Here are top 50 Waste Water Engineering Multiple choice questions and answers are given just below to them. These sample Waste Water Engineering objective type questions are framed by experts. who train for Learn Waste Water Engineering Online VIVA Questions to give you an idea of Waste Water Engineering mcqs which may be asked in interview. We have taken full care to give correct answers for all the questions. Do comment your thoughts. Happy Job Hunting!
Q No: 1 For a continuous flow type of sedimentation tanks
A. Width of the tank is normally kept about 6 m
B. Length of the tank is normally kept 4 to 5 times the width
C. Maximum horizontal flow velocity is limited to 0.3 m/minute
D. All the above
ANS: D
Q No: 2 The asbestos cement sewers are
A. Light in weight
B. Not structurally strong to bear large compressive stress
C. Susceptible to corrosion by sulphuric acid
D. All the above
ANS: D
Q No: 3 For efficient working of a sewer, it must be ensured that
A. Minimum velocity of 0.45 m/sec, is maintained at its minimum flow
B. A maximum velocity of 0.90 m/sec, is maintained at its maximum flow
C. Both A. and B.
D. Neither A. nor B.
ANS: C
Q No: 4Pick up the correct statement from the following:
A. The sewer pipes of sizes less than 0.4 m diameter are designed as running full at maximum discharge
B. The sewer pipes of sizes greater than 0.4 m diameter are designed as running 2/3rd or 3/4th full at maximum discharge
C. The minimum design velocity of sewer pipes is taken as 0.8 m/sec
D. All the above
ANS: D
Q No: 5 Pick up the correct statement from the following:
A. Maximum daily flow = 2 times the average daily flow
B. Maximum daily flow = average daily flow
C. Sewers are designed for minimum permissible velocity at minimum flow
D. All the above
ANS: D
Q No: 6 Bottom openings 15 cm × 15 cm in the standing baffle wall are provided
A. 15 cm c/c
B. 22.5 cm c/c
C. 30 cm c/c
D. 50 cm c/c
ANS: B
Q No: 7 The pressure exerted by
A. The sewage when running full from inside, is called internal pressure
B. The internal pressure if any, causes tensile stress in the pipe material
C. Pressure sewers are designed to be safe in tension
D. All the above
ANS: D
Q No: 8 For drainage pipes in buildings the test applied before putting them to use, is
A. Water test
B. Smoke test
C. Straightness test
D. All the above
ANS: B
Q No: 9No treatment of the sewage is given if dilution factor is
A. Less than 150
B. Between 150 to 200
C. Between 200 to 300
D. More than 500
ANS: D
Q No: 10 Which of the following pumps in used to pump sewage solids with liquid sewage without clogging the pump is?
A. Centrifugal pump
B. Pneumatic ejector
C. Reciprocating pump
D. None of these
ANS: A
Q No: 11 Acid regression stage of sludge digestion at a temperature 21°C extends over a period of
A. 15 days
B. 30 days
C. 60 days
D. 90 days ANS: D
Q No: 12 Pick up the correct statement from the following:
A. Small sewers are cleaned by flushing
B. Medium sewers are cleaned by cane rodding
C. Medium sewers may be cleaned by pills
D. All the above
ANS: D
Q No: 13 The coagulant which is generally not used for treating the sewage, is
A. Alum
B. Ferric chloride
C. Ferric sulphate
D. Chlorinated copperas
ANS: A
Q No: 14 The layers of vegetable wastes and night soil alternatively piled above the ground to form a mound, is called
A. A heap
B. Plateau
C. Windrow
D. None of these
ANS: D
Q No: 15 If the flame of a miner’s safety lamp in the upper layers of the sewer forms an explosive, the sewer certainly contains
A. Hydrogen sulphide
B. Carbon dioxide
C. Methane
D. Oxygen
ANS: C
Q No: 16 The gas which may cause explosion in sewers, is
A. Carbondioxide
B. Methane
C. Ammonia
D. Carbon monoxide
ANS: B
Q No: 17 Pick up the correct statement from the following:
A. The water supply pipes carry pure water free from solid particles
