N
o rw
al k
vi
r u s(
N V
)
i
s a nim p
o rt
a nt
c a u s e of
w
at
e rb
o r n eg
a st
r o e nt
e rit i
s,y
et it
s r e sp
o n s et
oU V
d i
si
nf
e ct i
o ni
s u nk
n ow
nN
o n
-c u
lt
u r ab l
e a nd w it h
o ut
a n a nim
al m
od
el
, r e v e r s e-
t
r a n s c ri pt i
o nP C R
(
R T
-P C R
)
o r a n a
lt
e r n at i
v e n u cl
ei
c a cid
am p l if i
c at i
o nm
et h
od i
st h
e o nly p
r a ct i
c al w
ay
t
od
et
e ct
a nd q
u a nt if y t h i
s vi
r u si
nw
at
e r.H
ow
e v e r,
w
eh
a v ef
o u nd t h
at R T
-P C R
u nd
e r e sti m
at
e st h
el
o s s of
vi
r u si
nf
e ct i
vity b y U V
r ad i
at i
o n.I
n a n ef f
o rt
t
oi m p
r o v et h
ep
r ed i
ct
ab i l ity
of R T
-P C R
am p l if i
c at i
o nf
o rt h
el
o s s of
vi
r u si
nf
e ct i
vity b y U V d i
si
nf
e ct i
o n,w
ei
n v e st ig
at
ed
alt
e r n at i
v e st
o si
ng l
e am p l i
c o n,d i
r e ct R T
-P C R
.
I
n ad d it i
o nt
oN V
, c o
li p h
ag
eM S 2
a sw
ell
a sp
ol i
o vi
r u sty p
e3
(
P V 3
)
a nd ty p
e1
(
P V 1
)
w
e r ei
n cl
ud
ed i
nt h
e st
ud y t
o c om p
a r ei
nf
e ct i
vity
a s s a
y
st
oR T
-P C R
a s s ay
sf
o rq
u a nt ify i
ng
vi
r u si
n a ct i
v at i
o nb y U V
r ad i
at i
o n.B
a s ed
o ni
nf
e ct i
vity
a s s ay
s, aU V d
o s e of 1 5 0 m
W
-s e c
/
cm
^ r ed
u c ed M S 2
a n
d P V 1 b y 4
.8
a nd
>5
.8 l
og
i o, r e sp
e ct i
v ely
.B y d i
r e ct R T
-
P C R
am p l ifi
c at i
o no
f g
e n om i
ct
a rg
et
s of
ab
o ut 2 0 0
-2 5 0 B P
,
t h i
sd
o s e of U V
r ad i
at i
o np
r od
u c ed
f
r om
z e r ot
o1 l
og
^t it
e r r ed
u ct i
o ni
n a ny
of t h
et h
r e e vi
r u s e s.I
n o rd
e rt
oi m p
r o v et h
ed
et
e ct i
o n of U V
d
am
ag
et
o vi
r al g
e n om i
cR N A
,R T
-
P C R
a
m p l if i
c at i
o nw
a sp
e rf
o rm
ed
at m
ult i p l
et
a rg
et
s.H
ow
e v e r, e v e n a
t
ah ig h
d
o s e of 5 5 0 m
W
-s e c/
cm
^,
t h
e r ew
a s n oi
n c r e a s ei
nth
e ob
s e r v ed
r ed
u ct i
o ni
n vi
r u st it
e rb y R T
-P C R
am p lif i
c at i
o n of 2 0 0
-2 5 0 B P t
R N A
, a nt ig
e n c ap t
u r e/ R T
-
P C R w
a sa
p p li
ed t
oU V i
r r ad i
at
ed
vir u s e s
.N
os
ig
nif ic a n
t d
e c r e a s ein
A C / R T
-P C R t it
e rw
a s ob
s e r v ed f
o r al l t h
r e e vi
r u s e s ,d
e sp it
e e xt
e n siv e
i
n a ct iv a
t i
o n of th
ein
f
e ct iv
ity
of M S 2
a nd P V 1
A m p l i
c o nl
e ng t h w
a sin c r e a s e
d to
5 0 0
-1 3 0 0 B P i
n a n ef f
o rt t
oi m p
r o v ed
ete c
t io n o
f U V
d
am
ag
e .T h
ei
n c r e a s ein a
m p l i
c o n si
z ebe
tt
e r e st im
ate
d P V 1 i
n a ct i
v at io n
a n
d d
et
e ct
ed
g
r e at
e rin a c
t iv a
t io n a
t
lo
w
e rd
o s e sf
o rN V
.T
h
e r e s ult
s of th is
s
t
ud y i
nd ic a
t
et h
at R T
-P C R
a
m p l if i
c at io n
at m
ult ip l
eg
e n om ic
sit
e s a nd
a n
t ig
e n-c ap t
u r eR T
-P C R
u si
ng
p
oly
clo n a
l
a nti b
od ie s
a r e n ot
r el ia
b le
m
et h
od
st
oq
u a nt if y t h
ein a c
t i
v at io n
of
vi
r u s e sb y U V
r ad i
at io n
.H
ow
e v e r,a
m p lif i
c at io n o
f lo n
g
e rR N A g
e n om ic
t
a rg
et
sm
ay i m p
r o v et h
e ab i lit y
of R T
-P C R t
op
r ed ic
t
r ed
u ct io n o
f
vi
r u si
nf
e ct iv
ity b y U V
r ad i
at io n
.M
a ny t h
a nk
st
oD
r.M
a rk S
ob
s ey f
o rh is s u
p p
o rt
,
in v a
lu a
b l
e e xp
e rt is e a n
d
p
r e cio u s
t i m
e .In a
d d it io n
,
I
am i
nd
eb t
ed t
oD
r.C
a r ol S h ie
h f
o rt h
em
a ny
a
f
te r n o o n s sh
e sp
e nt w it
h m
ein
t h
e c o nf
e r e n c e ro om
a nd
sh
a r ed h
e rc o n s
id
e r ab le
k
n ow l
ed g
e of m
ole c u
la r v
ir o
lo
g y
I
e xp
r e s sm y g
r at it
ud
et
oD
r.F
u
-C h ih H
s u a nd G w y
-A m S h i
n,
tw
of i
n e a nd g
e n e r o u sP h
.D
c a nd i d
ate s
w h
oc o n
t
ri b
ute
d in
m
a ny
v alu a
b le
w
ay
sto
m y M
a st
e r 'U V D i
si
nf
e ct i
o n of N
o rw
ai l
cV i
r u s a nd O t ii e r
E
nt
e ric
V i
r u s e s a nd T h
ei
rD
et
e ct i
o nb y R T
-P C R
B y
S
op h i
eV
.N
ew l
a nd
A d
vis o r :
D
r.M
a rk D
.S
ob
s ey
A t
e cli n
ic a
!
