!!!! Carbon!Fibre!Reinforcement!of!Ceramic!Water!Filters!

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1 CarbonFibreReinforcementofCeramicWaterFilters by DianaNicholson AThesis Presentedto TheUniversityofGuelph Inpartialfulfillmentofrequirements forthedegreeof MasterofAppliedSciences in EnvironmentalEngineeringandInternationalDevelopmentStudies Guelph,Ontario,Canada DianaNicholson,August2012

2 DianaRachelleNicholson UniversityofGuelph,2012 ABSTRACT CARBONFIBREREINFORCEMENTOFCERAMICWATERFILTERS Advisor: ProfessorEdwardMcBean Thisresearchstrivedtoexaminethepotentialforcarbonfibretoimprovethestrength characteristicsofceramicwaterfilters(cwfs)toimprovetheirlengthofuseinthefieldwhile discsweremadeexploringseveralconfigurationsofcarbonfibrereinforcementandweretested that,whiletheparticularcarbonfibreconfigurationsexploredinthisstudydidnotincreasethe minimallydetractingfrombacteriaremoval.thisindicatesthatthereinforcementofcwfshas potentialandfurtherresearchshouldbeconductedtodetermineanappropriatereinforcement configurationtoimprovetheirstrengthcharacteristics.giventhatcwfsaregainingmore widespreaduseinmanycountriesworldwide,extendingtheirlifespanofusewouldhave significantvalue.

3 Acknowledgements Iwouldliketothankmyadvisor,Dr.EdwardMcBean,fortheguidance,advice,andlightningfast responsetimehehasprovidedmethroughoutthepasttwoyears.iwouldalsoliketothanka numberofpeoplewithoutwhomthiswouldnothavebeenpossible:mirnaderghazali,joanne Ryks,RyanSmith,BarryVerspagen,CarlyGenn,JordanVallis,BillMorton,andSteveWilson.I wouldliketosayaspecialthankyoutobarrday,inc.ofcambridge,ontarioandthecanadian WildRiceMercantileofThunderBay,Ontariofortheirgenerousdonationsofcarbonfibreand ricehulls,respectively. Tomyfriendsandfamily(new,old,andreacquainted):thankyouforyourencouragementand support. iii

4 TableofContents 1. Introduction ResearchObjectives ThesisOrganization References LiteratureReview CurrentStateofDrinkingWaterAccessWorldwide TheRolesofPOUWaterTreatment POUWaterTreatmentTechnologies FiltrationTechnologies CeramicWaterFilters EffectivenessofCeramicWaterFilters OperationalIssueswithCWFs FibreReinforcedCeramicMatrixComposites FactorsAffectingStrengthening VibrioCholeraeattenuationbyCeramicWaterFilters CausesandSymptoms PreventionandControlMeasures RemovalofVibrioCholeraefromDrinkingWater TheUseofCeramicWaterFiltersinEmergencyResponse References StudyDesignandMethods CeramicWaterFilterDiscDesign FlowRateTesting BacteriaAttenuationTesting Limitations References Results StudyObjectives Results FlowTestData BacteriaAttenuationData References ConclusionsandRecommendations Summary Conclusions Recommendations...91 iv

5 ListofTables Basson,2011)...16 CWFDiscDesignScenarios ListofFigures woventowsoffibres.(a)to(d)showplanviewwhile(e)and(f)areedgeviews. (SmithandYeomans,nodate)...20 glass(davidge,1987) andtntcleft) v

6 ListofAppendices AppendixA:CarbonFibreSpecificationSheet AppendixB:CompleteDataSet vi

7 ChapterOne: Introduction 1

8 1. Introduction AccordingtoUNICEFandtheWorldHealthOrganization(WHO),theMillenniumDevelopment Goal7C,tohalveby2015,theproportionofthepopulationwithoutsustainableaccesstosafe drinkingwater,hasbeenreachedasof2010.however,hugedisparitiesexistbetweenaccessby therichversusthepoor.additionally,780millionpeople,morethanonetenthoftheglobal population,stilldonothaveaccesstoapotabledrinkingwatersource.(unicefandwho,2012) Withoutdirectaccesstowaterinthehome,watermustbecollectedelsewhereandthen transportedto,andstoredin,thehomepriortouse.microbialcontaminationofwaterduring thecollection,transportation,andstorageofwaterislikely.anumberofstudieshaveshown thatwaterstoredinthehometendstobemorecontaminatedthanthesourcewater(wrightet treatmenttechnologieshavebeenidentifiedassuccessfulinterventionsforfillingtheservice gapofprovidingpotablewatertohouseholdswherecentralized,pipedwatersystemsarenot possible,orwherewateriscollectedelsewhereandstoredinthehome(thompsonetal.,2003; interventionsarecapableofdramaticallyimprovingthemicrobialwaterqualityatthe householdlevelandreducingtheriskofdiarrhealdisease(sobsey,2002;who,2007). Theresearchpresentedinthisthesisinvolvestheinvestigationandmodificationofawidely usedpouwatertreatmenttechnology,theceramicwaterfilter(cwf).thesefiltershavebeen showntobeeffectiveatattenuatingpathogensfromdrinkingwaterandreducingtheincidence ofdiarrhealdisease,however,thecwfstypicallyonlylastapproximatelytwoyearsmainlydue 2

9 tobreakage,eitheroftheceramicfilterelement,thespigot,orthecontainercoupledwith limitedavailabilityofreplacementpartsincommunities.(brown,2007)thisresearchspecifically focusesonmodifyingthecwfrecipebyaddingcarbonfibrereinforcementinordertoattempt toimprovethemechanicalcharacteristicsoftheceramicfilterelementandimproveitslengthof useinthefield.giventhatthesefiltersaregainingmorewidespreaduseinanumberof countriesworldwide,extendingtheirlifespanofusewouldhavesignificantvalue.thisresearch willaddtothepresentliteratureexaminingcwfsandtheuseofadditivesineffortstoimprove theircharacteristics ResearchObjectives Thisresearchstrivestoexaminetheuseofarecipeadditive,carbonfibre,toimprovethe mechanicalcharacteristicsofcwfswhilemaintainingorimprovingexistingflowandbacteria attenuationabilities.therearefourprimaryobjectivesofthisresearch: PerformE.coliattenuationtestingontheCWFdiscstodeterminebacteriaremoval characteristics;and, 4. PerformstructuraltestingontheCWFdiscstodeterminestrengthcharacteristics ThesisOrganization Thisthesisconsistsofthefollowingchapters: 3

10 Chapter2: LiteratureReview Thischapterpresentsaliteraturereviewondrinkingwaterresourcesinthedevelopingworld, andcholeraattenuation,asapplicabletothecurrentresearch. Chapter3: StudyDesignandMethods Thischaptersummarizesthestudysetupanddesignandthedatacollectionmethodsusedin thisresearch. Chapter4: Results Chapterfourpresentstheresultsfromtheflow,E.coliattenuationandequibiaxialflexural strengthtestsperformedonthecwfdiscs.statisticalrelationshipsbetweenvariousfactorsare examined. Chapter5: ConclusionsandRecommendations Thefinalchapterofthisthesissummarizesthefindingsoftheresearchpresentedandprovides overallrecommendationsandareasofapplicablefutureresearch References Brown,J.M.(2007).Effectiveness*of*Ceramic*Filtration*for*Drinking*Water*Treatment*in* Cambodia.Unpublished.DoctorofPhilosophy.UniversityofNorthCarolina.ChapelHill. Clasen,T.F.,andBastable,A.(2003).Faecal*contamination*of*drinking*water*during*collection* and*household*storage:*the*need*to*extend*protection*to*the*point*of*use.journalofwater 4

11 Jagals,P.,Jagals,C.,andBokako,T.C.(2003).The*effect*of*container?biofilm*on*the* microbiological*quality*of*water*used*from*plastic*household*containers.journalofwaterand Sobsey,M.(2002).Managing*water*in*the*home:*accelerated*health*gains*from*improved*water* supply.who/sde.wsh/02.07.who,geneva,switzerland. Sobsey,M.(2006).Drinking*water*and*health*research:*a*look*to*the*future*in*the*United*States* Thompson,T.,Sobsey,M.,andBartram,J.(2003).Providing*clean*water,*keeping*water*clean:* UNICEFandWHO.(2012).Progress*on*Drinking*Water*and*Sanitation:*2012*Update.NewYork, NewYork:UNICEF. Wright,J.,Gundry,S.,andConroy,R.(2004).Household*drinking*water*in*developing*countries:* A*systematic*review*of*microbiological*contamination*between*source*and*point?of?use. 5

12 ChapterTwo:LiteratureReview 6

13 2. LiteratureReview 2.1. CurrentStateofDrinkingWaterAccessWorldwide AccordingtoUNICEFandtheWorldHealthOrganization(WHO),theMillenniumDevelopment Goal7C,tohalveby2015,theproportionofthepopulationwithoutsustainableaccesstosafe drinkingwater,hasbeenreachedasof2010.however,hugedisparitiesexistbetweenaccessby population,stilldonothaveaccesstoapotabledrinkingwatersource.(unicefandwho,2012) Inadequateaccesstopotabledrinkingwatercontributestothestaggeringburdenofdiarrheal diseaseworldwide.diarrhealdiseaseisendemicincommunitiesthatlackaccesstoimproved watersupplies.accordingtothewho,88%ofthe4billioncasesofdiarrheathatoccurannually areattributedtocontaminatedwaterandinadequatesanitationandhygiene(who,2007). incomecountries,andamongthetopthreecausesofdeathinchildrenundertheageoffive causingupto milliondeathsperyear(Lopezetal.,2006;Koseketal.,2003).Drinking contaminatedwatercanalsoreducepersonalproductivetimewithwidespreadeconomic effects.diarrhealdiseasesareassociatedwithawiderangeofconsequences,including decreasedfoodintakeandnutrientabsorption,malnutrition,reducedresistancetoinfection, andimpairedphysicalgrowthandcognitivedevelopment, relateddiseasesmaypreventchildrenfromattendingschool,resultingin443millionmissed schooldaysperyear(undp,2006).problemsassociatedwithunsafedrinkingwaterare significantbarrierstodevelopment,bothhumanandeconomic. 7

14 Althoughdrinkingwaterisonlyoneofseveralpossiblepathwaysformostwaterborne pathogens,ithasbeenshownthatinterventionstoimprovewaterqualityaregenerallyeffective inreducingdiarrhealdiseaserates.therefore,microbialcontaminationofdrinkingwaterin communitieslackingimprovedwatersuppliesislikelytocontributesignificantlytotheburden morbiditymaybepossiblethroughtheuseofwaterqualityimprovementsalone(clasenet al.,2007).sobsey(2002)foundawiderangeofdiarrhealdiseasereductionsrangingfrom6 90%,dependingonthetypeofHWTintervention,exposedpopulationandlocalconditions.As such,theprovisionofpotabledrinkingwaterisclaimedtobethepovertyreductionintervention thathasthegreatestoverallimpactonnationaldevelopmentandpublichealth(who,2006). Centralizedwatertreatmentanddeliverysystemshavemanyadvantagesintermsofwater safetyandaccesshowevermaybedecadesawayfromimplementationinmanyareasofthe world.theinstallationofcommunalfacilitiessuchasboreholes,standpipes,andimprovedwells representamajorstrategyforsecuringaccesstoimprovedwatersourcesinareaswithout centralizedsystems.however,withoutdirectaccesstowaterinthehome,watermustbe collectedelsewhereandthentransportedto,andstoredin,thehomepriortouse.microbial contaminationofwaterduringthecollection,transportation,andstorageofwaterislikely.a numberofstudieshaveshownthatwaterstoredinthehometendstobemorecontaminated thanthesourcewater(wrightetal.,2004;clasenandbastable,2003;jagalsetal.,2003). successfulinterventionsforfillingtheservicegapofprovidingpotablewatertohouseholds 8

15 wherecentralized,pipedwatersystemsarenotpossible,orwherewateriscollectedelsewhere andstoredinthehome(thompsonetal.,2003;sobsey,2006).accordingtoawhoreview, improvingthemicrobialwaterqualityatthehouseholdlevelandreducingtheriskofdiarrheal disease(sobsey,2002;who,2007).theyarebeingpromotedbecausetheyreducetheriskof contaminationbetweenthetimeofwatercollectionandconsumption TheRolesofPOUWaterTreatment POUwatertreatmenttechnologiesareanyofarangeofdevicesormethodsusedforthe purposesoftreatingwaterinthehomeoratthepointofuseinothersettings.mostpou technologiesareintendedtoreducemicrobialpathogens,althoughsomealsoreducechemical andradiologicalcontaminants.pousystemscomprisearangeofaccessibletechnologieswith thegoalofincreasingaccesstopotablewateratthelowestpossiblecosttoindividualsand communities.thesesystemsareincreasinglypromotedaspracticalsolutionstoproblemsof contaminateddrinkingwaterqualityinpoorareaswherecollectingwateroutsidethehomeand storingitforhouseholduseistypical(sobsey,2006).theuseofpousystemsmaycontributeto acceleratedhealthgains fromimprovedaccesstocleandrinkingwaterwherecentralized watertreatmentanddeliverysystemsareunavailableorinadequate(sobsey,2002). POUtreatmentisalsosuitedtocrisisinterventionswhereemergencysuppliesofpotablewater areneeded(curtisetal.,2000;mongetal.,2001;who,2005).breakdownsinwatersupply systemscanoccurasaresultofnaturaldisasters,warandhumanconflict,orsimplyinadequate maintenanceofinfrastructure(curtisetal.,2000).poutreatmentcanalsobeusedin 9

