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Subject :NSO    Class : Class 7

The steps of wastewater treatment plant are given below randomly.
(i) Wastewater is passed into sedimentation tank.
(ii) Sludge is decomposed by anaerobic bacteria.
(iii) Wastewater is passed through bar screens.
(iv) Wastewater is passed to grit and sand removal tank.
(v) Solids settle at the bottom and floatable materials are removed by skimmer.
(vi) Aeration of water takes place.
(vii) Disinfection of water by adding chlorine.
Which of the following represents correct sequence of steps?

A (iii) → (iv) → (i) → (v) → (ii) → (vi) → (vii)
B (iv) → (iii) → (i) → (v) → (ii) → (vi) → (vii)
C (iii) → (iv) → (v) → (i) → (ii) → (vi) → (vii)
D (iii) → (iv) → (i) → (ii) → (v) → (vi) → (vii)

Ans 1:

Class : Class 8

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