Civil Engineering - Environmental Engineering Interview Questions and Answers

Environmental Engineering Interview Questions and Answers
51.    Air binding phenomena in rapid sand filters occur due to
a)    excessive negative head
b)    mud ball formation
c)    higher turbidity in the effluent
d)    low temperature
Ans:a

52.    The percentage of filtered water, which is used for backwashing in rapid sand filters, is about
a)    0.2 to 0.4
b)    0.4 to 1.0
c)    2 to 4
d)    5 to 7
Ans:c

53.    Period of cleaning of slow sand filters is about
a)    24 - 48 hours
b)    10-12 days
c)    2-3 months
d)    1-2 year
Ans:c

54.    The rate of Alteration of pressure filters is
a)    less than that of slow sand filters
b)    in between the filtration rate of slow sand filters and rapid sand filters
c)    greater than that of rapid sand filters
d)    equal to that of slow sand filters
Ans:c

55. Double filtration is used
a)    to increase the filtration slow sand filters capacity of
b)    to increase the filtration rapid sand filters capacity of
c)    for isolated buildings like pools, hotels etc swimming
d)    all of the above
Ans:a

56. Cleaning is done by
i)    scraping and removal in filters slow sand
ii)    back washing in slow sand filters
iii)    scraping and removal in filters  rapid sand
iv)    back washing in rapid sand filters
The correct answer is
a)    (i) and (ii)
b)    (ii) and (iii)
c)    (i) and (iv)
d)    (ii) and (iv)
Ans:c

57. Disinfection of water results in
a)    removal of turbidity
b)    removal of hardness
c)    killing of disease bacteria
d)    complete sterilisation
Ans:c

58.    The disinfection efficiency of chlorine increases by
i)    decreasing the time of contact
ii)   decreasing the temperature of water
iii) increasing the temperature of water The correct answer is
a)    only (i)
b)    both (i) and (ii)
c)    both (i) and (iii)
d)    only (iii)
Ans:d

59.    Chlorine demand of water is equal to
a)    applied chlorine
b)    residual chlorine
c)    sum of applied and residual chlorine
d)    difference  of applied  and residual chlorine
Ans:d

60.   The process in which the chlorination is done beyond the break point is known as
a)    prechlorination
b)    post chlorination
c)    super chlorination
d)    break point chlorination
Ans:c
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