B. The water supply pipes get clogged if flow velocity is less than self cleansing velocity
C. The sewers may be carried up and down the hills and valleys
D. The sewer pipes are generally laid along level hills
ANS: A
Q No: 18 Pick up the incorrect statement from the following:
A. The process of decomposing the organic matter under controlled anaerobic conditions, is called sludge digestion
B. Sludge digestion is carried out in sludge tank
C. The gases produced in sludge digestion process, contain 75% carbon dioxide
D. The gases produced in sludge digestion process, contain 75% methane ANS: C
Q No: 19 The sewer pipes
A. Carry sewage as gravity conduits
B. Are designed for generating self-cleansing velocities at different discharge
C. Should resist the wear and tear caused due to abrasion
D. All the above
ANS: D
Q No: 20 The settling velocity of the particles larger than 0.06 mm in a settling tank of depth 2.4 is 0.33 m per sec. The detention period recommended for the tank, is
A. 30 minutes
B. 1 hour
C. 1 hour and 30 minutes
D. 2 hours
ANS: D
Q No: 21 depends upon The Chezy’s constant C in the formula V = C
A. Size of the sewer
B. Shape of the sewer
C. Roughness of sewer surface
D. All the above
ANS: D
Q No: 22 The discharge per unit plan area of a sedimentation tank, is generally called
A. Over flow rate
B. Surface loading
C. Over flow velocity
D. All the above ANS: D
Q No: 23 Pick up the incorrect statement from the following for allowing workers to enter sewers
A. The particular manhole and one manhole on upstream and one manhole on downstream should remain open for 30 minutes
B. Proper tests for the presence of poisonous gases must be carried out C. The men entering the manhole should be advised to smoke in the sewer
D. Warning signals should be erected
ANS: C
Q No: 24 For the open drain (N = 0.025) shown in the below figure, the discharge is
A. 26.88 cumecs
B. 27.88 cumecs
C. 28.88 cumecs
D. 29.88 cumecs ANS: C
Q No: 25 To prevent settling down of sewage both at the bottom and on the sides of a large sewer, self-cleaning velocity recommended for Indian conditions, is
A. 0.50 m/sec
B. 0.60 m/sec
C. 0.70 m/sec
D. 0.75 m/sec
ANS: D
Q No: 26 Assertion A.: The determination of pH value of sewerage is important.
Reason (R): The efficiency of certain treatment methods depends upon the availability of pH value.
A. Both A and R are true and R is the correct explanation of A
B. Both A and R are true but R is not a correct explanation of A
C. A is true but R is false
D. A is false but R is true ANS: A
Q No: 27 The normal values of over flow rates for sedimentation tanks using coagulant, ranges between
A. 25,000 to 35,000 litres/sqm/day
B. 40,000 to 50,000 litres/sqm/day
C. 50,000 to 60,000 litres/sqm/day
D. 80,000 to 100,000 litres/sqm/day
ANS: C
Q No: 28 The drainage area of a town is 12 hectares. Its 40% area is hard pavement ( K = 0.85), the 40% area is unpaved streets (K = 0.20) and the remaining is wooded areas (K = 0.15). Assuming the time of concentration for the areas as 30 minutes and using the formula Ps = 900/(t + 60) the maximum run off is
A. 0.10 cumec
B. 0.12 cumec
C. 0.15 cumec
D. 0.20 cumec
ANS: C
Q No: 29 Sewer pipes are designed for maximum discharge with 25% to 33% vacant cross-sectional area for
A. Unexpected large scale infiltration of stream water
B. Unexpected increase in the population
C. Under estimates of maximum and average flows
D. All of the above
ANS: D
Q No: 30 The rational formula for peak drainage discharge, was evolved by
A. Fruhling
B. Lloyd David
C. Kuichling
D. All of these
ANS: D
Q No: 31 The sewer that unloads the sewage at the point of treatment is called
A. Main sewer
B. Outfall sewer
C. Branch sewer
D. House sewer
ANS: B
Q No: 32 During preliminary treatment of a sewage
A. Oil and grease are removed from skimming tanks
