1. Topic : Types Of Sedimentation Tank
By : Sagar K. Vekariya
2. The process of sedimentation is designed to
remove large particles of contamination from
water and wastewater.
Sedimentation tanks can be installed before or
after water and wastewater completes the
treatment process.
Sedimentation tanks are also known as settling
tanks or wastewater clarifiers.
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5. These are rectangular in
plan and consists of
large number of baffle
walls.
The function of baffle
wall is to reduce the
velocity of incoming
water.
Openings are given in
baffle walls at different
height.
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6. Continuous flow in tank.
Supervision & labor work is less.
Less head loss due to outlet given at the top of
tank.
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7. Tanks are arranged in series so it is easy to
maintenance of one(any one).
Because of continuous flow in tank time waste
rate is low.
To store pure water there is no necessity of
tank, so construction cost is less.
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8. Circular sedimentation tank is costly at the
view of construction.
For dispose the sludge mechanical scraper
available at bottom of the tank.
Over flow rate of this type of tank is 1500
lit/hour/m2.
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9. I. Radial flow
II. Spiral flow
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10. The water enters in this tank through the
central pipe placed in-side the deflector box.
Mostly to reduce the velocity of flow there is
provide circular baffle box.
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11. All the impurities settled at the base of tank.
The sludge is removed by scraper(known as
raking arm).which continuously move around
the floor at very small velocity.
The maximum velocity of raking arm does not
exceed 4.5 m/h.
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12. Water enters through
the vertical silt.
There is raking arm
with blades in the
tank, which is allows
the water move along
the circumference of
the tank.
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13. While water moving at very low velocity allows
its suspended impurities to settle in the tank,
which can be remove from sludge outlet.
The clear water drawn from outlet pipe.
The length of outlet is not exceed 1/8
circumference of the tank.
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14. The shape of the base of this tank is hopper type.
This are vertical flow tanks, because water flows
upward & downward in these tank.
The water enters in this tank from top inlet channel.
Because of deflector box water flows from upper to
lower.
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15. Impurities settled at
the bottom of the
tank.
Pure water taken by
draw off channel.
Sludge outlet pipe is
used to take out the
sludge from tank.
Over flow rate = 2000
lit/hour/m2
Detention period = 3
– 4 hours
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