MCQ
4021. The minimum diameter of a manhole cover should be-
25cm
50cm
75cm
100cm
4022. The water from kitchens, bathrooms, wash basins is called-
sewage
raw sewage
sullage
none of this
4023. The effluents from the septic tank are discharged into--
soak pit
drainage
oxidation pond
sewer
4024. The aeration of water is done to remove--
colour
taste
odour
all of these
4025. The secondary treatment of sewage is carried out by the use of-
screens
grit chambers
trickling filters
chlorinators
4026. The equipment used for cleaning the sewers easily is called-
gauge
claw
scoop
scraper
4027. The percentage of chlorine in fresh bleaching powder is-
20 to 25%
25 to 30%
30 to 35%
35 to 40%
4028. Biological action is used in-
screens
trickling filters
sedimentation tank
all of these
4029. The minimum size of a fire hydrant is--
5cm
10cm
15cm
20cm
4030. The cross-section recommended for separate system of sewerage is--
circular
rectangular
egg-shaped
none of these
4031. The internal diameter of the sewer should not be less than-
15cm
25cm
50cm
75cm
4032. By lime soda process, hardness can be reduced to less than
50 ppm
75 ppm
150 ppm
100 ppm
4033. Air vent pipe is not essentially required in a septic tank-
true
false
4034. Grit chambers of a sewage plant are usually changed after-
1 day
2 weeks
1 week
4 weeks
4035. The sewage is treated by aerobic bacteria action in -
settling tank
oxidation pond
trickling filter
all of these
4036. In primary settling tank, suspended solids are reduced from-
10 to 20%
20 to 40%
40 to 70%
70 to 90%
4037. Aerobic bacteria takes place in the of ---light.
Presence
absence
4038. The human excreta is a ---waste.
dry
liquid
semi-liquid
solid
4039. The biochemical treatment of sewage effluent is a process of-
oxidation
self-purification
deoxidation
sedimentation
4040. In high rate activated sludge treatment, bacteria are removed from-
20 to 40%
40 to 60%
60 to 80%
80 to 95%