B. Floating materials are removed by screening
C. Girt and sand are removed by girt chambers
D. All the above
ANS: D
Q No: 33 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
A. 16 m
B. 20 m
C. 24 m
D. 30 m
ANS: C
Q No: 34 Dry weather flow is:
A. Average daily rate of flow
B. Average monthly rate of flow
C. Average annual rate of flow
D. Water supply allowance per capita
ANS: D
Q No: 35 Pick up the incorrect statement from the following:
A. The mixture of water and waste products, is called sewage
B. The treated sewage effluents, are generally used for irrigating the crops
C. The process of collecting, treating and disposing off the sewage, is called sewerage
D. The old convergence system was definitely better than water carried sewerage system
ANS: D
Q No: 36 Pick up the correct statement from the following:
A. The maximum rate of storm runoff is called peak drainage discharge
B. Rational method of estimating peak run off, may be used precisely for areas less than 50 hectares
C. The period after which the entire area starts contributing to the runoff, is called the time of concentration
D. All the above
ANS: D
Q No: 37 If q is the average sewage flow from a city of population P, the maximum sewage flow
A. Q = [(4 + )/(18 + )] q
B. Q = [(18 + P)/(4 + )] q
C. Q = [(18 + )/(4 + )] q
D. Q = [(5 + )/((15 + )] q
ANS: C
Q No: 38 ¾th or ¼th extra space is left in sewer pipes at maximum discharge for
A. Low estimates of the average and maximum flows
B. Large scale infiltration of storm water
C. Unexpected increase in population
D. All the above
ANS: D
Q No: 39 If the flame of a miner’s safety lamp in a manhole extinguishes within 5 minutes, the sewer certainly contains
A. Hydrogen sulphide
B. Carbon dioxide
C. Methane
D. Oxygen
ANS: B
Q No: 40 Hydraulic mean radius is
A. Mean radius of sewer
B. Difference in heads between two points in circular pipes
C. Mean of radii in a pipe line of varying cross -sections
D. Cross-sectional area/wetted perimeter
ANS: D
Q No: 41 If the depth of flow in a circular sewer is 1/4th of its diameter D, the wetted perimeter is
A. /2
B. /4
C. /3
D. D
ANS: C
Q No: 42 Pick up the correct statement from the following:
A. Anaerobic bacteria flourish in the absence of oxygen
B. Aerobic bacteria flourish in the presence of oxygen
C. Facultative bacteria flourish with or without oxygen
D. All the above
ANS: D
The Brake Horse power of the motor (efficiency 60%) required for a pump of capacity 0.075 cumecfor a total lift of 12 m, is
A. 10
B. 15
C. 20
D. 25
Q No: 44 Aerobic bacterias
A. Flourish in the presence of free oxygen
B. Consume organic matter as their food
C. Oxidise organic matter in sewage
D. All the above
ANS: D
Q No: 45 At the junction of sewers
A. Top of smaller sewer is kept lower
B. Top of larger sewer is kept lower
C. Tops of both the sewers are at the same level
D. None of these
ANS: D
Q No: 46 Traps
A. Are water seals which prevent the entry of foul gases
B. Are used to trap the rats entering sewers
C. Dissolve the foul gases
D. Create symphonic action to increase the quick disposal of sewerage ANS: A
Q No: 47 The sewage treatment units in which anaerobic decomposition of organic matter is used, are called
A. Imhoff tanks
B. Trickling filters
C. Sludge sedimentation tanks
D. None of these
ANS: B
Q No: 48 Pick up the correct statement from the following:
A. In treated sewage, 4 ppm of D.O. is essential
B. Only very fresh sewage contains some dissolved oxygen
C. The solubility of oxygen in sewage is 95% that is in distilled water
D. All the above
ANS: D
Q No: 49 If the diameter of a sewer is 150 mm, the gradient required for generating self cleansing velocity, is
A. 1 in 60
B. 1 in 100
C. 1 in 120
D. None of these ANS: B
Q No: 50 The sewer which received discharge from two or more main sewers, is known as
