Industrial Systems Design & Integration 2

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Cont..Cont..

Distribution of Earths water


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W hat is DesalinationW hat is Desalination

Desalination is the process of removingDesalination is the process of removing

dissolved solidsdissolved solids primarily saltsprimarily salts fromfromwater.water.


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O bjectivesO bjectives

Making use of nonMaking use of non- -conventional water conventional water resources.resources.

Supply fresh water to wide areas in Gaza.Supply fresh water to wide areas in Gaza.

Taking into account technical, economical,Taking into account technical, economical,

environmental,environmental, legal and social aspects.legal and social aspects.


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H indrance in GazaH indrance in Gaza

W astewater is flow to the sea.W astewater is flow to the sea.This need water recycling system.This need water recycling system.

Electricity.Electricity.Chemicals.Chemicals.


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Issues in water DesalinationIssues in water DesalinationEnergy consumptionEnergy consumption

--Minimisation strategiesMinimisation strategies

--Use of solar, PV, wind, hybrid systems for small plantsUse of solar, PV, wind, hybrid systems for small plants

CostCost

Environmental ImpactEnvironmental Impact--No guidelines for discharge, other than mixing zoneNo guidelines for discharge, other than mixing zone--Saline concentrate dispersion into receiving streamSaline concentrate dispersion into receiving stream--Nutrient and solids load minimisationNutrient and solids load minimisation

Intake facility designIntake facility design--minimisation of aquatic life entrainmentminimisation of aquatic life entrainment

Desalinated water qualityDesalinated water quality-- H ealth aspectsH ealth aspects--Corrosion aspects (alkalinity, chloride)Corrosion aspects (alkalinity, chloride)--Aesthetics (effects of blending with existing supplies) Aesthetics (effects of blending with existing supplies)


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Desalination TechnologiesDesalination Technologies

There are various methods to separate theThere are various methods to separate thesalts from the water to render it useful for salts from the water to render it useful for

drinking purposes.drinking purposes.The two most common and generallyThe two most common and generallyproven largeproven large- -scale methods are:scale methods are:

11) distillation processes and,) distillation processes and,22) membrane) membrane- -based processes.based processes.


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Cont..Cont.. Also, it is more economically attractive if operating in Also, it is more economically attractive if operating inconjunction with steam power generation because theconjunction with steam power generation because thesteam released from the power generation plant can besteam released from the power generation plant can beadvantageously used as input into the desalinationadvantageously used as input into the desalinationplant.plant.

In modern systems the H eat source may be one of In modern systems the H eat source may be one of Renewable Energy sources such as solar Energy andRenewable Energy sources such as solar Energy andW indmills .W indmills .

Distillation technologies account for approximatelyDistillation technologies account for approximatelyoneone--half of the world s installed desalination capacityhalf of the world s installed desalination capacity


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Solar Powered DesalinationSolar Powered DesalinationExampleExample 1 1

In the late eighteen hundreds in Chile, this system isIn the late eighteen hundreds in Chile, this system issaid to have producedsaid to have produced 55 ,,000000 Gallons per day inGallons per day in 5 05 0,,000000Square Feet.Square Feet.

The counter-current gradient exposure to the condensation surfaceassures significantly higher energy capture and water production


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Laminar Solar DesalinationLaminar Solar Desalination

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Cellular Element


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Solar Powered DesalinationSolar Powered Desalination

ExampleExample 2 2D esalination powered by renewable energyD esalination powered by renewable energyusing photovoltaic cells, possibly inusing photovoltaic cells, possibly inconjunction with a fuel cell.conjunction with a fuel cell.


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MembraneMembrane- -based technologiesbased technologies

MembraneMembrane- -based technologies utilize semibased technologies utilize semi- -permeable membranes to separate the saltspermeable membranes to separate the salts

from the water. There are two types of from the water. There are two types of membrane processes:membrane processes:

1)1) ElectroElectro--dialysis reversal (EDR) process anddialysis reversal (EDR) process and2)2) reverse osmosis (R O ) process.reverse osmosis (R O ) process.


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ElectroElectro--dialysis Reversal (EDR) processdialysis Reversal (EDR) process

The EDR process utilizes electricity toThe EDR process utilizes electricity toenergize opposing electrodes to attractenergize opposing electrodes to attractand separate out positive and negativeand separate out positive and negativeions of the dissolved salts from a salineions of the dissolved salts from a salinewater supply.water supply.

EDR systems may be used with water EDR systems may be used with water containing low amounts of TDS. H owever,containing low amounts of TDS. H owever,when TDS levels exceedwhen TDS levels exceed 3 3,,000000 mg/l, R O mg/l, R O systems are typically the preferred choicesystems are typically the preferred choice

for desalinationfor desalination


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Reverse osmosis (R O ) processReverse osmosis (R O ) process

O smosis refers to the natural tendency of water to flowO smosis refers to the natural tendency of water to flowthrough a semithrough a semi- -permeable membrane and dilutepermeable membrane and diluteliquids with higher salinityliquids with higher salinity

This tendency is measured in terms of the osmoticThis tendency is measured in terms of the osmoticpressure. In a water desalination operation, the R O pressure. In a water desalination operation, the R O process utilizesprocess utilizes H igh PressureH igh Pressure as the driving force toas the driving force toovercome the osmotic pressure and to reverse theovercome the osmotic pressure and to reverse the

flow through the membrane; the membrane preventsflow through the membrane; the membrane preventsthe flow of the dissolved solids while allowing the flowthe flow of the dissolved solids while allowing the flowof water. Typical R O operating pressures range fromof water. Typical R O operating pressures range from200200 toto 45 045 0 psi for brackish groundwater plants andpsi for brackish groundwater plants and8 008 00 toto 11,,200200 psi for seawater plantspsi for seawater plants


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ExampleExample


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Cont..Cont..


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Advantages of water Desalination Advantages of water Desalination

provide a superior quality product regardlessprovide a superior quality product regardlessof the source water qualityof the source water quality

water desalination has over more conventionalwater desalination has over more conventionalwater supply sourceswater supply sources


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Disadvantages of water DesalinationDisadvantages of water Desalination

water desalination is its high use of water desalination is its high use of energy.energy.

Approximately one third of the operational Approximately one third of the operationalcosts of a water desalination facility is thecosts of a water desalination facility is thepower consumptionpower consumption

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Industrial Systems Design & Integration 2