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.Management Sciences
Category: Environmental Engineering
Corrosion in concrete sewers is caused by______________?
A. septic conditions
B. dissolved oxygen
C. chlorine
D. nitrogen
As compared to rapid sand filters, slow sand filters give______________?
1) slower filtration rate
2) higher filtration rate
3) lesser efficiency in removal of bacteria
4) higher efficiency in removal of bacteria
The correct answer is?
A. (1) and (2)
B. (2) and (3)
C. (1) and (4)
D. (2) and (4)
The velocity of flow of water in a sedimentation tank is about__________________?
A. 5 to 10 cm/sec.
B. 15 to 30 cm/sec.
C. 15 to 30 cm/minute
D. 15 to 30 cm/hour
The suitable layout of distribution system for a city with roads of rectangular pattern is______________?
A. grid iron system
B. dead end system
C. ring system
D. radial system
The percentage of filtered water, which is used for backwashing in rapid sand filters, is about______________?
A. 0.2 to 0.4
B. 0.4 to 1.0
C. 2 to 4
D. 5 to 7
The rate of Alteration of pressure filters is_________________?
A. less than that of slow sand filters
B. in between the filtration rate of slow sand filters and rapid sand filters
C. greater than that of rapid sand filters
D. equal to that of slow sand filters
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
A pipe conveying sewage from plumbing system of a single building to common sewer or point of immediate disposal is called________________?
A. house sewer
B. lateral sewer
C. main sewer
D. submain sewer
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
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