DESALINATION TECHNOLOGIES
DesignandOperation
IQBALM.MUJTABA
DepartmentofChemicalEngineering, UniversityofBradford,Bradford,UnitedKingdom
MDTANVIRSOWGATH
DepartmentofChemicalEngineering, BangladeshUniversityofEngineeringandTechnology, Dhaka,Bangladesh
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Authors
IqbalM.Mujtaba isaProfessorofComputationalProcessEngineering andiscurrentlyAssociateDean(Learning,TeachingandQuality)ofthe FacultyofEngineeringandInformaticsattheUniversityofBradford.He wastheHeadoftheSchoolofEngineeringattheUniversityofBradford from2016to2018.HeobtainedhisBScEngandMScEngdegreesin ChemicalEngineeringfromBangladeshUniversityofEngineeringand Technology(BUET)in1983and1984,respectively,andobtainedhisPhD fromImperialCollegeLondonin1989.HeisaFellowoftheIChemE,a CharteredChemicalEngineer.HewastheChairoftheEuropeanCommitteeforComputersinChemicalEngineeringEducationfrom2010to 2013andtheChairoftheIChemE’sComputerAidedProcessEngineering SpecialInterestGroupfrom2012to2019.HeiscurrentlyanAssociate Editorfor AsiaPacificJournalofChemicalEngineering,SouthAfricanJournalin ChemicalEngineering,ChemicalProductandProcessModelling andanEditorial BoardMemberof Desalination.
ProfessorMujtabaleadsresearchintodynamicmodeling,simulation, optimization,andcontrolofbatchandcontinuouschemicalprocesseswith specificinterestsindistillation,industrialreactors,refineryprocesses,desalination,wastewatertreatment,andcrudeoilhydrotreatingfocusingon energyandwater.Hehasmanagedseveralresearchcollaborationsand consultancyprojectswithindustryandacademicinstitutionsintheUnited Kingdom,Italy,Hungary,Malaysia,Thailand,India,Qatar,SouthAfrica, Iraq,Jordan,Algeria,China,Libya,Bahrain,andSaudiArabia.Hehas publishedmorethan380technicalpapersandhasdeliveredmorethan75 invitedlectures/seminars/plenaries/keynotes/shortcoursesaroundthe world.Hehassupervised37PhDstudentstocompletionandiscurrently supervising10PhDstudents.Heistheauthor/coauthorof(1) Batch Distillation:DesignandOperation (textbook)publishedbytheImperial CollegePress,London,2004,(2) “WastewatertreatmentbyReverse Osmosis” publishedbyCRCPress,2020.Heisoneoftheco-editorsofthe books(1) ApplicationofNeuralNetworksandOtherLearningTechnologiesin ProcessEngineering,ImperialCollegePress,London,2001,(2) Composite MaterialsTechnology:NeuralNetworkApplications,CRCPress,2009,(3) The Water-Food-EnergyNexus,CRCPress,2017,(4) WaterManagement:Social andTechnologicalPerspective,CRCPress,2018.
Dr.MdTanvirSowgath isanAssociateProfessorofChemical EngineeringDepartment,BangladeshUniversityofEngineeringand Technology(BUET),Bangladesh,andiscurrentlytheVisitingAcademicof theSchoolofEngineering,UniversityofBradford,UK.HeisanAssociate MemberoftheIChemE(UK)andisaBUETtechnicalrepresentativefor theBangladeshEnergyRegulatoryCommission(2021).Hewasselectedas technicalcommitteememberfortheBangladeshMinistryofEnvironment (2010,2014),technicalcommitteememberofSylhetGasFieldforthe BangladeshMinistryofEnergyandMineralResource(2014 2015), DepartmentofPublicHealth(2013)andBangladeshEnergyRegulatory Commission(2021).Hehas12yearsofteachingandresearchexperiencein the fieldofChemicalEngineeringasanAssistantProfessorandAssociate ProfessoratBUET.Hehasofferedanumberofcoursesinrecentyearsin (a)UnitoperationofChemicalProcess,(b)FundamentalsofEnvironmentalEngineering,(c)IndustrialPollutionControl,(d)AirPollution Control,(e)OptimizationofChemicalProcess,and(f)ComputerAided ProcessDesign.
Dr.SowgathstudiedhisBScEngineeringdegreeinChemicalEngineeringatBUETandobtainedhisPhDdegreefromtheUniversityof Bradfordin2007.HisPhDdissertationwasentitled “NeuralNetwork basedhybridmodellingandMINLPbasedoptimizationofMSFdesalinationprocesswithingPROMS.” Dr.Sowgathsetthestoneforgraduate levelresearchindesalinationattheUniversityofBradfordwhichhasbeen carriedforwardbyseveralresearchersatBradfordafterhim.
Dr.Sowgath’smainresearchinterestsareinprocessmodeling,dynamic simulation,steadystate,anddynamicoptimizationofchemicalprocesses withspecificinterestsinDesalination,GasProcessing,andRefinery.Hehas supervisedseveralundergraduateandMScprojectsatBUETandhas publishedseveraltechnicalpapersinjournalsandconferenceproceedingsin theareaofDesalination,GasProcessing,Refinery,andFertilizerProcessing.Hiscurrentresearchfocusindesalinationisonfaultdiagnosis,scheduling,andmaintenance.