A. A trunk sewer
B. An outfall sewer
C. A main sewer
D. An intercepting sewer
ANS: A
Q No: 1 For a continuous flow type of sedimentation tanks
A. Width of the tank is normally kept about 6 m
B. Length of the tank is normally kept 4 to 5 times the width
C. Maximum horizontal flow velocity is limited to 0.3 m/minute
D. All the above
ANS: D
Q No: 2 The asbestos cement sewers are
A. Light in weight
B. Not structurally strong to bear large compressive stress
C. Susceptible to corrosion by sulphuric acid
D. All the above
ANS: D
Q No: 3 For efficient working of a sewer, it must be ensured that
A. Minimum velocity of 0.45 m/sec, is maintained at its minimum flow
B. A maximum velocity of 0.90 m/sec, is maintained at its maximum flow
C. Both A. and B.
D. Neither A. nor B.
ANS: C
Q No: 4Pick up the correct statement from the following:
A. The sewer pipes of sizes less than 0.4 m diameter are designed as running full at maximum discharge
B. The sewer pipes of sizes greater than 0.4 m diameter are designed as running 2/3rd or 3/4th full at maximum discharge
C. The minimum design velocity of sewer pipes is taken as 0.8 m/sec
D. All the above
ANS: D
Q No: 5 Pick up the correct statement from the following:
A. Maximum daily flow = 2 times the average daily flow
B. Maximum daily flow = average daily flow
C. Sewers are designed for minimum permissible velocity at minimum flow
D. All the above
ANS: D
Q No: 6 Bottom openings 15 cm × 15 cm in the standing baffle wall are provided
A. 15 cm c/c
B. 22.5 cm c/c
C. 30 cm c/c
D. 50 cm c/c
ANS: B
Q No: 7 The pressure exerted by
A. The sewage when running full from inside, is called internal pressure
B. The internal pressure if any, causes tensile stress in the pipe material
C. Pressure sewers are designed to be safe in tension
D. All the above
ANS: D
Q No: 8 For drainage pipes in buildings the test applied before putting them to use, is
A. Water test
B. Smoke test
C. Straightness test
D. All the above
ANS: B
Q No: 9No treatment of the sewage is given if dilution factor is
A. Less than 150
B. Between 150 to 200
C. Between 200 to 300
D. More than 500
ANS: D
Q No: 10 Which of the following pumps in used to pump sewage solids with liquid sewage without clogging the pump is?
A. Centrifugal pump
B. Pneumatic ejector
C. Reciprocating pump
D. None of these
ANS: A
Q No: 11 Acid regression stage of sludge digestion at a temperature 21°C extends over a period of
A. 15 days
B. 30 days
C. 60 days
D. 90 days ANS: D
Q No: 12 Pick up the correct statement from the following:
A. Small sewers are cleaned by flushing
B. Medium sewers are cleaned by cane rodding
C. Medium sewers may be cleaned by pills
D. All the above
ANS: D
Q No: 13 The coagulant which is generally not used for treating the sewage, is
A. Alum
B. Ferric chloride
C. Ferric sulphate
D. Chlorinated copperas
ANS: A
Q No: 14 The layers of vegetable wastes and night soil alternatively piled above the ground to form a mound, is called
A. A heap
B. Plateau
C. Windrow
D. None of these
ANS: D
Q No: 15 If the flame of a miner’s safety lamp in the upper layers of the sewer forms an explosive, the sewer certainly contains
A. Hydrogen sulphide
B. Carbon dioxide
C. Methane
D. Oxygen
ANS: C
Q No: 16 The gas which may cause explosion in sewers, is
A. Carbondioxide
B. Methane
C. Ammonia
D. Carbon monoxide
ANS: B
Q No: 17 Pick up the correct statement from the following:
A. The water supply pipes carry pure water free from solid particles
B. The water supply pipes get clogged if flow velocity is less than self cleansing velocity
C. The sewers may be carried up and down the hills and valleys
D. The sewer pipes are generally laid along level hills
ANS: A
Q No: 18 Pick up the incorrect statement from the following:
