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.
