Civil Engineering - Waste Water Engineering

26. 

Pick up the correct statement from the following :

A. Small sewers are cleaned by flushing
B. Medium sewers are cleaned by cane rodding
C. Medium sewers may be cleaned by pills
D. Large sewers are cleaned by removing the deposited materials
E. All the above.

Answer: Option E

Explanation:

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27. 

Cement concrete sewers are only suitable if non-scouring velocity is between

A. 2.5 to 3.0 m/sec
B. 3.0 to 4.0 m/sec
C. 3.5 to 4.5 m/sec
D. 4.5 to 5.5 m/sec.

Answer: Option A

Explanation:

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28. 

The grit chambers of sewage treatment plants, are generally cleaned after

A. 2 days
B. 5 days
C. 7 days
D. 12 days
E. 14 days.

Answer: Option E

Explanation:

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29. 

The spacing of bars for perforations in coarse screens used for the treatment of sewage, is

A. 20 mm
B. 30 mm
C. 40 mm
D. 50 mm
E. 100 mm.

Answer: Option D

Explanation:

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30. 

In very first stage of decomposition of the organic matter in sewage

A. nitrites are formed
B. nitrates are formed
C. carbondioxide is formed
D. ammonia is formed.

Answer: Option D

Explanation:

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