Questions Answers Waste Water Engineering - Set 15 - ObjectiveBooks

# Practice Test: Question Set - 15

1. Ventilating shafts are provided to a sewer line at every
(A) 100 m
(B) 150 m
(C) 200 m
(D) 300 m

2. Boussinesq's equation for ascertaining unit pressure at a depth ‘H’ on sewers due to traffic loads, is
(A) pt = 3H3p/2Ï€Z5
(B) pt = 2H3p/3Ï€Z5
(C) pt = 3H3p/2Z5
(D) pt = 2Ï€H3p/3Z5

3. The most efficient cross section of sewers in a separate sewerage system is
(A) Parabolic
(B) Circular
(C) Rectangular
(D) New egged

4. If the over land flow from the critical point to the drain is 8 km and the difference in level is 12.4 m, the inlet time is
(A) 2 hours
(B) 3 hours
(C) 4 hours
(D) 5 hours

5. For trunk sewers more than 1.25 m in diameter, the ratio of the maximum daily sewage flow to the average daily sewage flow is assumed
(A) 1.5
(B) 2.0
(C) 2.5
(D) 3.0

6. The settlement of a particle in sedimentation tank, is affected by
(A) Velocity of flow
(B) Viscosity of water
(C) Size and shape of solid
(D) All the above

7. If the pH value of sewage is 7
(A) It is acidic
(B) It is alkaline
(C) It is neutral
(D) None of these

8. A sewer pipe contains 1 mm sand particles of specific gravity 2.65 and 5 mm organic particles of specific gravity 1.2, the minimum velocity required for removing the sewerage, is
(A) 0.30 m/sec
(B) 0.35 m/sec
(C) 0.40 m/sec
(D) 0.45 m/sec

9. The width of a settling tank with 2 hour detention period for treating sewage 378 cu m per hour, is
(A) 5 m
(B) 5.5 m
(C) 6.5 m
(D) 7 m

10. The sewer which collects the discharge from a collecting system and delivers it to a treatment plant, is known
(A) House sewer
(B) Lateral sewer
(C) Branch sewer
(D) Sewer outfall

11. For non-scouring velocity 5 m/sec, the type of sewers generally preferred to, is
(A) Cast iron sewers
(B) Cement concrete sewers
(C) Glazed bricks sewers
(D) Stone ware sewers

12. Pick up the correct statement from the following:
(A) The boning rod is used for checking the levels of the sewer inverts
(B) Manhole covers are made circular for the convenience of the cleaning staff
(C) A manhole is classified as shallow manhole if its depth is less than 0.9 m
(D) All the above

13. The ratio of maximum sewage flow to average sewage flow for trunk mains having diameters more than 1.25 m, is
(A) 1.5
(B) 2.0
(C) 3.0
(D) 4.0

14. The most dangerous pollutant in vehicular emissions is
(A) CO
(B) SO2
(C) CO2
(D) O3

15. Large diameter sewers subjected to external pressure alone, are reinforced
(A) Near the inner surface of the pipe
(B) Near the outer surface of the pipe
(C) Both (a) and (b)
(D) With elliptical cage

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