r ep
o rt
s ub m it te
d t
ot h
eF
a c ulty
of t h
eU
niv e r s
ity
of
N
o rt h
C
a r ol in a
at
C h
ap
el
H i l l
in
p
a rt ia
l
f
ulfi l l m
e nt
of
t h
e r eq
uir e
m
e nt
sfo r
t h
ed
eg
r e e of M
a st
e r of
Sc
ie n c e
in
P
ub l i
cH
e alt h
D
ep
a rt me nt
of E
n vir o n
m
e nt
al S
cie n c e s a n
d
E
ng i
n e e rin
g
.L IS T O F F IG U R
E
S A N D T A B L E
S
3
1
.0
I N T R O D U C T IO N
4
2 0
O B J E C T IV E
8
3
.0
L IT E R A T U R E R E V IE
W
9
3 1 D
is in f e c t io n9
3
.2
D
is in f e c t io nK
i n e t ic s1 0
3
.3 F
a c t o r s i nD
r in k in gWa t e r
a n dWa s t e
w
a t e rD
is i n f e c t ion1 1
3
.4
U
l t r a v iol etR
a d ia t io n1 3
3
.5 M
e c h a n ism OFU V IN A
CT IV A T ION1 4
3
.6
F
a c t o r sA
f f ect ingU V T
r e a t m e n t1 6
3
.7
W
a t e r bor n eD
ise ases2 0
3
.8
D
r i n k i n gWa t e r
R
e g u l a t io n2 2
3
.9 E
n t e r icV
i r u s e s2 4
3
.1 0
I
n d ic a t o r s O FW
a t e rQ
u a l it y2 8
3
.1 1 M S 2 B
a c t e r io p h a g e3 0
3 1 2
M
e t h o d s F O RV
i r u sD
e t e c t io n3 1
4 0
M A T E R IA L S A N D M E T H O D S
3 5
4
.1 V
ir u s A N DH
o s tC
e l l s :3 5
4
.1
aN
o rw
alk V ir u s
(
N V
)
3 5
4
.1b
P
ol i
o vir u s
3 5
4
.2 V
i r u sP
r e p a r a t io n3 6
4 3 E
x p e r im e n t a lP
r o c e d u r e3 7
4
.3
aU V D
o si
ng
3 7
4
.3 b
D
o s eM
e a s u r em
e nt
s3 7
4
.4
R
e v e r s e-t r a nsc r ip t io n a n d
E
n z ym at i cA
m p l if ica t io n3 8
4
.4
aS t
i o rt T
a rg
et R T
-
P C R
3 8
4
.4 b
L
o ng T
a rg
et R T
-
P C R
3 9
4
.4
cA
ntib
od y
(
I
m m
u n o affin
i ty)
C
ap t
u r eR T
-
P C R
4 1
4
.5
O
l ig o n ucl e ot id eP
r i m e r s f o rR T
-
P C R
4 2
4
.5
aS h
o rt T
a rg
et P
ri
m
e rP
air s
4 2
4
.5 b L
o ng T
a rg
et P
ri
m
e rP
ai
r s4 3
4
.5
cP
ri
m
e rP
air
S
e n si ti
vi ty
4 3
4
.6 A
n a l y s i s o fV
i r a lA
m p l ic o n s b yA
g a r o s eG
e lE
l e c t r o p h o r e s is4 6
4 7
D
a t aA
n a l y s is4 6
5 0
R E S U L T S
4 8
5
.1 O
v e r v iew
4 8
5
.2
S
h or tT
a r ge tR T
-
P C R D
e t ect i o n o fV
i r u sR
e d uct io n b y
U V
•
A
s s a y4 9
5 4 U V D
is i n f e c t io n b yI
n f e c t iv it yA
s s a y a n dU V V
i r u sR
e d u c t i o n a sD
e t e c t e d B YA
l t e r n a t iv eR T
-P C R A
m p l if ic a t io n
M
e t h o d s5 0
5
.4
aU V
r ed
u cti
o n of
vi
r u sd
et
e ct
ed b y i
nf
e cti
vi ty
a nd R T
-
P C R
o
f
m
ul tip l
e sh
o rt g
e n om
i
ct
a rg
et
s :5 0
5
.4 b
U V
r ed
u cti
o n of
vir u s
d
ete c
te
d b y i
nf
e cti
vi ty
a nd A C / R T
-
P C R
of
m
ult ip l
e sh
o rt g
e n om
i
ct
a rg
ets :
5 1
5
.4
cU V
r ed
u cti
o n of
vi
r u sd
et
e ct
ed b y i
nfe c
ti
vi ty
a nd R T
-
P C R
o
f lo n
g
g
e n om
ic
t
a rg
ets :
5 2
5
.4 d C
om
p
a ris o n
of U V
r ed
u cti
o nb y
al t
e r n ati
v eR T
-
P C R
m
e
th
od
s :.5 3
5
.5 U V D
is in f ec t io n o fN V
,P
o l io v i r u s a n dM S 2
a n dT
h e i rD
e t e c t io nB Y
A
l t e r n a t iv eR T
-P C R A
m p l if i c a t io nM
e t h o d s a n dI
n f e c t iv it y5 5
6
.0
D IS C U S S IO N
6 5
7
.0 C O N C L U S IO N S
7 0
F ig
u r e5
.1
:U V R
ed
u cti
o n of N V
,P V 1
, a nd M S 2 B
a s ed
o nI
nf
e ct i
vity
A
s s ay
a nd R T
-P
C
R A m p l if i
c at i
o nM
eth
od
sF
ig
u r e5
.2
:U V
R
ed
u cti
o n of P
ol i
o vi
r u sB
a s ed
o nI
nf
e ct i
vity A
s s ay
A lt
e r n at i
v eR T
-P C R A
s s ay
sF ig
u r e5
.3
:U V R
ed
u ct i
o n of M S 2 B
a s ed
o nI
nf
e ct i
vit y A
s s ay
a nd
A lt
e r n at i
v eR T
-P C R A
s s ay
sF ig
u r e5
.3
:U V R
ed
u ct i
o n of N V B
a s ed
o nI
nf
e ct i
vity A
s s ay
a nd
A lt
e r n at i
v eR T
-P C R A
s s ay
sT
ab l
e5
.1
:R
ed
u ct i
o n of N
o rw
alk V i
r u s,P
ol i
o vi
r u s a nd M S 2 b y
U
V
R
ad i
at i
o nb
y
I
nf
e ct i
vity
A
s s ay
a nd S h
o rt T
a rg
et R T
-P C R
T
ab l
e5
.2
:R
ed
u ct i
o n of
N
o n w al k V i
r u sb y
U
V
R
ad i
at i
o n at M
ult ip l
eT
a rg
et
sb y D i
r e ct
a nd A
nt ib
od y C
ap t
u r eR T
-P C R
T
ab l
e5
.3
:R
ed
u ct i
o n of N
o n w al k V i
r u s,P
ol i
o vi
