Hardness of water,Classification and how to remove hardness from water.

 TOPIC: Hardness of Water 

Contents:

👉Classification of Water according to hardness

👉What is Hard Water?

👉Types of Hardness of Water

👉How to remove Temporary Hardness?

👉How to remove Permanent Hardness?

👉Harmful Effects of Hard Water

👉Classification of water according to dissolved Ca and Mg present 

👉Requirement of minerals for human body

1.Classification of Water according to hardness :

2. What is hard water ? 

● Hard water (or water hardness) is a common quality of   water which contains dissolved compounds of calcium  and magnesium.

i.e  CaCO3/MgCO3

      CaHCO3/MgHCO3

      CaSO4/MgSO4

      CaNO3/MgNO3

      CaCl2/MgCl2

      CaSiO3/MgSiO3

 3.Types of hardness of water :

4.How to remove Temporary Hardness: 

● The presence of magnesium and calcium bicarbonates in water makes it temporarily hard. 

●In this case, the hardness in water can be removed by boiling the water.

●When we boil water the soluble salts of Mg(HCO3)2 is converted to Mg(OH)2 and Ca(HCO3)2 is converted to Ca(CO)3 .

● Mg(OH)2 and Ca(CO)3 are insoluble in water and hence gets precipitated and is removed. 

5.How to remove Permanent Hardness :

● We can remove permanent hardness from water by using following methods.

i.e  Ion Exchange Method(Demineralisation Plant,Softener Plant)

      Reverse Osmosis plant

      Lime soda Process

6.Harmful effects of hard water:

● Wastage of soap and detergent due to poor performance

●Formation of scales on metallic pipes ,plumbing fixtures and 

  appliances.

●Causing dry skin and hair

●Cause skin irritation

●Frequent plumbing repairs

●Rise in water consumption as well as water bills in home and industry.

●In industry rise water consumption due to blow down because to maintain water parameters in acceptable range 

7.Classification of water according to dissolved Ca and Mg present :

NB: For drinking water hardness should be 60 mg/l  to 120mg/l.

For process water hardness ,that will depend industry to industry as per requirement. They can use hard and  very hard water. 

●We can measure hardness in terms of mg/l or ppm.

8.Requirement of minerals for Human body:

●If you drink 2 liters of tap water per day % of minerals of your RDI(Recommended Daily Intake ):

10% copper

6% calcium

5% magnesium

3% sodium

and less than 1% of all other minerals.