Waste Water Engineering problems
- 1. A nuisance is experienced in diluting water if dilution factor is less than
Options- A. 100
- B. 60
- C. 40
- D. 20
- E. 10 Discuss
Correct Answer: 20
- 2. Drop manholes at the junctions of sewer lines, are provided if
Options- 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. Discuss
Correct Answer: invert level of a branch sewer is more than 60 cm that of the main sewer
- 3. In sewage, the solids in mg per litre is
Options- A. 100 to 500
- B. 500 to 1000
- C. 1000 to 1500
- D. 1500 to 2000 Discuss
Correct Answer: 500 to 1000
- 4. In case of sewer lines
Options- A. water test is carried out to check water tightness of the joints
- B. test for straightness is carried out with the help of a lamp and mirror
- C. obstruction test is carried out with the. help of smooth ball of diameter 13 mm
- D. all the above. Discuss
Correct Answer: all the above.
- 5. 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.
Options- 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. Discuss
Correct Answer: Both A and R are true and R is the correct explanation of A
- 6. 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 DO. concentration was 5 mg/l. The BOD of raw sewerage is
Options- A. 100 mg/l
- B. 200 mg/l
- C. 300 mg/l
- D. 400 mg/l. Discuss
Correct Answer: 300 mg/l
- 7. The arrangement made for passing the sewer line below an obstruction below the hydraulic gradient lines called
Options- A. inverted syphon
- B. depressed sewer
- C. sag pipe
- D. all of these. Discuss
Correct Answer: all of these.
- 8. If a paper moistened with lead acetate for five minutes when placed in manhole turns black. The sewer certainly contains
Options- A. Hydrogen sulphide
- B. Carbon dioxide
- C. Methane
- D. Oxygen
- E. None of these. Discuss
Correct Answer: Hydrogen sulphide
- 9. A safety lamp when inserted in the upper portion of a manhole causes flames. It indicates the presence of
Options- A. Carbondioxide gas
- B. Hydrogen sulphide gas
- C. Methane gas
- D. Petrol vapours. Discuss
Correct Answer: Methane gas
- 10. To test chemical oxygen demand (C.O.D.) of sewage, organic matter is oxidised by pottassium dichromate in the presence of
Options- A. Hydrochloric acid
- B. Sulphuric acid
- C. Nitric acid
- D. Citric acid. Discuss
Correct Answer: Sulphuric acid
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