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Water Purification in the Global South

Permanent Link: http://ncf.sobek.ufl.edu/NCFE004427/00001

Material Information

Title: Water Purification in the Global South
Physical Description: Book
Language: English
Creator: Patrick, Megan
Publisher: New College of Florida
Place of Publication: Sarasota, Fla.
Creation Date: 2011
Publication Date: 2011

Subjects

Subjects / Keywords: Water Purification
Development
Global South
Genre: bibliography   ( marcgt )
theses   ( marcgt )
government publication (state, provincial, terriorial, dependent)   ( marcgt )
born-digital   ( sobekcm )
Electronic Thesis or Dissertation

Notes

Abstract: The past few decades have marked an international effort to provide improved water sources, and development projects have become increasingly interdisciplinary. After careful consideration of the problem, an appropriate framework through which to view the effectiveness of design and implementation is determined to be based on a synthesis of the natural sciences, theoretical anthropological critiques of development, and real world experiences. To test the feasibility of reproducing an manganese-oxide coated filter based on an Indian design, coated sand gathered from a Florida site is tested for its ability to remove zinc. The failure of the sand to maintain its structure suggests that sand-coated water projects must be tailored locally, as do the conclusions from both real world and theoretical analysis. Furthermore, technical solutions may prevent underlying structural problems from being addressed, and in an issue that falls under the realm of domestic care, solutions which are not based on gender relations may have detrimental impacts for women. Challenges encountered in real world implementation of a January 2011 trip to northern Honduras with a student chapter of the non-profit organization Engineers Without Borders include limits on labor force, finances, environment, and social infrastructure.
Statement of Responsibility: by Megan Patrick
Thesis: Thesis (B.A.) -- New College of Florida, 2011
Electronic Access: RESTRICTED TO NCF STUDENTS, STAFF, FACULTY, AND ON-CAMPUS USE
Bibliography: Includes bibliographical references.
Source of Description: This bibliographic record is available under the Creative Commons CC0 public domain dedication. The New College of Florida, as creator of this bibliographic record, has waived all rights to it worldwide under copyright law, including all related and neighboring rights, to the extent allowed by law.
Local: Faculty Sponsor: Sendova, Mariana

Record Information

Source Institution: New College of Florida
Holding Location: New College of Florida
Rights Management: Applicable rights reserved.
Classification: local - S.T. 2011 P3
System ID: NCFE004427:00001

Permanent Link: http://ncf.sobek.ufl.edu/NCFE004427/00001

Material Information

Title: Water Purification in the Global South
Physical Description: Book
Language: English
Creator: Patrick, Megan
Publisher: New College of Florida
Place of Publication: Sarasota, Fla.
Creation Date: 2011
Publication Date: 2011

Subjects

Subjects / Keywords: Water Purification
Development
Global South
Genre: bibliography   ( marcgt )
theses   ( marcgt )
government publication (state, provincial, terriorial, dependent)   ( marcgt )
born-digital   ( sobekcm )
Electronic Thesis or Dissertation

Notes

Abstract: The past few decades have marked an international effort to provide improved water sources, and development projects have become increasingly interdisciplinary. After careful consideration of the problem, an appropriate framework through which to view the effectiveness of design and implementation is determined to be based on a synthesis of the natural sciences, theoretical anthropological critiques of development, and real world experiences. To test the feasibility of reproducing an manganese-oxide coated filter based on an Indian design, coated sand gathered from a Florida site is tested for its ability to remove zinc. The failure of the sand to maintain its structure suggests that sand-coated water projects must be tailored locally, as do the conclusions from both real world and theoretical analysis. Furthermore, technical solutions may prevent underlying structural problems from being addressed, and in an issue that falls under the realm of domestic care, solutions which are not based on gender relations may have detrimental impacts for women. Challenges encountered in real world implementation of a January 2011 trip to northern Honduras with a student chapter of the non-profit organization Engineers Without Borders include limits on labor force, finances, environment, and social infrastructure.
Statement of Responsibility: by Megan Patrick
Thesis: Thesis (B.A.) -- New College of Florida, 2011
Electronic Access: RESTRICTED TO NCF STUDENTS, STAFF, FACULTY, AND ON-CAMPUS USE
Bibliography: Includes bibliographical references.
Source of Description: This bibliographic record is available under the Creative Commons CC0 public domain dedication. The New College of Florida, as creator of this bibliographic record, has waived all rights to it worldwide under copyright law, including all related and neighboring rights, to the extent allowed by law.
Local: Faculty Sponsor: Sendova, Mariana

Record Information

Source Institution: New College of Florida
Holding Location: New College of Florida
Rights Management: Applicable rights reserved.
Classification: local - S.T. 2011 P3
System ID: NCFE004427:00001


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WaterPuricationintheGlobalSouth MeaganCheritaPatrick May16,2011 AThesis SubmittedtotheDivisionofNaturalSciences NewCollegeofFlorida Inpartialfulllmentoftherequirementsforthedegree BachelorsofArts UnderthesponsorshipofDr.MarianaSendova 1

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WaterPurificationintheGlobalSouth MeaganCheritaPatrick NewCollegeofFlorida,2011 Abstract Thepastfewdecadeshavemarkedaninternationale!orttopr ovide improvedwatersources,anddevelopmentprojectshavebeco meincreasinglyinterdisciplinary.Aftercarefulconsiderationoft heproblem,an appropriateframeworkthroughwhichtoviewthee!ectivene ssofdesign andimplementationisdeterminedtobebasedonasynthesiso fthenaturalsciences,theoreticalanthropologicalcritiquesofde velopment,andreal worldexperiences.Totestthefeasibilityofreproducinga nmanganeseoxidecoatedlterbasedonanIndiandesign,coatedsandgat heredfroma Floridasiteistestedforitsabilitytoremovezinc.Thefai lureofthesand tomaintainitsstructuresuggeststhatsand-coatedwaterp rojectsmust betailoredlocally,asdotheconclusionsfrombothrealwor ldandtheoreticalanalysis.Furthermore,technicalsolutionsmaypr eventunderlying structuralproblemsfrombeingaddressed,andinanissueth atfallsunder therealmofdomesticcare,solutionswhicharenotbasedong enderrelationsmayhavedetrimentalimpactsforwomen.Challengesen countered inrealworldimplementationofaJanuary2011triptonorthe rnHonduras withastudentchapterofthenon-protorganizationEngine ersWithout Bordersincludelimitsonlaborforce,nances,environmen t,andsocial infrastructure. Dr.MarianaSendova NaturalSciences 2

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Thisundergraduatethesisisdedicatedtomybaccalaureate committeeatNewCollegeofFloridaandtoPatrickMcCarthyofthe ChemistryLab,withoutwhomtheexperimentportionwouldnotex ist.Tomythesissponsor,ProfessorMarianaSendova,whorevi ewed conceptswithmeweeklyandcameupwithcreativeideastoexp lore. ToProfessorUziBaram,whoapproachedthethesisandourmee tings withenthusiasm,andtoProfessorGeorgeRuppeiner,whosesu pport duringhisyearsasmyacademicadvisorhasbeeninvaluable. 3

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Contents IIntroduction 8 IITheFundamentalsofWater10 1ASmall-ScaleLook 11 1.1HydrogenBonding..........................12 2pH 13 3InteractionsinWater 13 3.1ContaminatedWaterasaColloidalDispersion......... .13 3.2ClassicDVLOTheory........................13 3.3ExtendedDVLOTheory.......................14 IIIAnOverviewofPuricationMethods15 4Coagulation/Flocculation 15 5Adsorption 16 5.0.1vanderWaalsForce.....................17 5.1Clay..................................17 5.2ActivatedCarbon...........................19 5.3Biopolymers..............................20 5.3.1Cellulose...........................21 5.3.2ChitinandChitosan.....................22 5.3.3Alginate............................23 5.3.4PeatMoss...........................23 5.4NaturalZeolites............................24 5.5IndustrialWaste...........................25 5.6WastePolysterene..........................26 5.7OtherAdsorbents...........................27 6MembraneProcesses 28 6.1MembraneFilters...........................29 6.2Osmosis................................30 6.2.1ReverseOsmosis.......................30 6.2.2ForwardOsmosis.......................31 7IonExchange 31 4

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8MagneticallyAssistedProcesses31 8.0.3High-GradientMagneticSeparation(HGMS).......31 8.0.4MagneticModication....................31 9BiologicalandPhysicalMethods32 9.1Boiling.................................32 9.2Evaporation/Distillation.......................3 2 9.3SoilBiotechnology(SBT)......................34 9.4SandFilters..............................35 9.4.1RapidGravitySandFilters.................35 9.4.2RapidPressureSandFilter.................35 9.4.3SlowSandFilter.......................35 10DirectChemicalMethods 36 10.1Chlorine................................36 10.2ChlorineDioxide...........................38 10.3Iodine.................................38 11CatalyticProcesses 38 11.1Oxidation...............................39 11.2Solar-assistedOxidation.......................3 9 11.3Photo-assistedOxidation......................40 11.3.1 TiO 2 ..............................40 11.4Ozonation...............................40 11.4.1HeterogeneousCatalyticOzonation.............4 1 11.5Electrocatalysis............................41 11.6Electro-FentonMethods.......................41 11.7Photo-electricProcess........................42 12LocalMethods 42 12.1SouthAmerica............................42 12.2Asia..................................42 12.2.1India..............................42 12.2.2Iran..............................43 12.2.3Indonesia...........................43 12.3Africa.................................43 12.3.1Egypt.............................43 12.3.2Sudan.............................43 12.3.3Mali..............................44 12.3.4Nigeria............................44 12.3.5Niger.............................45 12.3.6Kenya.............................45 IVMethodsofCharacterization46 5

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13Bacteria 46 13.1EscherichiacoliandTotalColiforms............... .46 14Protozoa 47 14.1CryptosporidiumandGiardia....................47 15Viruses 48 15.1Coliphages...............................48 16Inorganics 49 16.1SpectroscopicMethods........................49 16.1.1AbsorptionSpectroscopy..................51 16.1.2UV-VisibleSpectroscopy...................52 16.1.3Infrared(IR)Spectroscopy.................53 16.1.4X-RayFlourescence(XRF).................53 16.1.5Inductively-CoupledPlasmaMassSpectrometry(ICP -MS)53 16.2Conductivity.............................53 16.3IonTestStrips............................53 VApplicationofMethods54 17Implementation:SystemsandInfrastructure54 17.1CollectiveSystems..........................54 17.1.1WellDrilling.........................54 17.1.2SurfaceWaterCollection..................55 17.2IndividualSystems..........................55 17.2.1RainwaterHarvestingfromRoofs..............55 17.2.2ClayPots...........................56 17.2.3Point-Of-Use(POU)Contamination............57 18EthicalIssues:WaterasaHumanRight58 19MoralityofWater:AnAnthropologicalLens59 20GenderConsiderations 61 21SustainabilityandAppropriateTechnology64 22ActiveInternationalAgencies 64 VICaseStudy:Honduras68 VIIExperiment 70 23Purpose 70 6

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24InstrumentsandMaterials 70 24.1Procedure...............................71 24.2PreparationofSand.........................72 24.3CoatingtheSand...........................72 24.4PreparationofZincSolution.....................7 3 24.5PreparationoftheFilters......................73 25ResultsandConclusion 74 VIIIConclusion 77 7

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PartI Introduction Waterissovitaltoourbodiesthatwetakeinmoreofitonadai lybasisthan allothermaterialscombined[34].Giventhisfundamentalb iologicalrelianceon water,wemustbealarmedaspotablewaterbecomesincreasin glymorescarce. DocumentariesandnewsstoriesrecentlyreleasedintheUni tedStatesexplain thatasourglobalpopulationexpands,ratesofpollutionfr omindustryincrease andvirginlanddisappears,theamountofpotablewaterquic klydecreases.But whileweasanationponderthepossibilityofupcomingwater shortages,for manythelackofcleanwaterisalreadyareality.Nowhereist hislackofthe preciousresourcefeltthanintheGlobalSouth-thetermuse dinthisthesisto describethecollectionofcountriesknownotherwiseasdev elopingnations. In2002,theUnitedNations(UN)namedtheyears2005-2010th eInternational'WaterforLife'decade,inane!orttomeettheMilenn iumDevelopment Goalofhalvingtheamountofpeopleworldwidewithoutsusta inableaccessto safedrinkingwater.TheUNreportsthatprogresshasbeenma de,butthatas weenterthesecondhalfofthedecade,theinternationalcom munityisbehindon itsgoal.In2002whentheMilenniumDevelopmentGoalswere nalized,WHO studiesshowed17%ofthepopulation,or1.1billionpeople[ 47]lackedaccessto improvedwatersources.Fiveyearslater,thenumberscited byWHOarelower at884millionpeoplewithaccesstocleandrinkingwater,or 13%oftheglobal population,butareinsu"cienttoachievetheMilenniumDev elopmentGoalof 8.5%inthenextveyears[48].Howthesenumbersarequanti edissubjectto critiqueasevenwithaccesstoacommunityprotectedwaters ource,watermay notbeavailableinthehomeormaybecontaminatedduringtra nsport. Themethodsofachievingthisgoalmaybeconsideredjustasi mportantas theendresult.Whileitisarguablethatglobalmodelsofdev elopmentprojects areinappropriateandine!ectualwhendevelopmentagencie strytotailorthem totalocalsituation,itisnotarguablethattheimplement ationofwaterpuricationprojectsmustbelocallybasedonavailableresource s.Waterisdi"cult andexpensivetotransport,andsoitcannotbeshippedinlik efoodaid;contaminationofthewatervariesgeographically;andmethods ofcharacterization donotworkuniversally.Potentialsourcesofwaterrestric tthepossibilitesfor waterpuricationfactorswhichincluderainfall,underg roundwatertables, andabove-groundwatersources. Clearly,nowaterpuricationmodelcanbedevelopedto"x" thecurrent famineofpotablewateronaglobalscale,particularlyifso lutionsarenotfabricatedinanappropriatemoralandscienticframework.Th epurposeofthis thesisistobegintodevelopthatframeworkbystitchingtog etheramultidisciplinarysurveyofwaterpuricationintheGlobalSout h.Istartwitha textbook-likedescriptionofmanymethodsofwaterpurica tionandcharacterization,andprogresstoissuesinvolvedintheimplementat ionofwaterdevelopmentprojects.Ihavechosenmodernanthropologyasalens throughwhich 8

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toviewthemoralframework.Branchesofanthropologycriti quedevelopment fromastructuralviolenceandhumanrightspointofview,th roughtheanalysis ofgenderrelationsbeyondjusttheWesternconceptionoffe minism,andwith theideologybehindproducingsustainablesolutions.Furt hermore,ananthropologicallensbenetstheframeworkinunderstandingwate rscarcitynotasa biologicalfact,butasareectionofcomplicatedsocialre alitiesthatrequire specicregionalattention. Furthermore,Itrytoreproduceanexperimentdevelopedloc allyinIndia, byIndianscientists,thatuseslocalmaterials;andIrepor tonmyimpressions fromasiteassessmenttripforadevelopmentprojectbyanEn gineersWithout BordersstudentchapterinHonduras. 9

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PartII TheFundamentalsofWater Fig 0.1TheWaterCycle[4] Theworld'swatersupplyisfoundinallvestagesofthehydr ologicalcycle[34]: condensation,precipitation,inltration,runo!,andeva poration.Allstagesof thehydrologicalcycleprovidepotentialsourcesofpotabl ewater,thoughsome aremoreaccessiblethanothers.Waterhasmanyuniqueprope rtieswhichcan betracedbacktoitschemicalstructure.Thefollowingtabl eisexerptedfrom achemistrytextbook[41],anditdemonstratessomeofthese propertiesand theirsignicance.Thefollowingchaptergoesintomoredep thaboutthescience behindtheseproperties. 10

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Property E !ectsandSignicance Excellentsolvent Transportofnutrientsandwaste products,makingbiologicalprocesses possibleinanaqueousmedium Highestdielectricconstantofanypure liquid Highsolubilityofionicsubstancesand theirionizationinsolution Highersurfacetensionthananyother liquid Controllingfactorinphysiology; governsdropandsurfacephenomenom Transparenttovisibleand longer-wavelengthfractionof ultraviolet(UV)light Controllingfactorinphysiology; governsdropandsurfacephenomena Maximumdensityasaliquidat 4 o C Iceoats;verticalcirculationrestricted instratiedbodiesofwater Higherheatofevaporationthanany othermaterial Determinestransferofheatandwater moleculesbetweentheatmosphereand bodiesofwater Higherlatentheatoffusionthanany otherliquidexceptammonia Temperaturestabilizedatthefreezing point Higherheatcapacitythananyother liquidexceptammonia Stabilizationoftemperaturesof organismsandgeographicalregions. 1ASmall-ScaleLook Figure 1.1FiveWaterMoleculesConnectedbyHydrogenBonds[63] Onanatomiclevel,amoleculeofwateriscomposedoftwohydr ogenatoms andanoxygenatom.Itiselectricallyneutral,asitspositi velychargednucleiis balancedbynegatively-chargedelectronsthatsurroundth eatom.Thehydrogen 11

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andoxygenatomsarearebondedcovalently,meaningthatthe electronsare sharedequallyinthebond. Eventhoughthebondsarecovalent,theoxygenatomismuchmo reelectronegativethanthehydrogenatommeaningoxygenstrongl yattractselectronsrelativetootheratomsontheperiodictable.Thearra ngementofthese atomsisdeterminedbyatheoryknownastheValence-ShellEl ectron-PairRepulsionTheory(VSEPR);thevalenceshellbeingtheoutermo stshellofpairsof electronsofcomplementaryoppositespinsarrangedinprob abilityclouds[34]. VSEPRisbasedonthesimpleideathatlikechargestorepelea chother.It statesthatthedirectionsofthebondsofthecentralatom(o xygen)arearranged insuchawaysothatneighboringcloudsofelectronsareasfa rawayaspossible fromeachother[34].DuetophenomenomdescribedbyVSEPR,t hehydrogen atomsarelocatedatanangleof 104 5 o degreesapart.Theresultisthatalthough themoleculeisoverallelectricallyneutral,ithasaposit ive(lesselectrons)and negativeend(moreelectrons). Thisasymmetricalstructureofthehydrogenatommeansthat waterisa polarmolecule,asopposedtoanon-polarmoleculeinwhichc hargeisevenly distributed.Apolarmoleculehasapermanentdipolemoment ,witha +and a -siderepresentingthepositivelyandnegativecharge(Fig .1)[34]. 1.1HydrogenBonding Whilecovalentbondsformstrongbridgesbetweentheatomsi nthemolecule, hydrogenbondsformrelativelyweakbridgesbetweenwaterm oleculeswhich areonly5%asstrongascovalentbonds[34].Thesebridgesar etheresultof forcesofattractionbetweenthe +side(thehydrogenatoms),andthe -side (theoxygenatoms)ofthewatermolecule(Fig1.1).Whilethe sebridgesmay seemweakincomparisontothecovalentbondsofthemolecule ,manyofthe uniquepropertiesofwaterareduetohydrogenbonding. Onepropertyduetohydrogenbondingistheextremelyhighsp ecicheat capacitycomparedtootherliquids.Thespeciccapacityis theamountof energyrequiredtoincreasethetemperatureofonegramofli quidbyonedegree C. Anotherpropertyduetohydrogenbondingisthestrongsurfa cetension,in whichthesurfaceofthewateractsasifitwereathinelastic membrane[34]. Intheinteriorofthewater,watermoleculesarepulledstro nglytowardseach otherbythehydrogenbonding,andthereisnoequivalentfor cefromtheair. Thisisalsowhywhenwaterisonnonpolarsurfaceslikewaxit formsintobeads whilewhenitisonapolarsurfacelikeglass,itspreadsout. Thepolarsurface oftheglassprovidesenoughattractiontoovercomethesurf acetensionwhich wouldotherwisemakethewaterformdroplets[34]. 12

