Q.1

Removal of oil and grease from sewage, is known

  • screening
  • skimming
  • filtration
  • none of these.
Q.2

Chlorination of water is done for the removal of

  • bacterias
  • suspended solids
  • sediments
  • hardness.
Q.3

Clogging of sewers, is caused due to

  • silting
  • low discharge
  • greasy and oily matters
  • domestic wastes thrown in manholes
  • all the above.
Q.4

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

  • 1 in 60
  • 1 in 100
  • 1 in 120
  • none of these.
Q.5

A sewer running partially full and hurried with back filled, fails in compression due to

  • weight of the pipe
  • weight of the back fill
  • superimposed traffic loads
  • all the above.
Q.6

In sewers the highest non-scouring velocity is achieved in

  • glazed bricks sewers
  • cast iron sewers
  • cement concrete sewers
  • stone ware sewers.
Q.7

The digested sludge from septic tanks, is removed after a maximum period of

  • 3 years
  • 3.5 years
  • 4 years
  • 5 years.
Q.8

Fresh sewage may become stale in

  • one hour
  • two to three hours
  • three to four hours
  • six hours.
  • ten hours.
Q.9

For non-scouring velocity 5 m/sec, the type of sewers generally preferred to, is

  • cast iron sewers
  • cement concrete sewers
  • glazed bricks sewers
  • stone ware sewers.
Q.10

For house drainage minimum gradient is

  • 1 in 60
  • 1 in 80
  • 1 in 10
  • 1 in 400
Q.11

In a fully mechanised composting plant, involves

  • mechanized receipt
  • mechanized segregation
  • mechanized pulverising of refuse
  • all of these.
Q.12

A rainfall may be classified as acidic if its pH value is less or equal to

  • 6
  • 7
  • 5
  • 6.5
Q.13

The gas which may cause explosion in sewers, is

  • carbondioxide
  • methane
  • ammonia
  • carbon monoxide.
Q.14

For evaporation and measurement of settlable solids, the apparatus used, is

  • a jar
  • a breaker
  • a test tube
  • an Imhoff cone.
Q.15

A sewer pipe contains 1 mm sand particles of specific gravity 2.and 5 mm organic particles of specific gravity 1.the minimum velocity required for removing the sewerage, is

  • 0.30 m/sec
  • 0.35 m/sec
  • 0.40 m/sec
  • 0.45 m/sec
  • 0.50 m/sec.
Q.16

Pick up the correct statement from the following :

  • pH value indicates acidity and alkalinity of sewage
  • In acidic sewage, the pH value is less than 7
  • In alkaline sewage, the pH value is more than 7
  • Fresh sewage is generally alkaline
  • All the above.
Q.17

The dimensions of a rectangular settling tank are : lengthm, width 6 m and depth 3 m. If 2 hour detention period for tanks is recommended, the rate of flow of sewage per hour, is

  • 204 cu m
  • 208 cu m
  • 212 cu m
  • 216 cu m
  • 220 cu m.
Q.18

A manhole is classified as shallow if its depth is between

  • 0.4 to 0.5 m
  • 0.5 to 0.7 m
  • 0.7 to 0.9 m
  • 0.9 to 1.20 m
  • 1.2 to 1.50 m.
Q.19

In sewage having fully oxidised organic matter, the nitrogen exists in the form of

  • nitrites
  • nitrates
  • free ammonia
  • aluminoid nitrogen
  • none of these.
Q.20

For providing an Indian type W.C., the R.C.C. slabs in the toilet portion

  • should be sunk by 20 cm
  • should be kept 20 cm above the adjacent portion
  • should be sunk by 50 cm
  • need not be sunk.
Q.21

The dimensions of a rectangular settling tank are : lengthm, width 6 m and depth 3 m. If 2 hour detention period for tanks is recommended, the rate of flow of sewage per hour, is

  • 204 cu m
  • 208 cu m
  • 212 cu m
  • 216 cu m
  • 220 cu m.
Q.22

The small sewers are cleaned by

  • flushing
  • cane rodding
  • wooden pills
  • none of these.
Q.23

In septic tanks,

  • free board of 0.3 m may be provided
  • the baffles or tees are extended up to top level of scum
  • the clear space between the baffle top and covering slab is about 7.5 cm
  • the inlet is kept 30 cm below the sewage line and outlet is kept at a level 40% depth of the sewage
  • all the above.
Q.24

The ratio of the diameter of a circular section and the side of a square section hydraulically equivalent, is

  • 1.095
  • 1.085
  • 1.075
  • 1.065
Q.25

Disposal to sewage in large cities, is done in

  • irrigation
  • dilution
  • oxidation
  • putrifaction.
Q.26

If the side of a square sewer ismm, the diameter of a hydraulically equivalent circular section, is