16 temporarysettlementssuchasrefugeecampsorshelters(robertsetal.,2001;who,2006; DoocyandBurnham,2006).ThistopicisexploredfurtherinSection POUWaterTreatmentTechnologies KeyreviewsofPOUwatertreatmentandproperstoragetechnologieshaveadvancedthe currentknowledgeoftheseinterventionsandtheiruseinpoorareasofcountriesworldwide (Sobsey,2002;Lantagneetal.,2006;HIP,2006;IRC,2005).PhysicalmethodsforPOUwater treatmentincludeboiling,heating(usingfuelandsolar),filtering,settling,andultraviolet(uv) precipitation,ionexchange,chemicaldisinfectionwithgermicidalagents(primarilychlorine), andadsorption.combinations,ormultiplebarriers,ofthesemethodssimultaneouslyor sequentiallysuchascoagulationcombinedwithdisinfectionoftenyieldpromisingresults (Souteretal.,2003).Thesuccessoftheseinterventionsishighlycontextspecificwithnoone technologyormethodrepresentingauniversalbestsolution.availabilityofmaterials,qualityof rawwateravailable,culturalfactorsandpreferencesorcostmaydeterminewhereeachof theseismostsuited(sobsey,2002) FiltrationTechnologies POUfiltrationtechnologiesincludeclothorfibrefilters,membranefilters,porousceramic filters,andgranularmediafilters.thesefiltersreducemicrobesbyacombinationofphysical andchemical(and,insomecases,biological)processesincludingphysicalstraining, sedimentationandadsorption.filtrationtechnologiesareincreasinglybeingusedinpoorareas 10

17 wherechemicaldisinfectionorboilingmaynotalwaysbepracticaloreffective(colwellet al.,2003). Traditionalmembranetechnologyisgenerallyexpensiveandthereforelargelyunknownfor cloth,havebeenrecommendedforreducingvc*inwaterwhentheseareassociatedwith copepodsorothereukaryotesinwater(colwelletal.,2003).theseclothswillnotsignificantly retaindispersedbacterianotassociatedwithcopepods,othercrustaceans,suspended sediment,orlargeeukaryotesbecausetheporesoftheclothfabric(>20μm)arenotsufficiently smalltoexcludebacteria,butwhereappropriatethesefilterscanhavesignificanthealth impacts. Granularmediafiltersincludethosecontainingsand,diatomaceousearthorothersusing discreteparticlesaspackedbedsorlayersofsurfacesthroughwhichwaterispassed.other granularmediafiltersarebiologicallyactivebecausetheydeveloplayersofmicrobesonthe surfaceoforwithinthegranularmediummatrix.thisbiologicallyactivelayerretainsmicrobes biologicallyactivesurfacelayerthatcanbedosedintermittentlywithwaterhasbeendeveloped calledthebiosandfilter,whichisanintermittentlyoperatedslowsandfilter(iossf)(stauberet al.,2006). 11

18 Onefiltrationtechnology,ceramicwaterfilters(CWF),hasgainedwidespreaduseasan inexpensivemethodtotreatmicrobiallycontaminatedwater.thefilterelementsaremadefrom porousfiredclayandcomeinavarietyofconfigurations CeramicWaterFilters worldwideincludingcambodia,kenya,guatemala,nicaragua,ghana,etc.theyaremadefrom locallyavailableclay,sand,andanorganicmaterialsuchassawdustorricehusks.theorganic materialisusedtofacilitateflowratesthroughthefilterasitburnsoutduringthefiringprocess leavingbehindsmall,interconnectedpores.alayerofsilvernitrateorcolloidalsilverisapplied to the surfaces of the filter to provide an additional disinfection mechanism and to prevent growthofbacteriawithinthefilteritself(lantagneetal.,2010). proper storage reservoir as shown in Figure and Figure Water passes through the porous ceramic filter element by gravity at 1 to 3 L/hr, into the receiving container. Treated water is then dispensed from the receiving container by a tap to prevent post@filtration contaminationofthewater.theceramicfiltercanholdapproximately10lofwaterwhilethe plasticreceptaclestores20loftreatedwater. 12

19 Figure2W1:CeramicWaterFilterSchematic Locallyproducedceramicfiltershavetheadvantagesofbeinglightweight,portable,relatively notsignificantlychangewatertasteortemperatureanddoreduceturbidity:aesthetic improvementsthatmaybestrongmotivatorsforuseofthetechnologytotreathousehold water.(brown,2003;roberts,2004;clasenetal.,2004)therawmaterialsusedtomanufacture thefilterelementsaresourcedlocallywiththeexceptionofthesilversolution.silverisobtained fromaninternationalsupplier,yetrepresentsasmallfractionofthetotalcostofthefilter (aboutus$0.20perfilter).filterscostbetweenus$5andus$30andhaveanaveragelifespan oftwotothreeyears.(kallmanetal.,2011)aretrospectivestudyoffiltersdistributedin Cambodiafromtwolocalfilterfactoriesfoundthat:50%ofpeoplehadfunctionalfilters18 monthsafterdistribution,and20%hadfunctionalfilters36monthsafterdistribution.(brownet al.,2007)theceramicfilterelementsurfaceiscleanedthroughperiodicscrubbingtoreduce surfacedepositsthatslowfiltrationrates. 13

20 Figure2W2:ExampleofaCeramicWaterFilter(Murphyetal.,2009,Brown,2007) EffectivenessofCeramicWaterFilters CWFsvarybyoveralldesign,productionmethod,clayandothermaterials,qualityassurance andqualitycontrolprocedures,typeofburnoutmaterial,firingtemperaturesandmethods, chemical(e.g.,colloidalsilver)amendmentsandapplicationmethod,flowrateconsidered acceptable,andmannerinwhichtheflowrateismeasured,andothercharacteristics. (Sobsey,2002;Cheesman,2003;Dies,2003;Lantagne,2010)Duetothefactthatthedesign, materialsavailable,andmethodsusedvariesfromcountrytocountryitisdifficulttomake generalitiesaboutcwfsasawhole.pathogenattenuationdataforonefilterdesignmaynotbe comparabletootherdesignsand,insomecases,separatebatchesfromthesamefactorymay vary. Pathogenattenuationviaceramicfiltrationmayinvolvetwoprimarymechanisms,physical removalandinactivation.filtrationbysizeexclusionremoveslargermicroorganismssuchas 14

21 protozoansandsomebacteriaandisattributabletotheinitialfilterporesizes.poresizesvary withceramicmaterial,organicmaterial,firingtemperatureandprocess,etc.surfaceassociation andthefiltercakethatdevelopswithfilterusemayalsoremovesmallerbacteriaandviruses. (Bielefeldtetal.,2009)Microbeorchemicalinteractionssuchassorptionwiththefilter s ceramicsurfacemayalsoeffectreductionsofkeycontaminants.additionally,theapplicationof silversolutionsincreasespathogenattenuationbyinactivatingbacteriaandvirusesand inhibitingbiologicalgrowthwithinthefilter.(lantagne,2001a) Several studies have quantified the CWF attenuation of bacteria, such as fecal coliform or Escherichia coli, which serve as indicators of pathogenic microorganism disinfection. Simonis andbasson(2011)createdasummarytable(table2@1)ofworldwidetestingdoneoncwffrom 2000@

22 Table2W1:SummaryofworldwidetestingonCWFsfrom2000W2010(modifiedandadditional dataaddedtosimonisandbasson,2011) References Parameter Reduction % LRV(log 10 ) Remarks Dies(2001) Escherichiacoli >98 Katadynfilter Sagara(2000) Escherichiacoli NepaleseCWF Giardialamblia 4.6 Lantagne(2001) Cryptosporidium parvum 4.3 Totalcoliform 98.2 PottersforPeace(PFP)Nicaragua Fecalcoliform 97 Fecal streptococcus 82 Hwang(2002) Escherichiacoli PFPfiltersinNicaraguaover6 Totalcoliform 89.3 months Lantagne(2001), Escherichiacoli GM98 Brown(2007):90@99% Roberts(2004), Diarrhealdisease Mean46 Dukeetal.(2006) Totalcoliform 94@99.9 Terafilfilter(Low2002) AndHwang(2003) Escherichiacoli 88 WhiteClayCWF Dies(2003) Escherichiacoli >98 WhiteClayCWFwithcolloidalsilver Escherichiacoli >98 HongPhucCWF Coulbert(2005) Escherichiacoli 99.8 PozzaniCWF Franz(2005) Escherichiacoli 92@100 Tested5typesofcommercialfilters McAllister(2005) Bacteria 99 PFPwithcolloidalsilver Viruses 20 Clasenetal.(2006) Diarrhealdisease Mean39@44 VanHalem(2006) Escherichiacoli 3@6.8 Clostridumspores 3.3@4.9 Baumgartner Escherichiacoli 99.8 Filtronwithcolloidalsilver (2006) Totalcoliform 99.4 WSP(2007) Escherichiacoli upto Diarrhealdisease 50 Brown(2007) Escherichiacoli 1.8@2.4 Laboratorystudies Bacteriophage MS2 1.3@1.9 Oyanedel@Craver Escherichiacoli >97.8 andsmith(2008) Viruses >90 BrownandSobsey Escherichiacoli Mean99 2.1@2.9 (2010) Bacteriophage MS2 90@99 1.2@4.1 Murphy(2010) Escherichiacoli 0.5@2 SurfacewaterfieldtestsinCambodia Non@peerreviewedstudiesbyRoberts(2004),Lantagne(2001a),Dukeetal.(2006b),VanHalem (2006),Mattelet(2006)andothershavesuggestedthatlow@costceramicwaterfiltersdohave thepotentialtoprovidemicrobiologicallyimprovedwatertousersasindicatedbyareductionin surrogatesfordiseasecausingmicrobes.theaveragebenchmarkstandardforescherichiacoli 16

23 effectivenesswas97±3%,whereasvirustestingeffectivenesswaslimited.theattenuationdata thatexistsprovidesastartingpointforestablishingausefulguidelinefortestinglowcostcwfs andmakesitclearthatcwfs,usedatalocallevel,greatlyimprovethemicrobialqualityof householdwaterresultinginadramaticdecreaseindiarrhealinfectionratesanddeath. (SimonisandBasson,2011) OperationalIssueswithCWFs Somepathogenattenuationstudiescompletedinthefieldhavefoundmorebacteriainthe effluentthaninthesourcewater.lantagne(2001)reportedeffluentwaterconcentrationsof 4900,4320,and1920CFU/100mLoftotalcoliform,fecalcoliform,andE.coli,respectively, comparedto124,70,and0intheinfluent.incambodia,17%ofallfiltersampleshadhigher 2007)InastudycompletedinNicaragua,Hwang(2002)foundhigherEcoliandtotalcoliform concentrationsintheeffluentintwoandfour,respectively,of49filtersinhomes.thishasbeen attributedtobacteriagrowthintheplasticreceptacletank.thespigotisnotlocatedatthevery bottomofthetanksoitdoesnotdraincompletelywithnormaloperation,whichcouldallow regrowthofpathogensinthestagnantwater.(bielefeldtetal.,2009) Astudy(Brown2007)conductedover44monthsinCambodiareviewedtherateandreasonsfor filterdisuseoverthetestperiod.approximately2000householdfilterswereintroducedbytwo disusewasfoundtobeapproximately2%permonthafterthefilterswereimplementedandthe mainreasonwasduetobreakage,eitheroftheceramicfilterelement,thespigot,orthe 17

24 containercoupledwithlimitedavailabilityofreplacementpartsincommunities.otherreported reasonsfordisuseincludedthefilterbeingtoosloworotherwiseunabletomeetthehousehold drinkingwaterdemand,thefilterhadpasseditsrecommendedusefullifeasindicatedbythe manufacturer(somemanufacturersimprintan expirydate ontothesurfaceoftheirfilters) andsoitwasassumedtobenolongereffective,orusersgaveorsoldittoafriendorrelative. Onaveragefiltersareusedfortwoyears FibreReinforcedCeramicMatrixComposites Ceramicmaterialsoftenexhibitacombinationofusefulphysicalandmechanicalproperties, includinghighrefractoriness(abletoretainphysicalshapeandchemicalidentityathigh temperatures)andcompressivestrength.however,theirapplicationsarerestrictedduetotheir waspromptedbytheneedformaterialswiththeadvantagesofceramicscombinedwith increasedtoughnessandtensilestrength,andareducedvariabilityofstrength.(phillips,1989) Theideaoffibrereinforcementingeneralsuggeststhatsignificantstrengtheningwillonlyoccur iftheelasticmodulus(theratioofaforceexerted linearstress totheresultantdeformation linearstrain)ofthereinforcingfibresisgreaterthanthatofthematrix,andiftensilestresses canbetransmittedfromthematrixtothefibres.iffibresoflowerelasticmodulusareused,the ultimatefailurestresswillbereducedbecausethematrix,ratherthanthefibres,willcarrya greaterproportionoftheappliedload.(bowen,1968;donaldandmcmillan,1976; Davidge,1987)Thematrixbondswiththefibres,protectsthemfromsurfacedamagedueto abrasionorcorrosion,separatesthefibresandminimizesthepropagationofbrittlecracks 18

25 betweenthefibres.stressesmaythenbetransmittedtothefibresthroughthebondwiththe deformationofthematrix.(donaldandmcmillan,1976)thefibrereinforcementmayalso increasethespallingresistanceofthematrix. Thereinforcingphaseinacompositematerialcanbepresentinanumberofdifferentformats: classifiedbylengthandlayoutwithinthematrix.(smithandyeomans,nodate)thedegreeof strengtheningabletobeachieveddependsonthelengthandorientationofthereinforcing fibres.thecompositeisstrongeralongthedirectionoforientationofthefibresandweakestina directionperpendiculartothefibre.therearegenerallythreeclassifications:continuousfibre, definedasacompositeinwhichthereinforcingphaseconsistsofacontinuousfibre,continuous acompositeinwhichthereinforcingfibresarediscontinuouswithinthematrixorhaveoneor bothendsinsidethestressfieldunderconsideration.(astmd3878)randomlyorientedfibres consistoffibresthatarenotarrangedinadeliberatepatternwithinthematrix.discontinuous fibrescanberandomlyorientedwithinthematrix. 19

26 Figure2W3:Schematicshowingvarioustypesofreinforcement:(a)particles,(b)platelets,(c) whiskers,(d)unidirectionalcontinuousfibres,(e)crosswplycontinuousfibres,and(f)woven towsoffibres.(a)to(d)showplanviewwhile(e)and(f)areedgeviews.(smithand Yeomans,nodate) Continuousfibrereinforcementsbringaboutthelargestchangesinpropertiesduetothe homogeneityofthereinforcement.(smithandyeomans,nodate)thefibres,ideally,areatleast 15timeslongerthanthecriticallength(theminimumlengthnecessarysuchthattheentireload compositesareveryanisotropicandfrequentlyspecialfabricationmethodshavetobeused. (Davidge,1987)Fordiscontinuousreinforcementthefibresareshorterthanthecriticallength andarethereforelesseffectiveinstrengtheningthematerial,howevertheycanbefabricated intocomplicatedshapesmorequickly,easilyandatalowercostthancontinuousfibre reinforcedcomposites.randomlyarrayedfibrereinforcementsaretheleasteffectivein 20

