DRINKING WATER TREATMENT SLUDGE PRODUCTIONAND DEWATERABILITY David Ignatius Verrelli BA, BE(Chemical) Hons. (Monash) Submitted in total fulfilment of the requirements of the degree of Doctor of Philosophy November 2008 Particulate Fluids Processing Centre Department of Chemical & Biomolecular Engineering The University of Melbourne DrinkingWaterTreatmentSludgeProductionandDewaterabilityDavidIgnatiusVerrelli D.I.VerrelliMelbourne NationalLibraryofAustraliaCataloguinginPublicationentryAuthor: Verrelli,DavidIgnatius,1977Title: Drinkingwatertreatmentsludgeproductionanddewaterability/DavidIgnatiusVerrelli.ISBN: 9780980629705(hbk.)9780980629712(pbk.)Notes: Bibliography.Subjects: DrinkingwaterPurification.WaterPurification.Watertreatmentplantresiduals.WatertreatmentplantsWastedisposal.WatertreatmentplantresidualsManagement.DeweyNumber: 628.162 ISBN9780980629705 (hardboundin2volumes) ISBN9780980629712 (softboundin2volumes) ISBN9780980629729 (PDF,singlele)D.I.VerrelliNovember2008,March2009Copying,scanningandprintingarepermittedforpersonalandapproveduses.The authors moral rights are asserted. Printedonpermanent(acidfree)paperi SUMMARY The provision of clean dr i nki ng wat er typically involves t r eat ment processes toremove contaminants. The conventional process involves coagulation with hydrolysingmetal salts, typically of aluminium (alum) or trivalent iron (ferric). Along with theproduct water this also produces a waste byproduct, or s l udge. The fact of increasingsludge pr oduc t i on due to higher levels of treatment and greater volume of watersupplyconictswithmoderndemandsforenvironmentalbestpractice,leadingtohighernancial costs. A further issue is the signicant quantity of water that is held up in thesludge,andwasted.Onemeansofdealingwiththeseproblemsistodewaterthesludgefurther.Thisreducesthevolumeofwastetobedisposedof.Theconsistencyisalsoimproved(e.g.forthepurposeoflandlling). And a signicant amount of water can be recovered. The eciency, andecacy,ofthisprocessdependsonthe dewat er abi l i t yofthesludge.In fact, good dewaterability is vital to the operation of conventional drinking watertreatment plants (WTPs). The usual process of separating the particulates, formed from ablend of contaminants and coagulated precipitate, relies on clarication and thickening,whichareessentiallysettlingoperationsofsolidliquidseparation.WTP operators and researchers do attempt to measure sludge dewaterability, butusually rely on empirical characterisation techniques that do not tell the full story and caneven mislead. Understanding of the physical and chemical nature of the sludge is alsosurprisinglyrudimentary,consideringthelonghistoryoftheseprocesses.The present work begins by reviewing the current state of knowledge on raw water andsludge composition, with special focus on solid aluminium and iron phases and on fractalaggregate structure. Next the theory of dewatering is examined, with the adoptedphenomenologicaltheorycontrastedwithempiricaltechniquesandothertheories.D. I. VERRELLI ii The foundation for subsequent analyses is laid by experimental work which establishes thesolid phase density of WTP sludges. Additionally, alum sludges are found to containpseudobhmite,while2lineferrihydriteandgoethiteareidentiedinferricsludges.Akeyhypothesisisthatdewaterabilityispartlydeterminedbythetreatmentconditions.Toinvestigatethis,numerousWTPsludgeswerestudiedthathadbeengeneratedunderdiverseconditions: some plant samples were obtained, and the remainder were generated in thelaboratory (results were consistent). Dewaterability was characterised for each sludge inconcentration ranges relevant to settling, centrifugation and ltration using modelsdeveloped by LANDMAN and WHITE interalia; it is expressed in terms of both equilibriumandkineticparameters,py()andR()respectively.Thisworkconrmedthatdewaterabilityissignicantlyinuencedbytreatmentconditions.ThestrongestcorrelationswereobservedwhenvaryingcoagulationpHandcoagulantdose.At high doses precipitated coagulant controls the sludge behaviour, and dewaterability ispoor. Dewaterability deteriorates as pH is increased for highdose alum sludges; othersludges are less sensitive to pH. These ndings can be linked to the faster coagulationdynamicsprevailingathighcoagulantandalkalidose.Alumandferricsludgesingeneralhadcomparabledewaterabilities,andthecharacteristicsofamagnesiumsludgeweresimilartoo.Smalleectsondewaterabilitywereobservedinresponsetovariationsinrawwaterorganiccontent and shearing. Polymer occulation and conditioning appeared mainly to aectdewaterability at low sludge concentrations. Ageing did not produce clear changes indewaterability.Dense,compactparticlesareknowntodewaterbetterthanuyaggregatesorocsusuallyencountered in drinking water treatment. This explains the superior dewaterability of asludge containing powdered activated carbon (PAC). Even greater improvements wereobservedfollowingacycleofsludgefreezingandthawingforawiderangeofWTPsludges.Further aspects considered in the present work include deviations from simplifyingassumptions that are usually made. Specically: investigation of longtime dewateringbehaviour,walleects,nonisotropicstresses,andreversibilityofdewatering(orelasticity).DRINKING WATER TREATMENT SLUDGE PRODUCTION AND DEWATERABILITY iii Several other results and conclusions, of both theoretical and experimental nature, arepresented on topics of subsidiary or peripheral interest that are nonetheless important forestablishingareliablebasisforresearchinthisarea.This work has proposed links between industrial drinking water coagulation conditions,sludge dewaterability from settling to ltration, and the microstructure of the aggregatesmaking up that sludge. This information can be used when considering the operation ordesign of a WTP in order to optimise sludge dewaterability, within the constraints ofproducingdrinkingwaterofacceptablequality.Keywor ds ageing; aggregates; aluminium sulfate; centrifugation; coagulation; creep; delayedsettling; dewatering; elasticity; ferric chloride; ltration; occulation; ocs; fractaldimension; freezethaw conditioning; longtime behaviour; magnesium sulfate; naturalorganicmatter;polymer;powderedactivatedcarbon;reversibility;settling;sludge;shear;walleects;water.I ndi cat i vet r ansl at i onsof t i t l e Trinkwasseraufbereitung:ErzeugungundEntwsserungsfhigkeitdesSchlammesTrattamentodelleacquepotabili:LagenerazioneelafacilitdidisidratazionedelfangoTratamientodeaguaspotables:LageneracinylafacilidaddedeshidratacindefangosTraitement de leau potable: La formation et la facilit de dshydratation des boues(schlamms) () BehandlingafDrikkevand,SlamProduktionogEvneTilatAfvande[cf.DrikkevandBehandling,SlamProduktionogAfvanding]v DECLARATION Thisistocertifythat:1.the thesis comprises only my original work towards the Ph.D., except whereindicatedinthePreface&Acknowledgements;2.dueacknowledgementhasbeenmadeinthetexttoallothermaterialused;and3.the thesis is approximately 130000 words in length, exclusive of tables, maps,bibliographiesandappendices.DavidIgnatiusVerrellivii PREFACE This work was initiated as part of a project carried out as a collaboration between TheUniversityofMelbourne,UnitedUtilities(U.K.),andYorkshireWater(U.K.).Ienteredthiscourseofstudywiththedualaimsoffurtheringmyownknowledgeandskills,and arriving at research outcomes that have real application. The topic of drinking watertreatment sludge dewatering does indeed have a direct relevance to industry, and thusindirectlyaectsthecommunity.Ihavelearnedagreatdealinmyresearch,andhopethatmyndingswillfallonreceptiveears.It has traditionally been the duty of academics and Ph.D. candidates to challenge acceptedwisdom. Various pressures combine to discourage these enquiries. Too frequent and toogreat is the temptation to take the expedient path of accepting, without question, theestablished doctrine of the day. Examples include use of A400nm to estimate true colour, thederivation(s)ofTERZAGHIshydraulicdiusionequation,omissionofCORIOLISforces,useofnominal S values, description of alum and ferric precipitates as Al(OH)3 and Fe(OH)3, theirreversibility of dewatering, description of dewaterability with only D(), conation of Dfwith internal aggregate structure, and belief that smaller Df guarantees smaller agg (allelucidatedherein).I have been fortunate to have had the implicit support of my supervisors to correct thesefundamentalerrors.IwouldparticularlyliketothankPeterScalesforhispatience.ix ACKNOWLEDGEMENTS This work was carried out under the supervision of Prof. Peter J. Scales & Dr. David R.Dixon.Theyhaveaddedconsiderableexpertiseandexperiencetotheproject.This work would not have been possible without the assistance of postdoctoral researchfellows Dr. Shane P. Usher & Dr. Ross G. de Kretser. It is rare to nd a technical problemtheyareunabletoresolve.IwouldalsoliketoacknowledgethefellowshipoftheothermembersoftheScalesresearchgroup, past and present. While it is not possible to list them all individually, it would beremissnottomentionRachaelC.Wall,RudolfSpehar,HemadriK.SahaandAinulA.b.A.Aziz.NumerousothermembersoftheDepartmentofChemicalandBiomolecularEngineering,theParticulate Fluids Processing Centre, the School of Engineering, and the university as awhole have supported this work, either directly or indirectly. This includes students,generalsta,andacademics.Particularmentionshouldbemadeof:theworkshopstaKevin Smeaton and team; the analytical facility Ernest H. Gutsa; the SEM imagingfacilityRogerC.A.Curtain;theadministrativesta;andthelibrarysta.Access to equipment was facilitated by G. W. Stevens (spectrophotometer) and M.Ashokkumar (TOC). S. E. Kentish and her group generously gave up laboratory space toaccommodatemywork.Discussions with L. R. White, T. W. Healy, R. J. Eldridge, G. V. Franks, P. Liovic, P. S.Grassia, E. K. Hill, F. Grieser, W. A. Ducker, and B. Jeerson are appreciated, as arecorrespondence with V. J. Blue, J. Bellwood, E. M. Furst, R. Simard & P. LEcuyer, R. M. L.Evans, J.P. Jolivet, W. R. Knocke, and J. H. Kwon. Assistance from Ina Ritsner with aRussiantextisalsogratefullyacknowledged.ThankstoJamesTardioforhelpingtovalidateTOCresults.IalsorecognisePeterJarvissgenerosityinprovidingaccesstohiscollectionofarticlesfromtheliterature.ThankstoNathanMattesonfortypographytips.D. I. VERRELLI x United Utilities and Yorkshire Water provided project sponsorship, with particular supportfromDr.MartinTillotsonandDr.PeterHillis.The Australian Research Council and The University of Melbourne provided funds for apostgraduatescholarship.MelbourneWater(C.Barberet alii),theCooperativeResearchCentreforWaterQualityandTreatment (G. Newcombe etalia), United Utilities Australia (L. Choy etalii), and UnitedWater (D. Becker etalii), and Ciba Specialty Chemicals (J. Bellwood) are acknowledged forassistanceinobtainingsamples.Research does not always run smoothly, and I want to make especial acknowledgement ofAliciaforhercompanionship.Evenwhenresearchdoesrunsmoothly,itisgoodtobeabletotakeabreaknowandagain,andspendtimewithfriends.ThepathIhavetakenthroughtheeducationsystemhasformedthefoundationuponwhichthese studies have been built, and I trust reects favourably upon Waverley Meadows P.S.,WheelersHillS.C.,andMonashUniversity(Clayton)asidefrommycurrentinstitution.Finally, my parents, Vince & Virginia, instilled in me an appreciation for knowledge andlearning,andsupportedmecontinuouslythroughoutmyeducation,aswellasathome,forwhichIamgrateful.Alongwithmysupervisors,theyalsoassistedbyproofreadingthetext.xi OVERVIEW OF CONTENTS 1. I NTRODUCTI ON . