WATER CHEMISTRY & APPLICATIONS IN WATER TREATMENT WATER SOURCES

WATER TREATMENT PROCESSES

WATER QUALITY REQUIREMENTS FOR PROCESS INDUSTRIES

WATER SOURCES1.WELL WATER a. SHALLOW WELLS b. DEEP WELLS

2.SURFACE WATER a. RIVER b. LAKE

3.SEA WATER a. OPEN SEA INTAKE b. BEACH WELLS

WATER CHEMISTRYWater Composition Suspended Impurities Suspended Solids

- Organics Compounds - Iron- Silt- Bacteria

WATER CHEMISTRY Water Composition Dissolved Impurities Cations- Calcium (Ca) - Magnesium (Mg) - Sodium (Na) - Potassium (K)- Barium (Ba)- Strontium (Sr)

WATER CHEMISTRYAnions - Carbonate (CO3)- Bicarbonate (HCO3)- Sulphate (SO4)- Nitrate (NO3)- Nitrite (NO2)- Chloride (Cl)- Floride (F)- Silica (Si)

WATER CLASSIFICATIONS BASED ON TOTAL DISSOLVED SOLIDS (TDS)Tap Water < 1000 ppm BRACKISH 1000-5000 ppmHIGLLY BRACKISH 5000-15000 ppmSALINE 15000-30000 ppmSEA WATER 30000-40000 ppmBRINE 40000-300000 ppm

WATER TREATMENT PROCESSESClarification / Sedimentation Filteration Lime Soda Softening Softening Through Ion Exchange Demineralization De-Alkalizers Reverse Osmosis

CLARIFICATION / SEDIMENTATION

For the removal high suspended solids, above 50 mg/l. Specially suitable for canal / river (surface water treatment).

FILTERATION

For the removal of suspended solids (TDS

FILTERATION SPECTRUM

LIME SODA SOFTENING Removes hardness associated with alkalinity

Precipitation of calcium and magnesium carbonate produces huge volume of sludge

Sludge disposal causes problem

Decreases the total dissolved solids

Blow down rate decreases

ACIDIFICATIONLowers p H

Decreases Scaling Indices

Increases calcium sulphate scaling

No impact on TDS of feed water

Increases blowdown rate

WATER FOR COOLING TOWERS & HEAT EXCHANGERSFundamentals:Air Quality affects Water QualityFilterationContamination & TurbidityBlow DownChemical Treatment (Scale Preventation, Corrosion Control, Control of Biological Growth, Foaming, Control of Suspended Impurities)

ScaleScale 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.

Boiler Inspector Only Checks For Safety, NOT EFFICIENCY

Carbonic Acid Corrosion on Mild SteelResults in a thinning and grooving of the metal surface

SOFTENING THROUGH ION EXCHANGE Removal of Calcium & Magnesium by Sodium ions Soft Water does not reduce total dissolved Solids.

To some extent Iron removal

SOFTENING THROUGH ION EXCHANGE Removal of Calcium & Magnesium by Sodium ions Soft Water does not reduce total dissolved Solids.

To some extent Iron removal

SOFTENING THROUGH ION EXCHANGE The softening of water by ion exchange involves the replacement of calcium and magnesium ions in water by an equivalent number of sodium ions. This eliminates the undesirable characteristics of hardness in water, as sodium salts do not form scale. The chemical reaction is as under:

SOFTENING THROUGH ION EXCHANGEBasic Ion Exchange Mechanism is as follows:

2RcSO3Na + Ca(HCO3)2 = (RcSO3)2Ca + 2NaHCO3 (Sodium (Calcium (Calcium (Sodium Exchange Bicarbonate Exchange Bicarbonate Regenerated in Raw Water) Exhausted In Soft Resin) Resin) Water)

SOFTENING THROUGH ION EXCHANGE The sodium ion exchanger contains only a finite number of exchangeable sodium ions. This number is known as the capacity of the resin. When this capacity has been exhausted, i.e., sodium ions have been replaced by calcium or magnesium, regeneration of the resin back to sodium form becomes necessary. Resin bed is regenerated with a downward flow of brine. Later, resin bed is rinsed free off brine. The chemical reaction is as under:

SOFTENING THROUGH ION EXCHANGE

Regeneration of Resin through brine solution is as follows:

(RcSO3)2Mg,Ca + 2NaCl = 2RcSo3Na + MgCl2 , CaCl2

(Exhausted (Brine) (Regenerated (Effluent) Resin) Resin)

DE-ALKALIZERS

Removes cations associated with alkalinity from the water.

