Waste Water Engineering

121. In areas where rainy season is limited to a few months, the type of sewerage system recommended is

1. Combined system
2. Partially separate system
3. Separate system
4. None of these

View answer

122. In case of Imhoff tanks,

1. The shape is rectangular
2. Detention period is 2 hours
3. The velocity of flow is restricted to 0.30 m/minute
4. All the above

View answer

123. In case of sewer lines

1. Water test is carried out to check water tightness of the joints
2. Test for straightness is carried out with the help of a lamp and mirror
3. Obstruction test is carried out with the help of smooth ball of diameter 13 mm
4. All the above

View answer

124. In Chezy's formula V = C√rs for calculating the velocity of flow in circular sewer of diameter 'D' running full, the value of hydraulic mean radius is

1. D
2. D/2
3. D/3
4. D/4

View answer

125. In circular sewers if depth of flow is 0.2 times the full depth, the nominal gradient,

1. Is only provided
2. Is doubled
3. Is trebled
4. Is not enough

View answer

126. In detritus tanks,

1. Flow velocity is kept 0.09 m/sec
2. Detention period is kept 3 to 4 minutes
3. Organic and inorganic materials are separated
4. All the above

View answer

127. In normal conditions, the period for sludge digestion, is

1. 10 days
2. 20 days
3. 30 days
4. 60 days

View answer

128. In olden days the type of section adopted in trunk and out fall sewers was

1. Parabolic shaped
2. Horse shoe shaped
3. Egg shaped
4. Circular shaped

View answer

129. In primary sedimentation, the 0.2 mm inorganic solids get separated if specific gravity is

1. 2.25
2. 2.5
3. 2.55
4. 2.65

View answer

130. In R.C. sewer pipes, the percentage longitudinal reinforcement to the cross-sectional area of concrete is kept

1. 10
2. 5
3. 2
4. 0.25

View answer