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  • Department of Bioresource Engineering

    DesignProposalforaRenewableEnergyPoweredDesalinationSystem

    Presentedby

    MehdielmasriId:260188119

    GlebTchetkovId:260173901

    To

    Dr.RaghavanDesign2:BREE490

    MacdonaldCampus

    McGillUniversity3/12/2009

    BIORESOURCEENGINEERING,2111 AD,

    STEANNEDEBELLEVUE,H9X3V9,1LAKESHORERO

    QUEBEC,CANADA

    1

  • EXECU IVESUMMARYT

    TheKingdomofJordanisthe10thwaterpoorestcountryintheworldandthe4thwaterpoorest

    countryintheMiddleEast.Thenaturalwaterresourcesofthecountryarenotsufficienttomeet

    thedemandsofthepopulationandbecauseofthiswaterrationinghasbeeninplacesincethe

    1980s.Currently,theeconomicallyviableharnessingofsurfacewaterhasbeenmaximized,

    groundwaterisbeingpumpedat160%ofthesustainableyield,andnonrenewablefossilwateris

    alsobeingutilized.Arapidlygrowingpopulationandindustrialsectorthreatentoexacerbatethe

    watershortageintheverynearfuture.Jordanianscientistsinpartnershipwithinternational

    organizationshavedeterminedthatdesalinationofsalinewaterwillplaythemostimportantrole

    inalleviatingthecountryswaterscarcityproblems.Thisdocumentwilloutlineadesignproposal

    foradesalinationunittobepoweredbyarenewableenergysourcethatwillprovidesufficient

    reshwaterfortheneedsofasmallruralcommunityinJordan.f

    2

  • TableofContents

    ExecutiveSummary........................................................................................................................................2

    ListofFiguresandTables.............................................................................................................................4

    IntroductionGlobalWaterIssues...................................................................5

    1.ProblemIdentificationJordansWaterShortage.........................................................................7

    2.ObjectiveandScope..................................................................................................................................10

    3.LiteratureReview......................................................................................................................................11

    3.1DesalinationTechnologies......................................................................................................11

    3.2RenewableEnergyTechnologies..........................................................................................15

    3.3PreandPostTreatmentTechnologies...19

    3.4BrineDisposalMethods...........................................................................................................22

    4.DesignMethodology.................................................................................................................................26

    4.1DescriptionofSiteandContext.............................................................................................26

    4.2SelectionofTechnologies........................................................................................................28

    4.2.1RenewableEnergySystem......................................................................................28

    4.2.2DesalinationUnit.......................................................................................................28

    4.2.3Pre/PostTreatmentUnit........................................................................................31

    4.2.4BrineDisposalMethod.............................................................................................31

    4.3DesignApproach.........................................................................................................................32

    5.ExpectedResults.........................................................................................................................................38

    6.TimeFrame...................................................................................................................................................39

    7.CostEvaluation...........................................................................................................................................39

    8.Conclusion.....................................................................................................................................................40

    Acknowledgements.........................................................................................................................................41

    References.........................................................................................................................................................42

    3

  • ListofFigures

    Figure1:Solarstillschematic.........................................................................................................................................12

    Figure2:Potentialdesalinationtechnologycombinationsforgeothermalenergy................................16

    Figure3:Potentialdesalinationtechnologycombinationsforsolarenergy..............................................17

    Figure4:Potentialdesalinationtechnologycombinationsforwindenergy..............................................18

    Figure5:Saltgradientnonconvectivesolarpondschematic24

    Figure6:MeanmonthlyvariationoftherecordedglobalsolarradiationforJordan.27

    Figure7:MeanmonthlyvariationoftherecordedsunshinedurationforJordan...................................27

    Figure8:Renewableenergydesalinationcombinationsworldwide.........................................................29

    Figure9:RESdesalinationdesignalgorithm34

    igure10:BlockdiagramoftheproposedPVpoweredBWROdesalinationplant................................35F

    ListofTables

    Table1:Comparisonofenergycostsfromvarioussources...............................................................................18

    Table2:DesalinationTechnologiesOverview..29

    4

  • INTRODUCTION

    Therearemanyissuesrelatedtowaterthatnationsarestrugglingwithinthe21stcentury.

    Currently,aboutonequarteroftheworldspopulation,orabout1.2billionpeople,lacksaccessto

    sufficientwaterofgoodquality(Rijsberman,2005).Thisproblemisonlyexacerbatedastheworld

    populationcontinuestoclimb,asithasbeenshownthatwaterusageincreasesattwicetherateof

    opulationincrease(Eltawiletal.,2009).p

    Since1950,globalwaterusehastripledandinthenexttwentyyears,itisestimatedthathumans

    willrequire40%morewaterthanwecurrentlyuse[in2000](Eltawiletal.,2009).Consequently,

    waterscarcity,lackofaccessibility,waterqualitydeterioration,andinsufficientrechargeof

    groundwaterandoverextractionoffreshwaterareallincreasinginseverityaseconomicgrowth

    leadstopopulationgrowthandwhichrequireseverexpandingirrigationforhighlyproductive

    agriculturalsystems.Thisshortageofwaterisaseriousthreattoworldpeaceandsecurityinthe

    earfuture(Eltawiletal.,2009).n

    Actionstakentoalleviatewaterscarcitycanbegroupedintothreecategories:preservationofthe

    qualityofcurrentsupplies,increasingefficiencyofcurrentwaterusage,andincreasingtheoverall

    quantityofavailablefreshwater(Eltawiletal.,2009).Methodsundertakentoaccomplishthese

    goalsincludedesalinationofsalinewater,rainwaterharvesting,wastewaterreuse,andwater

    mportation(Jaberetal.,2001).i

    WaterissuesareespeciallysevereintheMediterraneanbasin,southernEurope,theMiddleEast,

    AsiaandAfricawherethereisaconditionofphysicalscarcityofwater.Verylargeportionsofthe

    peoplestrickenbywatershortagesarethosewholiveinremoteruralareas,wherethesocio

    economicconditionspreventtherapidimplementationofwatertreatmenttechnology

    (Rijsberman,2005).Undevelopedruralregionswithoutaccesstotheelectricalgridtypicallydo

    nothaveaccesstotheinfrastructurerequiredforlargescaledesalinationplantsnortheneedfor

    suchfacilities.Consequently,thereisanapparentneedtodevelopdesalinationtechnologywhich

    illfunctionoffthegridandonasmaller,villagescale.

    5

    w

  • Fortunately,islandnationssufferingfromsaltwaterintrusiontypicallyhavehighwindresources.

    Thearidandsemiaridregionsoftheworldarealsosomeofmostsolarresourcerichareas,which

    makesense,becausethedriestareastendtohaveincreasedinsolarirradiationbecauseoftheir

    proximitytotheequator.Undertheseconditions,thecouplingofarenewableenergysystem

    (windpower,solarthermal,geothermal)tothedesalinationprocessmakeswatertreatment

    easibleinremoteareas.(Eltawiletal.,2009).f

    6

  • 1. PROBLEMIDENTIFICATION

    Incountrieswithahighpopulationgrowthrateandfastsocioeconomicdevelopment,water

    demandandwastewaterproductionissteeplyincreasingandthegapbetweenwatersupplyand

    demandisgettingwider.Fortunately,efficienttechnologieshavebeendevelopedtotreat

    wastewaterandbrackishwaterdesalinationforcommunitieswherefreshwaterisscarce.A

    numberofsuchcommunitiesinaridregionshaveturnedtodesalinationtechnologiesbecauseofit

    eingarelativelyfeasiblealternativeforfreshwaterproduction.b

    Jordanspopulationreached5.3millionin2002andcontinuestogrowatanannualrateof3.6%.

