Consider the following statements:
1. Alum coagulation decreses the alkalinity of water.
2. Alum coagulation increases permanent hardness of water
3. Alum coagulation decreses pH of water.
4. Alum coagulation produces aluminium hydroxide flocks in the flocculation process.
Which of the statements given above the correct?
1
1, 2, 3 and 4
2
1, 3 and 4 only
3
1 and 2 only
4
2, 3 and 4 only