Waste Water Engineering Objective Questions and Answers - ObjectiveBooks

Waste Water Engineering Objective Questions and Answers

Practice Test: Question Set - 21


1. Fresh sewage may become stale in
    (A) One hour
    (B) Two to three hours
    (C) Three to four hours
    (D) Six hours

2. The small sewers are cleaned by
    (A) Flushing
    (B) Cane rodding
    (C) Wooden pills
    (D) None of these

3. The sewage discharge in a detritus tank of a treatment plant is 576 liters/sec with flow velocity of 0.2 m/sec. If the ratio of width to depth is 2, the depth is
    (A) 100 cm
    (B) 110 cm
    (C) 120 cm
    (D) 150 cm

4. If ‘D’ is the diameter of upper circular portion, the area of cross-section of a standard egg shaped sewer, is
    (A) [(18 + 5π)32]
    (B) [(12 + 5π)32]
    (C) [(18 + 5π)16]
    (D) [(82 + 5π)32]

5. Drop manholes at the junctions of sewer lines, are provided if
    (A) Invert level of a branch sewer is more than 60 cm that of the main sewer
    (B) Sewer line runs along a main road
    (C) Ordinary manhole cannot be built
    (D) Two sewer lines intersect

6. In sewage, the solids in mg per liter is
    (A) 100 to 500
    (B) 500 to 1000
    (C) 1000 to 1500
    (D) 1500 to 2000

7. During purification process of sewage the gas given off, is
    (A) Carbon dioxide
    (B) Hydrogen
    (C) Ammonia
    (D) All the above

8. The gas evolved in sewers is
    (A) Carbondioxide
    (B) Hydrogen sulphide
    (C) Methane
    (D) All of these

9. The sewerage system originates from
    (A) House sewers
    (B) Lateral sewers
    (C) Branch sewers
    (D) Main sewers

10. If a paper moistened with lead acetate for five minutes when placed in manhole turns black. The sewer certainly contains
    (A) Hydrogen sulphide
    (B) Carbon dioxide
    (C) Methane
    (D) Oxygen

11. In septic tanks, decomposition of organic bacteria, is done by
    (A) Anaerobic bacteria
    (B) Aerobic bacteria
    (C) Both types of bacterias
    (D) None of these

12. The sewer which transports the sewage to the point of treatment, is called
    (A) House sewer
    (B) Out-fall sewer
    (C) Branch sewer
    (D) Main sewer

13. Sewer pipes need be checked for
    (A) Minimum flow
    (B) Maximum flow
    (C) Both (a) and (b)
    (D) None of these

14. To test chemical oxygen demand (C.O.D.) of sewage, organic matter is oxidized by potassium dichromate in the presence of
    (A) Hydrochloric acid
    (B) Sulphuric acid
    (C) Nitric acid
    (D) Citric acid

15. ‘D’ is the diameter of a circular sewer and ‘α’ is the side of a square section sewer. If both are hydraulically equivalent, the relationship which holds good, is
    (A) πD8/3 = 4 b8/3
    (B) πD3/8 = 4 b3/8
    (C) πD2/3 = 4 b2/3
    (D) πD3/2 = 4 b3/2

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