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Focused topic practice

waste water engineering MCQs

Practise focused waste water engineering questions with marked answers for exam preparation and subject revision.

waste water engineering Mcqs
1. Pick up the correct statement from the following?
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A. All the above

B. 4 ppm of Dissolved Oxygen (D.O.) is ensured before discharging the treated sewage in river

C. Hydrogen sulphide gas in excess, may cause corrosion of concrete sewers

D. Solubility of oxygen in sewage is 95% of that of distilled water

2. Dry weather flow is__________________?
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A. Average daily rate of flow

B. Water supply allowance per capita

C. Average monthly rate of flow

D. Average annual rate of flow

3. Which of the following pumps in used to pump sewage solids with liquid sewage without clogging the pump is ?
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A. None of these

B. Centrifugal pump

C. Pneumatic ejector

D. Reciprocating pump

4. For drainage pipes in buildings the test applied before putting them to use, is__________________?
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A. Water test

B. Straightness test

C. Smoke test

D. All the above

5. The pressure exerted by_____________?
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A. Pressure sewers are designed to be safe in tension

B. All the above

C. The internal pressure if any, causes tensile stress in the pipe material

D. The sewage when running full from inside, is called internal pressure

6. Acid regression stage of sludge digestion at a temperature 21C extends over a period of______________?
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A. 30 days

B. 90 days

C. 60 days

D. 15 days

7. Hydraulic mean radius is_______________?
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A. Mean of radii in a pipe line of varying cross -sections

B. Mean radius of sewer

C. Difference in heads between two points in circular pipes

D. Cross-sectional area/wetted perimeter
8. The asbestos cement sewers are_________________?
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A. Susceptible to corrosion by sulphuric acid

B. Not structurally strong to bear large compressive stress

C. Light in weight

D. All the above
9. For a continuous flow type of sedimentation tanks__________________?
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A. Length of the tank is normally kept 4 to 5 times the width

B. Width of the tank is normally kept about 6 m

C. Maximum horizontal flow velocity is limited to 0.3 m/minute

D. All the above
10. For treating the sewage of a large city, you will recommend_________________?
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A. Sedimentation tanks with high rate trickling filters

B. A plant consisting of Imhoff tanks with low rate trickling filters

C. None of these

D. A sedimentation tank and an activated sludge treatment plant
11. The sewer which received discharge from two or more main sewers, is known as_______________?
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A. A trunk sewer

B. A main sewer

C. An intercepting sewer

D. An outfall sewer

12. 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__________________?
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A. 0.10 cumec

B. 0.12 cumec

C. 0.15 cumec

D. 0.20 cumec

13. R.M.O. expenses include___________________?
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A. Running expenses

B. Maintenance expenses

C. All the above

D. Operation expenses

14. No treatment of the sewage is given if dilution factor is_____________?
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A. More than 500

B. Less than 150

C. Between 200 to 300

D. Between 150 to 200

15. th or th extra space is left in sewer pipes at maximum discharge for_________________?
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A. Unexpected increase in population

B. Low estimates of the average and maximum flows

C. Large scale infiltration of storm water

D. All the above
16. The rational formula for peak drainage discharge, was evolved by_________________?
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A. Fruhling

B. Kuichling

C. All of these

D. Lloyd David

17. The rainfall at any place may be determined by__________________?
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A. Its intensity

B. All the above

C. Its direction

D. Its frequency

18. The coagulant which is generally not used for treating the sewage, is__________________?
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A. Ferric chloride

B. Ferric sulphate

C. Chlorinated copperas

D. Alum
19. Bottom openings 15 cm 15 cm in the standing baffle wall are provided________________?
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A. 22.5 cm c/c

B. 15 cm c/c

C. 50 cm c/c

D. 30 cm c/c

20. If the flame of a miners safety lamp in the upper layers of the sewer forms an explosive, the sewer certainly contains_______________?
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A. Methane

B. Hydrogen sulphide

C. Carbon dioxide

D. Oxygen

21. The Chezys constant C in the formula V = C_________________?
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A. Shape of the sewer

B. Roughness of sewer surface

C. Size of the sewer

D. All the above
22. Pick up the correct statement from the following ?
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A. Rate of digestion of sludge is more at higher temperature

B. Thermophilic organisms digest the sludge if the temperature ranges from 40 to 60C

C. Mesophilic organisms digest the sludge if the temperature is between 25 and 40C

D. All the above
23. Traps_________________?
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A. Dissolve the foul gases

B. Create symphonic action to increase the quick disposal of sewerage

C. Are used to trap the rats entering sewers

D. Are water seals which prevent the entry of foul gases
24. 1000 kg of sewage contains________________?
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A. 0.112 kg in suspension

B. 0.112 kg in solution

C. 0.225 kg in solution

D. Both A. and C. of above
25. For efficient working of a sewer, it must be ensured that _____________?
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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.

