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pH1,2,1,1(1., 150090;2., 100875):(extracellularpolymericsubstances,EPS),pH,2,pHEPS,,EPS,.,(pH3),EPS50%,30%,65%～70%;(pH11),EPSpH720%～30%,15%,20%～50%.,,、、(pH3);,2EPSpH;,,.pHEPS、,EPS,.:;;pH;;:X703.1 :A :0250-3301(2007)07-1507-05:2006-07-13;:2006-11-10:(2005038197);(2003AFXXJ025):(1980～),,,,E-mail:budzheng@sohu.comEffectsofpHontheSurfaceCharacteristicsandMolecularStructureofExtracellularPolymericSubstancesfromActivatedSludgeZHENGLei1,2,TIANYu1,SUNDe-zhi1(1.SchoolofMunicipalandEnvironmentalEngineering,HarbinInstituteofTechnology,Harbin150090,China;2.CollegeofWaterSciencesKeyLaboratoryofWaterandSedimentSciencesMinistryofEducation,BeijingNormalUniversity,Beijing100875,China)Abstract:Tounderstandthemechanismsofextracellularpolymericsubstances(EPS)influencingsludgecharacteristics,changeinconstituentsofextractableEPSfrommunicipalwastewaterandbeveragewastewatersludgeatvariouspHwasinvestigated.Fouriertransforminfrared(FTIR)spectrophotometrywasusedtoanalyzetheeffectofpHonthefunctionalgroupsinEPS.Surfacechargewasmeasuredbycolloidtitration.Finally,surfacechargemeasurementsandmolecularstructureanalysiswereevidencedbyScanningElectronMicroscopy(SEM)observationofthesludgesamplesbeforeandafterEPSextractionatdifferentpH.Theresultsshowthatatstrongacidcondition(pH3),theextractableEPSarelowerthanthoseatneutralconditionbyabout50%including30%decreasinginpolysaccharidesand65%～70%inprotein.Atstrongalkalicondition(pH11),theextractableEPSarehigherthanthoseatneutralconditionby20%～30%includingabout15%increasinginpolysaccharidesand20%～50%inprotein.Hydroxylchangesbothatalkaliandacidcondition.Carboxylacid,polysaccharides,phenolicgroups,andaminogroupsinproteindisappearatacidcondition(pH3).NegativesurfacechargeofEPSfrombothofthesludgesincreaseswithpH.ObservationofsludgebySEMindicatesthatcomparedwithalkalicondition,acidconditionismoreeffectiveinmakingthebacterialcellbroken.TheresultssuggestthatpHchangestheconstituents,concentrationandfunctionalgroupsinEPS,consequentlythesurfacechargeofEPS.Asaresult,sludgecharacteristicsarechanged.Keywords:extracellularpolymericsubstances(EPS);sludge;pH;molecularstructure;surfacecharge (extracellularpolymericsubstances,EPS),3[1].,EPS()80%,50%～90%,15%,[2～5].EPS.Kang[6],EPS,Houghton[7]EPS;Urbain[1]EPS(SVI),Goodwin[8],Chao[9]EPSSVI.EPS.Morgan[10]EPS,、,EPS;Liao[11]28720077 ENVIRONMENTALSCIENCEVol.28,No.7Jul.,2007DOI:10.13227/j.hjkx.2007.07.017EPS,EPS,.pH,EPS,.[12]pH,[13][14]pH.,pH,、、.pHEPS,pHEPS,,pH,EPS.1 1.1 .1.1 Table1 CharacteristicsofthestudiedactivatedsludgeTSSmg·L-1VSSmg·L-1pH%2536083407.898.630886109007.296.21.2 1molLHNO3NaOHpH3、7113,,,.:,80℃、100kPa10min,8000rmin10min,,15℃,,EPS[15].1.3 1.3.1 MLSS、VSS、TP、TN[16].1.3.2 ,Folin-[17],[18];EPSPerkinElmerSpectrumGX;EPS[10].1.3.3 :,2.5%4℃24h,30%、50%、70%、80%、90%100%10min、.2 2.1 pHEPSpH,EPS1.1,2EPSpH.(pH3),EPSpH750%,30%,65%;EPSpH750%,30%,70%.(pH11),EPSpH720%,15%,20%;EPSpH730%,15%,47%.1 EPSpHFig.1 VariationofcompositionandconcentrationofEPSwithpH1508 28 ,pHEPS,pH,EPS(、、),EPS,.,pHEPS.2.2 pHEPSpH2.2,2EPSpH.(pH3),EPS,5.067.99,(pH11),2EPS,pH711,EPS51.EPSpHEPS,EPS 2 pHEPSFig.2 VariationofsurfacechargeofEPSwithpH.H+、OH-,、.2.3 pHEPSpHEPS(400～4000cm-1)32,2IREPS.3 pHEPSFig.3 FTIRspectraofEPSatvariouspH2 IRTable2 MainfunctionalgroupsobservedinIRspectracm-13000～3400OHEPSOH2926±10CH21720 CO1630～1680COⅠ()1580～1630C—HⅡ()N—H1400 COOH1240 COOH1230 COOH1030～1150C—O—C950～1120CH1000、 EPS.;,、()、(CH2);[19].EPSpH.3099(EPS)3065±20(EPS);1170～1560(EPS)1008～1611()、、(pH3),.EPS15097:pH,,EPS、,EPS,.2.4 pHEPS,pHEPS,4.4(a)EPS[20],4,EPS,,,1.4(b)～(d)EPS,,EPSEPS,、,EPS,,.4 Fig.4 Electronmicrographofactivatedsludgeatdifferentcondition EPS,,;,EPS,EPS,EPS,、,EPS-、、,,.3 (1)EPSpH.(pH3),EPSpH750%,30%,65%～70%;(pH11),EPSpH720%～30%,15%,20%～50%.(2)EPSpH,2EPS.,、、,,,H+、OH-、.(3),,EPS,;,EPS,.(4)pHEPS、,EPS、1510 28,.:[1]UrbainV,BlockJC,ManemJ.Bioflocculationinactivatedsludge,ananalyticalapproach[J].WatSciTech,1993,25:441～443.[2]FrlundB,PalmgrenR,KeidingK,etal.Extractionofextracellularpolymersfromactivatedsludgeusingacationexchangeresin[J].WatRes,1996,30:1749～1758.[3]ElisabethN,JanR,RafD,etal.Advancedsludgetreatmentaffectsextracellularpolymericsubstancestoimproveactivatedsludgedewatering[J].JHazardMat,2004,106B:83～92.[4]MagaraY,NumbuS,UtosawaK.Biochemicalandphysicalpropertiesofanactivatedsludgeonsettlingcharacteristics[J].WatRes,1986,10(1):71～77.[5]SaninFD,VesilindPA.Effectofcentrifugationontheremovalofextracellularpolymersandphysicalpropertiesofactivatedsludge[J].WatSciTech,1994,30(8):117～127.[6]KangSM,KishimotoM,ShioyaS,etal.Dewateringcharacteristicsofactivatedsludgesandeffectofextracellularpolymer[J].JFermentBioeng,1989,68(2):117～122.[7]HoughtonJI,QuarmbyJ,StephensonT.Municipalwastewatersludgedewaterabilityandthepresenceofmicrobialextracellularpolymer[J].WatSciTech,2001,44:373～379.[8]GoodwinJAS,ForsterCF.Afurtherexaminationintothecompositionofactivatedsludgesurfacesinrelationtotheirsettlementcharacteristics[J].WatRes,1985,19:527～533.[9]ChaoAC,KeinathTM.Influenceofprocessloadingintensityonsludgeclari