Table Of ContentFLOCCULATION in
NATURAL and ENGINEERED
ENVIRONMENTAL SYSTEMS
Copyright 2005 by CRC Press
FLOCCULATION in
NATURAL and ENGINEERED
ENVIRONMENTAL SYSTEMS
Edited by
Ian G. Droppo • Gary G. Leppard
Steven N. Liss • Timothy G. Milligan
CRC PR ESS
Boca Raton London New York Washington, D.C.
Copyright 2005 by CRC Press
LibraryofCongressCataloging-in-PublicationData
Flocculationinnaturalandengineered
environmentalsystems/editedbyIanG.Droppo...[etal.].
p.cm.
Includesbibliographicalreferencesandindex.
ISBN1-56670-615-7(alk.paper)
1.Flocculation.2.Water—Purification. I.Droppo,IanG.
QD547.F5842004
628.1’622—dc22
2004056933
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Preface
Inthehistoryofenvironmentalscience,therehasprobablybeennogreaterstruggle
thantheattempttocontroltheimpactofthesedimentandsolidsgeneratedbynature
andhumaninfluence(includingindustrialprocessing)ontheterrestrialandaquatic
environmentandonsocioeconomicsingeneral.Untoldbillionsofdollarsarespent
eachyearondredgingtomaintainnavigationchannelsandharbors.Furthercostsare
addedbytheneedtotreatthesesedimentspriortodisposalbecauseofhighlevelsof
contaminationresultingfromanthropogenicimpactsontheenvironment.Significant
financialburdensariseasaresultoftheneedtoremovesolidsduringdrinkingwater
andwastewatertreatmentprocesses,anecessityforsustainabledevelopment,andthe
protectionofhumanandaquatichealth.Itisnowwellestablishedthatthemajority
of particles within natural (freshwater and saltwater) systems are present in a floc-
culatedform(i.e.,flocs),andthattheformationofflocsisessentialfortheeffective
performanceofengineeringprocessessuchasbiologicalwastewatertreatment.
Flocculationistheprocessofaggregatingsmallerparticlestogethertoformlar-
ger composite particles via various physical, chemical, and biological interactions.
These larger composite particles behave differently in terms of their physical (e.g.,
transport,settling),chemical(e.g.,contaminantuptakeandtransformation),andbio-
logical (e.g., community structure activities and metabolism) behavior relative to
theirconstituentindividualparticlesduetodifferencesinsize,shape,porosity,dens-
ity,andcompositionalcharacteristics.Giventhesesignificantbehavioraldifferences
betweenflocsperseandtheirindividualcomponentparts,flocculationinfluencesa
wide array of environmental phenomena related to sediment–water and sediment–
sedimentinteractions.Afewoftheseincludesedimentandcontaminanttransportin
variousaquaticecosystems,remediationofcontaminatedbedsediments,contamin-
atedbedsedimentstability,andhabitatdestructionresultingfromsedimentation(e.g.,
coralreef,salmonspawninggrounds,molluskhabitatdegradation).Theseconcerns,
coupled with the ubiquitous nature of flocs within natural and engineered systems
andthepotentialtoinfluenceflocpropertiestocontrolbettertheenvironmentaland
engineeringprocesses,havegeneratedanincreasedemphasisonflocresearch.
Thetraditionaldisciplineswithinsaltwater,freshwater,andengineeringresearch
have,however,remainedsomewhatmutuallyexclusiveintheirapproachtothestudy
of flocculation processes. This reality is facilitated by differences in external vari-
ables (e.g., environmental conditions), focus driven research, and discipline bias.
Regardlessofdifferencesindisciplineorapproach,thereisgreatscopeandutilityfor
thesharingofinformationbetweenscientistswhoworkinthesethreeflocenviron-
ments.Oftenmethodsusedinoneenvironmentcan,andshould,beusedinanother
to further our understanding of flocculation processes. While new developments in
v
Copyright 2005 by CRC Press
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vi Preface
genomics, nanotechnology, sampling, and modeling permit increasingly revealing
investigationsintoflocstructure, processes, andimpact, thereisstillafundamental
lackofknowledgerelatedtomanyaspectsoftheflocculationprocess.
Inlightoftheimportanceofflocculationwithinnaturalandengineeredsystems,
an international workshop was held on September 4 and 5, 2003, at the Canada
Centre for Inland Waters, Burlington, Ontario, Canada. The workshop brought
togetheracademicsandgovernmentscientistsfromaroundtheglobetoaddressthe
critical issue of sediment flocculation within freshwater, saltwater, and engineered
systems. During the workshop, participants representing these three environments
presented their research findings. Three focus areas were used to structure the
workshop: (a) modeling, (b) physicochemical, and (c) biological aspects of floc-
culation. Following individual presentations, the participants were divided up into
threeworkinggroupstoaddressassignedtopicsinthefocusareas.Eachfocusgroup
contained researchers from the freshwater, saltwater, and engineered systems to
ensure a cross-communication of ideas between environments and to facilitate an
understanding of the unifying principles of flocculation. Participants ranged from
geographers/geomorphologistswhoinvestigateflocculationasitrelatestosediment
source, transport, andfatewithinriversystems, sedimentologistsinterestedinfloc-
culation’s influence within depositional environments, biologists focusing on the
biopolymeric matrices and microbial consortia of flocs, oceanographers investig-
atingsedimenttransportanddeliverywithinestuariesandopenoceanenvironments,
and wastewater engineers/biologists interested in floc behavior within engineered
systems.
