*** This version of Confluence is for testing only and contains a copy of content from June 29th 2026. No changes will be preserved. ***
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!lamella.jpg|width=300px!
h5. Figure 1: Front of a sedimentation tank at the Cuatro Communidades plant
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h2. |
Introduction
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and
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Objectives
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The
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Four
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Communities
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plant
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was
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designed
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with
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shallower
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sedimentation
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tanks
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than
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those
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of
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Ojojona
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and
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Tamara.
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To
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determine
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the
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effects
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of
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the
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design
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changes
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the
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plant
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effluent
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turbidity
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was
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compared
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to
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the
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turbidity
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coming
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out
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of
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a
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tube
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settler
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at
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the
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end
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of
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the
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flocculator.
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The
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tube
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settler
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was
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designed
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to
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act
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as
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a
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model
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sedimentation
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tank.
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If
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the
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sedimentation
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tanks
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were
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working
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efficiently,
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the
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plant
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effluent
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turbidity
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should
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have
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been
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equal
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to
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or
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less
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than
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the
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turbidity
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coming
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out
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of
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the
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tube
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settler.
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Additionally,
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flocs
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were
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observed
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to
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be
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settling
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out
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in
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the
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channel
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carrying
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water
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from
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the
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flocculator
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to
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the
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sedimentation
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tanks
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and
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very
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few
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were
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reaching
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the
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second
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tank.
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To
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determine
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what
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effect,
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if
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any,
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the
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uneven
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distribution
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of
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flocs
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had
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on
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the
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two
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tanks,
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the
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effluent
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turbidities
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from
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both
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tanks
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were
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compared.
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Samples
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were
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taken
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from
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within
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the
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effluent
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launders
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of
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both
...
tanks.
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{float:right|border=2px solid black|width=240px} !tubesettler1.jpg|width=240px! h5. Figure 2: Tube settler {float} h2. Methods To compare ideal sedimenation with actual sedimentation in the plant, a tube settler was placed at the end of the flocculation tank (Figure 2). The [tube settler design] mimicked the design of the lamella in the sedimentation tanks except that the tube settler was a much simpler system. The effluent from the tube settler was compared to the effluent from the sedimentation tanks. Turbidity measurements were taken in twenty minute or half hour intervals over the course of several hours and averaged when the influent, effluent, and alum dose were relatively constant. h2. Results and Discussion The results of each test of the effluent from both the tube settler and the sedimentation tanks are shown below in figure 3. The effluent |
Methods
To compare ideal sedimenation with actual sedimentation in the plant, a tube settler was placed at the end of the flocculation tank (Figure 2). The tube settler design (See Methods Section) mimicked the design of the lamella in the sedimentation tanks except that the tube settler was a much simpler system. The effluent from the tube settler was compared to the effluent from the sedimentation tanks. Turbidity measurements were taken in twenty minute or half hour intervals over the course of several hours and averaged when the influent, effluent, and alum dose were relatively constant.
Results and Discussion
The results of each test of the effluent from both the tube settler and the sedimentation tanks are shown below in figure 3. The effluent turbidity is compared to the incoming raw water turbidity.
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turbidity is compared to the incoming raw water turbidity. {float:border=2px solid black|width=600px} !Sedgraph.gif|width=600px! h5. Figure 3 {float} |
The
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effluent
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turbidity
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from
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the
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sedimentation
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tanks
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and
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the
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tube
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settlers
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were
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fairly
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similar
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at
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all
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incoming
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turbidities
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although
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the
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tube
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settlers
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generally
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performed
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better.
...
The
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largest
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difference,
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1
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NTU
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between
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the
...
two
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was
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at
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a
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raw
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water
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turbidity
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of
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135
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NTU.
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Most
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of
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the
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tests
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began
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in
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the
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morning
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and
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the
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incoming
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plant
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turbidity
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was
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decreasing
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throughout
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the
...
day.
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This
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decrease
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was
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measured
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first
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in
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the
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tube
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settlers
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biasing
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the
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tube
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settler
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measurements
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lower
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than
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the
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sedimentation
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tank
...
measurements.
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There
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was
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very
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little
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difference
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between
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the
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two
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sedimentation
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tanks.
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In
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the
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other
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trials,
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one
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tank
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does
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not
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perform
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consistently
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better
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or
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worse.
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The
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tests
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were
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taken
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when
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the
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plant
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was
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performing
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well-
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the
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effluent
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close
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to
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or
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below
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5
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NTU.
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The
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test
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would
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be
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more
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informative
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when
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the
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plant
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was
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not
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working
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well
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but
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flocs
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were
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forming.
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In
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this
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case
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the
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test
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could
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show
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whether
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the
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flocculator
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or
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the
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sedimentation
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tanks
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were
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performing
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poorly.
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