To prevent settling down of sewage both at the bottom and on the sides of a large sewer, self-cleaning velocity recommended for Indian conditions, is_________________?

Related Mcqs:

1. The settling velocity of the particles larger than 0.06 mm in a settling tank of depth 2.4 is 0.33 m per sec. The detention period recommended for the tank, is____________________?

   A. 30 minutes
   B. 1 hour
   C. 1 hour and 30 minutes
   D. 2 hours

2. 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

3. The dimensions of a rectangular settling tank are: length 24 m, width 6 m and depth 3 m. If 2 hour detention period for tanks is recommended, the rate of flow of sewage per hour, is_____________________?

   A. 204 cu.m
   B. 208 cu.m
   C. 212 cu.m
   D. 216 cu.m

4. For sewer mains of 0.5 to 1 m diameter, the ratio of maximum daily sewage flow to the average daily sewage flow is assumed__________________?

   A. 1.5
   B. 2.0
   C. 2.5
   D. 3.0

5. If the diameter of a sewer is 100 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

6. 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

7. If the diameter of a sewer is 150 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

8. If a 2% solution of sewage sample is incubated for 5 days at 20°C and the dissolved oxygen depletion was found to be 8 mg/l. The BOD of the sewage is_________________?

   A. 100 mg/l
   B. 200 mg/l
   C. 300 mg/l
   D. 400 mg/l

9. If the depletion of oxygen is found to be 2.5 mg/litre after incubating 2.5 ml of sewage diluted to 250 ml for 5 days at 20°C, B.O.D. of the sewage is_________________?

   A. 50 mg/l
   B. 100 mg/l
   C. 150 mg/l
   D. 250 mg/l

10. 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