Preface
Afterair,waterisoneofthemostvitalelementsresponsibleforlifeonthe earth.Throughouthistory,ithasdeterminednotonlywherepeoplelive butalsotheirqualityoflife.Qualitywaterisoneofthekeyfactorsof qualitylife.Thefoodweeat,thehousewelivein,thetransportsweuse, andthethingswecannotdowithoutin24/7/365determineourqualityof lifeandrequiresustainableandsteadywatersupplies.By2030,theglobal waterneedwouldbe6900billionm3/daycomparedto4500billionm3/ dayrequiredin2009.Elevenpercent(11%)oftheworldpopulationdonot havecleanwaterclosetohome.Globally,watercontaminatedwithfecesis themaindrinkingwatersourceforabout2billionpeople.Atpresent,the requirementforfreshwaterisgrowingby64billioncubicmetersayear, whiletheworld’spopulationisrisingbyroughly80millionpeopleeach year.Thegrowingpopulationdemandsincreasingproductionoffoodand thusrequiresanincreasingamountofirrigationwater.Note,over70%of thewaterconsumptionisduetoagriculturaluse.Thesharpincreaseinthe productionofbiofuelsinrecentyearsalsohasasignificantimpactonwater demand.Productionofasingleliterofbiofuelneedsbetween1000and 4000litersofwater.
Asthepopulationcontinuestoriseandisanticipatedtoreachover9 billionby2050,thedemandforfreshwaterwillcontinuetoincrease. Exponentialgrowthinpopulationandimprovedstandardsoflivingrequire increasingamountoffreshwaterandareputtingseriousstrainonthe quantityofnaturallyavailablefreshwateraroundus.Also,thedisproportionaldistributionofwealtharoundtheworldhasaparttoplayinthe demandforwaterasthewasteandexcesswatersupplyofwealthynationsis causingpoverty-strickenregionstosuffer.Ontheotherhand,waterhas beenadeviceusedforreligiousconflictandregionalandlocalbattles, leadingtowavesofmigrationtoothercountries.Globalthirstwillturn millionintowaterrefugees.Thewaterdisputeswillinevitablybecome morecommon,as220riverbasinsgloballyaresharedbytwoormore countries.Extremewatershortagesescalatedsectarianviolenceinmany countries.
Although71%oftheearth’ssurfaceiscoveredbywater,theAncient Mariners’ rime: “Water,watereverywhere/Notanydroptodrink” isin linewith97%oftheplanet’swaterbeingeithersaltyorundrinkable.Ofthe
remaining3%,over2.5%isfrozenandfoundinAntarctica,theArctic,and glaciersandisnoteasilyaccessibleforhumanuse.Thus,theonlyavailable waterforhumanitytouseisaround0.5%oftheEarth’swater,whichis foundinlakes,rivers,andaquifers.Withmostoftheaccessiblewater aroundusbeingsaline,desalinationtechnologyisvitalforoursustainability. Desalinationmarketsgrewsignificantlyinthelastdecades.Asiaisbecoming afast-growingmarketduetoitsenormouspopulationandeconomic growth,leadingtoawaterdemandthatcannotbefulfilledwithconventionalwatersources.Thecommonlyusedindustrialdesalinationprocesses canbeclassifiedbroadlyintotwogroups:(a)thermalprocessesand (b)membraneprocesses.
Numerousstudieshavebeencarriedoutinthepastdecadestodevelop moresustainabletechnologicalsolutionsthatwouldmeettheincreasing waterdemand.Theongoingobjectiveisstillbeingtheimprovementin design,operation,andcontrolofdesalinationprocessestoensurequality water(intermsofsalinityandotherdissolvedsolidssuchasboron)atamore economicalpricewithalowerenvironmentalimpact.
Theearliertextbook FundamentalsofSaltWaterDesalination publishedin 2002byElsevieroutlinesthefundamentalconceptsinthermalandmembranedesalinationwithsimpleprocesscalculations.Theworldhas considerablymovedsincethenintheresearchandapplicationofdesalinationtechnologiesformakingfreshwater.Itistherighttimethatanew bookiswrittenhighlightingrecentdevelopmentsindesalination.This bookhighlightsthestateoftheartinmodel-basedtechniquesusedin evaluatingvariousdesalinationprocesses(intermsofdesign,operation, control)inadditiontohighlightingexperimentalresearchpublishedinthe lastdecades.Forboththermalandmembranedesalinationprocesses,several modelsfromsimpletodetailedhigh fidelityarepresentedwithcasestudies. Severaloptimizationproblemswithsingle-tomultiobjectivefunctions (productivity,profit,energyconsumption,performanceratio)arehighlightedandexplainedwithexamples.
Hybriddesalinationsystemscombiningboththermalandmembrane processeswithpowergenerationsystemsareconsideredbetter(intermsof economics,energyconsumption,andoperational flexibility)thandualpurpose(powerandwater)evaporationplants.Thisbookhighlightsthe recentdevelopmentsinhybriddesalinationprocesses.
