risk-based management of mercury-impacted sites

RISK-BASEDMANAGEMENTOF MERCURY-IMPACTED SITES

NICOLENetwork for Industrially Contaminated Land in Europe

NETWORK FOR INDUSTRIALLY CONTAMINATED LAND IN EUROPE

1RISK-BASED MANAGEMENT OF MERCURY-IMPACTED SITES |

1 Introduction & Regulatory Context 3 2 MercuryPropertiesandInfluenceonFate&Transport 7 3 TechniquesandConsiderationsforRiskAssessment 13 4 SiteCharacterisationTechniques 17 5 SiteManagementTechniques 27 5.1 SoilExcavationandOff-siteDisposal 28 5.2SoilWashing 32 5.3Stabilisation/Solidification 35 5.4ThermalTreatment 43 5.5 OtherSoilTreatmentTechnologiesUnderDevelopment 52 5.6TechniquesToAddressGroundwater 53 5.7OtherGroundwaterTreatmentTechnologiesUnderDevelopment 56 6 BestPracticeRecommendations 59

TABLE OF CONTENTS

Prepared by:

OliverPhipps,JenniferBarrett,PaulHesketh,RichardBrown(ERM),

withvaluablecontributionsfromRogerJacquet(Solvay, Chair of the NICOLE Mercury

Working Group); Stany Pensaert (DEC – DEME Environmental Contractors, nv);

ChristianStiels(ECON Industries);RhysDavis,ChristineMardle,ChrisTaylor-Kingand

MartinHolmes(EnGlobe-Celtic);DimitriVlassopoulos(Anchor QEA, LLC);andmany

otherIndustrialMembersandServiceProviderswhopreferrednottobecited.

Design by:

OntwerpbureauDDC

www.ontwerpbureauddc.nl

+31(0)880120250

32 RISK-BASED MANAGEMENT OF MERCURY-IMPACTED SITES || RISK-BASED MANAGEMENT OF MERCURY-IMPACTED SITES

1 INTRODUCTION & REGULATORY CONTEXTThistechnicalbooklethasbeenpreparedonbehalfoftheNetworkforIndustriallyContaminatedLandinEurope(NICOLE)MercuryWorkingGrouptosharecasestudiesandbestpracticerelatedtothecharacterisationandmanagementofindustrialsitesimpactedbyMercury(Hg).NICOLEwasformedinFebruary1996forthestimulation,disseminationandexchangeofknowledgeregardingindustriallycontaminatedland.Its100membersfrom20Europeancountriescomefromindustry,tradeorganizations,serviceproviders,technologydevelopers,universities,independentresearchorganizationsandgovernmentalorganizations.MoreinformationaboutNICOLEcanbefoundat www.nicole.org.

OnlyforspecificindustriesisHgtypicallyfoundasaprincipalpollutant,oftenatrelatively-highconcentrations(e.g.100to1000mg/kg).Acommonexampleischlor-alkalisites,wherethemajorityoftheHgimpactsidentifiedinsurroundingsoilstypicallycomprisetheoriginalelementalformofHg.Mercuryhasalsobeenusedasakeyreactantintheproductionoforganiccompounds,suchasthesynthesisofvinylchlorideandacetaldehydefromacetylene.Atotherindustrialsites,Hgisoftenpresentasasecondarypollutant

atrelativelylowconcentrations(i.e.nottheprimaryriskdriver)1. AtypicalexampleisthepresenceofHgat1to10mg/kglevelsincoaltarcontaminatedsoilsatgasandcokingworks,originatingfromlowlevelsofHginthecoalthatisco-condensedwiththetarrysubstances.

RecentlegislativetextsandgovernmentpoliciesrestricttheindustrialuseofHginEuropeandcouldleadtotheclosureandredevelopmentofsomeindustrialoperationsusingHg.Mostoftheseaffectedfacilitieswillneedtobeinvestigatedandmanagementmeasuresmaysubsequentlyberequired.Thisconcernsnotonlychlor-alkaliplantsusingtheHgcellprocess,whicharethemajorityindustrialuserofHginEurope,butalsootherindustrialactivities,suchaswoodimpregnation,preciousmetalsrecovery,oilandgasproduction,andthemanufactureand/orrecyclingofbatteries,thermometers,andelectricalswitches.

TworecentpolicydevelopmentsincludetheUnitedNationsEnvironmentalProgramme(UNEP)GlobalMercuryConvention(Minamata Convention on Mercury)2 and an updated versionoftheEuropeanCommission’sBestAvailableTechniquesReferenceDocument(BREF)forthechlor-alkaliindustry3.


TheMinamataConventionisamultilateralenvironmentaltreatyagreedbyover140countrieson19thJanuary2013,addressingseveralHg-relatedindustrialactivities.Itwillrequiresignatorynationsto:

PhaseoutHginsomemanufacturingprocesses(acetaldehydeproductionby2018andchlor-alkaliproductionby2025)andrestrictitsuseelsewhere;

Reduceand,wherefeasible,eliminatetheuseofHginotherindustries,suchasartisanalgoldmining,andalsoreduceairemissionsfrompointsourcessuchascoalburning,cementproduction,smeltingofnon-ferrousmetalsandwasteincineration;and

Phase-outorreduceHguseinproducts,suchasbatteries,switches,lights,cosmetics,pesticidesandmeasuringdevicesanddentalamalgam.