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2pH pHisameasureoftheacidityorbasicityofanaqueoussoluti onmadeby approximatingthenegativebase-tenlogarithmofthemolar concentrationof dissolvedHydroniumions( H 3 O + ).Itisunderstoodmorefundamentallyasthe measureofhydrogenionsthatresultfromthedisassociatio nofwater: H 2 O H + + OH ThescaleofpHrangesfrom0(veryacidic-manyhydrogenions )and14 (verybasic-manyhydroxideions).Potablewaterhasaneutr alpHof7at roomtemperature( 25 o C ),whichisthebenchmarkbetweenacidicandbasic solutions. Acidityisthecapacityofwatertoneutralizehydroxideion s( OH ),and acidicwaterisinfrequentlyencounteredexceptduetocase sofhighamounts ofpollutionofmainlyweakacidssuchas H 2 PO 4 CO 2 H 2 S proteins,fatty acids,andacidicmetalionslike Fe 3+ [42].Minewatercanbeveryacidicas thehydratedmetalionsbehaveasacids,suchasinthecaseof hydratediron (III): Fe ( H 2 O ) 3+ 6 "# Fe ( OH ) 3 ( s )+3 H + +3 H 2 O 3InteractionsinWater 3.1ContaminatedWaterasaColloidalDispersion Dependingonthesizeofthecontaminants,awatermixtureca nbecharacterized asasolution,acolloidaldispersion,orasuspension(inwh ichtheparticlesare over1000nmindiameter).Colloidaldispersionsareliquid scontaminatedwith largeclustersofionsormoleculeslargeenoughtoreectan dscatterincoming light,butnotlargeenoughtomakeasuspension.Thisscatte ringoflightin colloidaldispersionsisknownastheTyndalle!ect,anditi swhyacolloidal dispersionwilloftenappearcloudy[34].Theunevenbu!eri ngofthecolloidal particlesbythewaterisdescribedbyBrownianmotion,whic hcounteractsthe gravitationalforceandpreventstheparticlesfromsettli ngtothebottom[34]. Coagulation,amethodofwaterpurication,worksbybringi ngtheclustersof ionsormoleculestogethersothattheybecomemassiveenoug hthattheforce ofgravitywillcausethemtosettletothebotom. 3.2ClassicDVLOTheory Startinginthe1940's,theinteractionenergiesbetweenpa rticlesinaliquid werethoughttoobeytheDLVO(DerjaguinandLandau(1941-US SR)theory, andVerweyandOverbeek(1948Netherlands),whichdescrib esrepulsionby electrostaticenergiesandLondon-vanderWaalsattractio nenergiesasafunction ofinter-particledistance[59].Thetheoryincludeselect ricaldouble-layer forces,whichdescribetheforcesduetothedouble-layerst ructurethatforms onthesurfaceofsomethingwhichisplacedintheliquid.The rstlayeris madeofpositiveornegativelychargedionswhichadsorbont othesurface,and 13

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thesecondlayerisionsattractedtotherstsurfacelayerv iatheCoulomb force.TheColoumbforceinitsmostbasicform(outsideofth ewater)isthe interactionbetweentwocharges q 1 and q 2 locatedinspace: F = 1 k q 1 q 2 r 2 ,where kisaconstantandristhedistancebetweenthecharges. 3.3ExtendedDVLOTheory UnlikenonpolarLWsystems,inpolarsystemsidenticalbiop olymers,particles orcells,repeleachotherduetoLewis-acid-baserepulsion s.VanOsswritesthat Lewisacidbaserepulsionsarethemostsignicantfactorof particlebehaviorin water,whichcanbeshownbythevalueseachinputtowardsthe freeenergyof water. Theresultofthispolarattractionbetweenwatermolecules meansthat allnon-polarmoleculesgrouptogether,knownasthe"hydro phobice!ect," asaresultoftheLewisA-B(acid-base)freeenergyofcohesi onamongwater molecules[59].Thehydrophobice!ecta!ectsbothhydropho bicandhydrophilic molecules,thoughiftheparticlesareveryhydrophilicthe ntheycanbecomeso stronglyhydratedthattheycauseanethydrophilicrepulsi oncalled"hydration pressure,"inwhichwatermoleculesrepeleachother.Inour body,hydration pressureiswhatkeepsbloodcellsfromclumpingtogether[5 9]. 14

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PartIII AnOverviewofPurication Methods Thereexistsawiderangeofpuricationmethods,andfactor swhichinuence thechoiceofmethodsincludetheamountofdisposableresou rcesandpublic support,theavailabilityoffreshwater,andthetypeofbio logicalandchemicalcontaminationofthewater.IntheUnitedStates,conve ntionalmethods involvedisinfecting,decontaminating,anddesalinating inlargechemicaltreatmentplants.Theoverallresultsoftheseintensivetreatme ntsaresludge,brines, andtoxicwasteswhichcontaminatesurroundingfreshwater sources,further contributingtotheproblemofcleanwateravailability[30 ].Thefollowingis abreakdownofmanyofthemethodsofwaterpurication,thou ghitisbyno meansacompletelist. 4Coagulation/Flocculation Fig 4.1:Coagulation[29] Oneoftheoldestformsofwaterpuricationisocculation, inwhichcolloids comeoutofsuspensionsintheformof"ocs"orakessothatt heybecome massiveenoughthatgravitycanovercomebrownianmotion.W hiletheyare sometimesusedinterchangeably,occulationistheformat ionoflargermasses fromsuspendeddestabilizedparticles,andcoagulationis thedestabilizationof thoseparticlesbyneutralizingtheirchargessotheynolon gerrepeleachother. TheSchulze-Hardyphenonom,takenfromthescientistsSchu zle(1882,1883), andHardy(1900),istheoccurrenceofstableaqueoussuspen sions("sols")of negativelycharged AsS 2 ,Au,orAgIparticlesthatcanbeocculatedbythe admixtureofsaltswithplurivalentcounter-ions(cations canbeusedhere)so thatthehigherthevalencyoftheaddedcounter-ions,thele ssofthemisneeded 15

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toachieveocculation[59].Thiswasconrmedexperimenta llyin1952byOverbeek[59].Thereasonthatitoccursisthatifoneinducesade creaseinthe potentialofelectricallychargedhydrophilicparticles, thesurfaceschangefrom hydrophilictohydrophobic,causingthemtoagglomerateth roughhydrophobic attractionwhentheyareimmersedinwater[59].The -potentialisthetermfor electrokineticpotentialincolloidalsystems,orthepote ntialdi!erencebetween thedispersionmediumandthelayerofuidattachedtothedi spersedparticle [59]. Thestabilityofsuspensionsofintrinsicallyelectricall yneutralhydrophilic particlessuchaspolyethyleneoxide-coatedparticlesisn ota!ectedbypHchange. Thereisnofundamentaldi!erencebetweenthestabilizatio nofaqueoussuspensionsofelectricallychargedinorganicparticlesandthes tabilizationofnoncharged,initiallyhydrophobicparticlesbytheadsorptio northeelectrostatic orcovalentattachmentofelectricallychargedsurfactant orofhydrophilicpolymermolecules.Manyparticlescanspontaneouslyformstabl esuspensionsin water(whentheyarehydrophilicorclosetohydrophilic)su chassilicaparticles andclayparticles(mostsmectites).Stabilizationcanbea chievedbycoating hydrophobicparticleswithsomethinghydrophilic[59]. Saltsofaluminumandironarefrequentlyusedinwatertreat mentascoagulants[42],suchas Al 2 ( SO 4 ) 3 18 H 2 O .Thealuminumionshydrolyzesby reactionsthatconsumealkalinityinthewatersuchas: Al ( H 2 O ) 3+ 6 +3 HCO 3 AL ( OH ) 3 ( s )+6 H 2 O .Thegelatinoushydroxidethatformscarriesawaythedispersedcolloidalsolidsasitsettlestothebottom. 5Adsorption Adsorptioniswhenatomsormoleculesattachtoa2-dimensio nalsurfacedue toforcessuchastheelectrostaticforce,vanderWaalsforc e,andchemical bonds(adherence).Therearetwomaintypesofadsorptionpr ocesses:physical, whicharedominantatlowertemperatures;andchemical,whi charegenerally irreversiblebecausechemicalinteractionsareinvolvedb etweentheadsorbate andadsorbentmoiety. ThephysicaladsorptionprocessinvolvestheVanderWaalsf orce,theweakestofthefourintermolecularforces.Factorsa!ectingche micaladsorptionincludepH,temperature,adsorbentquality,andparticlesiz e[54].TheDLVO theoryofcolloidstabilityintroducedinthesecondchapte risoftenusedtodescribebacterialsorption.Adsorptionismodeledbyadsorp tionisotherms,which describethesorptionofamaterialataconstanttemperatur e[19].Thesemodels areobtainedbyregressionanalysis,andthemostcommoniso thermsusedare thelinearisotherm,theFreundlichisotherm,theLangmuir isotherm,andthe BETmodel[19].Adsorptivecapacitygenerallyincreaseswi thanincreaseof surfaceareaoftheadsorbent. Thicklterslikecarbonorceramicsareporousmaterialsth atlterthe waterusingadsorption,butadsorbentsarealsooftensuspe ndedinthewater. Adsorbentsincludereadilyavailableobjectssuchascocon ut,jutestick,rice 16

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husk,bark,lignin,chitosan,deadbiomass,xanthate,zeol ite,andpeatmoss [52]. Thephenomenomofadsorptionisinvolvedincoagulationand occulation. Inturbidwaters,negativelychargedwatercolloidsareeas ilyocculatedby cationiccoagulants,butpositivelychargedparticlescan alsobeocculatedby anionicpolymersinthepresenceofdissolvedsalts,usuall ydivalentdissolved salts[17].Thepolymerwillformbridges,regardlessofits charge,byadsorption ofsegmentsofitschainoncolloidalparticles,andoccula tionwilltakeplace onlyiftheparticlesurfacesareonlypartiallycoveredwit hadsorbedpolymer [17].Ifthereistoomuchpolymer,thentheparticlesarerestabilized[17]. 5.0.1vanderWaalsForce Inadditiontothehydrogenbondingbetweenwatermolecules ,therearethe interactionsbetweenthedipoleswhichareimportantinads orption.Dipole interactionsarecollectivelycalledthevanderWaalsforc es,thoughtheycanbe brokendownintothreedi!erenttypes[59]: 1.VanderWaals-KeesomDiscoveredin1915bythescientist Keesom,these arealsoknownasdipole-dipole,ororientationforces. 2.VanderWaals-DebyeDiscoveredin1920bythescientistD ebye,thisare alsocalleddipole-induceddipole,orinductionforces. 3.VanderWaals-LondonDiscoveredbyLondonin1930,these arealso calleductuatingdipole-induceddipoleforces,ordisper sionforces. ThevanderWaalsforceswiththegreateste!ectonwaterinte ractionsarethe Londonforces.Thereisarapiddie-o!inthestrengthofthev anderWaals forceonthemicroscopiclevel,asitdecreasesasafunction of 1 ( distance ) 6 This die-o!ismuchweakeronthemacroscopiclevel,astheforced ecaysonlyata valueof 1 ( distance ) betweensphericalbodies[59],asrstpositedin1955bythe scientistLifshitz.Thiswasconrmedin1984,whenChaudhu rydemonstrated thermodynamicallythatthemacroscopic-scalevanderWaal senergiesdecayed slowerasafunctionofdistance( 1 ( distance ) fortwospheresandforasphereand aatplate,and 1 ( distance ) 2 fortwoatparallelplates).Forthisreason,vander WaalsforcesonthemacroscopiclevelarecalledLifshitz-v anderWaals(LW) energies[59],andtheyareconsiderednon-polar. 5.1Clay Claypotshavebeenusedforcenturiesforwaterpurication .Claymakesagood low-costandreadilyavailableadsorbent,asithasexcelle ntcationexchange properties,ahighsurfacearea,andnetnegativechargewhi chattractspositivelychargedheavymetals.Claysbindtocationslike Ca 2+ Mg 2+ ,K + Na + and NH 4 [42].Thethreemajorgroupsofclaymineralsaremontmorill onite 17

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( Al 2 ( OH ) 2 Si 4 O 10 ) ,illite ( K,H 3 O )( Al,Mg,Fe ) 2 ( Si,Al ) 4 O 10 [( OH ) 2 ( H 2 O )] and kaolinite ( Al 2 Si 2 O 5 ( OH ) 4 ) 4 [42]. Clayshavelayeredstructuresmadeofsheetsofsiliconoxid e(madeoftetrahedraeachsiliconatomissurroundedbyfouroxygenatoms, threeofwhich aresharewithsilicontoformpartofothertetrahedra)whic halternatewith sheetsofaluminumoxide(madeofoctahedrainwhicheachalu minumatom issurroundedbysixoxygenatoms)[42].Thus,thesiliconox idesheetsare knownasthetetrahedralsheets,andthealuminumoxideshee tsareknownas theoctahedralsheet[42].Clayscanbeclassiedaseithert wo-layerclaysand adjacentoctrahedralsheet,orthree-layerclays.Twolaye r-clayshaveoxygen atomssharedbetweenatetrahedralsheet.Three-layerclay shaveanoctahedral sheetthatsharesoxygenatomswithtetrahedralsheetsonbo thsides[42]. Montmorillonitehasthehighestcationexchangecapacity, withthepresence ofanionicsurfactantsenhancingitse!ectivity[21].Itha sthepropertythatit canabsorblargequantitiesofwaterbetweenlayers,whichc ausestheclayto swell[42].Chinaclay-yash,wollastonite,yash,andChi naclay-wollastonite haveallbeenevaluatedfortheremovalofcopper[21].Inadd ition,bentoniteis amixtureofclay,silt,andsandwhichhasbeenstudiedinthe removalofheavy metalssuchascadmiumandzinc. Clayworksasacoagulantitsmainfunctionbeingtoincreas eparticle collisions[17].StudiesshowthatMontmorilloniteandkao linite(bothalumininumsilicates),aremoste!ectiveinremovingthepoliovir usdependingonthe concentrationofsodiumorcalciumcationsinthewater.Max imumadsorption isachievedwhenapproximately10timesmoremonovalentsod iumionsthan divalentcalciumionswereinthewater[17]. Thebiggestdrawbacktosuspendedclayparticlesisthatlik esuspended activatedcarbonparticles,theycanbedi"culttoseparate .Inaddition,possible negativee!ectsofwatertreatedwithclayincludeanincrea seintraceelements likeCrandMn[17].Claymineralscanbemodiedwithironoxi de,which achievestwokindsofmagneticparticlemodiedadsorbents -bentonite-iron oxideandzeolite-ironoxide-bothofwhicharee!ectiveinm etalionremoval ( Ni + 2 ,Cu 2 ,Cd + 2 )[51].LargedepositsofclaycanbefoundintheUS,Lithuani a, Georgia,andKazakhstan[21]. 18

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5.2ActivatedCarbon Figure 5.2.1Eightallotropesofcarbon:a)Diamond,b)Graphite,c )Lonsdaleite,d)C 60 (Buckminsterfullereneorbuckyball),e)C 540 ,f)C 70 ,g) Amorphouscarbon,andh)single-walledcarbonnanotubeorb uckytube [2]. Activatedcarbonisoneofthemostwidelyusedtechniques.T wogeneraltypes aregranulatedactivatedcarbon(particlesof0.1-1mmindi ameter,andpowderedactivatedcarbon(50-100 # mindiameter).Activatedcarbone!ectiveness isduetoitshighsurfacearea,porousstructure,andsurfac ereactivityinwhich thecarbonatomsareleftinanarrangementwithattractions toorganiccompounds[42].Activatedcarbonishighlyinert,thermallyst ableandcanbeused overabroadpHrange,andchemicaltreatmentcanbeappliede asilytoincrease adsorptioncapacity,bymakingitgraphitic[51]. Theprecursortoactivatedcarbonisnon-graphitiziblecar bonwithaninitial isotropicstructure,like(g)intheabovegure.Itiscalle dnon-graphitizable carbonbecauseitcannotbetransformedintographiticcarb onsolelybyraising thetemperatureto 3027 o C atstandardatmosphericpressure.Thisprecursor isheateduntilitisgraphitizable,orabletobemadeintoth eallotropeof graphitebycharringtherawmaterialanaerobicallybelow 600 o C ,followedby anactivationstepofpartialoxidation[42].Theoxidation issometimesdown bycarbondioxideattemperaturesof 600 $ 700 o C ,orbywaterat 800 $ 900 o C [42]. CO 2 + C 2 CO (1) H 2 O + C H 2 + CO (2) 19

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Thehightemperaturesremovesolidmassandcreateporesint heirplace, creatingagreatersurfacearea.Theresultingactivatedca rbonisanarrayof disorderedmicrostructures[23].Activatedcarboncanbem adefromagricultural wastes,wood,andpetroleum,butismostcommonlymadefromb ituminouscoal [54].Bituminouscoalisanorganicsedimentaryrockcontai ningbitumenformed bycompressionofpeatbogmaterial. Activatingthecarboncanalsobeanexpensivetechnique.In addition,the powderedformposesafurtherproblem:itisdi"culttosepar atefromthewater afterpurication.Regenerationofexhaustedactivatedca rbonbychemicaland thermalmethodsisexpensiveandresultsinthelossofadsor bentmaterial[51]. Particlesofactivatedcarboncanalsobedi"culttoseparat efromaliquidby ltration,asthesmallsizecouldblockthelter.Powdered activatedcarbonfor thisreasonhasbeentraditionallydiscardedafterusealon gwithprocesssludge. Onewayofsolvingthisproblemis,likeclay,throughmagnet icmodicationof thecarbonadsorbentwithironoxides(especiallymagnetit e).Thepowdered activatedcarboncanthenbere-usedratherthanthrownaway [51]. Activatedcarboncanbemademorecheaplyfromreadilyfound materials, suchasricehusk,carbonizedwithsulfuricacid,knownasRi ceHuskCarbon (RHC)[21].Removale"ciencyincreaseswithadecreaseinch romiumconcentrationandtheadsorptionfollowstheFreundlichisotherm [21]. 5.3Biopolymers Biopolymersareorganicpolymersusuallyproducedbylivin gorganisms,suchas cellulose,starchandchitinwhicharelow-costandwidelya vailable,non-toxic, andbiodegradable.Biopolymershaveexcellentadsorption performancebecause theyhavealargenumberofactivefunctionalgroups.Themai ndi"cultyisthat theyareoftenusedinpowderedforms,whicharedi"culttose paratefromwater. Likecarbon,ifmagneticparticlesareintegrated,thenthe ymaybee"ciently separatedusingmagneticprocesses[51]. 20

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5.3.1Cellulose Figure 5.3.2.1[8] Cellulose( CH 10 O 5 )isthemostcommonlyusedbiopolymer.Inparticular, orangepeelcellulosehasbeenpreparedusingdi!erentchem icalreagentsas biosorbents.In2007,astudypublishedontheuseoforangep eelcellulosein thesorptionof Cd 2+ showedthattheoptimumpHforcadmiumsorptionwas 6[69]. 21

