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Water Water TechnologyTechnology
Sources of waterSources of water
o Rains, Rivers, Seas, glaciers, Springs, Rains, Rivers, Seas, glaciers, Springs, Lakes etc.Lakes etc.
o Rain water is the purest form of water.Rain water is the purest form of water.
o Water has different physical, chemical and Water has different physical, chemical and biological impurities which can cause biological impurities which can cause problems in both domestic and industrial problems in both domestic and industrial areas areas
Impurities in waterImpurities in water
o Physical Physical - Inorganic such as clay, sand- Inorganic such as clay, sand - Organic such as oil globules, vegetable/animal - Organic such as oil globules, vegetable/animal
mattermatter - Colloidal such as Fe(OH)- Colloidal such as Fe(OH)33, Complex proteins, , Complex proteins,
aminesamines
o Chemical Chemical
- Anions such as Cl- Anions such as Cl--, SO, SO442-2-, CO, CO33
2-2-,HCO,HCO33--, NO, NO33
-- of Ca & of Ca & MgMg
- Cations such as Ca- Cations such as Ca2+2+, Mg, Mg2+2+, Na, Na++, K, K++, Fe, Fe3+3+, Al, Al3+3+
- Dissolved gases such as O- Dissolved gases such as O22, N, N22, CO, CO22, H, H22S, NHS, NH33
o BiologicalBiological
- Microorganisms such as algae, fungi, bacteria- Microorganisms such as algae, fungi, bacteria (Pathogenic causing Malaria, diohhrrea, typhoid etc.)(Pathogenic causing Malaria, diohhrrea, typhoid etc.)
Hardness of waterHardness of watero Hardness of water is due to dissolved salts of mainly Hardness of water is due to dissolved salts of mainly
calcium and magnesium as well as iron and other heavy calcium and magnesium as well as iron and other heavy metals.metals.
o Hardness is two types:Hardness is two types:
a) Temporary :a) Temporary :
- Due to dissolved bicarbonates of calcium and magnesium and- Due to dissolved bicarbonates of calcium and magnesium and
carbonates of iron and other heavy metals.carbonates of iron and other heavy metals.
- Can be easily removed by boiling where CO- Can be easily removed by boiling where CO22 gas gets expelled gas gets expelled
removing the hardness.removing the hardness.
b) Permanent:b) Permanent:
- Due to dissolved chlorides and sulphates of calcium and - Due to dissolved chlorides and sulphates of calcium and magnesium.magnesium.
- Can be removed through zeolite, Lime-soda, ion-exchange - Can be removed through zeolite, Lime-soda, ion-exchange processes.processes.
Hardness of waterHardness of water o Water hardness can be identified when soap does not form lather. Water hardness can be identified when soap does not form lather.
o Problems of using hard water:Problems of using hard water:
a) Domestic:a) Domestic:
- wastage of fuel & time- wastage of fuel & time
- improper cleaning (wastage of soap) - improper cleaning (wastage of soap)
- health related issues ( Urinary infections, kidney stones) - health related issues ( Urinary infections, kidney stones)
b) Industrial:b) Industrial:
- Boiler troubles (scale, sludge, caustic embrittlement, - Boiler troubles (scale, sludge, caustic embrittlement,
priming and foaming)priming and foaming)
- wastage of fuel- wastage of fuel
- process related problems- process related problems
- problems in textile, sugar, paper, laundry, pharma industries- problems in textile, sugar, paper, laundry, pharma industries
Measurement of hardnessMeasurement of hardnesso Hardness of water is measured in parts per millions Hardness of water is measured in parts per millions
(ppm.) as calcium carbonate equivalents.(ppm.) as calcium carbonate equivalents.
o Reasons for expressing hardness in CaCOReasons for expressing hardness in CaCO3 3 equivalents:equivalents:
- its molecular weight is 100 ; equivalent weight is 50- its molecular weight is 100 ; equivalent weight is 50
- it is the most common impurity in water - it is the most common impurity in water
o Units of hardness:Units of hardness:
- parts per million in CaCO- parts per million in CaCO33 equivalents (1 mg/L is 1ppm.). equivalents (1 mg/L is 1ppm.).
- if 146 mg/L of MgSO- if 146 mg/L of MgSO44 is present in water, the hardness of is present in water, the hardness of
water is 146 ppm. as MgSOwater is 146 ppm. as MgSO44..
o When expressed in CaCOWhen expressed in CaCO33 equivalents, the formula for equivalents, the formula for conversion is:conversion is:
mass of hardness causing substancemass of hardness causing substance
Mol. Wt of hardness causing substance Mol. Wt of hardness causing substance
X 100 (mol. wt of CaCO3)
Expressing water hardnessExpressing water hardness
1. Ppm. measurement :1. Ppm. measurement : 1 part of CaCO1 part of CaCO3 3 equiv. in10 equiv. in1066 parts of water (1 mg/L). parts of water (1 mg/L).
2. Clark’s degree:2. Clark’s degree: 1 part of CaCO1 part of CaCO33 equiv. in 70,000 parts of water. equiv. in 70,000 parts of water.
3. French degree:3. French degree: 1 part of CaCO1 part of CaCO33 equiv. in 10 equiv. in 105 5 parts of water.parts of water.
* Conversion:* Conversion: 1ppm = 1 mg/L = 0.1Fr = 0.071ppm = 1 mg/L = 0.1Fr = 0.07ooCl = 0.02 meg/L Cl = 0.02 meg/L
Examples of hardness calculationsExamples of hardness calculations
A sample hard water contains,A sample hard water contains,
8.1 mg/L Ca(HCO8.1 mg/L Ca(HCO33))22 ; 7.5 mg/L Mg(HCO ; 7.5 mg/L Mg(HCO33))22; 13.6 mg/L CaSO; 13.6 mg/L CaSO44; ;
12.0 mg/L MgSO12.0 mg/L MgSO4 4 and 2.0 mg/L MgCl and 2.0 mg/L MgCl2.2.
