Types of sedimentation tank

different types of sedimentation tanks

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1. Water Supply & Sanitary Engineering Topic : Types Of Sedimentation Tank By : Sagar K. Vekariya

2. Sedimentation 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. 29/04/2017 2 WATER SUPPLY & SANITARY ENGINEERING

3. Water Treatment Plant Lay - Out 29/04/2017 3 WATER SUPPLY & SANITARY ENGINEERING

4. Types Of Sedimentation Tank Rectangular Tanks Circular Tanks Hopper Bottom Tanks 29/04/2017 4 WATER SUPPLY & SANITARY ENGINEERING

5. Rectangular Tanks 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. 29/04/2017 5 WATER SUPPLY & SANITARY ENGINEERING Continuo…

6. Advantages :- Continuous flow in tank. Supervision & labor work is less. Less head loss due to outlet given at the top of tank. 29/04/2017 6 WATER SUPPLY & SANITARY ENGINEERING

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. 29/04/2017 7 WATER SUPPLY & SANITARY ENGINEERING

8. Circular Tank 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/m 2 . 29/04/2017 8 WATER SUPPLY & SANITARY ENGINEERING

9. There is two types of flow possible in the tank: Radial flow Spiral flow 29/04/2017 9 WATER SUPPLY & SANITARY ENGINEERING

10. Radial flow 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. 29/04/2017 10 WATER SUPPLY & SANITARY ENGINEERING Continuo…

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. 29/04/2017 WATER SUPPLY & SANITARY ENGINEERING 11

12. Spiral flow 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. 29/04/2017 12 WATER SUPPLY & SANITARY ENGINEERING Continuo…

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. 29/04/2017 WATER SUPPLY & SANITARY ENGINEERING 13

14. Hopper Bottom Tanks 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. 29/04/2017 14 WATER SUPPLY & SANITARY ENGINEERING Continuo…

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/m 2 Detention period = 3 – 4 hours 29/04/2017 WATER SUPPLY & SANITARY ENGINEERING 15