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5.3.2ChitinandChitosan Figure 5.3.2.1Chitin[1] Figure 5.3.2.2Chitosan Chitin( C 8 H 12 O 5 N )isthesecondmostcommonbiopolymeraftercellulose,and itisfoundintheexoskeletonsofshandcrustaceans.Alkal ineN-deacetylation ofchitinwillproducechitosan ( C 6 H 11 NO 4 ) .Chitosanisnotonlycheapbutalso bindswelltometalsandhasastructuresimilartocellulose [21].Inaddition, itisbiocompatible,biodegradable,andhasantibacterial properties[70].It isparticularlygoodatsorbingtransitionmetalssincecoo rdinationsitescan befoundonitsaminogroups[70].Itisalsoaparticularlyag oodoptionin countriessuchasJapan,China,andThailand,wherechitosa ncanbeproduced bytheshrimp,lobsterandcrabshellsfromtheshingindust ry[21].In1988, researchwasdonetodeterminethefeasibilityofchitosant oremovecadmium fromwater,anditwasdiscoveredthatithadanadsorptionca pacityof5.93 mgofcadmium/gramofchitosan[21].Chitosanhasbeenmoree ectivein 22

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theremovalofmercury,copper,nitrogen,andzinc.Recentl y,Chitinhasbeen usedasanadsorbentindeouridization.Toovercomesomeof theproblems ofnaturallyoccurringchitosan,ithasrecentlybeencoate doncalciumalginate tocreateCCCA(chitosancoatedcalciumalginate),andsili catocreateCCS (chitosancoatedsilica). 5.3.3Alginate [3] Alginatecanbegeneratedfrombrownseaweed,andconstitut es10-40%of allspeciesofbrownalgae[70].ItisalinearcopolymerofaL-guluronate(G) anda-D-mannuronate(M),andhasgelationpropertiesdueto itssimultaneous bindingofdivalentcationstodi!erentchangesoftheGbloc ks[70].Electronegativecavitiescanformthatarecapableofholdingthecatio nsthroughionic interactions,cross-linkingthestructureintoaboxwhich canholdthecations [70].A2008paperexploredthee!ectivenessofcalciumalgi nate,andfound thattheoptimumpHwas5[70]. 5.3.4PeatMoss Fig 5.3.4.1:Spaghnum[65] 23

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Fig 5.3.4.1:PeatMoss[64] PeatmossisthecompacteddecayedformofSphagnum,agenuso fbetween151 and350speciesofmossesfoundprimarilyinpeatbogs.Itcon tainsligninand cellulose,hasalargesurfacearea ( > 200 m 2 /g ),andishighlyporous.Research intotheabilityofoligotrophic(whicho!erslittletosust ainlife)andeutrophic (whicho!ersalottosustainlife)peattoabsorbheavymetal swasinvestigated startedin1986[21]. 5.4NaturalZeolites Figure 5.4.1BasicZeoliteStructure[68] Figure 5.4.2ZeolitePorousStructure[35] Naturalzeolitesareaclassofmineralsthathaveaporousst ructure(Fig.5.4.2). Theyarecrystallinealuminosilicates-tetrahedralmolec ules(Fig.5.4.3)ofsiliconandaluminumcomplexionsthatareconnectedbysharedo xygenatoms [21].Inparticular,theyareusedtopreferentiallyremove strontiumandcesium [21].Theyarevaluableduetotheirionexchangeproperties andtheirabundantpresenceincountrieslikeGreece,Mexico,Iran,andJo rdan[21].Species 24

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ofzeolitesincludeclinoptiloliteandchabazite,theform erbeingthemostabundantlyfoundandhavinghighselectivityforheavymetalion slikelead,cadmium, zinc,andcopper[21].Carbonizedzeolites,createdbycomb ininglyophilic(high a "nityforbeinginadispersionnoteasilyprecipitated)a ndlyophobic(little a "nityforbeinginadispersioneasilyprecipitated)surf acesthatwillbind withorganicandinorganicsubstancesfoundinwastestream s,havebeenused intheremovalofleadfromwastewater[21].A1992studyfoun dthat99%ofa 260ppmleadsolutionwasremovedbycarbonizedzeolites[21 ]. Figure 5.4.3TetrahedralStructureofZeoliteMolecule[7] Removale"ciencyhasbeenreportedtoincreasewhenzeolite saretreatedwith asodium-hydroxide(NaOH)solution.Adsorptionofmetalsi ncreasesasthe temperatureincreases,andincreaseswithadecreaseinpH[ 21]. 5.5IndustrialWaste Figure 5.5.1AdsorptionFreundlichIsothermforGiridihCoal[19] 25

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Industrialwastesuchaswasteslurry,lignin,iron(III)hy droxide,andredmud, haveallbeenexploredasadsorbents.Ligninisaformoflowr ankcoalwhich hascarboxylicacidandphenolichydroxylfunctionalgroup swhichgiveition exchangeproperties.LargedepositsofitexistinAustrali aandIndia[21]. FlyashisawasteofIndianthermalpowerpants,andisoneoft hecheapest adsorbentsthatcanremoveheavymetalssuchascopperions[ 21].Researchinto theadsorptionofmercuryusingyashin1987showedamaximu madsorption capacityof2.82mgof Hg 2+ /g atapHrangeof3.5-4.5[21]. Giridihcoal(GC)hasbeeninvestigatedintheremovalof Cd 2+ ,sorption followingtheFreundlichisotherm(representedinFig5.5. 1,whereloadingis theamountadsorbed)anddecreasingbeyondapHof10assolub lehydroxyl complexesformedatthatpoint[21].Giridihbituminouscoa lhasalsobeen usedforwatertreatment,andpre-treatmentwithnitricaci dhasbeenshown tosignicantlyincreasemercurysorptiontohigherthanac tivatedcarbon.At apHrangeof7-8.5,ithasanadsorptioncapacityof10mgof Hg 2+ /g .Coal andyashhavealsobeenmixedtogetherbyGuptaandcollabor ators,and theynotedthattheadsorptionratewasalmostthreetimesle ssthanactivated carbon,andthatsorptionincreasedwithlowertemperature s,asthesorption processisexothermic(whichmeansthatthechangeinenthal pyisnegative,or thatenergyisreleasedinthereaction)[21].Sawdusthaspr oventobeuseful incopperremoval,reportinganadsorptioncapacityof13.8 0mgof Cu 2+ /g sawdust[21]. 5.6WastePolysterene Fig 5.6.1[72] Plasticsarenotbiodegradable,andincinerationcanbeene rgy-expensiveand alsoreleaseharmfulemissions.Oneofthemostwidelyusedp lastics,polysterene, isanaromaticpolymermadefromthearomaticmonomerstyren e,aliquidhydrocarbonmanufacturedfrompetroleum.Itistheplasticus edinwhiteco!ee cupsthataccountsfor9-10%ofallplasticwaste. Wangetall.wereabletoturnwastepolystereneintoaporous andfunctionalizedadsorbent,showingitspotentialapplicationi nhumicacidremoval. Atypicalhumicacidisformedbythedecompositionofdeadpl antmattersuch aslignin,composedofmanydi!erentcomponents,suchaspic turedinFig5.6.2. Humicacidisubiquitousinsurfacewaterandgroundwateran ditreactswith 26

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chlorineinwatertreatmenttoproducetrihalomethanes,wh icharehumancarcinogens. 5.6.2: HumicAcid[61] Theactiveligandsorfunctionalgroupsofwastepolysteren efunctionasadsorbentsandareimmobilizedonmicroormacrobeads.Theseb eadscanbe preparedwithsyntheticpolymers,polysaccharides,throu ghsuspensionpolymerization,gelation,orchelanation.Itispreferredthat thebeadsusedare porousastheyprovideagreatersurfaceareaforadsorption .Wangetall usedwastepolysterenetocreateaporousandfunctionalize dgranularadsorbenttoremovehumicacid.Theypreparedthegranulesthroug hadissolution/precipitationmethodandthentreatedtheminacontro lledchromicacid processwhichenhancedtheporousstructureandactivatedt hesurface.Finally, porouspolysteryenegranuleswereimmobilizedwithcrosslinkedpolyethylenimine(PEI)tocreateafunctionalizedadsorbent[72]. Bekri-Abbeset.allusedwastepolysterenetocreateaoccu lant-asodium saltofsulfonatedpolystyrene(PSSNa)whichiscompletely charged.Theyadded titaniumoxide,andthenusedthesulfonatingagentsulfuri cacid(96%)H2SO4. Toevaluatethee!ectivenessofthissodiumsaltofsulfonat edpolysterenethey usedturbidwatercreatedbydissolvingclayinthewater.Th ecoagulantused wasaluminumsulfate[53]. 5.7OtherAdsorbents Otheradsorbentsthathavebeenexploredinrecentliteratu reincludeHydrotalcitetype(HT)compounds,whichareaclassofdoublelayeredhydr oxidesthatcan 27

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actasadsorbents.Thepositivelychargedmetalhydroxidel ayersareseparated fromeachotherbyanionsandwatermolecules[51].Hydrotal cites-supported Pd-Cuadsorbentsareabletoremovenitritesfromwaterbase donthereduction propertiesofactivemetals[51]. 6MembraneProcesses Figure 6.1MembraneDiagram[11] Membraneseparationcanbeseenonitsownorasaltrationst agefollowing chlorination.Itcanalsobecombinedwithaocculant/coag ulant,andthe additionofacidforpHcontrol,butisgenerallydonebefore dechlorination. Theadditionofaocculantbeforemembraneseparationisim portantasit helpsconglomeratethecontaminantssothattheycanbemore easilyltered. Thefeedisthewaterthatgoesinandthepermeatesolutionis thesolution thatremainsontheothersideofthelterafterltration(F ig6.1).Thetransmembranepressureisthepressuredi!erencebetweenthelt ratesideofthe membraneandthepermeatesideofthemembrane.Forthemembr aneprocesses tooccur,theappliedtrans-membranepressureofthefeedmu stbegreaterthan theosmoticpressuredi!erencebetweenthefeedandtheperm eatesolutions. Theosmoticpressureisthermodynamicallydenedintermso fthesolventin thesolutionas %$ RT V lna where V w isdenedasthepartialmolarvolume ofthesolvent,Risthegasconstant,Tistheabsolutetemper ature,and A w istheactivityofthesolvent.Fordilutesolutions,theosm oticpressurecanbe writtenas & C s RT ,where C s isthemolarconcentrationofthesolute[33]. 28

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Thetwomembranetransfermechanismsareporeowandsoluti ondi!usion. Whenthemembranetransfermechanismisthroughporeow,pu ricationis heavilydependentonporesize.Whenporesizeissmallenoug hsuchaswith Nanoltration(NF)thepolymersurfacechargemaycausepor eowmembranes toexhibitlowtomoderaterejectionofhighervalentions,a ndlowrejection ofmonovalentions.Asnanoltrationmembraneshavea"loos e"structure,the molecularweightcuto!fororganicsolutesisintherangeof 200-1000Da(daltons -1.66x10 -27 kg )[33]. Solutiondi!usionisthesecondtransfermechanism,wherep enetrantsdissolvemolecularlyinthepolymermatrixofthemembraneandd i !usethrough. Theythendettachfromthepolymatrixontheothersideofthe membrane. Thisisparticularlyapplicableindesalinationbyreverse osmosis.Intransport throughapolymerlm,permeabilityisdenedas: P i = ( PenetrantFlux )( FilmThickness ) ( DrivingForceforTransport ) (3) where P i isthepermeabilityofcomponenti,andthesolute,orsalt,r ejection iscommonlyexpressedintermsof"R"[33]. 6.1MembraneFilters Membraneltersaretheporeowmembranescomposedofthins sheetsthat preventobjectslargerthanporesizefrompassingthrough. Membraneltrationcanbemicroltration(MF),ultraltration(UF),orna noltration(NF). MFandUFremovemicroparticles,macromolecules,inorgani cparticles,organic colloids,anddissolvedorganicmatter(DOM).[20] Theresistanceoftheporemembranes R m ,isdirectlyrelatedtothelength ofthelter z andincreasesbyafactorof r 4 asyoudecreasetheporeradius, r,andcanbedeterminedmathematicallyassuch: R m = 8 z # r 4 $ pore where pore istheporedensityand # isadimensionlesstortuosity factorintroducedbecausetheporeswillnotbeperfectlycy llindrical [14]. A200nmmicrolter(MF)isabletoremovevirtuallyallbacte ria,andlters with100nmporesareusedtoremovecontaminationfrompipin gbetweenthe facilityandend-usepoint.Thefoodandbeverageindustryu sesexclusivelyMF andUFmembranesandMFmembranesareoftenusedinpurifying drinking water. Asapotentialdesalinationtechnique,NFmembranesdonotr ejectasmuch saltasreverseosmosis,butdoprovidemuchhigheruxes,an drequireless inputenergythanROsystemsbecausetheyoperateatlowertr ans-membrane pressures.Theytypicallyrejectabout20-80%ofsodiumchl oridepresent,and ratherthandesalinationareoftenusedto"polish"already cleanwater[33]. 29

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Biofoulingisamainfactorinfailurebymembranelters.Th efoulingcan beeitherreversible,wheresolutesformonthelterlikeag ellayer,orirreversible,wheresolutesplugoradsorbtothepores,whichis referredtoas foulantentrainment.Foulingcontrolcanbedonebyintermi ttentbackwashing, applicationofcriticaluxorTMP,intermittentfunctiono peration,lowTMP, highcrossowvelocity,hydrodynamicshearstressscourin ge!ect,gassparging,increasingtheshearatthemembranesurface,UVradiat ion,andchemical agents.Manyofthesesolutionsproduceonlytemporarye!ec ts.Solutionssuch asNaOCl,NaOH,HCl,and HNO 3 havebeenproventocompletelyrecover membranepermeability,buttheyarealsoharshastocauseme mbranedamage, andchemicalcontaminationintheresultantwater[20]. Solutionstofoulingincludeincreaingthehydrophilicity byeithergratingor coatingwithhydrophillicmoieties,asthenthemembraneon lyinteractswiththe waterlayercoatingit.Coatingthemembraneinhighlyhydro phillicpolymersis typicallyusedbutsincetheyarenonporousthelayerofpoly mermustbevery thin,otherwisethecoatingwillresultinmasstransferlim itations.Another solutionisthechemicalorphoto-inducedgraftingofhydro phyllicchains,which resultsinsmallermasstransferlimitationsthancoating[ 33]. Theperfectlterisdeterminedbythesize,distribution,a ndinterconnectivityofthepores,andthesurfaceandchargeinteractions.Ap erfectlterwould beelectricallyneutral,smooth,hydrophillicandresista nttochlorine[33]. 6.2Osmosis Naturalosmosisoccursasthemovementofwateracrossamemb ranedowna concentrationgradient.Thewaterwilltravelfromthesolu tionoflowersoluteconcentrationtothesolutionofhighersoluteconcent rationtoequalizethe concentration.Thisprocessdoesnotrequireenergyinput. 6.2.1ReverseOsmosis Reverseosmosis(RO)separateswaterbyusingthepressured i !erencetoforce waterontoonesidewhilethesolventremainsontheothersid e.ROisthe standardmethodofdesalinationofseawater.Forthewatert ogoagainstthe concentrationgradientandpassfromanareaofhighsolvent concentrationto anareaoflowsolventconcentration,thepressureappliedm ustbegreaterthan theosmoticpressure. ROrequiresalotofinitialinputenergyinordertocreateth epressure gradient.Theminimumpressurerequiredfordesalinationi sdirectlyrelatedto thesaltconcentrationoftheincomingwater.Inaddition,i tisalsogenerally a !ectedbythepurityofthewater.Thepressurerequiredfor freshwateris approximately15-30kJ/kgoffreshwater,thoughithasbeen reportedthatit canbeashighas61kJ/kg.Theosmoticpressureofseawateris approximately 25bar,andtheosmoticpressurerequiredfordesalinationc anbeanywherefrom 54to80bar[37]. 30

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6.2.2ForwardOsmosis ForwardOsmosisworkssimilarlytonaturallyoccurringosm osisinthatrelieson watertravelingdowntheconcentrationgradient.Solutesa redrawnoutofthe feedsolutionintoasolventofhigherosmoticpressure.Iti sanewerpurication methodfordesalinationthanROandisstillinthedevelopme ntprocess. Itisfavorableoverreverseosmosissinceitdoesnotrequir eenergyinputto createthepressuregradient.Italsohasthepotentialtotr eathighlycontaminatedwaterswithhighsolidscontentandfouling.Forwardo smosisiscurrently muchmoreexpensivethanreverseosmosis,anditispredicte dthatforward osmosiswillnotreplacereverseosmosis[37]. 7IonExchange Ionexchangeisamethodofremovalofinorganicsbypassingt hewatersuccessivelyoverasolidcationexchangerandasolidanionexchan ger,whichreplace theactionsandanionsbyhydrogenionandhydroxideionsoth ateachsaltis replacedbyamoleofwater. 8MagneticallyAssistedProcesses Magneticallyassistedwaterpuricationcanbeintheformo fdirectpurication, seedingandconsecutiveseparationofmagneticocculant, magneticsorbent application,oracombinationoftheaboveprocesses[52]. 8.0.3High-GradientMagneticSeparation(HGMS) SeparationbyHGMSinvolvesanelectromagnetwithmagnetic allysusceptiblewiresinside.Wiresde-homogenizethemagneticeldint hecolumnwhen itisapplied,andproducelargeeldgradientsaroundthewi reswhichattractparamagneticparticlestothesurfaceofthewire.The magneticforce F m = 0 V p M p gradH mustovercometheuiddragforce F d =6 !$b ( v f $ v p ) gravitational F g =( p $ g ) V p g ,inertial,anddi!usionforces.Therearethree typesofmagnetsusedforwaterpurication:permanentmagn ets,whichare preparedfromferromagneticmaterialandaretheweakest,p roducingmagnetic eldsoflessthan1T;electromagnetswhichhaveamaximume ldof2.4T; andsuperconductingmagnets,whichgeneratethehigheste ldof2-10T[52]. 8.0.4MagneticModication Biopolymeradsorbents,whicharealreadye"cientadsorben tsbecauseoftheir highnumberoffunctionalgroups,suchaschitinoralginate canbemodied withmagneticparticles.Thesebiopolymersarereadilyava ilable,low-cost,renewable,bio-degradable,andnon-toxic.Theirmaindownsi deisthattheyare oftenusedinpowderedforms,whichmakethemhardtoseparat eoutfromthe 31