To calculate the hardness and express in CaCOTo calculate the hardness and express in CaCO33 equivalents: equivalents:
ConstituentConstituent MultiplicatioMultiplication factorn factor
CaCOCaCO33 equivalents equivalents
Ca(HCOCa(HCO33))22= 8.1 mg/L = 8.1 mg/L 100/162100/162 8.1 x 100/162 = 5.0 mg/L8.1 x 100/162 = 5.0 mg/L
Mg(HCOMg(HCO33))2 2 = 7.5 mg/L= 7.5 mg/L 100/146100/146 7.5 x 100/146 = 5.14 mg/L7.5 x 100/146 = 5.14 mg/L
CaSOCaSO44= 13.6 mg/L= 13.6 mg/L 100/136100/136 13.6 x 100/136 = 5.0 mg/L13.6 x 100/136 = 5.0 mg/L
MgSOMgSO44= 12.0 mg/L= 12.0 mg/L 100/120100/120 12.0 x 100/120 =10.0 mg/L12.0 x 100/120 =10.0 mg/L
MgClMgCl22 = 2.0 mg/L = 2.0 mg/L 100/95100/95 2.0 x 100/95 = 2.11 mg/L2.0 x 100/95 = 2.11 mg/L
Disadvantages of hard waterDisadvantages of hard water1. Scale and Sludge formation:1. Scale and Sludge formation:
a) Sludges:a) Sludges:
b) Scales:b) Scales:
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o Soft, loose, slimy precipitates are sludgesSoft, loose, slimy precipitates are sludges
o Can be easily scrapped off with a wire brushCan be easily scrapped off with a wire brush
o Forms in comparatively colder portions of theForms in comparatively colder portions of the boiler such as bends etc. boiler such as bends etc.
o Formed because of MgCOFormed because of MgCO33, MgCl, MgCl22, CaCl, CaCl22, MgSO, MgSO44
Mg(OH)2,(more soluble in hot water)(more soluble in hot water)
o Dissolved salts deposit because of continuous evaporation of water concentration of salts increases
o These are hard and stick strongly to the walls
o Difficult to be removed even with a hammer and chisel.
o Formed because of CaCO3, CaSO4, CaSiO3, MgSiO3
Heat
Heat
Disadvantages of hard waterDisadvantages of hard water2. Priming and Foaming: 2. Priming and Foaming:
a) Foaming:a) Foaming:
o Foaming is the production of persistent foam or bubbles in boilers Foaming is the production of persistent foam or bubbles in boilers which do not break easily.which do not break easily.
o This is because of presence of oils which reduce the surface tension This is because of presence of oils which reduce the surface tension of water.of water.
o Can be avoided by adding anti-foaming agents like caster oil or Can be avoided by adding anti-foaming agents like caster oil or removing oil from the boiler feed water by adding sodium aluminate. removing oil from the boiler feed water by adding sodium aluminate.
b) Priming:b) Priming:
o Along with steam, some particles of water are carried (wet steam) Along with steam, some particles of water are carried (wet steam) which is called priming.which is called priming.
o This is because of large amounts of dissolved salts, high steam This is because of large amounts of dissolved salts, high steam velocities, sudden boiling, improper boiler design, sudden increase in velocities, sudden boiling, improper boiler design, sudden increase in steam production rate.steam production rate.
o Priming can be avoided by maintaining low water level in boilers, Priming can be avoided by maintaining low water level in boilers, avoiding rapid steam generation, efficient softening, installing avoiding rapid steam generation, efficient softening, installing mechanical steam purifiers.mechanical steam purifiers.
Disadvantages of hard waterDisadvantages of hard water3. Caustic embrittlement:3. Caustic embrittlement:
o Caused by using highly alkaline water in boilerCaused by using highly alkaline water in boiler
o When water is softened by lime-soda process, free NaWhen water is softened by lime-soda process, free Na22COCO33 is present is present
in softened water.in softened water.
o In high pressure boilers, this NaIn high pressure boilers, this Na22COCO33 decomposes to NaOH and CO decomposes to NaOH and CO22
NaNa22COCO3 3 + H+ H22O 2 NaOH + COO 2 NaOH + CO22
o This NaOH makes the water caustic.This NaOH makes the water caustic.
o This NaOH flows through minute cracks present in the boiler by This NaOH flows through minute cracks present in the boiler by
capillary action.capillary action.
o As water is boiling it evaporates and the conc. of NaOH increases.As water is boiling it evaporates and the conc. of NaOH increases.
o This caustic soda attacks the boiler and forms sodium ferroate.This caustic soda attacks the boiler and forms sodium ferroate.
o This makes the boiler parts brittle (embrittlement).This makes the boiler parts brittle (embrittlement).
Concentration cell formed during caustic Concentration cell formed during caustic embrittlementembrittlement
Caustic attack on boiler parts can be represented as:Caustic attack on boiler parts can be represented as:
Iron at Iron at Conc. NaOH Dil. NaOHConc. NaOH Dil. NaOH Iron at Iron at
rivettes, rivettes, soln. soln.soln. soln. Plane Plane bends, surfacesbends, surfacesJoints etc.Joints etc.
o The iron in contact with dil. NaOH becomes cathode and the iron in The iron in contact with dil. NaOH becomes cathode and the iron in contact with conc.NaOH becomes anode.contact with conc.NaOH becomes anode.
o The anodic part slowly dissolves and corrodes.The anodic part slowly dissolves and corrodes.
o Caustic embrittlement can be avoided by adding:Caustic embrittlement can be avoided by adding:
a) sodium phosphate (Softening agent)a) sodium phosphate (Softening agent)
b) tannin or lignin (Blocks hair line cracks)b) tannin or lignin (Blocks hair line cracks)
c) sodium sulphate (Blocks hair line cracks)c) sodium sulphate (Blocks hair line cracks)
+ _
Boiler corrosionBoiler corrosiono Decay of boiler material by chemical or electrochemical attack by Decay of boiler material by chemical or electrochemical attack by
surrounding environment.surrounding environment.o Reasons for boiler corrosion are:Reasons for boiler corrosion are:
a) Dissolved oxygena) Dissolved oxygen
b) Dissolved carbon dioxideb) Dissolved carbon dioxide c) Acids from dissolved salts c) Acids from dissolved salts
a)a) Dissolved oxygen (DO):Dissolved oxygen (DO):
2 Fe + H2 Fe + H22O + OO + O2 2 2 Fe(OH) 2 Fe(OH)22
2 Fe(OH)2 Fe(OH)22 + O + O2 2 2 Fe2 Fe22OO33.2H.2H22OO
o DO can be removed by adding calculated qty. of sodium sulphite DO can be removed by adding calculated qty. of sodium sulphite or hydrazine or sodium sulphide:or hydrazine or sodium sulphide:
2 Na2 Na22SOSO3 3 + O + O22 2 Na 2 Na22SOSO44
NN22HH44 + O + O22 N N22 + 2H + 2H22OO
NaNa22S + 2OS + 2O22 Na Na22SOSO44
o DO can be removed by mechanical aeration also. DO can be removed by mechanical aeration also.
