A river is the source of water for water supply to a town. Its water is very turbid and polluted. The correct sequence of steps for treating the river water would be:
1
pre–sedimentation → pre–chlorination → coagulation → post chlorination
2
coagulation → sedimentation → post chlorination
3
coagulation → filtration → sedimentation → post chlorination
4
sedimentation → post chlorination
5
pre–sedimentation → post–chlorination → coagulation → pre - chlorination