waterquality
influent
clearwell
groundwater
filter
disinfect
runoff
rawwater
odorscolorturbidity
flocs
coagulation
rapidsandfilter
sample水样
dissolvedoxygen溶解氧
Drinkingwater饮用水
Microorganisms\biomass微生物
Suspendedsolids悬浮固体
Advanced(post)treatment深度处理
(fine/coarse)Screen格栅
Settlingtank/sedimentationtank(basin)沉淀池
Clarifier澄清池
biofilm生物膜
activatedsludge活性污泥
aerationtank/basin/chamber曝气池
sludgeage污泥龄
packings填料
sludgedigestion污泥消化
Pump水泵
standpipe立管
WastewatertreatmentsystemsalsoreduceBODandnutrientloadingonthereceivingwater,andsomeremovetoxicchemicals.
Onemethodofarrivingattheproperreservoirsizeisbyusingthemasscurve.
Impuritiesenterthewaterasitmovesthroughtheatmosphere,acrosstheearth’ssurface,andbetweensoilparticlesintheground.
Primarytreatmentplantsutilizephysicalprocesses,suchasscreeningandsedimentation,toremovepollutantsthatwillsettle,float,orthataretoolargetopassthroughsimplescreeningdevices.
Mostsettingtanksarecircular,withrawsewageenteringatthecenterofthecircleandtreatedeffluentleavingtheperimeterofthetankasitoverflowsacrossaweir.
Insuspendedgrowthprocesses,themicroorganismsresponsiblefortreatmentaremaintainedinliquidsuspension
Sometestsrequirethemeasurementtobeconductedinthestreamsincetheprocessofobtainingasamplemaychangethemeasurement.
Probablythemostimportantmeasureofwaterqualityisthedissolvedoxygen.
Thecollection,processing,anddisposalofsludgecanbethemostcostlyandcomplexaspectofwastewatertreatment.
Theactualprocessofseparatingimpuritiesfromacarryingliquidbyrapidsandfiltrationinvolvestwophases:filtrationandbackwashing.
Removalofgritfromwastewatermaybeaccomplishedingritchambers
SludgewastingisanotherimportantstepintheSBRoperationthatgreatlyaffectsperformance.
Finerparticlesmaypenetratetheinnerporesofthemembrane,causinganincreaseinpressureloss.
Allofthebiologicalnitrogen-removalprocessesincludeanaerobiczoneinwhichbiologicalnitrificationoccurs.
BacteriawillusenitratetoconsumerbCODintheanaerobiczone,whichthenleaveslessrbCODavailableforphosphorus-storingbacteria.
Tricklingfilterswithrockpackinghavebeenacommon,simple,andlow-energyprocessusedforsecondarytreatmentsincetheearly1900s.
Rotatingbiologicalcontactorsisanattachedgrowthprocesswherethepackingisrotatedinthewastewatertreatmenttank.
Thebasicactivated-sludgetreatmentprocessconsistsofthefollowingthreebasiccomponents:(1)areactorinwhichthemicroorganismsresponsiblefortreatmentarekeptinsuspensionandaerated;(2)liquid-solidsseparation,usuallyinasedimentationtank;and(3)arecyclesystemforreturningsolidsremovedfromtheliquid-solidsseparationunitbacktothereactor.Animportantfeatureoftheactivated-sludgeprocessistheformationofflocculentsettleablesolidsthatcanberemovedbygravitysettlinginsedimentationtanks.
Activated-sludgefloccancontainbothaerobicandanoxiczones.Dissolvedoxygenanddissolvedsubstratesoutsideoftheflocdiffuseintotheaerobiczone,and,dependingontheDOconcentrationandconcentrationsofammoniaandbCOD,oxygenmaybedepletedatsignificantrateswithintheflocsothattheDOcannotpenetratetheentireflocdepth.Nitrateproducedbynitrificationintheaerobiczonecandiffuseintotheinneranoxiczonealongwithsubstratesothatdenitrificationoccurswithintheflocdepth.
ThePhostripprocesscombinesbiologicalandchemicalprocessesforphosphorusremoval.Aportionofphosphorus-richreturnactivatedsludgeisdivertedtoananaerobicstrippingtankwherephosphorusisreleasedinsolution.Thephosphorus-richstrippersupernatantisthenprecipitatedwithlimeandthestrippedbiomassisreturnedtotheaerationtank.InthePhostripprocess,phosphorus-removalefficiencydependslessontheinfluentrbCODconcentrationsthanforotherbiologicalphosphorus-removalprocesses.
Theanaerobiccontactprocessovercomesthedisadvantagesofacomplete-mixprocesswithoutrecycle.Biomassisseparatedandreturnedtothecomplete-mixorcontactreactorsothattheprocessSRTislongerthanHRT.Gravityseparationisthemostcommonapproachforsolidsseparationandthickeningpriortosludgerecycle;however,asludgewithpoorsettlingpropertiesiscommonlyproducedandalternativeseparationprocessesmustbeusedorothermethodsmustbeemployedtoimprovesolidscapture.
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