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12. BACKGROUND. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 573. EXPERI MENTAL METHODS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1574. SOLI D PHASE ASSAYS AND DENSI TI ES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2535. EFFECT OF COAGULANT TYPE, DOSE, AND pH . . . . . . . . . . . . . . . . . . . . 3016. EFFECT OF RAW WATER QUALI TY. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3597. EFFECT OF SHEAR AND POLYMER ADDI TI ON . . . . . . . . . . . . . . . . . . . . . 3758. EFFECT OF UNUSUAL TREATMENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4339. UNUSUAL MATERI AL BEHAVI OUR. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46910. OUTCOMES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54311. BI BLI OGRAPHY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 559APPENDI CES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 619REVI EW . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 621SUPPORTI NG MATERI AL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 825D. I. VERRELLI xii DRINKING WATER TREATMENT SLUDGE PRODUCTION AND DEWATERABILITY xiii DETAILED CONTENTS SUMMARY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . i Keywords.......................................................................................................................... iiiIndicativetranslationsoftitle ........................................................................................ iiiDECLARATI ON . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vPREFACE. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vi i ACKNOWLEDGEMENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . i xFI GURES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xxi xTABLES. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xxxi xNOMENCLATURE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xl i i i Symbols . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xl i i i Latinsymbols............................................................................................................................ xliiiGreeksymbols.........................................................................................................................xlviiiCyrillicsymbols ............................................................................................................................. lMathematicaloperatorsandothersymbols ............................................................................. liSuperscripts................................................................................................................................... liSubscripts...................................................................................................................................... liiAbbrevi ati ons . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . l i i i Terminol ogy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . l vD. I. VERRELLI xiv 1. I NTRODUCTI ON . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111 Dri nking water producti on processes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112 Sl udge producti on. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 713 Sl udge transportation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 914 Sl udge dewatering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11141 Claricationandthickening.......................................................................................13142 Naturaldewatering.....................................................................................................15143 Centrifugation..............................................................................................................18144 Filtration........................................................................................................................201441 Filterpresses.........................................................................................................201442 Beltlterpresses..................................................................................................221443 Vacuumdrumlters ...........................................................................................231444 Otherlters...........................................................................................................2415 Sl udge disposal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24151 Overviewofdisposalroutes ......................................................................................26152 Dischargetoanaturalwaterbody............................................................................28153 Dischargetosewer ......................................................................................................31154 Dischargetolagoons...................................................................................................34155 Wastelandll ...............................................................................................................36156 Engineeringll.............................................................................................................40157 Landapplication,includingagriculturaluses.........................................................411571 Regulatoryissues.................................................................................................45158 Chemicalreuse.............................................................................................................47159 Otherbenecialuses ...................................................................................................4916 The nexus between sl udge generati on, sludge dewateri ng, andsl udge di sposal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5117 Ai m of thi s work . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52DRINKING WATER TREATMENT SLUDGE PRODUCTION AND DEWATERABILITY xv 2. BACKGROUND. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5721 Introduction to dewateri ng . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58211 Solidosity ......................................................................................................................59212 Dewateringregimes ....................................................................................................60213 Thedewateringspectrum ........................................................................................62214 Drivingforcesandresistancestodewatering.......................................................64215 Packing..........................................................................................................................6722 Sl ow parti cl e moti on . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6823 Fl ow through porous medi a . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71231 DARCYslaw .................................................................................................................71232 ExtensionsandalternativestoDARCYslaw............................................................7524 Dewatering anal ysi s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76241 Empiricalmethods ......................................................................................................782411 Compressibility....................................................................................................82Isothermalcompressibility..............................................................................................82Extensiontoparticulatesystems....................................................................................82Coecientofvolumecompressibility...........................................................................84Reciprocalconnedelasticmodulus ...........................................................................85Compressibilitycoecients............................................................................................862412 Zonesettlingrate .................................................................................................862412(a) Denitionofzonesettling.............................................................................862412(b) Measurement ..................................................................................................872413 Capillarysuctiontime(CST)andderivatives .................................................882414 Specicresistancetoltration(SRF).................................................................902414(a) AdjustedSRF ..................................................................................................912415 Otherad hocmethods ..........................................................................................92242 