Rust or corrosion
Boiler corrosionBoiler corrosionb) Dissolved COb) Dissolved CO22::
o Dissolved CODissolved CO22 forms carbonic acid which corrodes the boiler forms carbonic acid which corrodes the boiler slowly.slowly.
COCO22 + H + H22O HO H22COCO33
o COCO22 is removed by adding calculated quantity of ammonia: is removed by adding calculated quantity of ammonia:
2 NH2 NH44OH + COOH + CO22 (NH (NH44))22COCO33 + H + H22O O
o It is also removed by mechanical aeration along with oxygen.It is also removed by mechanical aeration along with oxygen.
c) Acids from dissolved salts:c) Acids from dissolved salts:o Dissolved magnesium salts hydrolyse to form acids:Dissolved magnesium salts hydrolyse to form acids:
MgClMgCl22 + 2 H + 2 H22O Mg(OH)O Mg(OH)22 + 2 HCl + 2 HCl
o This acid reacts with boiler and corrodes:This acid reacts with boiler and corrodes:
Fe + 2 HCl FeClFe + 2 HCl FeCl22 + H + H22
FeClFeCl2 2 + 2 H+ 2 H22O Fe(OH)O Fe(OH)2 2 + 2 HCl + 2 HCl
o Small quantity of magnesium salts will large amount of boiler Small quantity of magnesium salts will large amount of boiler corrosioncorrosion
Internal treatment methods for boiler Internal treatment methods for boiler feed waterfeed water
o Method is also called as Method is also called as Sequestration.Sequestration.o Ions are complexed to give more soluble salts.Ions are complexed to give more soluble salts.o Internal treatment is carried out to:Internal treatment is carried out to:
a) precipitate scale forming impurities into sludges which can bea) precipitate scale forming impurities into sludges which can be
removed by blow-down (Partial removal of hard water fromremoved by blow-down (Partial removal of hard water from
the bottom of the boiler) the bottom of the boiler)
b) convert scale forming impurities into compounds with higherb) convert scale forming impurities into compounds with higher
solubility so that they remain in solution.solubility so that they remain in solution.
o The methods are:The methods are:
a) Colloidal conditioning a) Colloidal conditioning
b) Phosphate conditioning b) Phosphate conditioning
c) Carbonate conditioning c) Carbonate conditioning
d) Calgon conditioning d) Calgon conditioning
e) Treatment with sodium aluminate (NaAlOe) Treatment with sodium aluminate (NaAlO22) )
Internal treatmentInternal treatmenta) Colloidal conditioning:a) Colloidal conditioning:o In low pressure boilers, scales are avoided by adding tannin, lignin, agar-In low pressure boilers, scales are avoided by adding tannin, lignin, agar-
agar.agar.
o These form a layer on the scale forming materials and loose precipitates These form a layer on the scale forming materials and loose precipitates are formed which can be easily removed by blow down.are formed which can be easily removed by blow down.
b) Phosphate conditioning:b) Phosphate conditioning:o In high pressure boilers, scales are avoided by adding sodium phosphate.In high pressure boilers, scales are avoided by adding sodium phosphate.
o This converts the scale forming impurities to soft sludge of calcium and This converts the scale forming impurities to soft sludge of calcium and magnesium phosphate which can be removed by blow down. magnesium phosphate which can be removed by blow down.
3 CaCl3 CaCl22 + 2 Na + 2 Na33POPO44 Ca Ca33(PO(PO44))22 + 6 NaCl + 6 NaCl
o The phosphates used are:The phosphates used are:
i) NaHi) NaH22POPO44 (acidic) – for highly alkaline water (acidic) – for highly alkaline water
ii) Naii) Na22HPOHPO44 (weakly alkaline) – for medium acidic/alkaline water (weakly alkaline) – for medium acidic/alkaline water
iii) Naiii) Na33POPO4 4 (alkaline) – for highly acidic water(alkaline) – for highly acidic water
Internal treatmentInternal treatmentc) Carbonate conditioning: c) Carbonate conditioning:
o In low pressure boilers, NaIn low pressure boilers, Na22COCO33 is added to the water to convert CaSO is added to the water to convert CaSO44 into into
CaCOCaCO33 so that CaSO so that CaSO44 scale formation is avoided. scale formation is avoided.
CaSOCaSO44 + Na + Na22COCO33 CaCOCaCO3 3 + Na + Na22SOSO44
o CaCOCaCO33 forms sludge and is removed by blow down. forms sludge and is removed by blow down.
d) Calgon conditioning:d) Calgon conditioning:
o Sodium hexa meta phosphate (NaPOSodium hexa meta phosphate (NaPO33))66 is Calgon. is Calgon.
o When added to water, it prevents formation of scales and sludges by When added to water, it prevents formation of scales and sludges by forming a soluble complex with CaSOforming a soluble complex with CaSO44..
Na[NaNa[Na44(PO(PO33))66] 2 Na] 2 Na+ + + [Na+ [Na44PP66OO1818]]2-2-
2 CaSO2 CaSO44 + [Na + [Na44PP66OO1818]]2- 2- [Ca[Ca22PP66OO1818]]2-2- + 2 Na + 2 Na22SOSO44 Soluble complex ion
Internal treatmentInternal treatment
e) Treatment with sodium aluminate(NaAlOe) Treatment with sodium aluminate(NaAlO22):):
o NaAlONaAlO2 2 hydrolyses with water to precipitate Al(OH)hydrolyses with water to precipitate Al(OH)33 : :
NaAlONaAlO22 + 2 H + 2 H22O NaOH + Al(OH)O NaOH + Al(OH)33
NaOH formed reacts with magnesium salts to yield Mg(OH)NaOH formed reacts with magnesium salts to yield Mg(OH)22
MgClMgCl22 + 2 NaOH Mg(OH) + 2 NaOH Mg(OH)22 + 2 NaCl + 2 NaCl
o The Mg and Al hydroxides trap suspended impurities including oil drops The Mg and Al hydroxides trap suspended impurities including oil drops and silica in the sludge.and silica in the sludge.
o This sludge is removed easily by blow down operation.This sludge is removed easily by blow down operation.
f) Electrical conditioning (using sealed electric bulbs), Radioactive f) Electrical conditioning (using sealed electric bulbs), Radioactive conditioning (using radioactive salt tablets) and conditioning (using radioactive salt tablets) and complexometric method (form stable and soluble complexes)complexometric method (form stable and soluble complexes)
are other internal treatment methods. are other internal treatment methods.
