电絮凝InTechElectrocoagulationfortreatmentofind

Chapter11©2012AliandYaakob,licenseeInTech.ThisisanopenaccesschapterdistributedunderthetermsoftheCreativeCommonsAttributionLicense(),whichpermitsunrestricteduse,distribution,andreproductioninanymedium,providedtheoriginalworkisproperlycited.ElectrocoagulationforTreatmentofIndustrialEffluentsandHydrogenProductionEhsanAliandZahiraYaakobAdditionalinformationisavailableattheendofthechapter[1],chemicaltreatment[2]andElectrocoagulation[3].Biologicalandchemicaltreatmentsofwastewaterareusuallyassociatedwiththeproductionofgreenhousegasesandactivatedsludgealongwithsomeotherlimitationsregardingrequiredareaandremovalofresidualchemicalsrespectively.Ontheotherhand,Electrocoagulationisanextremelyeffectivewastewatertreatmentsystem,removingpollutantsandproducinghydrogengassimultaneouslyasrevenuetocompensatetheoperationalcost[3].Electrocoagulationhasbeendocumentedpositivelytotreatthewastewaterfromsteamcleaners,pressurewashers,textilemanufacturing,metalplaters,meatandpoultryprocessors,commerciallaundry,miningoperations,municipalsewagesystemplantsandpalmoilindustrialeffluents.Aroundtheworld,45millionmetrictonsofpalmoilhasbeenproducedin2009[5].Approximately0.65tonsofrawpalmoilmilleffluent(POME)isproducedforeverytonofprocessedfreshfruitbunches(FFB).Alargequantityofwaterisnecessarytoprocessthepalmfruitforoilproduction[6].Furthermore,POMEcontributes83%oftheindustrialorganicpollutionloadinMalaysia(Vigneswaranetal,1999).ThePOMEisrichinorganicElectrolysis228carbonwithachemicaloxygendemand(COD)higherthan40g/Landnitrogencontentaround0.2to0.5g/Lasammonianitrogenandtotalnitrogen.POMEcanalsobedescribedasacolloidalsuspensionof95–96%water,0.6–0.7%oiland4–5%totalsolidsincluding2–4%suspendedsolids[7].Conventionally,POMEisusuallytreatedwithopenlagoontechnologybysubjectingittoanaerobictreatmentinopenpondsystemtoreducetheCOD&BOD,thispretreatmentmethodisassociatedwiththerisksofproductionofgreenhousegasesi.e.methaneasapollutanttotheenvironment[8].UsuallytheexistingconventionalmethodsforthepretreatmentofPOMEareexpensiveortakinglongretentiontimeandrequireavastpondarea.ParameterConcentration(mg/L)ElementConcentration(mg/L)Oilandgrease4000–6000Potassium2,270Biochemicaloxygendemand25,000Magnesium615Chemicaloxygendemand50,000Calcium439Totalsolid40,500Phosphorus180Suspendedsolids18,000Iron46.5Totalvolatilesolids34,000Boron7.6TotalNitrogen750Zinc2.3Ammonicalsnitrogen35Manganese2.0Copper0.89Table1.Characteristicsofpalmoilmilleffluent[4]ThischapteremphasizesontheuseofElectrocoagulationtechniqueasatooltopromotethetrendsofsustainabilityintheexistingindustrializedworld.Electrocoagulationtechnologywasusedsuccessfullytopre-treatthePalmoilmilleffluent(POME)asanelectrolytefortheremovalofpollutingfactorsasaresultofcoagulationandprecipitationofsuspendedsolidsfollowedbysedimentationundergravity.AluminiumandironelectrodeswereusedassacrificinganodestobeusedupinelectrolyticoxidationfortheproductionofAl(OH)3XH2OandFe(OH)3XH2Orespectivelyindifferentbatchexperiments.ThisstudywasalsopartiallyfocusedtocomparetheeffectivenessofAluminium(Al)andIron(Fe)aselectrodestoreducethepollutingnatureofPalmOilMillEffluent(POME)andsimultaneoushydrogenproductionduringElectrocoagulation(EC).Themetal(anode)basedcoagulantswerefoundenoughefficienttoreducethechemicaloxygendemand(COD)andturbidityofPOME.Theremarkablepollutantsremovalwasalsoassociatedwiththehydrogenproductionasrevenuetocontributetheoperationalcostofwastewatertreatment.Hydrogenproductionwasalsofoundhelpfultoremovethelightersuspendedsolidstowardssurface.TheelectricalinputsandfindingsweresubjectedtodeterminetheEnergyEfficienciesofPOMEtreatmentincomparisonwithwatertohighlighttheassociatedadvantageswithECofPOME.ThischapterisencompassingadetailedstudyoftherelatedtopicsingenerallinkedElectrocoagulationforTreatmentofIndustrialEffluentsandHydrogenProduction229withexperimentalfindings.Experimentalfindingshavealsobeendiscussedindepthwithreferencetothepublishedarticlesbyotherresearchers.ConceptsandmechanismsofcoagulationandElectrocoagulationhavebeenelaboratedcoveringthemaximumapplicationsandgainsintheindustrialsectorincontextwiththeliterature.Chemicalcompositionofthewastewaterandassociatedriskstotheenvironmentandhealthhasbeenincludedforthebetterundersta