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wateraftertheadsorptionprocessiscomplete,andthiscan causeasignicant pressuredropinthecolumn. Bymodifyingthemsotheyaremagnetictheyaremoreeasilyre moved.Clay isthesameinthatitisdi"culttoseparateoutfromthewater post-purication, andsobymagneticallymodifyingtheparticlesyouareablet operformseparation.Carbonadsorbentshavealsobeenmagnetic-particlemodiedforasimilar reason,becauseinitspowderedformitisdi"culttoseparat efromthewater. Powderedactivatedcarbonhasbeentraditionallydiscarde dwithprocesssludge afterusageinwatertreatment[54]. 9BiologicalandPhysicalMethods Biologicalandphysicalmethodscoversabroadrangeofmeth ods,frombiotechnologytosimplephysicalprocesseslikeboiling.Biotechn ologyinvolvestheuse ofsorbentsandmicrobesforcontaminantdestructionand/o rtransformation. Abiolmongranularactivatedcarbon(GAC)surfacescandeg radedissolved organicmaterialthathasbeenabsorbedontothesurface[52 ]. 9.1Boiling AccordingtotheWildernessMedicalSociety,allpathogens shouldbekilledby thetimeittakeswatertoreachboilingtemperatureof100C ,aswatertemperaturesabove70Ckillallpathogenswithin30minutes,a ndtemperatures above85Ckillallpathogensinjustafewminutes.Recommen dedisthat waterbeboiledfor1minute,especiallyathigheraltitudes wheretheboiling pointofwaterislower[26]. 9.2Evaporation/Distillation Figure 9.2.1SolarDistiller[31] 32

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Figure 9.2.2SolarDistiller[31] Figure 9.2.3AGHSTandSGHT[31] Evaporationandcondensationofthewater,modeledafterou rownwatercycle,islikelyoneofthesafest,energye"cient,andmoste!e ctivemethodsof purifyingwater.Solarstillsdatebacktothe16thcentury[ 31].Thebasicprincipleofasolardistilleristhattheenergyfromthesunheat sthewatertothe 33

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pointofevaporation,andthentheevaporationrisestocond enseontheglace surfaceofthedistiller,whereitcondensesandthenisdeli vereddownthesides ofthedistiller.Unlikemanyothermethods,itcanbeusedto desalinatewater. Themajordrawbackthatlimitsitsuseisthesmalloutputofs olardistillers, whichcanvarydependingonthesun'sposition,weathercond itions,design, operationaltechniques.waterdepth,blackdye,andwinde! ects[31]. TwotypesofsolardistillersareAssymetricGreenhouseTyp e(ASGHT)or singleslope,whichinvolveonesheetofglassslantedupwar dsandSymmetric GreenhouseType(SGHT)ordoubleslopewhichinvolvetwoshe etsofglass thatmeetinthemiddletoformsimpletriangularroofshapef romthefront [31](Fig.9.2.3).ThesingleslopeAGHSTmaygivebetterres ultsthandouble slopeSGHTforcoldclimaticconditions,whereassummercli maticconditions maygivebetterresultsfordoubleslopeSGHT[18]. Performancecanbeincreasedbyusingblackdye,usingadeep basin,and increasingthedi!erenceintemperaturebetweenthebasin( heatsource)and theglasscover(heatsink).Usingthesetechniques,inEgyp t,theoutputstill variedbetween.5and5.0 kg m 2 [18]. 9.3SoilBiotechnology(SBT) Soilisanaturallterforwaste,asmostorganicmatterisea silydegradedbysoil andthemicroorganismsinit.Soilbiotechnologyistheuseo faformulatedsoil environmentwherebioconversionisbroughtaboutbyphotos ynthesis,mineral weathering,respirationandothernaturalevents.Themedi umisformulatedto therightmineralconstitution,andtheculturecontainsth emicrooralgeophaguswormPhertimaelongataaswellassocalledbio-indicato rplants[52]. ThebulrushplantScirpuslacustriscanocculatewatersin aslittleasa day[17],andtherootsoftheplantsareabletometabolizepo llutants.Other plantswhichhaveahighuptakeoforganicmatterincludeTyp haangustifolia andAncoruscalamus[17]. Waterhyacinth,originallyfoundinJamaica,isaplantthat isverygoodat removinginorganicandorganicpollutantsfromwastewater [17],butapplication ofwaterhyacinthintropicaldevelopingcountriestoclean upwastewaterhas beenmetwithseriouscriticism.IthasimpairedshinginSu danandEgypt, providesagoodbreedinghabitatformosquitoeswhichcarry diseaseslikedengue andmalaria,andtherearereportsthatthehostsforfreshwa tersnailsBulinus andBiomphelariacarryingdangerouspathogenshavebeenfo undattachedto theirroots[41].InIndia,problemsarosestartinginthe19 60'swhenscientists fromthePublicHealthEngineeringUnitoftheAllIndiaInst ituteofHygiene andPublicHealthinCalcuttalookedforawaytodisposeofth ewaterhyacinth plantswithouthavingthemleachthepollutantstheyhadads orbedbackinto thewatersource[17].Otherplantsusedforwaterpuricati onhavebeenfound tohaveannegativeimpactonmicroorganisms,suchasMentha aquatica,Alisma plantago,andIrispseudacorus,allwithbactericideroots ecretions. 34

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9.4SandFilters Therearemanydi!erenttypeofsandlters,andtheycanallb emodiedwith metaloxideorhydroxidecoatingstoincreaseadsorbency. 9.4.1RapidGravitySandFilters Arapidgravitysandlterneedsocculantchemicalstooper ate.Aperfect rapidgravitysandltersupportstheltermediumandgrave l,collectsltered waterevenlyfromthebottomofthelter,anddistributesai randwatervenly acrossthebottomofthelterduringbackwashing,whichisn ecessarytoremove thesolidscollectedinthelter.Thelterooristhusvery importantandcan beofthreetypes:theheaderandlateraltypeunderdrain,wh erebackwash entersthelterbottomthroughthepressurizedume(heade r);theplenum oortype;andthetwopasslateraldesign.Thedualparallel lateralunderdrain isthebest,asitistheeasiesttoinstall,hasgooddistribu tion,acompactlter design,hasgravelsupportlayersthatpreventneltermed iumfromentering theunderdrainandblockingit,andisoverallsaferthanthe othermethods. Insteadofaneltermediumyoucouldalsouseamediaretent ionplatemade ofhighdensitypolyethylenewhichwouldhave1/10thethick nessofthegravel supportlayer[55]. 9.4.2RapidPressureSandFilter Therapidpressuresandlteralsoneedsocculantchemical stooperate.Using externallycreatedpressure,itisabletooperateatafastr atesimilartothe rapidgravitysandlter. 9.4.3SlowSandFilter Fig DiagramofaSlowSandFilter9.4.3.1[36] 35

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Aslowsandlterisatypeoflterthatusesgravityratherth anpressureto operate,andatraditionalslowsandlterisessentiallyan open-toppedbox(usuallymadeofconcrete),drainedatthebottom,andpartlyll edwithaltering medium(cleansand).Theslowsandlteristheonlysandlte rwhichdoesnot needchemicalaids,andisfrequentlyusedindevelopingcou ntries.Becauseno additionalpressureisapplieditsoutputismuchslowertha ntherapidpressure sandlter[36].Aslowsandltercanrunforweeksormonthsw ithoutcleaning.Thewaterpassingthroughtheltergenerallyliesbetw een.1and 4 m 3 /h persquaremeterofsurface.Anesandmustbeused(0.62.0mm particle size)sothatresistanceisincreased,otherwiseitisarapi dsandlter,which requirescleaningmuchmoreoften.Toclean,thesandcaneit herbereplaced orbackwashingcantakeplace,inwhichhighpressurewateri sforcedupwards throughthewholebedandcompressedairisusedtoscourthei ndividualgrains. Thewaterlevelinthelterboxshouldnotdropbelowthesurf aceofthelter mediumduringoperation,whichiswhyaWeirisincorporated intheoutlet pipesystem,soitmaintainsminimumwaterdepthandaerates theoutgoing water.Theschmutzdeckeismadeofthreadlikealgaeandnume rousotherforms oflife,includingplankton,diatoms,protozoa,andbacter ia,anditisthelter skinwhichthewatermustpassthrough.Cleanquartzsand,du etoitscrystallinestructure,hasanegativechargeandsoitisabletoa ttractpositively chargedcolloidalmatter(crystalsofcarbonates,occuli ofironandaluminum hydroxide),aswellascationsofiron,manganese,aluminum ,andothermetals. Areversalofchargehappensthroughoutthelifetimeofthe lter.Typically,a slowsandlterhasrawwaterthatliesforseveralhoursonav erageinthespace abovethemedium,duringwhichtimethereissomeseparation andsettlement ofthelargerparticles,andthenitpercolatesforatleast2 hoursthroughthe sand. 10DirectChemicalMethods Thee!ectivenessofallchemicaltreatmentisrelatedtofac torssuchastemperature,pHlevel,andthebrackish(salinity)levelofthewat er.Toensurethe e !ectivenessofchemicalmethods,largeparticlesmustbes trained,otherwise themethodmaynotpenetratecompletely. 10.1Chlorine Chlorineisusedtopurifywaterandkillbacteria.Whenitis addedtowater, itquicklyhydrolyzes: Cl 2 + H 2 O H + + Cl + HOCl (4) Theequilibriumconstantforthereaction, K c ,is K c = $ [ H + ][ Cl ][ HOCl ] / [ Cl 2 ] (5) 36

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Oneoftheproductsofthereaction,hypochlorousacid(HOCl )isaweak acidthatdissociates: HOCl "# H + + OCl Withanionizationconstantof 2 7 x 10 8 [42]. HOCl and OCl areknownasfreeavailablechlorine,andifammoniais presentthenmonochloramine,dichloramineandtrichloram inewillbeformed, whichareknownasthecombinedavailablechlorine[42]: NH + 4 + HOCl NH 2 Cl ( monochloramine )+ H 2 O NH 2 Cl + HOCl NHCl 2 ( dichloramine )+ H 2 O NHCl 2 + HOCl NCl 3 ( trichloramine )+ H 2 O Whilecombinedavailablechlorineislesse!ectivethanfre eavailablechlorine,itismoreeasilyretainedasadisinfectantinawaterd istributionsystem. Becauseexcessammoniaisnotdesired,atlevelsof20mg/Lof NH 3 N ina waterwithapHbetween5.0and8.0,chlorinationwithatleas t8:1weightratio ofClto NH 3 N producesdenitricationthatremovespollutantammoniafr om thewater[42]: NH + 4 + HOCl NH 2 Cl + H 2 O + H + 2 NH 2 Cl + HOCl N 2 ( g )+3 H + +3 Cl + H 2 O Thebreakpointofchlorineisthepointatwhichdisinfectio nisensured,and thisoccurswhensomeHOCLand OCL donotreacttoformproducts,and asmallamountof NCl 3 forms.Thishappenswhenthereisasu"cientlyhigh Cl:Nmolarratioinwatercontainingammonia[42]. Chlorineisfrequentlyusedindisinfectionsystemsduetoi tse!ectivenessin disinfection.Therearealsoconcernsaboutitse!ectsonhu mans.Morethan 600disinfection-by-products(DBP's)havebeenidentied ,whichcanformwhen Chlorinereactswithdissolvednaturalorganicmatter(DNO M)[42],including trihalomethanesandhaloaceticacids.Chloroformisoneof thetrihalomethanes thatcanbepresentinthewaterafterpuricationinthepres enceofhumicmaterialsarepuriedwithchlorine[42].Humicacidsareprod ucedbydecaying organicmatterandcanbefoundindystrophiclakes,soil,an doceanwater. Thus,generally,chlorinatedwatermustrstbedechlorina tedbeforeitcanbecomepotable.Inthedevelopingworld,calciumhypochlorit e(bleachingpowder) whichcontainsapproximately30%availablechlorineisoft enused. 37

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10.2ChlorineDioxide ClO 2 isanalternativethatunlikeChlorine,doesnotproduceimp uritytrihalomethanesinwatertreatment,buttherearemultipledra wbacks.Itdoes notchlorinateoroxidizenitrogen-containingcompounds, andtheremaybe healthconcernswithitsdegradationbyproducts, ClO 2 and ClO 3 [42].Chlorinedioxideworksinacidicwaterby ClO 2 actingasanoxidantinthefollowing halfreaction[42]: ClO 2 +4 H + +5 e "# Cl +2 H 2 O Inneutralwater,chlorinedioxideislargelyunreactantun tilitcontactsa reducingagentwithwhichitreactswith.However,itcanals oactsasanoxidant inthehalfreaction[42]: ClO 2 + e "# ClO Becauseitisahighlyreactivegaswithorganicmatterandli ght,itisnot shipped,andisgeneratedatthesiteofdisinfection,possi blybythefollowing mechanism[42]: 2 NaClO 2 ( s )+ Cl 2 ( g ) "# 2 ClO 2 ( g )+2 NaCl ( s ) Elementalchlorineisoftenaddedtopreventunwantedreact ionswith Cl 2 gas. 10.3Iodine Iodineismoree!ectivethanchlorinebasedtreatmentsinin activatingGiardia cysts.However,itisusedlessfrequentlytochlorineassom epeopleareallergic, anditisnotrecommendedtobeusedonpersonswiththyroidpr oblemsor pregnantwomen[30]. Abedoftinyresinbeadsofiodineionsisused,however,tore cyclewater ontheInternationalSpaceStation(ISS).Thismodelwaslat erusedbythe nonprotNGO"ConcernforKids"toprovidesustainabledrin kingwaterto animpoverishedareainIraq.Thismodelissimpleandrenewa ble,purifying approximately5gallonsperminutewithoutrequiringelect ricity,makingitideal fordevelopingcountries.Thebedofiodineionsonlyneedst oberechargedso thatitcontinuestowork. 11CatalyticProcesses Catalytictechnologiesareacombinationofoxidation,irr adiation,electronand catalysisasameansofgenerationhydroxylradicals,super oxideradicals,and 38

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hydroperoxylHO2radicalsatstandardtemperaturesandpre ssure.Theoxidativeprocessescanenhancemineralizatione"ciency,wh erethenalproductsofdegradationreactionsarecarbondioxide,short-ch ainorganicacids,and inorganicions,whicharealllesstoxicandamenabletobiod egration[40].Catalyticprocessesincludeoxidationorreductionofpolluta nts,solarassistedoxidation,photo-assistedoxidation,heterogeneouscatalytic ozonation,electrocatalysis,electro-FentonMethods,photo-electricprocess,an dphoto-electro-Fenton processapplications[52].Magneticmetaloxidecomposite canalsobeusedfor catalyticoxidation. 11.1Oxidation Oxidationasageneraltermmeansalossofelectrons,oranin creaseinthe oxidationnumberofthemolecule,atom,orion.Oxidationde gradespollutants eitherthroughdirectoxidation,whichinvolvesinteracti onsbetweenpollutants andanodes,andmediateoxidation,whichinvolvesreaction sbetweenpollutants andoxidants.Hydroxylradicals,ozone,hydrogenperoxide ,andhypochlorite areformedbyelectrodereactioninelectrocatalyticoxida tion[40]. Catalyticoxidationbymagneticmetaloxidecompositesupp ortadsorbents suchasthepowdered CuFe 2 O 4 and MnO Fe 2 O 3 whichcanbeformedby asimpleco-precipitationmethodfromenvironmentallyfri endlyandlowcost materials.Theycanberecoveredeasilyusingmagneticsepa rationtechnology,whichovercomesthedisadvantagesofseparationdi"cu ltyofpowdered adsorbents[51]. MnO 2 hasalowoxidationpotentialandisane!ectiveoxidizingag entof arsenite.Manganese-dioxidebasedadsorbentscanbeusedt oremovearsenic byrstoxidizingit,buttheadsorptioncapacityislowands oitsapplications arelimited.Toimproveremovale"ciency,compositeadsorb entscontaining MnO 2 havebeensynthesizedsuchasMDCS(manganesedioxide-coat edsand) whichhasgoodremovalperformance.Fe-Mnbinaryoxideadso rbente!ectively oxidizearseniteandadsorbtheproducedarsenatesimultan eously[51]. 11.2Solar-assistedOxidation Solarassistedoxidationisrecommendedincountrieswhich havealotofsunlightbutitse!ectivenessisalsorelatedtotheturbidityo fthewater,asturbid waterswilllimitlightpenetration.Otherconstraintsare wateroxygenation, theexposuretime,andthedepthofthewater.Unfortunately forthismethod, themajorityoftheUVlightthatwouldpurifythewaterisabs orbedbyour atmosphere,andtheUVlightwhichreachesthesurfaceisres trictedbetween thewavelengthrangeof295and400nm.Onewell-knownmethod employed indevelopingcountriesiscalledSODIS,whichusestranspa rentpolyethylene terephthalate(PET)bottles,sometimespaintedblackonon eside,andlled withanaeratedsourcewaterandexposedtoenergy,andhasad iarrhealdisease reductionrateofapproximately31%[44]. 39

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Apotentialforsmallquantitesofhand-drawndrinkingwate risSOLAIR, whichisadisinfectionprocessthatwascitedbyV.Meyeret. allwhichvirtually eliminatesdisease-causingbacteriawithin7hours.Itinv olvesleavingasealed containerpartiallylledwithwaterinthesunandshakingi tvigorouslyonce everyhour,whichnotonlyaeratesthewaterbutalsomixesit sothatthelight isabletoreachallpartsofthewaterratherthanbelimitedt oitspenetration capabilities.InV.Meyer'sexperiment,thebottlesusedto purifythewater were25L,lledupto20L[58]. 11.3Photo-assistedOxidation 11.3.1 TiO 2 Photocatalyticdegradationby TiO 2 iswidelyusedtoremovetoxicchemicals. TiO 2 isoftensupportedbytheuseofadsorbentstoremoveorganic molecules duetothelimitationsinusingbare TiO 2 inphotocatalyticreactions.Asasmall molecule,itaggregatesveryquicklyinasuspension,causi ngittoloseitssurface areaandthuscatalytice"ciency.Especiallywithnon-pola rorganiccompounds, itisapooradsorbentduetoitspolarsurface.Scientistsha veexperimentingwith immobilizing TiO 2 onporousadsorbentmaterialslikesilica,activatedcarbo n, alumina,clay,andzeolitestoproducecompositeadsorbent /catalysts.Using TiO 2 photocatalyst,arsenitecanbequicklyoxidizedtoarnenat e,asarsenite removalisnotase!ectiveasarsenateremoval.Onceoxidize d,arsenatecanbe removedusingUVlighttoproduceoxidants.Thelowadsorpti oncapacityand theseparationproblemofpowdered TiO 2 ,however,haslimiteditsapplications incontaminatedwater[51]. 11.4Ozonation Figure 11.4.1OzoneMolecule[62] Ozone( O 3 )issometimesusedinplaceofchlorine.Waterisltered,co oled,dried andpressurized,andthenanelectricdischargeisappliedo faround20,000Vto producetheozone[42].Theozonecontactsthewaterfor10-1 5minutesafter beingpumpedintothecontactchamber[42].Ozoneismoree!e ctiveatkilling 40