Gelatinous ppt.
Water Softening methodsWater Softening methods1. Lime soda1. Lime soda
a) Batch process a) Batch process
b) continuous process b) continuous process
- Cold lime-soda- Cold lime-soda
- Hot lime-soda- Hot lime-soda
2. Zeolite (permutit process) 2. Zeolite (permutit process)
3. Ion-exchange 3. Ion-exchange
4. Mixed bed ion-exchange4. Mixed bed ion-exchange
Reactions of lime and sodaReactions of lime and sodaa. Reaction of permanent calcium:a. Reaction of permanent calcium:
CaCa2+2+ + Na + Na22COCO33 CaCO CaCO33 + 2Na + 2Na++
b. Reactions of permanent magnesium:b. Reactions of permanent magnesium:
MgMg2+2+ + Ca(OH) + Ca(OH)22 Ca Ca2+2+ + Mg(OH) + Mg(OH)22
CaCa2+ 2+ + Na+ Na22COCO3 3 CaCOCaCO33 + 2Na + 2Na++
c. Reaction of HCOc. Reaction of HCO33-- (ex-Na (ex-Na22COCO33):):
2 HCO2 HCO3-3- + Ca(OH) + Ca(OH)22 CaCO CaCO33 + H + H22O + COO + CO332-2-
d. Reaction of Ca(HCOd. Reaction of Ca(HCO33))22 : :
Ca(HCOCa(HCO33))22 + Ca(OH) + Ca(OH)22 2 CaCO 2 CaCO33 + 2 H + 2 H22OO
e.e. Reaction of Mg(HCOReaction of Mg(HCO33))22 : :
Mg(HCOMg(HCO33))22 + Ca(OH) + Ca(OH)22 2 MgCO 2 MgCO33 + 2 H + 2 H22O + Mg(OH)O + Mg(OH)22
Reactions of lime and sodaReactions of lime and sodaf. Reaction of COf. Reaction of CO22::
COCO22 + Ca(OH) + Ca(OH)22 CaCO CaCO3 3 + H + H22OO
g. Reaction of Hg. Reaction of H++::
2 H2 H++ + Ca(OH) + Ca(OH)2 2 CaCa2+2+ + 2 H + 2 H22O O
CaCa2+ 2+ + Na+ Na22COCO33 CaCO CaCO33 + 2 Na + 2 Na++
h. Reactions of coagulants:h. Reactions of coagulants:
i)i) Reaction of FeSOReaction of FeSO44::
FeFe2+2+ + Ca(OH) + Ca(OH)22 Fe(OH) Fe(OH)22 + Ca + Ca2+2+
Fe(OH)Fe(OH)2 2 + H+ H22O + OO + O2 2 2 Fe(OH) 2 Fe(OH)3 3
CaCa2+2+ + Na + Na22COCO3 3 CaCOCaCO33 + 2 Na + 2 Na
ii) Reactions of Aluminium sulphate (Al2(SO4)3 :
2 Al3+ + 3 Ca(OH)2 2 Al(OH)3 + 3 Ca2+
3 Ca2+ + 3 Na2CO3 3 CaCO3 + 6 Na+
iii) Reactions of sodium aluminate (NaAlO2):
NaAlO2 + H2O Al(OH)3 + NaOH
A. Lime [Ca(OH)2]requirement :
74 Temp. CaTemp. Ca2+2+ + 2 temp. Mg + 2 temp. Mg2+2+ + Perm(Mg + Perm(Mg2+2+ + Al+ Al3+3+ + Fe + Fe2+2+) ) + + COCO22 + H + H++ + HCO3
- - NaAlO2
B. Soda[Na2CO3] requirement :
106 Perm. (Ca2+ + Mg2+ Fe2+ + Al3+) + H+ - HCO3-
{ 100 {
{ {
100
o Hot lime-soda process consists of three parts:
a) Reaction tank to mix all ingredients
b) Conical sedimentation vessel where the sludge settles down
c) Sand filter where sludge is completely removed
Advantages of hot lime-soda processAdvantages of hot lime-soda process
o The precipitation reaction is almost complete
o Reaction takes place faster
o Sludge settles down rapidly; No coagulant is needed
o Dissolved gases (which may cause corrosion) are removed
o Viscosity of soft water is lower, hence filtered easily
o Residual hardness is low compared to cold lime-soda
process
Advantages of Lime – soda process:
1. Economical2. Process improves the corrosion resistance of water3. Mineral content of water is reduced 4. pH of water raises thus reducing content of pathogenic
bacteria5. No skilled labour is required
Disadvantages of Lime – soda process:1. Huge amount of sludge is formed and its disposal is
difficult2. Due to residual hardness, water is not suitable for high
pressure boilers
Permutit or Zeolite ProcessPermutit or Zeolite Processo Zeolite is hydrated sodium aluminium silicate having a general Zeolite is hydrated sodium aluminium silicate having a general
formula, Naformula, Na22OAlOAl22OO33.xSiO.xSiO22.yH.yH22O.O.
o It exchanges NaIt exchanges Na++ ions for Ca ions for Ca2+2+ and Mg and Mg2+ 2+ ions.ions.
o Common Zeolite is NaCommon Zeolite is Na22OAlOAl22OO33.3SiO.3SiO22.2H.2H22O known as O known as natrolith.natrolith.
o Other gluconites, green sand (iron potassium phyllosilicate with Other gluconites, green sand (iron potassium phyllosilicate with
characteristic green colour, a mineral containing Glauconite)etc. characteristic green colour, a mineral containing Glauconite)etc.
are used for water softening.are used for water softening.
o Artificial zeolite used for water softening is Artificial zeolite used for water softening is Permutit.Permutit.
o These are porous, glassy particles having higher softening These are porous, glassy particles having higher softening
capacity compared to green sand.capacity compared to green sand.