Thepeer-reviewed20chaptersthatcomprisethistextareorganizedbytheirenvir-
onmentofinvestigation.Thefinalchapteridentifiestheunifyingprinciplesthatwere
discussed within the workshop focus groups and from the preceding chapters. The
textprovidesauniqueperspectiveinthatitintegratesthenaturalsciencesandengin-
eeringfieldsastheyrelatetothecentralphenomenonofflocculation. Wehopethat
thearrayofinformationprovidedinthisbookwillbevaluabletoallthoseinterested
inflocculationissueswithinanyenvironment.
IanG.Droppo
GaryG.Leppard
StevenN.Liss
TimothyG.Milligan
Copyright 2005 by CRC Press
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Acknowledgments
The workshop and this resultant text would not have been made possible without
the generous support of our sponsors. We would like to thank the National Water
ResearchInstituteofEnvironmentCanada,theDepartmentofFisheriesandOceans,
theWastewaterTechnologyCentreofEnvironmentCanada,theBrockhouseInstitute
for Materials Research of McMaster University, Ryerson University, and the Inter-
national Association for Sediment Water Science for their support. The editors are
particularly grateful to the Natural Sciences and Engineering Research Council of
Canadafortheirfundingsupportrelatedtoresearchonflocculation.
Eachchapterhasbeenpeerreviewedbytwoorthreereviewersconsistentwith
the standards set for international scientific journals. We would like to thank these
reviewersfortheireffortsinthisregard.
Finally, wewouldliketothanktheNationalWaterResearchInstituteofEnvir-
onment Canada for hosting the workshop and John Lawrence, Michel Beland, and
JohnPrestonfortheirsupport.TheeffortsofElizabethWendel,MeenuPall,Dianne
Crabtree, Allana Manto, Quintin Rochfort, Christina Jaskot, and Brian Trapp of
EnvironmentCanadaleadingupto,during,andfollowingtheworkshoparegratefully
acknowledged.
Copyright 2005 by CRC Press
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About the Editors
Ian G. Droppo is a research scientist with the
National Water Research Institute of Environment
Canadaandisthecurrentelectedvicepresidentof
the International Association for Sediment Water
Science. Dr. Droppo holds adjunct professorships
atMcMasterUniversity, SchoolofGeographyand
Earth Sciences and at the State University of New
York,CollegeatBuffalo,DepartmentofGeography
and Planning. He holds undergraduate and M.Sc.
degreesinphysicalgeographyfromMcMasterUni-
versity, CanadaandaPh.D.inphysicalgeography
fromtheUniversityofExeter,UnitedKingdom.He
wasarecentrecipientofLeverhulmeInternational
Visiting Fellowship held at the University of Exeter in the United Kingdom. Dr.
Droppo’s research interests center around sediment dynamics within natural and
engineeredsystemswithparticularemphasisonflocculationprocesses.Hehasapplied
thisknowledgeinmultipleenvironmentsincludingurbanstormwatermanagement,
remediation of contaminated bed sediments, contaminated bed sediment stability,
andinthesource, fate, andeffectofsedimentsandassociatedcontaminantswithin
numerousaquaticenvironments.HisresearchissupportedbyawardsfromEnviron-
ment Canada, the Natural Sciences and Engineering Research Council of Canada,
andarangeofindustrialpartners.Hehasgivenmanyinvitedlecturesandseminarsat
internationalconferences,workshops,anduniversitiesandhastaughtmanysediment
chemistry monitoring courses in developing countries. Dr. Droppo has carried out
collaborativeresearchinCanada,UnitedStatesofAmerica,UnitedKingdom,Japan,
Mexico,AustraliaandThailandleadingtoover85peer-reviewedjournalpublications,
bookchapters,andtechnicalreports.
Copyright 2005 by CRC Press
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x AbouttheEditors
Gary G. Leppard is an environmental biochemist and microbiologist who studies
therolesofnaturalandengineeredaquaticaggregates(flocs,biofilms)inthetransport
andfateofcontaminants.Inconcertwiththeseactivities,hedevelopselectron-optical
meanstoanalyzethecolloidalstructureofnaturaldispersingagentsandtheflocsof
watertreatmenttanks.HejoinedthestaffoftheNationalWaterResearchInstituteof
EnvironmentCanadaatBurlington(ON)in1975,asaresearchscientist.Whilealso
holdingaprofessorshipatMcMasterUniversityandmembershipintheBrockhouse
InstituteforMaterialsResearch(Hamilton,ON),heisaFellowoftheInternational
UnionofPureandAppliedChemistryandaConsultingFellowoftheWorldInnov-
ationFoundation.Insequence,hewasaninvitedscientistattheUniversityofParis
(France),theUniversityofMilan(Italy),LavalUni-
versity(QuebecCity),theNationalResearchCoun-
cil of Canada (Ottawa), the University of Geneva
(Switzerland), the University of Vienna (Austria),
andtheRudjerBoskovicInstitute(Croatia).