    ThisisaveryhighrateofgrowthwhencomparedtoCanadas1.1%populationgrowthrate

    (StatisticsCanada).Annualrainfallrangesfrom600mminthehighlandsofNorthwesternJordan

    to130mmorlessinthedesertsintheEastandSouth,whichmakeup91%ofthesurfaceareaof

    thecountry.ThisisaverysmallamountofprecipitationwhencomparedtoCanadasrangeof250

    mminthefarNorthtoover900mmintheAtlanticProvinces.Duetoveryhighevaporationrates

    intheJordan,85%oftherainfallislosttotheatmosphere.Oftheremaining15%,4%goes

    towardstherechargeofgroundwaterandtheother11%isequaltoavailablesurfacewater

    Mohsen,2007).(

    Jordanhasthreemainsourcesofsurfacewater,theZarqa(Jakkob)andYarmoukRivers,which

    bothdrainwestwardtotheJordanRiverandeventuallytotheDeadSea.TheJordanRiverforms

    theborderbetweenPalestineandJordanwhiletheYarmoukRiverformstheborderwithIsraelin

    theNorthwest,totheSouthoftheSeaofGalilee(LakeTiberias).Fartherupstreamandtothe

    ortheast,theYarmoukalsoservesastheborderbetweenJordanandSyria.N

    7

    TheZarqaRiverwatersystemisbecomingincreasinglypollutedfromtheindustrialareaaround

    theZarqaAmmanregion,where70%ofJordansindustryislocated,anditsabilitytoprovide

    cleanwaterhasbeengreatlydiminished.SyriahasbuiltanumberofdamsontheYarmoukin

    ordertodivertwaterforitsownpurposes.Perhapsanevengreaterstrainonthesurfacewater

    resourcesforJordanhasbeentheconstructionoftheNationalWaterCarrierbyIsraelin1967,

    whichtakeswaterfromupperJordanRiveratLakeTiberias.Theconstructionofthisprojecthas

  • significantlyreducedtheflowofthelowerJordanRiver(MarkZeitoun).Unfortunately,Syriaand

    IsraelhavetakenadvantageoftheirupstreamriparianpositionwithoutregardforJordansfair

    hareofthewateravailablefromsourcessharedbyallthreecountries(Mohsen,2007).s

    JordansconflictwithIsraelwasinpartduetotheissueofunfairwatersharingpractices.In1994,

    JordanandIsraelsignedapeacetreatywhichguaranteedanadditional215millioncubicmeters

    (MCM)ofwaterforJordanthroughnewdams,diversions,pipelines,anddesalinationplants.Even

    iththisimprovement,Jordanisstillaverywaterpoornation.w

    Jordanhasoneoftheworldslowestpercapitawaterresources.Waterscarcecountriesare

    definedashavingaccesstolessthan1000m3/yearpercapita.In1996,Jordaniansconsumedan

    averageoflessthan175m3/yearpercapita.In1997,atotalof882millioncubicmeters(MCM)of

    waterwasusedinJordan.Ofthistotal,225MCMexceededthesustainablegroundwateryieldand

    anadditional70MCMwassourcedfromnonrenewablefossilwater.Fossilwaterisgroundwater

    thatwasaccumulatedduringatimeofadramaticallydifferentclimateintheregionandthathas

    beensealedbygeologicalprocessesforthousandsofyears.Withoutanincreaseinoverall

    availabilityofwaterandaconstantpopulationgrowthrate,thepercapitaconsumptionofwater

    coulddropdownto91m3/yearbytheyear2025(Mohsen,2007).ThiswouldrelegateJordanto

    absolutewaterscarcitystatus,themostseverelevelofwaterscarcity,recognizedbytheUNtobe

    essthan100m3/yearpercapita(Rijsberman,2005).l

    Itisalsoimportanttonotethatcontinualoverextractionofgroundwaterunderminesthe

    sustainabilityofthesealreadylimitedwaterresourcestoprovidefreshwaterintothefuture.

    Groundwaterresourcesarebeingexploitedfor160%oftheirsustainableyield.Insomeregions,

    overextractionhasleadtoa5meterdropinwaterlevelsandatripledsalinity.Ifcurrenttrends

    continue,someoftheseoverexploitedbasinswillrundrywithinthenextfewyears.Dropping

    watertablelevelsaswellastheincreasingsalinityofgroundwaterarethedirectresultofover

    extractionandimplyincreasingscarcityandahighercostoffreshwaterinthefuture(Mohsen,

    007).2

    8

  • ThereareanumberoffactorswhichexacerbatetheissueofwatershortageinJordan.Thelow

    availabilityoffreshwaterthatcanbepumpedeconomically,incombinationwithlargeinfluxesof

    refugeesandarapidlygrowingpopulation,improvingstandardsofliving,aswellasthegeo

    politicalsituationintheregionaresomeofthefactorsthathavecausedthecurrentconditionof

    waterscarcityintheregion.Wastewatertreatmentplantsoperatingbeyonddesigncapacityare

    becomingasignificantsourceofpollutionforgroundwateraswell.InefficienciesinJordans

    irrigatedagriculturesystemshavecaused70%ofavailablewatertobeallocatedtothe

    agriculturalsector.Increasedeffectivenessinirrigationwillplayanimportantpartinfreeingup

    morewaterforthegrowingdomesticandindustrialneedsofthecountry.Inaddition,becausethe

    KingdomofJordanspriorityistoprovidepotablewaterfordomesticuse,waterresourceswillbe

    allocatedawayfromagricultureandtowardsthedomesticandindustrialsectors.Thismakes

    senseeconomicallysincetheproductvalueof1m3ofwaterconsumedinindustrialproductionis

    verymuchhigherthanforthesameamountconsumedforirrigatingwheatfieldsororchards.In

    Jordan,forexample,productivityperunitofconsumedwateris40timeshigherinindustrythan

    inagriculture,andemploymenteffectis13timeshigher(Mohsen,2007).Foraridcountries,the

    optimizationofwaterusemayimplythatincreasedimportationoffoodfromnearbyregionsis

    ecessary.n

    ThoughJordanianscurrentlyconsumeabout175m3/yearpercapita,domesticusageofwater

    accountsforonly20%ofthetotalandroughlyamountsto96L/daypercapita.Accordingtothe

    UN,100L/daypercapitaistheminimumrequirementforasettledpopulationtohaveproper

    sanitationandareasonablestandardoflife.Thesefiguresshedlightontheseverityofthewater

    crisisinJordan,asunsustainablepumpingofwaterresourcesisalreadyoccurringinordertokeep

    qualityoflifeatanadequatelevel.Accesstowaterishighlylimitedtoallsectorsofthecountry

    andespeciallysoduringthesummermonthsofMaySeptember,duringwhichabsolutelynorain

    falls.Duringthistime,thecapitalcityofAmmanhaswateraccessforafewhoursonceeveryseven

    aysandruralareasreceiveadeliveryofwateronceeverytwelvedays(Dennyet.al,2008)d

    9

  • . OBJECTIVESANDSCOPE2

    Jordanswatershortageneedstobeaddressedquicklybeforeveryseriousenvironmentaland

    socialproblemsarise.Becauseoftheunreliabilityandinefficienciesincurredinthetransportof

    treatedwateroverlongdistancestoremotecommunitiesinJordan,weproposetocompletea

    systemdesignforasmallscaledesalinationunitpoweredbyalocallyabundantsourceof

    renewableenergywhichcaneconomicallybringwaterautonomytoanotherwisedisenfranchised

    roupofpeople.g

    ithinthescopeofthisprojectwillbetheselectionandsizingofanappropriate:W

    Desalinationunit

    (includingenergystorage) Renewableenergysystem

    Pre/posttreatmentunit

    (pumps,storagetanks,etc.) Associatedmachinery

    Brinedisposalsystem

    Additionally,acostevaluationofthedesignedsystemwillbeperformedtoensurefeasibilityof

    implementationofthisdesignandtoshowthatalternativeenergycombinedwithappropriate

    smallscaledesalinationtechnologyiscostcompetitivewithlargedesalinationplantspoweredby

    onventionalsources.c

    10

  • 3. LITERATUREREVIEW

    3.1.DESALINATIONTECHNOLOGIES

    Whenwetalkaboutdesalinationtechnology,wefirstneedtodefineitasaseparationofsaline

    aterintotwomainstreams:w

    thefreshwater(

  • Figure1:Solarstillschematic(Akash,2000).

    Themajoradvantageofthebasinstillisthatitdoesnotrequireapressurizedwatersupplyto

    pumpthefeedwaterintothestill.Inaddition,itcouldbemobileandtherebyveryeasytohandle

    andmaintain.Ontheotherhand,itissusceptibletoweatherdamageandrequireslargeareasof

    landforinstallationforacommunitysizesystem.Theyhavelowoutput(12L/m2/day)(Faridet

    l,.1996).Inadditionthematerialisexpensiverelativetotheproductionrate.a

    ReverseOsmosis(RO)

    ReverseOsmosisisthemostwidelyuseddesalinationtechnologyaroundtheworld.ROinvolves

    applyinghighpressuretoforcethewatertomovefromamoreconcentratedsolutiontoaweaker

    one.Thesemipermeablemembraneallowswatertopassthrough,butblocksthepassageofthe

    bulkiersaltmolecules.Asaresult,freshwaterisaccumulatedononesideandbrineontheother.