r u s a nd M S 2 b y U V
R
ad i
at i
o nL
o ng T
a rg
et
a nd S h
o rt T
a rg
et R T
-P C R
a n
d I
nf
e ct i
vity A
s s ay
T
ab l
e5
.4
:R
ed
u ct i
o n of M S 2 b
y
U V
R
ad i
at i
o nD / R T
-P C R
a n
d A C / R T
-P C R
A m p l if i
c at i
o n of
S
h
o rt T
a rg
et
sT
ab l
e5
.5
:R
ed
u ct i
o n of N
o rw alk
V i
r u s,P
ol
i
o vi
r u s a nd
M
S
2
b
y A C / R T
M
a n ag
em
e nt
of d
rin
k in
g
w
at
e rm ic r o
b ia
l q
u al ity
a nd
d is
i
nf
e ct io n
e
f f ic a c
y i
s c u r r e nt ly d
ep
e nd
e nt
o nth
em
e a s u r em
e nt
of
c o n c e nt
r at i
o n s o rf
r eq
u e n cy
of
o c c u r r e n c e of i
nd ic a
to r o r
g
a nis
m
s ,p
ri m
a rily
e nt
e ric
b
a ct
e ria
,a s a s u r r o
g
at
ep
a r am
et
e r of f
e c al
c o nt
am in a
t io n
.H
um
a n e nt
e ric
vi
r u s e sa r e a s
ig
nif ic a n
t
c a u s e of w
at
e rb
o r n ed is e a s e
;h
ow
e v e r,th
ey
a r e r a r ely
m
e a s u r ed i
nw
ate r
b
e c a u s et h
ei
rd
et
e ct io n
b y
c o n v e nt io n a
l
c ell
c ult
u r ea s s a
y i
sl im it
ed b y it
ste c
h
nic a
l d if f ic u
lty
, c o st
a nd l
ow
s e n sit iv
ity
.E
nt
e ri
cv
ir u s e s
g
e n e r al ly h
a v e ag
r e at
e r r e sis
ta n c e
t
o c o n v e nt io n a
l
ch lo r
in e
d is
in
f
e ct io n
a nd
a r ef
r eq
u e nt ly d
et
e cte
d i
nf in
is
h
ed
w
ate r
m
e et in
g t h
ec u r r e n
t
c ol if
o rm b
a ct
e ria s
t
a nd
a rd
s.A lth
o ug h
c o n v e nt io n a
l
vir u s
d
et
e ct io n
m
et h
od
s a r et im
e c o n s um in
g
, e xp
e n siv e
, a nd
slo
w t
op
r od
u c e r e s ults
,t h
er e c e n
t
In
f
o rm
at io n
C
ol le c
t io n
R
eg
ula
t io n
(
IC R
)
r eq
uir e s
t h
at
t h
e s em
et h
od
sb
e uti l iz e
d in
th
em
o nito r
in
g
of
s u rf
a c e s o u r c e s of d
rin
k
in
g w
at
e ro n a n
in
t
e ri m ba sis
R
e c e nt
ad
v a n c e sin
m
ole c u
la r
t
e ch
niq
u e s c ap
ab le
of
r a
p id
a nd
s e n sit iv e
d
ete c
t io n
of
vir a
l
n u cle
ic
a ci d
sm
ay
p
r o vi d
e a ni m p
r o v ed m
et h
od t
om
o nit
o rim p
o rt
a nt
vi
r al p
at h
og
e n sin
w
at
e r.R
e sp
o n si b le
f
o r up t
o2 3
%
of w
at
e rb
o r n e a c ut
eg
a st
r o e nt
e rit i
si
nt h
eU
.S
.(
K
ap l
a n,1 9 8 2
)
,N
o n w al k
vi
r u s(
N V
)
a nd
r ela
t
ed
vi
r u s e sm
u st b
ea
d d
r e s s ed i
nt h
em
a n ag
em
e nt
of d
rin
k i
ng w
at
e rq
u alit y
.H
ow
e v e r,t h
ela c
k
of
s uit
ab l
ela
b
o r at
o ry t
e ch
niq
u e sh
a sli m it
ed t h
e ab i lit y t
od
et
e ct N V i
ns e n s
it iv e
m
et h
od t
od
et
e ct N V
a nd
ot h
e r e nt
e ric
vir u s e s
.H
ow
e v e r, a
s
ig
nif ic a n
t l im it
at i
o n of R T
-P C R is
it
sin a
b i l ity t
od
ete c
t in
f
e ct io u s
vir u s
p
a rt i
cle s
.T h
e r ela
ti
o n sh ip b
etw
e e nR T
-
P C R
am p lif i
c at io n
of
vir a
l
n u cle
i
ca c
id
a nd t h
ep
r e s e n c e of i
nfe c
t io u s
vir a
l p
at h
og
e n sh
a sb
e e np
o o rly
c
h
a r a cte r
iz e
d
U V
r ad ia
t io n
is
ap
r om is
i
ng
d is
i
nf
e ct io n
t
e ch
n olo
g
y f
o rd
rin
k i
ng
w
at
e r a nd
ot h
e rw
at
e r s, e sp
e cia
l ly
w it h
in c r e a s e
d
c o n c e r n ab
o ut
c
h lo r
in a
t io n
b y
-p
r od
u ct
s.U V
r ad i
at io n
ap p
e a r sto
ef f
e ct iv e
ly i
n a ct iv a
t
e av a r
ie
t y
of m i
c r o o rg
a nis
m
sw it h
o ut g
e n e r at in
g t
o xi
c r e si d
u als
a nd
sh
ow
sp
r om i
s e a s ad i
sin
f
e ct io n
alt
e r n at i
v et
o ch l
o ri
n e .T h
em i
c r ob i
al
ef f
e ct
of
U V
at 2 5 4
nm is
b
elie v e
d t
ob
ed
u eto
d
am
ag
e of t h
em ic r o
b ia
l g
e n om
eb y
t h
ef
o rm
at io n
of p y
rim id i
n ed i m
e r s,h y d
r at
e s a nd
ad d
u ct
sW
h ile
U V
d
am
ag
et
om
o st
vir u s e s
,p
a rt ic u
la r
l
y
sin
g
le
-s
t
r a nd
ed
vir u s e s
s u ch
a sN
o rw
al k
vi
r u s,i
sir r e v e r s
i b l
e , a ni m p
o rta n
t q
u e st i
o ni
sw h
et h
e rd
am
ag
et
ot h
e n u cle
ic
a cid
, a nd
c o n s eq
u e nt ly t h
elo s s
of
vi
r al in
f
e ct iv
it y
, c a nb
ec o r r e
la
t
ed t
o a r ed
u c ed R T
-P C R
am p l if
ic at io n s
i g
n al.
