A. 1 in 5
B. 1 in 10
C. 1 in 15
D. 1 in 20
Related Mcqs:
- 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 - The sewage treatment in septic tanks is due to__________________?
A. Anaerobic decomposition
B. Aerobic decomposition
C. Parasitic decomposition
D. None of these - 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 - The digested sludge from septic tanks, is removed after a maximum period of__________________?
A. 3 years
B. 3.5 years
C. 4 years
D. 5 years - 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 - 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 - 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 - In a grit chamber of a sewage treatment plant ____________________?
A. Flow velocity 0.15 m to 0.3 m/sec is kept
B. Depth of 0.9 m to 1.20 m is kept
C. One minute of detention period is kept
D. All the above - A cylindrical ejector having its height 2 m fills after every 10 minutes with a peak sewage discharge of 0.0157 cumec. The diameter of the ejector chamber, is_____________________?
A. 2.30 m
B. 2.40 m
C. 2.45 m
D. 2.50 m - 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_________________?
A. 0.50 m/sec
B. 0.60 m/sec
C. 0.70 m/sec
D. 0.75 m/sec