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SewageTreatmentControlSystemDesignBasedonIndustryEthernetZHANGHongwei,WANGXinhuan,YANYouyun,ZHANGTaoSchoolofElectricalEngineering&AutomationHenanPolytechnicUniversityJiaozuo,Chinazhanghw@hpu.edu.cnAbstract—Withtheincreasingattentionhasbeenpaidtoenvironmentprotectionbygovernment,sewagetreatmentworksisbecomingmoreandmoreconcerned.Therearemanyequipmentsandcomplicatedprocessintheprojectofsewagedisposal.ThepaperdiscussedtheapplicationofPLCandnetworkinthesewagetreatmentplant.Throughthecombinationoftheindustrialautomaticcontroltechnology,computertechnology,networkcommunicationstechnologyandconfigurationsoftware,theauthorhasdesignedandrealizedthedistributedcontrolsystemforsewagetreatment.TheprocesssupervisorylayerusesthefiberredundantindustrialEthernetnetwork.ThePLCcontrolsystemandthesupervisorysystemsoftwaredesignwerealsoproposedinthepaper.Byimprovingtheautomationlevelofsewagetreatmentfacilitiesandoptimizingtheprocessforsewagetreatment,thegoaltoreducetheworkloadandimprovetheefficiencyofsewagetreatmentcanbereached.Keywords-sewagetreatmentcontrolsystem;industrialEthernet;IFIX;PLCI.INTRODUCTIONInrecentyears,alongwiththerapiddevelopmentofChineseeconomy,watershortage,waterpollutionproblemsalsobecomesmoreandmoreserious.Forlargeandmedium-sizedcitiesthesewageandindustrialsewagehasadoptedsomemeasures,butinthetowns,thesewagetreatmentsituationisnotoptimistic.Thesewagetreatmenthasgreatsocialandeconomicbenefits.Butthesewagetreatmentprocessiscomplex;theproductioniscontinuousandparameterstestisdifficulty.Theoperationcostishighandeconomicreturnispoor.Inordertoeffectivelyusethesewageprocessingtechnology,makethesystemtooperatecontinuouslyandstably,adoptingadvancedautomaticcontroltechnologyinsewagetreatmenttoimprovetheplantautomationlevelhasbecomethekeyelementinsewagetreatment.Basedontheengineeringexample,fullyconsidersewagetreatmenttechnologyandEthernettechnology,thedesignandimplementationofasewagetreatmentcontrolsystembasedonindustrialEthernetisproposed.II.SEWAGEDISPOSALPROCESSInthesewagetreatmenttechnologythebiochemicaltreatmentmethodisappliedwidely.Theprocesscanbedividedintovariousforms,suchasactivatedsludge,biologicalmembraneandnaturalbiologicaltreatmentetc.Atpresentdomesticsewagetreatmenttechnologymostuseactivatedsludgeprocessanditsdeformation,suchasoxidationditchprocess,SBRprocessandsoon.Inthepaper,weselectOrbaloxidationditchprocess.ThesewagetreatmentprocessflowchartisshowninFigure1.Itismainlydividedintofilteringsystem,theoxidationditchbiochemicalprocesssystem,sludgedewatersystemandchlorinedisinfectionsystem.Becausetherearetremendousamountofimpurityandfloaterintherawsewage,beforeoxidationprocess,weneedtoundertakepre-treatment.Pre-treatmentremovesmaterialsthatcanbeeasilycollectedfromtherawwastewaterbeforetheydamageorclogthepumpsandskimmersofprimarytreatmentclarifiers.Theinfluentsewagewaterisstrainedtoremovealllargeobjectscarriedinthesewagestream.Thisisdonewithautomatedmechanicallycoarsescreens.Therakingactionofamechanicalbarscreenistypicallypacedaccordingtotheaccumulationonthebarscreensandwaterlevel.Afterpreliminaryfilter,thesewageisenhancedbytheliftpumptofinescreensforfurtherfiltering.Throughthemixing,precipitationandseparationinvotexgritremovalchamber,theheavysolidscansettletothebottomandsmallimpuritieswereseparatedfromsewage.Thesettledandfloatingmaterialsareremoved.Theremainingliquidisdistributedtodifferentoxidationditch.Alotofrotatingdishaeratorsandsubmersiblewaterimpellersareinstalledinoxidationditchtopushoxygenandpushtheflow.Afteraerobicbiologicalprocess,thesewageflowtothesecondarysedimentationbasin.Throughprecipitationthesludgeisseparatedfromsewage.Afterchlorinationthesupernatantflowintocontacttank.Thesludgewaterflowsintosludgepumpingstationforfurtherprecipitation.Therelativelyclearsewagewaterflowsintosewagepipeandbetreatedagain.Themudwastransporttothickeninganddewateringstationfordehydration.Finally,themudisfilteredintosolidsludge.978-1-4244-7161-4/10/$26.00©2010IEEEFigure1.sewagedisposalprocessflowchartIII.CONTROLSCHEMEDESIGNThesewagetreatmentprocessiscomplex;theproductioniscontinuousandparameterstestisdifficulty.Accordingtotheprocesscharacteristicsandnearestacquisitionandunitcontrolprinciple,thesystemusescomputerandPLCtoconstructdistributedcontrolsystem(DCS)whichhasonecentralcontrolstationandfourlocalcontrolstations.ThecommunicationnetworkusestheindustrialringtopologiesEthernetnetwork.Thecommunicationmediumselectsopticalfiber,whichhasthecharacteristicsofstronganti-interferenceandwidebandwidth.ThecontrolsystemstructureisshowninFigure2.Figure2.controlsystemstructureCentralcontrolstationisequippedwithtwoindustrialcontrolcomputers,oneprinterandoneprojector.Thecomputerisusedtomonitorthesewagetreatmentprocessandequipmentstatus.Itcanalsocontroltheequipments’operationandadjusttheparameters.Thetwosupervisorycontrolcomputersarewarmbackup.Accordingtothenearestacquisitionandunitcontrolprinciple,thePLCstationisdividedintofourcontrolarea.PLC1isresponsibleforthecontrolofcoarseandfinescreens,liftingpumpingstation,votexflowprocessequ