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virusesthanchlorine,butthelowsolubilityofozonelimit sdisinfectionpower [42].Alsolimitingdisinfectionpoweristhatozonedecomp osesspontaneously inwater[42]: 2 O 3 3 O 2 Therateofdecompositionofozoneinwateris: d [ O 3 ] /dt = k 0 [ OH ] 0 55 [ O 3 ] 2 Forthisreason,chlorineisoftenaddedtotheozonationpro cesstoensure disinfection[42]. 11.4.1HeterogeneousCatalyticOzonation HeterogeneousCatalyticOzonationwasdevelopedtooverco methelimitations ofozonationprocessessuchastheformationofbyproducts, andselectivereactionsofozone,whicharedesignedtoenhancetheproduction ofradicals(OH). Ithasapotentiallyhighere!ectivenessinthedegradation andmineralizationof refractoryorganicpollutants,withoutthedangerousbypr oductsofothermethods.Itsadvantageoverhomogeneouscatalyticozonationis thatitistheease ofcatalyticretrievalfromreactionmedia. Co-basedcatalystssuchas Co/SiO 2 CoOx/Al 2 O 2 havebeenusedinozone decompositionstudies.Thehighoxidationactivityinthep resenceofozoneis explainedbythehighcontentofmobileoxygen,whichdepend shighlyonthe preparationmethodused[40]. 11.5Electrocatalysis Electrocatalyticoxidationhastheadvantagethatthereis asmallreactorsize sonotmuchlandareaneedstobeallocatedandthereactorsar erelativelyeasy tohandle.Catalysisthroughelectroxidationishelpedbyt hemodicationof certainoxides( PbO 2 MnO 2 ) onthesurfacesoftheelectrode. ElectrocatalysiscanremoveBPA,whichistheharmfulchemi calfoundin manyplastics.VariouselectrodeslikeTiandPtmesh,and Pt/Ti ontheirown arenotabletodegradeBPA,duetoelectrodedeactivation., andpoorgeneration ofmorehydroxylradicals.CombinedwithCatalysis,theyar eableto.Another possibilityforelectrocatalysisis SnO 2 /Ti andcarbonberelectrodes[40]. 11.6Electro-FentonMethods Electro-Fentonprocessesareconsideredmoree"cientelec trochemicalmethods forwaterpurication,andtheyinvolveusingelectrogener ationofstrongoxidants. 41

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11.7Photo-electricProcess Photo-electricprocessesareadvancedoxidationprocesse sthatcouplelowenergy UVwithsemiconductorswhichactasphotocatalysts.TheUVl ightcaneither befromalampimmersedwithinthereactororfromoneoutside thereactor inwhichthelightisdistributedfromthesourcebywayofre ectorsoroptical bers[16]. Theadvantagesofthephotocatalyticprocessarethecomple tebreakdownof organicpollutantstoyieldCarbonDioxide,Water,andmine ralacids.Thereactionsarepromotedbysolidphotocatalystparticleswhic hareeitherdispersed intheliquidorimmobilizedonthesurface.Sincephotocata lyststhataredispersedintheliquidrequirelaterseparation,theyaremore oftenimmobilizedon asurface.However,immobilizationofthesemiconductorso nthesupportgenerateauniqueprobleminthattheinterfacialsurfaceareao fthephotocatalyst mayleadtoamasstransferlimitationproblem[16]. Limitationsofthephotocatalyticprocessesarethedeptho fpenetration ofUVlight,whichislimitedbystrongadsorptionsbycataly stparticlesand dissolvedorganicmolecules.Scientistshavetriedtosolv ethisproblembyusing glassbeadsandberglassmesh,whichincreasethesurfacea reaavailablefor thecatalyst,butnotthephotocatalystsurfaceareaasnota llofthelightmay reachthephotocatalyst[16]. Photoelectriccatalyticmethodsinvolvethehetereogeneo usphotocatalysis usingsemiconductoroxidessuchas TiO 2 andhavebeenshowntobee!ectivein treatingwater.Theadvantageofphotoelectrocatalyticme thodsisthesimplicity ofconstructingandmanagingthereactor.Theapplicationi satthelargescale, andthemainlimitationiselectrodematerialsthathavespe cicmaterialsto beusedinphotoelectriccatalyticmethods. Ti/PbO 2 ,Ti/SnO 2 ,Ti/IrO 2 ,and glassycarbonaregenerallyused[40]. 12LocalMethods 12.1SouthAmerica InChile,thereishistoricalreferenceinthe19thcenturyo fuseofthesapfrom theunacactusOptuniacusindicatoclarifythewater[17]. InPeru,textsfrom the16thand17thcenturyshowthatpitu,apowderthatismade fromroasted grainsofZeamays,wasusedbysailorstopurifythewater. 12.2Asia 12.2.1India Writteninthe1stcenturyADbythesageSushrata,thetreati seSushrata Samhitacontainoutlinessevenmodesofpurifyingwatertha tincludeusingthe naturalcoagulantkatakaseeds(Strychnospotatorum),and disinfectionbyheat 42

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[17].SushrataSamhitacontainrecommendsdisinfectionby heatbyexposing watertothesun,orbyimmersingred-hotironorhotsandinit [17]. Inmorerecentyears,othernaturalocculantshavebeenuse dinIndia,such astheseedsofSemecarpusanacardiumandPongamiaglabra[1 7].IntheTamil Naduvillages,Strychnospotatorumisrubbedagainstthebo ttomofanearthen jarbeforeitislledwithwater.InpartsofIndia,muddywat erismixedwith woodashfromthesal-tree(Shorearobusta)andthenltered throughacloth [17].BuddhistsandJahnscovertheirwatervesselswithlin ensothatitactsas alterwhenpoured[17]. InsouthernKerala,rootsfromtheVetiveriazizanoidespla ntareplacedin aclayjarwithholesinthebottomandwaterislteredthroug h.Innorthern Kerala,lotusplants(Nelumbiumsp.)areplantedinwaterso urces[17],withthe thoughtthatrootsareabletoclarifythewater.AlsoinKerl aa,burntcoconut shellsaresometimesthrownintothewatertopurifypollute dwater[17].In southernIndia,acoagulantmadefromElettariacardamomum isdustedover thewater[17]. 12.2.2Iran TheGreekauthorHerodotusreportedthatPersiankingswoul dboiltheirdrinkingwaterandthenstoreitinsilverjars[17].InSouthweste rnIran,wateris lteredthroughthebottomoflargeearthenjars[17]. 12.2.3Indonesia OnBali,aJempengstonelter(SarainganbatuJempeng)made fromaporous stonecalledadasisusedtoltermuddywatergatheredfromi rrigationcanals [17].Theaverageheightofthislteris60cm;averagediame ter50cm;and averagethicknessofthewalls10-12cm[17].Thewaterpasse sthroughthe canalsandcirculatesthroughthelters[17]. 12.3Africa 12.3.1Egypt TheGreekauthorGalenoswroteabouthowtheancientEgyptia nswouldpurify waterusingearthenwarejars[17].IntheareaoftheNile,th e16thcentury ItalianbotanistProsperoAlpinonotedthattheEgyptianss mearedtheedges ofthewaterjarswithsweetalmonds[17].Inthe19thcentury ,theGerman zoologistadditionallynotedthatinadditiontowater,the Egyptiansalongthe nileusedalumandbroadbeanstoclarifythewater[17]. 12.3.2Sudan InSudan,groundnuts(Arachishypogaea)wereusedasasimil arocculant[17]. AlsoinSudan,localsdigfromtheNiletoobtainatypeofclay soil,called 43

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rauwaq,orclarifyingsoil[17].Waterislteredthrougha thinclothofwomen's clothingtoremoveplantdebris[17]. SudanArabwomenarecreditedwithdiscoveringMoringaOlei fera,andsome womenplacethepowderedseedsinateabag(asmallbagofclea nclothwith astringattached)andsteepitinthewater[17].Innorthern Sudan,amethod usedbythewealthypopulationofWadiHalfausesEgyptianbu rntclayuinauwi ZirsjarsmadeinQena,upperEgypt,lterswaterthroughthe jarsintoasmaller clayvesselunderneath[17]. InDongola,northernSudan,alumisusedwithseedsofthehyp oestesverticillarisplantasmixtureofcoagulantstopurifythewater. Innorthernand westernSudan,palmfansfromtheplantsPhoenixdactylifer aorBorassus aethiopiumareinstalledintemporarywaterbasinsasmecha nicallters[17]. InKologi,coveredclaypots,sealedwithclay,areusedtost orewater[17].In centralSudan,duringtheoodseasonwaterisstoredfor1-2 daysinclayjars sothatsuspendedmattersettlesdown,andthismethodisals ousedasaform ofpre-treatmentduringnon-oodseason[17].Incentralan dnorthernSudan, ifnocoagulantsareavailable,muddywaterissettledbyspr eadingalayerof doughorcurdsonthewater[17].InwesternSudan,muddywate ristreated withtheleavesandtwigsfromtheBosciasenegalensistree[ 17]. InsouthernDarfur,coagulantmadefromthedustfromtermit ehillsisdusted overthewater[17].ThemostcommonuseofcoagulantsinSuda nistoprepare eitherclarifyingclaysoilorpowderedplantmaterialsbya ddingasmallamount ofwaterforandstirringfor10-20minutes[17].Thesuspens ionisthenpoured overthewaterandthesuspendedmattersettlesdown,andcla ricationtakes atleastonehour[17].IncentralSudan,waterisfetchedatw aterholeswhere theplantsCyperussp.andTyphaangustatagrow,bothwhicha replantswhich clarifythewater. 12.3.3Mali InMali,villagersoftheBamakoareauseawinnowingsieveto lterwaterfrom openwellswhenithasalotofdustordryleavesinit[17].Als ointheBamako area,whenananimalhasdiedinawatersource,thevillagers throwalloftheir ashesfromcookingintothewater,andthencoveritwithamat .Theywaita weekbeforedrinkingfromitagain[17].Awinnowingsieveis alsousedbythe HausasandDjermatolteroutmudfromwatergatheredfromth eNigerriver [17]. 12.3.4Nigeria InNsukka,locatedineasternNigeria,waterfromtherainys easonisstored half-buriedinthegroundfor5monthsinclaypots,withacap acityof50liters each.About50claypotsareusedper20personhousehold,and thewateris puriedusingsedimentation[17]. 44

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12.3.5Niger TheTuaregoftheAyrmountainsclarifywaterwithbonesused fromthelegs ofsheeporgoatswhichhavebeenroastedinashes[17]. 12.3.6Kenya IntheTanaRiverDistrict,thePokomoclarifydrinkingwate rbytwirlingthe nakedbranchesoftheMaeruasubcordatatreetocoagulateth ewater[17]. 45

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PartIV MethodsofCharacterization Thecharacterizationofwaterishighlydependentonwhatyo uaretryingto detect,aseachtestisdi!erentanditistoomoney,energyan dtime-expensiveto testforallthings,whichiswhyindicatorsareused.Within microbialpathogens, certainmicroorganismsareusedasindicatorsforthequali tyofthewater,such asE.coli. Theimportantfactorsforindicatororganismsare[45]: Presentwheneverpathogensarepresent Presentinthesameorhighernumbersthanpathogens Specicforfaecalorsewagepollution atleastasresistantaspathogenstowatertreatmentanddi sinfectionprocesses preferablynonpathogenicanddetectablebysimple,rapid ,andinexpensive methods Foreachtest,theidealdetectionwouldberapid,sensitive ,accurate,inexpensive,andeasytoperform. Guidelinesformethodsonaninternationallevelcanbefoun dfromtheInternationalStandardizationOrganization(ISO)[45].Gui delinesformethods canbefoundintheAmericanStandardMethodsfortheExamina tionofWater andWastewaterorinthetechnicalreportsfromtheUSEnviro nmentalProtectionAgency(EPA).Characterizingbacteriacanbedi"culta stheycanenter dormantstateswheretheyareviablebutnotculturable. 13Bacteria 13.1EscherichiacoliandTotalColiforms Whileacountoftotalbacterialcoliformsisusedasanindic atorofwaterquality, manycoliformsarenotpathogenic.ThepresenceofE.coliis oneofthemost indicativeoffaecalcontamination,butnotallstrandsofE .coliarepathogenic either.Thepresenceoftotalcoliformsmaybecompletelyha rmless,astheycan originateinorganicvegetablematter[32].Theabsenceofc oliformsalsodoes notmeanthatthereisnodangerindrinkingthewater,asprot ozoancyststend tobemoreresilienttowaterpuricationthancoliformbact eria[32]. IntheEPA-approvedmethodofsimultaneousdetection,100m Lofwater islteredthrough47-mm,.45-micrometerporesizecellulo seestermembrane lter[12].Thebacteriaiskeptonthelterandthenthetle risplacedona 5-mLplateofMIAgarorapadsaturatedwith2-3mLofMIbroth. Twoenzymesubstrates,theuorogen4-Methylumbelliferyl-Beta -D-galactopyranoside 46

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(MUGal)andachromogenIndoxyl-beta-D-glucuronide(IBDG )areincludedin themediumtodetecttheenzymesbeta-galactosidaseandbet a-glucuronidase, producedbyTCandE.Colirespectively.Thentheplateisinc ubatedfor24 hoursat 35 o C .Afterincubation,allcoloniesarecountedinnormallight .Total Coliforms(TC)produceuorescentcoloniesuponexposuret olongwaveultravioletlight(366nm)afterprimaryculturingonMIagarorbr oth.Fluorescent coloniescanbeblue-white(TCotherthanEColi)orblue-gre en(Ecoli)or ourescenthalosmaybeobservedaroundtheedgesoftheblue -greenE.coli colonies[12].ThetestrecommendedbytheISO,theMostProb ableNumber (MPN)testisdonebyinnoculatingseveralsamplesofamediu mbythewater. 14Protozoa 14.1CryptosporidiumandGiardia EPA'srstdraftforprotozoandetectionwaswrittenin1996 ,Method1622,and itwassolelyforCryptosporidiumdetection,andwasnotna lizedasamethod untilJanuary1999.Anacceptableimmunomagneticseparati onsystemforGiardiawasidentiedinlate1998,andamethodforsimultaneo usdetectionof thetwoprotozoawasvalidatedinearly1999.Thisnewmethod ofsimultaneous detectionwasgiventhename1623,andhassincebeenupdated asrecentlyas 2005[13]. Themethodusesconcentration,immunomagneticseparation (IMS),and immunouorescenceassay(FA)microscopy.Itrstrequires theltrationof thewatersothatoocysts,cysts,andextraneousmaterialsa reretained.Then thematerialsonthelterareelutedandtheelutateiscentr ifugedsothatthe oocystsarepelleted,andthesupernatantuidisaspirated .Theoocystsand thecystsaremagnetizedbyattachmentofmagneticbeadscon jugatedtoantiCryptosporidiumandanti-Giardiaantibodies.Themagntiz edoocystsandcysts arethenseparatedfromtheothermaterialsonthelterusin gamagnet.Then, themagneticbeadcomplexisseparatedfromthecystsandooc ysts[13]. Finally,toenumeratethecystsandoocysts,theyarestaine donslideswith uorescentlylabeledmonoclonalantibodiesand4',6-diam idino-2-phenylindole (DAPI).Thesampleisexaminedusinguorescneceanddi!ere ntialinterference constrast(DIC)microscopy. Thecystsarethenidentiedbyvisuallyscanningtheslidef orobjectsmatchingthesize,shape,anduorescencecharacteristics,andt henumberofconrmedmatchesarecounted.Theourescencecharacteristic sofCryptosporidiumoocystsisthattheyexhibitbrilliantgreenuorescenc eunderUVlight, whichmeanstheyareFA-postiive.Theyarealsotypicallyar ound 4 $ 6 m ,and areroundoroval[13]. GiardiacystsalsoexhibitbrightgreenuorescenceunderU Vlight,(meaning theyareFA-positive),theyaretypically8-18 # mlongand5-15 # mwideand theyareovaltoround.EPAhasonlyvalidatedtheuseoflabor atoryltration ofbulkwaterbuteldltrationcanalsobeused. 47

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15Viruses Virusesarepoorindicatorsystemsbecausethetestsare10100xmoreexpensive thancoliformtests,theyrequiresophisticatedlaborator iesandskilledexpertise, andresultstake1-4weekstocomeout(GrabowandNupen,1981 ;IAWPRC StudyGrouponWaterVirology).Inaddition,theneedtoproc esslargevolumesofwaterfortherecoveryofsmallnumbersofvirusesisi nconvenientand increasestheriskofsamplecontamination(Grabow,etal., 1984b);andtheefciencyofadsorptionelutionmethodsusedfortherecovery ofthevirusesfrom waterrarelyexceeds50%forsomevirusesandislowerforoth ers(Grabowet al,1984).Furthermore,thenumbers,behavior,andresista nceofthedetectable "indicator"virusesmaydi!erextensivelyfromthoseofinf ectiousvirusescommonlytransmittedbywater(Grabow,1986b)[45]. Virusesareverydi"culttodetectinwaterandtheoriginala ttemptsused cellculturesonplaquescollectedbymicrolters,usingla rgevolumesofwater [71].Ittakesseveralweekstodetectthevirusesusingplaq ueassayorobservationofcytopathice!ectsduetohowslowlytheypropagate onspeciccell lines[71].Traditionalvirusproceduresusebeefextractt oelutevirusesfrom ltersandacidorpolyethyleneglycol(PEG)toprecipitate thevirusesfrom ltereluates[71].Someentericviruses,suchasNorwalkvi rus,rotaviruses,and hepatitisAvirus(HAV)arenearlyimpossibletocultivateb ycellculture[71]. Enzyme-linkedimmunosorbentassay,radioimmunoassay,ra dioimmunofocusassay,andnucleichydridizationareallusedtoassistindete ctionincellculture ofvirusesinsewageorshellshsamples[71]. Inthepasttwodecades,anewtechnologyhasbeenincreasing usedcalled reversetranscriptase-polymerasechainreaction(RT-PCR )formorerapiddetectionofenteroviruses,poliovirus,rotavirus,andNorw alkvirus[71]. 15.1Coliphages ColiphagesareatypeofvirusthatinfecttheE.colibacteri a[45].Theymeetthe mostindicatorsforvirusesbecausesomeofthemresemblehu manvirusesinsize, morphology,andstructure,andtheyareatleastasresistan ttowatertreatment anddisinfectionprocesses,theynormallyoutnumberother pathogens. 48

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16Inorganics 16.1SpectroscopicMethods Figure 16.1.1Absorption,Emission,andFluorescence[24] Spectroscopicmethodsofanalysisusethecharacteristics oflighttodetermine thecharacteristicsofthesample.Lightistransmittedinp acketswhichhave bothparticleandwaveproperties.Theenergy(E,measuredi nJoules)ofthese packetsisdeterminedby: E = hf WherehisPlanck'sconstant( 6 62 x 10 34 Js ),andfisthefrequency.The frequencyofthelightisrelatedtothewavelength $ bythespeedoflightcwhich isconstantinavacuum: f = c/% Theelectromagneticspectrum(Fig16.1.2)isacontinuouss pectrumofvaryingwavelengths,onlyaverysmallsectionofwhichisinthev isibleregion. 49

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Fig 16.1.2TheElectromagneticSpectrum[24] Accordingtoquantumtheory,atoms,moleculesandelectron sexistincertain denitequantumenergystates,andhaveagroundenergystat e,butcantransitiontohigherorlowerenergystates.Whenatomstransiti ontolowerenergy statestheyreleaseenergyinawavelengththatischaracter istictothatatom, andsospectroscopicmethodscanbeusedtocharacterizethe elementbasedon thewavelengthreleased.Theseenergytransitionsinatoms canbeinelectronic ( E e ),rotational( E r ),andvibrational( E v )energylevels.Thetotalenergyof theatomisacombinationofalloftheseenergies: E = E e + E r + E v Thethreegeneraltypesofspectroscopicmethodsareabsorp tion,emission, anduorescence.Absorptionspectraisthespectraoffrequ encieswhichhave beenabsorbedfromthecontinuousspectraasthelightpasse sthroughthematerial,andemissionspectraisthespectraoflineswhichha vebeenemittedby theexcitationofatoms.Flourescenceoccurswhenradiatio nisabsorbedand theexcitedspeciesformedlosespartsofitsenergybynon-r adioactivemeans [24]. 50