Earlydewateringtheory.............................................................................................93243 KinematicalbatchsettlingtheoryofKYNCH ...........................................................932431 Shockthickness ....................................................................................................952432 Polydispersesuspensionsandinstability ........................................................962433 InuenceofBROWNianmotion..........................................................................99D. I. VERRELLI xvi 244 Permeationtheoriesofsettlingandltration........................................................100245 PhenomenologicaldewateringtheoryofLANDMAN,WHITEet alia ...................1042451 Modelparameters..............................................................................................1052451(a) Compressiveyieldstress.............................................................................106Systemanisotropyandosmosis ..................................................................................107Empiricalandmodelfunctionalformsofpy() ........................................................109Creepeectsatlowstresses.........................................................................................109Elasticbehaviour ...........................................................................................................1112451(b) Hinderedsettlingparameters ..................................................................111EmpiricalandmodelfunctionalformsofR() .........................................................1132451(c) Dynamiccompressibility ............................................................................1132451(d) Solidsdiusivity...........................................................................................1162452 Generalequations..............................................................................................1172453 Batchsettling......................................................................................................1192453(a) Earlytime ......................................................................................................1192453(b) Generalequation ..........................................................................................1212453(c) Practicalsolution..........................................................................................1222453(d) Settlinginrealsystems ................................................................................1262453(e) Idealsettling..................................................................................................1282453(f) Multipletesttheory .....................................................................................1292453(g) Longtimebehaviour ...................................................................................1322454 Batchcentrifugation ..........................................................................................1332454(a) Comprehensiveanalysis .............................................................................1342454(b) Simpliedonedimensionalanalysis.........................................................1402455 Permeation..........................................................................................................1432456 Filtration..............................................................................................................144246 Othercontinuummodels .........................................................................................151247 Fundamentalmechanistictheory............................................................................1512471 Micromechanicaldependenceofyieldstressond0 ......................................152248 Stochasticanalysis .....................................................................................................155DRINKING WATER TREATMENT SLUDGE PRODUCTION AND DEWATERABILITY xvii 3. EXPERI MENTAL METHODS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15731 Treatment parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15732 Experi mental materi al s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 161321 Puriedwater.............................................................................................................161322 Rawwater...................................................................................................................161323 Coagulants..................................................................................................................1643231 Magnesium.........................................................................................................164324 Alkali ...........................................................................................................................1663241 Hydrolysisratio.................................................................................................166325 Polymers .....................................................................................................................168326 Plantandpilotplantsludges ...................................................................................1683261 Winneke ..............................................................................................................1683262 Macarthur ...........................................................................................................1693263 HappyValley .....................................................................................................17133 Sl udge generation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 172331 Industrialpractice......................................................................................................172332 Scalingbyvelocitygradient .....................................................................................1733321 Standardtankconguration..........................................................................174333 Jartestrig(optimaldoseselection).........................................................................1783331 Mechanicalconstructionandoperation.........................................................1783332 Identifyingtheoptimum..................................................................................180334 Tank.............................................................................................................................181335 Reproducibility ..........................................................................................................185336 pH................................................................................................................................18534 Treatment characteri sati on. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 186341 Absorbance.................................................................................................................1863411 Procedure............................................................................................................1873412 Spectra.................................................................................................................1883413 Singlewavelengths............................................................................................188342 Truecolour .................................................................................................................190D. I. VERRELLI xviii 3421 Spectrophotometricdetermination.................................................................1913421(a) Estimationfromsinglewavelengthabsorbance......................................193343 Turbidity.....................................................................................................................1943431 Measurement......................................................................................................1943432 Experimental ......................................................................................................195344 Dissolvedorganiccarbon(DOC) ............................................................................196345 Totalsolidsanddissolvedsolids.............................................................................200346 Conductivity...............................................................................................................20035 Sl udge characterisati on compressional rheology . . . . . . . . . . . . . . . . . . . . . . . . 202351 Batchsettling..............................................................................................................2023511 Temporaldata(singletest)...............................................................................2033511(a) Reproducibility.............................................................................................2033512 Equilibriumdata(multipletest) ......................................................................2053513 Accuracy .............................................................................................................206352 Batchcentrifugation..................................................................................................2073521 Prethickening....................................................................................................2083522 Acceleratedsettling...........................................................................................2083522(a) Results............................................................................................................211Reproducibility ..............................................................................................................2203522(b) Implications...................................................................................................221353 Deadendltration....................................................................................................2223531 Steppedpressureanalysis ................................................................................2233531(a) Reproducibility.............................................................................................2243532 Permeation..........................................................................................................2283533 Improvementsmadetomethodology............................................................2303533(a) Rigdesignandoperation............................................................................2303533(b) Dataprocessingandanalysis .....................................................................2333534 Keyinterferences ...............................................................................................2333534(a) Temperature..................................................................................................2333534(b) Violationofonedimensionaldewateringassumption ..........................235354 Reproducibility ..........................................................................................................239DRINKING WATER TREATMENT SLUDGE PRODUCTION AND DEWATERABILITY xix 36 Sl udge characterisati on shear yiel d stress . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 243361 Conventionalsubaerialslumptests........................................................................245362 Proposedsubaqueousslumptest............................................................................24637 Model l ing of uni t operati ons . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 249371 Gravitysettlingandcentrifugation.........................................................................249372 Filtration......................................................................................................................2494. SOLI D PHASE ASSAYS AND DENSI TI ES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25341 Publ i shed data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 255411 Massbalanceofsludgegeneration .........................................................................255412 Purecomponentdensities ........................................................................................259413 WTPsludgedensities................................................................................................2634131 Bulkdensities .....................................................................................................2634132 Solidphasedensities .........................................................................................26442 Experi mental determi nation of composi ti on . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 267421 Method........................................................................................................................2684211 Energydispersivespectrometry(EDS) ..........................................................2684211(a) Samples..........................................................................................................2684212 Xraydiraction(XRD).....................................................................................2694212(a) Theory............................................................................................................2694212(b) Referencedata...............................................................................................2704212(c) Equipment .....................................................................................................2724212(d) Samples..........................................................................................................272422 Results .........................................................................................................................2754221 Energydispersivespectrometry(EDS) ..........................................................2754222 Xraydiraction(XRD).....................................................................................2804222(a) Aluminium....................................................................................................2804222(b) Iron .................................................................................................................282423 Discussion...................................................................................................................285424 Conclusions ................................................................................................................286D. I. VERRELLI xx 43 Experi mental density determinati on. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 287431 Method........................................................................................................................2874311 Equipment ..........................................................................................................289432 Results .........................................................................................................................2904321 Liquidphase.......................................................................................................2904322 Solidphase..........................................................................................................291433 Modelcurves..............................................................................................................295434 Discussion...................................................................................................................296435 Conclusions ................................................................................................................2995. EFFECT OF COAGULANT TYPE, DOSE, AND pH . . . . . . . . . . . . . . . . . . . . 30151 Publ i shed observations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 301511 Eectofdose ..............................................................................................................301512 EectofpHandhydrolysisratio............................................................................3025121 Aluminium.........................................................................................................3035122 Iron.......................................................................................................................3055123 Magnesium.........................................................................................................306513 Eectofcoagulant .....................................................................................................30652 Materi als and methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30853 Al um sl udges: vari ati on of dose . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 311531 Resultsanddiscussion..............................................................................................3115311 IntermediatepH(6) ...........................................................................................3115312 High(8)andlow(5)pH ................................................................................314532 Conclusions ................................................................................................................31654 Al um sl udges: vari ati on of pH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 317541 Resultsanddiscussion..............................................................................................317542 Conclusions ................................................................................................................32155 Al um sl udges: combi ned dosepH effects. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32156 Al um sl udges: compari son wi th pl ant and pi l ot pl ant data . . . . . . . . . . . 330561 WinnekeWTP ............................................................................................................330DRINKING WATER TREATMENT SLUDGE PRODUCTION AND DEWATERABILITY xxi 562 HappyValleypilotplant ..........................................................................................330563 Otherplants................................................................................................................33457 Ferri c sl udges: variati on of dose and pH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 335571 Experimental ..............................................................................................................335572 Resultsanddiscussion..............................................................................................337573 Conclusions ................................................................................................................34058 Ferri c sl udges: comparison wi th plant data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 341581 MacarthurWFP..........................................................................................................341582 Otherplants................................................................................................................34259 Compari son of al um and ferri c sl udges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 343591 Compressiveyieldstressandhinderedsettlingfunction ...................................343592 DARCYslawpermeability,KD .................................................................................345593 Solidsdiusivity........................................................................................................346510 Industri al i mpl i cations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 351511 Magnesi um sl udge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3525111 Experimental ..............................................................................................................3535112 Results .........................................................................................................................3545113 Discussion...................................................................................................................3565114 Conclusions ................................................................................................................3576. EFFECT OF RAW WATER QUALI TY. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35961 Publ i shed observations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 359611 NOMisbenecial ......................................................................................................360612 NOMhasnosignicanteect .................................................................................360613 NOMisdetrimental ..................................................................................................360614 NOMhasamixedeect ...........................................................................................36262 Experi mental . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 363621 DialysedMIEXeluate(dMIEX)...........................................................................363622 Sludges ........................................................................................................................365D. I. VERRELLI xxii 63 Resul ts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36764 Di scussi on. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37165 Concl usi ons . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3737. EFFECT OF SHEAR AND POLYMER ADDI TI ON . . . . . . . . . . . . . . . . . . . . . 37571 Previ ous i nvesti gati ons and experi ence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 376711 Polymeraddition.......................................................................................................376712 Shear ............................................................................................................................3787121 Duringformation...............................................................................................3787122 Afterformation,beforesettling.......................................................................3837123 Afterformationandsettling ............................................................................38572 Shear duri ng coagulati on . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 387721 Materialsandmethods .............................................................................................388722 Results .........................................................................................................................389723 Discussionandconclusions .....................................................................................39173 Fl occul ation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 392731 Materialsandmethods .............................................................................................392732 Results .........................................................................................................................394733 Discussionandconclusions .....................................................................................39674 After settl i ng: shear and pol ymer conditi oning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 397741 Methodology..............................................................................................................3987411 Materials .............................................................................................................3987412 Dosesettingbycapillarysuctiontime(CST).................................................4007413 Shearandmixingrig.........................................................................................4017414 Characterisation.................................................................................................407742 Polymerdoseselection .............................................................................................408743 Preliminaryndings .................................................................................................410744 Optimisation,error/sensitivityanalysis,andcalibrationandvalidation..........4147441 Optimisation.......................................................................................................4147442 Error/sensitivityanalysis..................................................................................415DRINKING WATER TREATMENT SLUDGE PRODUCTION AND DEWATERABILITY xxiii 7442(a) Subsetselection ...........................................................................................4157442(b) Experimentalandttingerrors..................................................................4177443 Calibrationandvalidation ...............................................................................4207443(a) Approach.......................................................................................................4207443(b) ModeratepHsludges ..................................................................................4217443(c) HighpHsludges ..........................................................................................424745 Principalresults .........................................................................................................425746 Discussion...................................................................................................................429747 Conclusions ................................................................................................................4318. EFFECT OF UNUSUAL TREATMENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43381 Agei ng . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 433811 Reportedeects .........................................................................................................433812 Experimentalmethods..............................................................................................435813 Results .........................................................................................................................438814 Discussion...................................................................................................................443815 Conclusions ................................................................................................................44582 Freezethaw condi ti oni ng . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 445821 Background ................................................................................................................4458211 Mechanism..........................................................................................................4468212 Operationalparameters....................................................................................4498213 Improvementstodewaterability.....................................................................4548214 Industrialapplication........................................................................................455822 Experimentalmethods..............................................................................................456823 Experimentalresults .................................................................................................457824 Discussionandconclusions .....................................................................................46183 Powdered acti vated carbon (PAC) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 462831 Reportedeects .........................................................................................................462832 Equipment ..................................................................................................................463833 Materials .....................................................................................................................463D. I. VERRELLI xxiv 834 Experimentalresults .................................................................................................464835 Discussionandconclusions .....................................................................................4669. UNUSUAL MATERI AL BEHAVI OUR. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46991 Inducti on ti me . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 469911 Publishedobservationsandtheories......................................................................4699111 Delayedsettling .................................................................................................4709111(a) Delayduetochannelling ............................................................................4719111(b) Delayduetodensication ..........................................................................4769111(c) Delayduetowalleects .............................................................................4799112 Deterministicchaos:selforganisedcriticalityandperiodicity..................480912 Practicalrelevanceandanalysis ..............................................................................482913 Experimentalndings...............................................................................................48392 Wal l effects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 486921 Cylinderdiameter......................................................................................................4869211 Previousrecommendations..............................................................................4879211(a) Torpidmatter................................................................................................4889212 Presentndings .................................................................................................4909212(a) Settling...........................................................................................................4909212(b) Filtration ........................................................................................................492922 Cylindersurfaceproperties......................................................................................4939221 Experimental ......................................................................................................4939222 Resultsanddiscussion......................................................................................493923 Conclusions ................................................................................................................49693 Longtime dewateri ng behaviour . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 497931 Ageingandbiologicalactivityduringexperiment...............................................4989311 Observedbiologicalactivity.............................................................................4989312 Developmentoflargescalemorphology.......................................................4999313 Exposuretolight................................................................................................5019314 Conclusions ........................................................................................................502DRINKING WATER TREATMENT SLUDGE PRODUCTION AND DEWATERABILITY xxv 932 Creepandlongtimemetastability..........................................................................5039321 Postulatedbehaviour ........................................................................................5039322 Settling.................................................................................................................5049323 Filtration..............................................................................................................5119324 Discussion...........................................................................................................5159324(a) Bulkviscositytheory....................................................................................5179324(b) Thermallyactivatedbarrierhoppingtheory ...........................................5189325 Nondiusiveprocesses ...................................................................................519933 Conclusions ................................................................................................................51994 Reversi bi li ty: El astic cake reexpansion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 521941 Literaturereports.......................................................................................................523942 Elasticitytheory .........................................................................................................529943 Methodology..............................................................................................................537944 Results .........................................................................................................................538945 Discussionandconclusions .....................................................................................54110. OUTCOMES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 543101 Concl usi ons . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5431011 Theoretical ..................................................................................................................5431012 Experimental ..............................................................................................................546102 Industri al i mpl i cations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 552103 Further work . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5531031 Experimental ..............................................................................................................5531032 Theoreticaldevelopment ..........................................................................................555104 Cl osing remarks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55711. BI BLI OGRAPHY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 559D. I. VERRELLI xxvi APPENDI CES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 619REVI EW . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 621R1. CONDI TI ONS AFFECTI NG THE NATURE OF THE SLUDGEMATERI AL FORMED . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 627R11 Important consti tuents of raw water natural organi c matter(NOM) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 627R12 Coagul ation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 640R13 Fl occul ation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 704R14 Mi xi ng . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 715R15 Aggregate structure and fractal di mensi on. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 735R2. BEHAVI OUR OF SLUDGE LI KE MATTER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 791R21 Endogenous syneresi s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 791R22 Geomechani cs and creep . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 799R23 Macrorheol ogi cal models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 814DRINKING WATER TREATMENT SLUDGE PRODUCTION AND DEWATERABILITY xxvii SUPPORTI NG MATERI AL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 825S1. EARLY DEWATERI NG THEORY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 831S2. GENERAL PRI NCI PLES OF KI NEMATI C WAVES . . . . . . . . . . . . . . . . . . . . 834S3. EXPERI MENTAL OBSERVATI ONS OF LONG TI MESETTLI NG . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 836S4. DOUBLE EXPONENTI AL VERSI ON OF LONG TI MEFI LTRATI ON ASYMPTOTE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 840S5. STOCHASTI C SETTLI NG ANALYSI S . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 841S6. J AR TESTI NG PRACTI CE. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 843S7. LI GHT ABSORBANCE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 848S8. COLOUR MEASUREMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 856S9. EVALUATI ON AND SELECTI ON OF SYRI NGE FI LTERS . . . . . . . . . 867S10. MULTI PLE BATCH SETTLI NG ANALYSI S . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 874S11. SLUMP TEST RESULTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 892S12. CONTOUR SENSI TI VI TY ANALYSI S . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 895S13. FI LTER PRESS MODELLI NG . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 898D. I. VERRELLI xxviii S14. POLYMER CONDI TI ONER MI XI NG RECOMMENDATI ONOF WRc . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 908S15. BOOTSTRAP AND J ACKKNI FE STATI STI CS . . . . . . . . . . . . . . . . . . . . . . . . . . 913S16. SI LANI SATI ON . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 925S17. BULK VI SCOSI TY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 928S18. BARRI ER HOPPI NG THEORY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 941S19. FI LTRATI ON RI G FRAME EXPANSI ON. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 943S20. ESTI MATI ON OF THE BULK MODULUS OFCOMPRESSI BI LI TY, BS, THROUGH CENTRI FUGATI ON. . . . . . . . . 945S21. METAL COMPLEXATI ON BY FOREI GN ANI ONS . . . . . . . . . . . . . . . . . 947S22. PSEUDOBHMI TE STRUCTURE AND COMPOSI TI ON . . . . . . . . . . . 954S23. OCCURRENCE OF I RON( I I ) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 956S24. RELATI VE STABI LI TY OF HMATI TE AND GOETHI TE . . . . . . . . 957S25. CORRELATI ONS OF dm a x . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 960S26. ESTI MATI ON OF G FOR I NDUSTRI AL SCENARI OS. . . . . . . . . . . . . . . 964TheReviewandSupportingMaterialappendiceseachbeginwitha det ai l edlistingoftheircontents.DRINKING WATER TREATMENT SLUDGE PRODUCTION AND DEWATERABILITY xxix FIGURES Figure11:DistributionofrawwatersourcesandtreatmentsinEnglandandWalescirca1997,bywatervolume[315].............................................................................................................................. 2Figure12:Indicativeowchartofconventionalwatertreatmentprocesswithgravitysettling,includingsludgeprocessingoperations. ............................................................................................... 5Figure13:U.K.landlltaxratessinceinception[53, 70, 72, 315].............................................................. 38Figure21:Simpliedschematicofhypotheticalequilibriumparticlepackingresultingfromsequentialapplicationofaxialandlateralstresses. ......................................................................... 108Figure22:Typicaluxplot[cf.205],showingkeyfeaturesofthesettlinguxfunction,Sq (),andillustratingtherangeofsolidositiesforwhichR()canbeanalyticallyevaluatedforagiveninitialsolidosityof0or0:therangeisthesame,asmaterialloadedat0jumpsdirectlyto0[cf.652].Nottoscale.................................................................................................... 123Figure23:Schematicrepresentationoftypicalbatchsettlingbehaviourwith0g[495]. .............. 128Figure25:Schematicofcentrifugesystem,lookingdownonplaneofrotation.Gravityisassumedtoactinthezdirection....................................................................................................... 135Figure26:Interfacesettlingratesof cent ri f ugedsamples.(Thetwoalternativesgivenforeachsludgetyperefertothelocalformofh(t)assumedinnumericallyestimatingthederivative.) ............................................................................................................................................. 138Figure31:Rangeofalumsludgescharacterised. ...................................................................................... 158Figure32:Rangeofferricsludgescharacterised. ...................................................................................... 159Figure33:Locationofalumandferricsludgegenerationconditionswithrespecttothealuminiumandiron(III)solubilitycurves.PlantAlincludesthepilotplantsludges............ 160Figure34:Experimentalhydrolysisratiosforalumcoagulation,[OH]added/[Al].Thesolubilityenvelopeisindicatedbythedashedlines. ........................................................................................ 167Figure35:SchematicofHOLLAND&CHAPMANs[485]standardtankconguration. ...................... 176Figure36:Large(53.5L)mixingvesselbasedonstandardtankconguration................................... 182Figure37:Largescalecoagulationequipment. ......................................................................................... 183Figure38:TransientpHprolesforveconsecutiveferrictreatmentsat80mg(Fe)/LcarriedoutonWinnekerawwatercollected20040915. ............................................................................. 186Figure39:Compressiveyieldstresscurvescomputedfromsevenbatchsettlingtests.Centrifugationandltrationdataalsoshown.................................................................................. 