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

Related Mcqs:

1. 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

2. 5 days-biochemical oxygen demand (BOD5) is taken at a temperature of_________________?

   A. 0°C
   B. 15°C
   C. 20°C
   D. 25°C

3. To test chemical oxygen demand (C.O.D.) of sewage, organic matter is oxidised by potassium dichromate in the presence of_______________?

   A. Hydrochloric acid
   B. Sulphuric acid
   C. Nitric acid
   D. Citric acid

4. 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

5. 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

6. 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

7. 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

8. Clogging of sewers, is caused due to_______________?

   A. Silting
   B. Low discharge
   C. Greasy and oily matters
   D. All the above

9. Dilution method of disposing of sewage, is not preferred to_______________?

   A. When sewage is fresh
   B. When diluting water has high dissolved oxygen content
   C. When diluting water is used for water supply near the point of sewage disposed
   D. When the diluting water is having flow currents

10. The amount of oxygen consumed by the aerobic bacterias which cause the aerobic biological decomposition of sewage, is known_________________?

    A. Bio-Chemical Oxygen Demand (B.O.D.)
    B. Dissolved Oxygen (D.O.)
    C. Chemical Oxygen Demand (C.O.D.)
    D. None of these