Civil Engineering MCQJE Level Civil Engineering
The most commonly used primary coagulant in water treatment is:
Environmental EngineeringEnvironmental EngineeringEASY
Choose the correct answer
A
NaOH
B
Alum [Al2(SO4)3·18H2O]
C
Bleaching powder
D
Activated carbon
Correct Answer
B. Alum [Al2(SO4)3·18H2O]
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Alum [Al2(SO4)3·18H2O] is the most widely used coagulant. It hydrates to form Al(OH)3 floc that adsorbs and sweeps colloidal impurities. Optimal pH 6.5–8.0. Ferrous sulphate (FeSO4) and FeCl3 are alternatives. Coagulants destabilise colloidal particles for flocculation.
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