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1、SlowSandFilterFlowControlbyChrisBoone,AndreaGruber,AlexMikszewski,andMichaelSorensenAbstractUnregulatedflowratestypicalof“pointofuse”devicescanproducewaterunsafeforhumanconsumption.Inordertoimprovetheperformanceofsuchdevices,andinparticularslowsandfilters(SSF)foruseatthehousehold
2、levelintheGlobalSouth,anefficientandsimpleflowcontrolmechanismisrequired.TheaimoftheresearchsummarizedinthispaperwastodesignaflowcontroldevicetoensureconsistentflowthroughaSSF.Tocharacterizetheproblem,wehaveconstructedabatteryofmathematicalmodelstosimulateflowthroughaSSFalone,and
3、aSSFcoupledwithvarioussimpleheadlossdevices.Whilethesemodelsproducedinterestingandtellingresults,thesesimplemechanismsdonotappeartoprovideaneffectivesolutiontotheproblemathand.Instead,aconstantheaddevicewasdeveloped,andaprototypebuiltandtested.Overthetrialruns,flowratesthroughour
4、deviceconsistentwithsafewaterproductionwereobserved,thoughtheflowratewasneverconstantforanentirerun.Rather,theflowratefluctuatedbetweenahighvalueandalowervalue.Operatinginstructionsandrecommendationsforfurthermodificationstothedevicearealsogiven.ContextTheprimaryobjectiveofthisde
5、signprojectistoinvestigatemethodsofcontrollingflowtoimprovetheefficacyof“point-of-use”(POU)drinkingwatertreatmentdevicesforuseinthecontextoftheGlobalSouth.Althoughmanydifferenttypesofthesedevicesareused,suchascandlefiltersandclaypotfilters,thisstudyfocusesonflowcontrolthroughsmal
6、l-scaleslowsandfilters(SSF),butmaybeextendedtoothertypesoftreatmentdevices.Sincethesefiltersareintendedtotreatsmallamountsofwaterinthehome,theflowofwateraddedtothedeviceisnotconstant;rather,acertainquantityofwater(hereassumedtobe20liters)isaddedallat10once,resultinginveryquickini
7、tialflowratesthattaperoffastheamountofyet-to-be-treatedwaterabovethefilterdecreases.Thesehighinitialflowratescancausetheinitialremovalefficiencyofthefilterstobesignificantlylessthandesired.Therefore,amechanismtomaintainaconstantflowratethroughthefiltermayhelpimproveitspathogenrem
8、ovalefficiency.Althoughtheinitialgoalwas