ThehistoricuseofHgisalsoaddressedintheConvention,aseachsignatorynationmustdevelopappropriatestrategiestoidentifyandassesssitesimpactedbyHgorHgcompounds.Inaddition,theConventionaddressesthesupplyandtradeofHg,andsaferstorageand disposal.

TheEuropeanCommissionBREFsareoneofthemainreferencedocumentsusedbyEUMemberStateswhenissuingoperatingpermitsandestablishingemissionlimitsforindustrialinstallations.TheupdatedBREFforthechlor-alkaliindustry(CAKBREF)wasfinalisedinDecember2013,supplementingtheexistingEuropeanlegislativeframeworkrelatedtothechlor-alkaliindustry.TheCAKBREFstatesthatHgcellsarenolongerconsideredasBestAvailableTechnology(BAT).Assuch,HgcelltechnologycannolongerbeusedinEU-basedchlor-alkalisitespermittedundertheIndustrialEmissionsDirective(IED)beyond 11thDecember2017.TheBATconclusions(Chapter5ofCAKBREF)werepublishedintheEUOfficialJournalandarelegallybinding4.

TheupdatedEuropeanCommissionBREFsupplementsexistingEUDirectives(EC1102/2008and2011/97/EU),whichbantheexportofrecoveredmetallicHgoutsideoftheEU,restrictHgre-use,andspecifyrequirementsfortransportation,storageanddisposal.Somecountries(e.g.France)areconsideringthedevelopmentofcountry-specificguidelinesforthemanagementofHg-impactedsites.

ThoughHgexhibitsauniquecombinationofphysicalandchemicalpropertiescomparedtoothermetals,NICOLEbelievesthatthemanagementprinciplesforHg-impacted landshouldbethesameasforothercontaminants,applyingtheprinciplesof Risk-BasedLandManagement(RBLM)7,SustainableRemediation8andNet

1. INTRODUCTION & REGULATORY CONTEXT

EnvironmentalBenefitAnalysis9.ThechallengewithHg-impactedsitesistoacquiresufficientrepresentativedatatobuildarobustconceptualsitemodel(CSM)anddeterminethemostappropriatesitemanagementmeasures.Wehavepreparedthisbookletinlightoftherecentregulatorydevelopmentstosharecurrentinformation,

casestudiesandbestpracticerelatedtothecharacterisationandmanagementof Hg-impactedindustrialsites.Thefocusofthetechnicalbookletisonthemanagementof Hg-impactedsoilandgroundwater.Whilstsurfacewater,airemissions,sedimentsandothermediaarediscussedgenerically,theyarenottheprimaryfocus.


1. INTRODUCTION & REGULATORY CONTEXT

HgexhibitsuniquephysicalandchemicalpropertieswhicharecriticaltounderstandduringthecharacterisationandmanagementofHgimpactsatindustrialsites.TherearethreeprimaryformsofHg:

ElementalHg(Hg0),whichcanoccurinliquidand gaseous states;

InorganicHgspecies(e.g.mercurous[Hg+] chloride,mercuric[Hg2+]chloride,mercuricoxide,mercurysulphate);and

OrganicHgspecies(e.g.methyl-Hg).

TheseHgformscanbepresentintheenvironmentasmetallicpure-product(elemental),aqueousphase,gaseous phaseand/orboundtothesoilorother solids(e.g.concrete).

KnowingthespeciationoftheHgformspresent,aswellastheambientandanthropogenicgeochemistry,providesinsightintothelong-termbehaviourofHg,potentialmigrationpathways,receptors,risksandtheappropriatemanagementmeasurestocontrolsuchriskssustainably.

Understandingpastindustrialpractices,suchasthechemicalprocesses,typesofHgused,andhowrawmaterials,wastesandeffluentsweremanaged,isthefirststeptoidentifyingtheHgformsandspeciespotentiallyreleased,aswellasthelikelymigrationpathwaysintothesurroundingenvironment.Sitesamplingandinnovativelaboratoryanalysis,suchasselectivesequentialextractionandsolid-phaseHgpyrolysis/thermaldesorption,canthenbeusedtoquantifytheHgspeciespresentinsitesoilsandgroundwater.

MERCURY PROPERTIES AND INFLUENCE ON FATE & TRANSPORT

2


Elemental Hg (Hg0)ElementalHgisrelativelyinsolubleinwater,formingdensedropletsthatcanmigratelaterallyalongsub-surfaceutilitycorridors,drainagesystemsandsurroundingbackfill.ThehighdensityofelementalHgenhancestheriskofdownwardmigration,typicallyalongpreferentialpathways(e.g.coarsebackfillaroundpilings/foundations,rootlets,cracks/fissures)andduringdrillingorground-disturbingactivitiesthatcreatevoidsorground vibrations.

ThedensityandsurfacetensionofelementalHgarehigh,approximately13.5g/cm3 and 470dyn/cmat20°C,comparedto1g/cm3 and73dyn/cmforfreshwater.ElementalHgandsomeorganicHgspeciesarealsovolatile,whichcanleadtoairdispersionandpotentialvapourintrusion.

Oncereleasedtoground,elementalHgcanalsoremobilisethroughvolatilizationandsubsequentcondensationordeposition. Thistransportmechanismhasbeenshowntobemostprevalentinwarmerclimatesandareaswithlargetemperaturevariations.ThiscanleadtolateraldispersionofHgfromsourceareasandleadtotheaccumulationofelementalHgbeneathimpermeableslabsandbuildingsandontopofconcretefoundations.