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Figure 16.1.3[24] 16.1.1AbsorptionSpectroscopy Figure 16.1.1.1[24] Inabsorptionspectroscopy,theamountofradiationabsorb edbythesampleis plottedasafunctionofthewavelength.Theconcentrationo fthesamplecanbe determinedbytheamountofenergyabsorbed[24].Absorbanc e(A)isgoverned byBeer'sLaw,A= % bC,where % isthemolarabsorptivity,bisthelengthofthe pathincm,andCistheconcentration. Atomicabsorptionspectroscopy(AAS)isespeciallyforgoo dfortheanalysis ofmetals,asitisusefultodecomposethesampleandmeasure theabsorption andemissionspectraofenergycharacteristicoftheatoms[ 24].Theadvantage toAASisthatatomicspectraarelinespectra.2-.4nmwidera therthanbroad emissionandabsorptionbands[24].Linesourcessuchashol lowcathodelamps (Fig4.1.2)areusedfortheincominglight[24]sothatthein cominglightbeamis narrow(Fig16.1.1.2).Thesehollowcathodelampsarespeci cforeachelement, sogenerallyAASislimitedtooneelementatatime. 51

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Figure 16.1.1.2[24] Figure 16.1.1.3[24] Figure 16.1.1.4[24] InFlameAtomicAbsorption(FAA),aliquidsolutioncontain ingthesampleis aspiratedintoaame.Auniformlymixedaerosolofthesolut ioniscreatedby usinganebulizertomixthesolutionwithgaseousfuelandox idant[24].The ionclustersabsorbenoughenergyfromtheheatoftheameto disassociateinto freeatomsinthevaporstate[24]. 16.1.2UV-VisibleSpectroscopy UV-visiblemolecularspectroscopyistheabsorptionofrad iationintheUVvisibleregion.ForUV-visiblespectroscopytobee!ective indeterminingconcentration,thesolutionisgenerallyavisiblecolor.Fort hisreason,UV-visible spectroscopyisgenerallynothelpfulincharacterizingwa ter. 52

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16.1.3Infrared(IR)Spectroscopy Figure 16.1.3:VibrationalandRotationalMotionsofMolecules[2 4] IRspectroscopyistheabsorptionofmoleculesintheinfrar edregion.ThevibrationsexpressedintheIR-frequencyrangearethevibration sbetweenmolecules. Thisisgenerallynothelpfulindissolvedionsinwater,ase venifthewater moleculesbondwiththemetalions,thefrequenciesvibrati onsthatarereleased bythesebondsaretoolowtobepickedupbymostdetectors. 16.1.4X-RayFlourescence(XRF) -Raymethodsaregenerallyusedtodeterminethecompositio nofsolidsamples, anditisusedparticularlyindeterminingthecompositiono fparticulatematter whichhasbeenlteredoutofthewater[environmentalchemi calanalysis].There arenowhandheldXRFmethodswhichcanbeusedoutintheeld. 16.1.5Inductively-CoupledPlasmaMassSpectrometry(ICP -MS) ICP-MScandeterminemetalsandnon-metalsatconcentratio nsbelowpartper trillionbycouplinganinductivelycoupledplasmatoprodu ceionswithamass spectrometertoseparateanddetecttheions. 16.2Conductivity Metalionsdissolvedinwaterhaveacertainconductivitywh ichcanbemeasured asafunctionoftheconcentrationoftheionsdissolvedinth ewater,ifthecurves arecalibratedcorrectly. 16.3IonTestStrips Preparedteststrips,suchasEMQuantfromEMDChemicalsUSA ,asubsidiary ofMerck,Dennmark,areabletodeterminetheconcentration sofparticular metalswithinacertainrange. 53

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PartV ApplicationofMethods Whilethemethodsofpuricationaresite-specicandnotcl imatespecic,the methodsofcharacterizationdependonwhetherornotyouare inatropicalora temperateclimate.Intropicalclimates,coliformbacteri a,whichisconsidered anindicatorbacteriaintemperateclimatesisnotveryreli ableformultiple reasons.Therstreasonisthatsaprophyticbacteriawhich canalsogrowat 37 o C willmeanthatacountofbacterialcolonieswillnotnecessa rilyindicate faecalpollutionofthewater[17].Non-faecalcoliformsca ngrowinveryhot climatessuchasKlebsiellaandCitrobactercanalterthere sultsofafaecal coliformbacteriatestintropicalclimates[17].Pesticid eanalysisintropical areasiscomplicatedformanyreasons,includingtheevapor ationofchemical extractantslikeetherduetoheat,thebreakdownofgaschro matography(GC) equipmentduetounstableelectricity,theconservationof organismsinremote areaswithoutpropercooling,andnanciallimitations[27 ]. 17Implementation:SystemsandInfrastructure 17.1CollectiveSystems Collectivesystemsoftenexistindevelopingcountriesinw hichmultiplemembers ofthecommunityobtaintheirwaterfromaprotectedsource. Thissource isoftengroundwater.Intheglobalsouth,themajorstrateg yagainstwater contaminationistheuseofprotectedsourcessuchasboreho les,standpipes,or wells.Theyareoftenfarfromthehome,andthusrequirecoll ection/transport tothehousewhereitcanbestoreduntilthenexttriptoretri evewater[38]. Contaminationduringanyofthesestagesduringandafterre trievalfromthe protectedsourceisanotherconcern,andsoin-houseltrat ionmaybeneeded toprotectagainstwatercontamination. 17.1.1WellDrilling Sincegroundwaterisnaturallylteredthroughtheground, itismostlyfree ofpathogenslikeprotozoaandsuspendedparticles.Ground watermostlyoriginatedasmeteoriticwater,whichisprecipitationwhichhas inltratedtheground [42].Extractionofgroundwatercanbedoneatanaquifer,wh ichisalocation wheretherockiseitherveryporousorextensivelyfracture d[42].Toacquire cleanground-water,atleast80-mdeepborewellsmustbedug intotheaquifers [32].Inthe1970'sthenon-protUNICEF-India(UnitedNati onsInternational Children'sFund),startedpushingforafastandinexpensiv edrillthatcouldpenetratehardrockupto100meters[32].Ahydraulicdrillwasd evelopedwhich couldcompletethetask,andcostswerebroughtdowninIndia toabout$20/meter,whichislikelythecheapestintheworld.Startinginth e1980's,UNICEF 54

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sponsoredthedevelopmentofaninexpensivehand-pumpwhic hwouldtover theborehole,andtheanswerisUNICEFIndiaMarkII.Eachoft hesehandpumpsservesaround200persons[32].Theimportanceofachi evingwaterthat isdeepintothegroundcannotbeunderestimated,astheworl d'sworstcaseof arsenicpoisoningasof1995occurredwhenshallowtubewell swereinstalledin WestBengalandinBangladesh[32]. 17.1.2SurfaceWaterCollection Anothersourcethatcouldbeusedcollectivelyissurfacewa ter,foundprimarily instreams,lakes,andreservoirs[34].Oligotrophiclakes aredeep,generally clear,decientinnutrients,andmostlydevoidofbiologic allifeforms.Eutrophic lakessupportmorelifeandaremoreturbid,whiledystrophi clakeshavealot ofplantlife;areshallow,colored,andgenerallyhavealow pH[34].Storage reservoirshavealargevolumeofinowrelativetotheirout ow,andthewater issimilartolakewater.Run-of-the-riverreservoirshave alargerateofowthroughcomparedtotheirvolume,andthewaterissimilarto streamwater [34].Theowrateofthewaterisimportant,andinnon-owin gbodiesof watersuchaslakes,water'suniquetemperature-densityre lationshipresultsin theformationoflayersofdi!erenttypesofwater. Often,damsorreservoirswillbearticiallyconstructedb ystreamstoprovideawatersourceforthecommunity.Whenreservoirsarear ticiallyconstructed,factorsa!ectingthequalityofthewaterinclude di!erentvelocities, changeddetentiontime,andalteredsurface-to-volumerat ios[41].Thisimpoundmentofstreamscanbeneciallydecreasethelevelofo rganicmatter, reduceturbidity,anddecreasehardness(calciumandmagne sium).Itcanalso detrimentallydecreasere-aerationleadingtoloweroxyge nlevels,adecreasein mixingofthelayers,anaccumulationofpollutants,andani ncreasedgrowth ofalgae.Sinceoxygenlevelsoftenbecomeverylowatthebot tomofanimpoundedstream,sulfurcompoundsreduce,resultingintheo doroushydrogen sulde.Insolubleiron(III)andmanganese(II)arereduced tosolubleiron(II) andmanganese(II)ionswhichmustberemovedpriortousingt hewater[41]. 17.2IndividualSystems 17.2.1RainwaterHarvestingfromRoofs Rainwatercanbeharvestedfromroofsbyroofcatchments,wh ichareconnected totheguttersanddown-pipesystemstodeliverwatertothes toragetank[66]. Watermeshesorinletltersthatshouldbecleanedregularl yareideallyplaced onthetopofdown-pipestopreventincomingdebrisfromente ringthesystem [66].Thesystemneedstobebuilttodiverttherstowofrai nwater,as theinitialtimeofrainfalliswhencontaminationisatitsp eak[66].WASH, theWater,Sanitation,andHealthbranchoftheWorldHealth Organization, recommendsanautomaticdevicewhichushestherst20-25l itersofruno! fromthesystem[66]. 55

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Thestoragecontainermustbecoveredwithattedtopsothat sunlight reachingthewaterdoesnotpromotealgalgrowth,andWASHre commends thatamosquito-proofmeshisttedovertheopeningstoprev entmosquitos frombreedinginthestagnantwater[66].Thiscandramatica llyreducetherisk ofDengueFeverinareasofhighriskinthedevelopingworld. Monitoringincludescleaningtheltersandcheckingthecleanlinessoft hecatchment/storage area,ensuringthestructuralintegrityoftheysstem,andt hephysicalqualityof rainwaterintermsofturbidity,pH,color,andsmell[66].I nthecaseofstorage tanksmadeofnewconcrete,ferrocementormasonrystorage, pHshouldbe monitoredfrequently[66]. Intermsofpuricationofthecollectedwater,theevaporat ionandsubsequentcondensationofwaterwhichhappensintheupperatmos phereisangood methodofwaterpurication,andsorainwateriscleanexcep twhenitpicksup pollutantsfromtheatmosphereorcontaminationfromcolle ction,storage,and householduse.Faecaldroppings,dirtblownbythewind,ins ects,andlitter areallsourcesofcontaminationintherainwaterharvestin gsystems[66].This hasleadtothedetectionofpathogensliketheharmfulproto zoaCryptosporidium,Giardia,aswellastheharmfulbacterialtypesofCampy lobacter,Vibrio, Salmonella,ShigellaandPseudomonas[66].Thatsaid,rain watercollection systemsaregenerallycleanerthansurfacewatercollectio nsystems[66]. Rainwatertendstobeslightlyacidicmainlybecauseitmixe swiththeCO2 intheatmosphere.Thisproducesthefollowingequilibrium reactionwhenthe carbondioxidegasisdissolvedinthewaterdroplets[newen virochem]: CO 2 ( aq )+ H 2 O ( l ) "# H 2 CO 3 ( aq ) Theweakacidthatformsiscalledcarbonicacid( H 2 CO 3 ),andit'sformation isonlyaround 2 x 10 3 atroomtemperature( 25 o C ),sonotmuchacidisformed proportionally.Still,sincethezinc( Sn )roofsaremadeofalloysthatcontain lead( Pb )andZinc( Zn ),theacidicwatercandissolvethemetalalloysinthe roofssothattheheavymetalsleachintothewatersupply. Otherpotentialdrawbackstorainwateristhatitlackscalc iumandmagnesiumthatwouldbeobtainedfromothermethodsofcollecti on[66].Thisis concerninginareasofmalnutrition,aswatermaybeaprimar ysourceofthese nutrients[66].. 17.2.2ClayPots Inorderfortheclaytobee!ectiveasamethodofpurication ,thejarmustbe shapedonapotter'swheelandredinakiln.InSudan,e!orts toimplement clayjarstopurifythewaterfailed[17].Thereareprejudic esagainstmany potterymakersasalower-skilledwoman'scraft,andinmany areaswhereitis accepted,claypotsareshapedbyhand[17].Moresuccessful hasbeeninthe areasofNigerwhereHausaandDjermavillagesincludemanys killedpotters [17]. 56

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17.2.3Point-Of-Use(POU)Contamination Whetherthesystemthatisusedisindividualorcollectivef orthecommunity, allofthewatercollectedriskspoint-of-usecontaminatio n.Cairncrossetal. (1996)describedtwopathwaysfortransmissionofpathogen s:'domesticdomaintransmission'and'publicdomaintransmission'[49]. Domesticdomain transmissioniswhenpathogensareintroducedinthehouseh old,whilepublic domaintransmissioniswhentheyareintroducedatthesourc e[49]. Obviously,itisnecessarytoaddressbothpathwaysofconta mination,though thereissomedebateonwherethefocusofdevelopmente!orts shouldlie.Van DersliceandBriscoe(1993)arguethatsincedomesticconta minationisa'recycling'ofpre-existingcontaminantsinthehomethattheinh abitantswouldbe accustomedto,publicdomaintransmissionhasmoreofanimp actonpathogen controlinthewatersupply[49].Onthecontrary,Swerdlowe tal.argued fortheimportanceofdomesticdomaintransmission,usingc holeraoutbreaks spreadthroughthehomesasasupportingexample[49]. Aone-yearobservationalstudybytheInternationalWaterM anagementInstitute(IWMI)ontheimpactofusingirrigationwaterfordr inkingwateridentiedpublicdomaintransmissioninPakistan.Thewatersuppl yinthisaridarea ofPakistanisentirelyfromirrigationcanalwater,andapi pefromtheirrigation canalwasconnectedtothesourceofthecommunitieswatera nopenwater tankwithacapacityof 1050 m 3 Figure 17.2.3.1Wide-neckedv.Narrow-neckedpitchers.Narrowne ckedpitchershavebeenshowntoreducePOUcontamination. Duringthisyear-longstudy,sixty-sevenhouseholdsinPun jab,Pakistanreceived newwaterstoragecontainersthatshowedthatpoint-of-use contaminationwas reducedbytheusageofnarrow-neckedpitchersratherthant raditionalwideneckpitchers[49].Itishypothesizedthatthenarrow-neck edpitcherretained moreheatwhichresultedinthedie-o!ofthecontaminatingo rganisms[pointofusecontamination].Furthermore,theresultsdemonstrat edthatcontamination 57

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withindicatorbacteriaisonlyreallyimportantwhentheso urceofthewateris relativelyclean(<100E.coli/100mLofwater)[49]. 18EthicalIssues:WaterasaHumanRight Unlikemedicalcare,thereisnouniversalagreementamongt hedevelopment organizationsonwhetherwatershouldbeconsideredahuman rightorahuman need.Therstinternationalconsiderationofwaterasahum anrightmay bethe1948UnitedNationsDeclarationofHumanRights;adoc umentwhich vaguelyguaranteesstandardsofliving,health,housingan dfood,butnever explicitlymentionswater[43].Theword'water'isnotspec icallymentioned inanyinternationalconventionofhumanrightsonabroader peacetimebasis untila1979conventionfortheeliminationofdiscriminati onagainstwomen, talkingspecicallyaboutaccesstowater,andthenin1989, whenwaterwas alsodiscussedduringaconventionontheRightsoftheChild [43]. Theissueofcleanwateravailabilitygainedattentioninth einternational humanrightscommunityafterthe1978WHOAlmaAtaDeclarati onofthe "HealthforAllby2000"campaignandthe1980-1990Internat ionalDrinking WaterSupplyandSanitationDecade[28].However,thedevel opmentofahumanrightsframeworkbegantoregressinthe1990'sasthedis courseturnedto commodicationofwaterasagood.Duringthattimeperiod,b asicneedswere consideredtobebestprovidedbyprivateindustry.Boththe HagueDeclaration (1989)andtheDublinprinciples(1992)werecreatedontheb asisthatifwater istobemanagede"cientlyanddeliveredtoalargenumberofp eoplethatit mustbetreatedasaneconomicgood[22]. Theterm"humanrights"wasevolvedtohaveacostconditiond uringthis timeperiod,evidentintheassertionof"basicrightofallh umanbeingstoaccess tocleanwaterandsanitationatana!ordableprice,"atthe1 992International ConferenceonWaterandtheEnvironment[43].Byaddingacos tcondition, waterisseennotasarightbutasaneed,andtherecipientsof waterbecomea neweconomicgroup.ThisviewpointhaspersistedintheWorl dBank,seenas recentlyastheWorldBankgroupinthe2009piece"Direction sinHydropower Development"[39]. Incontrast,waterhasbeendeclaredahumanrightthatsuper sedeseconomic needsbyWaterSupplyandSanitationCollaborativeCouncil 'sVision21,the CochabambaDeclaration,theGroupofLisbon'sWaterManife sto,andtheUN CommitteeontheEconomic,SocialandCulturalRights'stat ementontheright towater[39]. The2002UNcommitteestatementwasabreakthroughforwater inthe humanrightsdiscourse,asitdeclared,"thehumanrighttow aterentitleseveryonetosu"cient,safe,acceptable,physicallyaccessiblea nda!ordablewaterfor personalanddomesticuses"(GeneralCommentNo.15(2002): TheRightto Water)[25].ItwasthersttimethattheUnitedNationsexpl icitlyprotected therighttowater,butitwasnotwithoutconditions. AreportcurrentlyhostedontheWorldHealthOrganization( WHO)'sweb58

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sitefragmentsthisrightintoseveralareas.Itdeneswate rforlifeandsurvival; cleandrinkingwaterwaterandsanitationforhealth;water foradequatestandardofliving;waterforfoodandnutrition;waterandsanit ationaspartofright tohousing;waterforfoodpreparation;waterforfoodprodu ction;wateraspart ofrighttodevelopment;wateraspartofrighttonaturalres ources;waterasan elementofrighttoenvironment;waterasanelementofright toproperty[43]. TheWHOdocumenthostedonlinecitestherighttocleanwater asdependentonthesedimensions.Itcitesa1992commentfromtheUNC ommitteeon Economic,Social,andCulturalRights,whichdeneswatera stherighttohousinginthatthe"quantityofwatermustbesu"cientenoughtom eetbasichuman needsintermsofdrinking,bathing,cleaning,cooking,and sanitation,"however theminimumqualityofhouseholdwaterisspecictouse,ast herearelower standardsforwaterandsanitationthandrinkingwater(UNd oc.E/1992/23 generalcomment4)[43].Whiledrinkingandcookingwaterar eprotected,water forfoodproductionisprobablynotcoveredunderminimumne edsinaridareas andagriculturalprodutionrequireshighamountsofwater. Householdwater isthusprioritizedoveragriculturalwater.Despitethevi ctoryforwaterasa humanrightintheUNdocument,onecanseeasoutlinedbyWHO, theserights aredenedashavingcertainprovisions. DespitetheUNstanceonwaterasahumanright,aslateas2008 participants inUNcommitteesreportedotherwise.BarbaraRoseJohnston ,ananthropologistandseniorresearchfellowattheCenterforPoliticalE cology,attendedthe 2008inaguralmeetingofUNESCO-InternationalHydrologic alProgramme'swaterandculturaldiversityinitiativewhichwasheldinPari sandhad15"experts" -ahydrologist,acivilengineer,ananthropologist,ageog rapher,anethicist, andindigenousactivistsrepresentingChina,Japan,Canad a,SierraLeone,the Netherlands,Australia,Paraguay,Mexico,theUK,andtheU S(herself). Shedescribedherexperienceasstartingwiththeinitialqu estion"Whatis water?"Theanswerthatthegroupcraftedwas"Wateristhees sentiallifeblood ofourplanet,withthepowertogenerate,sustain,receive, andultimatelyto unifylife."Laterinthedebatewhentryingtoshowthatthel inkbetweenculture andwatermeantconsideringpathologiesofpower,shesugge stedaddingto thedenition,"waterasafundamentalhumanright,"buther suggestionwas rejected.Thereasoninggiveninthedebatewasthat"linkin grightstocultural diversityimpliesaprivilegedrightofsomegroupsoveroth ers,"thoughitseems contradictorythatthewords"humanrights"couldbeinterp retedasimplying privilegeofonegroupoveranother.Johnstondisagreeswit hthisreasoning andwritesthatthecommitteeonlydevelopedideastofurthe r"problematize" waterandculturaldiversitywithinabio-culturaldiversi tyandhealthframework wherethe"rights-holders"were"stakeholders"[39]. 19MoralityofWater:AnAnthropologicalLens BarbaraRoseJohnstonisnottheonlyanthropologistwhowas invitedbythe UNtogivefeedbackonthewaterdevelopmentparadigm.In200 3theidea 59

