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This set of Water and Wastewater Engineering Multiple Choice Questions & Answers (MCQs) focuses on Water And Wastewater Engineering Set 1
Q1 | For a continuous flow type of sedimentation tanks
- Width of the tank is normally kept about 6 m
- Length of the tank is normally kept 4 to 5 times the width
- ) Maximum horizontal flow velocity is limited to 0.3 m/minute
- All the above
Q2 | 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
Q3 | For efficient working of a sewer, it must be ensured that
- Minimum velocity of 0.45 m/sec, is maintained at its minimum flow
- A maximum velocity of 0.90 m/sec, is maintained at its maximum flow
- Both (a) and (b)
- Neither (a) nor (b)
Q4 | Bottom openings 15 cm × 15 cm in the standing baffle wall are provided
- 15 cm c/c
- 22.5 cm c/c
- 30 cm c/c
- 50 cm c/c
Q5 | For drainage pipes in buildings the test applied before putting them to use, is
- Water test
- Smoke test
- Straightness test
- All the above
Q6 | The pressure exerted by
- The sewage when running full from inside, is called internal pressure
- The internal pressure if any, causes tensile stress in the pipe material
- Pressure sewers are designed to be safe in tension
- All the above
Q7 | No treatment of the sewage is given if dilution factor is
- Less than 150
- Between 150 to 200
- Between 200 to 300
- More than 500
Q8 | Which of the following pumps in used to pump sewage solids with liquid sewage withoutclogging the pump is?
- Centrifugal pump
- Pneumatic ejector
- Reciprocating pump
- None of these
Q9 | Acid regression stage of sludge digestion at a temperature 21°C extends over a period of
- 15 days
- 30 days
- ) 60 days
- 90 days
Q10 | The coagulant which is generally not used for treating the sewage, is
- Alum
- Ferric chloride
- Ferric sulphate
- Chlorinated copperas
Q11 | The layers of vegetable wastes and night soil alternatively piled above the ground to form a mound, is called
- A heap
- Plateau
- Windrow
- None of these
Q12 | If the flame of a miner's safety lamp in the upper layers of the sewer forms an explosive, thesewer certainly contains
- Hydrogen sulphide
- Carbon dioxide
- Methane
- Oxygen
Q13 | The gas which may cause explosion in sewers, is
- Carbondioxide
- Methane
- Ammonia
- Carbon monoxide
Q14 | Pick up the incorrect statement from the following:
- The process of decomposing the organic matter under controlled anaerobic conditions, is called sludge digestion
- Sludge digestion is carried out in sludge tank
- The gases produced in sludge digestion process, contain 75% carbon dioxide
- The gases produced in sludge digestion process, contain 75% methane
Q15 | The sewer pipes
- Carry sewage as gravity conduits
- Are designed for generating self-cleansing velocities at different discharge
- Should resist the wear and tear caused due to abrasion
- All the above
Q16 | The settling velocity of the particles larger than 0.06 mm in a settling tank of depth 2.4 is 0.33 mper sec. The detention period recommended for the tank, is
- 30 minutes
- 1 hour
- 1 hour and 30 minutes
- 2 hours
Q17 | The Chezy's constant C in the formula V = C ???? depends upon
- Size of the sewer
- Shape of the sewer
- Roughness of sewer surface
- All the above
Q18 | To prevent settling down of sewage both at the bottom and on the sides of a large sewer,selfcleaning velocity recommended for Indian conditions, is
- 0.50 m/sec
- 0.60 m/sec
- 0.70 m/sec
- 0.75 m/sec
Q19 | 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.
- 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
Q20 | The normal values of over flow rates for sedimentation tanks using coagulant, ranges between
- 25,000 to 35,000 litres/sqm/day
- 40,000 to 50,000 litres/sqm/day
- 50,000 to 60,000 litres/sqm/day
- 80,000 to 100,000 litres/sqm/day
Q21 | 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
Q22 | Dry weather flow is:
- Average daily rate of flow
- Average monthly rate of flow
- Average annual rate of flow
- Water supply allowance per capita
Q23 | If q is the average sewage flow from a city of population P, the maximum sewage flow
- Q = [(4 + ?? )/(18 + ?? )] q
- Q = [(18 +p )/(4 + ?? )] q
- Q = [(18 + ?? )/(4 + ?? )] q
- Q = [(5 + ?? )/(15 + ?? )] q
Q24 | If the flame of a miner's safety lamp in a manhole extinguishes within 5 minutes, the sewercertainly contains
- Hydrogen sulphide
- Carbon dioxide
- Methane
- Oxygen
Q25 | 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