Bubble Volume Measurement Method Development
Procedure
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h1. Secondary Experiments h2. Procedure {float:right|border=2px solid black}[!SandFilterSetup2.png|hspace=5,width=600px!|First Sand Filter Setup with Bubble Collector] h5. First version of the experimental setup that included a bubble collector {float} |
Since
...
there
...
were
...
problems
...
with
...
the
...
DO
...
probes
...
we
...
used
...
in
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the
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initial
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experimental
...
setup,
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we
...
switched
...
to
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measuring
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the
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total
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volume
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of
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the
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bubbles
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that
...
form
...
inside
...
the
...
filter
...
column.
...
Using
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MathCad
...
,
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we
...
used
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the
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bubble
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volume
...
collected
...
to
...
calculate
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the
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equivalent
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DO
...
concentration
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removed
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from
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the
...
water.
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The
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only
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changes
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in
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the
...
setup
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were
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to
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remove
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the
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DO
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probes
...
and
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instead
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feed
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the
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water
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leaving
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the
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filter
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column
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into
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an
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inverted
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graduated
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cylinder.
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This
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cylinder
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was
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filled
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with
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water
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at
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the
...
start
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of
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each
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run
...
and
...
had
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its
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mouth
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submerged
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in
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water.
...
As
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bubbles
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formed
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in
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the
...
filter
...
media,
...
they
...
flowed
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out
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into
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this
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cylinder
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and
...
floated
...
to
...
the
...
top,
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displacing
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some
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water
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and
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causing
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the
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water
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level
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inside
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the
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cylinder
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to
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fall.
...
The
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air
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volume
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was
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measured
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every
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10
...
minutes
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during
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each
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run,
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using
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the
...
calibrations
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on
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the
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side
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of
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the
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cylinder.
...
We
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also
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tried
...
a
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new
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method
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of
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testing
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the
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quality
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of
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the
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effluent
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water,
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using
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sugar.
...
The
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sugar
...
test
...
involved
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collecting
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the
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outflowing
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water
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in
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a
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clear
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beaker
...
or
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cylinder
...
and
...
adding
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some
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sugar.
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As
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the
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sugar
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dissolved
...
in
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the
...
water,
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if
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tiny
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gas
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bubbles
...
were
...
seen
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floating
...
to
...
the
...
surface,
...
the
...
water
...
is
...
still
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super-saturated
...
with
...
gas
...
and
...
our
...
filter
...
method
...
did
...
not
...
work.
...
If
...
no
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bubbles
...
were
...
seen,
...
then
...
the
...
water
...
was
...
no
...
longer
...
super-saturated,
...
and
...
it
...
could
...
be
...
assumed
...
that
...
the
...
gases
...
were
...
removed.
Results
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{float h2. Results {float:right|border=2px solid black|width=500px} {anchor:Figure 1} !Fig.1, vol vs. time, 32 cm.png|width=500px,align=center! h5. Figure 1: Total gas volume removed from water vs. time by glass beads. Flow rate: 200 mL/min. Bed depth: 32 cm. {float} |
The
...
first
...
experiment
...
run
...
using
...
this
...
bubble
...
collection
...
method
...
used
...
glass
...
beads
...
as
...
the
...
filter
...
media,
...
with
...
a
...
flow
...
rate
...
of
...
200
...
ml/min
...
and
...
an
...
unsuspended
...
filter
...
depth
...
of
...
32
...
cm.
...
We
...
observed
...
that
...
the
...
performance
...
of
...
the
...
system
...
increased
...
for
...
about
...
20
...
minutes,
...
after
...
which
...
the
...
rate
...
of
...
the
...
increase
...
in
...
air
...
volume
...
became
...
relatively
...
constant.
...
These
...
results
...
are
...
illustrated
...
in
...
...
...
.
...
After
...
20
...
minutes,
...
the
...
line
...
of
...
gas
...
volume
...
vs.