De gasifier is used for removal of bicarbonate alkalinity

Effective for high alkalinity waters

TDS reduces equivalent to alkalinity.

DE-ALKALIZERBasic Ion Exchange Mechanism is as follows:

2RcSO3H + Ca(HCO3)2 = (RcSO3)2Ca + 2H2CO3, HCl, H2SO4 (Sodium (Ca, Mg, Na (Ca, Mg, Na (Acid) Exchange Bicarbonates, Exchange Regenerated Chlorides & Exhausted Resin) Sulphates) Resin)

REVERSE OSMOSIS

REVERSE OSMOSISFeedSolution which enters the system and is pressurized.

PermeateSolution which passes through the membrane and is collected for use.

RejectThe percentage of dissolved material that does not pass through membrane.

REVERSE OSMOSISPassageThe percentage of dissolved material that does pass through the membrane

RecoveryThe ratio of permeate rate to feed rate Permeate RateRecovery (%)= ------------------- 100 Feed Rate

Design DataRaw Water AnalysisTotal Dissolved Solids(ppm):1820Total Suspended Solids (ppm):10Calcium ppm as CaCO3:210Magnesium ppm as CaCo3:180Total Alkalinity (ppm):420Total Hardness ppm as Caco3:390PH Valve:7.5Conductivity (Us/cm):2600

Operating DataQuantity:04 Nos.Capacity/Softener:90m3/hrService time/ Softener:8hrRegeneration time/Softener :02 hrs. (approximately)Output/Regeneration/Softener:720 m3Resin make:Rohm & HaasResin type:Amerlite lR-120Resin volume/softener:5250 litersRegeneration mode:Counter Current flowRegenerant:NaClRegenerant concentration:10% W/W NaclRegeneration Level:133 g Salt / Liter ResinNacl Consumption per regn:700kg (100 % W/W)Softener Vessel Data

Regeneration DataRegeneration Data

DescriptionTime (min)Flow Rate(Liters/Hr)Backwashing1040000-75000Settling05-Brine injection (23% W/V NaCl)305200Dilution water(30)7884Brine injection (10% W/V NaCl)(30)13085Slow rinse307884Fast rinse (purge)1590000Total90

Regeneration MethodBack WashFor 10 MinutesFor removal of suspends, fromTop of resin bedSettingFor 05 minutesFor settle down the resinBrine InjectionFor 30 MinutesSlow RinseFor 30 MinutesFor brine washingFast RinseFor 15 MinutesNormal Operation

Sodium Chloride NaCl Common salt

DescriptionRecommendationPurity97%Water content-Insoluble matter0.1%Sulfate1%Ca+2 & Mg +20.5Soluble ironNot detectableSand or clayNilSoluble alkalinity as CaCO3-

Permeate Flow:88.0gpm System Flux : 17.6gfdSystem Recovery:70.0% Acid Dosage, H2SO4 98%:0.0ppmFeedwater Temp:28.0C Feed CO2: 25.0ppmElement Age:0.0years Flux Decline Coef.: -0.025%Raw Water pH:7.53-yr S.P.I.F: 1.3Feed Pressure:191.4psi Concentrate Pressure: 159.2psiRecirc. Flow:0.0gpm Blend Flow: 0.0gpm Permeate Flow:88.0gpmSystem Flux :17.6gfdSystem Recovery:70.0%Acid Dosage, H2SO4 98%:0.0ppmFeedwater Temp:28.0CFeed CO2:25.0ppmElement Age:0.0yearsFlux Decline Coef.:-0.025%Raw Water pH:7.53-yr S.P.I.F:1.3Feed Pressure:191.4psiConcentrate Pressure:159.2psiRecirc. Flow:0.0gpmBlend Flow:0.0gpm

To determine Carbon dioxide content from given water analysis reportTo determine LSI from water analysis ReportTo calculate p Ca and P alkalinity from water analysis reportHeres a classic picture showing the wastage caused by CO2 in the condensate. The corrosive effect of carbon dioxide dissolved in condensate is a general overall loss of metal below the surface of the liquid. The carbonic acid basically dissolves away the pipe. These problems may be found throughout the system or in isolated locations. Because the metal is thinnest in threaded areas, they are the most susceptible to carbonic acid attack. Bottom grooving of horizontal pipe (as shown above) is also a frequent problem; but because of the thicker tube wall, it takes longer to fail.