    Themainadvantageofthissystemisthatreverseosmosisprocessisusedincaseswherewateris

    highinsalinity(from500to50,000ppm)andallowsagoodremovalofsolidsandbacteria.Onthe

    otherhand,themembraneissensitivetobiofoulingandanyexcesstotalsuspendedsolids;

    hardnessandturbidityinthewaterwillcausescalingonthesurfaceofthemembraneand

    thereforereducethequalityofwaterintheendaswellasthevolumeofwaterfiltered.Alsothe

    ystemrequiresagoodpretreatmenttoproducepotablewater(Eltawiletal,2009).s

    12

  • Electrodialysis(ED):

    Itisalesspopulartypeofmembraneseparation,developed10yearsbeforeROsystem.Itusesan

    electriccurrenttodrawdissolvedsaltsandmetalionsthroughaselectivemembrane,leaving

    behindfreshwater.Itcanbeusedfordesalinationofbrackishwateratasmall(150m3/d)or

    medium(50250m3/day)scaleandrequiresanenergyinputof0.52.5kWh/m3.8594%ofwater

    canberecoveredwithtotaldissolvedsolidscontentof140600mgTDS/L.Theenergy

    consumptionisaproportionaltotheamountofsaltsremoved,notthevolumeofwatertreated

    thereforemakingthesystemmoreefficientforlesssalinefeedwater.Inaddition,EDhasbeen

    showntobeagoodmatchforwindenergybecauseitcanhandlevariabilityinpowerinputby

    changingtheflowratethroughthemembranes.However,typicalsystemsofEDcanonlyhandle

    brackishwater(upto12,000mgTDS/L).Also,periodiccleaningofmembranesisrequiredorit

    maydevelopleaksinthestackofmembranes.Posttreatmentforbacteriaisneededtoproduce

    otablewater(Eltawiletal.,2009).p

    Nanofiltration(NF):

    NFcanbeusedasapretreatmentsystem.Itisarelativelynewmembraneseparationtechnology

    thatisbeginningtocompetedirectlywithROandEDsystems.Nanofiltrationunitscanbe

    designedwithdifferentmembranequalitiesandtypicallyhaveporessmallerthan1nanometer.

    TheadvantageofNFisthatitcanremoveorganicchemicals,herbicides,pesticides,detergents,

    andviruses.Theseabilitiesmakeitagoodpretreatmentsystemfordesalinationbutitcannot

    perateonitsownforthesameprocesssinceitisapretreatment(Diawara,2008.).o

    13

    MechanicalVaporCompression(MVC)andThermalVaporCompression(TVC):

    Vaporcompressionisanotherdistillationprocess.Aftersalinewaterisheatedbyanauxiliaryheat

    elementintheboilingchamberthegeneratedvaporsarecompressed,therebyincreasingpressure

    andtemperatureofthesteam.Thecompressedsteamisroutedbackthroughtheboilingchamber

    viaaheatexchangeronwhichthesteamcondensesandreleasesthelatentheatbacktotheboiling

    liquid,recyclingtheenergy.Thecondensationofthesteamresultsintheproductionofveryhot

    distilledwater,whichpreheatsthesalinefeedwaterenteringthesystemwhilecoolingthefinal

    productandincreasingenergyrecyclingwithinthesystem.Thissystemcanuseeithera

  • mechanicalsourceofenergy(shaftpower)orelectricalenergytorunthecompressorandthermal

    powertoheatthefeedwater.Thisprocesshaslowconsumptionofchemicals,relativelylow

    energyinputandisconsideredtobeaportabledesignwhichallowsflexibility.However,the

    systemrequiresanauxiliaryheatsourceforstartupandthecompressoritselfrequiresalotof

    aintenanceinordertooperateeconomicallyandefficiently(Eltawiletal.,2009).m

    MultiEffectDistillation(MED):

    MEDisamultistagedistillationprocessverysimilartoMVC.Thisprocessusesanexternalsteam

    supplytoheatthesalinewater.Theoperationisdoneatlowtemperatures(70oC),therebymaking

    itmoreenergyefficientthanothermultistagedistillationprocesses.Avacuumpumpisusedto

    lowerthepressuresinthevacuumchamberandtheseawaterisheateduntilitvaporizes.The

    vaporsgeneratedinonestageareusedastheheatsourceforeachsubsequentlowerpressure

    stageintheprocess.Someoftheseawatervaporcondensesandisremovedasfreshwaterduring

    eachstage.Theelectricalpowerrequirementis2.52.9kWh/m3.Thethermalpowerrequirement

    is4.56.5kWh/m3.Inadditionupto65%ofthewatercanberecoveredasfreshwaterandthe

    finalproducthaslessthan10mgTDS/L.Furthermore,theprocessrequiresminimalpre

    treatmentandlittleoperatorinput.Inaddition,heatandelectricitycanbecogeneratedto

    increaseefficiencyofproductionfortheMEDsystem.However,thiswillresultinhighenergy

    consumption,highcapitalandoperationalcostsandbecauseofthisthesystemcanonlybe

    economicallyfeasibleonalargescale.Thesystemrequiresgoodqualitymaterialtoavoid

    corrosionproblemsinthepipingandoverallsystemconfiguration(Eltawiletal.,2009).

    14

  • 3.2RENEWABLEENERGYTECHNOLOGIES

    Renewableenergytechnologiesofferanexcellentsourceofpowerforthedesalinationprocessin

    regionswherefossilfuelsareprohibitivelyexpensiveorareinconsistentlyavailable.Renewable

    energytechnologieshavesteadilybecomemoreavailable,reliable,andaffordablesincetheir

    introduction.Risingfuelpricesandconcernsaboutpollutionfromthecombustionoffossilfuels

    arealsomakingrenewableenergiesevermorecompetitiveinthemarketplace.Additionally,the

    implementationoflocalenergyresourcestopowerthedesalinationprocesscanleadtowaterand

    energyautonomyandconsequentimprovementsinsocialconditionsforthecommunityunder

    consideration(Eltawiletal.etal.,2009).Thefollowingsectioncontainsareviewofmature,

    ommerciallyavailablerenewableenergytechnologies:c

    GEOTHERMAL

    GeothermalpowerisextractedfromheatthatisstoredwithintheEarth.Geothermalenergy

    systemsareessentiallyheatpumpswhichfunctiononthetemperaturedifferencebetween

    ambientsurfacetemperaturesandthehighertemperaturesthatareprevalentdeepbelowthe

    surface.BecausetemperatureswithintheEartharerelativelystable,theseenergysystemsare

    abletoprovideacontinuousandreliablepoweroutput.Geothermalheatpumpsareusuallypart

    ofathermalpowerplant,inwhichtheextractedheatisusedtodrivevapourgenerationforsteam

    turbines.Thisarrangementmakesgeothermalenergywellsuitedforthecogenerationofheatand

    lectricity,whichgreatlyincreasestheefficiencyoftheoperation.e

    Althoughgeothermalenergygenerationishighlyefficient,applicationsarehighlylimitedby

    locationtositeswheretheheatsourceisclosetothesurfaceoftheEarthsoastominimize

    drilling,whichisveryexpensiveatgreatdepths.Inlocationswherethissourceofenergyhasbeen

    harnessed,MEDunitshavebeendeterminedtobethebestdesalinationtechnologymatch,

    althoughothersarepossible,becauseMEDunitsrequirethedirectandcontinuoussourceof

    hermalenergythatgeothermalenergysystemscanreliablyprovide(Eltawiletal.,2009).t

    15

  • Figure2belowshowsallofthepotentialdesalinationtechnologycombinationsforgeothermal

    energy.

    SOLARGeographicallyspeaking,thereareoftenabundantsolarresourcesinregionswithaneedfor

    desalinationinstallations.Thisisbecausearidregionswithfewwaterresourcestendtobecloser

    otheequatorwhereincidentsolarradiationisthehighestonthesurfaceoftheEarth.t

    Theoutputofsolarenergysystemstendstoberelativelyunpredictableandintermittentand

    becauseofthiscondition,typicallyrequiresanenergystorageunitinordertoensurecontinuous

    perationofsolarenergydrivenmachines.o

    Solarenergytechnologycanbedividedintotwogeneralcategories:solarthermalandsolar

    lectric.e

    16

    Solarthermalreferstothecollectionofsolarenergyasheat.Lowandmediumtemperature

    systemsareflatplatecollectorswithalargenumberoftubesencasedinatransparentplastic

    enclosure.Thetransparentplasticcreatesagreenhouseeffectandthetrappedheatisthen

    transferredtotheworkingfluidwhichhasahighheatcapacity.Hightemperaturesystemsuse

    reflectorstoconcentratesolarenergyinordertogeneratewatervapourstopowerasteam

    turbine.Whilethesesystemsarehighlyefficient,theapplicationofconcentratedsolarpowerfor

    electricitygenerationissomewhatrestrictedtolargescaleinstallations.Thesesystemscanbe

    usedasadirectsourceofthermalenergyfordistillationprocesses.Thermalenergycanbestored

    inlargemassesofconcrete,ceramics,orothersuchmedia(Eltawiletal.,2009).

