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The use of ultraviolet light irradiation has emerged as a
viable new technology for the disinfection of large water
supplies, particularly with regard to Cryptosporidium
inactivation. Bioassay tests, which use non-pathogenic
test organisms as surrogates, are typically used to
validate UV reactor performance. The use of bioassay
validations, with high flow rates, become impractical
and uneconomical.The difficulty in handling adequate
quantities of test organisms and the requirements for
large volumes of water under controlled conditions,
presents a major problem. Handling contaminated
water during and after tests presents a number of
issues. Finding a consistent water supply of 20 mgd
adds to these difficulties. How are engineers to scale
up design, provide for performance and specifications,
in a timely and cost effective manner?
CFD/Fluence... The Calgon Carbon Solution
Calgon Carbon process engineers have demonstrated
through the development of UV Design, and
comprehensive use of CFD modeling, that CFD is an
excellent way to validate a UV reactors performance.
Calgon Carbon Corporation has conducted studies
which successfully used CFD to model the results of
validation test runs on full-scale Sentinel™
UV reactors,that were actually tested under the German DVGW
W294 Standard.A very strong correlation became
evident between the dose determined by the
DVGW Test and the dose predicted by the CFD/ fluence
Model. CFD is currently being used to optimize the
existing reactor designs with results showing that gains
in disinfection efficiency of 25-35% can be realized.
Discovery of IV as a Cost Effective Means to Prohibit Cryptosporidium
Contamination In Drinking Water
Patented research conducted in 1997 by Calgon
Carbon Corporation, discovered that doses
for Cryptosporidium inactivation (in-vivo) were
actually much lower than prior work had indicated.
Dose calculations take into consideration various
factors, such as; surface reflection, refraction of the
quartz sleeve surrounding the lamp, lamp effects, and
water and photon characteristics at each wavelength
emitted. Current validation protocol dictates that
these reactor vessels undergo a rigorous series
of challenge tests done largely by third party
organizations.These costs and time delays are often
a hindrance to the expedient implementation of UV
Technology, particularly large-scale reactors. Calgon
Carbon Corporation and the general public realize
the necessity of validation. Calgon Carbon
Corporation currently has two reactors systems
validated with various third party organizations,
such as: DVGW, EPA/NTV, AWWS, and MWD.
Additionally 36 & 48 inch diameter reactors are
scheduled to be validated in 2002.
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