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fortheGlobalNetworkofWaterAnthropologyforLocalActio n(NetWA)was presentedbytheUnitedNationsEducational,Scienticand CulturalOrganization's(UNESCO)InternationalHydrologicalProgram(IHP) attheThirdWorld WaterForuminKyoto,Japan.Theideaofthenetworkisforant hropologist toshareinformationonwaterpuricationinthecontextofd evelopment.From the2005documentingtheformationofNetWA:[25] In2003theideafortheGlobalNetworkofWaterAnthropology forLocalAction(NetWA)waspresentedbytheUnitedNations Educational,ScienticandCulturalOrganization's(UNES CO)InternationalHydrologicalProgram(IHP)attheThirdWorldW ater ForuminKyoto,Japan.Theideaofthenetworkisforanthropo logisttoshareinformationonwaterpuricationintheconte xtof development. Theroleofanthropologistisnotjustlimitedtoimprovingi ntegrationitisalso concernedwiththeethicsofdevelopment.Modernanthropol ogicalcritiqueof thedevelopmentdiscoursecanbegeneralizedasfallingint wocategories:reform andradicalchange.Thoseinthe'reform'categoryarguetha tdevelopment isamethodofcombatingpoverty,butthatitwouldbemoree!e ctiveifit allowedforanthropologicalinput.Thoseinthe'radicalch ange'categoryargue thatdevelopmentisamethodofextendingcapitalistreign, andthatwemust workoutsideofthediscourseinapost-developmenteratoam elioratecurrent conditionsofinequalitysuchaswaterdeprivation.Thisli neofthoughtfollows BarbaraRoseJohnston's,ifthecommitteesdoreallyfuncti ontojustifyby problematizationtheroleofnancialinstutions. Theinvolvementofanthropologywithindevelopmentbeyond culturalstudiesofpovertyisstillrelativelyrecent.Pertinentquesti onspostedbyanthropologistsincludewhetherornotpovertyisclassiedorconstr ucted,andwhether ornotthetechnicalsolutionstoinequalityproposedbydev elopmentdomore harmthangoodbydivertingattentionfromstructuralprobl ems. Opinionsonthesetopicsarewidelyvaried,splitbetweenca mpsthatdevelopmentcanbeeitherharmful,ine!ectual,orhelpful.Withint hepastfewdecades, oneofthemaincritiquesbyanthropologistshasbeenoffood aid,particularly thatwhichisshippedtoAfricaafterbeingoverproducedbyt hecornindustry whichissubsidizedintheUnitedStates.Emergencyfoodrel iefisviewedin thecriticalanthropologicallensasine!ectualagainstth epathologiesofpower whichcontributetofamine.Whiletherehasbeenlotsoflite ratureonfamine, therewaslittlefocusbyanthropologicalspecicallyonwa teruntilrecently. Thelittleearlyanthropologicalliteratureofwaterthate xistedmainlyfocused onculturalreasonsthatpeopledidnotadheretopublicheal threcommendationssuchashandwashing,disposingproperlyofwaste,and boilingwater[28]. ItwasmilitantanthropologistslikeNancyScheper-hughes andcriticalmedicalanthropologistssuchasMorgan(1993),Morsy(1996),an dNavarro(1984) whobranchedawayfromtheconventionalnotionthatlocalcu ltureprevents acceptanceofoutsidesolutionstohealthproblems[28]. 60

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Fromthecriticalmedicalanthropologicalperspective,'h ealth'isdenedby Morganin1993as"thesocialandhistoricalrootsofdisease andhealthcare,with particularattentiontotheexistenceofstratisedsocial relationswithinaworld economicsystem"[28].Thebasisofthisanalysiscanbefoun dinLindenbaum andLock(1993),andLockandScheper-Hughes(1996),though anthropologists beganlookingatsu!eringinthecontextofstructuralviole nceandalackof agencyearlierthanthat.Su!eringwasseeninthelackofcon trolovernatural resourcesbeginninginthe1980s,includingworkbyanthrop ologistsincluding Armelagoset.Al(1992),Bennett(1995),andWhiteford(199 7)[28]. Thus,anthropologistsnowexaminewater-relatedhealthis suesnotonlyin thecontextofculturalofdiseaseandhygiene,butasanissu eofpathologiesof powerthatlimitequaldistributionofwater.Waterscarcit yisthenexamined similarlytothewaythatfaminehasbeeninfoodaid,whichis thatinorder tosolvetheproblemsofstarvationanddehydrationwemustc onsiderthem aschronicproblemsstemmingsystemicallyinstructuralvi olence:populations alreadysovulnerablethattheydonothavetheresiliencyto weatherthrougha dryseason. Sowhilethereareareasthatareseverelylackinginwaterdu etofactorslike drought,theproblemofwaterscarcityisprimarilyaproble mofdistribution. Waterscarcitye!ectsthepoordisproportionatelymoretha nitdoestherich,and thepoorfrequentlypaymorethantherichbecausetheydonot haveavoiceto advocateforthemselves.Whenwaterislimited,poorpeople whoarealreadyat risktohealthfactorsduetocrowdingandlackofmedicalcar e,areataneven higherriskforcholera,skinandeyeinfections,becauseth eycannotpractice safehygienepractices[28].IntheValleyofMexico,progra mshaverestricted pipeddrinkingwatersystemsinpoorruralareasinfavorofp rovidingwaterto wealthierurbanareas,industry,andirrigation,asshowni nethnographiesby Bennett(1995),Flores(1995),andGarciaLascurain(1995) [28]. TheanthropologistFloresarguesinhis1995paper,"Thosew hohavefewer economicresourcesandwhoconsumelesswaterpayforaliter ofwateratthe highestprice"[28].GarciaLascurainshowspublishedstat isticsin1995from 1991supportingthis.In1991,peoplelivinginthea#uentar easofMexicoCity areapaidmex$50/1,000Lforwaterpumpeddirectlytotheirh omes,whichput thewaterauthorityatanetlossof$210.00(Flores1995).In thatsameyear, peoplelivinginpoorareasintheoutskirtsofthatareapaid mex$500-$1,200per 200Ldrumtwiceaweek[28].GarciaLasurainobserves,"lack ofhygiene,thirst, healthproblems,andconstantnervoustensionaretheprinc ipalconsequences ofthelackofwater"forpeoplelivinginthepoorurbansetti ngsofthevalleyof Mexico"[28]. 20GenderConsiderations Eventhoughdrinkingwaterfallswithinthedomesticrealm, andwomenare thoughtofastheprimaryindividualswhoobtainanddistrib utewaterforthe household,programsforwaterqualitywereoriginallydesi gnedbymen,imple61

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mentedbymaleengineers,andtargetedatmaleleaders.Furt hermore,studies havealsoshownthatobtainingthewatertakesalotofwomena ndgirl'sdaily energyandthatthewomencansu!erphysicalinjuriesaaresu ltofcollecting thewater[67].Theissueofgenderwasnotconsidereduntilt he1970'swith theWomeninDevelopmentframework(WID),whichcontinuest obenotonly prevalentbutalsoproblematic.Inthe1970'sand1980'swom enwereessentializedas"guardiansoftheenvironment,"andtheinvolvement ofwomeninwater projectswasgreatlypromotedforeconomicreasons[57]. TheissueofWIDwasinitiallyformallyraisedataninternat ionalscaleatthe 1977UnitedNationsWaterConferenceatMardelPlata.After wards,theframeworkwasemployedattheInternationalDrinkingWaterandSa nitationDecade (1981-1990)andtheInternationalConferenceonWaterandt heEnvironment inDublin(January1992)whenDublinexplicitlyrecognized thecentralroleof womenintheprovision,managementandsafeguardingofwate r[46].Women werereferredtoinAgenda21(paragraph18.70),andtheJoha nnesburgPlan ofImplementation(paragraph25),aswellastheresolution establishingthe currentInternationalDecadeforAction,'WaterforLife'( 2005-2015)[46]. Incorporatingwomenintowaterprojectsisseenaseconomic allybenecial formanyreasons.Therstisthattheyaretheonesresponsib leforthewater, andthesecondisthatthetimewomensavewhentheydonothave totravel longdistancestogatherwatercanbeusedtogenerateincome ThispromotionofwomeninaWesternlensandthepromisethat they willbemoreeconomicallytrustworthyhasproducedtrainin gsofwomenas watercaretakers,healtheducators,motivators,andhandp umpmechanics[57]. However,thereissomeevidencethatthisactuallydeterior atethequalityoflife forwomenastheysu!erfromalackoftime,orcreateconicta ndincrease levelsofdomesticviolenceastheirmalecounterpartsfelt disempowered. TheprevalentdiscoursehassinceswitchedfromWomeninDev elopment toGenderinDevelopmentinanattempttoproduceamoreholis ticviewof therolesandtherelationshipsbetweenwomenandmen.Manys tudieshave focusedonhowwomenhaveexperiencedmoreanxietyandstres soverwater pollution,ooding,andwaterinsecurity,butfewhavelook edatgenderedroles inthehousehold.AmberWutichisananthropologistwhowent toVillaIsrael inCochabamba,aftertheWaterWarof2000,inwhichtherewas athreemonth periodofunrest.VillaIsraelwasfoundedapproximately20 yearsagobymainly QuechuanminerswhohadbeendisplacedaftertheBolivianmi ningindustry collapsed.AlloftheindividualsinVillaIsraelpurchasew aterfromvansthat travelaroundandsellindividualcontainersofwater.Trad itionalwatergovernanceinthetownwascontrolledbymen,whilewomenemployed byBolivia's PLANE(PlanforEmergencyEmploymentProgram)hadwomenove rseethe constructionofaseriesofcanals[67]. TheresultsofWutich'ssurveysshowedthatwhilewomenrepo rtedeconomizingmore,andlosingmoreworkbecauseofwaterinsecurit y,menwerejustas likelyasfemalehouseholdheadstoreportfeelingworry,bo ther,andangerwith afamilymember.Throughherethnographyshewasabletodisp elcommonconceptionsthatatleastinVillaIsrael,themanalsohassubst antialresponsibilities 62

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forhouseholdacquisitionofchildcareandtheirmentalhea lthwasa!ectedjust asthewomen'swere.Wutichreportsontheunexploredareaof howmenare a !ectedbyfeelingsofguiltduringtimesofwaterscarcityc onsideringtheirrole inBoliviancultureasthebreadwinner[67]. Wutich'sconsiderationofgenderindepthisnotthenorm.Ev enafterthe discourseshiftedfrom"WomeninDevelopment,"to"Genderi nDevelopment," mainstreamdevelopmentfocusedmainlyonempoweringwomen basedonWesternidealsratherthanimplementingplansbasedonlocalrea litiesofgenderrelations.TheanthropologistPagedocumentshowwomenhaveh istoricallyhad asuccessfulproactiveroleinthedevelopmentofwatersupp liesinCameroon, thoughtheyacteddiscursively.Pagearguesthatinprogram swhichfailtotake intoaccountthehistoricrolesofwomeninwaterdistributi on,westernmodes ofempowermentmayactuallyworktodisempowerlocalwomen[ 57]. ExamplesoftheimplementationofWestern-basedfemaleemp owerment ratherthanathoughtfulgenderedapproachcanbefoundinth eUNpolicy brief,"Gender,Water,andSanitation,"bytheInter-agenc yTaskForceonGenderandWater(GWTF),createdforthecurrentInternational DecadeforAction, 'WaterforLife,'whichcitesexamplesthatitstatesasinco rporatinggender[46]. AnexamplegivenbytheInter-agencyTaskForceonGenderand Water isfromNigeriawheretheconstructionofatouristresortin theOduboplatformdecreasedwateravailabilityforthelocalpeople.The NigerianConservationFoundation(NCF)startedawatershedmanagementproje ctontheObobu plateauin1999whichelectedwomenleadersandencouragedf emaleinvolvement.Thenetresultwassupposedtoreducedtimecollecting waterthatgives themmoretimetowork,andthereportskimsoveraconictbet weenBecheve womenandFulanitribesmen,sayingthatitwasresolvedover timethroughconict.Thisisaprimeexampleofaprogramwhichignorespatho logicalproblems ofpowerinfavorofatechnicalsolutionwhichdoesnotaddre ssthestructural cause(theconstructionoftheresort).Itisalsoanexample ofhowlittlegender relationsaretakenintoaccountwhenwomenareprimarilyem poweredandmen feeldisempowered. YetanotherexamplethattheUNInter-agencyTaskForceonGe nderand WatergivesistheHotovillageofBaluchistaninPakistanwh erethewomen followastrictformofpurdah.Theparticipatoryactionres earchteamwentto helpthevillageimproveitswatermanagementin1994,andfo rayeartheaction teamwasnotgivenpermissiontomeetthemenofthevillage.T hewomenwere nallyabletoparticipateinajointmeetingandbothgender sdraftedsolutions. Thewomen'ssolutionwasconsideredmorecost-e!ectiveand soitwaschosen overthemen'ssolution.Thereportmentions,butalsogloss esover,thebacklash thatthewomenexperiencedfromtheirmalecounterparts[46 ]. TheUNInter-agencyTaskForceonGenderandWaterreportcha mpionsa recentincreaseinthenumberofwomenappointedaswaterand environmental ministers,asoflate2005,therewere40femaleministersof waterorenvironment.TheseincludetheMinisterofStateforWaterofUganda ,H.E.Maria Mutagamba,whoischairoftheAfricanMinisterialCouncilo nWater(AMCOW),andoftheAfricanMinistersInitiativeonWASH(Water ,Sanitation, 63

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andHygiene),supportedbytheWaterSupplyandSanitationC ollaborative council[46].However,itisunclearwhetherornotwomeninp ositionsofpower representsabroaderplantoincreasegenderdiversityorif itisasassomeanthropologistsargue,simplyameasureof'style.'Byinstit utingfemalesinroles ofpositionsofpower,thesituationcanbeaestheticallyim provedwithoutever addressinggenderdynamics. 21SustainabilityandAppropriateTechnology Appropriatetechnology,whichtakesintoaccountthecultu ralandnancial realityoftherecipientoftechnology,hashistoricallybe enacornerstoneofinternationaldevelopment.Sustainabilitywithintheengin eeringcodeofethics setforthbytheAmericanSocietyofCivilEngineersinclude sappropriatetechnology.Theemphasisonsustainabilityisamorerecentidea ,anditispossibly atconictwithappropriatetechnology,assometimesthesy stemswhichare designedasappropriatetechnologyarenotbuilttolast.Th eanthropologist Elmendorfnotedin1981thatupto50percentofallruraldrin kingwaterand sanitationsystemsbecomeinoperableafter5years[28]. 22ActiveInternationalAgencies EngineersWithoutBorders(EWB)isthenameofmultipleorga nizationsinternationallywhichserveimpoverishedareasoftheworldi nwaterpurication. EWB-USAistheorganizationbasedintheUnitedStates,andi thasbothprofessionalanduniversity-basedchapters.Theorganizatio nhasaminimum5-year commitmenttotheareainwhichtheyareworking.Theemphasi sinEngineers WithoutBordersisoftenonwaterpurication,thoughthisc anbeoneproject inalargerprogramthatachaptertakeson. PottersforPeaceisaUS-basednon-protwhichwasfoundedi n1986that useslocalpotterymakersandimpregnatestheclaywithcoll oidalsilverbefore placingitinaplasticdistributiontank. Figure 22.1:ThedesignofaPottersforPeacelter[50] 64

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Figure 22.2:AlocalwomenmakingtheclaypotforaPottersforPeace lter [50] Figure 22.3AlocalwomennexttoacompletedPottersforPeacelter [50] Therearemanyotherorganizationswhichareworkingintern ationallytobring cleanwatertodevelopingcountries.Amongthemareunivers itieswhichare workingindependently.In2004,MITreceiveda$115,000gra ntfromtheWorld BanDevelopmentMarketplaceGlobalCompetitiontoinstall alterin25 Nepalesevillages.Theltersthattheydevelopedarecalle dArsenicBiosand Filters(ABF)(Fig.22.4),andtheyremovearsenicandpatho gens.Thelter shellismadeofplasticorconcrete,standsonemeterhigh,a ndisabout0.3 metersinlengthandwidth.Itislledwithgravel,coarsesa nd,nesand,and ironnails,andthelterscanprocess15-30litersperhour[ 56]. 65

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Figure 22.4ArsenicBiosandFilterinNepal;developedbyMIT[56] Theselterswerebuiltafterasiteassessmentwhichtookin toaccountallofthe ltersmadebyvariouscompanies,includingtheNepalCeram icCo-operative whichmanufacturestheNepaleseceramiccandlelters,han dmadelocallyina smallworkshop(Fig.22.5).TheUSNGOIndustryforthePoor, Inc.manufacturestheHaitianpurier(Fig22.6),whichconsistsofastr ing-woundsediment lterandanactivatedcarbonlter[29]. Figure 22.5NepaleseCandleFilter[29] Figure 22.6HaitianPurierUsedinNepal[29] 66

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OtherNGO'swhichdevelopwaterpuricationfortheglobals outhinclude VestergaardFrandsen,whichisnotanon-prot,butoperate sunderagrowingbusinessmodeltheycall"protforapurpose."Theycrea tetheLifestraw, whichtheyclaimhasalongevityofmorethan18,000L.Aninde pendentassessmentdoneattheUniversityofNorthCarolinaChapelHi llshowedthat puricationwasabout90-99%fortheLifestrawlter[60]. 67

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PartVI CaseStudy:Honduras Inordertoseehowwaterpuricationworksrst-hand,Irese archedagroup whichwouldbeactivelygoingonatripduringthetimeIwaswr itingmythesis. IsettledonSanDiegoStateUniversityEngineersWithoutBo rders(SDSUEWB),andattendedtheirmeetingsviaSkype. InJanuary2011,ItraveledtoHonduraswithSDSU-EWBonthes iteassessmenttripthatlastedtwelvedays.Thepurposeofthistr ipwastogeta rst-handunderstandingofallofthedi!erentdimensionso fimplementationof waterpuricationsystemsintheglobalsouth.Ihavesinceb eenworkingwith SanDiegoStateinformulatingaplanforfuturetripstother egion. Tejerasisatownofabout660peopleinthemunicipalityofOl anchito, situatedinNorthernHonduras,ontheoutskirtsofthePicoB onitoNational Park.Becausethetownisatthefoothillsofamountainrange ,thewaterwould berelativelycleanwithoutthepresenceofcattleandagric ulturalcontamination furtherupstream.Tejerasispartofadecentralizedsystem of27townseachwith theirownwaterboards("juntas")coordinatedbythelocalN GO,AJAASPIB (theAssociationofAdministrativeWaterBoardsoftheSout hernSectorofPico Bonito).AJASSPIBreceivesfundingfromEcoLogic,aCambri dge,MA-based 68

