Multiple Choice Exam Questions on Waste Water Engineering - Set 12 - ObjectiveBooks

# Practice Test: Question Set - 12

1. Pick up the correct statement from the following:
(A) The materials separated by screens, is called screenings
(B) The screenings are disposed off either by burning or by burial or by dumping
(C) The process of burning the screenings, is known as compositing
(D) All the above

2. Which one of the following gases is most significant as air pollutant?
(A) Carbondioxide
(B) Oxygen
(C) Nitrogen
(D) Sulphur-dioxide

3. Hazen's formula VS = 418 (GS - Gw)d [(3T + 70)/100] is used for the settlement velocity of the particles of diameter
(A) Less than 0.01 mm
(B) Less than 0.05 mm
(C) Less than 0.1 mm
(D) Greater than 0.1 mm

4. For sewers, inverted siphon is provided for
(A) One pipe
(B) Two pipes
(C) Three pipes
(D) Four pipes

5. Pick up the correct statement from the following:
(A) pH value indicates acidity and alkalinity of sewage
(B) In acidic sewage, the pH value is less than 7
(C) In alkaline sewage, the pH value is more than 7
(D) All the above

6. For large sewers, maximum distance between manholes may be
(A) 50 m
(B) 100 m
(C) 200 m
(D) 300 m

7. In sewers designed with self cleansing velocity,
(A) The bottom is silted
(B) The bottom is scoured
(C) Both silting and scouring occur at the bottom
(D) Neither silting nor scouring occurs at the bottom

8. The value of Chezy's constant C = 157.6/(1.81 + K/√r) is used in
(A) Chezy's formula
(B) Bazin's formula
(C) Kutter's formula
(D) Manning's formula

9. An inverted siphon is designed generally for
(A) One pipe
(B) Two pipes
(C) Three pipes
(D) Four pipes

10. The spacing of bars of perforations of fine screens used for the treatment of sewage, is
(A) 2 to 3 mm
(B) 3 to 5 mm
(C) 5 to 8 mm
(D) 8 to 10 mm

11. Pathogens (or pathogenic bacterias) in water may cause
(A) Typhoid
(B) Cholera
(C) Dysentery
(D) All the above

12. The rate of accumulation of sludge per person per year, is
(A) 10 liters
(B) 15 liters
(C) 20 liters
(D) 25 liters

13. The screens are fixed
(A) Perpendicular to the direction of flow
(B) Parallel to the direction of flow
(C) At an angle 30° to 60° to the direction of flow
(D) None of these

14. In circular sewers if depth of flow is 0.2 times the full depth, the nominal gradient,
(A) Is only provided
(B) Is doubled
(C) Is trebled
(D) Is not enough

15. In detritus tanks,
(A) Flow velocity is kept 0.09 m/sec
(B) Detention period is kept 3 to 4 minutes
(C) Organic and inorganic materials are separated
(D) All the above

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