environmental engineering MCQs – Page 3

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

environmental engineering Mcqs

41. Percentage of bacterial load that can be removed from water by the process of plain sedimentation is about_______________?
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A. 100

B. 75

C. 10 to 25

D. 50

42. The hydraulic mean depth (HMD. for an egg-shaped sewer flowing two-third full is_______________?
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A. none of the above

B. less than HMD when flowing full

C. greater than HMD when flowing full

D. equal to HMD when flowing full

43. The disinfection efficiency of chlorine increases by_______________?
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A. decreasing the time of contact

B. decreasing the temperature of water

C. increasing the temperature of water</strong>

D. correct answer is ?

E. only (1)

F. both (1) and (2)

44. The most common cause of acidity in water is_______________?
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A. nitrogen

B. oxygen

C. carbon dioxide

D. hydrogen

45. Residual chlorine in water is determined by________________?
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A. starch iodide method

B. orthotolidine method

C. both (A) and (B)

D. none of the above

46. The suitable method for disinfection of swimming pool water is________________?
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A. lime treatment

B. by using potassium permanganate

C. chlorination

D. ultra violet rays treatment

47. The dissolved oxygen level in natural unpolluted waters at normal temperature is found to be of the order of________________?
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A. 100 mg/litre

B. 1000 mg/litre

C. 1 mg/litre

D. 10 mg/litre

48. The suitable system of sanitation for area of distributed rainfall throughout the year with less intensity is_________________?
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A. partially separate system

B. combined system

C. separate system

D. partially combined system

49. The rate of filtration in slow sand filters in million litres per day per hectare is about_____________?
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A. 50 to 60

B. 100 to 150

C. 1400 to 1500

D. 500 to 600

50. The minimum and maximum diameters of sewers shall preferably be_________________?
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A. 15 cm and 300 cm

B. 15 cm and 100 cm

C. 30 cm and 450 cm

D. 60 cm and 300cm

51. The main disadvantage of cement concrete sewers is________________?
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A. difficulty in transportation due to heavy weight

B. difficulty in construction

C. less strength

D. less life

52. Orthotolidine test is used for determination of________________?
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A. residual chlorine

B. dissolved oxygen

C. biochemical oxygen demand

D. dose of coagulant

53. The process of lagooning is primarily a means of________________?
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A. increasing the capacity of storage re-servoirs

B. reducing the excessive flow in sewers

C. increasing flow of sewage through imhoff tanks

D. disposing of sludge

54. Sewage treatment units are designed for_______________?
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A. average flow only

B. maximum and minimum flow

C. maximum flow only

D. minimum flow only

55. The type of valve, which is provided on the suction pipe in a tube-well, is____________?
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A. air relief valve

B. pressure relief valve

C. reflux valve

D. sluice valve

56. The correct relation between theoretical oxygen demand (TOD), Biochemical oxygen demand (BOD) and Chemical oxygen demand (COD) is given by_______________?
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A. TOD>COD>BOD

B. TOD>BOD>COD

C. COD>BOD>TOD

D. BOD>COD>TOD

57. Double filtration is used_______________?
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A. to increase the filtration slow sand filters capacity of

B. for isolated buildings like pools, hotels etc swimming

C. all of the above

D. to increase the filtration rapid sand filters capacity of

58. The overflow rate for plain sedimentation tanks is about__________________?
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A. 500 to 750 litres/hour/ m2

B. 1500 to 2000 litres/hour/m2

C. 1000 to 1250 litres/hour/ m2

D. 1250 to 1500 litres/hour/m2

59. The chemical most commonly used to increase speed of sedimentation of sewage is_______________?
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A. sodium permanganate

B. copper sulphate

C. sulphuric acid

D. lime

60. Composting and lagooning are the methods of_______________?
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A. sedimentation

B. sludge disposal

C. sludge digestion

D. filtration

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