A. The process of decomposing the organic matter under controlled anaerobic conditions, is called sludge digestion
B. Sludge digestion is carried out in sludge tank
C. The gases produced in sludge digestion process, contain 75% carbon dioxide
D. The gases produced in sludge digestion process, contain 75% methane ANS: C
Q No: 19 The sewer pipes
A. Carry sewage as gravity conduits
B. Are designed for generating self-cleansing velocities at different discharge
C. Should resist the wear and tear caused due to abrasion
D. All the above
ANS: D
Q No: 20 The settling velocity of the particles larger than 0.06 mm in a settling tank of depth 2.4 is 0.33 m per sec. The detention period recommended for the tank, is
A. 30 minutes
B. 1 hour
C. 1 hour and 30 minutes
D. 2 hours
ANS: D
Q No: 21 depends upon The Chezy’s constant C in the formula V = C
A. Size of the sewer
B. Shape of the sewer
C. Roughness of sewer surface
D. All the above
ANS: D
Q No: 22 The discharge per unit plan area of a sedimentation tank, is generally called
A. Over flow rate
B. Surface loading
C. Over flow velocity
D. All the above ANS: D
Q No: 23 Pick up the incorrect statement from the following for allowing workers to enter sewers
A. The particular manhole and one manhole on upstream and one manhole on downstream should remain open for 30 minutes
B. Proper tests for the presence of poisonous gases must be carried out C. The men entering the manhole should be advised to smoke in the sewer
D. Warning signals should be erected
ANS: C
Q No: 24 For the open drain (N = 0.025) shown in the below figure, the discharge is
A. 26.88 cumecs
B. 27.88 cumecs
C. 28.88 cumecs
D. 29.88 cumecs ANS: C
Q No: 25 To prevent settling down of sewage both at the bottom and on the sides of a large sewer, self-cleaning velocity recommended for Indian conditions, is
A. 0.50 m/sec
B. 0.60 m/sec
C. 0.70 m/sec
D. 0.75 m/sec
ANS: D
Q No: 26 Assertion A.: The determination of pH value of sewerage is important.
Reason (R): The efficiency of certain treatment methods depends upon the availability of pH value.
A. Both A and R are true and R is the correct explanation of A
B. Both A and R are true but R is not a correct explanation of A
C. A is true but R is false
D. A is false but R is true ANS: A
Q No: 27 The normal values of over flow rates for sedimentation tanks using coagulant, ranges between
A. 25,000 to 35,000 litres/sqm/day
B. 40,000 to 50,000 litres/sqm/day
C. 50,000 to 60,000 litres/sqm/day
D. 80,000 to 100,000 litres/sqm/day
ANS: C
Q No: 28 The drainage area of a town is 12 hectares. Its 40% area is hard pavement ( K = 0.85), the 40% area is unpaved streets (K = 0.20) and the remaining is wooded areas (K = 0.15). Assuming the time of concentration for the areas as 30 minutes and using the formula Ps = 900/(t + 60) the maximum run off is
A. 0.10 cumec
B. 0.12 cumec
C. 0.15 cumec
D. 0.20 cumec
ANS: C
Q No: 29 Sewer pipes are designed for maximum discharge with 25% to 33% vacant cross-sectional area for
A. Unexpected large scale infiltration of stream water
B. Unexpected increase in the population
C. Under estimates of maximum and average flows
D. All of the above
ANS: D
Q No: 30 The rational formula for peak drainage discharge, was evolved by
A. Fruhling
B. Lloyd David
C. Kuichling
D. All of these
ANS: D
Q No: 31 The sewer that unloads the sewage at the point of treatment is called
A. Main sewer
B. Outfall sewer
C. Branch sewer
D. House sewer
ANS: B
Q No: 32 During preliminary treatment of a sewage
A. Oil and grease are removed from skimming tanks
B. Floating materials are removed by screening
C. Girt and sand are removed by girt chambers
D. All the above
ANS: D
Q No: 33 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