Dr. Leppard received degrees in several fields
of biology and biological chemistry from the Uni-
versityofSaskatchewan(Saskatoon,SK)andfrom
Yale University (New Haven, CT, United States).
A Ph.D. in cell biology, with a specialization in
electron-opticalmethods,wasreceivedfromYalein
1968.Researchintereststhenextendedintobiogeo-
chemistry,wastewatertreatment,materialsscience,
andtheactivitiesofnaturalmicrobialconsortia.His
interdisciplinaryresearchhasledtoawardsfromthe
North Atlantic Treaty Organization, the Commis-
sion of the European Communities, and the RITE
innovativetechnologyorganizationinJapan,aswellasaroleontheeditorialboard
of the Encyclopedia of Analytical Science. Current scientific interests focus on the
control, by nanoscale phenomena, of macroscale effects in aquatic environments.
These interests are coupled to the development of technology for commercial use,
andincludeenvironmentalprojectsforsynchrotronlaboratories.
Copyright 2005 by CRC Press
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AbouttheEditors xi
StevenN.Lissisaprofessorofappliedmicrobio-
logy in the Department of Chemistry and Biology
at Ryerson University and is the Associate Dean
(Research, Development and Science Programs)
for the Faculty of Engineering and Applied Sci-
ence. Dr. Liss holds adjunct professorships at the
UniversityofTorontointheDepartmentsofChem-
ical Engineering and Applied Chemistry and Civil
Engineering.Dr.Lissholdsanundergraduatedegree
in microbiology and immunology from the Uni-
versity of Western Ontario (1980) and graduate
degrees in applied microbiology from the Univer-
sity of Saskatchewan (M.Sc, 1983; Ph.D., 1987).
Dr. Liss currently leads research projects on the
microbiologyofwastewatertreatment,waterwells,
and environmental biotechnology. His research is
supportedbyawardsfromtheNaturalSciencesandEngineeringResearchCouncilof
Canada,theNationalCentresofExcellence,OntarioCentresofExcellence,Environ-
mentCanada,CanadaFoundationforInnovation(CFI),andawiderangeofindustry
partners.Specificresearchactivitiesincludemicrobialflocarchitectureinengineered
and natural systems, microbial ecology, water quality, filamentous microorganisms
andbulkingproblems,biofoulingandmicrobial-basedtoolsforstudying,andmon-
itoringbiologicaltreatmentsystemsincludingDNAmicroarrays.Hislaboratoryhas
developedexpertiserelatedtothephysicochemicalpropertiesofmicrobialstructures,
theircompositionandstructure,andtheapplicationofadvancedopticalmicroscopy
instudyingmicrobialstructuresandphysiology. Hisresearchinwastewatermicro-
biology led to the Ryerson Distinguished Research Award in 1998. Dr. Liss has
supervised32graduatestudentsatthemastersandPh.D.levels.Heistheauthorand
co-authorofover100peer-reviewedjournalpublications,bookchapters,conference
presentations,andtechnicalreports.
Copyright 2005 by CRC Press
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xii AbouttheEditors
TimothyG.MilliganisaresearcherwiththeMar-
ineEnvironmentalSciencesDivision,Fisheriesand
OceansCanada. AsheadoftheParticleDynamics
LaboratoryattheBedfordInstituteofOceanography
he leads the group’s research into the behavior of
fineparticulatematerialinaquaticenvironments.He
received his B.Sc in geology and M.Sc in ocean-
ography from Dalhousie University and has been
involvedwithflocsforover30years.Whilehisini-
tialcontactwasinpulpmilleffluent,itwasthetime
spent with the late Dr. Kate Kranck, a pioneer in
flocculationstudiesinthemarineenvironment,that
gavehimhisloveofmud.Areasofinterestinclude
themechanismsgoverningthelossofsedimentfrom
riverplumes,theeffectofflocculationonthetrans-
port and fate of contaminants, and environmental
impactsofoffshoreoilandgasandaquaculture.Mr.
Milligan has led research projects in a wide range of geographical areas, from the
AmazontotheCanadianArctic.Whilehisworkconcentratesmainlyonthemarine
environment,thefateofterrestriallyderivedsedimentsandassociatedcontaminants
hasledhimintothestudyoffluvialtransportaswell.Mr.Milliganhasbeeninvolved
inmanyinternationalventures,severalofwhichhavereceivedfundingfromtheU.S.
OfficeofNavalResearch.Hisworkcombinesinsitutechniqueswithprocess-based
parameterizationofthesizedistributionsofthecomponentgrainsinsuspendedand
bottomsedimenttobetterunderstandthefateofmudinbothmarineandfreshwater
systems.Over80peer-reviewedprimarypublications,bookchapters,andtechnical
reportshavebeenproducedfromthiswork.
Copyright 2005 by CRC Press
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