  • Solarelectricreferstothegenerationofelectricityfromsolarenergy.Althoughsolarelectric

    powerhasahighercostperkWh(seeTable1),ithasbeenrepeatedlyproventhatitiswellmated

    tomembranedistillationprocessessuchasROandED.Thereasonforthisisbecausetheyrequire

    alotlesspowerthanotherdesalinationtechnologiesandalsocanhandlesomevariabilityin

    powerbyvaryingflowrateacrossthemembrane(AbuJabaletal.,2001.,Abdallahetal.,2005.,

    Hasnainetal.,1998.,Hrayshat,2008.,Mahmoud,2001.,Mohsenetal.,2001).Electricalenergy

    generatedfromsolarphotovoltaicarrayscanbereliablystoredinbatteries(Eltawiletal.,2009).

    Figure3belowshowsallofthepotentialdesalinationtechnologycombinationsforsolarenergy.

    WINDWindenergyresourcesarehighlylocationdependentandaretypicallyabundantonislandsandin

    coastalandmountainousareas.Likesolarenergy,theoutputofwindturbinesisalsointermittent

    andvariable.Windenergycanbeuseddirectlyasmechanical(shaft)powerorusedtogenerate

    lectricity,whichcanbestoredinbatteries.e

    MechanicalpowerfromwindenergyhasbeenshowntosuccessfullyrunthecompressorsinaRed

    Seasitedvapourcompressiondesalinationprocess(Karameldin,2002).Electricalpowerfrom

    windcanbeusedtopowerboththecompressorandtheheatingelementinthevapor

    compressionprocessas,torunthepumpinthereverseosmosisprocess(Eltawiletal.,2009).It

    asalsobeensuccessfullymatedtoanelectrodialysisdesalinationunit(Veza,2001).h

    17

  • Figure4belowshowsallofthepotentialdesalinationtechnologycombinationsforwindenergy.

    Table1:Comparisonofenergycostsfromvarioussources(Eltawiletal.etal.,2009).

    Technology AvgCurrentcost UScents/KWh)( WindElectricity

    onshore 4offshore 8

    SolarElectricPV 5 0SolarThermal 1 5GeothermalEnergy 6ElectricityGridfossilfuels

    Average 9RuralElectrification 52.5

    NuclearPower 5NaturalGas 3

    Coal 4

    18

  • 19

    SlowSandFilter

    Beforeenteringthedesalinationsystem,therawwaterwillpassthruaslowsandfilteranda

    cartridgefiltertoremovesurplusofturbidity(bybiologicalaction)andsuspendedsolids,which

    maycauseproblemsinpumpoperationandinstrumentationiftheyentertheROsystem.In

    addition,theymayobstructtheflowchannelordepositonthemembranesurfacescausing

    alterationinthequalityofwaterandsalinity.Thewaterisfilteredbythesanditselfandbythe

    layerofmicroorganismsthatdevelopsontopofthesand.First,alayerofdirt,debris,and

    microorganismsbuildsuponthetopofthesand.Slowsandfiltersworkthroughtheformationof

    agelatinouslayerorbiofilminthetopfewmillimetresofthefinesandlayer.Thebiofilmis

    formedinthefirst1020daysofoperation(CentreforAffordableWaterandSanitation

    Technology,2007).Thecomplexbiologicalsurfacelayerknownasthebiofilmconsistsof

    3.3PREANDPOSTTREATMENTTECHNOLOGIES

    PreTreatment

    FortheprotectionoftheeffectivityandlifespanofourReverseOsmosis(RO)installation,a

    sufficientpretreatmentisrequired.Itissaidthatanappropriateselectionofpretreatment

    methodsforfeedwaterwillimproveproductivityandextendthelifespanofthesystemby

    preventingorminimizingbiofouling,scalingandmembraneplugging.

    Toperformacontinuousandreliablepretreatmentofthefeedwateraspecialapproachisused.A

    pretreatmentthatisnotpropertotheinstallationmaycauseasystemoverload.Whenthisoccurs

    thesystempartsneedcleaningmuchmoreoftentorestoreproductivityandsaltretention.

    Cleaningcosts,systemperformanceandstandstilltimeareverysignificantinthatsituation.

    Thetypeofpretreatmentsystemthatisusedsignificantlydependsonfeedwaterquality.

    Consequentially,sufficientfeedwaterpretreatmentisdependenton:

    Thesourceofthefeedwater

    Thecompositionofthefeedwater

    Thefunctionofthefeedwater

    bacteria,fungi,protozoa,rotiferaandarangeofaquaticinsectlarvae.Thewaterproducedfroma

  • 2CartridgeFilters

    Asforthefilteringapplications,thechoiceofusingthecartridgefilterisacriticalonesinceitisa

    sedimentfilter,thatistosayitreducetheamountofsedimentstransportedbythefluidtrough

    filtration.Thechoiceofcartridgefilterwilldependontheapplication.Thecartridgefiltersare

    preferableforsystemswithlowcontamination.Thecartridgefiltersasillustratedinfigure3are

    0

    wellmanagedslowsandfiltercanbeofexceptionallygoodqualitywith9099%bacterial

    eduction(NationalDrinkingWaterClearinghouse,2000).r

    Theadvantageofusingtheslowsandfilteristhatitdoesnotrequireanyuseofflocculantsor

    chemicalstoworkeffectively.Theslowsandfilterscanproduceveryhighqualitywaterfreefrom

    pathogens,tasteandodourwithouttheneedforchemicals.Passingtherawwaterthroughaslow

    sandfilterremovestheflocsandtheparticlestrappedwithin,reducingthenumbersofbacteria

    andremovingmostofthesolids.Afterthesandlayer,thewaterwillmovethruamassofgravel

    andperforatedpipesand/oranyloncurtainoragoodgeotextilelinerbelowthesand,limiting

    theinfiltrationofthesandintotheROfeedpump.Asasolutionthesandfiltermayincludealayer

    ofactiv tedcarbona

    belowthegravellayoutinordertoremovetasteandodour.

    MaintenanceoftheSandFilter

    Sandfiltersbecomecloggedwithflocafteraperiodinusesotheyshouldbebackwashedor

    pressurewashedtoremovethefloc.Inadequatefiltermaintenancehasbeenthecauseof

    occasionaldrinkingwatercontamination.Thereby,maintenanceoftheslowsandfilterconsistsof

    gatheringorrakingthesandperiodicallyandcleaningthefilterbyremovingthetoptwoinchesof

    sandfromthefiltersurface.Afterafewcleanings,newsandmustbeaddedtoreplacethe

    removedsand.Cleaningthefilterremovesthebiofilmandaftercleaningthefilter,thenew

    filtrationprocessmustbeoperatedfortwoweeks,withthefilteredwatersenttowaste,toallow

    biofilmtorebuilditself.Asaresult,treatmentplantsmusthavetwoslowsandfiltersfor

    continuousoperation.Slowsandfiltersareveryreliablefilterswhichdonotusuallyrequire

    coagulation/flocculationbeforefiltration.However,waterpassesthroughtheslowsandfilter

    veryslowly.Asaresult,largelandareasmustbedevotedtofilterswhenslowsandfiltersarepart

    ofatreatmentplant.Acarefulperiodicinspectionoffiltersandpipelinescanalsobeuseful.

  • alsocalledsurfacefilters.Theywillworkbestforourdesignsinceithasmoresurfaceareatofilter

    sedimentofverysmallsizemainlylessthan5microns.Cartridgefiltersarenormallydesignedto

    bedisposable,thereforewhentheyarecloggedtheywillneedtobereplacedinordertomaximize

    igherflowsandhaveabetterdirtholdingcapacity.h

    PostTreatment

    OncethewaterhasbeenfilteredbythepretreatmentmethodandfurtherbytheReverseosmosis

    system,therearetwomethodsofposttreatmentforourproject.Firstwecouldaddchlorinetothe

    productwaterinordertoeliminateanyresidualbacteriathathavebypassedthedesalination

    processintothefinalproduct.ThesecondposttreatmentpossibleistheuseofUltravioletlight.