...
time
...
becomes
...
nearly
...
linear.
...
We
...
concluded
...
that
...
the
...
experiment
...
needs
...
run
...
for
...
at
...
least
...
20
...
minutes
...
in
...
order
...
for
...
the
...
data
...
to
...
become
...
steady
...
and
...
reliable,
...
and
...
that
...
we
...
would
...
start
...
recording
...
data
...
after
...
at
...
least
...
20
...
minutes
...
of
...
runtime.
...
Since
...
the
...
graph
...
for
...
gas
...
volume
...
vs.
...
time
...
is
...
basically
...
linear,
...
we
...
could
...
accurately
...
fit
...
a
...
linear
...
trendline
...
to
...
the
...
data
...
using
...
Excel,
...
as
...
shown
...
in
...
...
...
.
...
The
...
slope
...
of
...
this
...
trendline
...
represents
...
the
...
rate
...
that
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the
...
gas
...
is
...
being
...
removed
...
from
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the
...
water,
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in
...
mL/min.
...
This
...
rate
...
can
...
be
...
converted
...
to
...
equivalent
...
mL
...
of
...
gas
...
removed
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per
...
liter
...
of
...
water
...
running
...
through
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the
...
filter
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column
...
by
...
dividing
...
the
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slope
...
of
...
the
...
line
...
by
...
the
...
flow
...
rate
...
in
...
L/min.
...
...
...
summarizes
...
this
...
process
...
for
...
the
...
first
...
run
...
with
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glass
...
beads.
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{float:left|border=2px solid black|width=500px}
{anchor:Table 1}
h5. Table 1: Gas removed by glass beads. Depth: 32 cm
||Flow Rate (mL/min)||Slope (mL/min)||Gas Removed (mL/L water)||
|200|.7727|3.86|
{float} |
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\\ \\ {float:right|border=2px solid black|width=500px} {anchor:Figure 2} !Fig.2, vol vs. time, 2 depths.png|width=500px,align=center! h5. Figure 2: Total gas volume removed from water vs. time by glass beads. Flow rate: 200 mL/min. Bed depths: 32 and 10 cm {float} |
Next,
...
we
...
experimented
...
with
...
the
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glass
...
bead
...
depth.
...
obtaining
...
the
...
results
...
shown
...
in
...
...
...
.
...
The
...
data
...
in
...
...
...
was
...
treated
...
the
...
same
...
way
...
as
...
for
...
the
...
first
...
trial
...
(
...
...
...
),
...
and
...
...
...
shows
...
the
...
resulting
...
gas
...
removal
...
for
...
each
...
bed
...
depth
...
in
...
mL
...
of
...
gas
...
per
...
L
...
of
...
water.
...
As
...
can
...
be
...
seen
...
in
...
the
...
table,
...
at
...
a
...
flow
...
rate
...
of
...
200
...
mL/min,
...
the
...
filter
...
depth
...
of
...
10
...
cm
...
appeared
...
to
...
remove
...
more
...
gas
...
than
...
the
...
larger
...
glass
...
bead
...
depth
...
of
...
32
...
cm.
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{float:left|border=2px solid black|width=500px}
{anchor:Table 2}
h5. Table 2: Gas removed by glass beads at varied depths
||Bed Depth (cm)||Flow Rate (mL/min)||Slope (mL/min)||Gas Removed (mL/L water)||
|10|200|4.9255|24.63|
|32|200|.78|3.9|
{float} |
This did not make sense, so we repeated the experiment later. #Figures 3 and 4 illustrate these results, showing that a larger filter depth did in fact extract a greater volume of dissolved gas at a faster rate.
