Disinfection of water results in______________?
(A) removal of turbidity
(B) removal of hardness
(C) killing of disease bacteria
(D) complete sterilisation
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
The disinfection efficiency of chlorine increases by_______________?
(A) only (1)
(B) both (1) and (2)
(C) both (1) and (3)
(D) only (3)
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
The treatment of water with bleaching powder is known as________________?
(A) prechlorination
(B) super chlorination
(C) dechlorination
(D) hypochlorination
Which of the following chemical compounds can be used for dechlorination of water ?
(A) carbon dioxide
(B) bleaching powder
(C) sulphur dioxide
(D) chloramines
As compared to higher pH values, the contact period required for efficient chlorination at lower pH values is___________________?
(A) smaller
(B) larger
(C) same
(D) none of the above
In lime-soda process________________?
(A) only carbonate hardness is removed
(B) only non-carbonate hardness is re-moved
(C) lime reduces the carbonate hardness and soda-ash removes the non-carbo¬nate hardness
(D) lime reduces the non-carbonate hard-ness and soda-ash removes the carbo¬nate hardness
Which of the following compounds is widely used for algae control ?
(A) sodium sulphate
(B) copper sulphate
(C) sodium chloride
(D) calcium chloride
The overflow rate for plain sedimentation tanks is about__________________?
(A) 500 to 750 litres/hour/ m2
(B) 1000 to 1250 litres/hour/ m2
(C) 1250 to 1500 litres/hour/m2
(D) 1500 to 2000 litres/hour/m2