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
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were
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problems
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with
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the
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DO
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probes
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we
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used
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in
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the
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initial
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experimental
...
setup,
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we
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switched
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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
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form
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inside
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the
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filter
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column.
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Using
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MathCad
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,
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we
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used
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the
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bubble
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volume
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collected
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to
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calculate
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the
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equivalent
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DO
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concentration
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removed
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from
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the
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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
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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
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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
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start
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of
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each
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run
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and
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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.
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As
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bubbles
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formed
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in
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the
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filter
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media,
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they
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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
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floated
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to
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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
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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
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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
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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.
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The
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sugar
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test
...
involved
...
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
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or
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cylinder
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and
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adding
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some
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sugar.
...
As
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the
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sugar
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dissolved
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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
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were
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seen
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floating
...
to
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the
...
surface,
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the
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water
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is
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still
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super-saturated
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with
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gas
...
and
...
our
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filter
...
method
...
did
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not
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work.
...
If
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no
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bubbles
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were
...
seen,
...
then
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the
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water
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was
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no
...
longer
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super-saturated,
...
and
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it
...
could
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be
...
assumed
...
that
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the
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gases
...
were
...
removed.
Results
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{float h2. Results {float:right|border=2px solid black|width=600px500px} |{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.|{anchor:Table 1} {float} |
The
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first
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experiment
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run
...
using
...
this
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bubble
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collection
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method
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used
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glass
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beads
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as
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the
...
filter
...
media,
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with
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a
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flow
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rate
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of
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200
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ml/min
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and
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an
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unsuspended
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filter
...
depth
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of
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32
...
cm.
...
We
...
observed
...
that
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the
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performance
...
of
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the
...
system
...
increased
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for
...
about
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20
...
minutes,
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after
...
which
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the
...
rate
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of
...
the
...
increase
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in
...
air
...
volume
...
became
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relatively
...
constant.
...
These
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results
...
are
...
illustrated
...
in
...
...
...
.
...
After
...
20
...
minutes,
...
the
...
line
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of
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gas
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volume
...
vs.
...
time
...
becomes
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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
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at
...
least
...
20
...
minutes
...
of
...
runtime.
...
Since
...
the
...
graph
...
for
...
gas
...
volume
...
vs.
...
time
...
is
...
basically
...
linear,
...
we
...
could
...
accurately
...
fit
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a
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linear
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trendline
...
to
...
the
...
data
...
using
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Excel,
...
as
...
shown
...
in
...
...
...
.
...
The
...
slope
...
of
...
this
...
trendline
...
represents
...
the
...
rate
...
that
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the
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gas
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is
...
being
...
removed
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from
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the
...
water,
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in
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mL/min.
...
This
...
rate
...
can
...
be
...
converted
...
to
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equivalent
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mL
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of
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gas
...
removed
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per
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liter
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of
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water
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running
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through
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the
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filter
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column
...
by
...
dividing
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the
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slope
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of
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the
...
line
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by
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the
...
flow
...
rate
...
in
...
L/min. #Table 1 summarizes this process for the first run with glass beads.
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[#Table 1] summarizes this process for the first run with glass beads. {float:left|border=2px solid black|width=300px500px} {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} \\ \\ Next, we experimented with the glass bead depth. obtaining the results shown in [#Figure 2]. The data in [#Figure 2] was treated the same way as for the first trial ([#Figure 1]), and [#Table 2] 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: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 glass bead depth. obtaining the results shown in #Figure 2. The data in #Figure 2 was treated the same way as for the first trial (#Figure 1), and #Table 2 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=1000px500px}
|{anchor:FigureTable 2}
!Figh5.2, vol vs. time, 2 depths.png|width=500px!
h5. Figure 2: Total gas volume removed from water vs. time 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.
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Flow rate: 200 mL/min. Bed depths: 32 and 10 cm.|{anchor:Table 2} h5. Table 2: Gas removed by glass beads at varied depths {table:align=center} ||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| {table}| {float} \\ \\ 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. ThisExcludes graphresults isof theflow samerate as= Figure 3, but excludes the results from the flow rate of 150 ml/min at 33 cm filter depth150 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}
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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
...
...
...
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
...
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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.
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{float:right|border=2px solid black|width=500px} {anchor:Figure 6} !DO removed, measured and calculated, 33cm.png|width=500px! h5. Figure 6: DO removed, rate of DO reduction exhibited by the run of the deeper bed depth (33cm) shows again that a deeper bed is more effective. \\ {float:right|border=2px solid black|width=500px} {anchor:Figure 6} !DO removed, measured and calculated, 10cm.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} [#Figure 6] compares the DO removal as measured by the DO probes toas ourwell calculationsas usingby thecalculating totalequivalent collected bubble volume for the 200 mL/min run at 10 cm depth. Again, although the calculated DO-removal values cannot be trusted for accuracy, the overall trend of the numbers can be used for comparison. [#Figure 6] reveals a large discrepancy between the DO probes' data and the numbers derived from the actual volume of water collected. The negative difference between the inflow and outflow DO recorded by the DO probes would mean that oxygen was _added_ to the water during the process, although the increasing volume of air collected from the water is evidence of the opposite. We concluded from this that our DO probes were definitely not reliable. The sugar test was performed after several 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. \\ h2. 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.|Current Experiments]DO using the collected bubble volume. Sand depth of 10 cm, flow rate of 200 mL/min. {float} |
#Figure 6 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.