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Until a few years ago,UV disinfection at economical
doses,was considered an ineffective barrier to
Cryptosporidium and Giardia cysts and oocysts.
However,pioneering research launched and funded by
Calgon Carbon Corporation in 1996,led to the
discovery that these organisms could be inactivated and
rendered non-pathogenic,at substantially less dose
levels than ever imagined.This discovery revealed
that broad-band UV light provided better than 99%
inactivation of both Cryptosporidium and Giardia at
UV doses of less than 10mJ/cm2.This discovery contra-
dicted all previous thought on the merits of UV used to
protect drinking waters and led to a Patent on the
process in 1998.
The U.S.Environmental Protection Agency (EPA)and
National Sanitation Foundation (NSF)have verified the
performance of a Sentinel™
Reactor (R-11,Model 6-1)
under the EPA 's Environmental Technology Verification
(ETV)Program.This reactor obtained an estimated 3.9
log inactivation of Cryptosporidium parvum,as deter-
mined by animal infectivity studies,(in-vivo).When these
dose to inactivation correlations are compared to E.Coli
bacteria and rotavirus,protozoa are now revealed to be
among the easiest pathogens to treat using UV light.
Advantages of Sentinel™ UV Disinfection
Surface Water regulations have mandated that
chlorinated disinfection by-products (DBP)not exceed
80ug/L for THAAs.Some water treatment plants may
have difficulty meeting these DBP requirements along
with requirements for Giardia given the large chlorine
dosages need to treat this organism.Plants may need to
increase contact times or try other costly disinfection
technologies such as ozone or membranes.
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