Multiregional-PI-control-strategy-for-dissolved-oxygen-and-aeration-system

MultiregionalPIcontrolstrategyfordissolvedoxygenandaerationsystemcontrolatbiologicalwastewatertreatmentplantR.PiotrowskiDepartmentofControlSystemsEngineeringElectricalandControlEngineeringFacultyGdanskUniversityofTechnologyNarutowicza11/12,80-233Gdansk,Polandr.piotrowski@eia.pg.gda.plA.ZawadzkiDepartmentofControlSystemsEngineeringElectricalandControlEngineeringFacultyGdanskUniversityofTechnologyNarutowicza11/12,80-233Gdansk,Polandzawadzki_adam@o2.plAbstractThedissolvedoxygenisakeyparameterforbiologicalprocessesatwastewatertreatmentplant.Thedissolvedoxygentrackingproblemisoneofthemostcomplexandfundamentalissueofbiologicalprocesses.Thepaperproposesanewmultiregionalcontrolstrategyfordissolvedoxygentrackingproblem.Theaerationsystemisincludedinoverallcontrolstructure.ThecontrolmechanismwithintheoperatingpointareaisbasedonPIcontrollerswiththeTakagi-Sugeno-Kangmethodofdefuzzification.Theproposedcontrolstrategyisdesignedandtestedbasedontherealdatarecords.ItisappliedtobiologicalwastewatertreatmentplantatNowyDworGdanski,NorthernPolandandisvalidatedbysimulation.1.IntroductionThewastewatertreatmentplant(WWTP)isacomplex,nonlinearbiological-chemical-physicalsystemwithstronginteractionsbetweenprocesses.Biologicalprocessesaredifficulttocontrolduetolargedisturbancessuchasinflowandload,nonlinearity,time-varyingandcomplexitywithstrongcouplingoftheprocessvariables.Thedissolvedoxygen(DO)levelinaerobictankshassignificantinfluenceonbehaviourandactivityofthemicroorganisminhabitingaWWTPandisusedindifferentoperationsattheWWTP(e.g.nitrification,denitrification,phosphorusremoval).Moreover,on-linemeasurementsofDOareamongthemostfrequentlyperformedonesataWWTP.TheDOconcentrationsinaerobiczonesofthebiologicalactivatedsludgereactorareconsideredasthemostimportantcontrolparameters.DuringthelastyearsdifferentcontrolalgorithmsfortheDOconcentrationhavebeendesignedintensively[e.g.17,1,5,8].OthercontrolstrategiesofDOcontrolusingN-NH4,N-NO3andP-PO4measurementshavealsobeeninvestigated[e.g.7,16].Inallcases,th