The digested sludge from septic tanks, is removed after a maximum period of__________________?

Related Mcqs:

1. Assertion A.: A free board of 0.3 m is provided above the top sewage line in septic tanks. Reason (R): It helps to accommodate the scum in the septic tank_________________?

   A. Both A and R is true and R is the correct explanation of A
   B. Both A and R is 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

2. The moisture content of sludge is reduced from 90% to 80% in a sludge digestion tank. The percentage decrease in the volume of sludge, is_______________?

   A. 25 %
   B. 50 %
   C. 10 %
   D. 5 %

3. The rate of accumulation of sludge in septic tanks is recommended as____________________?

   A. 30 litres/person/year
   B. 25 litres/person/year
   C. 30 litres/person/month
   D. 25 litres/person/month

4. In a sludge digestion tank if the moisture content of sludge V1 litres is reduced from p1 % to p2 % the volume V2 is____________________?

   A. [(100 + P1)/(100 – P2)] V1
   B. [(100 – P1)/(100 + P2)] V1
   C. [(100 – P1)/(100 – P2)] V1
   D. [(100 + P2)/(100 – P1)] V1

5. The bottom of the sewage inlet chamber of septic tanks, is provided an outward slope_________________?

   A. 1 in 5
   B. 1 in 10
   C. 1 in 15
   D. 1 in 20

6. In septic tanks, decomposition of organic bacteria, is done by_____________________?

   A. Anaerobic bacteria
   B. Aerobic bacteria
   C. Both types of bacterias
   D. None of these

7. The sewage treatment in septic tanks is due to__________________?

   A. Anaerobic decomposition
   B. Aerobic decomposition
   C. Parasitic decomposition
   D. None of these

8. Which one of the following statements regarding septic tanks is wrong ?

   A. A gap of 7.5 cm between the bottom of the covering slab and the top level of scum is provided
   B. The outlet invert level is kept 5 to 7.5 cm below the inlet invert level
   C. The minimum width of septic level is 90 cm
   D. The depth of tank is kept equal to its width

9. Acid regression stage of sludge digestion at a temperature 21°C extends over a period of______________?

   A. 15 days
   B. 30 days
   C. 60 days
   D. 90 days

10. In normal conditions, the period for sludge digestion, is_______________?

    A. 10 days
    B. 20 days
    C. 30 days
    D. 60 days