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 Drinking Water Treatment Sludge Production and Dewaterability David Ignatius Verrelli D. I. Verrelli Melbourne National Library of Australia Cataloguing-in-Publication entry Author:Verrelli, David Ignatius, 1977- Title:Drinking water treatment sludge production and dewaterability [electronic resource] /David Ignatius Verrelli. ISBN:9780980629729 (pdf.) Notes:Bibliography. Subjects:Drinking water--Purification. Water--Purification. Water treatment plant residuals. Water treatment plants--Waste disposal. Water treatment plant residuals--Management. Dewey Number:628.162 ISBN978-0-9806297-0-5(hard bound in 2 volumes) ISBN978-0-9806297-1-2(soft bound in 2 volumes) ISBN978-0-9806297-2-9(PDF, single le) D. I. Verrelli November 2008, March 2009, April 2009 Copying and printing are permitted for personal and approved uses. The authors moral rights are asserted. i SUMMARY Theprovisionofcleandr i nki ngwat er typicallyinvolvest r eat ment processesto removecontaminants.Theconventionalprocessinvolvescoagulationwithhydrolysing metalsalts,typicallyofaluminium(alum)ortrivalentiron(ferric).Alongwiththe productwaterthisalsoproducesawasteby-product,ors l udge.Thefactofincreasing sludgepr oduc t i onduetohigherlevelsoftreatmentandgreatervolumeofwater supply conicts with modern demands for environmental best practice, leading to higher nancialcosts.Afurtherissueisthesignicantquantityofwaterthatisheldupinthe sludge, and wasted. One means of dealing with these problems is to dewater the sludge further.This reduces the volume of waste to be disposed of.The consistency is also improved (e.g. for the purpose of landlling).Andasignicantamountofwatercanberecovered.Theeciency,and ecacy, of this process depends on thedewat er abi l i t y of the sludge. Infact,gooddewaterabilityisvitaltotheoperationofconventionaldrinkingwater treatmentplants(WTPs).Theusualprocessofseparatingtheparticulates,formedfroma blendofcontaminantsandcoagulatedprecipitate,reliesonclaricationandthickening, which are essentially settling operations of solidliquid separation. WTPoperatorsandresearchersdoattempttomeasuresludgedewaterability,but usuallyrelyonempiricalcharacterisationtechniquesthatdonottellthefullstoryandcan evenmislead.Understandingofthephysicalandchemicalnatureofthesludgeisalso surprisingly rudimentary, considering the long history of these processes. Thepresentworkbeginsbyreviewingthecurrentstateofknowledgeonrawwaterand sludgecomposition,withspecialfocusonsolidaluminiumandironphasesandonfractal aggregatestructure.Nextthetheoryofdewateringisexamined,withtheadopted phenomenological theory contrasted with empirical techniques and other theories. D. I. VERRELLI ii Thefoundationforsubsequentanalysesislaidbyexperimentalworkwhichestablishesthe solidphasedensityofWTPsludges.Additionally,alumsludgesarefoundtocontain pseudobhmite, while 2-line ferrihydrite and goethite are identied in ferric sludges. A key hypothesis is that dewaterability is partly determined by the treatment conditions.To investigate this, numerous WTP sludges were studied that had been generated under diverse conditions:someplantsampleswereobtained,andtheremainderweregeneratedinthe laboratory(resultswereconsistent).Dewaterabilitywascharacterisedforeachsludgein concentrationrangesrelevanttosettling,centrifugationandltrationusingmodels developedbyLANDMANandWHITEinteralia;itisexpressedintermsofbothequilibrium and kinetic parameters, py() and R() respectively. This work conrmed that dewaterability is signicantly inuenced by treatment conditions. The strongest correlations were observed when varying coagulation pH and coagulant dose.Athighdosesprecipitatedcoagulantcontrolsthesludgebehaviour,anddewaterabilityis poor.DewaterabilitydeterioratesaspHisincreasedforhigh-dosealumsludges;other sludgesarelesssensitivetopH.Thesendingscanbelinkedtothefastercoagulation dynamics prevailing at high coagulant and alkali dose. Alum and ferric sludges in general had comparable dewaterabilities, and the characteristics of a magnesium sludge were similar too. Small eects on dewaterability were observed in response to variations in raw water organic contentandshearing.Polymerocculationandconditioningappearedmainlytoaect dewaterabilityatlowsludgeconcentrations.Ageingdidnotproduceclearchangesin dewaterability. Dense, compact particles are known to dewater better than uy aggregates or ocs usually encounteredindrinkingwatertreatment.Thisexplainsthesuperiordewaterabilityofa sludgecontainingpowderedactivatedcarbon(PAC).Evengreaterimprovementswere observed following a cycle of sludge freezing and thawing for a wide range of WTP sludges. Furtheraspectsconsideredinthepresentworkincludedeviationsfromsimplifying assumptionsthatareusuallymade.Specically:investigationoflong-timedewatering behaviour, wall eects, non-isotropic stresses, and reversibility of dewatering (or elasticity). DRINKING WATER TREATMENT SLUDGE PRODUCTION AND DEWATERABILITY iii Severalotherresultsandconclusions,ofboththeoreticalandexperimentalnature,are presentedontopicsofsubsidiaryorperipheralinterestthatarenonethelessimportantfor establishing a reliable basis for research in this area. Thisworkhasproposedlinksbetweenindustrialdrinkingwatercoagulationconditions, sludgedewaterabilityfromsettlingtoltration,andthemicrostructureoftheaggregates makingupthatsludge.Thisinformationcanbeusedwhenconsideringtheoperationor designofaWTPinordertooptimisesludgedewaterability,withintheconstraintsof producing drinking water of acceptable quality. Keywor ds ageing;aggregates;aluminiumsulfate;centrifugation;coagulation;creep;delayed settling;dewatering;elasticity;ferricchloride;ltration;occulation;ocs;fractal dimension;freezethawconditioning;long-timebehaviour;magnesiumsulfate;natural organic matter;polymer;powdered activated carbon;reversibility;settling;sludge;shear;wall eects;water. I ndi cat i vet r ansl at i onsof t i t l e Trinkwasseraufbereitung:Erzeugung und Entwsserungsfhigkeit des Schlammes Trattamento delle acque potabili:La generazione e la facilit di disidratazione del fango Tratamiento de aguas potables:La generacin y la facilidad de deshidratacin de fangos Traitementdel'eaupotable:Laformationetlafacilitdedshydratationdesboues (schlamms) () Behandling af Drikkevand, Slam Produktion og Evne Til at Afvande [cf. Drikkevand Behandling, Slam Produktion og Afvanding] Pengolahan Air Minum Pembentukan Endapan, Produksi Endapan Lumpur, dan Kemudahan Pemisahan Air dari Lumpur v DECLARATION This is to certify that: 1.thethesiscomprisesonlymyoriginalworktowardsthePh.D.,exceptwhere indicated in the Preface & Acknowledgements; 2.due acknowledgement has been made in the text to all other material used;and3.thethesisisapproximately130000wordsinlength,exclusiveoftables,maps, bibliographies and appendices. David Ignatius Verrelli vii PREFACE ThisworkwasinitiatedaspartofaprojectcarriedoutasacollaborationbetweenThe University of Melbourne, United Utilities (U.K.), and Yorkshire Water (U.K.). I entered this course of study with the dual aims of furthering my own knowledge and skills, andarrivingatresearchoutcomesthathaverealapplication.Thetopicofdrinkingwater treatmentsludgedewateringdoesindeedhaveadirectrelevancetoindustry,andthus indirectly aects the community.I have learned a great deal in my research, and hope that my ndings will fall on receptive ears. IthastraditionallybeenthedutyofacademicsandPh.D.candidatestochallengeaccepted wisdom.Variouspressurescombinetodiscouragetheseenquiries.Toofrequentandtoo greatisthetemptationtotaketheexpedientpathofaccepting,withoutquestion,the establisheddoctrineoftheday.ExamplesincludeuseofA400nmtoestimatetruecolour,the derivation(s) of TERZAGHIs hydraulic diusion equation, omission of CORIOLIS forces, use of nominalSvalues,descriptionofalumandferricprecipitatesasAl(OH)3andFe(OH)3,the irreversibilityofdewatering,descriptionofdewaterabilitywithonlyD(),conationofDf withinternalaggregatestructure,andbeliefthatsmallerDfguaranteessmalleragg(all elucidated herein). Ihavebeenfortunatetohavehadtheimplicitsupportofmysupervisorstocorrectthese fundamental errors.I would particularly like to thank Peter Scales for his patience. ix ACKNOWLEDGEMENTS ThisworkwascarriedoutunderthesupervisionofProf.PeterJ.Scales&Dr.DavidR. Dixon.They have added considerable expertise and experience to the project. Thisworkwouldnothavebeenpossiblewithouttheassistanceofpostdoctoralresearch fellowsDr.ShaneP.Usher&Dr.RossG.deKretser.Itisraretondatechnicalproblem they are unable to resolve. I would also like to acknowledge the fellowship of the other members of the Scales research group,pastandpresent.Whileitisnotpossibletolistthemallindividually,itwouldbe remiss not to mention Rachael C. Wall, Rudolf Spehar, Hemadri K. Saha and Ainul A. b. A. Aziz. Numerous other members of the Department of Chemical and Biomolecular Engineering, the ParticulateFluidsProcessingCentre,theSchoolofEngineering,andtheuniversityasa wholehavesupportedthiswork,eitherdirectlyorindirectly.Thisincludesstudents, general sta, and academics.Particular mention should be made of:the workshop sta KevinSmeatonandteam;theanalyticalfacilityErnestH.Gutsa;theSEMimaging facility Roger C. A. Curtain;the administrative sta;and the library sta. AccesstoequipmentwasfacilitatedbyG.W.Stevens(spectrophotometer)andM. Ashokkumar(TOC).S.E.Kentishandhergroupgenerouslygaveuplaboratoryspaceto accommodate my work. DiscussionswithL.R.White,T.W.Healy,R.J.Eldridge,G.V.Franks,P.Liovic,P.S. Grassia,E.K.Hill,F.Grieser,W.A.Ducker,andB.Jeersonareappreciated,asare correspondencewithV.J.Blue,J.Bellwood,E.M.Furst,R.Simard&P.LEcuyer,R.M.L. Evans,J.