Inorganic Hg (Hg+, Hg2+)Dependingontheambientgeochemistry,HgreleasedtotheenvironmentcantransformintootherHgfractionswithvaryingmobilityandtoxicity.ThekeyconditionsthatcontrolHgtransformationincludepH,temperature,

organicmatter,redoxpotential,cationexchangecapacity,grainsizeandporosity. ThemainprocessesthatcanincreaseHgmobilityareredoxchanges(e.g.oxidation,reduction)andmethylation:

Oxidation

Reduction

Methylation

Demethylation

Hg 0 Hg +1 Hg +2 CH3 Hg +

Oxidation can occur under acidic or basic conditions.Theprimaryoxidantistypicallyoxygen,withthefollowingreactionsoccurring:

Acidicconditions:

4Hg+O2+4H+ à2Hg2

2++2H2O

2Hg+O2+4H+ à2Hg++2H2O

2Hg2++ + O2+4H

+ à4Hg2++2H2O

BasicConditions:

2Hg+O2 à2HgO

ResidualchlorinecanalsooxidiseHg:

Acidicconditions:

2Hg+Cl2 àHg2Cl2Hg+Cl2 àHgCl2Hg2Cl2 + Cl2 à2HgCl2BasicConditions:

Hg+ + ClO- àHgO+Cl-

Hgcanformsaltswithvariablesolubilityincombinationwithvariousanions.Forexample,inthepresenceofexcesschloride(e.g.saltwater),Hgformsmoresolublechloridespecies.Onesuchspecies,mercuricchloride(HgCl2),hasasolubilityof6%at20°C.Mercurycanalsoformsolublecomplexeswithdissolvedorganicmatter.

2. MERCURY PROPERTIES AND INFLUENCE ON FATE & TRANSPORT

1.0

0,8

0,6

0,4

0,2

HSO SO

H2S

HS

-

0

-0,2

-0,4

-0,6

2 4 6 8 10 12 14

HgCl0

HgO

HCl

0

∑ Hg = 10-9 M∑ S = 10-4 MpCl = 3.8

Hg0

Hg0

pH

E h [Vo

lt]

Hg0H

2

HgS

Hg(OH)2

O2H

2 O0

HgS 22

2

H2 0

- 4

- 4

Organic Hg (Methyl-Hg).ThebiogeochemistryofHgiscomplex, havingbothaerobicandanaerobicpathways.Theprimaryprocessesaremethylationandde-methylation.Methylationisacomplexprocessthatgenerallyoccursunderanaerobicconditionsbutisdifficulttopredict. Currentresearchindicatesthatthe methylationprocessismediatedby sulphate-reducingbacteria11.

Methyl-Hgisofconcernduetoitsmobility,toxicityandbecauseitmaybebio-accumulatedinaquatic/marineanimalsinthefoodchain.BioaccumulationinaquaticspecieshasbeenshowntobeinfluencedbypHanddissolvedoxygen content12.Whilesulphate-reducingbacteriacanpromotemethylation,whichenhancesHgmobilityandtoxicity,sulphatereductioncanalsoformsulphide,which thenprecipitatesthehighly-insolublecinnabar (HgS).

De-methylationisaprocessthatgenerallyoccursunderoxidativeconditions.However,therearealsoreductivede-methylationpathways:

OxidativePathway:CH3HgàHg++ + CO2 ReductivePathway:CH3HgàHg0+CH4

VariousbacteriashowthecapacitytoreduceionicHgand/ormethyl-HgtoelementalHg13,andde-methylationhasbeendemonstratedwithanaerobicbacteria14.Infact,ithasbeenshownthatsomeofthesamebacteriathatareresponsibleformethylationarealsoimplicatedinde-methylation,dependingontheambientgeochemicalconditions.

Hg Pourbaix Diagram with Cl and S


A LARGE INDUSTRIAL COMPANY THAT HAD RECENTLY CEASED OPERATING THEIR MERCURY‑CELL CHLOR‑ALKALI PLANTS WAS DECIDING A STRATEGIC APPROACH FOR MANAGING THE PORTFOLIO.

Key learnings Understandingthepriorindustrialprocesses,includingmanagementofrawmaterials,wasteandeffluentsiscriticalforanticipatingHgdistributionandspeciation:

CellroomsàrelativelylowsolubilitybutvolatileelementalHg

BrineandHg-Naamalgamtreatmentàmoresolubleionicforms(e.g.HgCl2,Hg(OH)2)

Hgplumesingroundwateraretypicallyrelativelyshort,withmoderateconcen-trations(typically10sofμg/l),althoughlocalgeochemistrycanaffectthis.Migrationtodepthcanbeanissue,particularlywheninassociationwithdensebrinesolutions.

Effluentstreamsandairdispersioncanleadtosecondaryimpactsandoff-site migration.

Directmeasurement(e.g.surfacewater,sediments,air,fish,arablecrops,egetables)isthemosteffectivewaytoconvincestakeholdersoftrueimpactsandpotentialrisklevels.

CASE STUDY 1: CHLOR-ALKALI PLANTS

Identification of Hg SpeciesTheHgpresentinsoilorsedimentcanbefractionatedaccordingtoitschemicalreactivity,mobilityandpotentialbioavailabilityusinganalyticaltechniquessuchasSelectiveSequentialExtraction(SSE),performedbysomecommerciallabs(e.g.BrooksAppliedLabs15).SelectiveSequentialExtractionusesavarietyofextractantsrangingfromwatertoaqua regia(HCl/HNO3)todifferentiatetheHgformspresent,fromwater-solublecompoundstohighlyinsolublecompoundssuchascinnabar.ThisanalyticalmethodologyallowsaquantitativeassessmentofthedifferentHgspecies,includingpotentiallybioavailablespeciesandtheproportionofHgthatissemi-mobileornon-mobile.

