A. 4-8 hours
B. 24 hours
C. 10 to 15 days
D. 3 months
Related Mcqs:
- The detention period in coagulation tanks is usually kept as_______________?
A. 1 to 2 minutes
B. 30 to 45 minutes
C. 2 to 6 hours
D. 2 to 6 days - Generally the detention period for grit chambers is kept as_______________?
A. 1 minute
B. 5 minutes
C. 2-4 hours
D. 12 hours - The detention period and overflow rate respectively for plain sedimentation as compared to sedimentation with coagulation are generally_______________?
A. less and more
B. less and less
C. more and less
D. more and more - The hourly variation factor is usually taken as______________?
A. 1.5
B. 1.8
C. 2.0
D. 2.7 - The main disadvantage of oxidation pond is that________________?
A. large area is required for construction
B. maintenance and operation cost are high
C. BOD removal is very low
D. none of the above - Laying of sewers is usually done with the help of________________?
A. a theodolite
B. a compass
C. sight rails and boning rods
D. a plane table - Sewerage system is usually designed for_________________?
A. 10 years
B. 25 years
C. 50 years
D. 75 years - Ground water is usually free from________________?
A. suspended impurities
B. dissolved impurities
C. both suspended and dissolved impuri¬ties
D. none of the above - As compared to higher pH values, the contact period required for efficient chlorination at lower pH values is___________________?
A. smaller
B. larger
C. same
D. none of the above - Period of cleaning of slow sand filters is about________________?
A. 24 – 48 hours
B. 10-12 days
C. 2-3 months
D. 1-2 year