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NGO,whichhelpsfundthecostofthechlorinewhichisusedto purifythe water.Thewaterisobtainedbyadamwhichisplacedinthestr eamwhich runsdownhilltowardsthetown.WhiletheclimateinTejeras ismostlydrydue toitslocationinavalleybeyondthemountainsofPicoBonit oNationalPark,it isalsopronetotropicalstormswhichcanresultintorrenti aldownpours.These infrequentbutpowerfulrainstormsbringsludgeandrocksd ownthehillside whichclogthepipesandcanhaltdeliveryofwaterformoreth anaweek. Inmyroleastheeducationallead,andassupportingleadind eveloping thehealthinterviewsurvey,Ihelpedadministersurveysto 13outofatotal 14householdsinterviewed,asampleofapproximately13%of thehouseholds receivingwaterinTejeras.Awatersamplewastakenfromeac hhousethat wasvisitedinthehealthsurveysothattheycouldbetestedf orchlorinelevels, pHandforindicatorbacteria.Aprofessionalengineeracco mpaniedtheteam tohelpperformthetests,whichweredonewithoutanincubat orfor48hours usingwatertestsorderedforfreefromthecompany3M.Other membersofthe teamusedhand-heldGPSunitstocreateamapofthetowninclu dingthewater distributionsystem. Theteamrealizedthattheteststhatweresentfromthelocal NGO(nongovernmentalorganization)thatshoweduncountableamoun tsoffaecalcoliform contaminationwereunrepresentative.Thewaterteststhat wetookwerecoming upclearforallmicrobialcontaminationaswellaschlorine .ThelocalNGOmay haveprovideduswithtestsfromaperiodofextremepollutio n,suchaswhen ananimaldiedinthewatersourceandputried.Calculation softheowrate duringtheJanuary2011siteassessmenttripdemonstratedt hatpuricationwas insu"cientandinconsistent. Therewerechallengesbasedonthepoliticalstructureande conomicconstraints.ThepresidentoftheWaterJuntawasalsothepasto r,andhewas brotherswithothermembersoftheJunta,includingthepaid watercaretaker. Whenweapproachedthetownleaderstoaskwhytherewasnochl orineshowinguponthewatertests,theyexplainedthatthewatercaret akerhadmade amistakeinpreviousdaysandhadonlyplacedhalfofthebago fchlorinein thewatersupply.Inthisimpoverishedarea,110households payalittlemore thanadollaramonthforwaterwhichisdeliveredtothehouse sindividually.A fractionofthisdollarisusedtopaythepart-timesalaryof thewatercaretaker, thoughhedoesnotmakeenoughmoneytoproperlymaintainthe system,ashe hasafulltimejobatthelocalbananafactory. Sincethecaretakercanworkonlyverylimitedhours,cleanw atercanbe lackingentirelyfromseveraldaysupuntilmorethanaweeka tatime.These periodsofwaterfaminehaveforcedvillagememberstotrave landobtaintheir ownwaterortoappropriatecostswhichwouldotherwisegoto foodormedical billsintobuyingbottledwater. EWB-SDSUhassincestartedplanningforanAugusttripforas econdsite assessment.Currentplansforimplementationincludeimpr ovingthewater whichischanneledtothehomesinadditiontoafurtherpuri cationmethodfor drinkingwaterwhichcouldbebottledandsoldatafractiono fcurrentwater pricestocreateastreamofrevenueforthepeopleofTejeras 69

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PartVII Experiment Thisexperimentisbasedo!ofthe2010journalarticle,"Met aloxide/hydroxidecoateddual-medialterforsimultaneousremovalofbacter iaandheavymetals fromnaturalwaters."byV.Meeraetall[15].Sandwascollec tedfromthe localriverbed,coatedwithmanganeseoxideandironoxide, andthenwater collectedfromatinroofwaspassedthroughthesand.Theman ganeseoxide coatedsand,whichhasanegativesurfacechargeatneutralp Hissupposed toattractthepositively-chargedmetalions,whiletheiro n-oxidecoatedsand, whichhasapositivesurfacechargeatneutralpHissupposed toattractthe negatively-chargedmaterialsinthecellsofbacteriaThey foundthemethod tobeverye!ectiveinremovingbacterialandheavymetalcon taminationfrom ZincandLead,whichleacho!ofthetinroofduetotheslightl yacidicnature ofrainwater. Thisexperimentwasoriginallyintendedtoexploreremoval ofbothZinc andlead,butduetotherelativelylowsolubilityandconduc tivityoflead,the calibrationcurvecouldnotbecalculated.Ionstripswereo rderedweeksbefore theexperimentwasperformedbutneverarrived,soasaresul ttheexperiment isonlydoneforzinc. 23Purpose Toexplorethefeasibilityofmanganese-coatedsandtodecr easetheconcentrationbelowacceptablelevelssetbytheUSPublicHealthServ icelimitforzinc of5mg/L.Theexperimentusesthewater-solublezincsulfat e,7-Hydrateto obtainzincionsinthewater.Theresultantreactionis: Zn 2+ + SO 2 4 + H 2 O Zn 2+ + HSO 4 + OH Thepresenceofthehydroxideionmeansthatthesolutioniss omewhatbasic.Theconcentrationofthezincafterpuricationwillbe determinedbased ontheconductivityofthesolution,asthemethodusedinthe Meera'sexperiment,AtomicAbsorptionSpectroscopy(AAS)isnotavailabl eatNewCollege ofFlorida. 24InstrumentsandMaterials pHmeter ECTestr11DualRange(EutechInstruments) SandfromNewCollegeofFloridaSailClub,SarasotaBay 70

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HotPlate (2)6-inchlong,1.5-inchdiameterPVCPipes (2)adjustablemetalclamps linen Chemical Mol. Wt (g/mol) Amt Hazards 8%NitricAcid ( HNO 3 ) 63.01 ~600 mL Strongoxidizer;corrosive;liquidand mistcancausesevereburnstoall tissues;andinhalationmaycause lungandtoothdamage.Itmaybe fatalifswallowedorinhaled.If swallowed,donotinducevomiting, butgivelargequantitiesofmilkor water.[6] DeionizedWater ( H 2 O ) 18.02 >20L none 37.5% Hydrochloric acid ( HCl ) 36.46 73mL Corrosive.Liquidandmistcancause severeburnstoallbodytissue.May befatalifswallowedorinhaled,and inhalationcancauselungdamage.If ingested,donotinducevomiting. Drinklargequantitiesofmilkor water.[5] Potassium Permanganate 158.03 35g Strongoxidizer;corrosive.Willcause burnstoanyareaofcontact. Harmfulifswallowedorinhaled.if swallowed,donotinducevomiting butdrinklargequantitiesofwater. [9] ZincSulfate 287.56 ~20g Harmfulifswallowedorinhaled. Causesirritationtoskin,eyes,and respiratorytract.Ifingested,donot inducevomiting,butdrinklarge quantitiesofwater.[10] 24.1Procedure Beforebeginning,acalibrationcurveforzincinDIwatermu stbeperformedso thattheconcentrationcanbedeterminedfromthereadingso ftheconductivity meter. 71

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24.2PreparationofSand The500mLsandmustrstbepreparedbeforecoatingbysoakin gitinan8% nitricacidsolutionin5di!erent250mLbeakersforapproxi mately1hour.The sandwasthendriedinanovenwithtemperaturesslightlyhig herthan 105 o [15]. 24.3CoatingtheSand Figure 24.3.1PotassiumPermanganate Thecoatingrecipehasbeenmultipliedbyafactorof.44,sot hat35gofpotassiumpermanganateismixedinto440mLofboilingwater,and2 20mLof acid-washedsandisaddedslowlytotheboilingmixture.Ove raperiodof approximately9minutes,73mLofconcentratedhydrochlori cacidareadded dropwise.Themixturethenboilsforapproximately10morem inutesbefore beingremovedfromtheheat. Themixtureisthenlteredbyusingalterontopofafunnel. Usinga vacuumtube,suctionenoughwaterintoa500mLErlenmeyera sktogetthe sandtoapproximatelyapHof7[15]. Figure 24.3.2Preparingthemanganese-oxidecoatedsand 72

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24.4PreparationofZincSolution ZincsulfateismixedintoDIwatertoproduce6g/mL,aboveth elimitof 5g/mL.TheamountofzincsulfatetoaddtotheDIwaterwasdet ermined usingthemolecularweights,andthefactthatthestoichiem etricratiosforthe dissolutionofzincsulfateintoionswas1:1,asshowninthe Purposesection. Atom/Molecule StandardAtomicWeight (g/mol) Zinc(Zn) 65.37 ZincSulfateHeptahydrate ( ZnSO 4 ) 7 H 2 O ) 287.53[10] 65 37 gZn 1 moleZn ( 1 mol (( ZnSO 4 ) H 2 O ) 287 53 g ( ZnSO 4 ) H 2 O ( 1 molZn 1 mol ( ZnSO 4 ) H 2 O = 2274=22 74% (6) Thismeansthatforeverygramofzincsulfateused,only.227 4gwilltheoreticallybezincion.Toproduceaconcentrationof2.999g/ Lzincions,azinc sulfatesolutionofconcentration13.188g/Lmustbeproduc ed.Inthisexperiment,theconcentrationismadein100mLbatchesso1.319go fzincsulfate wereaddedtothesolution. 24.5PreparationoftheFilters ThelineniscutsothatittsoverthePVCpipes,anditissecu redwithan adjustableclamp.ThePVCpipeisattachedbyaclampandplac edovera collectionbeaker(Fig24.5.1). Figure 24.5.1PreparedFilters 73

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25ResultsandConclusion Figure 25.1CalibrationCurveofZincSulfate Zincshowedastrongandconsistentcalibrationcurve(Fig2 5.1),ensuringthat thisisapotentialfordeterminingtheconcentration.Expe rimentswererunin parallelsothattheycouldbecompared.One100mLbatchofzi ncsolutionwas prepared,thetemperatureandconducitivitywerebothmeas ured,andthenthe batchwassplitintotwo50mLbatcheswhichwerelteredthro ughthesand. Thishasbeenreectedintables26.1and26.2bytrials(a)an d(b).Though thetrialswerecompletedinparallel,themanganesecoated sandlterhadtobe donetoensurethatthetimingwascorrect.Thetimeinsecond srepresentsthe timeatwhichthesolutiontooktotravelthroughthesand,an ditrepresents owrate(owratecanbecalculatedbydividingthevolume-5 0mL-bythe time). Unfortunately,afterthesandwascoateditbecamepowdery, cakedinto amud-likesubstancewhenwet,andlostitscrystallinestru cture((Fig26.2). Thiscouldbeduetothestructureofthesand,whichwasnotst ableenough toundergothehighlevelsofacidinvolvedinthecoatingpro cess.Thisimplies thattheexperimentcannotbereproduceduniversally,butm ustbetailored toeachindividualsourcedependingonthemolecularstruct ureofthesand. FutureexperimentsdoneinSarasotamaybenetfromusingth esandfoundat LidoBeachorSiestaKey,bothofwhichhavesandwhichisquar tz-basedand unlikelytostructurallydegrade.Anothersourceoffailur ecouldbeaninitial 74

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lowpHnormalizationduetoinadequatewashingwithDIwater beforecoating withpotassiumpermanganate. Theconsistencyofthecoatedsandmeantthattheow-throug hratewas muchslowerthantheuncoatedsand.Initialplansweretouse multiplebatches ofsand,butbecausetheow-throughratewassolowlargebat chesofsand couldnotbenormalizedtoahighenoughpH.ThepHissoimport antbecause adsorption,themainmechanisminsandltration,isheavil ydependentona normalizedpH.Morethan10LofDIwaterwaspouredthroughth ecoated sandbutthepHwouldnotnormalizeto7,andthesandturnedth ewatera consistentdarkbrowncolor.Toequalizetheowrates,di!e rentamountsof sandandmanganese-oxidecoatedsandwereused.100mLofsan dwasused intherstlter,whileonly40mLofmanganese-oxidecoated sandwasused inthesecondlter.Thee!ectivenessoftheuncoatedsandl terintrial1b suggeststhatthenewlterismoste"cientatadsorptionini tiallybutbecomes saturatedafterthersttrial. Whilesignicantgainsweremadewiththesandlter,theman ganese-oxide coatedsandltershowedanincreaseinconductivity.Clear ly,conductivity doesnotworkasamethodforevaluatingthee!ectivenessoft hemanganeseoxidecoatedlter,assomeofthemanganesewasleachedout increasingthe conductivityofthesolution.DIwaterbroughttheacid-was hedsandtopHof 7.51,buttheDIwatercouldonlybringthemanganese-oxidec oatedsandtoa pHof5.92.AsadsorptionisheavilydependentonpH,itcanbe estimatedthat themanganese-oxidecoatedsandlterwasnotatoptimalads orptioncapacity. Thefollowingchartshowsthetrialswhen2.5g/Lwasltered throughboththe regularsandandthemanganese-oxidecoatedsandlter. Trial No. Pre-Filtration ( S ) Manganese-oxide CoatedSandFilter ( S ) Time (s) Temperature ( o C ) 1a 5200 5600 97 23.2 2a 5200 6000 98 20.7 3a 5100 6200 100 20.1 4a 5200 6100 99 20.5 Table 25.1Conductivitypre-andpost-ltrationofmanganese-ox idecoated sand. Trial No. Pre-Filtration ( S ) UncoatedSand Filter( S ) Time (s) Temperature ( o C ) 1b 5200 890 89 23.2 2b 5200 2300 86 20.7 3b 5100 2400 87 20.1 4b 5200 2600 88 20.5 Table 25.2Conductivitypre-andpost-ltrationoftheuncoateds and. 75

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Figure 25.2Sandpost-manganesecoating,afterDIwaterhasbeenl tered throughitusingasuctiontechnique,whichaccountsforthe crackingpattern. 76

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PartVIII Conclusion Whilemuchofthisthesisisatechnicaloverview,prescribi ngtechnicalsolutionsisnottheanswertotheproblemofcleanwateravailabi lityintheglobal south.Providingtheglobalsouthwithtechnologiesdevelo pedintheglobal northcreatesadependency-developmentrelationshipwith outsustainability. Furthermore,thereisnoglobalmodelofwaterpuricationd evelopment,as eachtechniquemustbelocalizedfortheregionandthepollu tantswhicharein thewater. Ifthetechnologytopurifywatercanbemadeincountryithas thepotential tobemadesustainablyandthepotentialtoaddresssystemic issuesofinequality byempoweringlocalindividualstocreatetheirownproject s.Bycreatingabase knowledgeofwater,howitfunctions,andthedi!erenttypes ofpurication,new methodscanbeemployed.Developmentprojectscanincorpor atenumerous technologieswhichhavealreadybeenrecognizedanddevelo pedlocallysuchas theinvolvementofclayortheleavesoftheMoringaplanttoc oagulatethewater beforepurication. Theexperimentwaschosenbecauseitwascreatedbyresearch ersinIndiato solveaproblemwhichislocallyarealchallengewaterwhic hiscollectedfrom tinroofsusingoneofthemostnaturalmethodsofpuricati on(evaporation andprecipitation),andusinglocalmaterialssuchasriver sand.Theinvestigationintothatmethod,however,provedthatdevelopmentp rojectsmustbe locally-specicandcannotrelyonaglobalmodel,astheche micalcomposition ofthesandinIndiawasunlikethatoftheNewCollegeSailClu b.Evenifthe sanddidnotdegradeinqualityasitdidintheexperimentper formedhere,there isadi!erenceintheoverallchargeonthesandduetoitsmole cularstructure thatwilla!ectnotonlywhichmoleculesitwillbeabletoads orbbutthepHat whichadsorptionisoptimized.Othervaryingfactorsinclu desizeofthesand, aslargergrainswillproduceafastsandlterwhilesmaller grainswillproduce aslowsandlter. Onthelocallevelinsmallcommunities,somemethodsofwate rpurication canbemorehealthfriendlythanthoseusedindevelopedcoun tries.Thisis becausethecommunitiesareoftensmallerandmorespreadou t,sosmallerscalemethodsaremorefeasible.However,withoutasophist icatedstructure, thesemethodscanbeharmful.Oneofthemostpopularmethods ofwater puricationemployedindevelopingcountries,aswasinthe caseofHonduras, wastheuseofatypeofchlorinecalledhypochlorite.Withou tthebreakup ofhumicmaterialsbefore,potentiallydangerouscarcinog enscanforminthe water,andsohypochloritetreatmentshouldnotbeusedasab aselineora standaloneasitsooftenis. Developingalternativetechnologiesandtestingthewater canbeavery expensiveanddi"cultprocess.EvenatNewCollege,thestan dardmethods likeAtomicAbsorptionSpectroscopycouldnotbeused,anda conductivity 77

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meterhadtobeusedinstead.Implementationisanevenmored i "cultprocess, asresources,socialandpoliticalinfrastructure,andgen derinequalityallmust beconsideredforsuccesstooccur.Whileitwouldbeheralde dasasuccessif theUNdevelopmentgoalofhalvingthenumberofindividuals wasachieved, itisimportanttoconsiderthecostincurredintheprocess ensuringthata projectwhichintendstohelpadisadvantagepeopledoesnot servetohurtthem more. References [1]academic.brooklyn.cuny.edubiologybio4fvpagechiti n.html. [2]Eightallotropesofcarbon.png. [3]en.wikipedia.orgwikilealginsaure.svg. [4]ga.water.usgs.goveduwatercycle.html. [5]http://www.jtbaker.com/msds/englishhtml/h3880.ht m. [6]http://www.jtbaker.com/msds/englishhtml/n3660.ht m. [7]wikis.lib.ncsu.eduimages115ba1.png. [8]www.bio.miami.edudana226226f092.html. [9]www.jtbaker.commsdsenglishhtmlp6005.htm. [10]www.jtbaker.commsdsenglishhtmlz4560.htm. [11]www.rpi.edudeptchemengbiotechenvironmembranescr oss.htm. [12]Method1604:Totalcoliformsandescherichiacoliinwa terbymembrane ltrationusingasimultaneousdetectiontechnique(mimed ium).Technical report,USEnvironmentalProtectionAgency,2002. [13]Method1623:Cryptosporidiumandgiardiainwaterbyl tration/ims/fa. Technicalreport,USEnvironmentalProtectionAgency,200 5. [14] MicroltrationandUltraltrationMembranesinDrinkingWa ter .American WaterWorksAssociation,2005. [15]MansoorAhammedandV.Meera.Metaloxide/hydroxide-c oateddualmedialterforsimultaneousremovalofbacteriaandheavym etalsfrom naturalwaters. JournalofHazardousMaterials ,181:788793,2010. [16]AntoineA.C.M.BeenackersAjayKRay.Novelphotocatal yticreactorfor waterpurication. AIChEJournal ,44,2004. 78

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