外文翻译.docx
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外文翻译.docx
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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
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