Waste Water Engineering

111. In 1000 kg of sewage, the total solids approximate

1. 0.5 to 1.0 kg
2. 1 kg to 2.0 kg
3. 5 kg to 7.5 kg
4. 7.5 kg to 10 kg

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112. In a city the ratio of the drainage to sewage is 20, the percentage discharge passing through nonmonsoon periods, is

1. 5
2. 10
3. 15
4. 20

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113. In a fully mechanised composting plant, involves

1. Mechanized receipt
2. Mechanized segregation
3. Mechanized pulverising of refuse
4. All of these

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114. In a grit chamber of a sewage treatment plant,

1. Flow velocity 0.15 m to 0.3 m/sec is kept
2. Depth of 0.9 m to 1.20 m is kept
3. One minute of detention period is kept
4. All the above

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115. In a residential colony, sewers of diameters 100 mm, 150 mm and 225 mm were laid with a gradient 1 in 120. Which portion of the sewage system does not choke in due course of time?

1. 100 mm dia.
2. 150 mm dia.
3. 225 mm dia.
4. All of these

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116. In a sedimentation tank (length L, width B, depth D) the settling velocity of a particle for a discharge Q, is

1. Q/(B × D)
2. Q/(L × D)
3. Q/L
4. Q/(B × L)

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117. In a sludge digestion tank if the moisture content of sludge V1 litres is reduced from p₁ % to p₂ % the volume V₂ is

1. [(100 + P₁)/(100 - P₂)] V₁
2. [(100 - P₁)/(100 + P₂)] V₁
3. [(100 - P₁)/(100 - P₂)] V₁
4. [(100 + P₂)/(100 - P₁)] V₁

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118. In a sludge tank, the gas mainly produced, is

1. Oxygen
2. Nitrogen
3. Hydrogen
4. Carbon dioxide

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119. In a trickling filter

1. Filtration process is used
2. Biological action is used
3. Neither (a) nor (b)
4. Both (a) and (b)

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120. In areas where light rains are uniformly distributed throughout the year, the type of sewerage system to be adopted is

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

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