T h
ep
u rp
o s e of t h is
st
ud
y i
st
od
et
e rm in et h
eU V
i
n a ct iv a
t io n
of
N
o rw
al k
vi
r u s a nd
,f
o r c om p
a ris o n
,p
olio v
ir u s
a nd M S 2
, am
ale
- sp
e cif i
cR N A
c ol i p h
ag
e .V i
r u s r ed
u ct i
o n, a sd
et
e rm i
n ed b y R T
-P C R
e n
d p
oi
nt
t it
r at io n
w
a s c om p
a r ed
t
o vir u s
r ed
u ct i
o nb y
c el l
in
f
e ct iv
ity
a s s ay
.H
ow
e v e r,R T
-
P C R m
ay d
et
e ct t h
e n u cle
i
c a cid
of
n o n-in
f
e ct io u s a s
w
el l
a sT h
e s e alte r n a
t iv e
ap p
r o a ch
e sin c
l
ud
ed
a nt ib
od y
c ap t
u r eR T
-P C R
(
A C / R T
-P C R
)
a nd
d i
r e ct
R T
-P C R
(
D / R T
-P C R
)
am p l if i
c at i
o n of
m
ult i p l
e sh
o rt
T h
e ob
j
e cti
v e of t h i
si
n v e st ig
at i
o nw
a st h
ed
e v el
op m
e nt
of
a ni m p
r o v ed
R T
-P C R m
et h
od w h i
ch w
o ul d
e n ab l
et h
ed
et
e ct i
o n of U V i
n a cti
v at
ed
vi
r u s ,p
a rt i
c ul
a rly
vi
r u s s u ch
a sN
o rw
al k
vi
r u sw h i
ch
a r e c u r r e nt ly w it h
o ut
3
.0
L IT E R A T U R E R E V IE
W
3
.1
D i
si
nf
e ct i
o nA p p li
c at io n o
f d is
in
f
e ct io n
p
r o c e s s e sis
a nim p
o rt
a nt b
a rri
e r ag
ai
n st
p
at h
og
e ni
cm ic r o o r
g
a nis
m
sin
t h
ep
r od
u ct i
o n of f in
is
h
ed w
a te rf
o rp
ub l i
cc o n s u
m p t i
o n a nd t h
et
r e atm
e nt
of w
a st
ew
at
e r eff l
u e nt f
o r r ele a s e
t
ot h
ee n v
ir o n
m
e nt
.I
n1 9 0 8
,
t h
ef ir s
t
c o nt i
n u o u s ap p l i
c at io n
of
ch lo
ri
n ew
a su
t i liz e
d t
ot
r e at
am
u nic
ip
al w
at
e r s up p l y
(
C
r a u n ,1 9 8 6
;D y
ch d
ala
,1 9 8 3
)
.T h
e r o ut i
n e u s e of
ch lo r
in e
d i
si
nf
e ct io n
a nd
th
ein
t
r od
u ct i
o n of w
at
e rf ilt
r at io n
h
a v ed
r a st i
c ally
r ed
u c ed t h
e n um b
e r of
ep i d
em ic s
c a u s ed b y
w
at
e rb
o r n ei
nf
e ct i
o u sd i
s e a s e s(
C
r a u n,1 9 8 8
)
.D is
in
f
e ct io n
is
ut i liz e
d
b
ot h
b y d ri
nk i
ng
w
at
e r a nd
w
a ste
w
at
e rt
r e at m
e nt
p l
a nt
st
op
r od
u c ef i
nis
h
ed
w
at
e r a nd
ef fl
u e nt
of
sp
e cif i
cm ic r o
b i
al q
u al ity
.I
nd ri
nk i
ng w
at
e r,
p ri m
a ry
d is
in
f
e ct io n
a ch ie
ve st h
ed
e sir e
d p
at h
og
e nk i l l,
w i th t h
e s e c o nd
a ry
d is
i
nfe c
ti
o np
r o vi d in
g
a st
ab l
er e s
id
u al in
t h
ef in
is
h
ed w
at
e rt
op
r e v e nt
r eg
r ow t h
of m ic r o
b ia
l p
at h
og
e n sin
t h
ed is
t
rib
ut io n s
y
st
em
.In
th
e c a s e of w
a st
ew
at
e r,
d i
sin
f
e ct io n
is
t h
em
o st
i m p
ort
;a nt
st
ag
ein
t h
ep
r o c e s sin
g
of p
at h
og
e n-c o nta
in
in
g w
a st
ew
ate r s u c
h
t h
at it i
s s uit
ab le
f
o r r ele a s e
to
s u rf
a c ew
ate r s
o r, a sw
ate rb
e c om
e s a ni
n c r e a sin
g ly l im it
ed
r e s o u r c e,w
a st
ew
at
e r r e u s e.A
s a str o ng
o xi d
a nt
, ch lo
ri
n ei
s a n eff
e ct iv e
b
a ct
eri
ci d
e a nd
r e
m
o v e s u nw
a nted
c olo r
, r ed
u c ed i
r o n a nd m
a ng
a nes e .C h lo
ri
neis
als o
seco nda ry d isinfecta nt. Ho
w
eve r, in 1 9 7 4 Ro ok i de nt ified
ch lo
rof
o rm
a s ab y
-p
r od
u ct
of
ch l
o rin e
d i
sin
f
e ct io n
.E
vi d
e n c e of p
o s si b l
e ad
v e r s eh
e alt h
e
f f
e ct
s of t
ri h
al
om
et h
a n e s(
T H M
s)
a nd
ot h
e rd is
in
f
e ct i
o nb y
-p
r od
u ct
s(
D B P
s)
a sw
el l
a sg
r ow in
g
c o n c e r n ab
o ut t h
e e n vir o n
m
e nt
al im p
a ct
of
to x
ic
r e sid
