Environmental Engineering Interview Questions and Answers pdf free download
41. The amount of coagulant needed for coagulation of water increases with
i) increase in turbidity of water
ii) decrease in turbidity of water
iii) increase in temperature of water
iv) decrease in temperature of water
The correct answer is
a) (i) and (ii)
b) (i)and(iv)
c) (ii) and (iii)
d) (ii) and (iv)
Ans:b
42. Alum as a coagulant is found to be most effective when pH range of water is
a) 2 to 4
b) 4 to 6
c) 6 to 8
d) 8 to 10
Ans:c
43. The detention period in coagulation tanks is usually kept as
a) 1 to 2 minutes
b) 30 to 45 minutes
c) 2 to 6 hours
d) 2 to 6 days
Ans:c
44. The alum, when added as a coagulant in water
a) does not require alkalinity in water for flocculation
b) does not affect pH value of water
c) increases pH value of water
d) decreases pH value of water
Ans:d
45. The chemical most commonly used to increase speed of sedimentation of sewage is
a) sulphuric acid
b) copper sulphate
c) lime
d) sodium permanganate
Ans:c
46. In water treatment, rapid gravity filters are adopted to remove
a) dissolved organic substances
b) dissolved solids and dissolved gases
c) floating solids and dissolved inorganic solids
d) bacteria and colloidal solids
Ans:d
47. The rate of filtration in slow sand filters in million litres per day per hectare is about
a) 50 to 60
b) 100 to 150
c) 500 to 600
d) 1400 to 1500
Ans:a
48. The effective size of sand particles used in slow sand filters is
a) 0.25 to 0.35 mm
b) 0.35 to 0.60 mm
c) 0.60 to 1.00 mm
d) 1.00 to 1.80 mm
Ans:a
49. As compared to rapid sand filters, slow sand filters give
i) slower filtration rate
ii) higher filtration rate
iii) lesser efficiency in removal of bacteria
iv) higher efficiency in removal of bacteria The correct answer is
a) (i) and (ii)
b) (ii) and (iii)
c) (i) and (iv)
d) (ii) and (iv)
Ans:c
50. Assertion A: Slow sand filters are more efficient in removal of bacteria than rapid sand filters.
Reason R : The sand used in slow sand filters is finer than that in rapid sand filters.
Select your answer based on the coding system given below:
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 the correct explanation of A.
c) A is true but R is false.
d) A is false but R is true.
Ans:a
41. The amount of coagulant needed for coagulation of water increases with
i) increase in turbidity of water
ii) decrease in turbidity of water
iii) increase in temperature of water
iv) decrease in temperature of water
The correct answer is
a) (i) and (ii)
b) (i)and(iv)
c) (ii) and (iii)
d) (ii) and (iv)
Ans:b
42. Alum as a coagulant is found to be most effective when pH range of water is
a) 2 to 4
b) 4 to 6
c) 6 to 8
d) 8 to 10
Ans:c
43. The detention period in coagulation tanks is usually kept as
a) 1 to 2 minutes
b) 30 to 45 minutes
c) 2 to 6 hours
d) 2 to 6 days
Ans:c
44. The alum, when added as a coagulant in water
a) does not require alkalinity in water for flocculation
b) does not affect pH value of water
c) increases pH value of water
d) decreases pH value of water
Ans:d
45. The chemical most commonly used to increase speed of sedimentation of sewage is
a) sulphuric acid
b) copper sulphate
c) lime
d) sodium permanganate
Ans:c
46. In water treatment, rapid gravity filters are adopted to remove
a) dissolved organic substances
b) dissolved solids and dissolved gases
c) floating solids and dissolved inorganic solids
d) bacteria and colloidal solids
Ans:d
47. The rate of filtration in slow sand filters in million litres per day per hectare is about
a) 50 to 60
b) 100 to 150
c) 500 to 600
d) 1400 to 1500
Ans:a
48. The effective size of sand particles used in slow sand filters is
a) 0.25 to 0.35 mm
b) 0.35 to 0.60 mm
c) 0.60 to 1.00 mm
d) 1.00 to 1.80 mm
Ans:a
49. As compared to rapid sand filters, slow sand filters give
i) slower filtration rate
ii) higher filtration rate
iii) lesser efficiency in removal of bacteria
iv) higher efficiency in removal of bacteria The correct answer is
a) (i) and (ii)
b) (ii) and (iii)
c) (i) and (iv)
d) (ii) and (iv)
Ans:c
50. Assertion A: Slow sand filters are more efficient in removal of bacteria than rapid sand filters.
Reason R : The sand used in slow sand filters is finer than that in rapid sand filters.
Select your answer based on the coding system given below:
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 the correct explanation of A.
c) A is true but R is false.
d) A is false but R is true.
Ans:a
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