黎巴嫩污水处理技术TreatmentTechnologies

WASTEWATERTREATMENTTECHNOLOGIESMEDAWAREProf.GeorgeAyoubFacultyofEngineeringandArchitectureAmericanUniversityofBeirutOUTLINEOverviewoftheConventionalWastewaterTreatmentProcessDiscussionofExistingBiologicalTreatmentTechnologiesExamplesfromtheMediterraneanRegionExamplesfromtheLebaneseContextConventionalWastewaterTreatmentProcessPretreatmentinvolves:ScreeningGritRemovalOilseparationFlowequalizationDisinfectioncanuse:ChlorinecompoundsBromineChlorideOzoneUVRadiationChemicalTreatmentisusedinconjunctionwiththephysicalandchemicalprocesses:ChemicalprecipitationAdsorptionSludgeTreatmentandDisposalinvolves:grinding,degritting,blending,thickening,stabilization,conditioning,disinfection,dewatering,heatdrying,thermalreduction,ultimatedisposalBiologicalTreatmentInthecaseofdomesticwastewatertreatment,theobjectiveofbiologicaltreatmentis:•Tostabilizetheorganiccontent•ToremovenutrientssuchasnitrogenandphosphorusTypes:AerobicProcessesAnoxicProcessesAnaerobicProcessesCombinedAerobic-Anoxic-AnaerobicProcessesPondProcessesAttachedGrowthSuspendedGrowthCombinedSystemsAerobicMaturationFacultativeAnaerobicMajorAerobicBiologicalProcessesTypeofGrowthCommonNameUseSuspendedGrowthActivatedSludge(AS)CarbonaceousBODremoval(nitrification)AeratedLagoonsCarbonaceousBODremoval(nitrification)AttachedGrowthTricklingFiltersCarbonaceousBODremoval.nitrificationRoughingFilters(tricklingfilterswithhighhydraulicloadingrates)CarbonaceousBODremovalRotatingBiologicalContactorsCarbonaceousBODremoval(nitrification)Packed-bedreactorsCarbonaceousBODremoval(nitrification)CombinedSuspended&AttachedGrowthActivatedBiofilterProcessTricklingfilter-solidscontactprocessBiofilter-ASprocessSeriestricklingfilter-ASprocessCarbonaceousBODremoval(nitrification)ActivatedSludgeProcessTheaerationtankcontainsasuspensionofthewastewaterandmicroorganisms,themixedliquor.Theliquorismixedbyaerationdevices(supplyingalsooxygen)AportionofthebiologicalsludgeseparatedfromthesecondaryeffluentbysedimentationisrecycledtotheaerationtankTypesofASSystems:Conventional,Complete-Mix,SequencingBatchReactor,ExtendedAeration,DeepTank,DeepShaftAdvantages/DisadvantagesAdvantagesFlexible,canadapttominorpH,organicandtemperaturechangesSmallarearequiredDegreeofnitrificationiscontrollableRelativelyminorodorproblemsDisadvantagesHighoperatingcosts(skilledlabor,electricity,etc.)GeneratessolidsrequiringsludgedisposalSomeprocessalternativesaresensitivetoshockloadsandmetallicorotherpoisonsRequirescontinuousairsupplyTricklingFiltersThetricklingfilterorbiofilterconsistsofabedofpermeablemediumofeitherrockorplasticMicroorganismsbecomeattachedtothemediaandformabiologicallayerorfixedfilm.Organicmatterinthewastewaterdiffusesintothefilm,whereitismetabolized.Periodically,portionsofthefilmsloughoffthemediaAdvantages/DisadvantagesAdvantagesGoodquality(80-90%BOD5removal)for2-stageefficiencycouldreach95%Moderateoperatingcosts(lowerthanactivatedsludge)WithstandsshockloadsbetterthanotherbiologicalprocessesDisadvantagesHighcapitalcostsCloggingofdistributorsorbedsSnail,mosquitoandinsectproblemsRotatingBiologicalContactorsItconsistsofaseriesofcirculardisksofpolystyreneorpolyvinylchloridethataresubmergedinwastewaterandrotatedslowlythroughitThediskrotationalternatelycontactsthebiomasswiththeorganicmaterialandthenwithatmosphereforadsorptionofoxygenExcesssolidsareremovedbyshearingforcescreatedbytherotationmechanismAdvantages/DisdvantagesAdvantagesShortcontactperiodsHandlesawiderangeofflowsEasilyseparatesbiomassfromwastestreamLowoperatingcostsShortretentiontimeLowsludgeproductionExcellentprocesscontrolDisadvantagesNeedforcoveringunitsinstalledincoldclimatetoprotectagainstfreezingShaftbearingsandmechanicaldriveunitsrequirefrequentmaintenanceMajorAnaerobicBiologicalProcessesTypeofGrowthCommonNameUseSuspendedGrowthAnaerobicContactProcessCarbonaceousBODremovalUpflowAnaerobicSludge-Blanket(UASB)CarbonaceousBODremovalAttachedGrowthAnaerobicFilterProcessCarbonaceousBODremoval,wastestabilization(denitrification)ExpandedBedCarbonaceousBODremoval,wastestabilizationAnaerobicContactProcessUntreatedwastewaterismixedwithrecycledsludgesolidsandthendigestedinasealedreactorThemixtureisseparatedinaclarifierThesupernatantisdischargedaseffluent,andsettledsludgeisrecycledAdvantages/DisadvantagesAdvantagesMethanerecoverySmallarearequiredVolatilesolidsdestructionDisadvantagesHeatrequiredEffluentinreducedchemicalformrequiresfurthertreatmentRequiresskilledoperationSludgetobedisposedoffisminimalUpflowAnaerobicSludgeBlanketWastewaterflowsupwardthroughasludgeblanketcomposedofbiologicalgranulesthatdecomposeorganicmatterSomeofthegeneratedgasattachestogranulesthatriseandstrikedegassingbafflesreleasingthegasFreegasiscollectedbyspecialdomesTheeffluentpassesintoasettlingchamberAdvantages/DisadvantagesAdvantagesLowenergydemandLowlandrequirementLowsludgeproductionLessexpensivethanotheranaerobicprocessesHighorganicremovaleficiencyDisadvantagesLongstart-upperiodRequiressufficientamountofgranu