Fraction Description Typical Compounds

Extractant

F1 watersoluble

HgCl2 deionizedwater

F2 weakacidsoluble

HgOHgSO4

pH2HCl/HOAc

F3 organo complexed

Hg-humicsHg2Cl2CH3Hg

1MKOH

F4 strongly complexed

mineralLatticeHg2Cl2Hg0

12MHNO3

F5 mineralbound

HgSm-HgSHgSeHgAu

aquaregia

Source: Brooks Applied Labs (www.brooksrand.com)

Aswithmostinorganiccompounds,metalswilltypicallyseekastablegeochemicalendpointwhenreleasedintotheenvironment.Inanaerobicenvironment,SSEfractionsF1,F2andF3typicallydominate.Conversely,inareducingenvironment,theF3,F4andF5fractionsdominateinmostcases.TheF1,F2andF3fractionsaremoremobileandthereforetypicallydrivetheneedforremediation.TheSSEfractionsF4andF5arerelativelyimmobile.

Other ConsiderationsThefateandtransportofHgintheenvironmentisalsoaffectedbysorptionontosoil,sedimentandothermaterials(e.g.concrete).Aswithmanyothercontaminants,Hgsorptionisstronglydependentupontheorganic content12ofthesoilorsediment.Inwater,inorganicHgandmethyl-Hgcanbindstronglytoorganicmatter.TheboundHgcanthenbetransportedasparticulatesorcolloidsinsurfacewaterorgroundwater.ThetransformationandmobilizationofHgfromthesoilorsedimentparticlestowhichitisadsorbedmaythenoccurbychemicalorbiologicalreductiontoelementalHgorbymicrobialconversiontomethyl-Hg.

Toillustratethis,arecentUSstudyshowedthetransportanddistributionofinorganicHginparticulateformfromminewastestonearbyreservoirsediment,anditssubsequentconversionintomethyl-Hgwithinthereservoir16.Highermethylationactivitywasseeninsedimentssubjectedtowet/dryconditionsresultingfromseasonalwaterlevel fluctuations.


CHLORINE AND CAUSTIC PRODUCTION FOR > 30 YEARS USING HG CELL TECHNOLOGY. PRIMARY RECEPTOR IS ADJACENT WATERWAY. SEDIMENTS WERE PREVIOUSLY DREDGED, BUT THEN RE‑CONTAMINATED BY SITE RUNOFF.

Key learnings Tropicalclimate,stronglyaerobicsubsurfaceconditions.

Selectivesequentialextractionanalysis(SSE)onresidualHgàprimarilyionic:

34%water-solubleFraction1 (HgCl2,HgSO4)

36%acid-solubleFraction2(HgO) 0.4%strongly-complexedFraction4(Hg0) Remaining29%Fraction3/Fraction5

(majoritylikelyorgano-complexed) Nomethyl-Hg

Proposedrisk-basedremediationàDredgehotspots,consolidateandstabiliseon-site.

CASE STUDY 2: CHLOR-ALKALI PLANT, TROPICS

Source: ERM

TheSNOWMANNetwork17recentlyundertookacomprehensiveEurope-widereviewofcurrentapproachesfortheassessmentofriskatHg-impactedsitesandprovidedbestpracticesuggestionsaspartoftheIMaHgProject (Enhanced Knowledge in Hg Fate and Transport for Improved Management of Hg Soil Contamination)18.Basedontheirreview,theprimaryhumanhealthexposurepathwaysforHg-impactedsitesinclude:

Inhalationofindoorair; Soil ingestion; and Ingestionofvegetablesorfishfromimpactedsites.

ThroughconsultationwithEuropeancontaminatedlandexperts,IMaHgfoundthattherisksassociatedwithHgexposurearegenerallyassessedsimilarlyindifferentcountries,butthespecificapproachesusedcandiffer.SomeEuropeancountries(e.g.England&Wales,Belgium[Flanders],theNetherlandsandSweden)havedevelopedandusetheirowngenericmodelsasabasisforestablishingsoilguidelinevalues,withthesamemodelsoftenmadeavailableandused

forsite-specificassessments(byincorporatingsite-specificdata).However,othercountries,suchasSpain,haveselectedandutiliseavarietyofgenericexposuremodelsanddatadevelopedelsewhere.

TheSNOWMANNetworkrecommendsassessingtheHgspeciespresentandtheirassociated bioavailability in order to support arobustsite-specifichumanhealthriskassessmentandtoidentifyefficientandeffectiverisk-basedremediationoptions.NICOLEsupportsthisrecommendation,sothatsite-specific,risk-based,sustainableandcost-effectivemanagementmeasuresareidentifiedandimplemented.

