MCQ
16261. The percentage of chlorine in fresh bleaching powder is-
20 to 25%
25 to 30%
30 to 35%
35 to 40%
16262. The minimum diameter of a manhole cover should be-
25cm
50cm
75cm
100cm
16263. The biochemical treatment of sewage effluent is a process of-
oxidation
self-purification
deoxidation
sedimentation
16264. The aeration of water is done to remove--
colour
taste
odour
all of these
16265. The process of killing pathogenic bacterias from water is called-
sedimentation
coagulation
filteration
disinfection
16266. The equipment used for cleaning the sewers easily is called-
gauge
claw
scoop
scraper
16267. The minimum size of a fire hydrant is--
5cm
10cm
15cm
20cm
16268. In primary settling tank, suspended solids are reduced from-
10 to 20%
20 to 40%
40 to 70%
70 to 90%
16269. The water from kitchens, bathrooms, wash basins is called-
sewage
raw sewage
sullage
none of this
16270. In high rate activated sludge treatment, bacteria are removed from-
20 to 40%
40 to 60%
60 to 80%
80 to 95%
16271. The time of contact for chlorination should be at least-
5 minutes
20 minutes
1 hour
2 hours
16272. Rapid sand filter can remove turbidity from water upto an extent of-
15 to 25 ppm
25 to 35 ppm
35 to 40 ppm
40 to 50 ppm
16273. The amount of chlorine used for plain b chlorination of water is about-
0.2 ppm
0.3 ppm
0.4 ppm
0.5 ppm
16274. The secondary treatment of sewage is carried out by the use of-
screens
grit chambers
trickling filters
chlorinators
16275. The cross-section recommended for separate system of sewerage is--
circular
rectangular
egg-shaped
none of these
16276. Grit chambers of a sewage plant are usually changed after-
1 day
2 weeks
1 week
4 weeks
16277. The effluents from the septic tank are discharged into--
soak pit
drainage
oxidation pond
sewer
16278. By lime soda process, hardness can be reduced to less than
50 ppm
75 ppm
150 ppm
100 ppm
16279. The human excreta is a ---waste.
dry
liquid
semi-liquid
solid
16280. The internal diameter of the sewer should not be less than-
15cm
25cm
50cm
75cm