REMOVAL-OF-COD-AND-TURBIDITY-TO-IMPROVE-WASTEWATER

TheMalaysianJournalofAnalyticalSciences,Vol11,No1(2007):198-205198REMOVALOFCODANDTURBIDITYTOIMPROVEWASTEWATERQUALITYUSINGELECTROCOAGULATIONTECHNIQUEMohFaiqunNi’am*1,FadilOthman2,JohanSohaili2,ZulfaFauzia21CivilEngineeringDepartment,UniversitasIslamSultanAgung,Semarang,Indonesia2EnvironmentalDept.,CivilEngineeringFaculty,UniversitiTeknologiMalaysia,Johor,MalaysiaKeywords:Electrocoagulation,Feelectrode,Removalefficiency,Wastewatertreatment.AbstractElectrocoagulation(EC)isbecomingapopularprocesstobeusedforwastewatertreatment.TheremovalofCODandturbidityfromwastewaterbyECusingiron(Fe)electrodematerialwasinvestigatedinthispaper.Severalworkingparameters,suchaspH,currentdensity,andoperatingtimewerestudiedinanattempttoachieveahigherremovalcapacity.WastewatersamplewasmadefrommilkpowderwithinitialCODof1140mgL-1andturbidityof491NTU.Currentdensitywasvariedfrom3.51to5.62mAcm-2,andoperatingtimeofbetween30and50minutes.Theresultsshowthattheeffluentwastewaterwasveryclearanditsqualityexceededthedirectdischargestandard.TheremovalefficienciesofCODandturbiditywerehigh,beingmorethan65%and95%.Inaddition,theexperimentalresultsalsoshowthattheelectrocoagulationcanneutralizepHofwastewater.AbstrakElektrokoagulasi(EC)merupakansuatuprosesyangpopuleruntukdigunakanpadaperawatanairsisa.PenyingkiranCODdankekeruhandaripadaairsisaolehECyangmenggunakanmaterialelektrodbesi(Fe)telahdiselidikidalamkertaskerjaini.Beberapaparameter,sepertipH,kerapatanarusdanmasaperawatandikajidalampercubaanuntukmendapatkankadarpenyingkiranlebihtinggi.AirsisadibuatdaritepungsusudengannilaiawalCOD1140mgL-1dankekeruhan491NTU.Kerapatanarusdivariasidari3.51hingga5.62mAcm-2,danmasaperawatanantara30dan50minit.Keputusankajianmendapatibahawaefluenairsisasangatjernihdansesuaidenganpiawaipelepasan.EfisiensipenyingkiranCODdankekeruhanadalahtinggi,menjadilebihdari65%dan95%.Sebagaitambahan,keputusankajianjugamendapatibahawaelektrokoagulasidapatmeneutralkanpHairsisa.IntroductionThereuseofwastewaterhasbecomeanabsolutenecessity.Demandstothecleaningindustrialanddomesticwastewatertoavoidenvironmentalpollutionandespeciallycontaminationofpurewaterresourcesarebecomingnationalandinternationalissues.Innovative,cheapandeffectivemethodsofpurifyingandcleaningwastewaterbeforedischargingintoanyotherwatersystemsareneeded.Electrocoagulation(EC)duetosomeadvantagesoverchemicalcoagulationisbecomingapopularprocesstobeusedforwastewatertreatment.Electrocoagulationisnotanewtechnology[1].TreatmentofwastewaterbyEChasbeenpracticedformostofthe20thcenturywithlimitedsuccess[2].UsingelectricitytotreatwaterwasfirstproposedinUKin1889,andtheapplicationofelectrolysisinmineralbeneficiationwaspatentedbyElmorein1904[3].TheprincipleofECwasusedtotreatbilgewaterfromshipswasfirstpatentedin1906byA.E.Dietrich[4].Theelectrocoagulationissimpleandefficientmethodforthetreatmentofmanywaterandwastewaters.Ithasnotbeenwidelyacceptedbecauseofhighinitialcapitalcostsascomparedtoothertreatmenttechnologies.Inrecentyears,manyinvestigationshavebeenespeciallyfocusedontheuseofECowingtotheincreaseinenvironmentalrestrictionsoneffluentwastewater[5-8].Theuseofelectrocoagulationforthetreatmentofwastewaterhasbeenreportedbyvariousauthors,andseveraldifferenceswerefoundincomparisontothechemicalcoagulationprocess.AliteraturesurveyindicatesthatECisanefficienttreatmentprocessfordifferentwastes,e.g.solubleoils,liquidfromthefood,textileindustries,orcelluloseandeffluentsfromthepaperindustry[9-10].Electrocoagulationisaneffectiveprocessforthedestabilisationoffinelydispersedparticlesbyremovinghydrocarbons,greases,suspendedsolidsandheavymetalsfromdifferenttypesofwastewater[12-13].Electrocoagulationhasbeenproposedinrecentyearsasaneffectivemethodtotreatvariouswastewaterssuchas:landfillleachate,restaurantwastewater,salineMohFaiqunNi’ametal.REMOVALOFCODANDTURBIDITYTOIMPROVEWASTEWATER199wastewater,tarsandandoilshalewastewater,urbanwastewater,laundrywastewater,nitrateandarsenicbearingwastewater,andchemicalmechanicalpolishingwastewater[14].Alumuniumorironwereusuallyusedaselectrodesandtheircationsaregeneratedbydissolutionofsacrificialanodesupontheapplicationofadirectcurrent[8,10,13,15-17].ElectrocoagulationtechniquefortreatmentofwastewatersampleshavebeenconductedonalaboratoryscaleandgoodremovalofCOD,color,turbidity,anddissolvedsolidsatvaryingoperatingconditionshavebeenobtained[8,9,14-18].ExperimentalThisstudyistoinvestigatetheeffectofelectrocoagulation(EC)process.ThisresearchismainlyfocusedonthecapabilityofECtechnologytoimprovewastewaterquality,suchastoincreaseremovalefficienciesofCODandturbidity.DescriptionofECTechniqueECisanelectrochemicalwastewatertreatmenttechnologythatiscurrentlyexperiencingbothincreasedpopularityandconsiderabletechnicalimprovements.ECisacomplicatedprocessinvolvingmanychemicalandphysicalphenomenathatuseconsumableelectrodestosupplyionsintothewastewaterstream[19].ThemechanismoftheElectrochemicalprocessinaqueoussystemsisquitecomplex[6].Itisgenerallybelievedthattherearethreepossiblemechanismsinvolvedintheprocess:electro-coagulation,electro-flotatio