| Anchor | ||||
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\\ \\ Logically, this did not make sense, so we repeated the experiment at a later date. [#Figures 3 and 4] illustrate these results, showing that a larger filter depth did in fact extract a greater volume of dissolved gas at a faster rate. {anchor:Figures 3 and 4} {float:left|border=2px solid black|width=1100px} |{anchor:Figure 5} !Fig. 3, vol vs. time, depths and flow rates.png|width=500px,align=center! h5. Figure 3: Gas volume vs. time at varying depths and flow rates.|{anchor:Figure 6} !Fig. 4, vol vs. time, depths adn flow rates 2.png|width=500px,align=center! h5. Figure 4: Gas volume vs. time at varying depths and flow rates. Excludes results of flow rate = 150 ml/min and depth = 33 cm.| {float} \\ \\ |
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{float:right|border=2px solid black|width=300400}
{anchor:Table 3}
h5. Table 3: Gas removed by glass beads at varied depths and flow rates
||Bed Depth (cm)||Flow Rate (mL/min)||Slope (mL/min)||Gas Removed (mL/L water)||
|33|200|.6268|3.14|
|10|200|.429|2.15|
|10|150|.3149|1.43|
{float}
|
As
...
shown
...
in
...
...
...
,
...
the
...
volume
...
of
...
gas
...
removed
...
from
...
the
...
water
...
flowing
...
at
...
150
...
mL/min
...
through
...
the
...
33
...
cm
...
filter
...
was
...
much
...
greater
...
than
...
that
...
removed
...
at
...
the
...
other
...
flow
...
rates
...
and
...
depths.
...
This
...
was
...
probably
...
because
...
the
...
33
...
cm
...
at
...
150
...
mL/min
...
run
...
was
...
after
...
the
...
10
...
cm
...
runs,
...
which
...
meant
...
we
...
needed
...
to
...
add
...
glass
...
beads
...
to
...
the
...
column.
...
A
...
lot
...
of
...
air
...
came
...
in
...
with
...
the
...
dry
...
beads,
...
and
...
we
...
most
...
likely
...
did
...
not
...
allow
...
sufficient
...
run
...
time
...
afterward
...
in
...
order
...
to
...
allow
...
all
...
the
...
trapped
...
air
...
to
...
escape
...
before
...
we
...
began
...
recording
...
the
...
data.
...
This
...
resulted
...
in
...
the
...
extremely
...
high
...
volumes
...
of
...
gas
...
apparently
...
being
...
removed
...
by
...
our
...
system.
...
By
...
the
...
time
...
we
...
ran
...
that
...
depth
...
at
...
the
...
lower
...
flow
...
rate,
...
the
...
extra
...
air
...
had
...
left
...
and
...
we
...
were
...
gathering
...
only
...
the
...
air
...
being
...
stripped
...
from
...
the
...
water
...
by
...
our
...
filter
...
column.
...
...
...
shows
...
the
...
same
...
results
...
as
...
#Figure 3 but omits the erroneous 150 mL/min
...
at
...
33
...
cm
...
data.
...
Clearly,
...
the
...
greater
...
filter
...
depth
...
resulted
...
in
...
the
...
removal
...
of
...
more
...
dissolved
...
gas
...
than
...
the
...
lower
...
depth.
...
The
...
flow
...
rate
...
was
...
not
...
varied
...
enough
...
to
...
have
...
much
...
impact
...
on
...
the
...
effectiveness
...
of
...
the
...
filter
...
method.
...
Trendlines
...
were
...
once
...
again
...
fitted
...
to
...
the
...
gas
...
volume
...
vs.
...
time
...
curves
...
in
...
...
...
,
...
and
...
the
...
resulting
...
gas
...
removals
...
are
...
shown
...
in
...
...
3.
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]. \\ {float:right|border=2px solid black|width=500px} {anchor:Figure 5} !Fig.5, DO red. rate vs. time, no outlier.png|width=500px! h5. Figure 5: DO reduction rate vs.time at varying depths and flow rates. {float} |
We
...
also
...
used
...
our
...
Mathcad
...
program
...
to
...
convert
...
the
...
volume
...
of
...
gas
...
we
...
were
...
collecting
...
to
...
an
...
equivalent
...
concentration
...
of
...
dissolved
...
oxygen
...
being
...
removed
...
from
...
the
...
water.