Thefutureglobalenergycrisishasledseveralcountriestosetupplansto diversifytheirenergyresources.Alternativedesalinationprocessesrelying onrenewableenergysources(RESs)suchassolar,wind,andgeothermal
Preface xvii
energyarebeinginvestigatedtodesalinateseawateranddevelopinnovative energy-efficientdesalinationtechnologieswithsignificantlylessenvironmentalaffectintermsofgreenhousegasemissionsandcarbonfootprint. Variousmethods(experimentaltosimplecalculations)toevaluatethe economicviabilityofcouplingRESwithdesalinationplantshavebeen broughttothepublicdomaininrecentyears.Thisbookalsohighlightsthe useofvariousrenewableenergiesindesalination.
ApplicationofArtificialIntelligence(AI)includingArtificialNeural Network(ANN)techniques,inallaspectsofprocessengineering(including desalination)activities,frommodeling,optimization,parameterestimation, faultdiagnosis,errordetection,datareconciliationtocontrol,hasreceived considerableattentioninrecentyears.NNtechniqueshaveshowngreat promiseovertherecentyearstosolveproblemsthathaveproventobe difficultforthestandardtechniqueusingdigitalcomputers.Theapplication ofNNinthecontextofdesalinationisalsohighlightedinthisbook.
Thisbookconsistsof14Chaptersandmorethan50%ofthisbookwill includeourownresearchindesalinationprocesses(boththermaland membrane)since2003.Severalcasestudiesondesign,operation,control, faultdetection,anddiagnosisarepresentedtogiveaclearandbetter understandingofdifferentdesalinationprocesses.Thebookwillnotonlybe usefulforundergraduateteachingbutalsoforpostgraduateresearchand industrialpractitionersindesalinationfortheyearstocome.
ProfessorIqbalMMujtaba UniversityofBradford,UK
Professor(Associate)MdTanvirSowgath BangladeshUniversityofEngineering&Technology,Bangladesh
CHAPTER1 Introduction
Demandon finiteresourcesisincreasing,andtheglobalpopulationis expectedtoexceed9billionby2050.AccordingtotheInstitutionof ChemicalEngineers(IChemE,UK),thefourkeychallengeareasthesocietywillconfrontinthecomingdecadesare(https://www.icheme.org/ knowledge/policy/chemical-engineering-matters/):
• Water
• Energy
• Foodandnutrition
• Healthandwell-being
1.1Worldwaterdemandandcrisis
Waterisoneofthemostvitalelementsresponsibleforlifeontheearth. Throughouthistory,notonlyhasitdeterminedwherepeoplelivebutalso theirqualityoflife(Rosenbaum,2009).Asthepopulationcontinuesto growandisexpectedtoreachover9billionby2050(GEReportsStaff, 2017),thedemandforcleanwaterwillcontinuetoincrease.Exponential growthinpopulationandimprovedstandardsoflivingrequireincreasing amountoffreshwaterandareputtingseriousstrainonthequantityof naturallyavailablefreshwateraroundus.TheAncientMariners’ rime: “Water,watereverywhere/Notanydroptodrink” isinlinewith97%of theplanet’swaterbeingeithersaltyorundrinkable.Oftheremaining3%, over2.5%isfrozenandfoundinAntarctica,theArctic,andglaciersandis noteasilyaccessibleforhumanuse.Thustheonlyavailablewaterforhumanitytouseisaround0.5%oftheEarth’swater,whichisfoundinlakes, rivers,andaquifers(Fig.1.1).
Fig.1.2 showsthedemandofwaterindifferentregionsoftheworld.By theyear2030,theglobalneedsofwaterwouldbe6900billionm3/day comparedto4500billionm3/dayrequiredin2009(2030WaterResources Group,2009).Currentlythedemandforfreshwaterisincreasingby64 billioncubicmetersayearwhiletheworld’spopulationisgrowingby roughly80millionpeopleeachyear.Thegrowingpopulationdemands
DesalinationTechnologies
ISBN978-0-12-813790-1
https://doi.org/10.1016/B978-0-12-813790-1.00015-3
Figure1.1 Distributionofglobalwater. (Adaptedfrom https://www.sciencelearn.org.nz/resources/723-water-origins ,accessedonApril30, 2021.)
Figure1.2 Globalwaterconsumption(billionsm3 peryear)byregion. (Adaptedfrom http://12.000.scripts.mit.edu/mission2017/social-solutions-to-energy-and-water-problems/ (accessedonApril30,2021).)
increasingproductionoffoodandthusrequiresincreasingamountof irrigationwater(ElimelechandPhilip,2011; EuropeanEnvironment Agency,2012).Over70%ofthewaterconsumptionisduetoagricultural use(Fig.1.3).Note,thesharpincreaseintheproductionofbiofuelsin recentyearshasalsosignificantimpactonthewaterdemand.Between1000
Figure1.3 Wateruseintheworld. (https://blogs.worldbank.org/opendata/chartglobally-70-freshwater-used-agriculture ,accessedonApril30,2021,andadapted.)
and4000Lofwaterareneededtoproduceasingleliterofbiofuel(http:// www.worldometers.info/water/ accessedonJuly19,2018). Table1.1 showsthewaterconsumptionforproducingdifferenttypesoffoods.Increaseinwaterdemand(forallpurposes)increasesthedemandofenergy (Mujtabaetal.,2017)duetothefactthatcurrentlymostofthedesalting technologiesrequiressignificantamountofenergy.Atpresent,morethan 20%oftheworld’spopulationliveinareasofphysicalscarcity(Fig.1.4). Moreover,aroundonequarteroftheworld’spopulationfaceeconomic watershortagewheretheircountrieslacktheappropriateinfrastructureto takewaterfromthesource(UN,2007).
