The maximum efficiency of BOD removal is achieved in______________?

Related Mcqs:

1. In a BOD test, 1.0 ml of raw sewage was diluted to 100 ml and the dissolved oxygen concentration of diluted sample at the beginning was 6 ppm and it was 4 ppm at the end of 5 day incubation at 20°C. The BOD of raw sewage will be___________?

   A. 100 ppm
   B. 200 ppm
   C. 300 ppm
   D. 400 ppm

2. The ratio of 5 day BOD to ultimate BOD is about_______________?

   A. 1/3
   B. 2/3
   C. 3/4
   D. 1.0

3. If Biochemical oxygen demand (BOD. of a town is 20000 kg/day and BOD per capita per day is 0.05 kg, then population equivalent of town is_________________?

   A. 1000
   B. 4000
   C. 100000
   D. 400000

4. Standard BOD is measured at________________?

   A. 20°C – 1day
   B. 25°C- 3day
   C. 20°C – 5day
   D. 30°C- 5day

5. The rate of BOD exerted at any time is_____________?

   A. directly proportional to BOD satisfied
   B. directly proportional to BOD remain-ing
   C. inversely proportional to BOD satisfied
   D. inversely proportional to BOD re-maining

6. The relative stability of a sewage sample, whose dissolved oxygen is same as the total oxygen required to satisfy BOD, is______________?

   A. 1
   B. 100
   C. infinite
   D. zero

7. The correct relation between theoretical oxygen demand (TOD), Biochemical oxygen demand (BOD) and Chemical oxygen demand (COD) is given by_______________?

   A. TOD>BOD>COD
   B. TOD>COD>BOD
   C. BOD>COD>TOD
   D. COD>BOD>TOD

8. Assertion A: Slow sand filters are more efficient in removal of bacteria than rapid sand filters. Reason R : The sand used in slow sand filters is finer than that in rapid sand filters. Select your answer based on the coding system given below?

   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 the correct explanation of A
   C. A is true but R is false
   D. A is false but R is true

9. Disinfection of water results in______________?

   A. removal of turbidity
   B. removal of hardness
   C. killing of disease bacteria
   D. complete sterilisation

10. For a given discharge, the efficiency of sedimentation tank can be increased by______________?

    A. increasing the depth of tank
    B. decreasing the depth of tank
    C. increasing the surface area of tank
    D. decreasing the surface area of tank