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