  • 1045 mm
  • 1065 mm
  • 1075 mm
  • 1095 mm.
Q.27

Self-cleansing velocity is

  • velocity at dry weather flow
  • velocity of water at flushing
  • velocity at which no accumulation remains in the drains
  • velocity of water in a pressure filter.
Q.28

When drainage to sewage ratio isthe peak dry weather flow is

  • 20% of the design discharge
  • slightly less than 5% of the design discharge
  • slightly more than 5% of the design discharge
  • none of these.
Q.29

In sewers the effect of scouring is more on

  • top side
  • bottom side
  • horizontal side
  • all sides.
Q.30

In SI units the power of sound is represented in

  • kgs
  • joules
  • neutons
  • watts.
Q.31

Sewer ventilating columns are generally placed at

  • distances 150 m to 300 m
  • upper ends of branch sewers
  • every change in the size of sewers
  • all the above.
Q.32

The coagulant widely used for sewage treatment, is

  • alum
  • ferric chloride
  • ferric sulphate
  • chlorinated copperas.
Q.33

The non-clog pump which permits solid matter to pass out with the liquid sewage, is

  • centrifugal pump
  • reciprocating pump
  • pneumatic ejector
  • none of these.
Q.34

The screens are fixed

  • perpendicular to the direction of flow
  • parallel to the direction of flow
  • at an angle 30° to 60° to the direction of flow
  • none of these.
Q.35

It is customary to design a sewer for D.W.F. on the basis of

  • average demand
  • twice the average demand
  • thrice the average demand
  • four times the average demand.
Q.36

The gradient of sewers depends upon

  • velocity of flow
  • diameter of the sewer
  • discharge
  • all the above.
Q.37

Dry water flow in a combined sewer, is

  • industrial sewage
  • domestic sewage
  • storm water
  • inclusive of domestic and industrial sewage but excludes storm water.
Q.38

The sewer pipe which carries sewage from a building for immediate disposal is

  • house sewer
  • lateral sewer
  • intercepting sewer
  • main sewer.
Q.39

Pick up the correct statement from the following :

  • The maximum rate of storm run off is called peak drainage discharge
  • Rational method of estimating peak run off, may be used precisely for areas less than 50 hectares
  • The period after which the entire area starts contributing to the run off, is called the time of concentration
  • The time required by water to reach the outlet of a catchment from the most remote point, is called time of concentration
  • All the above.
Q.40

For the COD test of sewage, organic matter is oxidised by K2Cr207 in the presence of

  • H2SO4
  • HNO3
  • HCl
  • none of these.
Q.41

The ratio of minimum hourly flow to the average flow of sewage is

  • 1/4
  • 1/3
  • 1/2
  • 3/4
Q.42

For treating the sewage of a large city, you will recommend

  • a sedimentation tank and an activated sludge treatment plant
  • a plant consisting of Imhoff tanks with low rate trickling filters
  • sedimentation tanks with high rate trickling filters
  • none of these.
Q.43

A rain sanitary sewer is constructed to carry

  • sanitary sewage
  • storm sewage
  • surface water
  • ground water
  • all the above.
Q.44

For design purposes, the normal rate of infiltration of ground water into the sewer, is

  • 500 litres/km/cm
  • 1000 litres/km/cm
  • 1500 litres/km/cm
  • 2000 litres/km/cm
  • 2500 litres/km/cm.
Q.45

In case of Imhoff tanks,

  • the shape is rectangular
  • detention period is 2 hours
  • the velocity of flow is restricted to 0.30 m/minute
  • surface loading is limited to 30, 000 litres/m of plan area per day
  • All the above.
Q.46

House connections to the laterals is generally made by

  • R.C.C.
  • P.C.C.
  • Cast iron
  • Glazed stonewares.
Q.47

For design purposes, the normal rate of infiltration of ground water into the sewer, is

  • 500 litres/km/cm
  • 1000 litres/km/cm
  • 1500 litres/km/cm
  • 2000 litres/km/cm
  • 2500 litres/km/cm.
Q.48

Assertion (A) : Discharging the effluents from the oxidation ponds just up stream of lakes or reservoirs is undesirable.

Reason (R) : The discharged algae get settled in the reservoirs and cause anaerobic decomposition and other water qualities.

  • 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.49

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

  • 2.25
  • 2.50
  • 2.55
  • 2.65
  • 2.75
Q.50

During preliminary treatment of a sewage

  • Oil and grease are removed from skimming tanks
  • Floating materials are removed by screening
  • Girt and sand are removed by girt chambers
  • All the above.
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