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_________________?

Related Mcqs:

1. If 2% solution of a sewage sample is incubated for 5 days at 20°C and depletion of oxygen was found to be 5 ppm, B.O.D. of the sewage is____________________?

   A. 200 ppm
   B. 225 ppm
   C. 250 ppm
   D. None of these

2. If the depletion of oxygen is found to be 5 ppm after incubating a 2.5% solution of sewage sample for 5 days at 21°C, B.O.D. of the sewage is_____________________?

   A. 50 ppm
   B. 100 ppm
   C. 150 ppm
   D. 200 ppm

3. 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

4. 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

5. Bio-chemical oxygen demand (BOD) for the first 20 days in generally referred to_______________?

   A. Initial demand
   B. First stage demand
   C. Carbonaceous demand
   D. All of these

6. For the survival of fish in a river stream, the minimum dissolved oxygen is prescribed________________?

   A. 3 ppm
   B. 4 ppm
   C. 5 ppm
   D. 10 ppm

7. Which of the following pumps in used to pump sewage solids with liquid sewage without clogging the pump is ?

   A. Centrifugal pump
   B. Pneumatic ejector
   C. Reciprocating pump
   D. None of these

8. The density of population over 40 hectares is 250/hectare. If water supply demand per day is 200 litres 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

9. For trunk sewers more than 1.25 m in diameter, the ratio of the maximum daily sewage flow to the average daily sewage flow is assumed________________?

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

10. 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