different types of sedimentation tanks https://civilengineers4you.blogspot.com

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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4. 1) Rectangular Tanks
2) Circular Tanks
3) Hopper Bottom Tanks
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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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