o They are prepared by heating china clay (hydrated aluminium They are prepared by heating china clay (hydrated aluminium
silicate), feldspar (KAlSisilicate), feldspar (KAlSi33OO88-NaAlSi-NaAlSi33OO88 – CaAl – CaAl22SiSi22OO88) are a group of ) are a group of
rock-forming tectosilicate minerals which make up as much as rock-forming tectosilicate minerals which make up as much as
60% of the earth’s crust) and soda ash (Na60% of the earth’s crust) and soda ash (Na22COCO33))
Zeolite processZeolite process
o Method of softening:Method of softening:
NaNa22Ze + Ca(HCOZe + Ca(HCO33))22 2 NaHCO 2 NaHCO33 + CaZe + CaZe NaNa22Ze + Mg(HCOZe + Mg(HCO33))22 2 NaHCO 2 NaHCO33 + MgZe + MgZe
NaNa22Ze + CaSOZe + CaSO4 4 2 Na 2 Na22SOSO44 + CaZe + CaZe
NaNa22Ze + CaClZe + CaCl2 2 2 NaCl + CaZe 2 NaCl + CaZe
o Regeneration of Zeolite:Regeneration of Zeolite: CaZe (or) MgZe + 2 NaCl NaCaZe (or) MgZe + 2 NaCl Na22Ze + CaClZe + CaCl22 or MgCl or MgCl22
Brine solutionBrine solution
Zeolite ProcessZeolite Processo Advantages:Advantages:
o Residual hardness of water is about 10 ppm onlyo Equipment is small and easy to handleo Time required for softening of water is smallo No sludge formation and the process is cleano Zeolite can be regenerated easily using brine solutiono Any type of hardness can be removed without any
modifications to the process
o Disadvantages:Disadvantages:o Coloured water or water containing suspended impurities
cannot be used without filtration
o Water containing acidic pH cannot be used for softening since acid will destroy zeolite.
Ion-Exchange ProcessIon-Exchange Process o Ion-exchange resins are cross linked long chain polymers with microporous structureo Functional groups present are responsible for ion-exchange properties
o Acidic functional groups (-COOH, -SO3H etc.) exchange H+ for
cations &
o Basic functional groups (-NH2, =NH etc.) exchange OH- for
anions.A. Cation-exchange Resins(RH+): - Styrene divinyl benzene copolymers
- When sulphonated, capable of exchange H+
Ion-Exchange ProcessIon-Exchange ProcessB. Anion-exchange resins (R’OH):
- Styrene divinyl benzene copolymers or amine formaldehyde copolymers with NH2, QN+, QP+, QS+, groups.
- On alkali treatment, capable of exchange of OH-
Ion-Exchange ProcessIon-Exchange Process The Process of Ion-exchange is:
2 RH+ + Ca2+/Mg2+ R2Ca2+/R2Mg2+ + 2 H+ (Cation exchange)
R’OH- + Cl- R’+ Cl- + OH- (anion exchange)
2 R’OH- + SO42- R’2 SO4
2- + 2 OH- (anion exchange)
2 R’OH- + CO32- R’2 CO3
2- + 2 OH- (anion exchange)
Finally,H+ + OH- H2O
Regeneration of exhausted resins:
Saturated resins are regenerated:
R2Ca2+/R2Mg2+ + 2H+ 2 RH+ + Ca2+/Mg2+ (cation) (Stong acid) (washings) R’2 SO4
2- + 2 OH- 2 R’OH- + SO42- (Strong
base) (washings)
Ion-exchange processIon-exchange process
Note: Hard water should be first passed through the cation exchanger and then Anion exchanger to avoid hydroxides of Ca2+ and Mg2+ getting formed
Mixed bed ion-exchangerMixed bed ion-exchanger
Deminaralised Deminaralised waterwater
Mixed ionizer bed
Mixed ionizerMixed ionizer bedbed
Exhausted Exhausted mixed mixed
ionizer bedionizer bed
Cation exchangerCation exchanger(higher density)(higher density)
Anion exchangerAnion exchanger(low density)(low density)
NaOHNaOH
HH22SOSO44
Washings to Washings to sinksink
Comp.Comp.airair
Backwash Backwash waterwater
Raw waterRaw waterinletinlet
o Contains intimate mixture of cation and anion exchangersContains intimate mixture of cation and anion exchangers
o Water is in contact for a no. of times with the two exchangers alternativelyWater is in contact for a no. of times with the two exchangers alternatively
Advantages & Disadvantages of Advantages & Disadvantages of ion-exchange procession-exchange process
o Advantages:Advantages:
- Can be used for highly acid and highly alkaline water- Can be used for highly acid and highly alkaline water
- Residual hardness of water is as low as 2 ppm.- Residual hardness of water is as low as 2 ppm.
- Very good for treating water for high pressure boilers- Very good for treating water for high pressure boilers
o Disadvantages:Disadvantages:
- Expensive equipment and chemicals- Expensive equipment and chemicals
- Turbidity of water should be < 10 ppm. Otherwise output will- Turbidity of water should be < 10 ppm. Otherwise output will
reduce; turbidity needs to be coagulated before treatment.reduce; turbidity needs to be coagulated before treatment.
- Needs skilled labour- Needs skilled labour
Treatment of water for municipal supplyTreatment of water for municipal supply
o Drinking or potable water should be safe to drink Drinking or potable water should be safe to drink and should satisfy the following requirements:and should satisfy the following requirements:
a)a) Sparklingly clean and odourlessSparklingly clean and odourless
b)b) Pleasant in tastePleasant in taste
c)c) Perfectly coolPerfectly cool
d)d) Turbidity should not exceed 10 ppm.Turbidity should not exceed 10 ppm.
e)e) Free from objectionable minerals like Pb, As, Cr and MnFree from objectionable minerals like Pb, As, Cr and Mn
f)f) Free from dissolved gases like HFree from dissolved gases like H22SS
g)g) Alkalinity should not be too high (pH should be around 8.0)Alkalinity should not be too high (pH should be around 8.0)
h)h) Should be reasonably softShould be reasonably soft
i)i) TDS should be less than 500 ppmTDS should be less than 500 ppm
j)j) Free from pathogenic microorganismsFree from pathogenic microorganisms
Purification of water for domestic supplyPurification of water for domestic supplyThe following are the steps of purification:The following are the steps of purification:
A. Removal of suspended impurities:A. Removal of suspended impurities:
a) Screening:a) Screening: Floating matter is filter through large screens having large no.Floating matter is filter through large screens having large no.
of holes.of holes.
b) Sedimentation:b) Sedimentation: To remove suspended particles, water is allowed toTo remove suspended particles, water is allowed to
stand in big tanks where suspended matter settles down in thestand in big tanks where suspended matter settles down in the
bottom. bottom.
