
78-1
78.1 Introduction
Maintaining and verifying water quality is important in many environmental applications. e most
obvious is in drinking water applications, but industrial and municipal wastewater, natural surface/
groundwater,
in
dustrial
pr
ocess
wa
ters,
an
d
cl
osed-loop
co
ntrol
sy
stems
al
l
re
quire
a ce
rtain
ra
nge
or
ma
ximum
co
ncentration
of sp
ecies
to op
erate
pr
operly
. e
refore,
th
e
de
velopment
of in
strumentation
fo
r
mo
nitoring
an
d
de
tecting
th
ese
co
ntaminants
is a hi
ghly
co
mpetitive
ar
ea
. Of co
urse,
th
e
ch
emical
sp
ecies
of in
terest
de
pend
on th
e
ul
timate
us
e
of th
e
wa
ter,
bu
t
th
is
se
ction
de
als
wi
th
so
me
of th
e
wa
ter
qu
ality
s
ensors
a