27 strengtheningthematerialsincetheproportionoffibresalignedinthedirectionofstressis reduced,howeverthematerialisisotropicandcheapertofabricate.(donaldand McMillan,1976;Davidge,1987)Additionally,somefibreswilllieapproximatelyperpendicularto reducingthestrengthofthecomposite.(donaldandmcmillan,1976) Themainpurposeofreinforcingceramicsistoincreasestrengthintheformoftoughness. Toughnesshasbeendefinedastheabilityofamaterialtowithstandthermalandmechanical shockwithoutbreaking.(bowen,1968)the workoffracture isdefinedastheworkdoneper unitareainpropagatingacrack(donaldandmcmillan,1976)andisfrequentlytakenasa measureoftoughnessofamaterial.(bowen,1968)ceramicswithnoreinforcementexhibitlow workoffracturevaluesduetotheeaseatwhichcrackscanpropagatethroughthem.fibre reinforcementisabletolimitthegrowthofcracks,therebyincreasingtheworkoffracture,by restrictingthecracklengthtothedistancebetweenfibresand,wheretransversefibresbridge thecrack,bylimitingtheextenttowhichthecracksurfacescanseparatetothedegreeofelastic straininthefibres.(bowen,1968)anothercontributiontotheworkoffractureisthework requiredtopullthefibreendsoutofthematrixagainstthebondingforcesofthematrixtothe reinforcingfibres. Thechangeinthemechanicalresponseofceramicswithfibrereinforcementaddedisbelieved tobetheresultofacomplexmicrofailureprocessinthematrix.insuchcomposites,thefirst fractureeventisconsideredtobeaveryimportantpartofthebehavior,becausetheapplication rangeissometimeslimitedbythefirstfracturebehaviorofthecomposites.(gotoand 21

28 failurestrainofthematrixislessthanthatofthereinforcingfibresand,referringtothelettered pointsonthecurve,theusualsequenceofeventsisasfollows: A:initialcrackformationinthematrix, B:initialfailureofthefibrereinforcement,and (Davidge1987;GotoandKagawa1994) Figure2W4:ComparisonofstressWstraincurvesforbendinginglassandcarbonfibreWreinforced glass(davidge,1987) FactorsAffectingStrengthening Indesigningapracticalceramiccompositeanumberoffactorsneedconsidering:thermal expansionofthematrixandreinforcingfibres,chemicalcompatibility,andthenatureof interfacialbonding.(bowen,1968;caoetal.,1990)thedifferentialthermalexpansionofthe 22

29 matrixandreinforcingfibresisaveryimportantfactorincompositematerialsasitdetermines resultantmechanicalproperties.(donaldandmcmillan,1976;caoetal.,1990)sincetheyare causedbytheinherentpropertiesofthecompositecomponents,theseresidualstressescannot beavoided.theymayresultinpositiveornegativeeffectsdependingontheirdirectionand magnitude.(kuntzetal.,1993)residualstressesinfluencematrixfractureintwoways:stresses paralleltothefibressuperimposedirectlyontotheappliedstressandmaycausematrixcracks, andstressesperpendiculartothefibresaffectthefrictionalforcesbetweenthefibresandthe matrix.(marshallandevans,1985;kuntzetal.,1993)ifthereinforcingfibrecontractsmorethan thematrix(providedthefibreremainsbondedtothematrix)thefibrewillbesubjectedtoa residualtensilestressandthematrixtoaresidualcompressivestressandviceversa.itis preferableifthethermalexpansionvalueofthereinforcingfibresandthematrixarekeptas similaraspossiblebut,ifnot,itispreferableifthethermalexpansionofthefibreisgreaterthan thematrixasthefibreismorecapableofwithstandingtensilestrains.(davidge,1987) Anotherconsiderationisthechemicalcompatibilitybetweenthematrixandthereinforcing fibres.thefibrediameterisanimportantparameterinthiscase:theratesofanychemical interactionsgenerallyincreasemarkedlywithdecreasingfibrediameterasthisincreasesthe interfacetovolumeratio.(davidge,1987)indesigningafibrereinforcedceramic,chemical compatibilityofthefibresandmatrixmayimposesevererestrictionsonappropriatematerial combinations.(bowen,1968) 23

30 Theinterfacialpropertiesbetweenthefibreandmatrixarecrucialindeterminingthe mechanicalbehaviourofacomposite.ifthematrixbondsverystronglytothereinforcingfibres, thecompositebehavesmoresimilarlytoanunreinforcedceramicandcrackswillbeableto propagateunimpededthroughthematrix.(donaldandmcmillan,1976)however,astronger discretegapattheinterfaceoraweakenedinterfaceisideal,asthiswillcauseapropagating cracktodeflectlocallyalongtheinterfacesothatthematerialbehavesasa tough composite. combinedtoreduceresidualstressesandeliminatecatastrophicfailures.(donaldand McMillan,1976;Caoetal.,1990;Murthyetal.,1996)Aninterfacethatistooweakwillallow reachedtoachieveoptimalstrengthening.(donaldandmcmillan,1976;davidge,1987; Chiang,2001) FlexuralTestingofFibreWReinforcedCeramics Withinabrittlematerial,thereisamultitudeofmicroscopicstructuralandmaterialdefectsin defectsactasminutestressconcentrationsinthematerialandastheappliedloadisincreased, fracturewillinitiateandpropagatefromoneofthem.sincethedefectsarerandomly distributedthroughoutthematerialandareofrandomseverity,thereisaninevitableinherent variabilityinthestrengthofnominallyidenticalbrittlespecimensoverandabovethatwhich maybepresentbecauseofvariationsincompositionordetailsofmanufacture.(stanley,2001) 24

31 Duetotheirbrittlenature,bothunreinforcedandreinforcedceramicsaredifficulttotestin puretension,compression,orshear,primarilyduetodifficultiesingrippinganduniformly loadingthebrittlespecimen. Thetensilestrengthofthematerialcanbeverysensitivetoflawsanddefects,includingthose inducedduringspecimenfabricationaswellasstressconcentrationsinducedbythegripping method.purecompressivestrengthisdifficulttoobtainbecausebrittlematerialstendtobe muchstrongerincompressionthaninshear.eveninapurecompressiontest,theshearstresses thatoccurat45degreestothedirectionoftheappliedcompressiveforcemaycausepremature shearfailure.(adams,2008) Instead,aflexuraltestisoftenusedasthespecimensimplyrestsonasupportandisloadedin anappropriatemannerdependingonthespecimenshape.inaflexuraltest,thestressstateis neitherpure(itvariesfromtensionononesurfacetocompressionontheotherwithshear presentaswell)noruniform(itvariesalongthelengthofthespecimen).intheflexuraltest,a brittlematerialwillusuallyfailatitstensilesurfaceand,assuch,thetestmeasuresthetensile strength.thesensitivitytodefectsinthematerialisconfinedtothetensilesurfaceintheregion ofthehigheststressand,becausearelativelysmallvolumeofmaterialisinvolved,thetest resultstypicallyexhibitlessdatascatter.(adams,2008)examplesofflexuraltestconfigurations geometryandloadingofthetestconfigurationmustbesuchthatacalculablestressstate 25

32 prevailsatthesectionwherefractureoccurssothatthefracturestresscanreadilybecalculated fromthefractureload.(stanley,2001) Intheconcentricringconfiguration,thediscisuniformlysupportedonaconcentriccircularring surface.again,thevalueofthetensilefracturestressobtainedfromthistestisnottobeseen (Stanley,2001) 2.4. VibrioCholeraeattenuationbyCeramicWaterFilters Althoughtypicallyabsentfromwealthycountries,theglobalimpactofcholeraremains significant.theworldiscurrentlyexperiencingits7 th cholerapandemicandhasbeensince 1961.Withunstablerefugeeandinternallydisplacedpersonssituations,naturaldisasters,and lackofcleanwaterandsanitationinmanypartsoftheworld,thediseasehasreachedepidemic proportionsonsixcontinents.(colwell,2000)in2006,52countriesofficiallyreportedtothe WHOatotalof236,896choleracasesincluding6,311deaths,howeverthesenumbersdonot reflectthetrueburdenofcholeraduetolimitationsinthesurveillanceandnotificationsystems ofmanycountrieswherethediseaseisendemicaswellaswidespreadunderreportingdueto areactuallythreetofivemillioncholeracasesannuallycausing100,000to120,000deaths. 26

33 CholeraisanacuteintestinaldiseasecausedbythebacteriumVibrio*cholerae*O1orO139*(the twopathogenicstrainsareabbreviatedtogetheras VC ).VCexistasnaturalinhabitantsof aquaticecosystems,thusmakingthemfacultativehumanpathogens.(lobitzetal.,2000;reidl andklose,2002)thequantitiesofvcsuspendedinwateraregenerallylow(<50cfu/lforo1); howevervcmultipliesrapidlyinpoorlystoreddrinkingwaterandmaybefoundinlarge numbersattachedtoaquaticspeciessuchascyanobacteria,algae,zooplankton,and27articular (upto10 5 VCorganismsmeasuredattachedtotheirsurfaces).Thereexistsacorrelation betweencholeraoutbreaksandalgalblooms.(huqetal.,1996;reidlandklose,2002)the prevalenceofvchistoricallyispartlyduetoitsabilitytore@emergewithsignificantgenetic variation,givingrisetonewclonessuchas01eltorin1994ando139in1995and2002. (Gubala,2006)Itcausesdiseasebycolonizing,proliferatingandsecretingtoxinsintheintestine oftheinfectedperson.(wangetal.,2010)thistoxincauseswaterydiarrheaofsuchexceptional volumethathypotensiveshock(abnormallylowbloodpressure)anddeathcanoccurwithin12 hoursofthefirstsymptom.passageofvcthroughthehumangastrointestinaltractinducesa hyperinfectiousstatethatisperpetuatedevenafterbeingflushedintonaturalaquaticreservoirs forupto24hours.eradicationofcholeraisunlikelybecauseithasenvironmentalreservoirsthat willprobablycontinuetocausesporadiccasesforanindefiniteperiod.thetoxigenico1and O139strainssurviveinwaterbyenteringintoarestingstateknownas viablebutnot culturable (VNBC).CellsintheVBNCstatecanretaintheirviabilityandinfectivepotentialinthe environmentoverayearwhilealsomaintainingtheirassociatedpathogenicgenesalongwith theintegrityoftheirchromosomes.(chomvarinetal.,2007) 27

34 CausesandSymptoms Commonsourcesofinfectionincludecontaminateddrinkingwater,ice,orfood.Drinkingwater thathasbeencontaminatedatitssource(ex.byfecallycontaminatedsurfacewaterenteringan incompletelysealedwell)orduringstorage(ex.bycontactwithhandssoiledbyfeces),andice madefromcontaminatedwateraretypicalsourcesofinfection.anothermajorsourceisfood contaminatedduringorafterpreparation.(who,1994)seafood(particularlyshellfishtaken fromcontaminatedwaterandeatenraworinsufficientlycooked),andfruitandvegetables frombucketsandouthouses,sometimesusedasmanure),irrigatedwithwatercontaining humanwaste,orfreshenedwithcontaminatedwater,andtheneatenraw.(usfda,2001) VC*infectionresultsfromingestionoftheorganism.Dependingonthevulnerabilityofthe personwhohasbeenexposed,theincubationperiodforvc*infectioncanrangefrom12to72 hours.(naidooandpatric,2002)thesmallintestineistheprimarysiteofinfectionwithvcand isthesourceofthesecretorydiarrhoeaduringcholera.inpatientswithseverevcinfection,the volumeofsmallintestinefluidreachingthecolonfarexceedsthemaximumresorptivecapacity ofthecolon,whichissixlitresaday.thiscausestheprofusewaterydiarrheathat 28articular28ticholera.(Cashetal.,1974)Choleraisadiseasethatdoesnotdiscriminateonceit infiltratesaparticulararea.duringcholeraoutbreaksinnewlyaffectedareas,peopleofallages maycontractthedisease,however,choleraisamoreseverediseaseinpregnantwomen causinghighratesoffetallosseveninwomenwhoreceiveadequaterehydration.(bennish, 1994) 28

35 Inmorethan90%ofcases,choleraismild.PersonswhohaveingestedVCmayhaveno symptomsoronlymilddiarrhea.wherecholeraispresentbutnotepidemic(awidespread occurrenceinacommunityataparticulartime),itcausesfewerthan5%ofallcasesofacute diarrhea.(swerdlowandisaacson,1994)themostdistinctivefeaturesofcholeraarethe productionofavoluminouswaterystool.inpatientswithhighpurgingrates,thestoolinitially containsfaecalmatter,butquicklybecomeswhiteandopalescentwithafishyodour(commonly referredtoasricewater).vomitingcommonlyaccompaniesthediarrhoea,especiallyearlyin theillness.(naidooandpatric,2002)thispurgingcausesseveredehydrationinpatients recognizableby:anincreaseinpulserateandadecreaseinpulsevolume;hypotension;an increaseinrespiratoryrate;sunkeneyesandcheeks;drymucousmembranes;decreaseinskin turgor;adecreaseinurineoutput;lethargy;weakness;irritability;andthirst.someofthese symptomsarealsoobservedinmalnourishedchildren(decreasedskinturgor,sunkeneyes, lethargy)makingdiagnosisofdehydrationsometimesunreliableinpoorareas.(bennish,1994) Newer,rapiddiagnosticmethodsbasedondetectionofbacterialantigensorcholeratoxinin stoolsamplesarecurrentlybeingdevelopedandused.(gubala,2006;chomvarinetal.,2007) Themostimportanttreatmentofcholeraisrehydrationeitherintravenouslyororallyand consistsofpromptreplacementofthewaterandelectrolyteslostthroughtheseverediarrhea andvomiting.whenfluidsareadministeredearlyinthecourseofillness,theycanprevent dehydrationfromoccurring.whenadministeredlaterintheillness,afterdehydrationhas developed,theyareessentialforrestoringfluidbalanceandpreventingdeath.(naidooand Patric,2002)Insomecasesaneffectiveantibioticcanreducethevolumeofdiarrhoeain patientswithseverecholera,andshortentheperiodduringwhichvcisexcreted.inaddition,it 29