Supernatant water is pumped off.Supernatant water is pumped off.
If water contains colloidial and fine clay particles, a coagulant is addedIf water contains colloidial and fine clay particles, a coagulant is added
during sedimentation and the process is called during sedimentation and the process is called “Sedimentation with“Sedimentation with
coagulation”coagulation” . .
Coagulant such as alum or ferrous sulphate will form insoluble gelatinousCoagulant such as alum or ferrous sulphate will form insoluble gelatinous
ppts. and settle them down in the bottom.ppts. and settle them down in the bottom.
Alum (KAlum (K22SOSO44.Al.Al22(SO(SO44))33.24H.24H22O, Sodium Aluminate (NaAlOO, Sodium Aluminate (NaAlO22) and Ferrous) and Ferrous
sulphate (FeSOsulphate (FeSO44.7H.7H22O) are normally used coagulants. O) are normally used coagulants.
Purification of water for domestic supplyPurification of water for domestic supplye) Filtration:e) Filtration: Filtration is a process of removing colloidal matter, most of the Filtration is a process of removing colloidal matter, most of the microorganisms etc. microorganisms etc.
Filtration is carried out using Sand Filter bed containing coarse andFiltration is carried out using Sand Filter bed containing coarse and fine sand layers through which water is passed.fine sand layers through which water is passed.
The irregular pores in the sand filter hold the sedimented materialsThe irregular pores in the sand filter hold the sedimented materials etc., allowing water without these impurities to pass through.etc., allowing water without these impurities to pass through.
f) Removal of microorganisms: f) Removal of microorganisms: The process of destroying pathogenicThe process of destroying pathogenic microorganisms etc., from water is called microorganisms etc., from water is called “Disinfection”.“Disinfection”.
Disinfection can be carried out by:Disinfection can be carried out by:
1.1. By boiling:By boiling: Boiling for 15 minutes to kill all microorganisms. This cannot Boiling for 15 minutes to kill all microorganisms. This cannot prevent growth of microrganisms again.prevent growth of microrganisms again.
2.2. By adding bleaching powder:By adding bleaching powder:1 kg. of bleaching powder is added per 1 kg. of bleaching powder is added per 1000L of water1000L of water and allowed to stand for several hours.and allowed to stand for several hours.
CaOClCaOCl22 + H + H22OO Ca(OH)Ca(OH)22 + Cl + Cl22
ClCl22 + H + H22O HCl + HOCl (Hyporhlorous acid)O HCl + HOCl (Hyporhlorous acid)
Microorganisms + HOCl microorganisms are killed Microorganisms + HOCl microorganisms are killed
Drawbacks:Drawbacks: Bleaching powder introduced calcium to water increasing the hardness.Bleaching powder introduced calcium to water increasing the hardness.
Bleaching powder deteriorates on storage for a long timeBleaching powder deteriorates on storage for a long time
Excess beaching powder will gives bad taste and smell to the water. Excess beaching powder will gives bad taste and smell to the water.
3. By Chlorination: 3. By Chlorination: Chlorine (gas or concentrated liquid) produces Chlorine (gas or concentrated liquid) produces hypochlorous acid which destroys the microorganismshypochlorous acid which destroys the microorganisms
ClCl22 + H + H22O HOCl + HClO HOCl + HCl
HOCl HHOCl H++ + OCl + OCl-- (Hypochlorite ion) (Hypochlorite ion)
This HOCl inactivates the enzymes of microorganisms. This HOCl inactivates the enzymes of microorganisms.
By Liquid chlorine: By Liquid chlorine: Liquid chlorine is found to be most effective and most Liquid chlorine is found to be most effective and most widely used disinfectant throughout the world.widely used disinfectant throughout the world.
A Chlorinator is used for adding adequate quantity of chlorine so that the A Chlorinator is used for adding adequate quantity of chlorine so that the residual chlorine is 0.1 to 0.2 ppm. in treated water.residual chlorine is 0.1 to 0.2 ppm. in treated water.
While chlorination,While chlorination,
time of contact (depends on no. of microorganisms)time of contact (depends on no. of microorganisms)
temperature of water (higher temperature will kill microrganisms faster)temperature of water (higher temperature will kill microrganisms faster)
pH of water (lower pH of water, say 5-6.5, needs lower contact time) pH of water (lower pH of water, say 5-6.5, needs lower contact time)
Diagram of chlorinatorDiagram of chlorinator
Baffle platesBaffle plates
High towerHigh tower
Concentrated Concentrated chlorine solutionchlorine solution
Raw water inlet
Sterilized water outletSterilized water outlet
Chlorination of waterChlorination of water Advantages of chlorine:Advantages of chlorine:
o Effective and economicalEffective and economicalo Needs very little storage spaceNeeds very little storage spaceo Chlorine is stable and does not deteriorateChlorine is stable and does not deteriorateo Can be used at low and high temperaturesCan be used at low and high temperatureso Does not introduce any salt impurities to waterDoes not introduce any salt impurities to water
Disadvantages of chlorine:Disadvantages of chlorine:
o Excess of chlorine produces characteristic smell and tasteExcess of chlorine produces characteristic smell and tasteo It also causes irritation to mucus membraneIt also causes irritation to mucus membraneo Residual chlorine should not exceed 0.1-0.2 ppm.Residual chlorine should not exceed 0.1-0.2 ppm.o It is most effective below pH 6.5 and not very effective at higher It is most effective below pH 6.5 and not very effective at higher
pH.pH.
Break-point chlorinationBreak-point chlorination
Applied dosage of chlorineApplied dosage of chlorine
Oxidn. Of Oxidn. Of reducing reducing compounds compounds by chlorineby chlorine
Formation of Formation of chloro-organic chloro-organic compounds and compounds and chloramineschloramines
DestructionDestructionof chloro-of chloro-organic organic compounds compounds and and chloramineschloramines
Free residual Free residual chlorinechlorine
aa
bb
cc
dd
Resi
dual ch
lori
ne
Resi
dual ch
lori
ne
Advantages of break point chlorinationAdvantages of break point chlorination1.1. Oxidises the organic compounds, ammonia and other reducing Oxidises the organic compounds, ammonia and other reducing
compounds completelycompounds completely
2.2. Removes colour from waterRemoves colour from water
3.3. Destroys 100% of the microorganismsDestroys 100% of the microorganisms
4.4. Removes bad smell and taste of waterRemoves bad smell and taste of water
Dechlorination:Dechlorination:
Excess chlorine beyond the break-point produces bad taste and smell. Excess chlorine beyond the break-point produces bad taste and smell.