Thedisproportionaldistributionofwealtharoundtheworldhasapart toplayonthedemandforwater,asthewasteandexcesswatersupplyof wealthynationsiscausingpoverty-strickenregionstosuffer.Ontheother hand,waterhasbeenadeviceusedforreligiousconflictandregionaland localbattlesleadingtowavesofmigrationtoothercountries(U.S.National AcademyofSciences,1999; Kreamer,2012; Mujtabaetal.,2018).Global thirstwillturnmillionintowaterrefugees.Thedisputesoverwaterwill inevitablybecomemorecommon,as220riverbasinsgloballyaresharedby twoormorecountries(TheIndependent,2001).Asthepricesofimported
Table1.1 Waterconsumptionforproducingdifferenttypesoffoods. FoodstuffQuantityWaterconsumption,liters
Chocolate1kg17,196
Beef1kg15,415
Sheepmeat1kg10,412
Butter1kg5,553
Chickenmeat1kg4,325
Cheese1kg3,178
Rice1kg2,497
Cotton1@250g2,495
Pasta(dry)1kg1,849
Bread1kg1,608
Pizza1unit1,239
Apple1kg822
Potatoes1kg287
Milk1 250mLglass255
Cabbage1kg237 Egg1196
IMechE,adaptedfrom https://www.theguardian.com/news/datablog/2013/jan/10/how-much-waterfood-production-waste#data accessedonSeptember25,2018.
Figure1.4 Areasofphysicalandeconomicwaterscarcity. (Adaptedfrom http://ses. wsu.edu/wp-content/uploads/2017/10/water.pdf ,GlobalWaterInitiative,GEFInternationalWaterConference,accessedonApril30,2021.)
watergoup,manycountries(e.g.,Singapore)dependentonthepotable watersupplyfromothercountries(e.g.,Malaysia)turnedtonewtechnologytomakepotablewaterfromreclaimedwater.Scarcityofwatercan leadtoriots(Fig.1.5).Withoutmoreeffectivewatermanagementsystems,
Figure1.5 WaterwarinIndia(2009).May25,2009. (Adaptedfrom http://www. treehugger.com/clean-water/violence-over-water-already-happening-in-india.html (accessedonDecember30,2018).)
lackofwateravailabilitywillbecomeaproblemthreateningnationalsecurityinmanycountriesimportanttotheUnitedStates(Busby,2017). ExtremewatershortagesescalatedthesectarianviolenceinYemenand playedaveryimportantroleintheinstigationandthecontinuationofthe civilwar.Thelinkbetweentheenvironmentalproblemsandconflictis alreadywellestablishedandgiventheextremewatershortages,theMiddle Eastisparticularlyvulnerabletoenvironmentallyinducedinstabilities (Shahi,2016; ShahiandVachkova,2018).
Interestingly,arecentUNreportestimatedthatthreeoutoffourjobs thatmakeuptheglobalworkforceareeitherheavilyormoderately dependentonwater.Thismeansthatwatershortagesandproblemsof accesstowaterandsanitationcouldlimiteconomicgrowthandjobcreationinthecomingdecades.Thereportalsohighlightsthatwaterandjobs areinextricablylinkedtoeconomic,environmental,orsocialperspective. Thisreportbreaksnewgroundbyaddressingthepervasiverelationship betweenwaterandjobstoanextentnotyetseeninanyotherreport (https://en.unesco.org/news/water-drives-job-creation-and-economicgrowth-says-new-report,accessedonDecember30,2018).
1.2Wastewater,reclamationandreuse,social perception
Astheworldpopulationgrows,theheavilyindustrializedworldweliveor strivetolivecontinuestogeneratevastamountofwastewaterplaguedwith industrialeffluents,sewage,andmanyharmful,somecarcinogenic,byproducts,whichareoftensimplydisposedofinriversandoceans.An estimatedminimumlethaldoseofphenolis140mg/(kgofbodyweight)in humans(Binghametal.,2001).TheEuropeanFoodStandardsAgency (EFSA)established0.5mg/(kgofbodyweight)/dayforphenol(EFSA, 2013).Globally,morethan2billionpeopledrinkcontaminatedwater whichtransmitsdiseasessuchasdiarrhea,cholera,dysentery,typhoid,and polioandcauseoverhalfamilliondiarrhealdeatheachyear(http://www. who.int/news-room/fact-sheets/detail/drinking-water,accessedonJuly 20,2018).Theyuckfactor,thetermssuchas recycledsewage and toilet-to-tap usedbymediaincharacterizingreclaimedwater,givessignificantnegative imagestoaugmentreclaimedwastewaterreuse,especiallyfordrinkingand agriculturalproductionpurposes(Miller,2006; Chenetal.,2015).Even thoughinthecountrylikeIndia,UrineTherapywaspromotedin1978by thePrimeMinisterofIndiaMr.Desai(https://en.wikipedia.org/wiki/
Urine_therapy,accessedonDecember30,2018),theyuckfactorisstill dominatinginmanypartsoftheworldwhenitcomestotheuseoftreated wastewater(Ravishankaretal.,2018)(Fig.1.6).AccordingtoCNNnews (March19,2019)severewatershortagescouldplungeEnglandinto ‘jawsof death’ in25yearsandaccordingtoBBCnews(May10,2013)London ‘coulddrinktreatedsewage’ (Fig.1.7). Table1.2 showstheuseoftreated andnontreatedwastewaterindifferentcountries.
