Q.1

For sewer mains of 0.5 to 1 m diameter, the ratio of maximum daily sewage flow to the average daily sewage flow is assumed

  • 1.5
  • 2.0
  • 2.5
  • 3.0
Q.2

For design of sewers, percentage of sewage discharge is assumed

  • 65 to 70%
  • 70 to 75%
  • 75 to 80%
  • 85%.
Q.3

If a paper moistened with lead acetate for five minutes when placed in manhole turns black. The sewer certainly contains

  • Hydrogen sulphide
  • Carbon dioxide
  • Methane
  • Oxygen
  • None of these.
Q.4

5 days-biochemical oxygen demand (BOD5) is taken at a temperature of

  • 0°C
  • 15°C
  • 20°C
  • 25°C.
Q.5

Assertion (A) : The minimum self cleansing velocity in the sewer, at least once a day, must be generated.

Reason (R) : If certain deposition takes place and is not removed, it obstructs free flow and causes further deposition leading to complete blocking of the sewer.

  • Both A and R are true and R is the correct explanation of A
  • Both A and R are true but R is not a correct explanation of A
  • A is true but R is false
  • A is false but R is true.
Q.6

For sewer mains of 0.5 to 1 m diameter, the ratio of maximum daily sewage flow to the average daily sewage flow is assumed

  • 1.5
  • 2.0
  • 2.5
  • 3.0
Q.7

The detention time (t) of a settling tank, may be defined as the time required for

  • a particle to travel along its length
  • a particle to travel from top surface to bottom sludge zone
  • the flow of sewage to fill the tank
  • none of these.
Q.8

In sewage, the solids in mg per litre is

  • 100 to 500
  • 500 to 1000
  • 1000 to 1500
  • 1500 to 2000
Q.9

If D is the diameter of upper circular portion, the area of cross-section of a standard egg shaped sewer, is

Q.10

The water carried sewerage system removes

  • domestic sewage
  • industrial sewage
  • storm sewage
  • all the above.
Q.11

The moisture content of a sludge is reduced fromtoin a sludge digestion tank. The percentage decrease in the volume of sludge, is

  • 25%
  • 50%
  • 10%
  • 5%.
Q.12

Traps

  • are water seals which prevent the entry of foul gases
  • are used to trap the rats entering sewers
  • dissolve the foul gases
  • create syphonic action to increase the quick disposal of sewerage.
Q.13

In case of sewer lines

  • water test is carried out to check water tightness of the joints
  • test for straightness is carried out with the help of a lamp and mirror
  • obstruction test is carried out with the. help of smooth ball of diameter 13 mm
  • all the above.
Q.14

The design period of sewage treatment works in normally

  • 5 - 10 years
  • 15 - 20 years
  • 30 - 40 years
  • 40 - 50 years.
Q.15

Water content of sewage is about

  • 90%
  • 95%
  • 99.9%
  • 9.9%.
Q.16

Stoneware sewers are available in size

  • 10 cm
  • 15 cm
  • 20 cm
  • 25 cm
  • all the above.
Q.17

Inter-distance between ventilation columns in a sewer line is kept

  • 25 to 50 m
  • 50 m to 100 m
  • 100 m to 150 m
  • 150 m to 300 m.
Q.18

For estimating the peak run off the rational formula Q = 0.KpA was evolved by

  • Kinchling
  • Lloyd Davis
  • Frubling
  • all the above.
Q.19

The sewerage system originates from

  • house sewers
  • lateral sewers
  • branch sewers
  • main sewers
  • out fall sewers.
Q.20

The porosity of sediments in sewer pipes, is usually taken as

  • 0.010
  • 0.011
  • 0.012
  • 0.013
  • 0.020
Q.21

Imhoff cone is used to measure

  • total organic solids
  • total solids
  • total in organic solids
  • settleable solids.
Q.22

The sludge does not contain waste water from

  • bath rooms
  • wash basins
  • kitchen sinks
  • toilets.
Q.23

Pick up the correct statement from the following :

  • Inlets are provided on the road surface at the lowest point for draining rain water
  • Inlets are generally provided at an interval of 30 m to 60 m along straight roads
  • Inlets having vertical openings, are called curb inlets
  • Inlets having horizontal openings, are called horizontal inlets
  • All the above.
Q.24

For a grit chamber, if the recommended velocity of flow is 0.2 m/sec and detention period is 2 minutes, the length of the tank, is