204Figure310:Hinderedsettlingfunctioncurvescomputedfromsevenbatchsettlingtests.Filtrationdataalsoshown. .................................................................................................................. 204Figure311:Compressiveyieldstressdeterminedrstwithoutcentrifugationdata,andthenwithcentrifugationdata,foralaboratoryandaplantalumsludge.............................................. 212D. I. VERRELLI xxx Figure312:Compressiveyieldstressdeterminedrstwithoutcentrifugationdata,andthenwithcentrifugationdata,foralaboratoryandaplantferricsludge. ............................................ 213Figure313:Hinderedsettlingfunctioncomputedwithandwithoutcentrifugationdataforalaboratoryandaplantalumsludge. .................................................................................................. 215Figure314:Hinderedsettlingfunctioncomputedwithandwithoutcentrifugationdata.Revisedtsusingcentrifugationdatawereobtainedonlybyadjustingpy()asinFigure311. ......................................................................................................................................................... 216Figure315:Predictedcentrifugationh(t)proles.Thepredictionforthepy()andR()curvesobtainedwithoutcentrifugationdataisforcomparisononly.Therstimprovedtwasobtainedusingtheadjustedpy()curvefromFigure311,andthiswasoptimisedtoyieldthesecondimprovedpredictionbyiterativelyadjustingR()toyieldthecurveshowninFigure313. ........................................................................................................................................ 219Figure316:Predictedgravitysettlingh(t)proles.Therstpredictionusespy()andR()curvesobtainedwithoutcentrifugationdata.Thesecondpredictionwasobtainedusingtheadjustedpy()curvefromFigure311.ThenalpredictionwasobtainedbyiterativelyadjustingR()(seeFigure313)tooptimisethepredictedcentrifugationh(t)prole(seeFigure315)........................................................................................................................ 220Figure317:Schematicoflaboratoryltrationrig. ..................................................................................... 222Figure318:Duplicatecompressiveyieldstressmeasurementsfromsteppedpressureltration. .... 226Figure319:Hinderedsettlingfunctionestimatesfromduplicatesteppedpressurepermeabilityruns,basedon averageofpy()measurements. ............................................................................ 227Figure320:(a)Theperiodfrom500to1700secondsshowstheclosecontrolofsamplepressureattainableusingautomaticcontrolwhentherateofdewateringisnottoohigh.(b)theperiodfrom340to370secondsshowsthelevelofcontrolachievableusingmanualcontrolwhentherateofdewateringishigh..................................................................... 229Figure321:Thermalcyclinginltration.160mg(Fe)/Lsludgelteredonneweraluminiumframedrig. ............................................................................................................................................ 234Figure322:Schematicofcakeunloadedfromltrationrigshowingcreviceintopsurfaceandnonstraightsideprole.Thesefeatureswerepresentinaminorityofcases............................. 239Figure323:Compressiveyieldstressdataforreplicatealumsludgesamples. .................................... 242Figure324:Hinderedsettlingfunctiondataforreplicatealumsludgesamples.Asteriskedsamplesaretakenasrepresentativeinsubsequentcharts. ............................................................. 243Figure41:Eectofsolidphasedensity,S,onthecompressiveyieldstressofasludgewithtypicaldewateringproperties.Theenvelopedenedbythebrokenlinesillustratestherangeofbehavioursencounteredfordrinkingwatersludges(withS=2500kg/m3)................. 254Figure42:Eectofsolidphasedensity,S,onthehinderedsettlingfunctionofasludgewithtypicaldewateringproperties.Theenvelopedenedbythebrokenlinesillustratestherangeofbehavioursencounteredfordrinkingwatersludges(withS=2500kg/m3)................. 255Figure43:RawandsmoothedXRDscansfortheMacarthurWFPferricsludgegenerated20050323andheatedat80C. ........................................................................................................... 275Figure44:SEMimageofairdriedlaboratoryferricsludge(9daysold):oneEDSmeasurementaveragedoverapproximately0.01mm2(centredonlargesthorizontalface).Theconcentriccirclesformedupondrying. ............................................................................................. 277Figure45:SEMimageofgrainsofcalciteinaplantferricsludge(agedsample)................................. 280DRINKING WATER TREATMENT SLUDGE PRODUCTION AND DEWATERABILITY xxxi Figure46:Powderxraydiractogramsforairdriedagedlaboratoryalumsludges. ........................ 280Figure47:Powderxraydiractogramsforanairdriedplantalumsludge,originalandfreezethawconditioned.Inuenceofblankshowndotted.......................................................... 281Figure48:Xraypowderdiractogramsforaselectionoffreshandagedferricsludges.Theagedplantsampleisosetby+50unitsforclarity.Agesinmonths............................................ 283Figure49:Xraypowderdiractogramsforaselectionofferricsludgeswithandwithoutheating.Theplantsamplesareosetby+100unitsforclarity...................................................... 284Figure410:Xraypowderdiractogramsforaselectionofferricsludges.Thecurvesareprogressivelyosetby+50unitsforclarity. ..................................................................................... 284Figure411:Solidphasedensitiesforvariousdrinkingwatersludgesasafunctionof.Dataobtainedusingvolumetricasksshownwithdottederrorbars. .................................................. 292Figure412:Solidphasedensitiesforvariousdrinkingwatersludgesasafunctionofcoagulantdose.Dataobtainedusingvolumetricasksshownwithdottederrorbars. .............................. 293Figure51:Eectofcoagulantdoseonpy()forarangeofalumsludgesatpH6.00.2. ..................... 312Figure52:EectofcoagulantdoseonR()forarangeofalumsludgesatpH6.00.2....................... 313Figure53:Eectofcoagulantdoseonpy()forarangeofalumsludgesatpH8.50.1andpH4.90.1. .................................................................................................................................................... 315Figure54:EectofcoagulantdoseonR()forarangeofalumsludgesatpH8.50.1andpH4.90.1. .................................................................................................................................................... 316Figure55:EectofcoagulationpHonpy()forarangeofalumsludgesat80mg(Al)/Ldose. ......... 317Figure56:EectofcoagulationpHonR()forarangeofalumsludgesat80mg(Al)/Ldose. .......... 318Figure57:EectofcoagulationpHonpy()forarangeofalumsludgesat5mg(Al)/Ldose. ........... 319Figure58:EectofcoagulationpHonR()forarangeofalumsludgesat5mg(Al)/Ldose. ............ 320Figure59:Contourplotofestimatedgelpoint,g,(i.e.atpy0+)forlaboratorygeneratedalumsludgesasafunctionofcoagulantdoseandcoagulationpH. ............................................. 323Figure510:Contourplotofsolidosity,,atpy=50kPaforlaboratorygeneratedalumsludgesasafunctionofcoagulantdoseandcoagulationpH. ...................................................................... 325Figure511:Contourplotofsolidosity,,atR=51010Pa.s/m2forlaboratorygeneratedalumsludgesasafunctionofcoagulantdoseandcoagulationpH......................................................... 326Figure512:Contourplotofsolidosity,,atR=11014Pa.s/m2forlaboratorygeneratedalumsludgesasafunctionofcoagulantdoseandcoagulationpH......................................................... 327Figure513:Contourplotofhinderedsettlingfunction,R,[1013Pa.s/m2]atpy=50kPaforlaboratorygeneratedalumsludgesasafunctionofcoagulantdoseandcoagulationpH. ....... 328Figure514:VariationincompressiveyieldstresswithcoagulantdoseforvariousHappyValleyalumpilotplantsludges. ......................................................................................................... 332Figure515:VariationinhinderedsettlingfunctionwithcoagulantdoseforvariousHappyValleyalumpilotplantsludges. ......................................................................................................... 333Figure516:Compressiveyieldstressforlaboratorygeneratedandplantferricsludges.Theleftmostcurveisforthe80mg(Fe)/LpH5.6sample. ....................................................................... 337Figure517:Hinderedsettlingfunctionforlaboratorygeneratedandplantferricsludges. ............... 338D. I. VERRELLI xxxii Figure518:Comparisonofcompressiveyieldstressforalumandferricsludges.ThenumbersshowninthelegendarethecoagulantdoseandcoagulationpH. ................................................ 344Figure519:Comparisonofhinderedsettlingfunctionforalumandferricsludges.ThenumbersshowninthelegendarethecoagulantdoseandcoagulationpH................................. 345Figure520:ComparisonofKD/Lforalumandferricsludges.DataofFigure519. ......................... 346Figure521:Comparisonofsolidsdiusivityforalumandferricsludgesfullcurvesonloglogscale.ThenumbersshowninthelegendarethecoagulantdoseandcoagulationpH. ...... 347Figure522:Comparisonofsolidsdiusivityforalumandferricsludgesltrationdataonlyonloglinearscale.ThenumbersshowninthelegendarethecoagulantdoseandcoagulationpH. ..................................................................................................................................... 348Figure523:Compressiveyieldstressofamagnesiumsludge(nominalconditionsquotedseediscussionintext)comparedtotherangeoftypicallaboratoryalumsludgebehaviour. .............................................................................................................................................. 355Figure524:Hinderedsettlingfunctionofamagnesiumsludge(nominalconditionsquotedseediscussionintext)comparedtotherangeoftypicallaboratoryalumsludgebehaviour. .............................................................................................................................................. 356Figure61:Compressiveyieldstressforlaboratoryalumsludgesgeneratedfromspiked(dMIEX)andnonspiked(Lab.)rawwater. ...................................................................................... 368Figure62:Hinderedsettlingfunctionforlaboratoryalumsludgesgeneratedfromspiked(dMIEX)andnonspiked(Lab.)rawwater. ...................................................................................... 