1.3Sustainablewatersupplyandmanagement
Exponentialgrowthinpopulationandthefundamentalrighttohavebasic foodandstandardsoflivingrequireincreasingamountsofwaterandenergy.Thequantityofavailablefreshwaterandenergysourcesthatdirectly affectthecostofproduction(irrigationandenergy)andthetransportation (energy)offoodarediminishing.Inaddition,thereisincreasedwater pollutionduetoindustrialusesofwater.Thedirectuseofsuchwaterfor humanconsumptionaswellasirrigationforfoodproductionisprohibitive andrequirestechnologicalsolutions.Asnotedearlier,currently70%ofthe totalwaterconsumptionisforagriculturalpurpose.Securingsustainable water,food,andenergysuppliesaremoreimportantchallengestodayfor scientistsandengineersthaneverbefore.Therefore,tostartmanagingthese resourcescarefullyisnotonlyalocalizedproblembutglobalizedtoo.The managementofwaterincludes(a)cost-effectiveandsustainableproduction offreshwaterviawatertreatmentofriverorreservoirwaterorvia
Figure1.6 Factorsinfluencingtherespondents’ decisiontonotbuyreclaimed water. (Adaptedfrom Ravishankaretal.(2018).)
Figure1.7 PredictedwatershortageanduseoftreatedwaterinLondon. (CNNand BBCnews.)
Table1.2 Purposesandratesofusingwastewaterinsomecountries.
CountryPurposeRateNotes
PakistanAgricultural96%Nontreatedwastewater
TunisiaAgricultural86%Treatedwastewater
SingaporeMunicipal45%
NamibiaMunicipal29%NamibiaandSingaporehavethemost importantwaterreuseforhuman consumptionreclamationprojects
Industrial51%
GermanyIndustrial69%
USIndustrial45%TheUnitedStatesandGermanyhavea largernumberofrecyclingandreuse projectsacrossvariousindustries
Adaptedfrom JiménezandAsano(2008)
desalinationofseawater,(b)wastewatertreatmentandreuse,(c)efficient andcost-effectivewaternetworkfordistribution,(d)effectiveuseofwater inagricultureandindustries,and(e)waterdemandmanagement.
Althoughthisbookisdedicatedonthetechnicalaspectsoffreshwater productionbydesalination,someoftheaboveaspectsofwater
managementwillbebrieflyreferredhere(detailscanbefoundin Mujtaba etal.(2017, 2018)).
1.3.1Wastewatertreatmentandreuse
Inthelast50years,asharpincreaseinthevolumeofindustrialeffluents (andsewage)beinggeneratedanddisposedofintoriversandoceansis witnessedcausingsignificantharmonourecosystem.Withthecontinued populationriseamarkedshortagefordrinkingwaterisalsonoticed. Becauseofthesecompetingaspects,thereisaneverincreasingandurgent needfor findingbetter,faster,andcheapermethodsfortransforming wastewaterintodrinkablewateroratleastcleanerwaterthatcanbeusedin variousapplicationssuchasdomestic,agriculture,andindustry. Mujtaba etal.(2018) notedseveralwastewatertreatmentprocesses.
Amosaetal.(2018) focusedonmodel-basedevaluationofporeblockingbehaviorsoflowpressuremembranesforwastewatertreatment. MathabaandDaramola(2018) discussedSodalite-andChitosan-based compositemembranematerialsformetalremovalfromthewastewater. Al-Obaidietal.(2018a) highlightedROprocessfortheremovalof phenoliccompoundsfromwastewaterusingmodel-basedtechniques. AlObaidietal.(2018b) consideredsimultaneousremovalofeightselected organicandinorganiccompoundsfromwastewaterusingROprocess.The contaminantswere:dimethylphenol,chlorophenol,phenol,methylorange dye,aniline,ammonium,cyanide,andsulfate.
Jarullahetal.(2018) introducedindustrialthreephaseoxidationreactor forwastewatertreatment,while Dahroug(2018) consideredelectrolytic treatmentofwastewaterforreusepurpose.Inactivationofwaterborne pathogensinmunicipalwaterusingozonewasdescribedby Mechaetal. (2018). Zachariaetal.(2018) providedanoverviewofGTL(Gas-toLiquid)processwaterproductionandthepotentialofphotocatalyticwater treatmentinremovingnonoxygenatedhydrocarbons(anorganiccontaminantmostpredominantlyfoundintheGTLprocesswater).
