Question

Addition of Alum in water treatment increases:

• A. Acidity and hardness of water
• B. Alkalinity and hardness of water
• C. Sulphate and sulphides in water
• D. Carbonate and bicarbonates in water

Hint:

Alum is primarily used as a coagulant in water treatment to destabilize colloidal parti cles but also increases acidity

Answer 1

The Correct Option is A

Alum\( (Al_2(SO_4)_3)\) reacts with water to form sulphuric acid, which lowers the pH (increases acidity). The aluminium ions react with bicarbonates in the water, leading to the formation of insoluble precipitates that contribute to water hardness.