369Figure71:Compressiveyieldstressfortwopairsofsludgessubjectedtodierentshearintensitiesintheslowmixphase(givenasG).................................................................................. 389Figure72:Hinderedsettlingfunctionfortwopairsofsludgessubjectedtodierentshearintensitiesintheslowmixphase(givenasG).................................................................................. 390Figure73:Compressiveyieldstressfortwopairsofsludgeswhereocculantswereaddedtopromoteaggregation,comparedtocontrolswithnoocculant. ................................................. 395Figure74:Hinderedsettlingfunctionfortwopairsofsludgeswhereocculantswereaddedtopromoteaggregation,comparedtocontrolswithnoocculant. ................................................. 396Figure75:Schematicofthesludgeshearingandconditioningrig. ........................................................ 401Figure76:CSTvaluesforan80mg(Al)/LpH5.9laboratorysludgeat00.0026conditionedwithMagnaoc 338andZetag 7623atvariousdoses. ....................................................................... 409Figure77:CSTvaluesforan80mg(Al)/LpH8.9laboratorysludgeat00.0016conditionedwithZetag 7623atvariousdoses.SymbolsandlabelsasinFigure76. ....................................... 409Figure78:Hinderedsettlingfunctionestimatesbyvariousmethodsforan80mg(Al)/LpH5.9laboratorysludgeconditionedwith40mg/LZetag 7623,listedchronologically.preSSdenotesmaterialcollectedbeforetheconditioningoperationhadreachedsteadystate. .......... 412Figure79:Hinderedsettlingfunctionestimatesbyvariousmethodsforan80mg(Al)/LpH8.9laboratorysludgeconditionedwith40mg/LZetag 7623.Jackdenotesjackkniferesults(iterativeremovalofindividualrawdatapointsandreestimation). ........................................... 413Figure710:Sensitivityofparameterestimatestosubsetspecication. ................................................ 416Figure711:Errorestimates(95%condenceintervals)ontheequilibriumsolidsdiusivityandR2statisticforttingparameterE3...................................................................................................... 418DRINKING WATER TREATMENT SLUDGE PRODUCTION AND DEWATERABILITY xxxiii Figure712:ComparisonofD()datadeterminedfromsteppedpressurepermeabilityrunanalysis(bytwomethods)andfromtheextrapolationmethod(estimation)forzirconiaatpH7.0[reproducedfrom606].......................................................................................... 420Figure713:ComparisonofestimatesofRforan80mg(Al)/L,pH5.9laboratorysludge.................... 423Figure714:AsinFigure713,exceptafterconditioningthesludgewith90mg/LMagnaoc 338. ..... 423Figure715:CompressiveyieldstresscurvesforhighalumdoseWTPsludgesatmoderateandhighpHcoagulatedonly,sheared,andconditionedcases. ....................................................... 427Figure716:HinderedsettlingfunctioncurvesforhighalumdoseWTPsludgesatmoderateandhighpHcoagulatedonly,sheared,andconditionedcases.HighpHcurveshavebeenappropriatelyshifted(seetext),andarenotdirectlycomparablewithresultspresentedelsewhere. ............................................................................................................................ 428Figure717:Schematicofthemacroscopicstructuraldierencesbetweenconditionedandcoagulatedmaterialsasloadedintoaltrationcell......................................................................... 430Figure81:Compressiveyieldstressesforthreepairsoffreshandagedlaboratoryalumsludges.................................................................................................................................................... 439Figure82:Hinderedsettlingfunctionforonepairoffreshandagedlaboratoryalumsludges. ....... 440Figure83:CompressiveyieldstressesforapairoffreshandagedlaboratoryalumsludgespreparedfromrawwaterspikedwithdMIEX. ................................................................................ 441Figure84:Compressiveyieldstressesfortwosetsoffreshandagedferricsludges. .......................... 442Figure85:Hinderedsettlingfunctionfortwosetsoffreshandagedferricsludges. .......................... 443Figure86:Schematicoftheprogressiveexclusionofparticulatesbyamovingfreezefront.............. 458Figure87:Compressiveyieldstressofsludgessubjectedtofreezethawconditioning.Thethinnercurvesatleftillustratebehaviouroftheunconditionedsludges. .................................... 459Figure88:Hinderedsettlingfunctionofsludgessubjectedtofreezethawconditioning.Thethinnercurvesattopandleftillustratebehaviouroftheunconditionedsludges....................... 460Figure89:CompressiveyieldstressforalumpilotplantsludgesofvaryingcoagulantdosecomparedtoapilotplantsludgeofintermediatecoagulantdosebutcontainingsomealgandahighPACload(pHassumedtobecomparable). ......................................................... 465Figure810:HinderedsettlingfunctionforalumpilotplantsludgesofvaryingcoagulantdosecomparedtoapilotplantsludgeofintermediatecoagulantdosebutcontainingsomealgandahighPACload(pHassumedtobecomparable). ......................................................... 466Figure91:Gravitybatchsettlingofalumsludge(80mg(Al)/L,pH5.9)conditionedwithZetag 7623. ........................................................................................................................................................ 484Figure92:Gravitybatchsettlingofalumsludge(80mg(Al)/L,pH8.9)conditionedwithZetag 7623. ........................................................................................................................................................ 484Figure93:Gravitybatchsettlingofanalumsludgeincylindersofvaryingcapacityanddiameter(asindicatedinthelegend). ................................................................................................ 491Figure94:Comparisonofsettlingofplantalumsludgewithsilylatedglasswallsagainstsettlinginanunmodiedglasscylinder............................................................................................ 495Figure95:Meniscusofuntreatedsurface(left)andofsurfacetreatedwithCTMS(right). ................ 496D. I. VERRELLI xxxiv Figure96:Strandsofvegetationadheringtocylinderwallforlaboratoryalumsludge[Winnekerawwater20040511coagulatedwith1.5mg(Al)/LatpH6.0(20040819)](left),andplantalumsludge[WinnekeWTPsludge20050405(on20050617)](right). ......... 499Figure97:MacarthurWFPplantferricsludge20050921(on20070202).Imagesofsyneresedsludgeandbiomembraneundertensionbetweenliquidmeniscusandcrownofshrunkensludgebed. ........................................................................................................ 499Figure98:Centraldepression,vegetation,andmaterialrolledagainst(ordown)thewalls,insludgefromWinnekerawwater20040705withdMIEX,5mg(Al)/L,pH6.0(20050107).Largescalefeaturesoftheinterfaceareshownschematicallyatrightincrosssection. ............ 500Figure99:BatchsettlingofMacarthurWFPferricsludge20050323.Photograph(taken20050617)andschematiccrosssection.Atlongtimesextensivestraticationdeveloped:thelower(charcoalcoloured)layerunderwentsyneresis,andsupportsaplugofwellpackedwhitematerial,withuyrustcolouredocsontopsomeocsfromthetoplayerhavefallenpasttheplugintothegapcreatedbytheshrinkage.Severalcracksarealsoapparent. ........................................................................................................................................ 501Figure910:Continuationofsettlingafterasymptoteappearedtohavebeenreached.Thesamplewaslaboratoryferricsludgeat160mg(Fe)/LandpH5.1(seeTable54)...................... 505Figure911:Batchsettlingofplantferricsludge[MacarthurWFP,20050323(seeTable54)].Arrowsindicatetheendofaheightplateau................................................................................... 505Figure912(a):Batchsettlingofaferricsludge,80mg(Fe)/LandpH6.1,showingtendenciestowardlogarithmictypeprimarycreepatlongtimesintworegions. ......................................... 507Figure913:Endpointpredictionforalaboratoryalumsludgeat80mg(Al)/LandpH4.8(seeTable51(b)).ThecrosseslabelledPredictedh(exp.t)representthepredictionbasedonapplyingtheexponentialtoversevendatapointsuptothattime;hereR2representsthecoecientofdetermination. ...................................................................................... 509Figure914:CurvesttedtobatchsettlingdataforadMIEXalumsludgeat5mg(Al)/LandpH6.0(seeTable62).Onlythelineartovertherstsectionhasacleartheoreticalbasis. ....................................................................................................................................................... 510Figure915:Linearregressionondt/dV2forthreepressuresinasteppedpressurecompressibilityrun.Thedashedcurveisthe40pointpriormovingaverageofdt/dV2typicallyconsidered(defaultoutputofPress-o-maticsoftware);thepointsareobtainedfroma2pointcentralmovingaverage(thatis,localt/V2)andarebetterestimates,albeitnoisier........................................................................................................................................... 512Figure916:Standardlinearregressionsoftagainstln(E3V)forlongandshortsetsofdataoptimisingR2,andalternativetsoptimisingthetofV2anditsslopeagainstt. ..................... 513Figure917:LongtimetstoV2anddt/dV2overthelast141pointsusingequation2125bwithstandard(LW)andmodied(LW)parameterestimation,andusinganassumptionoflinearbehaviourindt/dV2(DIV). ...................................................................................................... 514Figure918:LongtimetstoV2anddt/dV2overthelast41pointsusingequation2125bwithstandard(LW)andmodied(LW)parameterestimation,andusinganassumptionoflinearbehaviourindt/dV2(DIV). ...................................................................................................... 515Figure919:Preliminaryindicationsofelasticcakereexpansioninbatchcentrifugation.Arrowsindicatedatapointsofinterest,wherehincreasedafterleavingthesampletostand. ...................................................................................................................................................... 522DRINKING WATER TREATMENT SLUDGE PRODUCTION AND DEWATERABILITY xxxv Figure920:CompressiveloadingandunloadingcurvesforaPACdosedalumWTPsludge;dataofKOS&ADRIAN[598].So