The gas from sludge digestion tank is mainly composed of __________________?
(A) nitrogen
(B) carbon dioxide
(C) hydrogen sulphide
(D) methane
Settling velocity increases with_______________?
(A) specific gravity of solid particles
(B) size of particles
(C) depth of tank
(D) temperature of liquid
The correct relation between theoretical oxygen demand (TOD), Biochemical oxygen demand (BOD) and Chemical oxygen demand (COD) is given by_______________?
(A) TOD>BOD>COD
(B) TOD>COD>BOD
(C) BOD>COD>TOD
(D) COD>BOD>TOD
The minimum dissolved oxygen which should always be present in water in order to save the aquatic life is______________?
(A) 1 ppm
(B) 4 ppm
(C) 10 ppm
(D) 40 ppm
Dissolved oxygen in streams is______________?
(A) maximum at noon
(B) minimum at noon
(C) maximum at midnight
(D) same throughout the day
The means of access for inspection and cleaning of sewer line is known as_______________?
(A) inlet
(B) manhole
(C) drop manhole
(D) catch basin
Sewage treatment units are designed for_______________?
(A) maximum flow only
(B) minimum flow only
(C) average flow only
(D) maximum and minimum flow
Corrosion in concrete sewers is caused by______________?
(A) septic conditions
(B) dissolved oxygen
(C) chlorine
(D) nitrogen
Generally the detention period for grit chambers is kept as_______________?
(A) 1 minute
(B) 5 minutes
(C) 2-4 hours
(D) 12 hours