Multiple Choice Questions on Waste Water Engineering - Set 03 - ObjectiveBooks

# Practice Test: Question Set - 03

1. 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

2. During preliminary treatment of a sewage
(A) Oil and grease are removed from skimming tanks
(B) Floating materials are removed by screening
(C) Girt and sand are removed by girt chambers
(D) All the above

3. 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

4. Dry weather flow is:
(A) Average daily rate of flow
(B) Average monthly rate of flow
(C) Average annual rate of flow
(D) Water supply allowance per capita

5. Pick up the incorrect statement from the following:
(A) The mixture of water and waste products, is called sewage
(B) The treated sewage effluents, are generally used for irrigating the crops
(C) The process of collecting, treating and disposing off the sewage, is called sewerage
(D) The old convergence system was definitely better than water carried sewerage system

6. Pick up the correct statement from the following:
(A) The maximum rate of storm runoff is called peak drainage discharge
(B) Rational method of estimating peak run off, may be used precisely for areas less than 50 hectares
(C) The period after which the entire area starts contributing to the runoff, is called the time of concentration
(D) All the above

7. If q is the average sewage flow from a city of population P, the maximum sewage flow
(A) Q = [(4 + √P)/(18 + √P)] q
(B) Q = [(18 + P)/(4 + √P)] q
(C) Q = [(18 + √P)/(4 + √P)] q
(D) Q = [(5 + √P)/((15 + √P)] q

8. ¾th or ¼th extra space is left in sewer pipes at maximum discharge for
(A) Low estimates of the average and maximum flows
(B) Large scale infiltration of storm water
(C) Unexpected increase in population
(D) All the above

9. 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

(B) Difference in heads between two points in circular pipes
(C) Mean of radii in a pipe line of varying cross-sections
(D) Cross-sectional area/wetted perimeter

11. If the depth of flow in a circular sewer is 1/4th of its diameter D, the wetted perimeter is
(A) Ï€D/2
(B) Ï€D/4
(C) Ï€D/3
(D) Ï€D

12. Pick up the correct statement from the following:
(A) Anaerobic bacteria flourish in the absence of oxygen
(B) Aerobic bacteria flourish in the presence of oxygen
(C) Facultative bacteria flourish with or without oxygen
(D) All the above

13. The Brake Horse power of the motor (efficiency 60%) required for a pump of capacity 0.075 cumec for a total lift of 12 m, is
(A) 10
(B) 15
(C) 20
(D) 25

14. Aerobic bacterias
(A) Flourish in the presence of free oxygen
(B) Consume organic matter as their food
(C) Oxidize organic matter in sewage
(D) All the above

15. 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

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