-P.Jolivet,W.R.Knocke,andJ.H.Kwon.AssistancefromInaRitsnerwitha Russian text is also gratefully acknowledged.Thanks to James Tardio for helping to validate TOC results.I also recognise Peter Jarviss generosity in providing access to his collection of articles from the literature.Thanks to Nathan Matteson for typography tips. D. I. VERRELLI x UnitedUtilitiesandYorkshireWaterprovidedprojectsponsorship,withparticularsupport from Dr. Martin Tillotson and Dr. Peter Hillis. TheAustralianResearchCouncilandTheUniversityofMelbourneprovidedfundsfora postgraduate scholarship. Melbourne Water (C. Barber et alii), the Cooperative Research Centre for Water Quality and Treatment(G.Newcombeetalia),UnitedUtilitiesAustralia(L.Choyetalii),andUnited Water(D.Beckeretalii),andCibaSpecialtyChemicals(J.Bellwood)areacknowledgedfor assistance in obtaining samples. Researchdoesnotalwaysrunsmoothly,andIwanttomakeespecialacknowledgementof Alicia for her companionship. Even when research does run smoothly, it is good to be able to take a break now and again, and spend time with friends. The path I have taken through the education system has formed the foundation upon which thesestudieshavebeenbuilt,andItrustreectsfavourablyuponWaverleyMeadowsP.S., Wheelers Hill S.C., and Monash University (Clayton) aside from my current institution. Finally,myparents,Vince&Virginia,instilledinmeanappreciationforknowledgeand learning, and supported me continuously throughout my education, as well as at home, for which I am grateful.Along with my supervisors, they also assisted by proofreading the text. xi OVERVIEW OF CONTENTS 1. I NTRODUCTI ON . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 2. BACKGROUND. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57 3. EXPERI MENTALMETHODS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 157 4. SOLI DPHASEASSAYSANDDENSI TI ES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 253 5. EFFECTOFCOAGULANTTYPE, DOSE, ANDpH. . . . . . . . . . . . . . . . . . . . 301 6. EFFECTOFRAWWATERQUALI TY. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 359 7. EFFECTOFSHEARANDPOLYMERADDI TI ON . . . . . . . . . . . . . . . . . . . . . 375 8. EFFECTOFUNUSUALTREATMENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 433 9. UNUSUALMATERI ALBEHAVI OUR. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 469 10. OUTCOMES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 543 11. BI BLI OGRAPHY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 559 APPENDI CES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 619 REVI EW . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 621 SUPPORTI NGMATERI AL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 825 D. I. VERRELLI xii DRINKING WATER TREATMENT SLUDGE PRODUCTION AND DEWATERABILITY xiii DETAILED CONTENTS SUMMARY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iKeywords.......................................................................................................................... iii Indicative translations of title ........................................................................................ iii DECLARATI ON . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . v PREFACE. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vi iACKNOWLEDGEMENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . i x FI GURES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xxi x TABLES. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xxxi x NOMENCLATURE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xl i i iSymbols . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xl i i iLatin symbols............................................................................................................................ xliii Greek symbols.........................................................................................................................xlviii Cyrillic symbols ............................................................................................................................. l Mathematical operators and other symbols ............................................................................. li Superscripts................................................................................................................................... li Subscripts...................................................................................................................................... lii Abbrevi ati ons . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . l i i iTerminol ogy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . l v D. I. VERRELLI xiv 1. I NTRODUCTI ON . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 11Dri nkingwaterproducti onprocesses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 12Sl udgeproducti on. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 13Sl udgetransportation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 14Sl udgedewatering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 141Clarication and thickening.......................................................................................13 142Natural dewatering.....................................................................................................15 143Centrifugation..............................................................................................................18 144Filtration........................................................................................................................20 1441Filter presses.........................................................................................................20 1442Belt lter presses..................................................................................................22 1443Vacuum drum lters ...........................................................................................23 1444Other lters...........................................................................................................24 15Sl udgedisposal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 151Overview of disposal routes ......................................................................................26 152Discharge to a natural water body............................................................................28 153Discharge to sewer ......................................................................................................31 154Discharge to lagoons...................................................................................................34 155Waste landll ...............................................................................................................36 156Engineering ll.............................................................................................................40 157Land application, including agricultural uses.........................................................41 1571Regulatory issues.................................................................................................45 158Chemical reuse.............................................................................................................47 159Other benecial uses ...................................................................................................49 16Thenexusbetweensl udgegenerati on, sludgedewateri ng, and sl udgedi sposal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51 17Ai mofthiswork . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52 DRINKING WATER TREATMENT SLUDGE PRODUCTION AND DEWATERABILITY xv 2. BACKGROUND. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57 21Introductiontodewateri ng . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58 211Solidosity ......................................................................................................................59 212Dewatering regimes ....................................................................................................60 213The dewatering spectrum ........................................................................................62 214Driving forces and resistances to dewatering.......................................................64 215Packing..........................................................................................................................67 22Sl owparticl emoti on . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68 23Fl owthroughporousmedi a . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71 231DARCYs law.................................................................................................................71 232Extensions and alternatives to DARCYs law............................................................75 24Dewateringanal ysi s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76 241Empirical methods ......................................................................................................78 2411Compressibility....................................................................................................82 Isothermal compressibility..............................................................................................82 Extension to particulate systems....................................................................................82 Coecient of volume compressibility...........................................................................84 Reciprocal conned elastic modulus ...........................................................................85 Compressibility coecients............................................................................................86 2412Zone settling rate .................................................................................................86 2412(a)Denition of zone settling.............................................................................86 2412(b)Measurement ..................................................................................................87 2413Capillary suction time (CST) and derivatives .................................................88 2414Specic resistance to ltration (SRF).................................................................90 2414(a)Adjusted SRF ..................................................................................................91 2415Other ad hoc methods ..........................................................................................92 242Early dewatering theory.............................................................................................93 243Kinematical batch settling theory of KYNCH ...........................................................93 