A. 16 m
B. 20 m
C. 24 m
D. 30 m
ANS: C
Q No: 34 Dry weather flow is:
A. Average daily rate of flow
B. Average monthly rate of flow
C. Average annual rate of flow
D. Water supply allowance per capita
ANS: D
Q No: 35 Pick up the incorrect statement from the following:
A. The mixture of water and waste products, is called sewage
B. The treated sewage effluents, are generally used for irrigating the crops
C. The process of collecting, treating and disposing off the sewage, is called sewerage
D. The old convergence system was definitely better than water carried sewerage system
ANS: D
Q No: 36 Pick up the correct statement from the following:
A. The maximum rate of storm runoff is called peak drainage discharge
B. Rational method of estimating peak run off, may be used precisely for areas less than 50 hectares
C. The period after which the entire area starts contributing to the runoff, is called the time of concentration
D. All the above
ANS: D
Q No: 37 If q is the average sewage flow from a city of population P, the maximum sewage flow
A. Q = [(4 + )/(18 + )] q
B. Q = [(18 + P)/(4 + )] q
C. Q = [(18 + )/(4 + )] q
D. Q = [(5 + )/((15 + )] q
ANS: C
Q No: 38 ¾th or ¼th extra space is left in sewer pipes at maximum discharge for
A. Low estimates of the average and maximum flows
B. Large scale infiltration of storm water
C. Unexpected increase in population
D. All the above
ANS: D
Q No: 39 If the flame of a miner’s safety lamp in a manhole extinguishes within 5 minutes, the sewer certainly contains
A. Hydrogen sulphide
B. Carbon dioxide
C. Methane
D. Oxygen
ANS: B
Q No: 40 Hydraulic mean radius is
A. Mean radius of sewer
B. Difference in heads between two points in circular pipes
C. Mean of radii in a pipe line of varying cross -sections
D. Cross-sectional area/wetted perimeter
ANS: D
Q No: 41 If the depth of flow in a circular sewer is 1/4th of its diameter D, the wetted perimeter is
A. /2
B. /4
C. /3
D. D
ANS: C
Q No: 42 Pick up the correct statement from the following:
A. Anaerobic bacteria flourish in the absence of oxygen
B. Aerobic bacteria flourish in the presence of oxygen
C. Facultative bacteria flourish with or without oxygen
D. All the above
ANS: D
The Brake Horse power of the motor (efficiency 60%) required for a pump of capacity 0.075 cumecfor a total lift of 12 m, is
A. 10
B. 15
C. 20
D. 25
Q No: 44 Aerobic bacterias
A. Flourish in the presence of free oxygen
B. Consume organic matter as their food
C. Oxidise organic matter in sewage
D. All the above
ANS: D
Q No: 45 At the junction of sewers
A. Top of smaller sewer is kept lower
B. Top of larger sewer is kept lower
C. Tops of both the sewers are at the same level
D. None of these
ANS: D
Q No: 46 Traps
A. Are water seals which prevent the entry of foul gases
B. Are used to trap the rats entering sewers
C. Dissolve the foul gases
D. Create symphonic action to increase the quick disposal of sewerage ANS: A
Q No: 47 The sewage treatment units in which anaerobic decomposition of organic matter is used, are called
A. Imhoff tanks
B. Trickling filters
C. Sludge sedimentation tanks
D. None of these
ANS: B
Q No: 48 Pick up the correct statement from the following:
A. In treated sewage, 4 ppm of D.O. is essential
B. Only very fresh sewage contains some dissolved oxygen
C. The solubility of oxygen in sewage is 95% that is in distilled water
D. All the above
ANS: D
Q No: 49 If the diameter of a sewer is 150 mm, the gradient required for generating self cleansing velocity, is
A. 1 in 60
B. 1 in 100
C. 1 in 120
D. None of these ANS: B
Q No: 50 The sewer which received discharge from two or more main sewers, is known as
A. A trunk sewer
B. An outfall sewer
C. A main sewer
D. An intercepting sewer
ANS: A