Adsorptionisawidelyusedtechniquefortheremovalofpollutantsasit isasimpleandrelativelyeconomicmethod.Adsorptionisaprocessthat takesplacewhenagasorliquidsoluteaccumulatesonthesurfaceofasolid oraliquid(adsorbent),formingamolecularoratomic film(theadsorbate). Man-madedyesareextensivelyusedinmanyindustriessuchaspaper, pharmaceutical,cosmetics,paint,leather,food,andtextileindustries.The azodyesareamongthebiggestclassofdyes,correspondingtomorethan 60%ofmanufacturedsyntheticdyes.Amongtheazodyes,methyleneblue
(MB)isthemostcommonlyuseddyeinpapercoloringandintextile industriesitisthemaincontributorsofgeneratingwastewatergenerators. Hassanetal.(2018) consideredbiosorptionofmethylenebluedyefrom wastewaterusingAnisetearesidue.Adsorptionisalsooneofthemore effectivemethodsforremovingheavymetalsfromindustrialwastewaters. El-tahhan(2018) studiedtheeffectivenessofusingactivatedcharcoaland treatedricehusk(TRH)toremoveChromiumionfromsynthetic wastewatersusingbatchand fixedbedcolumnadsorptiontechniques. Waterpollutionbyammonianitrogen(NH3 N)isduetoagricultural runoff,releasingofuntreatedlandfillleachateandsewage,urbanactivities, etc.Over-enrichmentofammonianitrogencauseseutrophication,depletionofdissolvedoxygenandbringstoxicitytoaquaticorganisms.Among severalmethods,adsorptionmethodhasagainbeenfoundtobethemost convenientandeconomicalmethodtoremovesuchpollutantfrom wastewater(Zahrimetal.,2018).
Anaerobicdigestion(AD)isabiologicalprocessforthetreatmentof wastewaterwithhighorganiccontentandisamongthewidelyapplied first steptreatmenttechnologiesinreducingthepollutionoftheseeffluents. However, Apolloetal.(2018) focusedonintegratingphotocatalytic degradationtreatmenttechniquewithADfortreatingwastewater contaminatedwithmethyleneblue.Theyusedphotodegradationasthe first steppretreatmentforimprovedsubstratebiodegradabilityfollowedbyAD asthesecondstep.Inbothprocesses,naturalzeolitewasemployedasa biomassandcatalystsupport.Petrochemicalindustryconsumesalotof waterandconsequentlyhugeamountsofmonoethyleneglycol(MEG) containingwastewaters(characterizedwithachemicaloxygendemand (COD)rangingfrom500to30,000mg/L)aregeneratedwhichaffect negativelyontheenvironment,health,andundoubtedlycontaminatethe waterstreams.Thechallengeoftreatingpetrochemicalwastewatereffluents willremainachallengeforthenextfewdecadesandtheapplicationofAD processforenergyproductionintermsofethanol,hydrogen,andmethane frompetrochemicalwastewaterisapromisingtechnology. Tawfikand Elreedy(2018) consideredsimultaneoustreatmentandbioenergyproductionfrompetrochemicalwastewatercontainingMEGandphenol.Mostof agro-industrialeffluentcontainshugeamountsoffatsandoils(Tawfikand Elsamadony,2018).Thelipidscontentintheend-of-pipeeffluentmainly dependsontherawmaterialsandtypeofindustry,i.e.,woolscouringand olivemillgeneratesevereeffluentswithlipidsconcentrations(5 25g/L), sunfloweroilmillwastewater(0.2 1.3g/L),dairywastewater(0.9 2.0g/L),
andslaughterhouseseffluents(0.35 0.52g/L). TawfikandElsamadony (2018) consideredADfortreatinglipid-richwastewater.Combinationof adsorptionandtheanaerobicdigestionoflipid-richwastewaterwasalso recommendedbytheauthorsasanexcellentapproachtomitigatethelongchainfattyacids(LCFAs)toxicity.
Mathematicalmodelsarepowerfultoolsthatthedesignersofbiological wastewatertreatmentsystemscanusetoinvestigatetheperformanceof potentialsystemsunderavarietyofconditions(Mustafaetal.,2018).They areparticularlyusefulforthosewhoareworkingwithsystemsinwhich carbonoxidation,nitrification,anddenitrificationareaccomplishedwitha single-sludgesystem.Duetocomplexandcompetingandparallelreactions insuchsystemsitisdifficulttointuitivelyestimatetheirresponsetochanges insystemconfigurationorload.