36 willusuallystopthediarrheawithin48hours,thusshorteningtheperiodof30articular30tion. (Rahmanetal.,1988)Antimicrobialtherapycanusuallyreducethelengthofthediarrhoeafrom aboutfourtosixdays(withouttherapy)toabouttwotothreedays.forinexpensive antimicrobialagents,thistypeoftherapycanbeextremelycosteffectiveasitreducesthe durationofhospitalstay,andreducesthevolumeofintravenousandoralfluidsrequiredfor hydration.(naidooandpatric,2002) PreventionandControlMeasures Newoutbreaksofcholeracanoccursporadicallyinanypartoftheworldwherewatersupplies, sanitation,foodsafetyandhygienepracticesareinadequate.theinhabitantsofoverpopulated communitieswithpoorsanitationandcontaminateddrinkingwatersuppliesaremost frequentlyaffected.floods,earthquakesoranydisastersinpoorcountriesoftheworldare predisposedtocholeraoutbreaks.theonlysuremeansofprotectionagainstcholeraepidemics areadequatewatersuppliesandsanitation.(naidooandpatric,2002)accordingtothewho (1994),thereisnosubstitutefordrinkingonlypotablewater,practicinggoodpersonalhygiene, andpreparingfoodsafely.accesstopotablewaterisabasicrequirementforhealth,especially intimeswhencholerathreatens.sincecontaminatedwaterisacommonsourceofcholera infection,alleffortsmustbemadetoprovidepotabledrinkingwater,aswellaswaterfreefrom pathogensforfoodpreparationandbathing.aspreviouslydescribedinsection2.1,potable waterisnotalwaysreadilyaccessibleandtreatmentmustbedoneatthepoulevelbyboiling, disinfecting,filtering,etc.goodsanitationcanmarkedlyreducetheriskoftransmissionof intestinalpathogens,includingvc,especiallywherelackofgoodsanitationmayleadto contaminationofcleanwatersourcesandfood.highpriorityshouldbegiventoobservingthe 30

37 basicprinciplesofsanitaryhumanwastedisposal,aswellasensuringtheavailabilityofpotable watersupplies.appropriatefacilitiesforhumanwastedisposalareabasicneedofall communities;intheabsenceofsuchfacilitiesthereisahighriskofcholera.(naidooandpatric, 2002) Choleravaccinationshaverecentlybeendevelopedandareconsideredamongthetoolsto preventcholerainpopulationsbelievedtobeatriskofacholeraepidemicwithinsixmonths, limitedto,refugeesandurbanslumresidents.however,vaccinationsshouldbeundertakenonly inconcertwithothercholerapreventionandcontrolmeasures.(naidooandpatric,2002) RemovalofVibrioCholeraefromDrinkingWater Asoneofthemainpreventionmeasuresforcholeraistheadequatesupplyofpotabledrinking water,investigatingtechnologiesormethodstoremovevcfromdrinkingwaterishighly relevant.afewstudieshavebeencompletedtodeterminepossibleattenuationmethodsforvc. BasedonthediscoverythatVCisfrequentlyassociatedwithzooplankton,astudy(Colwellet al.,2002)wasconductedusingasimplefiltrationmethodinvolvingasariclothfoldedfourto eighttimes.thissimplefilteriscapableofremovingzooplanktonandparticulates>20μm, effectivelyachieving99%removal(2log)ofvc.thestudywascompletedin65ruralvillagesin Bangladeshinvolvingapproximately133,000individualsfromSeptember1999throughJuly 2002anda48%reductionincholerawasobserved. 31

38 Aseparatestudy(Berneyetal.,2006)conductedtodeterminetheefficacyofsolardisinfection (SODIS)forentericpathogensincludingVCdeterminedthatthebacteriaareverysusceptibleto SODIS.VCweremeasuredtobetheleastresistanttosunlightandthemostsusceptibletomild watertemperatures(above40 theirsimilaritiesitispostulatedthatcwfswillalsobeabletoeffectivelyremovevcfrom drinkingwater.duetosizeexclusion,cwfscaneasilyfilteroutzooplanktonfromwaterfurther addingtotheprobabilitythatvccanbeattenuatedbycwfs.additionally,ascholeraoutbreaks arecommonintimesofdisasterandemergency,cwfscouldbequicklymobilizedtohelp preventanoutbreakfromoccurring.thisconceptisfurtherdiscussedinsection TheUseofCeramicWaterFiltersinEmergencyResponse Adisasterisdefinedasaseriousdisruptionaffectingacommunityorpopulationcausingdeaths, injuries,ordamagetoproperty,livelihoods,ortheenvironmentandthatexceedstheabilityof theaffectedcommunitytocopeusingitsownresources.naturaldisastersincludeearthquakes, floods,windstorms,famine,droughts,epidemics,massdisplacementofpeople,andconflicts. (Iain2010)Aspopulationdensitieshaveexpandedandthenumbersofpeoplelivinginareas pronetonaturaldisasterhavemultiplied,theimpactofdisastershasincreased.(aghababian 32

39 andteuscher,1992)additionally,climatechangeandenvironmentaldegradationarechanging Whiledisastersthreateneveryone,inpractice,theyproportionallyhurtpoorcountriesmore relativelysmallincreasesinlifethreateninginfectiousdiseasesafternaturaldisasters.in typhoid,acuterespiratoryinfectionsandleptospirosisafterdisastersarenotinfrequent.(ivers theexposurebut81%ofthemortality.(iain,2010) Theavailableliteratureondisastersindicatesthatepidemicsofcommunicablediseasesdonot alwaysoccurafternaturaldisasters.iftheydooccur,itisusuallynotthenaturaldisasteritself butthesecondaryeffectsofdisasters,suchasdestructionofwater,sanitationandhealthcare services,overcrowdingandpopulationdisplacementintoartificial,crowdedcommunitiesthat al.,2007)naturaldisasters(regardlessoftype)thatdonotresultinpopulationdisplacementare rarelyassociatedwithoutbreaks.(watsonetal.,2007) Displacedpopulationsincampsettingsareathighriskofinfectiousdiseasesduetothe secondaryeffectsofdisastersmentionedabove.deathratesofover60timesthebaselinehave 33

40 refugeesettingsarediarrhoealdiseases,respiratoryinfections,measles,meningitisand, dependingonthecountry,malaria.hiv/aidsandtuberculosisarealsobecomingincreasingly mortalityindisasters.incampsituations,diarrhoealdiseaseshaveaccountedformorethan40% ofthesedeathsintheacutephaseofanemergency,withover80%ofthesedeathsoccurringin Outbreakinvestigationshaveshownthatcommonsourcesofinfectionsincludepollutedwater sources(byfaecalcontaminationofsurfacewaterenteringincompletelysealedwells), contaminationofwaterduringtransportandstorage(throughcontactwithhandssoiledby faeces),sharedwatercontainersandcookingpots,scarcityofsoapandcontaminatedfoods. understandingofpersonalanddomestichygiene,nutritionaldeficiency,andoverallpoor sanitationarethemajorcontributingfactorsforthespreadofdiarrhealdiseases.(duet al.,2010) Potabledrinkingwaterisanimmediatepriorityinemergencies.Whennormalwatersupplies areinterruptedorcompromisedduetonaturaldisasters,complexemergenciesoroutbreaks, affectedpopulationsareoftenencouragedtoboilordisinfecttheirdrinkingwatertoensureits microbiologicalintegrity.recently,pouwatertreatmenttechnologiesverifiedinthe 34

41 developmentcontexthavebeenrecommendedforuseinemergenciessuchassodium hypochlorite,flocculant/disinfectionpowder,sodis,cwfandbiosandfiltration.these technologiesmaybeespeciallyeffectiveduringtheinitialphaseofanemergencywhen Clasen,2009)However,themajorityofresearchonPOUtechnologieshasoccurredinthe developmentcontext,andnottheemergencycontext.differencesbetweenthesetwocontexts mayimpacttheeffectivenessofpoutechnologiesinemergencyresponse. CWFhavebeenshowntobeeffectiveinthedevelopmentcontext;however,theyhavenotbeen widelyevaluatedinemergencies.threearticlesdescribingcwfinterventionsinemergencies werereviewedincludingareportfromfromthedominicanrepublicafterfloodingin2003 (Clasen,2006a),fromHaitiafterfloodingin2003(Caens,2005)andfromSriLankaafterthe tsunamiin2004(palmer,2005).additionally,adocumentsummarizingthebestpractices (Lantagne,2006a)wasalsoreviewed.Thefollowingsummarizesthemainlessonslearnedfrom theseinterventionsaswellasinterventionsofotherpoutechnologiesthatareapplicable. 1) CWFcanbeaneffectiveinterventioninsomeemergenciestoimprovewaterquality CWFhavebeenshowntobeeffectiveatimprovingwaterqualityandreducingthe incidenceofdiarrhealdisease.themicrobiologicalimprovementofwaterdocumented inthedominicanrepublicinterventionsuggeststhattheseimprovementscanalsobe 35

42 2) CWFshouldonlybeusedinanappropriateemergencysituation CWFappeartobemoreeffectiveaftertheacuteemergencyhaspassedwhenrecipients aremovingfromtransitionaltomorepermanentlivingstructures.asenseof permanencyallowsformoretimeandreceptivitytotrainingontheoperationand maintenanceofthefilters.inthesrilankatsunamiintervention,lackoflivingspacewas identifiedasabarriertotheiruse,andrecipientslivinginanemergencysheltertypewas associatedwithhavingagreaternumberofproblemswiththefilter.(palmer,2005) Additionally,CWFinterventionsshouldbetargetedtocontextsmostatriskof waterbornediseasebasedonemergencytypeandstage,locationandsituation. (LantagneandClasen,2009) 3) UserpreferenceshouldbeconsideredwhendecidingwhatPOUtechnologyto implement Asuseracceptanceandtraininghavebeenidentifiedasthemostdifficultfactorsin implementationitisanticipatedthatifuserpreferencewereconsideredintheoption selectiondecisionthatuseracceptabilityofthechosenproductwouldincrease. (LantagneandClasen,2009) 4) Trainingiscrucialforproperusageandmaintenance Inthedevelopmentcontext,higherlevelsofuseradoptionhavebeendocumented whenpoutechnologiesarepromotedinschoolsorhealthclinicsandwhenmotivational interviewingandsocialmarketingareemployedasbehaviourchangecommunications strategies.(lantagneandclasen,2009)whileitcanbemoredifficulttoconductin 36

43 emergencies,trainingisanecessarycomponentoftheemergencyimplementation strategy.trainingwasidentifiedasafactorcontributingtothehigherusageofcwfin boththesrilankatsunamianddominicanrepublicfloodinginterventions.althoughthe usage,sometrainingattheoutsetonoperationandmaintenanceofthefilterswas identifiedas vital.(palmer,2005;clasen,2006a)itshouldbenotedthatallrecipients mustbeprovidedwithallthematerialsnecessarytouseandmaintainthecwf includingthefilterelement,plasticreceptacle,brushforcleaningtheelement,etc.in thedevelopmentcontext,pouwatertreatmenttechnologyinterventionsselect culturallyappropriateoptions,distributetheproductsreliablyandworkwithtrusted localcommunityeducatorstoencouragehealthywaterpractices.itappearsasifthese factorstranslateintotheemergencycontextanditisrecommendedthatmaterialsbe developedspecificallyfortheemergencycontexttoassistorganizationsinconducting thetrainingnecessarytoensureprojectsuccess.(lantagneandclasen,2009) 5) communitieswherecwfweredistributed,itwasfoundthatinonesrilankantsunami responsecommunity,23%ofpeoplewereusingtheceramicfilterthreemonthsafter distribution,inthedominicanrepublic,48.7%ofhouseholdshadcorrectlyoperating filters16monthsafterdistributionwith54%ofwatersamplesfromoperatingfilters (26.1%oftotal)freeofthermotolerantcoliform.(Palmer,2005;Clasen,2006a)InHaiti, 37

44 usersexpressedadesiretocontinueusingthefilter.(caens,2005)thesestudies 6) Adequateproductstocksarenecessaryforemergencyresponse TheabilitytoobtainanddistributeCWFiscriticaltointerventionsuccessin emergencies.additionally,theimportanceofaccesstoreplacementcwfpartsfor andthetypeofemergencyandthereforemaybeconsideredeitherunimportantor vital.intheinstanceswherethegoalistoprovideemergencyreliefthattranslatesinto necessaryforthesustainabilityofsuchaproject.ithasalreadybeenshownthatthe CWFshouldonlybeimplementedifthenecessarymaterialstomanufacture replacementpartsarelocallyorreadilyavailable.abenefitofproductsthatarelocally availablepriortoemergenciesisthat,ifadequatestocksaremaintained,thefilterscan bedeployedquicklyandefficiently.pottersforpeacehasestablished17cwf manufacturingfacilitiesworldwideandhasidentifiedfourkeyelementstofacility successincluding:thepartnerngo sexperiencewithmarketingandhealthtosupport thefilterproductionwithfilterdistribution,traininganddemandcreation;the availabilityoftechnicalsupportandamountofincountryvisitsbypottersforpeace;the understandingoflocalsituationsthatimpactthefilterfacilityincludingcountrystability; 38

45 andthathavingasustainablemarketingplanismorecriticalthanstartingwithinitial funding.(lantagne,2006a) Ingeneral,implementersofPOUwatertreatmenttechnologiesinemergenciesshouldconsider thatintroducinganuntestedtechnologyinanemergencyaddscomplicationstothe interventionthatmayreduceeffectiveness,sometechnologiesmaybemoreappropriatein particularemergenciesthanothers,pouwatertreatmenttechnologiesshouldbeonestrategy ofmanytoensurepotabledrinkingwateraccessatdifferentstagesoftheemergencyandthe thetechnologyshouldbeconsideredwhileprojectplanning.(lantagneandclasen,2009)cwf areaproventechnologythat,incertaincontexts,willbeeffectiveinprovidingapotable drinkingwatersourceduringemergencies References Adams,D.(2008).Flexural*testing*of*fiber?reinforced*ceramics.*High*Performance*Composites. Aghababian,RVandTeuscher,J.(1992).Infectious*diseases*following*major*disasters.Annalsof ASTMC1337.(2000).Standard*Test*Method*for*Creep*and*Creep*Rupture*of*Continuous*Fiber? Reinforced*Ceramic*Composites*under*Tensile*Loading*at*Elevated*Temperatures.ASTM International.WestConshohocken,Pennsylvania,UnitedStates. ASTMD3878.(2007).Standard*Terminology*for*Composite*Materials.ASTMInternational.West Conshohocken,Pennsylvania,UnitedStates. Bennish,ML.(1994).Cholera:*pathophysiology,*clinical*features,*and*treatment.*Vibrio*cholerae* 39