2431Shock thickness ....................................................................................................95 2432Polydisperse suspensions and instability ........................................................96 2433Inuence of BROWNian motion..........................................................................99 D. I. VERRELLI xvi 244Permeation theories of settling and ltration........................................................100 245Phenomenological dewatering theory of LANDMAN, WHITE et alia ...................104 2451Model parameters..............................................................................................105 2451(a)Compressive yield stress.............................................................................106 System anisotropy and osmosis ..................................................................................107 Empirical and model functional forms of py() ........................................................109 Creep eects at low stresses.........................................................................................109 Elastic behaviour ...........................................................................................................111 2451(b)Hindered settling parameters ..................................................................111 Empirical and model functional forms of R() .........................................................113 2451(c)Dynamic compressibility ............................................................................113 2451(d)Solids diusivity...........................................................................................116 2452General equations..............................................................................................117 2453Batch settling......................................................................................................119 2453(a)Early time ......................................................................................................119 2453(b)General equation ..........................................................................................121 2453(c)Practical solution..........................................................................................122 2453(d)Settling in real systems ................................................................................126 2453(e)Ideal settling..................................................................................................128 2453(f)Multiple-test theory .....................................................................................129 2453(g)Long-time behaviour ...................................................................................132 2454Batch centrifugation ..........................................................................................133 2454(a)Comprehensive analysis .............................................................................134 2454(b)Simplied one-dimensional analysis.........................................................140 2455Permeation..........................................................................................................143 2456Filtration..............................................................................................................144 246Other continuum models .........................................................................................151 247Fundamental mechanistic theory............................................................................151 2471Micromechanical dependence of yield stress on d0......................................152 248Stochastic analysis .....................................................................................................155 DRINKING WATER TREATMENT SLUDGE PRODUCTION AND DEWATERABILITY xvii 3. EXPERI MENTALMETHODS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 157 31Treatmentparameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 157 32Experi mental materi al s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 161 321Puried water.............................................................................................................161 322Raw water...................................................................................................................161 323Coagulants..................................................................................................................164 3231Magnesium.........................................................................................................164 324Alkali ...........................................................................................................................166 3241Hydrolysis ratio.................................................................................................166 325Polymers .....................................................................................................................168 326Plant and pilot plant sludges ...................................................................................168 3261Winneke ..............................................................................................................168 3262Macarthur ...........................................................................................................169 3263Happy Valley .....................................................................................................171 33Sl udgegeneration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 172 331Industrial practice......................................................................................................172 332Scaling by velocity gradient .....................................................................................173 3321Standard tank conguration..........................................................................174 333Jar test rig (optimal dose selection).........................................................................178 3331Mechanical construction and operation.........................................................178 3332Identifying the optimum..................................................................................180 334Tank.............................................................................................................................181 335Reproducibility ..........................................................................................................185 336pH................................................................................................................................185 34Treatmentcharacteri sati on. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 186 341Absorbance.................................................................................................................186 3411Procedure............................................................................................................187 3412Spectra.................................................................................................................188 3413Single wavelengths............................................................................................188 342True colour .................................................................................................................190 D. I. VERRELLI xviii 3421Spectrophotometric determination.................................................................191 3421(a)Estimation from single-wavelength absorbance......................................193 343Turbidity.....................................................................................................................194 3431Measurement......................................................................................................194 3432Experimental ......................................................................................................195 344Dissolved organic carbon (DOC) ............................................................................196 345Total solids and dissolved solids.............................................................................200 346Conductivity...............................................................................................................200 35Sl udgecharacterisati oncompressional rheology . . . . . . . . . . . . . . . . . . . . . . . . 202 351Batch settling..............................................................................................................202 3511Temporal data (single test)...............................................................................203 3511(a)Reproducibility.............................................................................................203 3512Equilibrium data (multiple test) ......................................................................205 3513Accuracy .............................................................................................................206 352Batch centrifugation..................................................................................................207 3521Pre-thickening....................................................................................................208 3522Accelerated settling...........................................................................................208 3522(a)Results............................................................................................................211 Reproducibility ..............................................................................................................220 3522(b)Implications...................................................................................................221 353Dead-end ltration....................................................................................................222 3531Stepped pressure analysis ................................................................................223 3531(a)Reproducibility.............................................................................................224 3532Permeation..........................................................................................................228 3533Improvements made to methodology............................................................230 3533(a)Rig design and operation............................................................................230 3533(b)Data processing and analysis .....................................................................233 3534Key interferences ...............................................................................................233 3534(a)Temperature..................................................................................................233 3534(b)Violation of one-dimensional dewatering assumption ..........................235 354Reproducibility ..........................................................................................................239 DRINKING WATER TREATMENT SLUDGE PRODUCTION AND DEWATERABILITY xix 36Sl udgecharacterisati onshearyiel dstress . