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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
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EXECU IVESUMMARYT
TheKingdomofJordanisthe10thwaterpoorestcountryintheworldandthe4thwaterpoorest
countryintheMiddleEast.Thenaturalwaterresourcesofthecountryarenotsufficienttomeet
thedemandsofthepopulationandbecauseofthiswaterrationinghasbeeninplacesincethe
1980s.Currently,theeconomicallyviableharnessingofsurfacewaterhasbeenmaximized,
groundwaterisbeingpumpedat160%ofthesustainableyield,andnonrenewablefossilwateris
alsobeingutilized.Arapidlygrowingpopulationandindustrialsectorthreatentoexacerbatethe
watershortageintheverynearfuture.Jordanianscientistsinpartnershipwithinternational
organizationshavedeterminedthatdesalinationofsalinewaterwillplaythemostimportantrole
inalleviatingthecountryswaterscarcityproblems.Thisdocumentwilloutlineadesignproposal
foradesalinationunittobepoweredbyarenewableenergysourcethatwillprovidesufficient
reshwaterfortheneedsofasmallruralcommunityinJordan.f
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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
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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
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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.
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Fortunately,islandnationssufferingfromsaltwaterintrusiontypicallyhavehighwindresources.
Thearidandsemiaridregionsoftheworldarealsosomeofmostsolarresourcerichareas,which
makesense,becausethedriestareastendtohaveincreasedinsolarirradiationbecauseoftheir
proximitytotheequator.Undertheseconditions,thecouplingofarenewableenergysystem
(windpower,solarthermal,geothermal)tothedesalinationprocessmakeswatertreatment
easibleinremoteareas.(Eltawiletal.,2009).f
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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
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TheZarqaRiverwatersystemisbecomingincreasinglypollutedfromtheindustrialareaaround
theZarqaAmmanregion,where70%ofJordansindustryislocated,anditsabilitytoprovide
cleanwaterhasbeengreatlydiminished.SyriahasbuiltanumberofdamsontheYarmoukin
ordertodivertwaterforitsownpurposes.Perhapsanevengreaterstrainonthesurfacewater
resourcesforJordanhasbeentheconstructionoftheNationalWaterCarrierbyIsraelin1967,
whichtakeswaterfromupperJordanRiveratLakeTiberias.Theconstructionofthisprojecthas
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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
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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
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. 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
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3. LITERATUREREVIEW
3.1.DESALINATIONTECHNOLOGIES
Whenwetalkaboutdesalinationtechnology,wefirstneedtodefineitasaseparationofsaline
aterintotwomainstreams:w
thefreshwater(
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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
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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
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MechanicalVaporCompression(MVC)andThermalVaporCompression(TVC):
Vaporcompressionisanotherdistillationprocess.Aftersalinewaterisheatedbyanauxiliaryheat
elementintheboilingchamberthegeneratedvaporsarecompressed,therebyincreasingpressure
andtemperatureofthesteam.Thecompressedsteamisroutedbackthroughtheboilingchamber
viaaheatexchangeronwhichthesteamcondensesandreleasesthelatentheatbacktotheboiling
liquid,recyclingtheenergy.Thecondensationofthesteamresultsintheproductionofveryhot
distilledwater,whichpreheatsthesalinefeedwaterenteringthesystemwhilecoolingthefinal
productandincreasingenergyrecyclingwithinthesystem.Thissystemcanuseeithera
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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).
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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
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Figure2belowshowsallofthepotentialdesalinationtechnologycombinationsforgeothermal
energy.
SOLARGeographicallyspeaking,thereareoftenabundantsolarresourcesinregionswithaneedfor
desalinationinstallations.Thisisbecausearidregionswithfewwaterresourcestendtobecloser
otheequatorwhereincidentsolarradiationisthehighestonthesurfaceoftheEarth.t
Theoutputofsolarenergysystemstendstoberelativelyunpredictableandintermittentand
becauseofthiscondition,typicallyrequiresanenergystorageunitinordertoensurecontinuous
perationofsolarenergydrivenmachines.o
Solarenergytechnologycanbedividedintotwogeneralcategories:solarthermalandsolar
lectric.e
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Solarthermalreferstothecollectionofsolarenergyasheat.Lowandmediumtemperature
systemsareflatplatecollectorswithalargenumberoftubesencasedinatransparentplastic
enclosure.Thetransparentplasticcreatesagreenhouseeffectandthetrappedheatisthen
transferredtotheworkingfluidwhichhasahighheatcapacity.Hightemperaturesystemsuse
reflectorstoconcentratesolarenergyinordertogeneratewatervapourstopowerasteam
turbine.Whilethesesystemsarehighlyefficient,theapplicationofconcentratedsolarpowerfor
electricitygenerationissomewhatrestrictedtolargescaleinstallations.Thesesystemscanbe
usedasadirectsourceofthermalenergyfordistillationprocesses.Thermalenergycanbestored
inlargemassesofconcrete,ceramics,orothersuchmedia(Eltawiletal.,2009).
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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
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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
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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
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2CartridgeFilters
Asforthefilteringapplications,thechoiceofusingthecartridgefilterisacriticalonesinceitisa
sedimentfilter,thatistosayitreducetheamountofsedimentstransportedbythefluidtrough
filtration.Thechoiceofcartridgefilterwilldependontheapplication.Thecartridgefiltersare
preferableforsystemswithlowcontamination.Thecartridgefiltersasillustratedinfigure3are
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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
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.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
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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
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largevolumesofbrine,aswellasanadequatesourceof'fresher'water
cheap,flatland,oflowpermeability,andhighthermalandstructuralstability
pondarea(minimumsizeonehectareandmaximumoftenhectares)(Ahmedetal.,2001)
Onceagain,sincethismethodrequireslargevolumesofbrinedisposalwecannotimplementthis
techniqueforourdesignprojectsincewewillbedealingwithasmallscaledesalinationplant
whichproduceslowbrineeffluentanddisposesofarelativelysmalllandareafortheinstallation
fthebrinedisposalequipmentandtechnology.o
Figure5:Saltgradientnonconvectivesolarpond(Ahmedetal.,2001).
24
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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
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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
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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
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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
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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
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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.
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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
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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
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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
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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
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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
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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
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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
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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
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AKNOWLEDGEMENTSewouldliketoacknowledgethefollowingpeoplefortheirinvaluableguidanceduringtheW
conceptualizationofthisdesignproject:
Dr.VijayaRaghavan,DepartmentofBioresourceEngineering
Dr.JanAdamowski,DepartmentofBioresourceEngineering
dan
ApurvaGollamudi,BraceCenterforWaterResourcesManagement
r.MousaMohsen,DepartmentofMechanicalEngineering,HashemiteUniversity,Jor
r.MarkZeitoun,SchoolofInternationalDevelopment,UniversityofEastAnglia,UK
D
D
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