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47 Chomvarin,C.,Namwat,W.,Wongwajana,S.,andAlam,M.(2007).Application*of*duplex?PCR*in* rapid*and*reliable*detection*of*toxigenic*vibrio*cholerae*in*water*samples*in*thailand.journal Clasen,T.,andBoisson,S.(2006).Household?based*ceramic*water*filters*for*the*treatment*of* drinking*water*in*disaster*response:*an*assessment*of*a*pilot*programme*in*the*dominican* Clasen,T.,andBastable,A.(2003).Faecal*contamination*of*drinking*water*during*collection*and* household*storage:*the*need*to*extend*protection*to*the*point*of*use.journalofwaterand Clasen,T.,Brown,J.,Collin,S.,Suntura,O.,andCairncross,S.(2004).Reducing*diarrhea*through* the*use*of*household?based*ceramic*water*filters:*a*randomized,*controlled*trial*in*rural* Clasen,T.,Schmidt,W.,Rabie,T.,Roberts,I.,andCairncross,S.(2007).Interventions*to*improve* water*quality*for*preventing*diarrhoea:*systematic*review*and*meta?analysis.bmj.com, 334(7597),782. Colwell,R.(2000).Viable*but*nonculturable*bacteria:*A*survival*strategy.JournalofInfectionand Colwell,R,Huq,A.,Islam,M.,Aziz,K.,Yunus,M.,Khan,N.,Mahmud,A.,Sack,R,Nair,G., Curtis,V.,Cairncross,S.,andYonli,R.(2000).Domestic*hygiene*and*diarrhoea* pinpointing*the* Deen,J.,Seidlein,L.,Sur,D.,Agtini,M.,Lucas,M.,Lopez,A.,Kim,D.,Ali,M.,andClemens,J. (2008).The*High*Burden*of*Cholera*in*Children:*Comparison*of*Incidence*from*Endemic*Areas* Dies,R.(2003).Development*of*a*ceramic*water*filter*for*Nepal.MasterofEngineeringthesis: themassachusettsinstituteoftechnology,departmentofcivilandenvironmental Engineering. Donald,I.,andMcMillan,P.(1976).Ceramic?matrix*composites.JournalofMaterialsScienceII. 41

48 Doocy,S.,andBurnham,G.(2006).Point?of?use*water*treatment*and*diarrhoea*reduction*in*the* emergency*context:*an*effectiveness*trial*in*liberia.tropicalmedicineandinternational Du,W.,FitzGerald,G.,Clark,M.,andHou,X.(2010).Health*Impacts*of*Floods.Prehospital Duke,W.,Nordin,R.,andMazumder,A.(2006b).Comparative*Analysis*of*the*Filtrón*and* Biosand*Water*Filters.Monographavailablefromhttp:// Goto,K.andKagawa,Y.(1994).Crack?fiber*interaction*and*interfacial*failure*models*in*fiber? Gubala,A.(2006).Multiplex*real?time*PCR*detection*of*Vibrio*cholerae.Journalof Handa,S.(2010).Cholera. Howard,M.,Brillman,J.,andBurkle,F.(1996).Infectious*Disease*Emergencies*in*Disasters. Huq,A.,Xu,B.,Chowdhury,M.,Islam,M.,Montilla,R.,andColwell,R.(1996).A*Simple*Filtration* Method*to*Remove*Plankton?Associated*Vibrio*Cholerae*in*Raw*Water*Supplies*in*Developing* HygieneImprovementProject(HIP).(2006).Summary*of*Household*Water*Treatment*and* Storage*E?Conference*Proceedings.WashingtonDC:HIP. Iain,B(2010).Defending*Against*Disasters:*Global*Public*Health*Emergencies*and*Opportunities* 228S. IRC(InternationalWaterandSanitationCentre,Delft).(2005).Household*water*treatment*FAQs. Delft:IRC. Ivers,L.,andRyan,E.(2006).Infectious*diseases*of*severe*weather?related*and*flood?related* Jagals,P.,Jagals,C.,andBokako,T.(2003).The*effect*of*container?biofilm*on*the*microbiological* quality*of*water*used*from*plastic*household*containers.journalofwaterandhealth. Nanoparticles*for*Point?of?Use*Water*Treatment*in*Rural*Guatemala.Journalof 42

49 Kosek,M.,Bern,C.,andGuerrant,R.(2003).The*global*burden*of*diarrhoeal*disease,*as* estimated*from*studies*published*between*1992*and*2000.bulletinoftheworldhealth Organization.81(3):197. KuntzM.,Meier,B.,andGrathwohl,G.(1993).Residual*Stresses*in*Fiber?Reinforced*Ceramics* Lantagne,D.(2001a).Investigations*of*the*Potters*for*Peace*Colloidal*Silver*Impregnated* Ceramic*Filter.*Report*1:*Intrinsic*Effectiveness.AlethiaEnvironmental,Allston,MA,USA. Availablefromauthors. Lantagne,D.(2001b).Investigations*of*the*Potters*for*Peace*Colloidal*Silver*Impregnated* Ceramic*Filter.*Report*2:*Field*Investigations.AlethiaEnvironmental,Allston,MA,USA. Availablefromauthors. Lantagne,D.(2006a).Potters*for*Peace:*Filter*Production*Facility*Best*Practices.Pottersfor Peace,Managua,Nicaragua.Availablefromauthors. Lantagne,D.,andClasen,T.(2009).Point*of*Use*Water*Treatment*in*Emergency*Response.* LondonSchoolofHygieneandTropicalMedicine.London,UK. Lantagne,D.,Quick,R.,andMintz,E.(2006).Household*water*treatment*and*safe*storage* options*in*developing*countries:*a*review*of*current*implementation*practices.washington DC:WoodrowWilsonInternationalCenter. Lantagne,D.,Klarman,M.,Mayer,A.,Preston,K.,Napotnik,J.,andJellison,K.(2010).Effect*of* production*variables*on*microbiological*removal*in*locally?produced*ceramic*filters*for* household*water*treatment.internationaljournalofenvironmentalhealthresearch. Lobitz,B.,Beck,L.,Huq,A.,Wood,B.,Fuchs,G.,Faruque,A.,andColwell,R.(2000).Climate*and* infectious*disease:*use*of*remote*sensing*for*detection*of*vibrio*cholerae*by*indirect* Lopez,A.,Mathers,C.,Ezzati,M.,Jamison,D.,andMurray,C.(2006).Global*burden*of*disease* and*risk*factors.newyork,newyork:theworldbankandoxforduniversitypress. Mackenbach,J.(2007).Sanitation:*pragmatism*works.BritishMedicalJournal.334(7583):17. Macy,J.,andQuick,R.(2002).World*spotlight:*the*Safe*Water*System* *a*household*based* water*quality*intervention*program*for*the*developing*world.waterconditioningand PurificationMagazine.44(4). 43

50 44 Marshall,D.,andEvans,A.(1985).Failure*Mechanisms*in*Ceramic?Fiber/Ceramic?Matrix* Mattelet,C.(2006).Household*Ceramic*Water*Filter*Evaluation*Using*Three*Simple*Low?Cost* Methods:*Membrane*Filtration,*3M*Petrifilm,*and*Hydrogen*Sulfide*Bacteria*in*Northern* Region,*Ghana.MITMaster sthesis:departmentofcivilandenvironmentalengineering. Mong,Y.,Kaiser,R.,Ibrahim,D.,Rasoatiana,Razafimbololona,L.,andQuick,R.(2001).Impact*of* the*safe*water*system*on*water*quality*in*cyclone?affected*communities*in*madagascar. Murphy,H.,Sampson,M.,McBean,E.,andFarahbakhsh,K.(2009).Influence*of*household* practices*on*the*performance*of*clay*pot*water*filters*in*rural*cambodia.desalination. Murphy,H.M.(2010).A*critical*evaluation*of*the*appropriateness*of*ceramic*and*biosand*filters* in*rural*cambodia.unpublished.doctorofphilosophy,universityofguelph,guelph. Murthy,P.,Chamis,C.,andMital,S.(1996).Computational*Simulation*of*Continuous*Fiber? Reinforced*Ceramic*Matrix*Composites*Behaviour.NASATechnicalPaper3602. Naidoo,A.,andPatric,K.(2002).Cholera:*a*continuous*epidemic*in*Africa.TheJournalofThe Palmer,J.(2005).Community*acceptability*of*household*ceramic*water*filters*distributed*during* Oxfam s*response*to*the*tsunami*in*sri*lanka.london,uk,londonschoolofhygieneand TropicalMedicine.MSc.Availablefromauthors. Phillips,DC.(1989).Fiber?Reinforced*Ceramics.PergamonPressplc,ConciseEncyclopediaof Rahman,O.,Bennish,M.,Alam,A.,andSalam,M.(1988).Rapid*intravenous*rehydration*by* means*of*a*single*polyectrolyte*solution*with*or*without*dextrose.journalofpediatrics. Reidl,J.,andKlose,K.(2002).Vibrio*Cholerae*and*cholera:*out*of*the*water*and*into*the*host.* Roberts,M.(2004).Field*test*of*a*silver?impregnated*ceramic*filter.Proceedingsofthe30 th WEDCInternationalConference,Vientiane,LaoPDR. Roberts,L.,Chartier,Y.,Chartier,O.,Malenga,G.,Toole,M.,andRodka,H.(2001).Keeping*clean* water*clean*in*a*malawi*refugee*camp:*a*randomized*intervention*trial.bulletinoftheworld

51 Simonis,J.,andBasson,A.(2011).Evaluation*of*a*low?cost*ceramic*micro?porous*filter*for* Sobsey,M.(2002).Managing*water*in*the*home:*accelerated*health*gains*from*improved*water* supply.who/sde.wsh/02.07,worldhealthorganization(who),geneva,switzerland. Sobsey,M.(2006).Drinking*water*and*health*research:*a*look*to*the*future*in*the*United*States* Souter,P.,Cruickshank,G.,Tankerville,M.,Keswick,B.,Ellis,B.,Langworthy,D.,Metz,K., Appleby,M.,Hamilton,N.,Jones,A.,andPerry,J.(2003).Evaluation*of*a*new*water* treatment*for*point?of?use*household*applications*to*remove*microorganisms*and*arsenic* Smith,P.,andYeomans,J.(Nodate).Benefits*of*Fiber*and*Particulate*Reinforcement.Materials andscienceengineering VolII.EncyclopediaofLifeSupportSystems. Stanley,P.(2001).Mechanical*strength*testing*of*compacted*powders.InternationalJournalof Stauber,C.,Elliott,M.,Koksal,F.,Ortiz,G.,DiGiano,F.,andSobsey,M.(2006).Characterisation* of*the*biosand*filter*for*e.*coli*reductions*from*household*drinking*water*under*controlled* SwerdlowD.,andIsaacson,M.(1994).The*epidemiology*of*cholera*in*Africa.Vibriocholeraeand Thompson,T.,Sobsey,M.,andBartram,J.(2003).Providing*clean*water,*keeping*water*clean:* UnitedStatesFoodandDrugAdministration(USFDA).(2001).Foodborne*Pathogenic* Microorganisms*and*Natural*Toxins*Handbook.CenterforFoodSafetyandAppliedNutrition, USFoodandDrugAdministration. UNDP.(2006).Human*development*report*2006,*beyond*scarcity:*Power,*poverty*and*the*global* water*crisis.newyork,newyork:unitednationsdevelopmentprogramme. UNICEFandWHO.(2012).Progress*on*Drinking*Water*and*Sanitation:*2012*Update.NewYork, NewYork:UNICEF. VanHalem,D.(2006).Ceramic*silver*impregnated*pot*filters*for*household*drinking*water* treatment*in*developing*countries.master sthesis,facultyofcivilengineering.delft UniversityofTechnology,Netherlands. 45

52 Wang,D.,Xu,X.,Deng,X.,andChen,C.(2010).Detection*of*Vibrio*cholerae*O1*and*O139*in* Environmental*Water*Samples*by*Immunofluorescent?Aggregation*Assay.Appliedand Watson,J.,Gayer,M.,andConnolly,M.(2007).Epidemics*after*Natural*Disasters.Emerging WorldHealthOrganization(WHO).(1994).GuidelinesforCholeraControl.Geneva:WorldHealth Organization. WorldHealthOrganization(WHO).(2005).Household*water*treatment*and*safe*storage* following*emergencies*and*disasters.geneva:worldhealthorganization. WorldHealthOrganization(WHO).(2006).WHO*Guidelines*for*Drinking*Water*Quality,*3 rd * edition.geneva:worldhealthorganization.availableonlineathttp:// WorldHealthOrganization(WHO).(2007).Combatingwaterbornediseaseatthehousehold level.geneva:worldhealthorganization. Wright,J.,Gundry,S.,andConroy,R.(2004).Household*drinking*water*in*developing*countries:* A*systematic*review*of*microbiological*contamination*between*source*and*point?of?use. TropicalMedicineandInternationalHealth.9(1):106@117. Zaritsky,A.,andWoldringh,C.(1978).Chromosome*replication*rate*and*cell*shape*in*Escherichia* coli:*lack*of*coupling.journalofbacteriology.135(2):581@

