Q.1

The settling velocity of the particles larger than 0.mm in a settling tank of depth 2.4 is 0.m per sec. The detention period recommended for the tank, is

  • 30 minutes
  • 1 hour
  • 1 hour and 30 minutes
  • 2 hours
  • 3 hours.
Q.2

Which one of the following tests is used for testing sewer pipes :

  • water test
  • ball test
  • mirror test
  • all of these.
Q.3

The algae dies out in the zone of

  • degradation
  • active decomposition
  • recovery
  • cleaner water.
Q.4

For trunk and out-fall, the type of sewers generally used, is

  • standard egg shaped
  • circular shaped
  • horse shoe shaped
  • parabolic shaped
  • semi-elliptical shaped.
Q.5

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

  • 10.0
  • 5.0
  • 2.0
  • 0.25
Q.6

Bio-chemical oxygen demand (BOD) for the firstdays in generally referred to

  • initial demand
  • first stage demand
  • carbonaceous demand
  • all of these.
Q.7

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.8

The ratio of maximum sewage flow to average sewage flow for mains up to 1 m in diameter, is

  • 1.5
  • 2.0
  • 3.0
  • 4.0
Q.9

The width of a rectangular sewer is twice its depth while discharging 1.5 m/sec. The width of the sewer is

  • 0.68 m
  • 0.88 m
  • 1.36 m
  • 1.76 m.
Q.10

Pick up the in-correct statement from the following :

  • Manholes are provided in sewer pipes at suitable intervals
  • Catch basins are generally provided in sewers for carrying drainage discharge
  • Inlets are generally provided in all sewers
  • None of these.
Q.11

Pick up the correct statement from the following :

  • The larger the sewer in size, more will be velocity
  • The smaller the sewer in size, less will be velocity
  • The larger the sewer in size, no deposition will take place
  • The larger the sewer in size, deposition will take place.
Q.12

The drop man holes are generally provided in sewers for

  • industrial areas
  • large town ships
  • hilly town ships
  • cities in plains.
Q.13

Nitrogen cycle of sewage, is

  • Liberation of ammonia-formation of nitrites-formation of nitrates-liberation of nitrogen
  • Liberation of nitrogen-liberation of ammonia-formation of nitrites- formation of nitrates
  • Liberation of nitrogen-formation of nitrates-formation of nitrites-liberation of ammonia
  • Formation of nitrates-formation of nitrites-liberation of nitrates-liberation of nitrates
  • None of these.
Q.14

The recommended detention period for grit chambers is

  • 1 minute
  • 2 minutes
  • 3 minutes
  • 5 minutes.
Q.15

Pick up the incorrect statement from the following :

  • Septic tanks are horizontal continuous flow type of sedimentation tanks
  • Septic tanks are generally provided a detention period of 12 to 36 hours
  • Septic tanks are completely covered and high vent shafts are provided for the escape of foul gases
  • Septic tanks are generally classified as tanks which work on the principle of anaerobic decomposition
  • None of these.
Q.16

A drop manhole is provided if

  • a sewer drops from a height
  • a branch sewer joins the main sewer at higher level
  • a lamp is inserted to check obstruction
  • none of these.
Q.17

A drop manhole is provided if

  • a sewer drops from a height
  • a branch sewer joins the main sewer at higher level
  • a lamp is inserted to check obstruction
  • none of these.
Q.18

Pick up the correct statement from the following :

  • The materials separated by screens, is called screenings
  • The screenings are disposed off either by burning or by burial or by dumping
  • The process of burning the screenings, is called incineration
  • The process of burning the screenings, is known as compositing
  • All the above.
Q.19

Hydraulic mean radius is

  • mean radius of sewer
  • difference in heads between two points in circular pipes
  • mean of radii in a pipe line of varying cross-sections
  • cross-sectional area/wetted perimeter.
Q.20

The minimum recommended diameter of sewers, is

  • 5 cm
  • 10 cm
  • 15 cm
  • 20 cm.
Q.21

Pick up the correct statement from the following :

  • Indore method of composting involves decomposition under aerobic conditions
  • Bangalore method of composting involves decomposing under anaerobic conditions
  • Fully stabilised refuse by the Bangalore method of compositing is a powdery mass called humus
  • all of these.
Q.22

The most dangerous pollutant in vehicular emissions is

  • CO
  • SO2
  • CO2
  • O3.
Q.23

The detention period for plain sedimentation water tanks, is usually

  • 4 to 8 hours
  • 8 to 16 hours
  • 16 to 24 hours
  • 24 to 36 hours.
Q.24

In a city the ratio of the drainage to sewage isthe percentage discharge passing through non-monsoon periods, is