Excess chlorine can be removed by:Excess chlorine can be removed by:
a)a) Passing the excess chlorinated water through a bed of carbonPassing the excess chlorinated water through a bed of carbon
b)b) Adding activated carbon and allowing a short reaction timeAdding activated carbon and allowing a short reaction time
c)c) Adding small quantities of sulphur dioxide or sodium sulphite or Adding small quantities of sulphur dioxide or sodium sulphite or
sodium thiosulphate:sodium thiosulphate:
SOSO22 + Cl + Cl22 + 2H + 2H22O HO H22SOSO44 + 2 HCl + 2 HCl
NaNa22SOSO33 + Cl + Cl22 + 2H + 2H22O NaO Na22SOSO44 + 2 HCl + 2 HCl
NaNa22SS22OO33 + Cl + Cl22 + H + H22O NaO Na22SOSO44 + 2 HCl + S + 2 HCl + S
Disinfection of waterDisinfection of water 4. By using chloramine (ClNH4. By using chloramine (ClNH22):):o When chlorine are added in the ratio of 2:1, chloramine is formed.When chlorine are added in the ratio of 2:1, chloramine is formed.
ClCl22 + NH + NH22 ClNH ClNH22 + HCl + HCl
o Chloramine is more reactive than chlorine alone and is a better bactericidal agent Chloramine is more reactive than chlorine alone and is a better bactericidal agent than chlorine.than chlorine.
ClNHClNH2 2 + H+ H22O HOCl + NHO HOCl + NH33
o Chloramine does not produce any bad smell and also adds good taste to water.Chloramine does not produce any bad smell and also adds good taste to water.
5. Disinfection by Ozone:5. Disinfection by Ozone:
o Ozone gas is a very good disinfecting agent. Ozone gas is a very good disinfecting agent. o Zone is unstable and breaks down to give nascent oxygen.Zone is unstable and breaks down to give nascent oxygen.
OO33 O O22 + [O] + [O]
o This nascent oxygen is a powerful disinfecting agent and kills all the microorganisms.This nascent oxygen is a powerful disinfecting agent and kills all the microorganisms.o The disadvantage is that the method is very expensive.The disadvantage is that the method is very expensive.o Advantage is that it removes colour, smell and taste without giving any residue.Advantage is that it removes colour, smell and taste without giving any residue.
Diagram of Ozone sterilizerDiagram of Ozone sterilizer
Contact tankContact tank
Ozone inletOzone inletRaw water Raw water
inletinlet
Disinfected Disinfected water outletwater outlet
Flow diagram of municipal water treatmentFlow diagram of municipal water treatment Raw Raw waterwater
Mixing Mixing tanktank
Sand filterSand filter
Fine sandFine sand
Coarse sandCoarse sand
gravelgravel
Liquid Liquid chlorinechlorine
To To SupplySupply
AlumAlum
Desalination of brackish waterDesalination of brackish watero Water containing dissolved salts with a peculiar salty (brackish)Water containing dissolved salts with a peculiar salty (brackish) taste is brackish watertaste is brackish water
o The process of removing common salt from water is desalinationThe process of removing common salt from water is desalination
The methods of desalination are:The methods of desalination are:1.1. Electrodialysis Electrodialysis 2.2. Reverse osmosis Reverse osmosis
1.1. Electrodialysis:Electrodialysis:o Electrodialysis consists of a large container with two membrane Electrodialysis consists of a large container with two membrane
separators, one permeable to positive ions and the other separators, one permeable to positive ions and the other permeable to negative ions. permeable to negative ions.
o In the outer compartments anode and cathode are arranged to In the outer compartments anode and cathode are arranged to pass DC Voltage.pass DC Voltage.
o When DC voltage/current is passed through the cell, NaWhen DC voltage/current is passed through the cell, Na++ will move will move towards cathode and Cltowards cathode and Cl-- will move towards anode through the will move towards anode through the membrane.membrane.
o Hence, the concentration of salt decreases in the middle Hence, the concentration of salt decreases in the middle compartment and increases in the side compartments. compartment and increases in the side compartments.
o Water from the middle compartment is collected and this water is Water from the middle compartment is collected and this water is desalinated water. desalinated water.
Electrodialysis diagramElectrodialysis diagram
For efficient separation, ion-selective membranes are used which For efficient separation, ion-selective membranes are used which selectively allow cations or anions to pass through them.selectively allow cations or anions to pass through them.
Electrodialysis cellElectrodialysis cell
o Electrodialysis cell consists Electrodialysis cell consists of Large number of pairs ofof Large number of pairs of
rigid Plastic membranes.rigid Plastic membranes.
o Saline water at a pressure Saline water at a pressure of 5-6 kg/cmof 5-6 kg/cm22 is passed is passed
through the membrane through the membrane pairs.pairs.
o DC current is applied DC current is applied perpendicular to the perpendicular to the
direction of water flow. direction of water flow.
Advantages are:Advantages are: 1.1. Unit is compact and Unit is compact and
installation is economicalinstallation is economical
2.2. Best suited if electricity is Best suited if electricity is available. available.
Reverse osmosisReverse osmosis
oWhen two solutions of unequal concentrations are separated by a Semipermeable membrane, solvent will flow from lower conc. to higher conc.
oThis phenomenon can be reversed (solvent flow reversed) by applying hydrostatic pressure on the concentrated side
oIn reverse osmosis, pressure of 15-40 kg/cm2 is applied to sea water.
oThe water gets forced through the semipermeable membrane leaving behind the dissolved solids.
Advantages of Advantages of ReverseReverse OsmosisOsmosis
o Advantage is in removing ionic, non-ionic, colloidal and high molecular wt. organic matter.
o It removes colloidal silica (which is not removed during demineralisation)
o Cost is only the replacement cost of membranes (life is 2 years)
o Membrane replacement is fast and hence uninterrupted water supply can be ensured
o Because of the above reasons this process is being adopted for converting sea water into potable water and for high pressure boilers.