    Disinfectionmaybebymeansofultravioletradiation,usingUVlampsdirectlyontheproduct

    waterforthesamepurposeofeliminatingthebacteria.InadditiontotheUltravioletradiation

    method,wecouldusethesupplementalelectricitythathasbeengeneratedbyourPVtofeedthe

    UVlights.Furthermore,afterchlorination,theproblemofthedesalinatedwaterbeingvery

    corrosiveonthecementorconcretelinedsurfaces,canbefixedbytheuseofapHadjustment

    chemicalormineralsuchaslimewillbeimportantinordertostabilize,toprotectdownstream

    pipelinesandstoragestanksfromcorrosion.Limingmaterialisusedagainstcorrosionbutalsoto

    remineralisethetreatedwaterinordertomeetthepotablewater.TheROpermeatewaterwillbe

    storedinanintermediatetank.Thispotablewaterwillbethenpumpedtoanothercartridgefilter

    inordertoeliminateanyremainingsediments.Thepurewaterflowsfromthemodulestoa

    toragetank.s

    21

  • .4 BRINEDISPOSALMETHODS3

    Inanytypeofdesalinationtechnologies,thereisaproductionofconcentratebrine(the

    concentratestreamwhichcontainsahighpercentageofsaltsanddissolvedminerals.).Inmost

    cases,desalinationplantsdischargetheirbrinecontentbackintotheseaiftheyarelocatedin

    coastalregionsorundergroundiftheyarelocatedinland.Asweknow,reductionsinwater

    qualityandquantityhaveseriousnegativeimpactsonecosystems.Duetothehighlevelofsalinity

    anditstotalalkalinity,brinecanalterthetemperaturewithofitssurroundingsbothintheseaor

    groundwaterifnotdisposedofproperly.Brackishwaterreverseosmosisconcentrate,if

    dischargedtosurfacewater,canchangethesalinityofthereceivingwater.Thechangeinsalinity

    canchangetheconcentrationofdissolvedoxygeninthewaterandnegativelyaffectaquaticlife;

    thestandardlimitforsurfacewaterdischargeisasalinitydifferenceoflessthan10%.These

    impactscouldbeimportantintermsoftheinfluenceithasonthemarineorganisms,suchasthe

    developmentandsurvivaloflarva.Themajorconcernoftheseimpactssurroundstheoutfallof

    hebrinedischargebecauseofitsphysicalandchemicalfeatures(Mickley,1993).t

    Therefore,theissueofutmostimportanceiseliminatingthesepossiblenegativeimpactsonthe

    environmentbythedevelopmentofcosteffectivebrinedisposalsystems,whichconformto

    regionalandfederalenvironmentalconstraints.Themajorstrategiesforbrinedisposalatinland

    sitesarereducedtothreegeneralcategories;1)DeepWellinjection2)SolarPonds3)Evaporation

    Ponds.Othersystemssuchasirrigationofsalttolerantplants(halophyticcrops),andrecoveryof

    inorganicsaltsforpotentialcommercialvaluehasalsobeensuggested,however,theyarecostlyto

    implementanddonotdemonstrateeconomicviability.Theuseofsalinewaterforcropirrigation

    alsoaddssalttothesoilandtothelocalgroundwateraquifers(Mickley,1993).Buildupofsaltin

    thesoilcanaffectfuturecropgrowth,whilethegroundwaterwillslowlyincreaseinsalinityover

    time.Inaddition,highboronconcentrationsintheirrigationbrinewatercancauseplantdamage

    (Nadav,2005).

    Asaresultthisreportwillfocusonareviewofthethreetechnologicalfeaturesforhandlingthe

    volumeofwastebrineandoneofwhichwillbemostcosteffectiveandfeasibleforourproject.

    22

  • DeepWellInjection

    Thismethodisappliedworldwidefordisposalforlandbasedindustrialmunicipalandliquid

    hazardouswastes.Injectionwellsmayvaryindepthfromfewhundredfeettoseveralthousand

    feetdependingonthegeologicalsitelocation.Thismethodisusedasamodelforanyconcentrate

    whereinadequatewastesolutiontransportandconfinementcouldresultincontaminationof

    surfaceandgroundwaterresources.Deepinjectionwellscanbeusedtoinjectliquidwastesin

    poroussubsurfacerockformations.Siteselectionisdependentupongeologicalandhydro

    geologicalconditions.Theuseofthistechnologyisnotfeasibleinareasvulnerabletoearthquakes

    orregionswithmineralresourcessincethiscouldcausedamagetothewellandsubsequently

    resultingroundwatercontamination.Furthermore,thismethodisonlycosteffectivefordisposal

    oflargevolumesofprocessedfluid(Mickley,1993).Sinceourdesignprojectinvolvessmallscale

    productionoffreshwater,thebrinevolumefordisposalwouldbesmallandtherebyrenderthe

    deepwellinjectionmethodnotcosteffectiveandwhileriskingaquifercontamination.

    SolarPonds

    Solarpondsaresalinitygradientpondswhicharedevelopedasanintegratedsystemfor

    membranedesalinationcoupledwithbrinedisposal.Thistechnologyproduceselectricityusing

    brineasamainconstituent.Thesalinitygradientsolarpondisanintegratedcollectionand

    storagedeviceofsolarthermalenergy.Theprocessstartswhenlargequantitiesofsaltare

    dissolvedinthehotbottomlayerofthebodyofwater,thiswillmakethislayerofwatertoodense

    toriseuptothesurfaceandcool.Generallytherearethreemainlayersinasolarpond.Thetop

    layeriscoldandhaslowsaltcontent.Thebottomlayerishotandverysalty.Separatingthesetwo

    layersistheimportantgradientzonewheresaltcontentincreaseswithdepthandwherewaterin

    thegradientcannotriseduetotheabovelighterwaterlayerwhichcontainslesssalt.Thewater

    belowthegradientzoneisheavierbecauseofitsvolumeofsaltcontentwhichislarge.Therefore,

    thesteadygradientzonerestrainsconvectionandactsasatransparentinsulatorwhichpermits

    sunlighttobetrappedinthehotbottomlayer.Thehotbottomlayerheatcouldbethenwithdrawn

    orstoredforlateruseinelectricitygeneration.However,tohaveeffectiveelectricitygeneration,

    olarpondsrequire:s

    23

  • largevolumesofbrine,aswellasanadequatesourceof'fresher'water

    cheap,flatland,oflowpermeability,andhighthermalandstructuralstability

    pondarea(minimumsizeonehectareandmaximumoftenhectares)(Ahmedetal.,2001)

    Onceagain,sincethismethodrequireslargevolumesofbrinedisposalwecannotimplementthis

    techniqueforourdesignprojectsincewewillbedealingwithasmallscaledesalinationplant

    whichproduceslowbrineeffluentanddisposesofarelativelysmalllandareafortheinstallation

    fthebrinedisposalequipmentandtechnology.o

    Figure5:Saltgradientnonconvectivesolarpond(Ahmedetal.,2001).

    24

  • EvaporationPonds

    Brinedisposalisnormallyseenasamajorissueintheengineeringdesignofanydesalination

    facility.Evaporationpondshavebeenusedoverthecenturiestoremovewaterfromsaline

    solution.Thisrelativelyeasytoconstructtechnologyrequireslowmaintenanceaswellaslittle

    operatorattentioncomparedtomechanicalsystemssincetheonlymechanicalequipmentneeded

    isthemechanicalpumptoconveythewastewatertothepond.Atthistimemethodisthemost

    idespreadbrinedisposaltechniqueforinlandbaseddesalinationfacilities(Mickley,1993).w

    Evaporationpondsaredesignedtoprocesssmalldesalinationbrineeffluent(lessthan5million

    gallonsperday)andgenerallyrestrictedtoaridclimaticregionswhichhavehighevaporation

    ratesandavailabilityoflandatlowcost.Evaporationpondsaredesignedtoconcentratethe

    receivedeffluentandreduceitsvolumethroughevaporation.Anumberofsmallpondsare

    constructedandconnectedbyapipeline.Eachpondrequiresalinerofclayorsynthetic

    membranessuchasPVCorHypaloninordertopreventanyseepageandcontaminationofthe

    groundwateraquifers.Unlinedpondslocatedinlightsoilscanleakandresultinthemovementof

    saltstothegroundwater.Tobesufficientforthedisposalofthebrinesolution,ourdesign

    implementationwillconsidertwoadjacentsmallevaporationpondsconnectedbyapipeline

    located30cmabovethebedofthepond.Inaddition,byconcentratingthebrine,evaporation

    basinsoffertheopportunitytodevelopsystemssuchasaquaculture,brineshrimp,betacarotene

    roduction(Ahmed,2001).p

    25

  • 4. DESIGNMETHODOLOGY

    4.1.DESCRIPTIONOFSITEANDCONTEXT

    Jordanspotentialwaterresourcesareestimatedtoberoughly1000MCMor1200MCMifthe

    potentialforrecycledwastewatersistakenintoaccount.Ofthisvalue,750MCMcanbe

    sustainablysourcedfromrenewablegroundandsurfacewater.Anadditional143MCMcanbe

    suppliedfromthenonrenewablefossilwatersreferencedearlier.Ithasalsobeendetermined

    that50MCMoffreshwatercanbesourcedfromthedesalinationofbrackishgroundandspring

    waterthatisavailablearoundthecountry.Althoughthebrackishspringwatersourcesare

    scatteredandaredifficulttoexploitonalargescale,theywillbeabletosupplydesaltedwaterfor

    mall,remotecommunitiesbyutilizingsolarandorwindenergy(Mohsen,2007).s

    Amultiobjectiveanalysiswasperformedtoevaluatetherelativeimportanceofdifferentnon

    conventionalsourcesofwaterforJordananditsresults(seefigure)showthatdesalinationisthe

    mostfeasiblebasedoneconomic,technical,availability,reliability,andenvironmentalfactors