TECHNIQUES AND CONSIDERATIONS FOR RISK ASSESSMENT

3


Targeted risk mitigation e.g. ground water remediation, vapour barriers, vacuum extraction, institutional controls

Targeted risk mitigation (institutional controls may be required)

Targeted risk mitigation (institutional controls may be required)

COMMENT

§ The same as TIER 1, but less conservatism

§ If criteria for individual forms of Hg is exceeded. potentially important pathways and Hg-forms can be identified

§ If only generic SSV for total Hg exists, then there is a potential need for developing SSV for inorganic, organic and metallic mercury

§ Conservative clean-up (levels and action)

Potential risksScreening against generic criteria (Soil Screening Values, SSVs)

TIER 1

INPUTS ASSESSMENT OUTPUT

TIER 2

TIER 3 – Ingestion of soil

TIER 3 – Inhalation of vapour

TIER 3 – Intake of vegetables

§ Development of site specific criteria

§ Screening against specific criteria§ Identification of dominating

pathways

In-depth analysis of pathways and effects e.g:

§ Statisitcal analysis of site data§ In silico modeling

In-depth analysis of pathways and effects e.g:

§ Statisitcal analysis of site data§ Geochemical modeling§ Fate & transport modeling

§ Detailed conceptualisation of migration pathways

§ Measurement of soil gas, sub-slab gas or indoor air in combination with modeling

§ Comparison with target soil gas values

Potential risks

Estimated risk from soil ingestion

Estimated risk from intake of vegetables

Estimated risk from inhalation of indoor air and required risk reduction

§ Choice of land use§ Soilconcentration for inorganic,

organic & metallic Hg, or§ Total Hg concentration

Site specific data to generic model e.g:§ Exposure time for relevant pathways§ Soil and transport properties for

important pathways (e.g. porosity, permeability, density, organic content)

Site specific data to site specific model e.g:

§ Water-soluble and exchangeable Hg fraction

§ In vitro measurements of bioavailibility

§ In vivo measurements of bioavailibility

Direct measurements

Site specific data to site specific model e.g:

§ Concentration in soil gas§ Geochemical data§ Climate dataDirect measurements e.g.:§ Concentration in soil gas. sub-slab gas

or indoor air

Effect measurements e.g:§ Concentration in vegetation

DuetothevariableandcomplexpropertiesofthedifferentHgspecies,NICOLErecommendsthatexposurepathwaysandtheHgfractionsbeassessedindividuallyandnotlumpedtogethertoconsideronlytotalHg.ConsiderationofjusttotalHgcanresultintheover-orunder-estimationofrisklevels(morecommonlyover-estimation).Asabestpractice,itshouldbeclearfromtheriskassessmentwhichpathway(s)couldposeanunacceptable

riskandtowhatextentriskreductionisneededtoprotecthumanhealth.

TheSNOWMANNetwork’sfindingssupportNICOLE’srecommendationtouseacombinationofdirectfieldmeasurementsandgeochemicalmodellingtoefficientlycharacterisethedifferentHgformsandspeciespresentandassessthepotentialrisksassociatedwithaspecificsite.

3. TECHNIQUES AND CONSIDERATIONS FOR RISK ASSESSMENT

Fig1. Three Common Exposure Pathways for Hg (IMaHg Project), This chart and full IMaHg report can be found at www.snowmannetwork.com

WithintheIMaHgproject,afirstversionofanewgeochemicalmodel,HP119wasdevelopedtosupportHgriskassessmentsbymodellingthepartitioningofHgbetweensoil,porewater,poregasandelementalphases.Thismodelcurrentlyrequiresvalidationofthehypothesesbyexperimentalwork.Inparticular,toexperimentallystudythebehaviourofliquidHginporousmedia,withvariablefactorssuchasmoisturecontent,organicmatterandgrainsizedistribution.


Asforanyimpactedsite,theselectionofappropriateinvestigationtechniquesforHg-impactedsiteswilldependuponthesitesetting,geologicalcontextandthespecificobjectivesandrationaleforinvestigation.However,theuniquephysicochemicalpropertiesofHgoftenpresentadditionaltechnicalchallengesandhealthandsafetyconstraintsforsitecharacterisation.

Planning for Site CharacterisationPriortomobilisingintothefield,availableinformationrelatedtopastindustrialactivities,wastemanagementpractices,potentialHgsources,backgroundconcentrations,thedesiredfuturelanduse,potentialreceptors,andthesitegeological,hydrogeologicalandgeochemicalsettingshouldbecompiledandevaluatedtotheextentpossible.Asdescribedabove,understandingthepotentialspeciationoftheHgformspresentcanalsoprovidekeyinsightintotheHgfateandtransporttohelpfocustheinvestigationandidentifypossiblehealthandsafetyrisksduringsiteworks.Siteplansandotherinformationrelatedtositeinfrastructure,suchasthelocationsofsubsurfacepilings/foundationsanddrains,arealsoimportantforidentifyingpotentialpreferentialmigrationpathways.Thisinformationshouldbeusedtodevelopan

initialCSMthatoutlinespotentialsource-pathway-receptorlinkagesinordertofocussubsequentsiteinvestigation.

3-D Virtual site model showing mercury plume. Source: ERM

ThelateralextentofpotentialHgcontaminationinsoils,sedimentandsurfacewateristypicallyafunctionofthedurationandquantityofelementalHglosttotheenvironmentandthedirectionandstrengthoftheprevailingwinds.Therefore,meteorologicalfactorsthatcaninfluenceHgfateandtransport(aswellasmeasurementsofHgintheenvironment)shouldberecordedthroughoutthesitecharacterisationprogrammetosupportdatainterpretation,includingatmosphericpressure,wind speed/direction,temperature,humidityandrecentrainfall.

