Ultrasound(US)-inducedcavitationisaneffectivewayinoxidizingorganiccontaminantsinwastewatereitherastheindependentoperationunitorincombinationwithotheroxidationmethods.Inthispaper,blackliquorandfiltrateafteracidifyingandsettlingweresonicated.Theeffectofworkingparametersonultrasonicdegradationofblackliquor,suchasdifferentcombinationmethods,frequency,powersupply,initialconcentration,pH,durationtime,ionicstrengthandcatalystwerestudied.Theresultswereasfollows:(1)Attheconditionsof40kHz,100W,4h,pHat6andtemperature30±2℃,utilizingUS/US-H2O2/US-Fenton,weak-orangefiltrateturnedtocolloidwiththeincreaseoftimeandlittlesedimentproducedaftersettling.EspeciallyfiltratecametobemilkwhitecollidesandupperwaterapproachedtonearlyachromaticbyUS-Fenton.ComparedwiththeUS,US-H2O2/US-FentonCOD(Chemicaloxidationdemand)removalratiocanincrease15%,30%respectively.Becauseofmorehydroxylradicalsproducedinthereactionprocess;(2)Attheconditionof100Wand4h,thedegradationefficiencyofblackliquorwasbetterat40kHzoverat20kHz.Moreoverblackliquorcanbebiodegradedeasily.Thosebasedonthatthebigmoleculeofcontaminantsinaqueoussolutioncanbechangedintothelittlemoleculewithultrasound(3)Attheconditionof40kHzand4h,theCODremovalratioofblackliquorwasmorehigherat60Wthanat80W,whiletheremovalratioofCODat60Wwasnearlyclosetotheratioat100W;(4)Theinitialconcentrationofblackliquorinfluencedtheeffectofsonochemicaldegradation;(5)ThevariationofpHhadnoeffectondegradation;(6)Thelongerthedurationtime,thegreatertheremovalratioofCOD.Butthisratioincreasedslowlyafter4h;(7)Adding0.2g/LNaCltochangetheionicstrengthoftheblackliquor,theCODremovalratiocanincrease10%;(8)ThedegradationratesincreasedbythecoexistentcatalystsofTiO2,Co2+andAg+.