    (Jaberetal.,2001).Morespecifically,thedesalinationofbrackishwaterisfarmoreeconomical

    thanseawateronasmallscale.Sinceenergyconsumptionintheprocessisdirectlyrelatedtothe

    operatingpressures,andoperatingpressureisdirectlyrelatedtotheconcentrationofdissolved

    solidsinthefeedwater,onecanconcludethatdesalinatingbrackishwater(110g/LTDS)as

    comparedtoseawater(35g/LTDS)wouldrequirelessenergyandtheproductwouldhavea

    essercost(Mohsen,2007).l

    26

    ThoughJordanissurroundedbymanyoilrichnationsithasveryfewofitsownfossilfuel

    reservesandmustthereforedevelopalternativesourcesofenergyforitsgrowingneeds.Amulti

    criteriaanalysiswasperformedinordertoanalysethefeasibilityofusingdifferentnon

    conventionalenergysourcestopowerdesalinationprocessesinJordan,findingthatsolarenergy

    maybeeconomicallyusedtoproducewaterfordomesticusageasbasedoncriteriaof

    environmentalsustainability(Akashet.al,1997).Averageannualsolarradiationonahorizontal

    surfaceinJordanhasbeenfoundtorangefrom57kWh/m2/daydependingonlocation,makingit

    oneoftherichestcountriesintheworldintermsofsolarresources(Abdallah,2005).Although

  • waterdemandishighestduringthedrysummermonths,thisisalsothetimeperiodwiththe

    highestratesofsolarradiationandsunshineduration(seeFigures6and7),furthersolidifyingthe

    ecisiontoutilizesolarpowerfordesalinationofbrackishwater.d

    Figure6:MeanmonthlyvariationoftherecordedglobalsolarradiationforJordan,1994

    2003(Hrayshat,2009).

    Figure7:MeanmonthlyvariationoftherecordedsunshinedurationforJordan,19942003

    Hryashat,2009). (

    27

  • 4.2 SELECTIONOFTECHNOLOGIES

    4.2.1. RENEWABLEENERGYSYSTEM

    Anarrayofsolarphotovoltaicunitsisthechosensourceofrenewablepowerforthedesalination

    processinthisdesign.Thistechnologyhasbeenonthemarketforaverylongtimeandcurrent

    efficienciesarehigherthanever.Innovationinthesolarphotovoltaicindustryhasleadto

    developmentofspecialcoatingswhichincreaseresistancetodamagefromsandstormswhich

    akesthistechnologyevermoresuitableforapplicationsinthedesert.m

    ThepotentialofphotovoltaicenergygenerationhasbeenwellstudiedinJordanandprecisedata

    isavailablefromalongtermstudy(19942003)of24locationsaroundthecountry(Hrayshat,

    2008(2)).DuetotheincredibleabundanceofsolarresourcesinJordan,utilizingthisresourceis

    hemostlogicalandcosteffectiveoption.t

    4.2.2. DESALINATIONUNIT

    Overthelasttwentyyearsdesalinationusingmembranetechnologyhasbeenestablishedasa

    flexible,lowcostsolutiontotheproductionofpotablewaterfrombrackishgroundwater.The

    combinationofreverseosmosiswithasolarphotovoltaicenergysourceisthemostpopular

    methodfordesalinationworldwide(seeFigure8).BrackishwaterROistypicallythelowest

    capitalinvestmentandoperatingcostsolutionformostapplicationsgivenitsrelativelylow

    overallenergyconsumptionandeaseofmanufactureandconstruction.Accordingtofactorssuch

    astotalpowerconsumption,capitalcost,reliabilityprocess,andavailability.Table2givesusan

    deaaboutwhichprocessisbestforoursituation.i

    28

  • Table2:DesalinationTechnologiesOverview(Eltawiletal.2009)

    Technology

    Capital

    Cost ReliabilityAvailability

    Water

    Specific

    Cost

    TotalAverage

    Energy

    Consumption Maintenance

    ($/MGD) % $ (k 3)Wh/m

    MVC 5 Medium 96 Moderate 13.25 high

    MED 4.5 Medium 96 Low 8.2 medium

    RO 4 High 96 Low 1.75 low

    Figure8:Renewableenergydesalinationcombinationsworldwide(Eltawiletal.,2009).

    29

  • BrackishWaterReverseOsmosis(BWRO)

    BrackishwaterareanywatersourceswithTDSbetween1000and15000mg/L.Brackishwater

    cannotbeconsumedbyusdirectlyduetoitshighsalinity.AccordingtoWorldHealthOrganization

    (WHO),waterwithsalinitybelow500mg/Lisacceptableasdrinkingwater(Alghouletal.,2009).

    WithmuchresearchdoneonBWRO,ithasbeenestablishedtobethemosteconomicaland

    reliableprocessascomparedtotheMVCandtheMED.BWROsystemswhichhavebeentestedin

    realsituationshaveimprovedrecoverypercentageforsmallscaledesalinationoperations.When

    effectivelyoperatingaBWROsystem,thenthereductionofenergyconsumptionisconsiderable

    andthiscouldeventuallybereducedtolessthan1.75kWh/m3,whichislowerthanthetotal

    energyconsumptionofMVCandMSF.Furthermore,reverseosmosisrequireslessmaintenance

    sincethereisnoneedtocontroltemperatureatallstagesoftheprocesssuchasinMED(Afonsoet

    al.,2003).Fromthis,weconcludethatourmainchoiceofdesalinationwouldbereverseosmosis

    sincealltheimportantfactorsareacceptableforthereverseosmosiscomparedtotheothertype

    ftechnologies.o

    30

  • 4.2.3PRE/POSTTREATMENTUNIT

    MuchresearchhasbeendonetostudythewaterqualityatnumerouslocationsinJordan

    (Hryashat,2008(1).,Jaberet.al,2001.,Mohsen,2007.).Thisresearchwillbereferencedwhen

    makingdecisionsrelatedtothecompositionofthefeedwatersuchasselectionofpreand/orpost

    reatmentunitst

    Whenthesourceofthefeedwaterthatneedstreatmentisspecified,itwillbeanimportantstep

    forthedesignofapretreatmentsystemandtheentirereverseosmosissystem,becausethiswill

    determinethetypeandsizeofthepretreatment.Thelimitingfactorforthetreatmentofbrackish

    waterwithareverseosmosissystemismainlyitschemicalnature.Thismeansprecipitationand

    scalingcausedbycalciumcarbonateorsulphates.Thechemicalcompositionofbrackishwaters

    variesalotandisverylocationspecific.Toproduceanacceptableprocessdesign,wewillhaveto

    relyonaveryaccuratewateranalysistobecarriedoutatourspecificlocation.

    4.2.4 BRINEDISPOSALUNIT

    Theevaporationpondhasbeenchosenastheoptimalmethodofbrinedisposalforarurallocation

    inJordan.Thismethodofinlandbrinedisposalrequirestheleastcapitalinvestmentandis

    appropriatefortreatingsmallerscaledesalinationplanteffluent.Awayfromthecities,largeareas

    oflandshouldbeavailableatlowcost,makingthisanappropriateselection.Also,thepossibilityof

    aquacultureandtherevenuesassociatedwithsaltproductionmakethisanenticingsolution.

    Fromthiswecanconcludethatthismethodcouldbesuitableforourdesignreportforaproper

    brinedisposalforasmallscaledesalinationplantsinceevaporationpondsremaininmanycases

    themostcosteffectivemeansofsalinewaterdisposal.

    31

  • 4.3DESIGNAPPROACH

    AbasicschematicofaROdesalinationplantisshowninFigure10.Itisimportanttonotethattwo

    ROunitswillberequired,andthereforetwoidenticalinverters,twohighpressurepumps,and

    twoofeachtypeofvalverequired.Thisisessentialtothedesignbecauseifoneoftheunitsis

    undermaintenanceorrepair,thebackupunitwillcontinuetoproducewater.Thisdesignensures

    areliableproductionoffreshwaterwillbeensured.

