WATER CHEMISTRY & WATER CHEMISTRY & APPLICATIONS IN WATER APPLICATIONS IN WATER TREATMENT TREATMENT 1. 1. WATER SOURCES WATER SOURCES 2. 2. WATER TREATMENT PROCESSES WATER TREATMENT PROCESSES 3. 3. WATER QUALITY REQUIREMENTS FOR WATER QUALITY REQUIREMENTS FOR PROCESS INDUSTRIES PROCESS INDUSTRIES
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WATER CHEMISTRY & WATER CHEMISTRY & APPLICATIONS IN WATER APPLICATIONS IN WATER
TREATMENTTREATMENT 1.1. WATER SOURCESWATER SOURCES
2.2. WATER TREATMENT PROCESSESWATER TREATMENT PROCESSES
3.3. WATER QUALITY REQUIREMENTS FOR WATER QUALITY REQUIREMENTS FOR PROCESS INDUSTRIESPROCESS INDUSTRIES
WATER SOURCESWATER SOURCES
1.1.WELL WATERWELL WATER a. SHALLOW WELLSa. SHALLOW WELLS b. DEEP WELLSb. DEEP WELLS
2.2.SURFACE WATERSURFACE WATER a. RIVERa. RIVER b. LAKEb. LAKE
3.3.SEA WATERSEA WATER a. OPEN SEA INTAKEa. OPEN SEA INTAKE b. BEACH WELLSb. BEACH WELLS
WATER CHEMISTRYWATER CHEMISTRY
Water Water Composition – Suspended ImpuritiesComposition – Suspended Impurities
Suspended SolidsSuspended Solids
- Organics Compounds- Organics Compounds - Iron- Iron
- Silt- Silt- Bacteria- Bacteria
WATER CHEMISTRYWATER CHEMISTRY Water Composition – Dissolved ImpuritiesWater Composition – Dissolved Impurities
CationsCations- Calcium (Ca)- Calcium (Ca)
- Magnesium (Mg)- Magnesium (Mg) - Sodium (Na)- Sodium (Na) - Potassium (K)- Potassium (K)
- Barium (Ba)- Barium (Ba)- Strontium (Sr)- Strontium (Sr)
WATER CHEMISTRYWATER CHEMISTRY
Anions Anions - Carbonate (CO3)- Carbonate (CO3)- Bicarbonate (HCO3)- Bicarbonate (HCO3)- Sulphate (SO4)- Sulphate (SO4)- Nitrate (NO3)- Nitrate (NO3)- Nitrite (NO2)- Nitrite (NO2)- Chloride (Cl)- Chloride (Cl)- Floride (F)- Floride (F)- Silica (Si)- Silica (Si)
WATER CLASSIFICATIONS BASED WATER CLASSIFICATIONS BASED ON TOTAL DISSOLVED SOLIDS ON TOTAL DISSOLVED SOLIDS (TDS)(TDS)
Tap Water Tap Water < 1000 ppm < 1000 ppm BRACKISH BRACKISH 1000-5000 ppm1000-5000 ppmHIGLLY BRACKISH 5000-15000 ppmHIGLLY BRACKISH 5000-15000 ppmSALINE SALINE 15000-30000 ppm15000-30000 ppmSEA WATER SEA WATER 30000-40000 ppm30000-40000 ppmBRINE BRINE 40000-300000 ppm40000-300000 ppm
WATER TREATMENT PROCESSESWATER TREATMENT PROCESSES
• Clarification / SedimentationClarification / Sedimentation• FilterationFilteration• Lime Soda SofteningLime Soda Softening• Softening Through Ion ExchangeSoftening Through Ion Exchange• DemineralizationDemineralization• De-AlkalizersDe-Alkalizers• Reverse OsmosisReverse Osmosis
CLARIFICATION / SEDIMENTATIONCLARIFICATION / SEDIMENTATION
For the removal high suspended solids, For the removal high suspended solids, above 50 mg/l. Specially suitable for canal above 50 mg/l. Specially suitable for canal / river (surface water treatment)./ river (surface water treatment).
FILTERATIONFILTERATION
For the removal of suspended solids (TDS For the removal of suspended solids (TDS <50 ppm)<50 ppm)
Different Types of filling media are used,Different Types of filling media are used,
based on particular application.based on particular application.