u als
in
t
r e at m
e nt p l
a nt
ef fl
u e nts
(
W
a rd
a nd D
eG
r a e v e ,1 9 7 8
)
,m
oti
v at
e s r e s e a r ch i
nto
t h
e eff ic a c
y
a nd i m p
a ct
of
alt
e r n at iv e
d is
in
fe c
ta n
t
s,in c
l
ud in
g
ult
r a vio
le
t
r ad ia
ti
o n.3
.2 D is
in
f
e ct io n
K i
n et i
c sIn
1 9 0 8
,H
a rie
t t
eC
h ic
k d
e s c ri b
ed
e xp
o n e nt ia
l d is
i
nfe c
t io n
k i
n eti
c sb
a s ed
o nt h
e c o r r ela
t io n
b
etw
e e nt h
e r at
e of i
n a ct iv a
t io n o
f
a nt h
r a x sp
o r e sb y
ch lo r
i
n e a nd
k
n ow
n ch
em ic a
l
r e a ct io n
k i
n eti
c s.I
nt h is
eq
u at io n
, n ow
k
n ow
n a sC h ic
k
'sla
w
(
C h i
ck
,1 9 0 8
)
,th
e n um b
e r of
o rg
a nis
m
sd
e st
r oy
ed
p
e r u ni t t i m
eis
p
r op
o rt io n a
l t
ot h
e n um b
e r of
o rg
a nis
m
s r em
ai
nin
g
:d N / d t
= -k N
I
nt h is e
q
u at io n
,N
i
st h
e n um b
e r of
s u r vi
v o r s ,d
N
/d t i
st h
e r at
e of k i ll
, a nd k
Is
a c o n st
a nt
, v a ry i
ng w it h t h
e ch
a r a cte r
is
ti
c s a nd
c o n c e nt
r at i
o n of t h
ed is
in
fe c
t
a nt
.In
t
eg
r at io n
of t h is
eq
u at io n
p
r od
u c e st h
e e xp
o n e nt i
al k i ll
c u r v e :
N
/
N
o = e ""o r
ln
N / N
o= -k t
T h is
eq
u at io n
d
e s c ri b
e s af ir s
t
-o rd
e r "si
ng l
e -h it
" r e a ct i
o nth
at
a s s um
e st h
ec o n c e n
t
r at io n
of d is
in
f
e ct
a nt i
s e s s e nt ia
l ly
c o n st
a nt w it h t im
e .T h
e r at
et
em p
e r at
u r e ,p H
a nd
ch
a r a cte ri
sti
c s of
th
e ta rg
et org
a nism
C h i
ck
's
e
q
u at i
o n a s s um
e s ah
om
og
e n e o u sp
at h
og
e np
op
ul
at i
o n.I
nt h
e s am
ey
e a r,W
at
s o n e xt
e nd
ed t h i
s eq
u at i
o nt
od
e s c rib
et h
er e
l
at i
o n sh ip b
etw
e e nd i
si
nf
e ct
a nt
c o n c e nt
r at i
o n a nd t h
e r eq
ui
r ed
c o nt
a ct
t im
et
op
r od
u c e a c e rt
ai
ni
n a ct i
v at i
o n.T h i
s eq
u at i
o ni
s n ow k
n ow
n a st h
eC
h i
ck
-W
a
t
s o nm
od
el
:d N / d t
= -k C
"N
I
nth i
s eq
u at i
o n,N
i
sth
em i
c r ob i
al
c o n c e nt
r at i
o n ,C
i
st h
ed i
si
nf
e ct
a nt
r e s
i
d
u al
,t i
st h
et i m
e ,k
a nd
n a r ek i
n et i
cp
a r am
et
e r s.I
nt h i
s eq
u at i
o n(
W
at
s o n ,1 9 0 8
)
,W
at
s o nd
e s c ri b
e st h
eC
t
c o n c ep t
, af
u nd
am
e nt
al t
o ol i
nt h
ed i
si
nf
e ct i
o n r eg
ul
at i
o n s c u r r e nt ly
s et b y E P A
.C
u r r e nt
st
a nd
a rd
s a r es e
t b y t h
eE P A i
nth
eS
u rf
a c eWa
t
e rT
r e at m
e nt R
ul
e(
S
W
T R
)
G
uid
a n c eM
a n u al
a nd
a r et
ab
ul
at
ed
b y d i
si
nf
e ct
a nt ty p
e ,p H
a nd
t
em p
e r at
u r e .W
at
e rt
r e at m
e nt
ut i lit i
e sm
u st
m
e et
p
at h
og
e n r em
o v al
-i
n a ct i
v at i
o nr e
g
ul
at i
o n sb y
s at i
sfy i
ng t h
e ap p
r op
ri
at
eC t
c o nd
it i
o n s.3
.3
F
a cto
r si
nD
ri
nk i
ng
Wa
t
e r a nd
Wa s
t
ew
at
e rD i
si
nf
e ct i
o nW
at
e rt
r e at m
e nt
p l
a nt
s ut i l i
z eb
ot h
p
ri m
a ry
a nd
s e c o nd
a ry
d i
si
nf
e ct
a nt
si
nt h
ep
r od
u ct i
o n of f i
ni
sh
ed w
at
e r.P
ri m
a ry
d i
si
nf
e ct i
o na c
h i
e v e st h
et
a rg
et l
e v el
of m i
c r ob
i
al i
n a ct i
v at i
o n o rk il l
.I
nt h
e c a s e of
d
ri
nk i
ng w
at
e r, a s e c o nd
a ry
ch
em i
c al d i
si
nf
e ct
a nt i
s ap p l i
ed t
om
ai
nt
ai
n ar e s
id
u al
c o n c e nt
r at i
o ni
nf i
ni
sh
ed w
at
e rt
op
r e v e nt
r eg
r ow t h
of p
at h
og
e ni
c-t
r eat m
e nt
c o nt
am