SITE CHARACTERI SATION TECHNIQUES4


The “Nugget Effect”ElementalHgcontaminationisoftensporadicallydistributedwithinsoilsandbuildingstructuresassmallbeads.Evenwhensitesoilconditionsarefairlyhomogenous,closeinspectionofthesoilfabricfrequentlyshowsHgbeadsdistributedunevenlywithinsmallvoids,fissuresandcrackscreatedbyrootlets(orotherobjects)andsurroundinggravelandcobbles.

lementalHgcancollectinfeaturessuchassubsurfacedrains,andthefoundations,walls,floorsandmetallicstructuressurroundingindustrialprocessescanincorporateHgthroughadsorption.Asaresult,theselectedsiteinvestigationtechniquesshouldbetailoredtoaccountfornon-uniformcontaminantdistribution(so-called“nuggeteffect”).

Ground Penetration TechniquesWhenconductingintrusivesamplingprogrammesatsuspectedHgsites,itisimportanttoconsiderthatthevibrationsfromtypicalinvestigationanddrillingmethodscanfurthermobiliseelementalHgintodeepersoilhorizons.Therefore,theuseoftechniques

withhighvibrationsshouldbeminimisedinareassuspectedofsignificantelementalHgcontamination.Aswithallimpactedsites,rigorousdecontaminationproceduresshouldbeemployedbetweensamplinglocationsandattheendoftheinvestigationprogramme.

Testpitsandexcavatortrenchescanbeeffectiveforthevisualcharacterisationandassessmentofshallowsoilstrata(e.g.forHgdroplets)andtofacilitatethecollectionofshallowsoilsamples.However,slowadvancementandcleardecision-makingisrequiredtoavoidpenetrationoflowpermeabilitylayersandincreasedriskofverticalmigration.AcombinationofvisualinspectionforHgdropletsandthescanningofsamples/soilcoreswithahand-heldvapourmonitorisrecommendedduringallintrusiveinvestigationactivities.Furtherinformationregardingin-situandex-situcharacterisationtechniquesaredescribedbelow.

Followinginvestigation,anyenvironmentalboreholesmustbeproperlybackfilledwithexpandablegrout(e.g.bentonite)toavoidcreatingpreferentialpathways,

4. SITE CHARACTERI SATION TECHNIQUES

Source: ERM

Source: ERM

andallinvestigationsshouldconsidertheimportanceofmaintainingtheintegrityoflowpermeability layers.

In-situ Site Characterisation TechniquesDuetoitsvolatility,elementalHgwillpartitionintothevapour-phaseandcanthusbedetectedinairandsoil-gas.Assuch,variouspassiveandactivesoil-gassamplingtechniquescanbeusedtorapidlyandcost-effectivelyobtainlargenumbersoffieldmeasurementsacrossasite,inordertoevaluatethedistributionofelementalHgandtoidentifypotentialhot-spotsorareasforfurtherinvestigation.Incomparisontoactivesoil-gassampling,passivesamplingtechniquesaretypicallywell-suitedforuseinshallowsoilwithlow-permeabilityorhighmoisture-contentorwhereaccessformoreintrusiveinvestigationtechniquesislimited.

PassivesoilgassamplingmodulesarecurrentlyofferedbysuppliersincludingBeaconEnvironmentalandAmplifiedGeochemicalImaging,LLC.However,AmplifiedGeochemicalImagingLLCdoesnotcurrentlyofferanalysisofHg.Thesorbent-basedmodulesaretypicallyinstalledinagridpatternwithintheshallowsoilhorizonandleftforaspecifiedperiodoftime(typically30to60days).Themodulesarethenretrievedandreturnedtothesupplierorlaboratoryforanalysis.Althoughresultingdatacannotbedirectlycomparedwithregulatorystandardsorexposurethresholds,passivesoilgassamplingprogrammeshavebeeneffectiveinidentifyingpotentialHghot-spots20.

ActivesoilgassamplingforelementalHgcanbeconductedusingdirect-pushdrillingtechnologiesandportableHgvapouranalysers(forreal-timedata)orsorbenttubes(forsubsequentlaboratoryanalysis).Speciallydesignedsoilgasprobes(suchastheGeoprobe®PostRunTubingSystem)arenowavailableforusewithdirectpushdrillingrigstoincreasesamplingefficienciesandreducepotentialissuesduetorodleakageandcontamination.Alternatively,dedicatedsoil-gassamplingpointscanbeinstalledforone-offsamplingorrepeatmonitoringevents.

SmallportableHgvapouranalysers,suchasthoseofferedbyJerome®(e.g.J405)orLumex® (e.g.RA915+),havebeenusedsuccessfullyduringsoilinvestigationsandsoil-gassamplingactivitiestoprovidereal-timequantitativeelementalHgvapourmeasurements.

Ifsorbenttubesareused,sulphide-activatedcharcoaltubesareconsideredtoprovidebetterdatathannormalactivatedcarbon21.ItshouldbenotedthatensuringreliablemeasurementsofHgvapourcanbe

Source: Geoprobe Systems


problematicinsomesoiltypesasthepumpratesonmanyinstrumentscandrawupmorevapourthanisreadilyreplenishedthroughthesoilpores,whichcanleadtooverlyconservativedatabeingusedinsubsequentexposuremodelling.UsingpassivecapturedevicessuchasthesidecellontheLumexcanhelptoavoidthis.

