Water Supply Engineering - Multiple Choice Questions

Water Supply Engineering Multiple Choice Questions

 1. Imhoff cone is used to measure________________?. 

A. Total organic solids

B. Total solids

C. Total in organic solids

D. Settleable solids

Answer = Settleable solids 

2. The grit and silt of the grit chambers, may not be used for_________________?. 

A. Raising low lying areas by dumping

B. Concreting

C. Both A. and B.. 

D. Neither A. nor B. 

Answer = Concreting

3. If the diameter of a sewer is 150 mm, the gradient required for generating self cleansing velocity, is________________?. 

A. 1 in 60

B. 1 in 100

C. 1 in 120

D. None of these. 

Answer = 1 in 100

4. The sewage treatment units in which anaerobic decomposition of organic matter is used, are called________________?. 

A. Imhoff tanks

B. Trickling filters

C. Sludge sedimentation tanks

D. None of these. 

Answer = Trickling filters

5. If the flame of a miner's safety lamp in a manhole extinguishes within 5 minutes, the sewer certainly contains_______________?. 

A. Hydrogen sulphide

B. Carbon dioxide

C. Methane

D. Oxygen. 

Answer = Carbon dioxide

6. If the depth of flow in a circular sewer is 1/4th of its diameter D, the wetted perimeter is______________?. 

A. /2

B. /4

C. /3

D. D. 

Answer = /3

7. If q is the average sewage flow from a city of population P, the maximum sewage flow______________?. 

A. Q = [(4 + )/(18 + )] q

B. Q = [(18 + P)/(4 + )] q

C. Q = [(18 + )/(4 + )] q

D. Q = [(5 + )/((15 + )] q. 

Answer = Q = [(18 + )/(4 + )] q

8. For a grit chamber, if the recommended velocity of flow is 0.2 m/sec and detention period is 2 minutes, the length of the tank, is__________________?. 

A. 16 m

B. 20 m

C. 24 m

D. 30 m. 

Answer = 24 m

9. The sewer that unloads the sewage at the point of treatment is called_________________?. 

A. Main sewer

B. Outfall sewer

C. Branch sewer

D. House sewer. 

Answer = Outfall sewer

10. Sewer pipes are designed for maximum discharge with 25% to 33% vacant cross-sectional area for__________________?. 

A. Unexpected large scale infiltration of stream water

B. Unexpected increase in the population

C. Under estimates of maximum and average flows

D. All of the above. 

Answer = All of the above

11. At the junction of sewers___________________?. 

A. Top of smaller sewer is kept lower

B. Top of larger sewer is kept lower

C. Tops of both the sewers are at the same level

D. None of these. 

Answer = None of these

12. The normal values of over flow rates for sedimentation tanks using coagulant, ranges between__________________?. 

A. 25,000 to 35,000 litres/sqm/day

B. 40,000 to 50,000 litres/sqm/day

C. 50,000 to 60,000 litres/sqm/day

D. 80,000 to 100,000 litres/sqm/day. 

Answer = 50,000 to 60,000 litres/sqm/day

13. To prevent settling down of sewage both at the bottom and on the sides of a large sewer, self-cleaning velocity recommended for Indian conditions, is_________________?. 

A. 0.50 m/sec

B. 0.60 m/sec

C. 0.70 m/sec

D. 0.75 m/sec. 

Answer = 0.75 m/sec

14. Pick up the incorrect statement from the following for allowing workers to enter sewers_______________?. 

A. The particular manhole and one manhole on upstream and one manhole on downstream 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. 

Answer = The men entering the manhole should be advised to smoke in the sewer

15. The settling velocity of the particles larger than 0.06 mm in a settling tank of depth 2.4 is 0.33 m per sec. The detention period recommended for the tank, is____________________?. 

A. 30 minutes

B. 1 hour

C. 1 hour and 30 minutes

D. 2 hours. 

Answer = 2 hours

16. The discharge per unit plan area of a sedimentation tank, is generally called________________?. 

A. Over flow rate

B. Surface loading

C. Over flow velocity

D. All the above

Answer = All the above 

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