1.3.2Waternetworkfordistribution
Wastewatertreatmentprocessesareoftenseenasbolt-onorend-of-pipe operationinprocessindustries.Inreality,the firstpriorityshouldbeto ensurethatthewastewatergeneratedisminimizedbeforefocusingon wastewatertreatmentsystemsasanyreductioninwastewaterwillresultin reductioninbotheffluenttreatmentandfreshwatercosts(WangandSmith, 1994).Inpetroleumrefinery,wastewaterisgeneratedbytheprocesses whenwateriscontactedwithprocessmaterialsindesalting,streamstripping,andmanywashingoperationsthroughouttherefinery.Also,wastewaterisgeneratedbytheutilitysystemfromboilerfeedwatertreatment processes,boilerblowdown,coolingtowerblowdown,etc.Iffundamental changestoprocessesarenotconsideredtoreducetheirinherentdemandfor water,thentherearefewpossibilitiesforreducingwastewater(Wangand Smith,1994)suchas:
(i) Re-use. Wastewaterbeingreuseddirectlyinotheroperationsprovided thelevelofcontaminationdoesnotinterferewiththeprocess.Reuse mightrequirewastewaterbeingblendedwithwastewaterfromother operationsand/orfreshwater(Mananetal.,2006).
(ii) Regenerationandre-use. Wastewatercanberegeneratedbypartialtreatmenttoremovethecontaminantsandthenreusedinotheroperations. Again,reuseafterregenerationmightrequireblendingwithwastewater fromotheroperationsand/orfreshwater. Nyamayedenga(2018) consideredregenerationandreuseofindustrialwastewatertominimize overallfreshwaterusage.
Waternetworksynthesisanddesigntasksaddresstheminimizationof freshwaterdemandofaparticularprocesssystematicallywhichinvolve:(1) watertargetingand(2)networkdesign.Thewatertargetingstagedeterminestheminimumfreshwaterandwastewater flowsforanetwork, basedonspecifiedconcentrationand flowratelimits.Networkdesign wouldtheninvolvethedevelopmentofadetailedallocationstrategy amongtheindividualwater-consuming(Sink)andwater-producingprocesses(Source)(Alnourietal.,2017).
Mananetal.(2006) usedthewatercascadeanalysis(WCA)technique, basedonthepinchanalysisconcept,tominimizethewatertargetsforthe SultanIsmailMosqueattheUniversitiTeknologiMalaysia.TheWCA providedanumericalalternativetothegraphicalwatertargetingtechnique knownasawatersurplusdiagramwhichpredictedsavingsof65.1%fresh waterand51.5%wastewaterwithreuseonly,andupto85.5%freshwater and67.7%wastewaterwithreuseandregeneration. Tanetal.(2007) highlightedanewapproachfortheretrofitofwaternetworkwith regenerationwhichenabledfurtherreductionoftheutilitytargetstobe achievedinanexistingwaternetworkviawaterreuse,recycling,and regeneration. NyamayedengaandMujtaba(2014) appliedWCAtechnique tominimizeoverallfreshwaterusageinKarimbaWineryinZimbabwe whichrealized27%and68.8%reductioninfreshwater flowandwastewater generation,respectively.
Buabeng-Baidooetal.(2018) investigatedthewaterreuse/recycle opportunitiesinalarge-scalemilkprocessingplant(AmulDiary)inIndia usingprocessintegrationtechnique.Thecomplexdiarysystemswith multiplecontaminants(Fig.1.8)resultsinsuperstructureoptimization integratingthewaternetwork(WN)modelwiththeregenerationmodel. Note,theIndiandairysectoristhelargestintheworldandconsumes around62billionm3/yroffreshwater.Thestudyreportedasignificant reductioninthetotalcostofthenetwork,duetothesignificantreduction infreshwaterconsumption(byover20%)andwastewatergeneration(by over53%).
Industriesashighlightedaboveoften findsignificantchallengestohave sustainablestand-alonewatersuppliescompoundedwithanywastewater disposalobligationsresultinginheavyeconomicandenvironmentalpenalty.Whentherearewater-usingandwater-consumingsystemswithin geographicproximity(Fig.1.9),thispenaltycanbereducedbyhaving sharedwaterschemesbetweencoexistingclusterofindustries/plantsoften knownasanEcoIndustrialPark(EIP).ResourcescanbesharedinEIPsby
Figure1.8 Watertargetingandnetworkdesignforamuldairy. (Adaptedfrom Buabeng-Baidooetal.(2018).)
Figure1.9 Ecoindustrialparkwithsharedwaterresources. (Adaptedfrom Alnourietal. (2017).)
fosteringplant-to-plantinteractions.EffectivewatermanagementinEIPs heavilydependsontheimplementationofwaternetworkdesignschemes incorporatingwastewaterreuseandregeneration(Alnourietal.,2017; Fadziletal.,2018).
1.3.3Effectiveuseofwaterinagriculture
Asmentionedearlieronaverageover70%ofwaterconsumptionisdueto agriculturaluseintheworld(Fig.1.3),irrigationbeingthelargestconsumer ofwatertotalingover85%ofthetotalavailablewaterinthedeveloping countries(Aminetal.,2011).Andasignificantamountofwatergoesinthe productionofriceasitisthemostcommonfoodforoverhalftheworld population.Therefore,itisessentialtoimprovewaterproductivityaswell aswateruseefficiency.Note,asmallimprovementofwateruseinrice productionwillleadtosignificantsavingsinwater.As25%oftheworld’ s populationwheretheircountrieslacktheappropriateinfrastructuretotake waterfromsource(UN,2007),thesocioeconomicconditionandwater scarcity(Fig.1.4)insignificantpartoftheworldmustbringarevolutionin
irrigationrequiringmeasurestochangewaterdemandsandincreaseefficiencyinwateruse. PrecisionAgriculture isgettingthemomentuminthis respect(Milellaetal.,2019).