in at ion fr om
ot he r so u rce s Fa cto r s s u ci
i a sp
ath
oge no c c u r r e n c e, s
i
z e a nd
ot h
e r c o n st it
ut i
v e ch
a r a ct
e ri
st i
c s, r e si
st
a n c et
od i
si
nf
e ct
a nt
,h
o st
sp
e ci
f
i
cit y
,i
nf
e ct i
o u sd
o s e, a nd w
at
e r o rw
a st
ew
at
e rq
u al it y m
u st
b
e c o n sid
e r ed
i
nt h
e s el
e ct i
o n a nd
ap p l i
c at i
o n of
t h
ed i
si
nf
e cti
o nm
et h
od
.T h
ed i
v e r sit y
of
vi
r al
,b
a ct
e ri
al
a nd
p
r ot
o z o a np
at h
og
e n st h
at m
u st
b
e c o nt
r ol l
ed b y d
ri
nk i
ng w
at
e r a nd w
a st
ew
at
e rd i
si
nf
e ct i
o n c om p l i
c at
e sd i
si
nf
e ct i
o np
r a ct i
c eE
nt
e ri
c vi
r u s e si
np
a rt i
c ul
a r sh
ow l
a rg
e v a ri
ab i li ty i
nt h
ei
r s e n sit i
vit i
e st
od i
si
nf
e ct
a nt
s.L i
u et
al
.(
1 9 9 5
)
i
n v e st ig
at
ed
t h
et im
en e e
d
ed f
o r4 l
og i
n a ct i
v at i
o nw it
h 0
.5 m g / l f
r e e ch l
o ri
n e .T h
e r ew
a s o v e r al
og
io v a ri
at i
o n, r a ng i
ng f
r om
3 6
.5 m i
n ut
e sf
o rp
oli
o vi
r u s,
ty p
e2 t
o2
.7
m i
n ut
e sf
o r r e o vi
r u s1
.S i m il
a r v a ri
at i
o n si
nd i
si
nf
e ct
a nt
s e n sit i
vit i
e s a r es e e n
i
nb
a ct
e ri
a(
B
utt
e rf i
eld
,19 4 8
)
a nd p
r ot
o z o a n(
C h
a ng
,1 9 4 4
)
.W
at
e r s o u r c e s v a ry
i
nt h
ep
at h
og
e n st h
ey
c o nt
ai
n a nd
c o n s e
q
u e nt ly d i ff
e ri
nt h
ei
rt
r e at m
e nt
r eq
ui
r em
e nt
s.A
c c o rd i
ng t
ot h
eS
af
eD
ri
nk i
ng
W
at
e rA
ct
,w
at
e r ut il it i
e s s e r vi
ng g
r e at
e rt h
a n2 5
c u st
om
e r sm
ay
s o o n
b
e r eq
ui
r ed t
od i
si
nf
e ct g
r o u nd w
at
e r,w h il
e s u rf
a c ew
at
e r s o u r c e sm
u st b
ep
r o c e s s ed
b
ot h
b y d i
si
nf
e ct i
o n a nd
fi lt
r at i
o n.C
o nt
am i
n at
ed
g
r o u nd w
at
e rh
a sb
e e n c o n si
st
e nt ly
r e sp
o n si b l
ef
o rm
o r ew
at
e rb
o r n eo u
tb
r e ak
st h
a n c o nt
am i
n at
ed
s u rf
a c ew
at
e r(
C
r a u n,1 9 9 0
)
.I
nt h
ep
e ri
od
b
et w
e e n1 9 7 1
-8 5
, c o n
t
am i
n at
ed
, u nt
r e at
ed
a nd i
n ad
eq
u at
ely d i
si
nf
e ct
ed
g
r o u nd
w
at
e rw
a s r e sp
o n sib l
ef
o r4 9
%
of th
ew
at
e rb
o r n e o ut b
r e ak
s .r e s
p
o n si b l
ef
o r2 4
%
of w
at
e rb
o r n e o ut b
r e ak
s(
C
r a u n ,1 9 9 0
)
.T
u rb i d ity
,
p H
,t
em p
e r at
u r e,m
ai
nt
e n a n c e of
d i
si
nf
e ct
a nt
r e si d
u al
,d i
si
nf
e ct
a nt
c o n c e n
t
r ati
o n a nd
c o nt
a ct
tim
e a r ei m p
o rt
a nt p
a r am
et
e r sw h i
ch m
u st b
em
o nit
o r ed b y t
r e at m
e nt p l
a nt
op
e r at
o r st
o a ch i
e v e ad
eq
u at
ed i
si
nf
e ct i
o n of
w
at
e r a nd w
a st
ew
at
e r.3
.4
U l t
r a vi
ol
et R
ad i
at i
o nS
u nl ig h t h
a sb
e e n ut il i
z ed f
o r c e nt
u ri
e s a s at
r ad it i
o n al f
o rm
of
d
ri
nk i
ng w
at
e rd i
si
nf
e ct i
o n.I
nt h
e e a rly 1 9 0 0
'
s ,
U
V
r ad i
at i
o nw
a s u s ed t
ot
r e at
m
u ni
cip
al w
at
e r s up p l i
e s(
O
l i
v e r a nd C
a r ey
,1 9 7
6
)
.H
ow
e v e r,d
u et
oe c o n o
m i
c a nd
t
e ch
n ol
og i
c al
ad
v a nt
ag
e s , ch l
o ri
n at i
o nb
e c am
et h
ed i
si
nf
e ct i
o nm
et h
od
of
ch
oi
c eW
it h i
n c r e a s ed
c o n c e r n ab
o ut
ch l
o ri
n eg
e n e r at
ed d i
si
nf
e ct i
o nb y
-p
r od
u ct
s a nd
n ew U V t
e ch
n ol
og y
,i
n cl
ud i
ng t h
ep
r od
u ct i
o n of
n ew
,h ig h
e ri
nt
e n sit y
,m
ed i
um
p
r e s s u r eU
V
l
am p
