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
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 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 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 - 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 - The sewage treatment in septic tanks is due to__________________?
A. Anaerobic decomposition
B. Aerobic decomposition
C. Parasitic decomposition
D. None of these - The effluent of a septic tank is_________________?
A. Fit for discharge into any open drain
B. Foul and contains dissolved and suspended solids
C. As good as that from a complete treatment
D. None of these - In septic tanks__________________?
A. Free board of 0.3 m may be provided
B. The baffles or tees are extended up to top level of scum
C. The clear space between the baffle top and covering slab is about 7.5 cm
D. All the above - Skimming tanks are__________________?
A. Used to remove the grease and oil
B. Those from which sludge is skimmed out
C. Tanks provided with self- cleansing screens
D. Improved version of grit chambers - The normal values of over flow rates for secondary sedimentation tanks, ranges between__________________?
A. 25,000 to 35,000 litres/sqm/day
B. 40,000 to 50,000 litres/sqm/day
C. 50,000 to 60,000 litres/sqm/day
D. 80,000 to 10,000 litres/sqm/day
