Chromatewasteisconcentratedbyevaporationinaseriesofshallowflowthroughreactortanks connectedbyashortlengthofpipe.

Chromate
waste
is
concentrated
by
evaporation
in
a
series
of
shallow
flow
through
reactor
tanks
 connected
by
a
short
length
of
pipe.
The
first
tank
in
the
series
has
a
volume
of
4500
ft3
and
a
 residence
time
(for
water)
of
2
hours.
The
second
tank
also
has
a
volume
of
4500
ft3.

The
 evaporation
rate
is
about
1/16
of
the
volume
of
each
tank
per
hour.

50
moles/hour
of
chromate
 (CrO42‐),
along
with
water,
enters
the
first
tank.
Assume
that
CrO42‐
does
not
volatilize
(i.e.,
it
 remains
with
the
liquid
water
at
all
times)
and
is
conservative.

If
both
tanks
are
well‐mixed
and
 remain
at
constant
volume,
what
is
the
steady‐state
concentration
(in
mg/L)
of
chromate
(CrO42‐)
in
 the
effluent
water
leaving
the
second
tank