Estimation of water hardnessEstimation of water hardness1. EDTA method1. EDTA method2. Alkali titration method2. Alkali titration method
1. EDTA method:1. EDTA method:o Ethylene diamine tetraacetic acid disodium salt (EDTA disodium salt) isEthylene diamine tetraacetic acid disodium salt (EDTA disodium salt) is used as a strong complexing agent with Caused as a strong complexing agent with Ca2+2+ and Mg and Mg2+2+ in hard water. in hard water. o The structure of EDTA disodium salt is:The structure of EDTA disodium salt is:
N CHN CH2 2 CHCH2 2 NN
o Initially, CaInitially, Ca2+2+ and Mg and Mg2+2+ are treated with Eriochrome black T (EBT) indicator are treated with Eriochrome black T (EBT) indicator using ammonia buffer (to maintain pH between 9-10) to get an unstable using ammonia buffer (to maintain pH between 9-10) to get an unstable complex of Cacomplex of Ca2+2+ and Mg and Mg2+2+ formed with EBT. formed with EBT.
CaCa2+2+/Mg/Mg2+2+ + EBT Ca + EBT Ca2+2+/Mg/Mg2+2+ EBT EBT (unstable complex – wine red) (unstable complex – wine red)
CHCH22COOHCOOH
HOOCHHOOCH22CC CHCH22COONaCOONa
NaOOCHNaOOCH22CC
pH 9-10
EDTA method of water hardness estimationEDTA method of water hardness estimationo After titration with EDTA, EBT gets replaced with EDTA since EDTA forms a After titration with EDTA, EBT gets replaced with EDTA since EDTA forms a
stronger complex with the metal ions.stronger complex with the metal ions.
o This is indicated by the formation of a This is indicated by the formation of a steel bluesteel blue coloured complex. coloured complex.
CaCa2+2+/Mg/Mg2+2+ EBT + EDTA Ca EBT + EDTA Ca2+2+/Mg/Mg2+2+ EDTA + EBT EDTA + EBT
(Stable complex - Steel blue) (Stable complex - Steel blue)
Procedure:Procedure:
o First EDTA Solution is standardized using standard hard water (1 mg/ml of First EDTA Solution is standardized using standard hard water (1 mg/ml of
CaCOCaCO33 equivalents is prepared as standard hard water). equivalents is prepared as standard hard water).
o For this, first known aliquot of Standard hard water is taken and 10-15 mL of For this, first known aliquot of Standard hard water is taken and 10-15 mL of
ammonia buffer is added to bring the pH between 9-10.ammonia buffer is added to bring the pH between 9-10.
o Then a few drops of EBT solution is added to form the unstable complex Then a few drops of EBT solution is added to form the unstable complex
giving wine red colour.giving wine red colour.
o This solution is titrated with the EDTA solution till the solution turns to steel This solution is titrated with the EDTA solution till the solution turns to steel
blue indicating the formation of stable EDTA-Metal ion complex.blue indicating the formation of stable EDTA-Metal ion complex.
o This volume of EDTA is noted as VThis volume of EDTA is noted as V11..
o The above procedure is repeated with sample hard water of unknown The above procedure is repeated with sample hard water of unknown
hardness.hardness.
o Volume of EDTA is noted as VVolume of EDTA is noted as V22..
pH 9-10
EDTA method of water hardness estimationEDTA method of water hardness estimationo Then sample hard water of 250 mL is taken and evaporated to a volume of Then sample hard water of 250 mL is taken and evaporated to a volume of
50mL when the temporary hard salts settle down.50mL when the temporary hard salts settle down.
o The solution is filtered and washed thoroughly and made up again to 250mL.The solution is filtered and washed thoroughly and made up again to 250mL.
o From this solution, 50 mL is pipetted out and titrated in similar manner as From this solution, 50 mL is pipetted out and titrated in similar manner as
done with standard hard water.done with standard hard water.
o Volume of EDTA is noted as VVolume of EDTA is noted as V33..
Calculations: Calculations:
a) Total hardness:a) Total hardness:
VV11mL of EDTA is consumed by 50 mL of std. hard watermL of EDTA is consumed by 50 mL of std. hard water
VV11mL of EDTA = 50 mg of CaCOmL of EDTA = 50 mg of CaCO33
1 mL of EDTA = 50/V1 mL of EDTA = 50/V11 mg of CaCO mg of CaCO33
EDTA consumed by sample hard water = VEDTA consumed by sample hard water = V22 mL mL
So, VSo, V22 mL of EDTA = 50/V mL of EDTA = 50/V11 x V x V22 mg of CaCO mg of CaCO33
Hence, 50 mL of sample hard water contains 50/VHence, 50 mL of sample hard water contains 50/V11 x V x V22 mg of CaCO mg of CaCO33
Therefore, 1000mL of sample hard water = 50/VTherefore, 1000mL of sample hard water = 50/V11 x V x V2 2 x 1000 mg/L x 1000 mg/L
i.e. Total hardness of sample hard water = Vi.e. Total hardness of sample hard water = V22/V/V11 x 1000 mg of CaCO x 1000 mg of CaCO33 (ppm.) (ppm.)
EDTA method of water hardness estimationEDTA method of water hardness estimationPermanent hardness:Permanent hardness:
50 mL of sample hard water after removing temporary hardness consumed50 mL of sample hard water after removing temporary hardness consumed
VV3 3 mL of mL of EDTA.EDTA.
1 mL of EDTA = 50/V1 mL of EDTA = 50/V11 mg of CaCO mg of CaCO33
Therefore,Therefore, V V33 mL of EDTA = 50/V mL of EDTA = 50/V11 x V x V33 mg of CaCO mg of CaCO33
50 mL of sample hardwater after boiling contained 50/V50 mL of sample hardwater after boiling contained 50/V11 x V x V33 mg of CaCO mg of CaCO33
Therefore, 1000 mL of sample hard water containsTherefore, 1000 mL of sample hard water contains
Permanent hardness = Permanent hardness =
5050 VV33
VV11 5050
xx XX 1000mg/L1000mg/L
VV33
VV11
X 1000 mg/L of CaCOX 1000 mg/L of CaCO33 (ppm.) (ppm.)
EDTA method of water hardness estimationEDTA method of water hardness estimation
Temporary hardness:Temporary hardness:
Temporary hardness = Total hardness – permanent hardnessTemporary hardness = Total hardness – permanent hardness
VV22 V V33
V1 V1 V1 V1
= = 1000 X1000 X
= = 1000 X1000 X
X 1000 X 1000 X 1000X 1000 {{ {{{{ {{VV22
[[[[[[[[
VV11
{{ {{{{VV22
[[[[[[[[
VV11
{{
ppm.ppm.
VV22 – V – V33
VV11
{{ {{
ppm.ppm.