  • 16 m
  • 20 m
  • 24 m
  • 30 m.
Q.25

The factor responsible for purification of sewage in river is

  • Hydrology
  • Dissolved oxygen in water
  • Temperature
  • Turbulence
  • All the above.
Q.26

Pick up the correct statement from the following :

  • The boning rod is used for checking the levels of the sewer inverts
  • Manhole covers are made circular for the convenience of the cleaning staff
  • A manhole is classified as deep manhole if its depth is more than 1.5 m
  • A manhole is classified as shallow manhole if its depth is. less than 0.9 m
  • All the above.
Q.27

The factor responsible for purification of sewage in river is

  • Hydrology
  • Dissolved oxygen in water
  • Temperature
  • Turbulence
  • All the above.
Q.28
Aerobic bacterias
  • Flourish in the presence of free oxygen
  • Consume organic matter as their food
  • Oxidise organic matter in sewage
  • All the above
Q.29
The pH value of sewage is determined with the help of
  • Imhoff Cone
  • Turbid meter
  • Potentiometer
  • None of these
Q.30
The effluent of a septic tank is
  • Fit for discharge into any open drain
  • Foul and contains dissolved and suspended solids
  • As good as that from a complete treatment
  • None of these
Q.31
A manhole is generally provided at each
  • Bend
  • Junction
  • Change of gradient
  • All the above
Q.32
The asbestos cement sewers are
  • Light in weight
  • Not structurally strong to bear large compressive stress
  • Susceptible to corrosion by sulphuric acid
  • All the above
Q.33
The sludge does not contain waste water from
  • Bath rooms
  • Wash basins
  • Kitchen sinks
  • Toilets
Q.34
In a trickling filter
  • Filtration process is used
  • Biological action is used
  • Neither A nor B
  • Both A and B
Q.35
The sewage treatment in septic tanks is due to
  • Anaerobic decomposition
  • Aerobic decomposition
  • Parasitic decomposition
  • None of these
Q.36
Flocculated particles do not change their
  • Size
  • Shape
  • Weight
  • None of these
Q.37
Removal of oil and grease from sewage, is known
  • Screening
  • Skimming
  • Filtration
  • None of these
Q.38
Drop manholes are the manholes
  • Without entry ladders
  • Without manhole covers
  • With depths more than 3.5 m
  • Having drains at different levels
Q.39
Dried sewage after treatment is used as
  • Fertilizer
  • Building material
  • Chemical for lowering O.
  • Base material for paints
Q.40
Which one of the following statements regarding septic tanks is wrong?
  • A gap of 7.5 cm between the bottom of the covering slab and the top level of scum is provided
  • The outlet invert level is kept 5 to 7.5 cm below the inlet invert level
  • The minimum width of septic level is 90 cm
  • The depth of tank is kept equal to its width
Q.41
The temperature affects the
  • Biological activity of bacteria in sewage
  • Solubility of gases in sewage
  • Viscosity of sewage
  • All the above
Q.42
Which one of the following gases is most significant as air pollutant?
  • Carbondioxide
  • Oxygen
  • Nitrogen
  • Sulphur-dioxide
Q.43
The minimum diameter of sewer to be adopted is
  • 10 cm
  • 12.5 cm
  • 15 cm
  • 25 cm
Q.44
In a sludge digestion tank if the moisture content of sludge V1 litres is reduced from p1 % to p2 % the volume V2 is
  • [(100 + P1)/(100 – P2)] V1
  • [(100 – P1)/(100 + P2)] V1
  • [(100 – P1)/(100 – P2)] V1
  • [(100 + P2)/(100 – P1)] V1
Q.45
Oxidation process results in the formation of
  • Carbon dioxide
  • Nitrates
  • Sulphates
  • All the above
Q.46
Are available in size Stoneware sewers
  • 10 cm
  • 15 cm
  • 20 cm
  • All the above
Q.47
Acid regression stage of sludge digestion at a temperature 21°C extends over a period of
  • 15 days
  • 30 days
  • 60 days
  • 90 days
Q.48
In very first stage of decomposition of the organic matter in sewage
  • Nitrites are formed
  • Nitrates are formed
  • Carbondioxide is formed
  • Ammonia is formed
Q.49
A rainfall may be classified as acidic if its pH value is less or equal to
  • 6
  • 7
  • 5
  • 6.5
Q.50
The recommended detention period for grit chambers is
  • 1 minute
  • 2 minutes
  • 3 minutes
  • 5 minutes
0 h : 0 m : 1 s