Waste Water Treatment Objective Questions - Set 10 - ObjectiveBooks

Waste Water Treatment Objective Questions - Set 10

Practice Test: Question Set - 10

1. Antisyphonage pipe is fitted
    (A) At the end of septic tanks
    (B) On manholes
    (C) With a W.C. trap
    (D) At the beginning of sewer line

2. In a grit chamber of a sewage treatment plant,
    (A) Flow velocity 0.15 m to 0.3 m/sec is kept
    (B) Depth of 0.9 m to 1.20 m is kept
    (C) One minute of detention period is kept
    (D) All the above

3. The ratio of maximum sewage flow to average sewage flow for mains up to 1 m in diameter, is
    (A) 1.5
    (B) 2.0
    (C) 3.0
    (D) 4.0

4. pH value of sludge during alkaline regression stage, is
    (A) More than 7
    (B) Less than 7
    (C) Less than 6
    (D) More than 6

5. The arrangement made for passing the sewer line below an obstruction below the hydraulic gradient lines called
    (A) Inverted syphon
    (B) Depressed sewer
    (C) Sag pipe
    (D) All of these

6. Pick up the incorrect size of stone ware sewers
    (A) 52.5 cm
    (B) 67.5 cm
    (C) 82.5 cm
    (D) None of these

7. Chlorination of water is done for the removal of
    (A) Bacterias
    (B) Suspended solids
    (C) Sediments
    (D) Hardness

8. Sludge banks are formed if sewage is disposed of in
    (A) Rivers
    (B) Seas
    (C) Lakes
    (D) None of these

9. Assertion (A): A free board of 0.3 m is provided above the top sewage line in septic tanks.
Reason (R): It helps to accommodate the scum in the septic tank.
    (A) Both A and R is true and R is the correct explanation of A
    (B) Both A and R is true but R is not a correct explanation of A
    (C) A is true but R is false
    (D) A is false but R is true

10. The temperature affects the
    (A) Biological activity of bacteria in sewage
    (B) Solubility of gases in sewage
    (C) Viscosity of sewage
    (D) All the above

11. The clarigesters are
    (A) Circular septic tanks
    (B) Rectangular septic tanks
    (C) Circular Imhoff double tanks with bottom hoppers
    (D) Circular Imhoff double storey tanks without bottom hoppers

12. The density of population over 40 hectares is 250/hectare. If water supply demand per day is 200 liters and sewage discharge is 80% of water supply, the sewage flow in sewers of separate system, is
    (A) 0.05552 cumec
    (B) 0.05554 cumec
    (C) 0.05556 cumec
    (D) 0.0556 cumec

13. In a residential colony, sewers of diameters 100 mm, 150 mm and 225 mm were laid with a gradient 1 in 120. Which portion of the sewage system does not choke in due course of time?
    (A) 100 mm dia.
    (B) 150 mm dia.
    (C) 225 mm dia.
    (D) All of these

14. The spacing of bars for perforations in coarse screens used for the treatment of sewage, is
    (A) 20 mm
    (B) 30 mm
    (C) 40 mm
    (D) 50 mm

15. In case of Imhoff tanks,
    (A) The shape is rectangular
    (B) Detention period is 2 hours
    (C) The velocity of flow is restricted to 0.30 m/minute
    (D) All the above

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