s ,U V
d i
si
nf
e ct i
o ni
sg
ai
ni
ng
s up p
o rt
a s a n e c o n om i
c a nd
ef f i
ci
e nt
alt
e r n at i
v ed i
si
nf
e ct i
o nm
et h
od
(
S
ch
eib l
e a nd B
a s si
el
,1 9 8 1
;Q
u ail
s et
al
.1 9 8 9
)
.U V
r ad i
at i
o ni
sh ig h ly
ef f
e ct i
v ef
o ri
n a ct i
v at i
o n of
vi
r u s e s a nd
b
a ct
e ri
a a nd h
a s s e v e r al
ad
v a nt
ag
e s o v e r ch l
o ri
n e a nd
ot h
e r ch
em i
c al
d i
si
nf
e ct
a nt
s.U
V d i
si
nf
e ct i
o n u nit
s a r e r e ad i ly
a v ail
ab l
e,
p
r od
u c e n ot
o xi
cr e s
id
u al
, a r e r el
ati
v ely
si m p l
et
o op
e r at
e a nd m
ai
nt
ai
n , r eq
ui
r eli tt l
e sp
a c ea n
d
r eq
ui
r e sh
o rt
c o nt
a ct t im
e s r el
at i
v et
o ch
em i
c al d i
si
nf
e ct
a nt
s(
V
e n o s a,1 9 8 3
)
.T h
e s e ch
a r a ct
e ri
sti
c sm
ak
eU V
a n att
r a ct i
v e ch
oi
c ef
o rg
r o u nd
w
at
e r s o u r c e s of d
ri
nk i
ng
w
at
e r a sw
ell
a sw
a st
ew
at
e rt
r e at m
e nt
C
urr e ntly
,6 0
0m
u ni
cip
alw
a stew
ate r tr e atm
e ntp l
a nts uti l i
z eU V
a s ad i
si
nf
e ct
a nt p
r o c e s s(
B l
at
ch l
ey
,1 9 9 6
)
T y p i
c ally
,U V
r ad i
at i
o ni
s u s ed i
ns
m
all
e rt
r e at m
e nt f
a ci l it i
e sd
u et
ot h
e c om p l
e xit i
e s of l
a rg
e r sy
st
em
st h
at
r e
q
ui
r et h
o u s a nd
s of l
am p
s .T h i
sm
ay
ch
a ng
e a s n ew
,h ig h
e ri
nt
e n sity U V
l
am p
sb
e c om
e a v ai l
ab l
e .T h
e s e n ew
,
m
ed i
um
-p
r e s s u r e ult
r a vi
ol
et l
am p
sp
r od
u c e ah i g h
e ri
nt
e n sity
of U V
r ad i
at i
o n a c r o s s ab
r o ad
e r sp
e ct
r um
.T h i
s c ap
a city
p
r od
u c e s ab
ett
e rU V
d i
si
nf
e ct i
o n c ap
a city
p
e rl
am p
,i
n c r e a s e st h
e c o st
- ef fi
ci
e n cy
of U V d i
si
nf
e ct i
o n a nd m
ay p
r o vid
e ef f
e ct i
v eU V i
n a ct i
v at i
o n of p
r ot
o z o a n cy
st
s.3
.5
M
e ch
a ni
sm
of U V I
n a ct i
v at i
o nU V d i
si
nf
e ct i
o ni
n v ol
v e s a r ad i
at i
o n e n e rg y
,t
r a n sm itt i
ng
e n e rg y t
oa
t
om
s o rm
ole c u
l
e sby
e x cit
at i
o n r at h
e rt h
a ni
o ni
z at i
o n.A
s op p
o s ed
t
oc o r
p
u s c ul
a r r ad i
at i
o n, el
e ct
r om
ag
n et i
cw
a v e r ad i
at i
o nt
r a v el
s at
a c o n st
a nt
v e
l
o cit y
, v a ry i
ng
w
a v el
e ng t h
a nd
f
r eq
u e n cy
i
n v e r s ely t
op
r od
u c et h
ec o n s
t
a nt
v el
o city
of
1 8 6
,0 0 0
m i l
e sp
e r s e c o nd
.A lt h
o ug h
, u
lt
r a vi
ol
et
r a
d i
at i
o nt
r a v el
s a s a n el
e ct
r om
ag
n et i
cw
a v e ,it b
eh
a v e s a sif
ad i
s c r et
eq
u a nt
a of
e n e rg y
.T h
em
a rk
ed
p h
ot
o ch
em i
c al
a nd
p h
ot
ob i
ol
og i
c al
p
r op
e rt i
e s of
ult
r a vi
ol
et
r ad i
at i
o n a r e a c o n s eq
u e n c e of it
s r el
at i
v ely
sh
o rt
w
a v el
e ng th
,h ig h f
r eq
u e n cy
a nd
, c o n s eq
u e nt ly
, th
el
a rg
e-e n -e r
g y
of U V
q
u a nt
a .D i
s c o v e r ed i
n1 8 0 1 b y J
.W
.R itt
e r,
U V
r ad i
at i
o nw
a sf i
r st
ob
s e r v ed
a s a
d
a rk
r eg i
o nb
ey
o nd t h
e vi
si b l
es u c
h
a st h
o s eb y G
at
e s(
19 2 9
)
a nd S y
ke s
(
1 9
6 5
)
s ep
a r at
ed
ul
t
r a vio
le
t
r a
d i
at i
o ni
nt
od if f
e r e nt w
a v el
e ng t h
s of m
o n o ch
r om
at i
cl ig h t
a nd i d
e nt if i
ed
t h
eU V
sp
e ct
r um
of p
ri m
a ry b
a ct
e ri
cid
al i m p
o rt
a n c e a sf
r om 2 4 0 t
o2 8 0
n
m
.T
h
eU
V
a ct
io n
sp
e ct
r a s ug
g
e st
st h
at t h
ep
ri m
a ry
g
e rm