    Thesystemicdesignofarenewableenergypowereddesalinationunitfollowstheflowchartas

    seeninFigure9.Thefirststepistoidentifythequantityoffreshwaterneededbythecommunity

    inconsiderationforthisproject.Itisnecessarytocommunicatewiththecommunityweare

    intendingtohelpwiththisprojectinordertofindoutwhattheirwaterdemandsareandwhatthe

    enduseofthedesalinatedwaterwillbe.Oncethecommunitysdemandisdetermined,the

    capacityofthedesalinationunitwillbesizedtomatch.Therenewableenergysystemcanthenbe

    designedbasedontheenergydemandfromthedesalinationunitandtheassociatedpre/post

    reatmentsaswellasthepumpsneededtoruntheprocess.t

    oappropriatelysizetheenergysystem,wemustfirstdeterminetheloads.T

    SizingtheBrackishWaterPumpingSystem

    Afterthedesiredoutputofthedesalinationplantisdetermined,thevolumeoffeedwater

    necessarycanbedeterminedbasedonthewaterrecoveryefficiencyoftheselectedsystem.Once

    hedesiredflowrateofthepumpisdetermined,thehydraulicenergyrequiredwillbe:t

    32

  • T

    hedailyrequiredenergyfromthePVgeneratorwillbe:

    Oncerequiredenergy(kWh/day)isdetermined,thepeakpowerrequiredfromthePVgenerator

    iscalculatedas(withasafetyfactorof1.25):

    ThePeakSunshineHours(PSH)iscalculatedas:

    DeterminingROEnergy equirements

    Based on data from the manufacturer of the RO unit, electrical consumption per unit water

    producedcanbedeterminedasafunctionoffeedwatercomposition.Theenergyrequiredforthe

    ROunitwillbe:

    R

    The peak power required by the RO unit can then be determined, taking into account a safety

    factorof1.25foreachofthetwounits:

    33

    The power required by the pumps and the RO unit can then be added together in order to

    determinethenecessarygenerationcapacityofthesolarPVarray.

  • SizingtheEnergyStorageBatteryBlock

    In order tomake sure that energy continues to flow to theRO units evenwhen the sun is not

    shining,thebatterycapacityneedstobesizedasfollows:

    Onceallofthesecalculationsareperformed,thepairofinvertersandthebatterychargeregulator

    willbesizedinordertosafeguardtheenergysystemandtheROunitfromfluctuationsinenergy

    roductioninthesolarPVarray.p

    igure9:RESdesalinationdesignalgorithm(Eltawiletal.et.Al,2009).F

    34

  • igure10:BlockdiagramoftheproposedPVpoweredBWROdesalinationplant(Mahmoud,003).F2

    SolarGenerator;2,WellPump;3,SandFilter;4,CartridgeFilter;5,BatteryBlock;6,HighPressure1,P1

    umps;7,ROModules;8,RegulatingValves;9,StartingValves;10,ProductWaterStorage;11,ProductWaterPump;2,DC/AC3PhaseInverter.

    DesignoftheEvaporationPond

    Thepropersizingofanevaporationpondwilldependonaccuratecalculationoftheannual

    evaporationrate.Asweknow,evaporationfunctionsbyshiftingliquidwaterinthepondtowater

    vapourintheatmosphereabovethespecificponditself.Theevaporationratewilldeterminethe

    surfacearearequiredwhilethecalculationofdepthisbasedonwaterstorage,andstorage

    capacityforthesalt.Salinityofthewaterinfluencestherateofevaporation;theyareindirectly

    proportionaltoeachother.Asthesalinityincreases,evaporationratesdecreases.Inorderto

    maximizetherateofevaporation,therecommendedpondrangingdepthisoptimalfrom25to45

    cm.Thisoptimaldepthmustberespectedsinceveryshallowevaporationpondscanbeeasily

    subjectedtodryingandcrackingoftheliners.Asweknowtherateofevaporationvariesfrom

    locationtolocation,thereforeaccurateevaporationdataarerequiredfordesigninganefficient

    evaporationpond.Itisnecessarytoensurethattheaverageannualevaporationdepthexceedsthe

    depthofwaterthatwouldhavetobestoredinthepond(Ahmedetal,2001).

    35

  • Accordingtothedesignandmainte ofevaporationpondsproposedbyAhme

    pondopensurfacearea(A)andmi nbeestimatedfrom:

    nance

    nimumponddepth(d)ca

    detal,the

    A=V*f1/(0.7*Eave)

    Dmin=0.2+Eave*f2

    WhereAistheopensurfaceareaofthepond(m2),Visthevolumeofrejectedwater(m3/d),

    Eaveistheaverageevaporationrate(m/d)whichcanbedeterminedusingthepanevaporation

    ratemethod.F1isanempiricalsafetyfactortoallowforlowersthanaverageevaporationrates,

    Dministheminimumdepth(m)andf2isafactorthatincorporatesthelengthofthewinterseason.

    Thevalueof0.7intheareaequationrepresentstheevaporationratioformultiplyingcalculated

    solarevaporationratetoincorporatetheeffectofsalinity.Thevalueof0.2minthedepthequation

    isthefreeboardforrainfallintensity,durationaswellaswindspeedactionlikelytobeproduced

    inthepond.Inotherwordsthefreeboardisdefinedasthedepthabovethenormalrejectwater

    surface,sothatduringlowevaporationperiods,willnotcauserejectionofwatertospilloutofthe

    pond.Thedesignoftheevaporationpondconsiderscarefullythesurfacearea,depthand

    freeboardofsuchinstallation,sincethesearethefactorsthataredeterminedbytheratesof

    concentratedischargerelativetosurfaceevaporationrates.Therefore,itisclearthatthearea

    eededisdirectlyproportionaltovolumeofrejectwaterandinverselyproportionaltothe

    vapor tionrate(Ahmedetal,2001).

    n

    e a

    36

    Liners

    Linersarethemostimportantaspectofanevaporationpond,astheyshouldbemechanically

    strongtowithstandstressduringsaltcleaningandalsobeimpermeable.Theevaporationpond

    linersneedtobeinstalledinaccordancewithmanufacturersinstructions.Sealingofthelinersis

    critical,especiallyalongjointsandadjacentsectionsoftheliner,inordertoeliminatepond

    leakageandsubsequentaquifercontamination.Therefore,doubleliningofpolyethyleneorother

    imperviouspolymericsheetsorliningsisstronglyrecommendedwithleakagesensingprobes

    installedbetweenlayersofpondlining.Itisofutmostimportancetohavecarefulenvironmental

    monitoringofthepotentialpondleakage,sinceavarietyoftoxicchemicalscanbeproducedin

    desalinationplantoperationthatincludeschemicalsusedinmembranecleaningandpre

    treatmentthatcouldcausemajorpotentialrisksforthecontaminationofthegroundwater

    quifer(Ahmedetal.,2001).a

  • ConstructionLocation

    Thebasinofthepondcanbeanaturalbasinfromadepressionintheearthsurfacesuchasasaline

    lake,ordrynaturaldepressions.Also,amodifiednaturaldepressionorconstructedbasinwhich

    couldbeexcavatedonlocationmaybeconsideredasanoption.Thedesignofthisprojectbasinis

    consideredtobeasmallmanageablepond.Thesmallscalepondisadvantageousespeciallyin

    windyconditionswherewindcouldnotdamagethetopsurfaceoftheembankmentorleveeand

    thereforethepondwouldlessenthemaintenancecosts.Inordertodissipatewinddamageonthe

    pond,oneneedstoremovethetopsoilwherethebankistobelocatedandthenthelengthofthe

    pondshouldbeplacedatrightanglestothepredominantdirectionofwind.Again,suitablesite

    ocationisveryimportant.Basinslocatedinnonheavysoilswillseepoutandasconsequencewilll

    inducethemovementofsaltstothegroundwater(Ahmedetal.,2001).

    Banksofthebasinshouldbe1minheightand2.4minimumwideatthecresttoallowforthe

    movementoflightvehiclesinandoutofthepond.Inaddition,inordertolessenbankerosion,the

    insideslopeisrecommendedtobe1:5slopeinordertoabsorbmostofthewaveenergy,The

    outsidebankcanbeconstructedata1:2slope.Furthermore,usingasheepsfootroller,thebanks

    arecompactedduringtheconstructionoperation.Inordertohaveanevenspreadofwaterandan

    increaseinevaporation,laserlevellingofthebedisrequired.Asanadditionalprecautioninorder

    tocontrollateralseepage,asmalldiameterinterceptionwellcouldbeemployedalongthe

    erimeterofthepoolarea,fromwhichtheeffluentwouldbepumpedbackinthebasin(Ahmedet

    l.,2001).

    p

    a

    37

  • 5. EXPECTEDRESULTS

    Theresultsthatwillbeproducedattheendofthedesignphaseareasfollows:

    1) SystemdesignofabrackishwaterdesalinationfacilityforaremotecommunityinJordan.