TheMembraneInterfaceProbe(MIP)hasalsorecentlybeendemonstratedtobeeffectiveinprovidingrapidreal-timeverticalprofilesofelementalHginsoilandsediment22.TheMIPismountedontoadirectpushriganddrivenintothesubsurface.Theheatedprobevolatilises

elementalHginthedirectvicinityandtheHgvapourpermeatestheMIP’sporousmembraneand is transported in an inert carrier gas to areal-timedetectoratthesurface.TheMIPprobetypicallyincludesatipthatmeasuressoilconductivityandotherparametersataknowndistancebelowthemembrane,whichcanhelptocorrelatecontaminantconcentrationchangesinsoilstratigraphy.

Ex-situ Characterisation Techniques and Sampling ConsiderationsPortableHganalyserscanbeusedfortheex-situscreeningofbuildinginfrastructureanddebris,aswellassolidorliquidenvironmentalsamples.Hand-heldvapouranalysers,suchastheLumex®orJerome®analysersdescribedabove,orotheravailablehand-helddetectorssuchastheIonScienceMVI,canbeusedtoscanthehead-spaceaboveasampleorsitefeaturesuspectedofelementalHgcontaminationorforthedirectanalysisofairorothergasstreams.Therearealsomobileanalysersavailableforthedirectanalysisofsolidorliquidsamplesinthefield.

Someofthemorecommonly-usedanalysersinEuropeforthefieldanalysisofsoil,debris,sediment,organicmaterialsandliquidsamplesincludetheJerome®J405,Lumex®RA-915+(withattachmentssuchastheRP-91,91CorPYRO-915+)andportableX-rayfluorescence(pXRF)analysersthatareavailablefromseveralsuppliers,includingThermo-Scientific(Niton),BrukerGmbH,OxfordInstrumentsandOlympus.Asummaryofthemainanalysersisprovidedinthetableonthenextpage.


Source: Geoprobe Systems

Table 1. Commonly-used Portable Hg Analysers

Instrument Name Manufacturer Analytical Method Range Reported

Interference Dimensions Image

Jerome®J405

ArizonaInstruments,LLC

Goldfilmsensor 0.5–999µg/m3

Noneidentified

2.4kg27.9x15.2x16.5cm

LumexRA915

OhioLumexCo. Atomicadsorptionspectrometer,Zeemancorrectionofbackground

0.05–200µg/m3

Noneidentified

3.3kg29.0x21.0x11.0cm

Mercury VapourIndicator (MVI)

Ion Science Dualbeamultravioletadsorptionmodule

0.1–200µg/m3

1.0–1999µg/m3

Nonereported 3kg14.5x29.5x8.0cm

NICEMP-2 NipponInstruments

Atomicadsorptionspectrometer

0.1to1000µg/m3

Nonereported 1.8kg26.5x12.8x11.0cm

TekranModel2537X

TekranInstrumentsCorporation

Goldtrappreconcentration withatomicfluorescencedetection

0.001to2µg/m3

Nonereported Weightnotreported48.3(w)x22.9(h)cm

DELTAHandheldXRF

Olympus X-rayfluorescence 2to4and10to15µg/m3

Nonereported 1.5kg(w/obattery)26×24×9cm

Source: Data obtained from the respective manufacturer’s published instrument specifications.


Thecurrently-availableportabledetectorsprovidevaryingdetectionranges,resolution,calibrationrequirements,accuracy,batterylife/powerrequirements,size/weight,interferenceissuesetc.,andshouldbeselectedbasedonthespecificprojectneeds,siteconditionsandregionalavailability.Forexample,thereisapotentialtoobtainfalsenegativeresultswhenusingpXRFdetectorstoscreenmaterialswithhighconcentrationsofelementalHg,duetothefactthatX-raysdonoteffectivelypenetrateHgdroplets.

Althoughdirectfieldmeasurementscantypicallybemadewithminimalsamplepreparation,itisoftenrecommendedthatsolidsamplesaredried,sieved,andhomogenisedbeforeanalysis.PreliminarytestsconductedbytheBRGMcomparingHgconcentrationsinsplitsamplesdriedinasmallnon-ventilatedovenat38°C(max)totheoriginalwet(non-dried)samplesshoweddifferenceswerelessthanthenormalobservedsampleheterogeneity.However,thepre-dryingallowedmoreefficientandeffectivesievingpriortoanalysis.(Properhealthandsafetyproceduresshouldbeimplementedduringsuchactivities).Analternativedryingmethodthatcouldbetested,wouldinvolveplacingthesamplewithinaclosedvolumeinthepresenceofanon-reactivewaterabsorbent(e.g.silicate,anhydrousCaCl2).

AsdescribedinSections2and3,identificationofthedifferentHgspeciespresentiscriticalforevaluatingthepotentialrisksposedbyasitetohuman-healthortheenvironmentandfordevelopinganeffectiveCSMandrisk-based

managementstrategy.Thisshouldbebackedupbyanalysesfocussedontheexposuremedia(e.g.ambientair)andmigrationpathways(e.g.soil-gas,groundwater,leachatesamples)toestablisharobust“lines-of-evidence”approachtotheCSM.

