Waste Water Engineering

161. Primary treatment of sewage consists of removal of

1. Large suspended organic solids
2. Oil and grease
3. Sand and girt
4. Floating materials

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162. R.M.O. expenses include

1. Running expenses
2. Maintenance expenses
3. Operation expenses
4. All the above

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163. Rate of flow of sewage is generally assumed

1. More than the rate of water supply
2. Equal to the rate of water supply
3. Less than the rate of water supply
4. At 150 litres per capita

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164. Removal of oil and grease from sewage, is known

1. Screening
2. Skimming
3. Filtration
4. None of these

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165. Self-cleansing velocity is

1. Velocity at dry weather flow
2. Velocity of water at flushing
3. Velocity at which no accumulation remains in the drains
4. Velocity of water in a pressure filter

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166. Setting out the alignments of sewers may start from

1. City
2. Out-fall
3. Tail end
4. Any point

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167. Sewer manholes are generally provided at

1. The change of gradient
2. The change of direction
3. The junctions of sewers
4. All of these

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168. Sewer pipes are designed for maximum discharge with 25% to 33% vacant cross-sectional area for

1. Unexpected large scale infiltration of stream water
2. Unexpected increase in the population
3. Under estimates of maximum and average flows
4. All of the above

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169. Sewer pipes need be checked for

1. Minimum flow
2. Maximum flow
3. Both (a) and (b)
4. None of these

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170. Sewer ventilating columns are generally placed at

1. Distances 150 m to 300 m
2. Upper ends of branch sewers
3. Every change in the size of sewers
4. All the above

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