ic
id
al
ef f
e ct
of
U V
r ad i
at i
o ni
s c a u s ed b y
n u cl
ei
c a ci d d
am
ag
e(
L
eh m
a n a nd O l
s o n,1
9
8 3
;V
e n o s a,1 9 8 3
;R
og
e r s ,1 9 8 5
)
.U V i
n a ct i
v at i
o ni
sp
r op
o rt i
o n al t
ot h
eU V d
o s e a nd h
a sb
e e n sh
ow
nt
of
ol l
ow
C h i
ck
'
s
L
aw
(
L
u ck i
e sh
a nd H
ol l
ad
ay
,1 9 4 4
)
p
o s sib l y t h
r o ug h
f
o rm
at i
o n of
p y
rim i d i
n ed im
e r s , a nd
t
o al
e s s e r e xt
e nt
,p y
ri m id i
n eh y d
r at
e s,p y
rim id i
n e-
t h y m i
n e ad d
u ct
s a nd U V
i
nd
u ct i
o n of
si
ng l
e-st
r a nd
b
r e ak
s(W
i tk i
n,1 9 7 6
;H
a rm
,1 9 8 0
;V
e n o s a ,1 9 8 3
)
.P y
rim id i
n ed im
e r s a r ef
o rm
ed p
rim
a ri ly b
et w
e e n ad
j
a c e nt t h y m i
n e r e sid
u al
s o nt h
e s am
eD N A
s
t
r a nd
.R
ah
a n(
1 9 7 3
)
f
o u nd
t h
at
U V
i
r r ad i
at i
o n of
D N A
f
o rm
sp h
ot
op
r od
u ct
st h
at
d
i
s r up
t t h
eD N A
st
r u ct
u r e.T h
e s ug
a rp
h
o sp h
at
em
oi
ety
of
n u cl
ei
c a cid d
o e s n ot
sig
nif i
c a nt ly
ab
s o rb U V
ab
o v e2 2 0
nm
(
J
ag
g
e r,1 9 6 7
)
L
e s si
nf
o rm
at i
o n e xi
st
s o nt h
ep h
ot
o ch
em i
st
ry
of
ri b
o n u cl
ei
c a cid
.It
h
a sb
e e n n ot
ed t h
at p y
ri m id i
n eh y d
r at
e s a nd
u r a cil d i m
e r s a r ef
o rm
ed i
ni
r r ad i
at
ed R N A
.B
oth
of t h
e s ep
r od
u ct
s c a n c a u s eU
V i
n a cti
v at
io n o
f
R
N A
.O t h
e rp y
ri m id i
n ep h
ot
op
r od
u cts ha v e al
s ob
e e n ob
se r v ed
, alt h
o ug h
n o3
.6 Fa c to r sA
f fe ct ing
U V T re atm
e ntU V
ir r a
d ia
t io n
a s am
et h
od
of w
ate r
a nd w
a st
ew
ate r
d is
in
f
e cti
o nh
a s s e v e r al
l im it
at io n s
.W
it h
n o ch
em ic a
l
r e si d
u al
, a s e c o nd
a ry
d i
sin
f
e ct
a nt is
n e c e s s a ry t
op
r e v e nt
r eg
r ow t h w it h i
nt h
ed is
t
rib
ut io n s
y
st
em
a n
d p
r ote c
t
ag
ai
n st p
o st
-t
r e at m
e nt
c o n
t
am in a
t io n
.In
ad d it io n
, c u r r e nt U V
d is
in
f
e ct io n
t
e ch
n ol
og y
h
a s sh
ow
nli m ite
d
in a c
tiv a
t i
o n c ap
a cit y
ag
ai
n st
Gi
a rd i
a a nd C
ry p t
o sp
o rd i
um
cy
sts
at d
o s e st y
p
ic a
l ly
u s ed f
o rw
ate r a n
d
w
a st
ew
at
e rd is
in
f
e ct io n
.U V t
r a n sm itt
a n c e , a nd
c o n s eq
u e nt ly it g
e rm ic
id
al
e
f fi
cie n c
y
,is
d im in
i
sh
ed b y t
u rb id it y
, s u sp
e nd
ed
o rg
a nic
a nd i
n o rg
a nic
m
ate r
ia
l
H
ow
e v e r,U V d i
sin
f
e ct io n
of w
a st
ew
at
e r s e c o nd
a ry
ef fl
u e nt i
sg
ai
nin
g
s up p
o rt b
e c a u s et
ot
al
k
i ll
o ri
n a ct iv a
t
io n
of
p
at h
og
e n sis
n ot
r e
q
uir e
d
a nd
it i
s u n n e c e s s a ry
t
om
ain
t
ai
n a n a nt i m ic r o
b ia
l
ch
em ic a
l
r e s
id
u al
(
O l iv e r a n
d C
a r ey
,1 9 7 6 ;
W
olf
e,1 9 9 0
)
.In a
d d it io n
, a n ew m
et h
od
o
f U V d i
sin
f
e cti
o n,p
uls e
d
-
U V
l ig h t
,
h
a sb
e e n sh
ow
nt
od
el iv e r
i
nt
e n s ep
uls e s
of b
r o ad
sp
e ct
r um
U V
r ad i
at io n
s u ch t h
at
ad
o s e of 1 0 0 0 m
W
-s e c
/
cm
^is
d
el iv e r e
d
in
af
r a ct io n
of
a s e c o nd
a nd
w i ll
r ed
u c eC
ry
p
to s
p
o rdi
um
p
a r v um
o o cy
st
via
b i lit y
b y
3
-6
lo
g
i o(
D
u n n ,1 9 9 7
)
.S
e v e r al f
a ct
o r sm
u st
b
e c o n sid
e r ed
w h
e n ut i l i
zi
ng
U V
i
r r ad ia
t i
o nt
oin a c
t iv a
t
e of p
at h
og
e n sin
w
ate r
a nd w
a ste
w
at
e r, a nd t h
e s efa c
t
o r s a r ec o n s