Environmentalsustainabilityisanabsolutelyessentialcomponent requiredforprecisionfarmingorsite-specificmanagementwhichrequires quicksoilspatialvariabilitydescription(relatingtopropertiessuchassalt concentration,texture,potentialtoholdplantnutrients)fordecisionmakingontherightinputattherightplace,attherighttimeandinthe rightamountorsite-specificzonemanagement(Aminetal.,2011).
ThemodernGIStechniqueisplayingasignificantroleinmanaging waterinagriculturallands.Itcancollect,store,andprocessinformationon wateruseforcropsresultinginreliableandvalidatedproceduresfor decision-making(planningofwaterallocationpolicyinirrigationsystem)as currentlyitisthemostefficienttoolforspatialdatamanagementandutilizationallowinggreaterunderstandingofthespatialvariance(Aminetal., 2011).
1.3.4Waterdemandmanagement
Ashighlightedearlier,theavailabilityoffreshwaterforoursurvivalisa criticalglobalchallengeandcertainlybeimpactedbytheclimatechange. RussellandFielding(2010) emphasizedthatwaterdemandmanagementis veryimportantinreducingthevulnerabilityoffreshwatersuppliesdueto climatechange.Certainly,the fieldofpsychologytogetherwithenvironmentalpsychologycanmakeasignificantcontributionintermsofmanagingresidentialwaterdemandespeciallyinplaceswithoutmeteredsupply ofwater(forexample,meteredwatersupplyisinplaceintheUnited Kingdomonlyforlimitednumberofhousesandfornewhouses).
Waterdemandmanagementorwaterconservationbehaviorrelatesto actionsthateitherreducetheamountofwatertobeusedorincreasethe efficiencyofwatertobeusedforanypurpose.Therearetwotypesofwater conservationbehaviors,namely,efficiencybehaviorsandcurtailmentbehaviors.Installationofwatersavingshowerheadsorrainwatertankor considering cleanvessels/reactorsonlywhenneeded inmanufacturingprocesses (forexample,indairyordyeindustries)facilitatingongoingwatersavings refertoefficiencybehaviors(Gerogiadisetal.,2000; Ahmetovicetal., 2010; RussellandFielding,2010).Incontrast,curtailmentbehaviorsare linkedtoindividualactionsthatcanreducewaterwhilewashingclothes, takingshowers,brushingteeth,cleaningdishes,wateringthegarden,and washingthecar(RussellandFielding,2010).
1.4Freshwaterproductionbydesalinationprocesses
Theunderlyingprincipleofdesalinationprocessescanbedescribedby Fig.1.10 wheretheseawaterorbrackishwaterfeedwithacertainpercentageofsalinityissplitintotwoseparatestreamswiththeaidofenergy. Thedesalinatedstreamisthedesiredproduct(freshwater)streammeeting specifiedamountofsaltandthehighlyconcentratedbrinestreamisthe wasteproductstreamtobedisposedof. Fig.1.11 showsthesourcesofwater usedindesalinationplants,withseawaterbeingthelargestvolumeofwater thatundergoesdesalinationtreatmenttobecomedrinkableandbrackish waterbeingthesecondlargest. Table1.3 showsthetypicalcompositionof seawaterwithasalinityof36,000ppm.Thesalinityisthetotalsalt
Rawwatersourcesusedindesalinationplants. (Adaptedfrom Zhouand Tol(2005).)
Figure1.10 Generalrepresentationofadesalinationprocess.
Figure1.11
Table1.3 Compositionofasampleofseawater.
Adaptedfrom El-DessoukyandEttouney(2002)
concentration,whichisequaltothequantityofdrysolidsperkilogramor literofseawater(g/L).Salinitycanalsobeexpressedaspartspermillion (ppm).Sinceallthesaltsinwaterarealmostcompletelydissociated,itis importanttoknowtheconcentrationofthoseions.However,thechemical compositionofoceansandseasisnotconstantanddependsonthelocation. Forthatreason,differentseawatershavedifferentcompositionandtemperature.Theionspresentinthelargestamountarethesodiumand chlorineones;however,othersaltsaredissolvedintheseawaterapartfrom thesodiumchloride(Filippini,2018). Table1.4 showstheclassificationof watersourcesbasedontotaldissolvedsolids.Note,therearelargevolumes ofbrackishwaterinChina.By2030Chinaissettohaveawatershortageof 60billioncubicmeters;thereforetheChinesegovernmenthasincreased
Table1.4 Classificationofwatersourcesintermsofquantityofdissolvedsolids (Filippini,2018).
WaterclassificationTotaldissolvedsolids
High-qualitydrinkablewatera <200ppm
Drinkablewatera 200 500ppm
Freshwater500 1,000ppm
Mildlybrackishwater1,000 5,000ppm
Moderatelybrackishwater5,000 15,000ppm
Heavilybrackishwater15,000 32,000ppm
Lowsalinityseawater32,000 37,000ppm
Highsalinityseawater >37,000 aAssuggestedbytheWorldHealthOrganisation(WHO,2011).