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 243 361Conventional subaerial slump tests........................................................................245 362Proposed subaqueous slump test............................................................................246 37Model l ingofuni toperati ons . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 249 371Gravity settling and centrifugation.........................................................................249 372Filtration......................................................................................................................249 4. SOLI DPHASEASSAYSANDDENSI TI ES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 253 41Publ i sheddata . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 255 411Mass balance of sludge generation .........................................................................255 412Pure component densities ........................................................................................259 413WTP sludge densities................................................................................................263 4131Bulk densities .....................................................................................................263 4132Solid phase densities .........................................................................................264 42Experi mental determi nationofcomposi ti on . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 267 421Method........................................................................................................................268 4211Energy-dispersive spectrometry (EDS) ..........................................................268 4211(a)Samples..........................................................................................................268 4212X-ray diraction (XRD).....................................................................................269 4212(a)Theory............................................................................................................269 4212(b)Reference data...............................................................................................270 4212(c)Equipment .....................................................................................................272 4212(d)Samples..........................................................................................................272 422Results .........................................................................................................................275 4221Energy-dispersive spectrometry (EDS) ..........................................................275 4222X-ray diraction (XRD).....................................................................................280 4222(a)Aluminium....................................................................................................280 4222(b)Iron .................................................................................................................282 423Discussion...................................................................................................................285 424Conclusions ................................................................................................................286 D. I. VERRELLI xx 43Experi mental densitydeterminati on. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 287 431Method........................................................................................................................287 4311Equipment ..........................................................................................................289 432Results .........................................................................................................................290 4321Liquid phase.......................................................................................................290 4322Solid phase..........................................................................................................291 433Model curves..............................................................................................................295 434Discussion...................................................................................................................296 435Conclusions ................................................................................................................299 5. EFFECTOFCOAGULANTTYPE, DOSE, ANDpH. . . . . . . . . . . . . . . . . . . . 301 51Publ i shedobservations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 301 511Eect of dose ..............................................................................................................301 512Eect of pH and hydrolysis ratio............................................................................302 5121Aluminium.........................................................................................................303 5122Iron.......................................................................................................................305 5123Magnesium.........................................................................................................306 513Eect of coagulant .....................................................................................................306 52Materi alsandmethods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 308 53Al umsl udges: variati onofdose . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 311 531Results and discussion..............................................................................................311 5311Intermediate pH (6) ...........................................................................................311 5312High (8) and low (5) pH................................................................................314 532Conclusions ................................................................................................................316 54Al umsl udges: variati onofpH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 317 541Results and discussion..............................................................................................317 542Conclusions ................................................................................................................321 55Al umsl udges: combi neddosepHeffects. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 321 56Al umsl udges: compari sonwithpl antandpi l otpl antdata . . . . . . . . . . . 330 561Winneke WTP ............................................................................................................330 DRINKING WATER TREATMENT SLUDGE PRODUCTION AND DEWATERABILITY xxi 562Happy Valley pilot plant ..........................................................................................330 563Other plants................................................................................................................334 57Ferri csl udges: variati onofdoseandpH. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 335 571Experimental ..............................................................................................................335 572Results and discussion..............................................................................................337 573Conclusions ................................................................................................................340 58Ferri csl udges: comparisonwi thplantdata . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 341 581Macarthur WFP..........................................................................................................341 582Other plants................................................................................................................342 59Compari sonofal umandferri csl udges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 343 591Compressive yield stress and hindered settling function ...................................343 592DARCYs law permeability, KD.................................................................................345 593Solids diusivity........................................................................................................346 510Industri ali mpl i cations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 351 511Magnesi umsl udge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 352 5111Experimental ..............................................................................................................353 5112Results .........................................................................................................................354 5113Discussion...................................................................................................................356 5114Conclusions ................................................................................................................357 6. EFFECTOFRAWWATERQUALI TY. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 359 61Publ i shedobservations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 359 611NOM is benecial ......................................................................................................360 612NOM has no signicant eect .................................................................................360 613NOM is detrimental ..................................................................................................360 614NOM has a mixed eect ...........................................................................................362 62Experi mental . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 363 621Dialysed MIEX eluate (dMIEX)...........................................................................363 622Sludges ........................................................................................................................365 D. I. VERRELLI xxii 63Resul ts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 367 64Di scussi on. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 371 65Concl usi ons . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 373 7. EFFECTOFSHEARANDPOLYMERADDI TI ON . . . . . . . . . . . . . . . . . . . . . 375 71Previ ousinvesti gationsandexperi ence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 376 711Polymer addition.......................................................................................................376 712Shear ............................................................................................................................378 7121During formation...............................................................................................378 7122After formation, before settling.......................................................................383 7123After formation and settling ............................................................................385 72Shearduri ngcoagulati on . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 387 721Materials and methods .............................................................................................388 722Results .........................................................................................................................389 723Discussion and conclusions .....................................................................................391 73Fl occul ation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 392 731Materials and methods .............................................................................................392 732Results .........................................................................................................................394 733Discussion and conclusions .....................................................................................396 74Aftersettli ng: shearandpol ymerconditi oning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 397 741Methodology..............................................................................................................398 7411Materials .............................................................................................................398 7412Dose setting by capillary suction time (CST).................................................400 7413Shear and mixing rig.........................................................................................401 7414Characterisation.................................................................................................407 742Polymer dose selection .............................................................................................408 743Preliminary ndings .................................................................................................410 744Optimisation, error/sensitivity analysis, and calibration and validation..........414 7441Optimisation.......................................................................................................414 7442Error/sensitivity analysis..................................................................................415 DRINKING WATER TREATMENT SLUDGE PRODUCTION AND DEWATERABILITY xxiii 7442(a)Sub-set selection ...........................................................................................415 7442(b)Experimental and tting errors..................................................................417 7443Calibration and validation ...............................................................................420 7443(a)Approach.......................................................................................................420 7443(b)Moderate-pH sludges ..................................................................................421 7443(c)High-pH sludges ..........................................................................................424 745Principal results .........................................................................................................425 746Discussion...................................................................................................................429 747Conclusions ................................................................................................................431 8. EFFECTOFUNUSUALTREATMENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 433 81Agei ng . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 433 811Reported eects .........................................................................................................433 812Experimental methods..............................................................................................435 813Results .........................................................................................................................438 814Discussion...................................................................................................................443 815Conclusions ................................................................................................................445 82Freezethawcondi ti oni ng . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 445 821Background ................................................................................................................445 8211Mechanism..........................................................................................................446 8212Operational parameters....................................................................................449 8213Improvements to dewaterability.....................................................................454 8214Industrial application........................................................................................455 822Experimental methods..............................................................................................456 823Experimental results .................................................................................................457 824Discussion and conclusions .....................................................................................461 83Powderedacti vatedcarbon(PAC) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 462 831Reported eects .........................................................................................................462 832Equipment ..................................................................................................................463 833Materials .....................................................................................................................463 D. I. VERRELLI xxiv 834Experimental results .................................................................................................464 835Discussion and conclusions .....................................................................................466 9. UNUSUALMATERI ALBEHAVI OUR. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 469 91Inducti onti me . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 469 911Published observations and theories......................................................................469 9111Delayed settling .................................................................................................470 9111(a)Delay due to channelling ............................................................................471 9111(b)Delay due to densication ..........................................................................476 9111(c)Delay due to wall eects .............................................................................479 9112Deterministic chaos:self-organised criticality and periodicity..................480 912Practical relevance and analysis ..............................................................................482 913Experimental ndings...............................................................................................483 92Wal l effects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 486 921Cylinder diameter......................................................................................................486 9211Previous recommendations..............................................................................487 9211(a)Torpid matter................................................................................................488 9212Present ndings .................................................................................................490 9212(a)Settling...........................................................................................................490 9212(b)Filtration ........................................................................................................492 922Cylinder surface properties......................................................................................493 9221Experimental ......................................................................................................493 9222Results and discussion......................................................................................494 923Conclusions ................................................................................................................496 93Long-timedewateri ngbehaviour . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 497 931Ageing and biological activity during experiment...............................................498 9311Observed biological activity.............................................................................498 9312Development of large-scale morphology.......................................................499 9313Exposure to light................................................................................................501 9314Conclusions ........................................................................................................502 DRINKING WATER TREATMENT SLUDGE PRODUCTION AND DEWATERABILITY xxv 932Creep and long-time metastability..........................................................................503 9321Postulated behaviour ........................................................................................503 9322Settling.................................................................................................................504 9323Filtration..............................................................................................................511 9324Discussion...........................................................................................................515 9324(a)Bulk viscosity theory....................................................................................517 9324(b)Thermally-activated barrier hopping theory ...........................................518 9325Non-diusive processes ...................................................................................519 933Conclusions ................................................................................................................519 94Reversi bi li ty: El asticcakere-expansion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 521 941Literature reports.......................................................................................................523 942Elasticity theory .........................................................................................................529 943Methodology..............................................................................................................537 944Results .........................................................................................................................538 945Discussion and conclusions .....................................................................................541 10. OUTCOMES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 543 101Catal ogueofoutcomesandconcl usi ons . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 543 1011Theoretical ..................................................................................................................543 1012Experimental ..............................................................................................................546 102Industri ali mpl i cations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 552 103Furtherwork . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 553 1031Experimental ..............................................................................................................553 1032Theoretical development ..........................................................................................555 104Cl osingremarks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 557 11. BI BLI OGRAPHY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 559 D. I. VERRELLI xxvi APPENDI CES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 619 REVI EW . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 621 R1. CONDI TI ONSAFFECTI NGTHENATUREOFTHESLUDGE MATERI ALFORMED . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 627 R11Importantconsti tuentsofrawwaternaturalorgani cmatter (NOM) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 627 R12Coagul ation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 640 R13Fl occul ation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 704 R14Mi xi ng . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 715 R15Aggregatestructureandfractal di mensi on. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 735 R2. BEHAVI OUROFSLUDGE- LI KEMATTER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 791 R21Endogenoussynresi s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 791 R22Geomechani csandcreep . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 799 R23Macrorheol ogi calmodels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 814 DRINKING WATER TREATMENT SLUDGE PRODUCTION AND DEWATERABILITY xxvii SUPPORTI NGMATERI AL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 825 S1. EARLYDEWATERI NGTHEORY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 831 S2. GENERALPRI NCI PLESOFKI NEMATI CWAVES . . . . . . . . . . . . . . . . . . . . 834 S3. EXPERI MENTALOBSERVATI ONSOFLONG- TI ME SETTLI NG . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 836 S4. DOUBLE- EXPONENTI ALVERSI ONOFLONG- TI ME FI LTRATI ONASYMPTOTE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 840 S5. STOCHASTI CSETTLI NGANALYSI S . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 841 S6. J ARTESTI NGPRACTI CE. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 843 S7. LI GHTABSORBANCE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 848 S8. COLOURMEASUREMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 856 S9. EVALUATI ONANDSELECTI ONOFSYRI NGEFI LTERS . . . . . . . . . 867 S10. MULTI PLEBATCHSETTLI NGANALYSI S . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 874 S11. SLUMPTESTRESULTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 892 S12. CONTOURSENSI TI VI TYANALYSI S . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 895 S13. FI LTERPRESSMODELLI NG . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 898 D. I. VERRELLI xxviii S14. POLYMERCONDI TI ONERMI XI NGRECOMMENDATI ON OFWRc . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 908 S15. BOOTSTRAPANDJ ACKKNI FESTATI STI CS . . . . . . . . . . . . . . . . . . . . . . . . . . 913 S16. SI LANI SATI ON . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 925 S17. BULKVI SCOSI TY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 928 S18. BARRI ERHOPPI NGTHEORY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 941 S19. FI LTRATI ONRI GFRAMEEXPANSI ON. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 943 S20. ESTI MATI ONOFTHEBULKMODULUSOF COMPRESSI BI LI TY, BS, THROUGHCENTRI FUGATI ON. . . . . . . . . 945 S21. METALCOMPLEXATI ONBY FOREI GN ANI ONS . . . . . . . . . . . . . . . . . 947 S22. PSEUDOBHMI TESTRUCTUREANDCOMPOSI TI ON . . . . . . . . . . . 954 S23. OCCURRENCEOFI RON( I I ) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 956 S24. RELATI VESTABI LI TYOFHMATI TEANDGOETHI TE . . . . . . . . 957 S25. CORRELATI ONSOFdma x. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 960 S26. ESTI MATI ONOFGFORI NDUSTRI ALSCENARI OS. . . . . . . . . . . . . . . 964 The Review and Supporting Material appendices each begin with adet ai l ed listing of their contents. DRINKING WATER TREATMENT SLUDGE PRODUCTION AND DEWATERABILITY xxix FIGURES Figure 1-1:Distribution of raw water sources and treatments in England and Wales circa 1997, by water volume [315].............................................................................................................................. 2 Figure 1-2:Indicative owchart of conventional water treatment process with gravity settling, including sludge processing operations. ............................................................................................... 5 Figure 1-3:U.K. landll tax rates since inception [53, 70, 72, 315].............................................................. 38 Figure 2-1:Simplied schematic of hypothetical equilibrium particle packing resulting from sequential application of axial and lateral stresses. ......................................................................... 108 Figure 2-2:Typical ux plot [cf. 205], showing key features of the settling ux function, Sq (), and illustrating the range of solidosities for which R() can be analytically evaluated for a given initial solidosity of 0 or 0:the range is the same, as material loaded at 0 jumps directly to 0 [cf. 652].Not to scale.................................................................................................... 123 Figure 2-3:Schematic representation of typical batch settling behaviour with 0 < g. ........................ 128 Figure 2-4:Schematic representation of typical batch settling behaviour with 0 > g [495]. .............. 128 Figure 2-5:Schematic of centrifuge system, looking down on plane of rotation.Gravity is assumed to act in the z direction....................................................................................................... 135 Figure 2-6:Interface settling rates ofcent ri fuged samples.(The two alternatives given for each sludge type refer to the local form of h(t) assumed in numerically estimating the derivative.) ............................................................................................................................................. 138 Figure 3-1:Range of alum sludges characterised. ...................................................................................... 158 Figure 3-2:Range of ferric sludges characterised. ...................................................................................... 159 Figure 3-3:Location of alum and ferric sludge generation conditions with respect to the aluminium and iron(III) solubility curves.Plant Al includes the pilot plant sludges............ 160 Figure 3-4:Experimental hydrolysis ratios for alum coagulation, [OH]added / [Al].The solubility envelope is indicated by the dashed lines. ........................................................................................ 167 Figure 3-5:Schematic of HOLLAND & CHAPMANs [485] standard tank conguration. ...................... 176 Figure 3-6:Large (53.5L) mixing vessel based on standard tank conguration................................... 182 Figure 3-7:Large-scale coagulation equipment. ......................................................................................... 