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外文翻译

毕业设计/论文

外文文献翻译

院系城市建设学院

专业班级环境1102　

姓　名易家喜

原文出处

评分

指导教师皮科武

华中科技大学武昌分校

20年月日

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原文：

MunicipalWastewaterTreatmentPlantBiologicalPhosphorusRemovalSystem

Abstract:

Theenhancedbiologicalphosphorusremoval（EBPR）systemdesign,thedeterminationofsludgeageandorganicphosphorusconcentrationeffectandtherelationshipbetweenpairsofdifferentlevelsofphosphorusgoalgivesthecorrespondingunit. 

Keywords:

:

EBPRanaerobicaerobicsludgeageSRTBOD5/ΔPphosphorusgoal 

        AsChina'snew'IntegratedWastewaterDischargeStandard'（GB8978-1996）Thepromulgationandimplementationofenhancedbiologicalphosphorusremovaltechnology（EnhancedBiologicalPhosphorusRemoval,referredtoasEBPR）inthenewsewagetreatmentplantprojectreceivedanincreasinglywiderangeofapplications.AstheneweffluentstandardsforTPwithhighrequirements,coupledwiththecomplexityofbiologicalphosphorusremoval,soittendstobecomeasewagetreatmentplantdesignandoperationofthedifficulty. 

        Themechanismofbiologicalphosphorusremoval,thecurrentconsensusviewisthatmorephosphateaccumulatingbacteria（PAO）thecompletionoftheuniquemetabolicactivitiesofphosphorusfromtheliquid（water）tosolid（sludge）conversion.Conventionalactivatedsludgephosphoruscontentof1.5%~2.0%（P/VSS）,whilethePAOcansludgephosphoruscontentincreasedto5%to7%,andthusbiologicalphosphorusremovalrequiresthecreationofsuitableenvironmentforthegrowthofPAO,whichsothattheproliferationofPAOgroups.Inthecraftsectionthroughaerobicanaerobicpre-set（space,suchasA/Ophosphorusremovalprocess;timing,suchasSBRprocess）toenablethePAOtoobtainselectivegrowth.PAOtoobtainselectiveadvantageduetoasubstantialabsorptionofwaterintheanaerobicvolatilefattyacids（VFAs）,andinthebodyintoapoly-β-hydroxybutyrate（Polyhydroxybutyrate,referredtoasPHB）,makingitnoothersegmentintheaerobicheterotrophicbacteriacompeteforwaterandresidualorganicmatter. 

Designofasludgeage 

1.1aerobicsludgeage 

        Asaheterotrophicbacteria,PAOthereisanecessaryconditionforgrowthistomeetitsrequiredminimumsludgeage.BecausePAOunderaerobicconditionsinthegrowthandreproduction,sohereistheminimumsludgeagereferstotheaerobicsludgeage.BetweenthegrowthrateofPAOotherheterotrophicbacteriaandautotrophicbacteria（nitrifyingbacteria）,withtheminimumneededforgrowth,sotheSRTisalsoinbetween.AtpresentthedesignoftheminimumrequiredPAOaerobicsludgeagegenerallybasedonexperienceinuse.Figure1indicatesthatthePAOandthenitrifyingbacterianeededforgrowth,theminimumsludgeageandtemperatureoftherelationshipbetweenthedesigninadditiontoconsideringtheminimumsludgeageshouldbeconsideredoutsideacertainsafetyfactor,thevalueof1.5ingeneral. 

        ThereasonislistedinFigure1,theminimumrequiredforthegrowthofnitrifyingbacteriaasnitrificationsludgeagewouldhaveanegativeimpactonthegrowthofPAO.Ifthesectionoccursintheaerobicnitrification,nitratewillbereturnedwiththesludgeintotheanaerobic,makingPAOdenitrifierscompetewithVFAs,thusunderminingtheselectiveadvantageofthePAO.Inaddition,backtotheanaerobicfermentationofnitratewillinterferewithresponse,becausedenitrifyingbacteriaunderanaerobicconditionswouldbethedirectuseofeasilydegradableorganiccompounds（1mgNO3-Nbackintotheanaerobicapproximately6mgCODisconsumed）,thusunderminingthetheirreactionintoVFAsbyfermentationprocess.Thus,whentheaerobicnitrificationoccurswhenthesegmenttodetermineanaerobicsludgeageshouldtakeintoaccounttheresultingadditionaldemandfororganics.AscanbeseenfromFigure1,whenthetemperatureislow,PAOandnitrificationbacterianeededforgrowth,alargerdifferencebetweentheminimumsludgeage,designorrun-timeiseasytomakethesystemtomeetthePAOinhibitthegrowthofnitrifyingbacteriagrowth,butasthetemperatureBothincreasedgraduallyapproach（>25℃,whenthetwoareequal）.VIP,UCTprocessduetoreturnfluidtoremoveNO3-NErShiPAOhasobviousadvantages. 

        Tomeettheminimumsludgeagewherethesystemphosphorusremovalefficiencywillbeincreasedasthesludgeagedecreases,whichisdueto:

①sludgeagereducestherateofincreaseinsoilleadtoproduction,sothatbyexcludingthenumberofphosphorusremovingsludgereduction;②PAOactivitiesinordertomaintainhislifeledtothedecompositionofphosphorussecondaryphosphorusrelease.Therefore,thebiologicalphosphorusremovalsystemtomeetthePAOgrowthundertheconditionsrequiredforashortersludgeageshouldbeused. 

