Biology
Grade-7
Easy
Question
The various stages of cleaning wastewater in a sewage treatment plant are as follows. Select the stages in chronological order. (create)
A. Wastewater goes to a grit and sand removal tank.
B. The water is allowed to settle in a large tank which is sloped towards the middle.
C. Air is pumped into the clarified water to help aerobic bacteria to grow.
D. Wastewater is passed through bar screens. Large objects like plastics, cans, rags, sticks, napkins, etc., are removed.
- A, C, D, B
- D, C, B, A
- D, A, B. C
- C, A, B, D
Hint:
- Sewage water treatment is a process to clean wastewater step by step and it starts from removal of large waste material to smaller.
The correct answer is: D, A, B. C
D,A,B,C
- The first step in waste water treatment is to remove big waste matter like napkins, plastics, cans etc.
- Then wastewater goes to grit and sand removal tank .
- Then the water is allowed to settle in a large tank which is sloped towards the middle.
- Air is pumped into the clarified water to help aerobic bacteria to grow.
- Aerobic bacteria helps to remove smallest waste particles from water as they feed on that.
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