...
...
...
shows
...
the
...
results
...
of
...
this
...
for
...
the
...
three
...
runs
...
shown
...
in
...
...
...
.
...
These
...
values
...
for
...
DO
...
removal
...
could
...
not
...
be
...
taken
...
as
...
accurate,
...
however,
...
because
...
the
...
Mathcad
...
program
...
assumes
...
that
...
oxygen
...
is
...
the
...
only
...
gas
...
super-saturating
...
the
...
water.
...
In
...
reality,
...
other
...
gases
...
such
...
as
...
nitrogen
...
could
...
be
...
present.
...
Though
...
the
...
values
...
are
...
not
...
exact,
...
their
...
relative
...
positions
...
on
...
the
...
graph
...
may
...
be
...
used
...
to
...
draw
...
some
...
conclusions.
...
...
...
shows
...
that
...
the
...
rate
...
of
...
dissolved
...
oxygen
...
removal
...
increased
...
for
...
a
...
short
...
amount
...
of
...
time
...
at
...
the
...
start
...
of
...
each
...
run,
...
but
...
then
...
tended
...
to
...
level
...
off
...
into
...
a
...
steady
...
removal
...
rate
...
as
...
time
...
went
...
on.
...
The
...
higher
...
rate
...
of
...
DO
...
reduction
...
exhibited
...
by
...
the
...
run
...
of
...
the
...
deeper
...
bed
...
depth
...
(33cm)
...
shows
...
again
...
that
...
a
...
deeper
...
bed
...
is
...
more
...
effective.
| Wiki Markup |
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[Download data for Figures 1-5 here|First Results using a Bubble Collector^Initial Bubble Collector Results.xls]\\ {float:right|border=2px solid black|width=500px} {anchor:Figure 6} !DO removed, measured and calculated, 10cm33cm.png|width=500px! h5. Figure 6: DO removed, measured by the DO probes as well as by calculating equivalent DO using the collected bubble volume. Sand depth of 10 cm, flow rate of 200 mL/min. {float} [ |
...
...
compares
...
the
...
DO
...
removal
...
as
...
measured
...
by
...
the
...
DO
...
probes
...
to
...
our
...
calculations
...
using
...
the
...
total
...
collected
...
bubble
...
volume
...
for
...
the
...
200
...
mL/min
...
run
...
at
...
10
...
cm
...
depth.
...
The graph reveals a large discrepancy between the DO probes' data and the numbers derived from the actual volume of water collected. Again,
...
although
...
the
...
calculated
...
DO-removal
...
values
...
cannot
...
be
...
trusted
...
for
...
accuracy,
...
the
...
overall
...
trend
...
of
...
the
...
numbers
...
can
...
be
...
used
...
for
...
comparison. The negative DO reduction measured by the DO probes would mean that oxygen was added to the water inside the filter column, although the increasing volume of air collected from the water showed that the opposite was true. We concluded from this that our DO probes were definitely not reliable.
The sugar test was performed after several of the runs, but the results varied greatly, even when performed on multiple effluent samples for the same run, or on tap water. Overall, the sugar test results were inconclusive.
Download data for these experiments here
Conclusion
From these results, we may tentatively conclude that greater filter depth removes more dissolved oxygen. However, the method of measuring and recording the volume of gas removed from the water was not precise, and it allowed for a large amount of error and inconsistency. We also cannot be sure that water entering the system was in fact supersaturated, as the temperature outside was growing warmer and varying greatly by the day. As such, we will be able to draw firmer conclusions when the setup includes a method of supersaturating the water and a more accurate and precise method of measuring the collected air volume.
The sugar test proved to be very inconsistent, but it may perform better if a finer sugar is used. This method requires further testing.
After this round of experiments, we altered our setup to include a new bubble collector and a chamber to make sure the water is super-saturated when entering our filter. See the method and results here.