California, resulting in the capacity to recycle at least 140 million gallons per
day of water.
The technologies would replace conventional
chemical disinfection at many of the facilities
mentioned above and, in the process, eliminate
the need to manage hazardous chemicals and
potentially reduce operating costs. Adverse
health effects have been associated with the
conventional method of chemical disinfection
since harmful disinfection by-products, such as
trihalomethanes, may be formed when using
chemical disinfection. Table 2 summarizes the
advantages and disadvantages of UV disinfection
systems over chemical disinfection (such as
chlorination).
Use of the ETV-verified technologies in the
treatment of secondary wastewater effluent
ultimately will reduce exposure of downstream
users to infectious organisms, reducing the
incidence of disease and protecting the public's
ability to use natural resources such as beaches
and rivers.
Table 2. Advantages and Disadvantages of UV Disinfection
Over Chemical Disinfection
Advantages
• Effective at inactivating most
bacteria, viruses, spores, and
cysts
• Eliminates the need to manage
toxic, hazardous, or corrosive
chemicals
• Might not generate harmful
residuals (e.g. trihalomethanes)
• Can be less labor intensive to
operate
• Uses shorter contact times
• Requires less space for
equipment and process
Disadvantages
• Dosage must be sufficient to
deactivate certain organisms
• Organisms sometimes are
able to reverse the
destructive effects
• Preventive maintenance is
more intensive
• Must be designed to account
for turbidity and suspended
solids in wastewater that can
reduce the transmittance of
the UV radiation
• Does not provide a
disinfectant residual, which
may be a disadvantage
where a residual is desirable
Although UV technologies have higher capital costs than chemical disinfection, they generally require a
smaller footprint than chemical disinfection processes. The use of UV disinfection can avoid additional
land costs associated with expanding a treatment facility and can reduce labor cost, as they can be less-labor
intensive to operate.
The ETV verification protocol for validating UV technologies has been acknowledged by the State of
California as meeting the minimum requirement for acceptance of a technology under the State's
regulations for UV disinfection. This provides an advantage for ETV-verified vendors in gaining
acceptance from the State regulatory agency and in marketing their technology in California. Several states
and agencies also have started using the technologies, such as the Flat Creek Water Reclamation Facility in
Gainesville, Georgia, the City of Fairfield, Ohio, and the Laguna County Sanitation District in California.
References
U.S. EPA, ETV Case Studies: Demonstrating Program
Outcomes. Volume II. EPA/600/R-06/082. September
2006. (primary source). http^Avww.epa.gov/etv/pdfs/
publications/600r06082/600r06082.pdf
U.S. EPA ETV, http://www.epa.gov/etv.
Wastewater Technology Fact Sheet Ultraviolet Disinfection.
U.S.EPA Office of Water. 1999. http://wwAV.epa.gov/owm/
mtb/uv.pdf.
ETV Water Quality Protection Center
Ray Frederick, EPA Project Officer
frederick.rav@epa.gov. Tel: (732) 321-6627
Thomas Stevens, NSF International
stevenst@nsf.org. Tel: (734) 769-5347
EPA/600/S-07/015
April 2007
------- |