TheRockyMountainWayTertiaryMBBRtechnology

The“RockyMountainWay”-TertiaryM.B.B.RtechnologyprovesinnovativesolutionforcoldweathernitrificationJasonBowman1*,JamesRobinson1,SarahHubbell1,JohnFitzgerald2,ScottSmith21-EntexTechnologiesInc2-TownofOakCreek,Colorado*Email:[e-mail]ogicalReactor(MBBR)systemsarereceivingincreasingrecognitionforBNRprocesses.Theprimarypurposeofthesesystemsistoincreasetheamountofstabilizedbiomasswithinagivenbiologicalreactorbyintroducingindependentlymovingplasticcarriers.Thetechnologyoffersaprotectedsurfaceformicroorganismstocolonize.Inthisregard,microorganismsacclimatizetoawiderangeofconditionsmorereadilythanconventionalsuspendedphasesystems.Becauselittleornoadditionaltankageisrequired,thesesystemsareanidealsolutionforplantswithlimitedroomforexpansion.Inthespringof2010,theTownofOakCreek,Coloradoretrofitteditsexistingtreatmentsystemwithapost-nitfricationMBBR.A30dayperformancetestbeganinFebruary2011.DuringthistimetheplanttestedtheMBBR’sabilitytonitrifyattemperaturesatorbelow5°C.TheMBBRsystemwasabletosuccessfullyachievelowtemperaturenitrificationandproduceanammoniaeffluentconcentrationwellbelowtheregulatorypermit.KEYWORDS:MovingBedBiologicalReactor,ColdWeatherNitrification,Fixed-film,BiologicalNutrientRemoval,BioPortzTMINTRODUCTIONEnvironmentalfactorsinconjunctionwithpopulationgrowthhavegeneratedasubstantialincreaseinregulatorypressure,placingadditionalcapacitystressonwastewatertreatmentsystems.Waterpollutionissuesnowdominatepublicconcernsaboutnationalwaterqualityandmaintaininghealthyecosystems.Municipalitiesarefacedwiththedifficultdecisionofhowtomeetnewlyimposedeffluentrequirementswithlimitedbudgets.Despitethisincreasedattention,fundingsourcesfornewupgradesaregettingmoredifficulttofind,creatingtheneedforinnovativesolutions.Throughoutthepastfewyearsonesuchinnovativesolutionhasbeenidentifiedforcoldweathersystems:MBBR’s.MBBRprocessesarereceivingincreasingrecognitioninamultitudeofapplications.Theprimarypurposeistoincreasetheamountofstabilizedbiomasswithinagivenbiologicalreactor,therebyincreasingtreatmentcapacity.Thesesystemsofferasubstantialamountofprotectedsurfaceareaformicroorganismstoadheretoandcolonize.Inthisregard,microorganismsacclimatizetoavastsetofconditionsmorereadilythanconventionalsuspendedphasesystems.Becauselittleornoadditionaltankageisrequired,these4058WEFTEC2012Copyright©2012WaterEnvironmentFederation.AllRightsReserved.systemsareanidealsolutionforplantswithlimitedroom,orbudget,forexpansion.Theendresultisthatcoldweathernitrificationisaccomplishedatafractionoftheprice.NestledintheheartofYampaValleyatanelevationof7,200feet,theTownofOakCreek,ColoradoWastewaterTreatmentPlantwascomprisedofaseriesoflagoonswithsurfaceaerationfollowedbyasettlingpondandChlorinecontact.Theplantreceivedacombinationofwastefromthesurroundingtown,watershedsandanupstreammechanicalplant.Lagoontemperaturesoftendippedbelow4°Celsiusduringwintermonths.Duetotheadversesiteconditionsandthelimitedtreatmentcapacity,theplantwasunabletomaintainnitrificationthroughoutthewintermonths.Newregulatorypermitscappedwintereffluentammoniaat9mg/l.Thenewtreatmentobjectivesdemandedahigherkineticenvironment,capableofsustainingbiologicalactivityandnutrientremovalduringthewintermonths.Giventhelimitedfootprintforexpansion,apost-nitrificationMBBRwasdeterminedtobethebestoptiontomeetthetownsPreliminaryEffluentLimits(PELs),assetbytheColoradoDepartmentofPublicHealthandEnvironment(CDPHE).Afterarigorousreviewin2008underColorado’sNewTechnologyReview,thetowncommencedwiththepost-nitrificationMBBRupgradetoitsexistingplant.WithfundingfromtheUnitedStatesDepartmentofAgriculture(USDA),constructionbeganinthefallof2009.Theplant’supgradeconsistedofreplacingthesurfaceaeratorsintheprimarylagoonwithfinebubbleaeration,stagingtheprimarylagoonintomultiplecells(figure1)andconstructinganin-groundpost-nitrificationMBBR(figure2).Primaryeffluentwaspumpedthroughaheatexchanger(figure3)andintotwoMBBRcells,operatedinseries.EffluentfromtheMBBRwasfedintoasettlingpond.ClarifiedeffluentwasthenfedthroughaChlorinecontactchamberanddischarged.DESIGNAPPROACHTheMBBRsystemwasbasedonthefollowingdesignconditions:a.DesignMaximumInfluentFlow,mgd0.25b.TotalInfluentMBBRBOD,mg/l22-40c.InfluentMBBRTKN,mg/l3-40d.WinterTemperature,°C4.5Thedesignincludedtwoin-groundMBBRprocesstanks,tobeoperatedinseries,withacontrolandequipmentroomconstructedovertheprocesstanksandaccesshatchesfortheMBBRcells.Eachtankwas4.6-meterswideby4.3-meterslongwitha4.4-meternominalsidewaterdepth,providing87cubicmeters(22,776.6gallons)ofoperatingvolume.Eachreactorincludedcoarsebubblediffusedaerationforsubstratedistributionandmixingenergy,wedgewiremediaretentionscreenstoretaintheHDPEmediaelementswithintheMBBR(figure4),automatedScreenScourTMmechanism(asmanufacturedbyEntexTechnologiesInc,ChapelHill,NC),overflowandfoamscreens(figure5),processinstrumentation,positivedisplacementblowers,andatotalof72.4cubicmetersofmovingmedia(BioPortzTMmovingmediaasmanufacturedbyEntexTechnologiesInc,ChapelHill,NC).Theprocessaddedapproximately42,665sq