FILTERATION SPECTRUMFILTERATION SPECTRUM
LIME SODA SOFTENINGLIME SODA SOFTENING
Removes hardness associated with Removes hardness associated with alkalinityalkalinity
Precipitation of calcium and Precipitation of calcium and magnesium carbonate produces huge magnesium carbonate produces huge volume of sludgevolume of sludge
Sludge disposal causes problemSludge disposal causes problem
Decreases the total dissolved solidsDecreases the total dissolved solids
Blow down rate decreasesBlow down rate decreases
ACIDIFICATIONACIDIFICATION
Lowers p H Lowers p H
Decreases Scaling IndicesDecreases Scaling Indices
Increases calcium sulphate scalingIncreases calcium sulphate scaling
No impact on TDS of feed waterNo impact on TDS of feed water
Increases blowdown rateIncreases blowdown rate
WATER FOR COOLING TOWERS WATER FOR COOLING TOWERS & HEAT EXCHANGERS& HEAT EXCHANGERS
Fundamentals:Fundamentals:1.1. Air Quality affects Water QualityAir Quality affects Water Quality2.2. FilterationFilteration3.3. Contamination & TurbidityContamination & Turbidity4.4. Blow DownBlow Down5.5. Chemical TreatmentChemical Treatment (Scale Preventation, Corrosion Control, Control of (Scale Preventation, Corrosion Control, Control of
Biological Growth, Foaming, Control of Suspended Biological Growth, Foaming, Control of Suspended Impurities)Impurities)
WATER QAUALITY AT DIFFERENT LOCATIONWATER QAUALITY AT DIFFERENT LOCATION
LocationsLocations
11 Shahkot Khurianwala AreaShahkot Khurianwala Area 4. Mirpur Mathelo4. Mirpur Mathelo
22 Raiwind Manga Mandi AreaRaiwind Manga Mandi Area 5. Rawalpindi Area5. Rawalpindi Area
33 Nishatabad Area FaisalabadNishatabad Area Faisalabad
ElementsElements UnitsUnits 11 22 33 44 55
CalciumCalcium Ca++Ca++ CaCO3CaCO3 190190 4545 138138 210210 150150
MagnesiumMagnesium Mg++Mg++ CaCO3CaCO3 279279 1313 346346 180180 150150
SodiumSodium Na+Na+ CaCO3CaCO3 10851085 706706 31993199 859859 370370
Total CationTotal Cation CaCO3CaCO3 15541554 764764 36833683 12491249 670670
BicarbonatesBicarbonates HCO3-HCO3- CaCO3CaCO3 711711 250250 775775 400400 196196
ChlorideChloride Cl-Cl- CaCO3CaCO3 421421 493493 17541754 465465 282282
SulfateSulfate SO4--SO4-- CaCO3CaCO3 422422 2121 11541154 384384 192192
Total AnionTotal Anion CaCO3CaCO3 15541554 764764 36833683 12491249 670670
Total HardnessTotal Hardness CaCO3CaCO3 469469 5858 482482 390390 300300
Carbonate HardnessCarbonate Hardness CaCO3CaCO3 469469 5858 482482 390390 104104
Non Carbonate HardnessNon Carbonate Hardness CaCO3CaCO3 00 00 00 1010 196196
m Alkalinitym Alkalinity CaCO3CaCO3 711711 250250 775775 400400 196196
Sodium AlkalinitySodium Alkalinity CaCO3CaCO3 242242 192192 293293 1010 00
pHpH pH scalepH scale 7.87.8 7.857.85 7.97.9 7.57.5 7.97.9
Total Dissolved SolidsTotal Dissolved Solids mg/lit.mg/lit. 22352235 10161016 50005000 18201820 872872
Scale is a very common problem encountered in
cooling water systems. Scale retards heat exchange,
accelerates fouling, promotes certain types of corrosion and
microbial growth and increases pumping back
pressure.
These all can translate to unscheduled delays, decreased plant efficiency, reduced productivity and reduced
profitability.
ScaleScale
Boiler Inspector Only Checks For Boiler Inspector Only Checks For Safety, NOT EFFICIENCYSafety, NOT EFFICIENCY
Carbonic Acid Corrosion on Mild SteelCarbonic Acid Corrosion on Mild Steel
Results in a thinning and grooving of the metal surface
SOFTENING THROUGH ION SOFTENING THROUGH ION EXCHANGEEXCHANGE
• Removal of Calcium & Magnesium by Removal of Calcium & Magnesium by Sodium ionsSodium ions • Soft Water does not reduce total Soft Water does not reduce total dissolved Solids.dissolved Solids.
• To some extent Iron removalTo some extent Iron removal
SOFTENING THROUGH ION SOFTENING THROUGH ION EXCHANGEEXCHANGE
• Removal of Calcium & Magnesium by Removal of Calcium & Magnesium by Sodium ionsSodium ions • Soft Water does not reduce total Soft Water does not reduce total dissolved Solids.dissolved Solids.