53 ChapterThree: StudyDesignandMethods 47

54 3. StudyDesignandMethods 3.1. CeramicWaterFilterDiscDesign TherecipeusedforcreatingtheCWFdiscswasmodeledafterthatusedbyResource DevelopmentInternational Cambodia(RDIC).(Haganetal.,2008)Atotalofsevendesign scenarioswerecreatedbyvaryingboththeamountofcarbonfibreaddedtotherecipeaswell RicehullswereobtainedfromTheCanadianWildRiceMercantileofThunderBay,Ontarioand carbonfibrewasobtainedfrombarrday,inc.ofcambridge,ontario.aspecificationsheetfor thecarbonfibreisincludedinappendixa.theclayusedwasepkkaolincontainingahigh amountofkaolinite(approximately97%,chemicalcomposition:al 2 Si 2 O 5 (OH) 4 )obtainedfrom Tucker spotterysupplies,inc.ofrichmondhill,ontario. Table3W1 CWFDiscDesignScenarios Material Disc1 Disc2 Disc3 Disc4 Disc5 Disc6 Disc7 EPKClay 1200g 1191g 1191g 1188g 1188g 1194g 1194g MilledRice Husks 355.5g 355.5g 355.5g 355.5g 355.5g 355.5g 355.5g Water (48approx.) 750mL 750mL 750mL 750mL 750mL 750mL 750mL Carbon Fibre None 9g 9g 12g 12g 6g 6g Carbon FibreLength None 6cm 3cm 6cm 3cm 6cm 3cm Thecarbonfibrewasvariedbyweight(0%,0.5%,0.76%and1%ofclayweight)andbylength(3 cmand6cmindividualfibrelengths).thericehullsweremilledusinganikamf10grinderwith a1mmscreen(figure3@1).priortomixingthericehullsweresievedusingano.16(1.19mm mesh)sieve. 48

55 Figure3W1:RiceHullsbeforemilling(left)andafter(right) Clay,ricehullsandcarbonfibrewerecombinedinacontainerandmixedthoroughlyforfive looselywiththeclayandriceratherthanplacedinagridinordertoreplicatehowitwouldmost element.thewaterwasthenquicklyandevenlyaddedandthemixturewaskneadedforatleast 20minutes.Thesidesofthecontainerwereoccasionallyscrapedtoensurealltheingredients weremixedinthoroughly.oncemixed,approximately660gwereweighedandroughlyhand pressedintoadiscshape. 49

56 Figure3W2:Themixeddryingredientsbeforewaterisadded Thediscmoldwasplacedontoaflatsurfaceandlinedwithathinplasticbagtopreventtheclay mixturefromsticking.theclayballwasaddedtothemoldandthenthetopofthemoldwas pressedfirmlydownformingthediscshape.onceformed,thediscswereremovedfromthe moldandallowedtoairdryforthreetofourhours.afterthistime,thesurfacesofthediscs werescrapedusingaplasticputtyknifetoremoveirregularitiesandsmooththesurfaces. 50

57 Figure3W3:DiscsairWdryingpriortofiring fibresarenotunidirectionalandstraightbutrathercrimpedandbentwithintheclaymatrix. Cfortwo hoursandthenincreasedforeighttotenhoursto866 C.Thetemperaturewasheldatthis temperatureforninehoursandthenallowedtocoolfor24hours.oncefired,a0.55%solution thediscscameoutofthefurnacewithblackcarbonstainsasaresultofthericehullsburning manufactured.theaveragediscdiameteris155mm±1.6mmandthickness17.86mm±0.62 mm.theaveragediscweightafterfiringis300g±11.3g.accordingtoastmstandard 51

58 Figure3W4:Mufflefurnaceusedforfiringdiscs Figure3W5:Discsafterfiring 3.2. FlowRateTesting Inordertotestthediscs,anapparatuswasdesignedtoallowflowofwaterthroughthem.Each throughthering.oncethediscswerefastenedintotheirringstheyhadaneffectivesurface 52

59 areaof120mm±3.2mm.threeapparatusesweremanufacturedfrompvcpipetoallowfor Figure3W6:ApparatusfortestingCWFdiscs Theflowtestwasconductedbyfirstinstallingthediscsintotheapparatuses.3Loftapwaterat approximatelyroomtemperaturewasaddedintothetopofeachapparatusandwaterwas allowedtoflowthroughfor30mintoensureeachdiscwasfullysaturated.theeffluentfrom eachapparatuswascollectedinlargeerlenmeyerflasks.attheendofthe30minthewaterwas toppedupto3landtheflowteststarted.after3hrtheeffluentvolumewasrecorded. 53

60 Figure3W7:FlowtestapparatussetWup 3.3. BacteriaAttenuationTesting Tobegin,threediscswererandomlyselectedtobetestedsothatdiscsofthesamedesign scenariowerenottestedatthesametime.priortotesting,eachoftheapparatusesandthe discstobetestedwerecleanedwitha1:10dilutionofhouseholdbleach(6%sodium hypochlorite)andthoroughlyrinsedwithdechlorinatedtapwater.therinsingbothremovedthe chlorineasevidencedbyameasuredchlorineconcentrationof0mg/lintheeffluentandserved effluentoftherinsewatermeasuredchlorineresidual,sodiumthiosulphatewasaddedtothe rinsewaterandallowedtoflowthroughfortenminutesatwhichpointtheeffluentwas 54

61 retestedforchlorine.ifthechlorineconcentrationmeasured0mg/l,aneffluentsamplefrom contaminationpriortoinitiatingtheexperiments. forbacterialpathogenspotentiallypresentindrinkingwatersources.ecoliisagramnegative, istypicalofpathogenicbacteriapresentindrinkingwatersuchaspathogenicstrainsofecoli, Salmonella,Shigella,CampylobacterandVibrio.Thisparticularstrainwasusedduetoitsrelative easeofproductioninthelaboratory. Ecoliwasculturedinautoclavedtrypticsoybroth(TSB)byadding0.1mLofEcolistockto10mL ofpreparedtsbinasteriletesttube.thetsbmediumwas15gtrypticsoybrothper500ml dechlorinatedtapwatertoserveastheinfluentspikewater.toensureacompletetransferof theculturetothespikewater,thetesttubewasrinsedthreetimesintothespikewaterwith concentrationsrangedfrom CFU/100mL(averageof1.14x10 8 CFU/100mL).This bacterialconcentrationishigherthantypicallevelsmeasuredinsurfacewaterusedfordrinking water,toensurethattherewouldbemeasureableconcentrationsintheeffluenttoenable percentremovalcalculations.approximately2.5loftheinfluentspikewaterwasaddedtoeach apparatusandthespikewaterwasallowedtoflowthroughthediscsfor30minutespriorto 55

62 startingthetesttoensureeachdiscwasfullysaturated.afterthe30minutes,200mlof effluentwascollectedinanautoclavedflaskfromeachdisc.if200mlwasstillnotcollected after60minutes,theexistingamountineachflaskwasused.asecondinfluentsamplewas takenoncethethreeeffluentsampleswerecollected. ThemembranefiltrationmethodwasusedtoenumeratetheEcoliinundilutedanddiluted influentandeffluentsamples.underalaminarflowhood,serialdilutionswereperformedon thecollectedsamplestoensurethattheplateswouldbewithinthecountablerange( fortheinfluentsamplesand 10 0 fortheeffluentsamples.inordertoperformthedilutions,9mlofautoclavedmilli@q waterwasaddedtosteriletesttubes.thecollectedsamplesweremixedthoroughlyandthen 10mLwasaddedtothefirsttesttubeinthedilutionseries.Twoinfluentsamplesandtwo effluentsamplesfromeachdiscweredilutedandplatedforenumeration.1mlofthe10 0 test testtubeusingafresh,disposablepipettetocreatetheinitial testtubewasthenaddedtothe testtubeandsoon,untilallthetesttubesweredilutedwith10%oftheprevioussolution. 47mmpetridisheswithsterileabsorbentpadswerelabelledforeachofthedilutionstobe plated.2mloftsbwereaddedtoeachofthedishesusingafresh,disposablepipettetoensure nocontamination.thelidsofthepetridisheswerereplacedimmediatelyafterthebrothwas added. 56

63 Figure3W8:Serialdilutionsandpetridishesforplatingsamples filteringofe.coli.usingsterilizedtweezers,thefilterpaperwasplacedonanautoclavedfilter topthatwassealedontopofa1lfilteringflask,andattachedtoanelectricvacuumpump. Next,thevacuumwasturnedonfor30seconds,andthenturnedoff.Thesamplewasspread evenlyacrossthesurfaceofthefilterpaper,withthevacuumbeingturnedonfor30seconds, ensurethepropertransferofthesampletothefilterpaper.thevacuumwasthenturnedonfor afinaltimefor30seconds,andshutoff.thefilteredsamplewasasepticallytransferredtothe Petridishusingsteriletweezers,thecoverreplaced,andthebottomofthePetridishtapped severaltimesuntilairbubbleswerefullyremoved.thefilteringandplacementwerethen repeatedforalldilutions,inverted,andplacedintheincubatoratatemperatureof37 C. 57

64 Figure3W9:MembranefiltrationlabequipmentsetWup coloniesperplate(standardmethods9222).thenumberofcolonieswasthenrecorded,while TNTCrepresentedplatesthathadcolonies TooNumerousToCount,whileNDCrepresented NoDiscernibleColonies propercleanupmethodsfollowed.intotal,twoinfluentsamples,twoeffluentsamplesfrom eachdisc,onecontrolsamplefromeachdisctocheckforbacterialcontaminationpriorto addingthespikewater,onecontrolsamplefromthetsbandonecontrolsamplefromthe replicatesoftheecoliattenuationtestingwerecompletedforeachofthe21cwfdiscs. 58

65 Figure3W10:ExampleofEcolicoloniesafterincubation(NDCright,countablecoloniescentre, andtntcleft) 3.4. EquiWbiaxialFlexuralStrengthTesting InordertocomparethestrengthoftheCWFdiscdesignscenariostodeterminetheeffectof StrengthofAdvancedCeramicsatAmbientTemperaturewasfollowedascloselyaspossible. Flexuralstrengthisamechanicalparameterforabrittlematerialdefinedasthematerial sability toresistdeformationunderload.thetestmethodusesaconcentricringtestconfiguration stressamaterialiscapableofsustainingwhensubjectedtoflexurebetweentwoconcentric rings.thediscisplacedontoalargersupportringandcompressedbyasmallerloadringas 59

66 Figure3W11:Sectionviewofbasicequipmentsetupforequibiaxialtesting(ASTM2009) TwotypesoftestspecimensareconsideredinASTMC1499, machined and 25mm.Thediscsfabricatedasdescribedabovehaveanaveragethicknessof17.86mm± 0.62mmanddonotmeetthisrequirementthereforetheresultsgeneratedmustbeusedfor comparisonpurposesonly. installedconcentricallyonaninstron5969universaltestingmachine.thesupportringhasa diameterof120mmandthicknessof5mmandtheloadringhasadiameterof60mmand thicknessof5mm.accordingtoastmc1499theratiooftheloadringdiameter,d L tothatof thesupportring,d S is0.2 D L /D S 0.5.TheratioofD L /D S forthetestingfixtureusedis0.5.the 60

67 supportringdiametershouldbewithin2 S )/h 12where D isthediscdiameterand h isthediscthickness.theratioof(d@d S )/hforthistestis2.inordertominimizetheeffectsof testspecimen@ringmisalignmentasheetofsiliconewasplacedbetweenthediscandthe supportring. Figure3W12:Loadingfixturefortheequibiaxialflexuralstrengthtesting Fiveofthefabricateddiscswerebrokenpriortobeginningthestructuraltestingthereforeonly 16discsweretested.SomeofthediscswerebrokenwhileremovingthemfromthePVCrings theyweresealedintoandsomeofthemwerebrokenwhiledeterminingwhichstructuraltestto useandunderwhatconditions.priortotestingtheremainingdiscs,thediameterandthickness ofeachweremeasuredatsixequallyspacedlocationsaroundthedisc.theloadandsupport ringswerethencleanedandinspectedforanynicksorimperfections.thesiliconeringwasthen placedontothesupportringandthediscwasplacedontoptakingcaretocenteritonthering. 61

68 Thediscwaspreloadedbyloweringthecrossheaduntiltheloadringwasjusttouchingthe surfaceofthediscandthevalueofthepreloadrecorded.thedisplacementoftheloadringwas settozeroandthetestinitiated.thedisplacementrateofthecrossheadwassetto10mm/s. Thetestwassettoendoncethedisplacementofthecrossheadreached20mmtoensurethe discwouldfailbeforetheendofthetest.thedatacollectedfromeachtestincludestime(s), extension(mm)andload(kn)atarateof13.33hz. Figure3W13:Equibiaxialflexuraltestsetup 3.5. Limitations Theprimarylimitationsofthestudywerethesmallnumberoffilterstestedforeachdesign 62

69 filtersandtheshortdurationoftestingperfilter(tworeplicatesofthebacteriaattenuation testingwerecompleted). Duetotimeandrawmateriallimitationsonlythreediscsofeachdesignscenariocouldbe fabricatedlimitingthenumberofreplicatesthatcouldbecompletedforalltests.additionally, accordingtoastmc1499,aminimumoftentestspecimensisrequiredforthepurposeof estimatingameanbiaxialflexuralstrength. Themethodofdiscfabricationresultedinsomewarpageandunevensurfaces,whichcanresult flexuralstrength.thediscsurfacesincontactwiththetestingringsshouldbeasflataspossible forsuccessfulequibiaxialtests. Thetestingofthediscswascompletedoverarelativelyshorttimeduration.Inordertobetter characterizetheimpactsofaddingcarbonfibretothestandardcwfrecipecontinuingtesting overalongertimeperiodwouldbepertinentascwfstendtoneedreplacingafteronetotwo years References ASTMC1499.(2009).Standard*Test*Method*for*Monotonic*Equibiaxial*Flexural*Strength*of* Advanced*Ceramics*at*Ambient*Temperature.ASTMInternational.WestConshohocken, Pennsylvania,UnitedStates. Hagan,J.,Harley,N.,Pointing,D.,Sampson,M.,andSoam,V.(2008).Resource*Development* International*?*Cambodia*Ceramic*Water*Filter*Handbook.PhnomPenh,Cambodia. 63

