Civil Engineering - Waste Water Engineering

11. 

Pick up the incorrect statement from the following for allowing workers to enter sewers

A. The particular manhole and one manhole on up stream and one manhole on down stream should remain open for 30 minutes
B. Proper tests for the presence of poisonous gases must be carried out
C. The men entering the manhole should be advised to smoke in the sewer
D. Warning signals should be erected
E. None of these.

Answer: Option C

Explanation:

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12. 

The settling velocity of a spherical particle of diameter less than 0.1 mm as per Stock's law, is

A.
B.
C.
D.

Answer: Option B

Explanation:

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13. 

In a grit chamber of a sewage treatment plant,

A. flow velocity 0.15 m to 0.3 m/sec is kept
B. depth of 0.9 m to 1.20 m is kept
C. one minute of detention period is kept
D. all the above.

Answer: Option D

Explanation:

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14. 

The rate of accumulation of sludge per person per year, is

A. 10 litres
B. 15 litres
C. 20 litres
D. 25 litres
E. 30 litres.

Answer: Option C

Explanation:

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15. 

The disintegrating pump in which solid matter is broken up before passing out, is

A. centrifugal pump
B. reciprocating pump
C. pneumatic ejector
D. none of these.

Answer: Option A

Explanation:

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