Tube Settlers
| Wiki Markup |
|---|
h1. Tube Settlers {float} !tubeset.jpg|thumbnail! {float} |
Tube
...
settlers
...
are
...
used
...
to
...
test
...
effluent
...
turbidity
...
at
...
different
...
locations.
...
The
...
tube
...
settlers
...
were
...
designed
...
to
...
mimic
...
the
...
sedimentation
...
tank
...
that
...
would
...
traditionally
...
follow
...
the
...
flocculator.
...
Tube
...
settlers
...
were
...
chosen
...
because
...
they
...
provide
...
an
...
inexpensive
...
way
...
to
...
sample
...
and
...
create
...
a
...
minimal
...
disturbance
...
within
...
in
...
the
...
tank.
...
Using
...
this
...
method,
...
different
...
locations
...
of
...
the
...
tank
...
can
...
be
...
sampled.
...
Data
...
gathered
...
can
...
be
...
used
...
to
...
assess
...
how
...
each
...
stage
...
of
...
the
...
tank
...
is
...
affecting
...
the
...
final
...
effluent
...
turbidity.
...
The
...
three
...
glass
...
tube
...
settlers
...
used
...
were
...
of
...
60
...
cm
...
length
...
and
...
2.5
...
cm
...
diameter.
...
A
...
peristaltic
...
pump
...
was
...
used
...
to
...
transport
...
the
...
water
...
to
...
the
...
three
...
turbidimeters.
...
Once
...
the
...
equipment
...
was
...
gathered,
...
the
...
next
...
step
...
was
...
to
...
design
...
the
...
flow
...
rate
...
for
...
the
...
peristaltic
...
pump.
...
The
...
assumptions
...
used
...
in
...
the
...
calculation
...
for
...
the
...
flow
...
rate
...
were
...
that
...
the
...
optimum
...
angle
...
for
...
tube
...
settler
...
is
...
60°
...
and
...
the
...
critical
...
velocity
...
is
...
10
...
m/day.
...
Sixty
...
degrees
...
is
...
used
...
because
...
it
...
is
...
the
...
angle
...
at
...
which
...
the
...
distance
...
required
...
for
...
floc
...
settling
...
is
...
minimized
...
and
...
still
...
allows
...
the
...
solids
...
that
...
settled
...
on
...
the
...
side
...
of
...
the
...
tube
...
to
...
slide
...
down.
...
The
...
critical
...
velocity
...
is
...
taken
...
from
...
a
...
range
...
of
...
accepted
...
values
...
and
...
has
...
been
...
found
...
to
...
be
...
the
...
critical
...
velocity
...
in
...
previous
...
plants
...
in
...
Honduras.
...
The
...
flow
...
rate
...
was
...
calculated
...
using
...
the
...
following
...
equations.
...
Schematic
...
of
...
the
...
Data
...
Collecting
...
Tube Settlers
| Wiki Markup |
|---|
Settlers {float} !tubesetschem.jpg|thumbnail! {float} |
Dimensions
...
and
...
Variables
...
chosen:
...
- b
...
- =
...
- diameter
...
- =
...
- 2.5
...
- cm
...
- L
...
- =
...
- length
...
- of
...
- the
...
- tube
...
- settler
...
- =
...
- 60
...
- cm
...
- alpha
...
- =
...
- optimum
...
- angle
...
- =
...
- 60°
| Include Page | ||||
|---|---|---|---|---|
|
| Include Page | ||||
|---|---|---|---|---|
|
The following equations were adopted from Shultz and Okun for determining critical velocity for up flow through a tube. The flow rate calculated for our initial configuration was 44 mL/min. There is a linear relationship between pump speed and the flow rate through the settling tube. The flow rate though the settling tube also has a linear relationship to the critical velocity of the sedimentation process in the tube. It is important to note that the critical velocity of the settling tubes is the same as the critical velocity that can be found in the sedimentation tanks at Ojojona.
The setup of the tube settlers in the tank was the next design step. Originally the tube settlers were to be hung from the edge of the tanks at designated locations. On further inspection however, when laid between the baffles on top of the connectors they are at the correct angle and so can easily be relocated and do not require any attachment to the tank.
The final design consists of the tube settlers nestled between the baffles, and then connected to the peristaltic pump. The peristaltic pump pulls water from the peristaltic pump at the correct velocity and the water is routed through a turbidimeter in order to measure the turbidity. Also installed is a turbidimeter that measures the influent turbidity of the water before it reaches the tank. The turbidimeter is gravity fed.