70 ChapterFour:Results 64

71 4. Results 4.1. StudyObjectives Asindicatedpreviously,CWFshavebeenshowntobeeffectiveatattenuatingpathogensfrom drinkingwaterandreducingtheincidenceofdiarrhealdisease;however,thecwfstypicallyonly lastapproximatelytwoyearsmainlyduetobreakage,eitheroftheceramicfilterelement,the spigot,orthecontainercoupledwithlimitedavailabilityofreplacementpartsincommunities. (Brown,2007)Giventhatthesefiltersaregainingmorewidespreaduseinanumberofcountries worldwide,extendingtheirlifespanofusewouldhavesignificantvalue.inanefforttoimprove thissituation,thisresearchspecificallyinvestigatesthepotentialforresiliencyofthecwf elementtobeimprovedthroughtheadditionofcarbonfibretotherecipe.thischapter summarizestheeffectsofaddingcarbonfibretolowcostcwfs,includingexaminingimpactson flowrate,ecoliattenuation,andbiaxialflexuralstrength.theobjectivesinclude: PerformingE.coliattenuationtestingontheCWFdiscstodeterminebacteriaremoval characteristics;and, 4. PerformingstructuraltestingontheCWFdiscstodeterminestrengthcharacteristics. (0%,0.5%,0.76%and1%ofclayweightwhichequatesto0g,2g,3gand4gofcarbonfibreper disc,respectively)andbylength(3cmand6cmindividualfibrelengths).theweightofcarbon fibrewasvariedtoexplorearangeofamountsinanattempttocapturetheminimumrequired 65

72 toachievethepotentialbenefitswhileensuringalowfabricationcost.thelengthsusedwere approximately20%and40%ofthediscdiameterinanattempttocharacterizetheimpactsof variedreinforcingfibrelengths. Table4W1:CWFDiscRecipes DiscType DesignScenario 1 nocarbonfibre 2 3gofcarbonfibreperdisc,6cmlengths 3 3gofcarbonfibreperdisc,3cmlengths 4 4gofcarbonfibreperdisc,6cmlengths 5 4gofcarbonfibreperdisc,3cmlengths 6 2gofcarbonfibreperdisc,6cmlengths 7 2gofcarbonfibreperdisc,3cmlengths 4.2. Results AlldatafromthecompletedtestswereenteredintoMicrosoftExcelforMac2011andanalyzed usingstandardexcelfunctions. Ecolipercentreductionwascalculatedasfollows: %Removed=[(Conc EF Conc IN )/Conc IN ]X100 Log 10 reductionvalue(lrv)wascalculatedasfollows: Where: %Removed=Ecolipercentreduction(%) Conc IN =influentconcentration(cfu/100ml) Conc EF =effluentconcentration(cfu/100ml) LRV=Log 10IN Log 10EF Where: LRV=Log 10 reductionvalue Log 10IN =Log 10 ofinfluentconcentration Log 10EF =Log 10 ofeffluentconcentration 66

73 EcoliattenuationdatawerealsoenteredintoJMP10andanalysiscompleted.Incomparing Ecoliattenuationacrossalldisctypes,ANOVAwasused.Statisticalsignificance(α=0.05)was assessedusingthestudent presentedhere;individualresultsareincludedinappendixb FlowTestData Two3hrflowtestswereconductedasdescribedinSection3.2oneachofthediscs;however, themeasuredflowratethroughallofthediscsfabricatedforeachdisctype(i.e.all21discs) increasedgreatlyatthecompletionofthefirsttwotests(theflowmeasuredintest1wasmuch lowerthantheflowmeasuredintest2).twoadditionaltests(tests3and4)wereconducted and,asthemeasuredflowratesstabilized,onlytheseresultswereretainedforcalculationand analysis.theincreaseinflowratemaybeattributabletotheflushingofbothdustfromthe 2. Test3 and Test4 refertothetwoteststhatwereconductedaftertheflowratethroughthe discsstabilized. STD referstostandarddeviationand RSD% referstorelativestandard deviation. 67

74 Table4W2:Summaryofflowtestdata Disc Apparatus Test3 Test4 Average Average TotalAverage (ml/3hr) (ml/hr) (ml/hr) STD RSD% 1A B C A B C A B C A B C A B C A B C A B C Analysis Duetothedesignofthetestingapparatus(Figure3@6),theeffectivesurfaceareaoftheCWF discswasapproximately113cm 2 withamaximumvolumeof3labletobeaddedtothetopof eachapparatus.inordertocharacterizetheimpacttheadditionofcarbonfibrehadontheflow ratescomparisonsweremadebetweentherecipewithoutcarbonfibre(disctype1)andthose withcarbonfibre(disctypes2through7). Whengenerallycomparingtheflowtestresultsofdiscswithandwithoutcarbonfibre,the resultsshowthatthecarbonfibreadditiontothediscsincreasedtheflowratebyanaverageof 595%.Theaverageflowrateofdiscswithoutcarbonfibre(DiscType1)is85mL/hrandthe 68

75 averageflowrateofdiscswithcarbonfibre(disctypes2through7)is506ml/hr.lookingat eachdisctypeindividually,theadditionofcarbonfibreincreasedtheflowratebyarangeof 424%(comparingDiscType1withDiscType7:2gofcarbonfibreat3cmlengths)to706% (comparingdisctype1withdisctype5:4gofcarbonfibreat3cmlengths)dependingonthe amountaddedandthelengthofindividualfibres. Theamountofcarbonfibreaddedtoeachdesignscenariowasvariedbyweight(0.5%,0.76% and1%ofclayweight)andbylength(3cmand6cmindividualfibrelengths).inordertobetter understandtheimpactofeachofthesevariations,comparisonsofmeasuredflowratesare madebetweendiscswithoutcarbonfibre(disctype1)andthosewithvaryingamountsof carbonfibre(2g DiscTypes6and7,3g DiscTypes2and3,and4g DiscTypes5and6of carbonfibreperdisc)andthosewithvaryinglengthsofindividualfibres(3cm DiscTypes3,5, and7,and6cm DiscTypes2,4,and6).Theaveragemeasuredflowratebyweightofcarbon fibreaddedperdiscisasfollows:2g=443ml/hr,3g=482ml/hr,and4g=593ml/hrimplying graphicalrepresentationofthedata.thesquaredatapointssignifythemeasuredflowratesfor eachdisctypeandthediamonddatapointsaretheaverages.fromthegraphitcanbeseenthat thereisastronglinearrelationship(r 2 =0.93)betweentheamountofcarbonfibreaddedand theflowrate.also,thevariationintheflowrateappearstodecreasewithanincreasingquantity ofcarbonfibre. 69

76 FlowRateVs.CarbonFibreWeightperDisc 625 FlowRate(mL/hr) y=75.00x R²= WeightofCarbonFibreperDisc(g) Figure4W1:FlowRateVariationbyWeightofCarbonFibreperDisc Whencomparingtheflowratebetweendiscswithvaryinglengthsofindividualcarbonfibres,it isobservedthattheaverageflowrateisasfollows:3cm=497ml/hrand6cm=515ml/hr. Thisimpliesthatapositiverelationshipexistsbetweentheflowrateandthelengthoffibres;as theflowrateincreaseswithincreasesinfibrelength.however,asshowninfigure4@2,this relationshiponlyholdstrueforthosediscswith2gofcarbonfibreperdiscand,infact,theflow ratedecreaseswithincreasingfibrelengthforthosediscswith3gand4gofcarbonfibrein them.therefore,itcannotbestatedconclusivelythatincreasingthelengthoffibreswill increasetheflowrate.additionally,itdoesappearthatvariationsinflowratedecreasewiththe longerlengthofindividualfibres. 70

77 FlowRateVs.LengthofIndividualCarbonFibres 650 FlowRate(mL/hr) Average 2g 3g 4g Linear(Average) Linear(2g) Linear(3g) Linear(4g) LengthofIndividualCarbonFibres(cm) Figure4W2:FlowRateVariationbyIndividualCarbonFibreLengths BacteriaAttenuationData AsummaryofresultsforlaboratorytestingoftheCWFdiscsforEcolireductionsfromspiked watersareprovidedintable4@3.thediscswithoutcarbonfibre(disctype1)reducedecoliby ameanlrvof4.0whilethediscswithcarbonfibre(disctypes2through7)reducedecolibya meanlrvrangingfrom ,withtheinfluentE.coliconcentrationsasreportedin Section3.3.AnANOVAcomparisonofdifferencesbetweendisctypesshowedsignificant differencesforthereductionofecoli(p=0.0005);however,twomeansamplecomparison(t) testsbetweendisctypes(table4@4)indicatedthatonlyeightofthe21discpairingsshowed significantdifferencesinecolireduction(1@6,2@6,3@6,5@6,7@6,1@4,7@4,and1@3)witha95% significance.agraphicalrepresentationoftheecoliattenuationresultsisincludedinfigure4@3. 71

78 Table4W3:SummaryofEcoliattenuationdata DiscScenario %Removal StdDev StdErrMean LRV n Table4W4:Summaryofmeansamplettestsbetweendisctypes DiscType Pair Difference pvalue 1@ <0.0001* 7@ * 2@ * 5@ * 1@ * 3@ * 7@ * 1@ * 2@ @ @ @ @ @ @ @ @ @ @ @ @ *Starredvaluesindicatethatasignificant differenceexistsforecolireductionbetween thedisctypesintheindicatedpair 72

79 Figure4W3:GraphicalrepresentationofEcoliattenuationresults 73

80 Analysis Theremovalratesachievedduringthelaboratorytestingforalldisctypesarewithintherange ofthosefoundintheliterature(asdescribedinsection2.2.1,theaveragebenchmarkstandard forecoliremovaleffectivenessis97±3%,simonisandbasson,2011),whichshowsthatthe fabricateddiscsarecomparabletolowcostcwfscurrentlybeingused. Whencomparingdiscswithoutcarbonfibre(DiscType1)tothosewithcarbonfibre(DiscTypes variationthantheotherdisctypes.theanovatestindicatedthatasignificantdifferenceexists threedisctypes(disctypes3,4,and6)outofthesixwithcarbonfibreactuallyhavesignificant oneswiththelowestecoliremovalratesaswellasthehighestvariation.thisisanoteworthy observationasthismeansthattheadditionofcarbonfibreincertainquantitiesandlengths doesnotsignificantlychangetheecoliremovalrateofthediscs.thettestsalsoindicatethat DiscType6hassignificantlydifferentmeanEcoliremovalratesthanmostoftheotherdisc types(disctypes1,2,3,5,and7).thiscouldbebecausetheresultsfromdisctype6(2gof carbonfibreof6cmindividualfibrelengths)werehighlyvariableanddisctype6hasthe higheststandarddeviation(0.9062)ofallsevendisctypes. 74

81 PercentRemovalofEcolibyDiscType %EcoliRemoval DiscType Figure4W4:PercentRemovalofEcolibyDiscType Inordertobettercharacterizetheimpactofaddingcarbonfibretothediscs,comparisonsof percentremovalratesaremadebetweendiscswithoutcarbonfibre(disctype1)andthose withvaryingquantitiesofcarbonfibreperdisc(2g DiscTypes6and7,3g DiscTypes2and 3,and4g DiscTypes5and6)andthosewithvaryinglengthsofindividualfibres(3cm Disc Types3,5,and7,and6cm DiscTypes2,4,and6).Theaveragepercentremovalrateby weightofcarbonfibreaddedperdiscisasfollows:2g=99.61%,3g=99.78%,and4g=99.68%. Thisindicatesthatthebacteriaattenuationratedoesnotvaryconsistentlywithincreasing amountsofcarbonfibreperdisc.figure4@5showsagraphicalrepresentationofthedata.the squaredatapointssignifythepercentecoliremovalratesforeachdisctypeandthediamond datapointsaretheaverages.thevariationinremovalratesdoesnotappeartoincreaseor decreaseconsistentlywithachangeinamountofcarbonfibreperdisc. 75

82 PercentEcoliRemovalVs.WeightofCarbonFibreper Disc %EcoliRemoval y=0.0386x R²= WeightofCarbonFibreperDisc(g) Figure4W5:PercentEcoliRemovalbyWeightofCarbonFibreperDisc WhencomparingthepercentremovalratesofEcolibetweendiscswithvaryinglengthsof individualcarbonfibres,itisobservedthattheaverageremovalrateisasfollows:3cm=99.81% and6cm=99.57%.thisimpliesthatanegativerelationshipexistsbetweentheecoliremoval rateandthelengthoffibres;theecoliremovalratedecreaseswithanincreaseinfibrelength. However,asshowninFigure4@6,thisrelationshipdoesnotholdtrueforthosediscswith3gof carbonfibreperdiscastheremovalrateincreaseswithincreasingfibrelength.therefore,it cannotbestatedconclusivelythatincreasingthelengthofcarbonfibreswilldecreasetheecoli attenuationrate.additionally,itdoesappearthatthevariationinremovalrateincreaseswith thelongerlengthofindividualfibres.anadditionalfactorinbacteriaremovalisporetortuosity. Voidspacesthataremoretortuousarebetteratretainingbacteriathanvoidspacesthatare cylindricalinshape.theadditionofcarbonfibremaybecreatingvoidspacesthataremore cylindricalshaped. 76

83 99.94 PercentEcoliRemovalVs.LengthofIndividualCarbonFibres %EcoliRemoval Average 2g 3g 4g Linear(Average) Linear(2g) Linear(3g) Linear(4g) LengthofIndividualCarbonFibres(cm) Figure4W6:PercentEcoliRemovalbyLengthofIndividualCarbonFibres OthertrendsinthedatawerealsoexploredincludingcomparingdiscweighttoEcoliLRV (Figure4@7)andcomparingflowratetoLRV(Figure4@8).Inbothfigures,thediamonddata pointsindicatediscswithoutcarbonfibrereinforcement,andthesquaredatapointsindicate discswithcarbonfibrereinforcement.incomparingdiscweighttolrv,apositiverelationship (R 2 =0.72)wasfoundforthediscswithoutcarbonfibrereinforcementwhilenocorrelation(R 2 = 0.003)wasfoundforthediscswithcarbonfibrereinforcement.Thisindicatesthatdiscweight, andthereforediscthickness,isanimportantfactorinthebacterialrvfortraditionalcwfs withoutreinforcement.theadditionofcarbonfibremakesthecwfdiscslesssensitivetodisc weightmeaningthatusinglessrawmaterialispossiblewhileachievingsimilarbacterialrvs.in comparingflowratewithbacterialrv,nostrongcorrelationwasobservedeitherforthediscs withoutcarbonfibrereinforcement(r 2 =0.02)orwithcarbonfibrereinforcement(R 2 =0.25). 77

