Waste Water Engineering Interview Questions and Answers - Set 18 - ObjectiveBooks

Waste Water Engineering Interview Questions and Answers - Set 18

Practice Test: Question Set - 18


1. Disposal to sewage in large cities, is done in
    (A) Irrigation
    (B) Dilution
    (C) Oxidation
    (D) Purification

2. 3.0 ml of raw sewage is diluted to 300 ml. The D.O. concentration of the diluted sample at the beginning of the test was 8 mg/l. After 5 day-incubation at 20°C, the D.O. concentration was 5 mg/l. The BOD of raw sewerage is
    (A) 100 mg/l
    (B) 200 mg/l
    (C) 300 mg/l
    (D) 400 mg/l

3. The digested sludge from septic tanks, is removed after a maximum period of
    (A) 3 years
    (B) 3.5 years
    (C) 4 years
    (D) 5 years

4. Assertion (A): The minimum self cleansing velocity in the sewer, at least once a day, must be generated.
Reason (R): If certain deposition takes place and is not removed, it obstructs free flow and causes further deposition leading to complete blocking of the sewer.
    (A) Both A and R are true and R is the correct explanation of A
    (B) Both A and R are 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

5. The presence of free ammonia in sewage, is detected by
    (A) Boiling
    (B) Adding potassium permanganate
    (C) Adding sulphuric acid
    (D) Phenol-di-sulphuric acid

6. Dry water flow in a combined sewer, is
    (A) Industrial sewage
    (B) Domestic sewage
    (C) Storm water
    (D) Inclusive of domestic and industrial sewage but excludes storm water

7. The porosity of sediments in sewer pipes, is usually taken as
    (A) 0.010
    (B) 0.011
    (C) 0.012
    (D) 0.013

8. In sewage having fully oxidized organic matter, the nitrogen exists in the form of
    (A) Nitrites
    (B) Nitrates
    (C) Free ammonia
    (D) Aluminoid nitrogen

9. The minimum diameter of sewer to be adopted is
    (A) 10 cm
    (B) 12.5 cm
    (C) 15 cm
    (D) 25 cm

10. If the diameter of sewer is 225 mm, the gradient required for generating self cleansing velocity, is
    (A) 1 in 60
    (B) 1 in 100
    (C) 1 in 120
    (D) None of these

11. The sewerage system consists of
    (A) House sewer
    (B) Lateral sewer
    (C) Branch sewer
    (D) All of these

12. Clogging of sewers, is caused due to
    (A) Silting
    (B) Low discharge
    (C) Greasy and oily matters
    (D) All the above

13. Oxidation process results in the formation of
    (A) Carbon dioxide
    (B) Nitrates
    (C) Sulphates
    (D) All the above

14. The sewage is pumped up
    (A) From low lying areas
    (B) From flat areas
    (C) From basements
    (D) All the above

15. The angle subtended by the surface of sewer water with partial flow, at sewer centre is 120°, the depth of sewerage is
    (A) 20 cm
    (B) 25 cm
    (C) 40 cm
    (D) 50 cm

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