1.2anaerobicsludgeage 

        ThecompletionofVFAsintheanaerobicPAOadsorption,transferandreleaseofphosphorusinvivo.ItisabsorbedphosphorusintheaerobicsectionwiththenumberofVFAsintheanaerobicadsorptionthenumberofcloselyrelated.IfthewaterinalargenumberofVFAsexist,PAOadsorptionofVFAscanquicklybecompletedatthistimerequireslessanaerobicsludgeage;andifonlypartoftheinfluentVFAs,youneedtocarryoutthefermentationoforganicmatterinanaerobicreactionsproduceVFAs,duetofermentationreactionwasslow,andthereforewillbecometheanaerobicfermentationreactiontothesizeofthecontrollingfactorsofSRT.At20℃inthepresenceofwater,ifneededVFAs,whileanaerobicsludgeagecouldbeasshort0.5d;ifthewaterdoesnotcontainVFAs,butitcontainseasilydegradableorganicmatterproducedbyfermentationreactionsrequiredforsufficientVFAs,whileanaerobicsludgeageofabout1.5d（20℃）;ifthewatercontainssomeofVFAs（stillneedpartofthefermentation）issludgeageof0.5~1.5d.Ontheotherhand,iftheinsufficientnumberofeasilydegradablesubstances,thentheslowdegradationoforganiccompoundsstillneedtofirsthydrolyzed,andthenthroughthefermentationreactionofVFAs,atthistimeoftheanaerobicsludgeagelonger（2.5~3d）.Atthispoint,ifthefermentationproducts（aseversludgefermentationproducts）intotheanaerobicpond,itwillimprovethephosphorusremoval. 

        UrbansewagewillbedeterminedaccordingtotheinfluentCODconcentrationofanaerobicMLSSquantityandthenumberofthetotalsystemofMLSSratio（Table1）.MLSSconcentrationinthecaseofunificationoftheratioofthenumberofanaerobicsludgeageandtheratiooftotalsystemsludgeage. 

Table1,theproportionofanaerobicbiomassandtherelationshipbetweentheinfluentCOD 

InfluentCOD（mg/L） 

AnaerobicMLSSquantityaccountsfortheproportionofthetotalsystemoftheMLSS 

"400 

0.20~0.25 

Fourhundredto700 

0.15~0.20 

"700 

0.10~0.15 

Twophosphorusremovaleffectandtherelationshipbetweenorganicmatter 

        PhosphorusremovalandCOD/TP,BOD5/TPandSBOD5/TPthevalueoftherelevant,whileitvarieswiththeprocess.Minimumrequiredforbiologicalphosphorusremovalleadstotheconceptoforganiccarbon（organicmatter）tolimitsewageandeffluentphosphoruslimits.Carbonlimitsthenumberofsewageisnotsufficienttoremoveallwaterandorganicphosphorus,andtheresultsofahighconcentrationofphosphorusinwater,itsconcentrationbythecorrespondinginfluentconcentrationsofphosphorusconcentrationandorganicmattertodetermine.Phosphoruslimitoforganicwastewatereffluentisrequiredfororganicphosphoruscontentismorethanthenumberoftheeffluentphosphorusconcentrationisverylowatthistime.Sowheninneedofagoodwaterquality,therawwaterqualityisaphosphoruseffluentlimitisexpected. 

        Throughtheunderstandingofcarbon-limitedwatergivesavarietyofEBPRprocessesrequiredfortheproportionoforganicmatterwithΔP.Theratioisundercarbonconstraintsdeterminedthroughtestingandtheactualproject,whileitalsoshowsthatthephosphorusremovalcapacityofthesystem.ThemostcommonlyusedratioistheratioofBOD5thesametothephosphorus（BOD5/ΔP）,itscalculationformulais:

                                    BOD5/ΔP=influentBOD5/waterTP-watersolubilityofP 

        Theuseofwatersolublephosphorusintheformulabecauseofaparticulatephosphorusinwaterisusuallyoutflowfromthesecondarysedimentationtank,whichisafunctionoftheefficiencyofthesecondarysettlingtank,buthasnothingtodowiththebiologicalprocesses.Table2providesavarietyofbiologicalphosphorusremovalprocessrequiredforatypicalBOD5,CODandtheratioofΔP. 

Table2EBPRprocessesrequiredforBOD5andCODandtheratioofΔP 

EBPRprocess 

BOD5/ΔP（mgBOD5/mgP） 

COD/ΔP（mgCOD/mgP） 

InadditiontoPandefficientprocesses（suchasnitrite-freeA/O-oriented,VIP,UCT） 

15~20 

26~34 

MediumEfficiencyInadditiontoPprocesses（suchaswithnitrificationandA/OandA2/O） 

20~25 

34~43 

InadditiontolowefficiencyofPprocesses（suchastheoxidationditch） 

"25 

"43 

        AscanbeseenfromTable2,whenthevalueofthesmallerBOD5/ΔPneedefficientphosphorusremovalprocess,becausesuchprocessesrequirelessremovaloftheorganicunitsofphosphorus.Efficientphosphorusremovalefficiencyishig