    Componentswillincludearenewableenergysystem,adesalinationunit,preand/orpost

    treatmentunitsifnecessary,abrinedisposalsystem,aswellasalloftheassociatedpumps

    ndstoragetanks.Manufacturersandmaterialswillbechosenandeachcomponentwillbe

    a

    sizedaccordingtotheneedsofthefacility.

    2) Acostevaluationforthepurchase,installation,operation,andmaintenanceofthesystem

    willbeperformedinordertodeterminetheunitcostofproductwater.Theeconomic

    analysiswillincludeacomparisonofprojectedwaterproductioncostsforthisspecific

    systemwithknowncostsfordesalinationplantsofsimilarandlargerscalepoweredby

    bothconventionalandrenewableenergies.Savingsfromeliminationoftransportation

    costsandpotentialincreasesofincomefromlargerirrigationcapacitiesandimproved

    personalhealthofcommunitymemberswillalsobetakenintoaccount.

    38

  • 6. TIMEFRAME

    Itisexpectedthatthedesignphasewillrequireapproximately180hoursoftotalworkbythe

    twoengineersinvolvedwiththisprojectinordertoproducethedeliverablesoutlinedinthe

    ExpectedResultsandTimeFramesectionsofthisreport.Aswithanyprojectunexpected

    tasksandchallengesmayarisethroughoutthedesignprocessandincreasetheamountof

    hourscurrentlyallocated.

    7.

    39

    COSTEVALUATION

    Althoughtheengineeringteamperformingthesystemdesignwillnotbecompensated

    monetarilyfortheirworkonthisproject,acomparablejobwouldbeperformedbyjunior

    engineerseachearningasalaryof$25/hr.Atthisrate,thecostofacompleteddesignwould

    amounttoatotalof$4,500.Itisprobablethataconsultingengineerwouldneedtobehiredto

    reviewtheworkofthejuniorengineersfortechnicalaccuracy.Weestimatetheconsulting

    engineerwouldtakeapproximately5hourstoperformanevaluationandsuggest

    modifications.Atarateof$100/hr,thecostofhiringaconsultantwouldbe$500,thereby

    ofsystemdesignto$5000.bringingthetotalcost

  • 8.CONCLUSION

    TheKingdomofJordanisacountryinwhichthedesalinationofbrackishwaterhasbeen

    determinedtohavethegreatestpotentialtoalleviatethecurrentconditionofwaterscarcity

    (Jaberetal.,2001).BecausetheproblemissosevereinJordan,wehaveelectedtocompletethe

    systemdesignforasmallscaledesalinationprojectforaruralcommunityinthiscountry.

    Althoughthepriceofdesalinatedwaterincreaseswithsmallerscaleprojects,theneedfor

    decentralizedwatertreatmentisreinforcedbytheextremelyhighlosses(over50%)associated

    withthecurrentwaterdistributionnetworkandbytheincreasinglyhighcostofwatertransport

    toremotelocations.Ithasbeendeterminedthatforasmallcommunitywithapopulationof200

    peopleconsuming0.40m3/daypercapita,alocallysitedsolardesalinationunitwouldprovide

    wateratalowercostthanifithadtobetransportedfromgreaterthan16kmaway(Akashet.al,

    997).Itisourgoaltodesignadesalinationsystemwhichwillbeacosteffectivesolutiontowater1

    shortagesforaruralcommunity.

    Althoughthisdesignisnotcurrentlybeingcompletedforarealclient,theneedforthistypeof

    developmentinJordanisveryapparent.WehaveengagedincommunicationwithDr.Mark

    ZeitounofEastAngliaUniversityintheUKaftermeetinghimduringhisvisittoMacdonald

    Campusinthefallof2009.Hehasinformedusthatoneofhiscolleagueshasexpressedinterestto

    himinselectingaJordanianvillageforaprojectverysimilartooursandweareexcitedtomake

    contactwiththisindividualtoobtainmoresitespecificinformationnecessaryforcompletionof

    hedesign.Wearealsohopefulthatourdesignworkcouldcontributetotheimplementationof

    uchaprojectintherealworld.

    t

    s

    40

  • AKNOWLEDGEMENTSewouldliketoacknowledgethefollowingpeoplefortheirinvaluableguidanceduringtheW

    conceptualizationofthisdesignproject:

    Dr.VijayaRaghavan,DepartmentofBioresourceEngineering

    Dr.JanAdamowski,DepartmentofBioresourceEngineering

    dan

    ApurvaGollamudi,BraceCenterforWaterResourcesManagement

    r.MousaMohsen,DepartmentofMechanicalEngineering,HashemiteUniversity,Jor

    r.MarkZeitoun,SchoolofInternationalDevelopment,UniversityofEastAnglia,UK

    D

    D

    41

  • REFERENCESAbdallah,S.etal.Performanceofaphotovoltaicpoweredreverseosmosissystemunderlocalclimaticconditions.Desalination.(2005)183:95104

    estine.AbuJabal,MohdS.etal.ProvingtestforasolarpowereddesalinationsysteminGazaPalDesalination.(2001)137:16

    Afonso,MariaDinaetal.,BrackishgroundwatertreatmentbyreverseosmosisinJordan.Desalination.(2004)164:157171

    .Ahmed,M.etal.Integratedpower,waterandsaltgeneration:adiscussionpaper.Desalination(2001)134,1:3745

    ions.Akash,BilalA.ExperimentalstudyofthebasintypesolarstillunderlocalclimateconditEnergyConversionandManagement.(2000)41,9:883890

    Alghoul,M.A.etal.Reviewofbrackishwaterreverseosmosis(BWRO)systemdesigns.RenewableandSustainableEnergyReviews.(2009)13,9:26612667

    ElsevierAlSulaimi,J."ImpactofirrigationonbrackishgroundwaterlensesinnorthernKuwait."Agriculturewatermanagement31(1995):7590.CentreforAffordableWaterandSanitationTechnology,BiosandFilterManual:Design,Construction,&Installation,"(2007).Diawara,CourfiaK.'NanofiltrationProcessEfficiencyinWaterDesalination'.Separation&PurificationReviews.(2008)37,3:302324

    evelopmentDenny,Elaineetal.SustainableWaterStrategiesforJordan.InternationalEconomicDProgram,UniversityofMichigan,AnnArbor.(2008)Eltawil,MohamedA.etal.Areviewofrenewableenergytechnologiesintegratedwithdesalinationsystems.RenewableandSustainableEnergyReview.(2009)13:22452262

    Farid,Mohammed,etal.Solardesalinationwithahumidificationdehumidificationcycle.Desalination.(1996)106,13:427429

    Hasnain,SyedM.etal.CouplingofPVpoweredRObrackishwaterdesalinationplantwithsolarstills.Desalination.(1998)116:5764

    nunit

    42

    Hryashat,EyadS.Brackishwaterdesalinationbyastandalonereverseosmosisdesalinatiopoweredbyphotovoltaicsolarenergy.RenewableEnergy.(2008)33:17841790

    ryashat,EyadS.ViabilityofphotovoltaicsasanelectricitygenerationsourceforJordan.nternationalJournalofSustainableEngineering,(2008)2:1,6777.

    HI

  • 43

    Jaber,JamalO.etal.EvaluationofnonconventionalwaterresourcessupplyinJordan.Desalination,(2001)136:8392.Karameldin,Alyetal.TheRedSeaareawinddrivenmechanicalvaporcompressiondesalinationsystem.Desalination.(2002)153:4753ahmoud,MarwanM.'Solarelectricpoweredreverseosmosiswaterdesalinationsystemforthe

    03)Mruralvillage,AlMaleh:designandsimulation'.InternationalJournalofSustainableEnergy,(2023,1:5162.Mickley,R.Hamilton.Membraneconcentrationdisposal.AmericanWaterWorksAssociationResearchFoundation,Denver,Colorado.(1993).

    7)Mohsen,MousaS.WaterstrategiesandpotentialofdesalinationinJordan.Desalination,(200203:2746.Mohsen,MousaS.etal.Aphotovoltaicpoweredsystemforwaterdesalination.Desalination.(2001)138:129136

    )Nadav,N.BoronremovalfromthepermeateofalargeSWROplantinEilat.Desalination.(2005185,13:121129NationalDrinkingWaterClearinghouse,"SlowSandFiltration,"TechBriefFourteen,June2000

    006)Rijsberman,FrankR.WaterScarcity:Factorfiction?.AgriculturalWaterManagement.(280:522Veza,JoseM.etal.Electrodialysisdesalinationdesignedforwindenergy(ongridtests).esalination.(2001)141:5361D