• To some extent Iron removalTo some extent Iron removal
SOFTENING THROUGH ION SOFTENING THROUGH ION EXCHANGEEXCHANGE
The softening of water by ion exchange The softening of water by ion exchange involves the replacement of calcium and involves the replacement of calcium and magnesium ions in water by an equivalent magnesium ions in water by an equivalent number of sodium ions. This eliminates the number of sodium ions. This eliminates the undesirable characteristics of hardness in undesirable characteristics of hardness in water, as sodium salts do not form scale. The water, as sodium salts do not form scale. The chemical reaction is as under:chemical reaction is as under:
SOFTENING THROUGH ION SOFTENING THROUGH ION EXCHANGEEXCHANGEBasic Ion Exchange Mechanism is as follows:Basic Ion Exchange Mechanism is as follows:
2RcSO3Na + Ca(HCO3)2 = (RcSO3)2Ca + 2RcSO3Na + Ca(HCO3)2 = (RcSO3)2Ca + 2NaHCO32NaHCO3
(Sodium (Calcium (Calcium (Sodium (Calcium (Calcium (Sodium(Sodium
Exchange Bicarbonate Exchange Exchange Bicarbonate Exchange BicarbonateBicarbonate
Regenerated in Raw Water) Exhausted In SoftRegenerated in Raw Water) Exhausted In Soft Resin) Resin) Water)Resin) Resin) Water)
SOFTENING THROUGH ION SOFTENING THROUGH ION EXCHANGEEXCHANGE
The sodium ion exchanger contains only a finite The sodium ion exchanger contains only a finite number of exchangeable sodium ions. This number number of exchangeable sodium ions. This number is known as the capacity of the resin. When this is known as the capacity of the resin. When this capacity has been exhausted, i.e., sodium ions have capacity has been exhausted, i.e., sodium ions have been replaced by calcium or magnesium, been replaced by calcium or magnesium, regeneration of the resin back to sodium form regeneration of the resin back to sodium form becomes necessary. Resin bed is regenerated with a becomes necessary. Resin bed is regenerated with a downward flow of brine. Later, resin bed is rinsed downward flow of brine. Later, resin bed is rinsed free off brine. The chemical reaction is as under:free off brine. The chemical reaction is as under:
SOFTENING THROUGH ION SOFTENING THROUGH ION EXCHANGEEXCHANGE
Regeneration of Resin through brine solution is as follows:Regeneration of Resin through brine solution is as follows:
(RcSO3)2Mg,Ca + 2NaCl = 2RcSo3Na + MgCl2 , CaCl2(RcSO3)2Mg,Ca + 2NaCl = 2RcSo3Na + MgCl2 , CaCl2
(Exhausted (Brine) (Regenerated (Effluent)(Exhausted (Brine) (Regenerated (Effluent) Resin) Resin)Resin) Resin)
DE-ALKALIZERSDE-ALKALIZERS
Removes cations associated withRemoves cations associated with alkalinity from the water.alkalinity from the water.
De gasifier is used for removal of De gasifier is used for removal of bicarbonate alkalinitybicarbonate alkalinity
Effective for high alkalinity watersEffective for high alkalinity waters
TDS reduces equivalent to alkalinity.TDS reduces equivalent to alkalinity.
DE-ALKALIZERDE-ALKALIZER
Basic Ion Exchange Mechanism is as Basic Ion Exchange Mechanism is as follows:follows:
2RcSO3H + Ca(HCO3)2 = (RcSO3)2Ca + 2H2CO3, HCl, H2SO42RcSO3H + Ca(HCO3)2 = (RcSO3)2Ca + 2H2CO3, HCl, H2SO4 (Sodium (Ca, Mg, Na (Ca, Mg, Na (Acid) (Sodium (Ca, Mg, Na (Ca, Mg, Na (Acid)
Exchange Bicarbonates, Exchange Exchange Bicarbonates, Exchange Regenerated Chlorides & Exhausted Regenerated Chlorides & Exhausted Resin) Sulphates) Resin) Resin) Sulphates) Resin)
REVERSE OSMOSISREVERSE OSMOSIS
REVERSE OSMOSISREVERSE OSMOSIS
FeedFeedSolution which enters the system and is Solution which enters the system and is pressurized.pressurized.
PermeatePermeateSolution which passes through the membrane Solution which passes through the membrane and is collected for use.and is collected for use.
RejectRejectThe percentage of dissolved material that The percentage of dissolved material that does not pass through membrane.does not pass through membrane.
REVERSE OSMOSISREVERSE OSMOSIS
PassagePassageThe percentage of dissolved material that does The percentage of dissolved material that does pass through the membranepass through the membrane
RecoveryRecoveryThe ratio of permeate rate to feed rateThe ratio of permeate rate to feed rate
Permeate RatePermeate RateRecovery (%)Recovery (%) = ------------------- = ------------------- × 100× 100
Feed RateFeed Rate
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