148. The sewage discharge in a detritus tank of a treatment plant is 576 litres/sec with flow velocity of 0.2 m/sec. If the ratio of width to depth is 2, the depth is
A. 100 cm
B. 110 cm
C. 120 cm
D. 150 cm.
149. In primary sedimentation, the 0.2 mm inorganic solids get separated if specific gravity is
A.2.25
B.2.5
C.2.55
D.2.65
150. The settlement of a particle in sedimentation tank, is affected by
A. velocity of flow
B. viscosity of water
C. size and shape of solid
D. all the above.
151. Discrete or granular particles change their
A. size
B. shape
C. weight
D. none of these.
152. Flocculated particles do not change their
A. size
B. shape
C. weight
D. none of these.
153. The settling velocity of a spherical particle of diameter less than 0.1 mm as per Stock's law, is
A. V, = 418 (G, - G,?)d[100
B. V = 418 (G, - G?.,)d2[ 371070
C. V, = 218 (G, - Gidd2 [ 3T1t107?
D. V, = 218 (G, - Gi?)d[ 3T +
154. Hazin's formula= 418 (G, -3T+ 7? is used for the settlement 100 velocity of the particles of diameter
A. less than 0.01 mm
B. less than 0.05 mm
C. less than 0.1 mm
D. greater than 0 1 mm.
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