183 Figure 3-8:Transient pH proles for ve consecutive ferric treatments at 80mg(Fe)/L carried out on Winneke raw water collected 2004-09-15. ............................................................................. 186 Figure 3-9:Compressive yield stress curves computed from seven batch settling tests.Centrifugation and ltration data also shown.................................................................................. 204 Figure 3-10:Hindered settling function curves computed from seven batch settling tests.Filtration data also shown. .................................................................................................................. 204 Figure 3-11:Compressive yield stress determined rst without centrifugation data, and then with centrifugation data, for a laboratory and a plant alum sludge.............................................. 212 D. I. VERRELLI xxx Figure 3-12:Compressive yield stress determined rst without centrifugation data, and then with centrifugation data, for a laboratory and a plant ferric sludge. ............................................ 213 Figure 3-13:Hindered settling function computed with and without centrifugation data for a laboratory and a plant alum sludge. .................................................................................................. 215 Figure 3-14:Hindered settling function computed with and without centrifugation data.Revised ts using centrifugation data were obtained only by adjusting py() as in Figure 3-11. ......................................................................................................................................................... 216 Figure 3-15:Predicted centrifugation h(t) proles.The prediction for the py() and R() curves obtained without centrifugation data is for comparison only.The rst improved t was obtained using the adjusted py() curve from Figure 3-11, and this was optimised to yield the second improved prediction by iteratively adjusting R() to yield the curve shown in Figure 3-13. ........................................................................................................................................ 219 Figure 3-16:Predicted gravity settling h(t) proles.The rst prediction uses py() and R() curves obtained without centrifugation data.The second prediction was obtained using the adjusted py() curve from Figure 3-11.The nal prediction was obtained by iteratively adjusting R() (see Figure 3-13) to optimise the predicted centrifugation h(t) prole (see Figure 3-15)........................................................................................................................ 220 Figure 3-17:Schematic of laboratory ltration rig. ..................................................................................... 222 Figure 3-18:Duplicate compressive yield stress measurements from stepped-pressure ltration. .... 226 Figure 3-19:Hindered settling function estimates from duplicate stepped-pressure permeability runs, based onaverage of py() measurements. ............................................................................ 227 Figure 3-20:(a)The period from 500 to 1700 seconds shows the close control of sample pressure attainable using automatic control when the rate of dewatering is not too high. (b)the period from 340 to 370 seconds shows the level of control achievable using manual control when the rate of dewatering is high..................................................................... 229 Figure 3-21:Thermal cycling in ltration.160mg(Fe)/L sludge ltered on newer aluminium-framed rig. ............................................................................................................................................ 234 Figure 3-22:Schematic of cake unloaded from ltration rig showing crevice in top surface and non-straight side prole.These features were present in a minority of cases............................. 239 Figure 3-23:Compressive yield stress data for replicate alum sludge samples. .................................... 242 Figure 3-24:Hindered settling function data for replicate alum sludge samples.Asterisked samples are taken as representative in subsequent charts. ............................................................. 243 Figure 4-1:Eect of solid phase density, S, on the compressive yield stress of a sludge with typical dewatering properties.The envelope dened by the broken lines illustrates the range of behaviours encountered for drinking water sludges (with S = 2500kg/m3)................. 254 Figure 4-2:Eect of solid phase density, S, on the hindered settling function of a sludge with typical dewatering properties.The envelope dened by the broken lines illustrates the range of behaviours encountered for drinking water sludges (with S = 2500kg/m3)................. 255 Figure 4-3:Raw and smoothed XRD scans for the Macarthur WFP ferric sludge generated 2005-03-23 and heated at 80C. ........................................................................................................... 275 Figure 4-4:SEM image of air-dried laboratory ferric sludge (9 days old):one EDS measurement averaged over approximately 0.01mm2 (centred on largest horizontal face).The concentric circles formed upon drying. ............................................................................................. 277 Figure 4-5:SEM image of grains of calcite in a plant ferric sludge (aged sample)................................. 280 DRINKING WATER TREATMENT SLUDGE PRODUCTION AND DEWATERABILITY xxxi Figure 4-6:Powder x-ray diractograms for air-dried aged laboratory alum sludges. ........................ 280 Figure 4-7:Powder x-ray diractograms for an air-dried plant alum sludge, original and freezethaw conditioned.Inuence of blank shown dotted.......................................................... 281 Figure 4-8:X-ray powder diractograms for a selection of fresh and aged ferric sludges.The aged plant sample is oset by +50 units for clarity.Ages in months............................................ 283 Figure 4-9:X-ray powder diractograms for a selection of ferric sludges with and without heating.The plant samples are oset by +100 units for clarity...................................................... 284 Figure 4-10:X-ray powder diractograms for a selection of ferric sludges.The curves are progressively oset by +50 units for clarity. ..................................................................................... 284 Figure 4-11:Solid phase densities for various drinking water sludges as a function of .Data obtained using volumetric asks shown with dotted error bars. .................................................. 292 Figure 4-12:Solid phase densities for various drinking water sludges as a function of coagulant dose.Data obtained using volumetric asks shown with dotted error bars. .............................. 293 Figure 5-1:Eect of coagulant dose on py() for a range of alum sludges at pH 6.00.2. ..................... 312 Figure 5-2:Eect of coagulant dose on R() for a range of alum sludges at pH 6.00.2....................... 313 Figure 5-3:Eect of coagulant dose on py() for a range of alum sludges at pH 8.50.1 and pH 4.90.1. .................................................................................................................................................... 315 Figure 5-4:Eect of coagulant dose on R() for a range of alum sludges at pH 8.50.1 and pH 4.90.1. .................................................................................................................................................... 316 Figure 5-5:Eect of coagulation pH on py() for a range of alum sludges at 80mg(Al)/L dose. ......... 317 Figure 5-6:Eect of coagulation pH on R() for a range of alum sludges at 80mg(Al)/L dose. .......... 318 Figure 5-7:Eect of coagulation pH on py() for a range of alum sludges at 5mg(Al)/L dose. ........... 319 Figure 5-8:Eect of coagulation pH on R() for a range of alum sludges at 5mg(Al)/L dose. ............ 320 Figure 5-9:Contour plot of estimated gel point, g, (i.e. at py 0+) for laboratory-generated alum sludges as a function of coagulant dose and coagulation pH. ............................................. 323 Figure 5-10:Contour plot of solidosity, , at py = 50kPa for laboratory-generated alum sludges as a function of coagulant dose and coagulation pH. ...................................................................... 325 Figure 5-11:Contour plot of solidosity, , at R = 51010Pa.s/m2 for laboratory-generated alum sludges as a function of coagulant dose and coagulation pH......................................................... 326 Figure 5-12:Contour plot of solidosity, , at R = 11014Pa.s/m2 for laboratory-generated alum sludges as a function of coagulant dose and coagulation pH......................................................... 327 Figure 5-13:Contour plot of hindered settling function, R, [1013 Pa.s/m2] at py = 50kPa for laboratory-generated alum sludges as a function of coagulant dose and coagulation pH. ....... 328 Figure 5-14:Variation in compressive yield stress with coagulant dose for various Happy Valley alum pilot plant sludges. ......................................................................................................... 332 Figure 5-15:Variation in hindered settling function with coagulant dose for various Happy Valley alum pilot plant sludges. ......................................................................................................... 333 Figure 5-16:Compressive yield stress for laboratory-generated and plant ferric sludges.The leftmost curve is for the 80mg(Fe)/L pH 5.6 sample. ....................................................................... 337 Figure 5-17:Hindered settling function for laboratory-generated and plant ferric sludges. ............... 338 D. I. VERRELLI xxxii Figure 5-18:Comparison of compressive yield stress for alum and ferric sludges.The numbers shown in the legend are the coagulant dose and coagulation pH. ................................................ 