84 Theweaknegativerelationshipobservedforthediscswithcarbonfibrereinforcementimplies thatthehigherflowratesarepotentiallycausedbysomelargervoidspacesthatwouldallow bacteriatoflowthroughthediscsmorereadily. 5 DiscWeightvs.LogReduceonValue LogReduceonValue y=0.003x R²=0.003 y=0.07x@18.60 R²= DiscWeight(g) Figure4W7:Discweightvs.logreductionvalue 78

85 FlowRatevs.LogReduceonValue LogReduceonValue y=0.01x+3.64 R²=0.02 y=@0.00x+3.61 R²= FlowRate(mL/hr) Figure4W8:Flowratevs.logreductionvalue EquiWbiaxialFlexuralTestData Atypicalload@extensioncurvefromthedatatakenduringtheequi@biaxialflexuraltestingis includedinfigure4@9.thebreakingloadwascharacterizedastheinitialpeakonthecurveand thisvaluewasusedtocalculatetheequi@biaxialflexuralstrengthforeachdisc.moredatathan wasneededwasrecordedastheend@of@testwassettobewhenthecrossheadextension reached20mm.thepeaksofthecurvecreatedaftertheinitialwereduetothebrokendisc piecesshiftingandresistingtheloadringasitcontinuedtoextendtowardthesupportring.the discstypicallyfailedwithcrackpatternsanexampleofwhichisshowninfigure4@10. 79

86 LoadWExtensionCurveforDisc2C 0.25 Load(kN) Extension(mm) Figure4W9:TypicalloadWextensioncurve Figure4W10:Typicalfaileddiscpoststructuraltest 80

87 Oncethebreakingloadforeachdiscwasdeterminedfromthedatacollecteditwasusedto valueofpoisson sratiousedwas0.24.thisvaluewasobtainedbyaveragingvaluesusedfor where: σ f =equi@biaxialflexuralstrength(mpa) F=breakingload(N) h=discthickness(mm) ν=poisson sratio D S =diameterofsupportring(mm) D L =diameterofloadring(mm) Table4W5:Summaryofequibiaxialflexuraltestresults DiscType Equi@biaxialStrength (Mpa) StandardDeviation n Analysis Whencomparingtheequi@biaxialflexuralstrengthofthediscswithoutcarbonfibre (DiscType1=0.293MPa)totheaverageofthosewith(DiscTypes2through7=0.220MPa)the datasuggeststhataddingcarbonfibremakesthediscslessstrong.inordertobetter characterizetheimpactofaddingcarbonfibretothediscs,comparisonsofequi@biaxialflexural strengtharemadebetweendiscswithoutcarbonfibre(disctype1)andthosewithvarying amountsofcarbonfibre(2g DiscTypes6and7,3g DiscTypes2and3,and4g DiscTypes 5and6ofcarbonfibreperdisc)andthosewithvaryinglengthsofindividualfibres(3cm Disc 81

88 Types3,5,and7,and6cm DiscTypes2,4,and6).Theaverageflexuralstrengthbyweightof carbonfibreaddedperdiscisasfollows:2g=0.227mpa,3g=0.262mpa,and4g=0.170.this squaredatapointssignifytheflexuralstrengthforeachdisctypeandthediamonddatapoints aretheaverages.thevariationsinstrengthwithineachamountofcarbonfibreaddeddonot appeartoincreaseordecreaseconsistentlywithachangeinamountofcarbonfibreperdisc. EquiWbiaxialFlexuralStrength(MPa) FlexuralStrengthVs.WeightofCarbonFibreperDisc Figure4W11:EquiWbiaxialFlexuralStrengthbyWeightofCarbonFibreperDisc individualcarbonfibres,itisobservedthattheaveragestrengthisasfollows:3cm=0.235mpa and6cm=0.205mpa.thisimpliesthatanegativerelationshipexistsbetweentheflexural strengthandthelengthoffibres;asinthestrengthdecreaseswithanincreaseinfibrelength. 82 R²= WeightofCarbonFibreperDisc(g)

89 carbonfibreperdiscastheflexuralstrengthincreaseswithincreasingfibrelength.therefore,it biaxialflexuralstrength.additionally,itdoesappearthatthevariationinflexuralstrength decreaseswiththelongerlengthofindividualfibres. FlexuralStrengthVs.LengthofIndividualCarbonFibres EquiWbiaxialFlexuralStrength(MPa) Average g 3g g Linear(Average) Linear(2g) Linear(3g) Linear(4g) 3 6 LengthofIndividualCarbonFibres(cm) Figure4W12:EquiWbiaxialFlexuralStrengthbyLengthofIndividualCarbonFibres Commentary Theprecedingresultsareunexpected.Theoretically,theadditionofareinforcingfibretothe CWFdiscmatrixshouldhaveincreasedtheequi@biaxialflexuralstrengthofthediscsduetoload transferringfromtheclaymatrixtothereinforcingcarbonfibres.eventhoughrandomlyarrayed fibrereinforcementsaretypicallyleasteffectiveatstrengtheningmaterials,somestrength enhancementwasexpected.arandomarraywasselectedasitishowitwouldbeimplemented atthecwffactoryincambodiathatthesediscsweremodeledafter.randomlyarrayed 83

90 reinforcementsmakeanisotropiccompositethatischeapertofabricatethancompositeswith continuousfibrereinforcement. fabricationcausedbydifferentialthermalexpansion,whichwaspotentiallyobservedinthe (PerformanceComposites (McKinstry,1965).Inthiscasethethermal expansionvalueofthematrixishigherthanthatofthecarbonfibrecausingstrainmismatches. Thisisnotidealasthecarbonfiberisbetterabletowithstandtensilestrains.Thediffering thermalexpansionpotentiallyimpactedtheinterfacialpropertiesbetweenthekaolinitematrix andthecarbonfibreleadingtoafibre/matrixbondthatwastooweak.thisreferstoan adhesivefailurebetweenthecarbonfibreandclayleadingtodisbanding(figure4@13).anideal fibre/matrixbondisabalancebetweenweakandstrongasastrongfibre/matrixinterface lowersthefibrecriticallengthbutaweakerfibre/matrixinterfaceallowsstrengthening mechanismstooccursuchasfibrebridging,fibrepull@out,matrixmicrocracking,etc.that minimizecatastrophicfailures.inthiscaseitappearsasiftheinterfacialbondbetweenthe carbonfibrereinforcementandthekaoliniteclaymatrixwastooweaktherebyreducingthe equi@biaxialflexuralstrengthofthecwfdiscs. 84

91 Figure4W13:Brokendiscshowingsurfacecracksanddisbondedcarbonfibre Theapproximatecostofthecarbonfibreusedinthisstudy(6Ktow)isUS$0.036/50cm.The totallengthofcarbonfibreusedis500cm 1000cmperdisc,dependingontherecipe,ora perpotusedbyrdic(8000g)allowsanestimateofscaletobemade.thediscsare approximately12timessmallerthanthepotsmadebyrdicmeaningthatthecostofcarbon potentiallylimittheaccesstothesefiltersbythepoor. 85

92 4.3. References Brown,J.(2007).Effectiveness*of*Ceramic*Filtration*for*Drinking*Water*Treatment*in*Cambodia. DoctorofPhilosophy.UniversityofNorthCarolina.ChapelHill PerformanceCompositesLtd.(Nodate).Mechanical*Properties*of*Carbon*Fibre*Composite* composites.com/carbonfibre/mechanicalproperties_2.asp.accessedonlinejuly31,2012. Simonis,J.,andBasson,A.(2011).Evaluation*of*a*low?cost*ceramic*micro?porous*filter*for*

93 ChapterFive:ConclusionsandRecommendations 87

94 5. ConclusionsandRecommendations 5.1. Summary Whilepeopleworldwidehavemadesignificantgainsinrecentyearsinaccesstopotable drinkingwater,hugedisparitiesexistbetweenaccessbytherichandthepoor.withoutdirect accesstowaterinthehome,watermustbecollectedelsewhereandthentransportedto,and storedin,thehomepriortouse.microbialcontaminationofwaterduringthecollection, transportation,andstorageofwaterislikely.anumberofpoutechnologiesexisttotreatwater inthehomepriortouse.cwfsareahouseholdleveltechnologythathavebeenshowntobe effectiveatremovalofpathogensfromdrinkingwaterandreducingtheincidenceofdiarrheal disease;however,thecwfstypicallyonlylastapproximatelytwoyearsmainlyduetobreakage. Thisresearchstrivedtoexaminethepotentialforcarbonfibretoimprovethemechanical characteristicsofthecwfelementtoimproveitslengthofuseinthefieldwhilemaintaining,or improving,existingflowandbacteriaattenuationcapabilities.giventhatcwfsaregainingmore widespreaduseinmanycountriesworldwide,extendingtheirlifespanofusewouldhave significantvalue.thefourprimaryobjectivesofthisresearchareto: PerformE.coliattenuationtestingontheCWFdiscstodeterminebacteriaremoval characteristics;and, 4. PerformstructuraltestingontheCWFdiscstodeterminestrengthcharacteristics. 88

95 Sevendisctypeswerecreatedbyvaryingthequantityofcarbonfibreperdisc(0.5%,0.76%,and 1%ofclayweightwhichequatesto2g,3g,and4gofcarbonfibreperdisc,respectively)andby length(3cmand6cmindividualfibrelengths).threereplicatesofeachofthesevendisctypes werefabricated,testswereconducted,thedatawascollectedandanalyzed,andtheresultsare presentedhere Conclusions Relationshipsofdisctypesandflowrate,bacteriaattenuation,andflexuralstrengthwere evaluatedinthisstudy.asummaryofthefindingsfromthisstudyinclude: Flow%Rate%Through%the%Discs% TheCWFdiscswithcarbonfibrereinforcementhadanaverageflowrateapproximately 6timeshigherthanthediscswithoutcarbonfibrereinforcement. Astrongpositive,linearrelationship(R 2 =0.93)existsbetweentheweightofcarbon fibreperdiscandflowrate. Arelationshipcouldnotconclusivelybemadebetweenthelengthofindividualfibres andflowrate. Adecreaseinflowratevariabilitywasobservedwithanincreaseinboththeweightof carbonfibreperdiscandlengthofindividualfibres. E%coli%Attenuation%Characteristics% Thediscswithoutcarbonfibrehadhigherpercentremovalratesandlessvariationthan theotherdisctypes;however,thettestsrevealedthatonlythreedisctypes(disctypes 89

96 3,4,and6)outofthesixwithcarbonfibreactuallyhavesignificantdifferencesbetween meanecoliremovalrates.thismeansthattheadditionofcarbonfibreincertain quantitiesandlengthsdoesnotsignificantlydetractfromtheecoliremovalrateofthe discs.therewerenostrongcorrelationsfoundbetweenecoliremovalandweightof carbonfibreperdiscorindividuallengthofcarbonfibres. AdecreaseinEcoliattenuationvariabilitywasobservedwithanincreaseinlengthof individualreinforcingfibres. Apositiverelationship(R 2 =0.72)wasobservedbetweendiscweightandEcoliremoval forthediscswithoutcarbonfibrereinforcement,butnotforthereinforceddiscs meaningthatthesediscsarelesssensitivetodiscweightandusinglessrawmaterialis possiblewhileachievingsimilarbacterialrvs. NostrongcorrelationswereobservedbetweenflowrateandEcoliremovalforanyof thedisctypes. Equi8biaxial%Flexural%Strength%Characteristics% Theflexuralstrengthdataindicatethattheaddition(aspertheprocedureofaddition usedherein)ofcarbonfibreinanyweightorfibrelengthconfigurationmakesthediscs lessstrong. Itwasobservedthatthevariationinflexuralstrengthdecreaseswiththelongerlength ofindividualfibres. Thereductioninstrengthispotentiallyexplainedbyresidualstress@straindistributions causedbydifferentialthermalexpansionduringfiring.kaolinitehasamuchhigher 90

97 thermalexpansioncoefficientthancarbonfibre,makingthefibre/matrixbondtooweak forthestressloadtotransferfromtheclaymatrixtothereinforcingcarbonfibres Recommendations resistanceandhenceprovidingaccesstowaterwithreducedconcentrationsofpathogensfora longerperiod.inlightofwhatwaslearnedinthisstudy,thattherearebenefitstoadding reinforcingfibrestocwfelementsincludingtheincreaseinflowratewithoutalways significantlyreducingbacteriaremovalcapabilities,furtherworkcanbecompletedtobuildon thisresearchandcomeupwithanappropriatereinforcingconfigurationtoimproveboththe mechanicalcharacteristicsofcwfswhilemaintainingbacteriaremovalcapabilitiesatalowcost. Futurestudiesshouldinvestigate: Removalmechanismanalysis Inordertodeterminewhichremovalmechanismsareplayingaroleinattenuating bacteriaandtobettercharacterizetheimpactofaddingcarbonfibrereinforcement, testsshouldbeconductedusingasetsofsamplesbothwithandwithoutsilvernitrate. Differentfibreconfigurations Perhapsincreasingtheamountofreinforcingfibresperdiscwouldstrengthenthe clay/fibrematrixandallowstrengtheningmechanismstooccur.determiningawayto helpmakethebenefitsofaddingreinforcementmoreevident. 91

98 Differentfibretype DuetothefabricationoftheseCWFsrequiringfiringathightemperatures,usingan alternativefibrewithathermalexpansioncoefficientthatmorecloselymatchesthatof andimprovetheinterfacialpropertiesofthefilter.analternativefibremaybemore costeffectiveaswell. 92

99 AppendixA CarbonFibreSpecificationSheet 93

100 Cytec Carbon Fibers LLC 7139 Augusta Road Piedmont, SC Thornel Carbon Fiber Property Data Date: 20-Aug-2010 Customer: Customer Order No: Product: Cytec Order No: Total Quantity Shipped: BARRDAY CORPORATION T-300 6K 309 NT /10/ lb Based on random lot samplings, listed are the average physical properties of the lots included in this shipment. Trace Number: RG6G0801 Quantity Shipped: 417 lb Mfg Date: 03-Aug-2010 Yield Fiber Density Tensile Strength Sacma Modulus Young's Modulus Elong** Sizing g/m g/cc ksi Msi Msi % Strain % AVG The material shipped on this order is in compliance with Cytec Carbon Fibers' PAN property data requirements. **Elongation is a calculated value based on Tensile Strength / Modulus x 100. Report Number: SC_PROP Page 1 of 1