Lecture - 6
HARDNESS OF WATER & ITS
TREATMENT
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Dr.Shahid Mahmood
Assistant Professor
Department of Community Medicine
Fatima Jinnah Medical College Lahore

ACKNOWLEDGEMENTS
 Park K. Textbook of Preventive and Social
Medicine
 Iliyas - Shah Public health and Community
Medicine
 Maxcy- Rosenau-Last. Public health and
Preventive Medicine
o World Health Organization (WHO)
o www.google.com/ images
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SESSION PLAN
Recap
1. Factors associated with water hardness
2. Methods how to treat hard water.
3. Hazards related to hardness of water
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RECAP
Q. Action of Chlorine for disinfection of water is
maximum when water pH is around :
A. 3.0
B. 5.0
Double pot method of well
C. 7.0 disinfection
D. 9.0
Answer : C
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Q.2 Action of Chlorine for disinfection depends
upon :
A. pH
B. Temperature
C. Contact time
D. All of the above
Chloramines
Free Residual Cl
Answer : D Break
point
5
Chlorine added

MODIFIED BRADLEY- FEACHEM CLASSIFICATION
S# Types of diseases Features
1 Faeco -oral diseases Routes of transmission. Diarrhoel diseases ,
dysentry , hepatitis A
2 Water borne diseases Contamination of water by animal and human
faeces, urine . Cholera, typhoid ,leptospirosis
3 Water washed diseases Scarcity and inaccessibility of water. Non-washing
of hand, skin. Typhus, scabies,
4 Water based diseases Water provides habitat for intermediate host.
Schistosomiasis, liver flukes, dracunculiasis
5 Water related vector Malaria, Filariasis, dengue , yellow fever , river
diseases blindness [ mosquito and fly breeding sites in
water]
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6 Water dispersed diseases Legionella infection. Bacetria resides in air
conditioning water system , fresh water amoeba

WATER RELATED NON- INFECTIOUS DISEASES
S# Agents Diseases
1 Iodine Deficient in water Goiter , Hypothyroidism
2 Excess fluoride Dental Fluorosis
3 Fluoride Deficiency Dental Caries
4 Excess Inorganic salts Diarrhea
5 Cadmium Gastric upsets , Nephropathy
6 Sodium Hypertension
7 Sulfates Laxative effect
8 Nitrates and Nitrites Methaemoglobinemia
9 lead Lead poisoning
10 Arsenic Skin and lung diseases
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11 Mercury Nephropathy

BOTTLED WATER
Drinking water that is sold for human
consumption in sanitary container.
 Plain bottled drinking water should
not contain any sweetener, chemical
additives.
 It should be calorie free and sugar
free.
 Bottled water containing less than
250 PPM total dissolved solids is
called ‘ Mineral Water’ 8

HARDNESS OF WATER
 Soap –destroying
power of water
 Large quantities of
soap or detergent
required to produce
foam /lather
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ORIGIN OF HARDNESS - MECHANISM
From Rocks &
land , sediments
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WHAT CAUSED THE HARDNESS OF WATER?
Mainly due to Four Dissolved Compounds :
1. Calcium Bicarbonate
2. Magnesium Bicarbonate
3. Calcium Sulphate
4. Magnesium Sulphate
Less Common:
1. Calcium Chlorides and Nitrates
2. Magnesium Chloride and Nitrates
3. Iron and Manganese salts
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4. Aluminium Compounds

HOW HARDNESS CLASSIFIED?
Hardness of water
Non-Carbonate
Carbonate Hardness hardness
(Temporary Hardness) (Permanent Hardness)
Calcium & Magnesium Calcium Sulphate
Bicarbonates Magnesium Sulphate
Calcium Nitrates
Magnesium Nitrates
Calcium and Magnesium
Chlorides 12

MEASUREMENT OF HARDNESS
 Expressed as milli -equivalent per litre (m Eq/l) or mg/L
 1 mEq /l of hardness = 50mg CaCO3 (50ppm) in one
litre
mEq/L 1 3 6
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BAD THINGS ABOUT HARDNESS
( DISADVANTAGES)
 Consumes More soap and detergent -
Financial loss.
 When water boiled , Carbonates precipitates
, deposited in boiler , require more energy for
heating: Industrial loss and boiler inefficiency
, may explode
 Shorten the life of cloth fabrics
 Not suited for various industrial processes
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 Shorten life span of pipes (deposition and
scaling of salts)

REMOVAL OF HARDNESS
1. Boiling Temporary
Hardness
2. Addition of lime
3. Addition of sodium carbonates
4. Base exchange process
Permanent
1. Addition of Sodium carbonate Hardness
2. Base exchange process
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METHODS TO REMOVE HARDNESS
 Boiling : (Expensive , no large scale use)
Ca (HCO3)2 Ca CO3 + H2O + CO2
Insoluble Precipitate
Calcium carbonate
o Addition of Lime
Ca(OH)2 + Ca (HCO3)2 CaCO3 + H2O
Lime 16

ADDITION OF SODIUM CARBONATE (SODA ASH)
 Removes both temporary and permanent hardness
Na2 CO3 + Ca (HCO3)2 NaHCO3 + CaCO3
CaSO4 + Na2CO3 CaCO3 + Na2SO4
Base Exchange Process (large scale)
1. Sodium Permutit is used ( Na2Al2 Si2O H2O )
2. Exchange Na ions for Ca and Mg ions
3. Ca and Mg Permutit is formed .
4. Removes 100% hardness
5. Some raw water is added to protect against corrosive 17
action of 100% soft water

Fluoridation & Defluoridation of
water
 Is Naturally present in land
 Essential for dental and bone health
 Deficiency = dental caries
 Excess = Dental fluorosis ;
Skeletal fluorosis
 1 ppm is the optimum requirement in water
 Fluoridation = ++ Fluoride level
fluoride level.
 Defluoridation is the process of
 removing excess fL. Using 18
 Phosphate.

ASSIGNMENT WORD LIMIT : 250 WORDS
SUBMIT AT 9.30 AM (28TH JAN -12)
REWARD : ATTENDANCE
HAND WRITTEN
 Write Short Answers of following questions:
1. Differentiate between Break point Chlorination and Super-
chlorination
2. Name health hazards associated with using swimming pool.
3. Name Bacterial diseases related with drinking polluted water
4. Differentiate between shallow well and deep well
5. Name Hazards associated with surface water. 19

Thank you
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