344 Figure 5-19:Comparison of hindered settling function for alum and ferric sludges.The numbers shown in the legend are the coagulant dose and coagulation pH................................. 345 Figure 5-20:Comparison of KD / L for alum and ferric sludges.Data of Figure 5-19. ......................... 346 Figure 5-21:Comparison of solids diusivity for alum and ferric sludges full curves on loglog scale.The numbers shown in the legend are the coagulant dose and coagulation pH. ...... 347 Figure 5-22:Comparison of solids diusivity for alum and ferric sludges ltration data only on loglinear scale.The numbers shown in the legend are the coagulant dose and coagulation pH. ..................................................................................................................................... 348 Figure 5-23:Compressive yield stress of a magnesium sludge (nominal conditions quoted see discussion in text) compared to the range of typical laboratory alum sludge behaviour. .............................................................................................................................................. 355 Figure 5-24:Hindered settling function of a magnesium sludge (nominal conditions quoted see discussion in text) compared to the range of typical laboratory alum sludge behaviour. .............................................................................................................................................. 356 Figure 6-1:Compressive yield stress for laboratory alum sludges generated from spiked (dMIEX) and non-spiked (Lab.) raw water. ...................................................................................... 368 Figure 6-2:Hindered settling function for laboratory alum sludges generated from spiked (dMIEX) and non-spiked (Lab.) raw water. ...................................................................................... 369 Figure 7-1:Compressive yield stress for two pairs of sludges subjected to dierent shear intensities in the slow-mix phase (given as G).................................................................................. 389 Figure 7-2:Hindered settling function for two pairs of sludges subjected to dierent shear intensities in the slow-mix phase (given as G).................................................................................. 390 Figure 7-3:Compressive yield stress for two pairs of sludges where occulants were added to promote aggregation, compared to controls with no occulant. ................................................. 395 Figure 7-4:Hindered settling function for two pairs of sludges where occulants were added to promote aggregation, compared to controls with no occulant. ................................................. 396 Figure 7-5:Schematic of the sludge shearing and conditioning rig. ........................................................ 401 Figure 7-6:CST values for an 80mg(Al)/L pH 5.9 laboratory sludge at 0 0.0026 conditioned with Magnaoc 338 and Zetag 7623 at various doses. ....................................................................... 409 Figure 7-7:CST values for an 80mg(Al)/L pH 8.9 laboratory sludge at 0 0.0016 conditioned with Zetag 7623 at various doses.Symbols and labels as in Figure 7-6. ....................................... 409 Figure 7-8:Hindered settling function estimates by various methods for an 80mg(Al)/L pH 5.9 laboratory sludge conditioned with 40mg/L Zetag 7623, listed chronologically.preSS denotes material collected before the conditioning operation had reached steady state. .......... 412 Figure 7-9:Hindered settling function estimates by various methods for an 80mg(Al)/L pH 8.9 laboratory sludge conditioned with 40mg/L Zetag 7623.Jack denotes jackknife results (iterative removal of individual raw data points and re-estimation). ........................................... 413 Figure 7-10:Sensitivity of parameter estimates to sub-set specication. ................................................ 416 Figure 7-11:Error estimates (95% condence intervals) on the equilibrium solids diusivity and R2 statistic for tting parameter E3...................................................................................................... 418 DRINKING WATER TREATMENT SLUDGE PRODUCTION AND DEWATERABILITY xxxiii Figure 7-12:Comparison of D () data determined from stepped pressure permeability run analysis (by two methods) and from the extrapolation method ( estimation) for zirconia at pH 7.0 [reproduced from 606].......................................................................................... 420 Figure 7-13:Comparison of estimates of R for an 80mg(Al)/L, pH 5.9 laboratory sludge.................... 423 Figure 7-14:As in Figure 7-13, except after conditioning the sludge with 90mg/L Magnaoc 338. ..... 423 Figure 7-15:Compressive yield stress curves for high-alum-dose WTP sludges at moderate and high pH coagulated only, sheared, and conditioned cases. ....................................................... 427 Figure 7-16:Hindered settling function curves for high-alum-dose WTP sludges at moderate and high pH coagulated only, sheared, and conditioned cases.High-pH curves have been appropriately shifted (see text), and are not directly comparable with results presented elsewhere. ............................................................................................................................ 428 Figure 7-17:Schematic of the macroscopic structural dierences between conditioned and coagulated materials as loaded into a ltration cell......................................................................... 430 Figure 8-1:Compressive yield stresses for three pairs of fresh and aged laboratory alum sludges.................................................................................................................................................... 439 Figure 8-2:Hindered settling function for one pair of fresh and aged laboratory alum sludges. ....... 440 Figure 8-3:Compressive yield stresses for a pair of fresh and aged laboratory alum sludges prepared from raw water spiked with dMIEX. ................................................................................ 441 Figure 8-4:Compressive yield stresses for two sets of fresh and aged ferric sludges. .......................... 442 Figure 8-5:Hindered settling function for two sets of fresh and aged ferric sludges. .......................... 443 Figure 8-6:Schematic of the progressive exclusion of particulates by a moving freeze front.............. 458 Figure 8-7:Compressive yield stress of sludges subjected to freezethaw conditioning.The thinner curves at left illustrate behaviour of the unconditioned sludges. .................................... 459 Figure 8-8:Hindered settling function of sludges subjected to freezethaw conditioning.The thinner curves at top and left illustrate behaviour of the unconditioned sludges....................... 460 Figure 8-9:Compressive yield stress for alum pilot plant sludges of varying coagulant dose compared to a pilot plant sludge of intermediate coagulant dose but containing some alg and a high PAC load (pH assumed to be comparable). ......................................................... 465 Figure 8-10:Hindered settling function for alum pilot plant sludges of varying coagulant dose compared to a pilot plant sludge of intermediate coagulant dose but containing some alg and a high PAC load (pH assumed to be comparable). ......................................................... 466 Figure 9-1:Gravity batch settling of alum sludge (80mg(Al)/L, pH 5.9) conditioned with Zetag 7623. ........................................................................................................................................................ 484 Figure 9-2:Gravity batch settling of alum sludge (80mg(Al)/L, pH 8.9) conditioned with Zetag 7623. ........................................................................................................................................................ 484 Figure 9-3:Gravity batch settling of an alum sludge in cylinders of varying capacity and diameter (as indicated in the legend). ................................................................................................ 491 Figure 9-4:Comparison of settling of plant alum sludge with silylated glass walls against settling in an unmodied glass cylinder............................................................................................ 495 Figure 9-5:Meniscus of untreated surface (left) and of surface treated with CTMS (right). ................ 496 D. I. VERRELLI xxxiv Figure 9-6:Strands of vegetation adhering to cylinder wall for laboratory alum sludge [Winneke raw water 2004-05-11 coagulated with 1.5mg(Al)/L at pH 6.0 (2004-08-19)] (left), and plant alum sludge [Winneke WTP sludge 2005-04-05 (on 2005-06-17)] (right). ......... 499 Figure 9-7:Macarthur WFP plant ferric sludge 2005-09-21 (on 2007-02-02).Images of synresed sludge and biomembrane under tension between liquid meniscus and crown of shrunken sludge bed. ........................................................................................................ 499 Figure 9-8:Central depression, vegetation, and material rolled against (or down) the walls, in sludge from Winneke raw water 2004-07-05 with dMIEX, 5mg(Al)/L, pH 6.0 (2005-01-07).Large-scale features of the interface are shown schematically at right in cross-section. ............ 500 Figure 9-9:Batch settling of Macarthur WFP ferric sludge 2005-03-23.Photograph (taken 2005-06-17) and schematic cross-section.At long times extensive stratication developed:the lower (charcoal-coloured) layer underwent synresis, and supports a plug of well-packed white material, with uy rust-coloured ocs on top some ocs from the top layer have fallen past the plug into the gap created by the shrinkage.Several cracks are also apparent. ........................................................................................................................................ 501 Figure 9-10:Continuation of settling after asymptote appeared to have been reached.The sample was laboratory ferric sludge at 160mg(Fe)/L and pH 5.1 (s