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________________?
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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

27. Aerobic bacterias___________________?
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A. Consume organic matter as their food

B. Oxidise organic matter in sewage

C. All the above

D. Flourish in the presence of free oxygen

28. For the open drain (N = 0.025) shown in the below figure, the discharge is________________?
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A. 28.88 cumecs

B. 29.88 cumecs

C. 26.88 cumecs

D. 27.88 cumecs

29. Pick up the correct statement from the following ?
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A. All the above

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. The sewer pipes of sizes less than 0.4 m diameter are designed as running full at maximum discharge

30. The sludge does not contain waste water from_________________?
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A. Wash basins

B. Bath rooms

C. Toilets

D. Kitchen sinks

31. The porosity of sediments in sewer pipes, is usually taken as___________________?
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A. 0.01

B. 0.011

C. 0.013

D. 0.012

32. For detecting the nitrates in sewage, the colour may be developed by adding________________?
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A. None of these

B. Potassium permanganate

C. Phenol-di -sulphuric acid and potassium hydroxide

D. Sulphuric acid and napthamine

33. For house drainage minimum gradient is__________________?
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A. 1 in 60

B. 1 in 80

C. 1 in 10

D. 1 in 400

34. 15 cumecs, the depth d and width are related by For drains up to___________________?
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A. B = 0.5 d

B. d = 0.2 B

C. B = 0.2 d

D. d = 0.5 B
35. The density of population over 40 hectares is 250/hectare. If water supply demand per day is 200 litres and sewage discharge is 80% of water supply, the sewage flow in sewers of separate system, is_____________________?
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A. 0.05556 cumec

B. 0.05554 cumec

C. 0.0556 cumec

D. 0.05552 cumec

36. In trickling filter, B.O.D. is reduced to___________________?
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A. 40 to 60%

B. 30 to 40%

C. 60 to 80%

D. 80 to 90%

37. The coagulant widely used for sewage treatment, is_________________?
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A. Ferric sulphate

B. Ferric chloride

C. Chlorinated copperas

D. Alum

38. The rate of accumulation of sludge in septic tanks is recommended as____________________?
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A. 25 litres/person/year

B. 30 litres/person/month

C. 30 litres/person/year

D. 25 litres/person/month

39. The maximum diameter of sewers adopted in the designs is_______________?
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A. 4.0 m

B. 2.0 m

C. 1.0 m

D. 3.0 m
40. For laying a sewer line in a trench of 2 m width, an offset line is marked on the ground parallel to the given centre line at a distance of___________________?
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A. 160 cm

B. 140 cm

C. 100 cm

D. 120 cm

41. Before discharging the foul sewage into rivers, it is generally treated by_____________________?
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A. All the above

B. Screening

C. Sedimentation

D. Oxidation

42. For sewers, inverted siphon is provided for___________________?
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A. One pipe

B. Three pipes

C. Two pipes

D. Four pipes

43. If the diameter of sewer is 225 mm, the gradient required for generating self cleansing velocity, is___________________?
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A. 1 in 100

B. 1 in 60

C. None of these

D. 1 in 120
44. The flow velocity in detritus tanks is________________?
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A. 0.05 m/sec

B. 0.09 m/sec

C. None of these

D. 1.25 m/sec

45. The ratio of maximum sewage flow to average sewage flow for mains up to 1 m in diameter, is___________________?
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A. 2.0

B. 1.5

C. 4

D. 3

46. For evaporation and measurement of settable solids, the apparatus used, is________________?
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A. A test tube

B. A breaker

C. A jar

D. An Imhoff cone
47. The sewer pipes__________________?
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A. All the above

B. Are designed for generating self-cleansing velocities at different discharge

C. Carry sewage as gravity conduits

D. Should resist the wear and tear caused due to abrasion

48. The most effective arrangement for diverting excess storm water into a natural drainage, is____________________?
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A. None of these

B. Overflow weir

C. Leaping weir

D. Siphon spill way
49. Removal of oil and grease from sewage, is known____________________?
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A. Screening

B. None of these

C. Filtration

D. Skimming
50. 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?
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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