288. A five day B.O.D. at 15?C of the sewage of a town is 100 kg/day. If the 5 day B.O.D. per head at 15?C for standard sewage is 0.1 kg/day, the population equivalent is
A.100
B.1000
C.5000
D.10000
289. Disposal to sewage in large cities, is done in
A. irrigation
B. dilution
C. oxidation
D. putrifaction.
290. A nuisance is experienced in diluting water if dilution factor is less than
A.100
B.60
C.40
D.20
291. The sewage in oxidation ponds, is treated by
A. aerobic bacteria action
B. sedimentation
C. action of algae
D. both A and (c).
292. In a trickling filter
A. filtration process is used
B. biological action is used
C. neither A nor B
D. both A and B.
293. In trickling filter, B.O.D. is reduced to
A. 30 to 40%
B. 40 to 60%
C. 60 to 80%
D. 80 to 90%
294. In normal conditions, the period for sludge digestion, is
A. 10 days
B. 20 days
C. 30 days
D. 60 days
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