  • 5
  • 10
  • 15
  • 20
Q.25

Aerobic bacterias

  • flourish in the presence of free oxygen
  • consume organic matter as their food
  • oxidise organic matter in sewage
  • All the above.
Q.26

The liquid wastes from kitchens, bath rooms and wash basins, is not called

  • liquid waste
  • sullage
  • sewage
  • none of these.
Q.27

If the depletion of oxygen is found to be 2.5 mg/litre after incubating 2.5 ml of sewage diluted toml for 5 days at 20°C, B.O.D. of the sewage is

  • 50 mg/l
  • 100 mg/l
  • 150 mg/l
  • 200 mg/l
  • 250 mg/l.
Q.28

The rate of accumulation of sludge in septic tanks is recommended as

  • 30 litres/person/year
  • 25 litres/person/year
  • 30 litres/person/month
  • 25 litres/person/month.
Q.29

The presence of free ammonia in sewage, is detected by

  • boiling
  • adding pottassium permanganate
  • adding sulphuric acid
  • phenol-di-sulphuric acid.
Q.30

The clarigesters are

  • circular septic tanks
  • rectangular septic tanks
  • circular Imhoff double tanks with bottom hoppers
  • circular Imhoff double storey tanks without bottom hoppers.
Q.31

Ifsolution of a sewage sample is incubated for 5 days at 20°C and depletion of oxygen was found to be 5 ppm, B.O.D. of the sewage is

  • 200 ppm
  • 225 ppm
  • 250 ppm
  • None of these.
Q.32

The amount of oxygen consumed by the aerobic bacterias which cause the aerobic biological decomposition of sewage, is known

  • Bio-Chemical Oxygen Demand (B.O.D.)
  • Dissolved Oxygen (D.O.)
  • Chemical Oxygen Demand (C.O.D.)
  • None of these.
Q.33

Rate of flow of sewage is generally assumed

  • more than the rate of water supply
  • equal to the rate of water supply
  • less than the rate of water supply
  • at 150 litres per capita.
Q.34

The detention period for plain sedimentation water tanks, is usually

  • 4 to 8 hours
  • 8 to 16 hours
  • 16 to 24 hours
  • 24 to 36 hours.
Q.35

If D is the diameter of upper circular portion, the overall depth of a standard egg shaped section, is

  • D
  • 1.25 D
  • 1.5 D
  • 1.75 D
  • 2 D.
Q.36

The standard B.O.D. of water is taken for

  • 1 day
  • 2 days
  • 3 days
  • 5 days
  • 10 days.
Q.37

Maximum permissible velocity 1.5 m/sec, is adopted in drains

  • with beds of rocks and gravels
  • lined with stones
  • both (a) and (b)
  • neither (a) nor (b).
Q.38

The rainfall at any place may be determined by

  • its intensity
  • its direction
  • its frequency
  • all the above.
Q.39

The maximum diameter of sewers adopted in the designs is

  • 1.0 m
  • 2.0 m
  • 3.0 m
  • 4.0 m.
Q.40

If the peak discharge of a storm water drain (S.W. Drain) is e.xpected to exceedcumecs, the free board to be provided, is

  • 100 cm
  • 90 cm
  • 80 cm
  • 50 cm.
Q.41

In trickling filter, B.O.D. is reduced to

  • 30 to 40%
  • 40 to 60%
  • 60 to 80%
  • 80 to 90%
  • 95%.
Q.42

Sluge banks are formed if sewage is disposed of in

  • rivers
  • seas
  • lakes
  • none of these.
Q.43

PH value of sludge during alkaline regression stage, is

  • more than 7
  • less than 7
  • less than 6
  • more than 6.
Q.44

Which one of the following gases is most significant as air pollutant

  • Carbondioxide
  • Oxygen
  • Nitrogen
  • Sulphurdioxide.
Q.45

If the diameter of a sewer ismm, the gradient required for generating self cleansing velocity, is

  • 1 in 60
  • 1 in 100
  • 1 in 120
  • none of these.
Q.46

Lead caulked joints are used for laying

  • stone ware pipes
  • earthern ware pipes
  • C.I. pipes
  • G.I. pipes.
Q.47

Design period oftoyears is adopted for

  • branch sewers
  • main sewers
  • trunk sewers
  • all the above.
Q.48

The sewer which received discharge from two or more main sewers, is known as

  • a trunk sewer
  • an outfall sewer
  • a main sewer
  • an intercepting sewer.
Q.49

Depletion of ozone layer in the outer atmosphere may cause

  • lung cancer
  • skin cancer
  • bronchitis
  • heart disorder.
Q.50

The spacing of bars of perforations of fine screens used for the treatment of sewage, is

  • 2 to 3 mm
  • 3 to 5 mm
  • 5 to 8 mm
  • 8 to 10 mm.
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