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