Additionally,asolidunderstandingofotherphysicochemicalparameters,suchaspH,total/dissolvedorganiccontent,grainsizedistribution,claycontent,redoxpotential,cationexchangecapacity(CEC),soilmoistureandironcontent,isimportantforevaluatingtheHgdistribution,fateandtransport.Thecollectionofsamplesforlaboratoryanalysisisthereforerecommendedinadditiontotheuseoffieldscreeningtechniques,inordertoobtainsufficientcoverageacrossthesiteaswellasthelowquantificationlimits,supportingparametersandHgspeciationdataneededforrobustsitecharacterisationandmanagement.Thesamplepreparationperformedinthelaboratorypriortoanalysis(e.g.drying,homogenization,grinding)isconductedundermore-controlledconditions,therebyincreasingthereliabilityandreproducibilityofthemeasurementscomparedtofieldscreening techniques.

Consideringthesefactors,theSNOWMANnetworkrecommendsatleastonelaboratoryanalysisforeverytensamplescollectedfortotalHg(andotherrelevantparameters),withasubsetofthosesamplesshowingelevatedHgconcentrationsalsosubmittedforspeciationanalysis18.AlthoughfewaccreditedanalyticallaboratoriescurrentlyprovideHgspeciationanalyses,BrooksAppliedLabsisalaboratory


AN UNDERGROUND SANDSTONE GALLERY USED TO STORE 80 METRIC TONS OF HG CONFISCATED FROM GERMAN ARSENALS DURING WWII. CORROSION OF STORAGE CONTAINERS RELEASED LARGE QUANTITIES OF HG INTO THE GALLERY AND CONTAMINATION OF GROUNDWATER SEEPAGE.

Source: ERM

Key learnings Arobustinvestigationofthegallery,andsurroundinggroundwater,surfacewater andsedimentwasconductedtoassesspotentialhumanandecologicalrisks.

Humanandecologicalriskassessmentssupportedapragmaticremediationapproachthatwasacceptedbytheregulatoryauthorities.

StringentH&Sprotocols,monitoringandtheuseofwell-trainedsub-contractorsallowedworkwithinthegallerytobesafelyexecutedwithnorecordableincidents.

Managementstrategyincludedremovalofpartsofgallerywallsandfloor,treatment ofwaterseepagewithpoly-sulphides,andimmobilisationoftheremainingelemental HgasHgS.

CASE STUDY 3: MERCURY WASTE CELL, GERMANY



intheUSthatprovidestracemetalsanalysisforsitesworldwide,includingHgspeciationthroughsequentialextraction23.

ThecollectionofsoilsamplesfromundisturbedsoilcoresispreferredtominimisepotentialHglossesduetovolatilization,andwhencollectingsamplesforlaboratoryanalysis,suitablelaboratory-suppliedsamplingcontainersandpreservativesshouldbeused.Polyethylenebottles,forexample,havebeenshowntoallowHglossesthroughvolatilization.Analysisofgroundwaterandsurfacewatersamplesshouldbeperformedonbothfilteredandun-filteredsamples,soastoassessHglevelsinbothdissolvedandparticulate/colloidalforms.

Other Impacted MediaMaterialcostduringtheremediationofHg-impactedsitesisoftenassociatedwithotherimpactedmedia,suchassludges,concrete,surfacewaterandsediments.AssessmentofthesemediaduringsitecharacterisationisessentialtoestablishafullCSM,robust

reservesandminimisetheriskofadditionalworksduringremediationimplementation.

Health & Safety Challenges During Site Characterisation ActivitiesThemainHgexposureroutesforhumanhealthareinhalationandingestion.Therefore,strictly-controlledsite-specificpersonalprotectiveequipment(PPE)andhealthandsafetyproceduresarecriticalduringsitecharacterisation(e.g.useofHg-specificrespirators,protectivesuits,fullskincoverage).Theuseofhand-heldvapouranalysersand/orambientairmonitoringstationsisalsorecommended.Stringentdecontaminationprocedures,wastehandling/disposalandgoodhygieneshouldbeimplemented.Ifthesiteislocatedwithinaresidentialareaornearsensitivereceptors,itmightbenecessarytoencloseworkareastopreventunacceptableairemissionsduringground-disturbingactivities.Routinemedicalmonitoring(e.g.urinetesting)isadvisablebefore,duringandafterinvestigationprogrammes.

Source: ERMSource: ERM

A LARGE CHEMICAL COMPLEX DEVELOPED IN THE 1960S AND CLOSED IN 2009, COMPRISING FORMER ACETALDEHYDE AND VINYL CHLORIDE PRODUCTION UNITS USING HG CATALYSTS.

Source: ERM

Key learnings Innovativeinvestigationtechniquesapplied,withHgspeciationbyBrooksAppliedLabs.ResultsshowedhighproportionofcomplexedHg,lowlevelsofHg0 and negligiblemethyl-Hg.

0.08% 4%

Mercure volatile

0.1%

96%Mercure complexeMercure solubleMéthyle de mercure

Noimpacttogroundwater,ambientair,oroff-sitesurfacesoils,surfacewater,orriversedimentsprovidedfurtherlinesofevidencefortheriskassessment.

Robustcharacterisationandriskassessmentfacilitatednegotiationoffavourable clean-upgoals:80%massremoval,acceptableriskforfutureindustrialuse.

Pan-Europeanbidprocessin2013toselectmostqualifiedcontractor.

CASE STUDY 4: ACETALDEHYDE PLANT, FRANCE


DevelopedarobustH&Scultureduringbidprocessandatstartofremediation worksandimplementedappropriatemonitoring(air&biological).

RateofexcavationwasslowerthanforotherpollutantstoeffectivelysegregatesoilsandavoidverticalmigrationofelementalHg.

Coarsealluvialdepositsallowedtheoptimizationofoff-sitedisposalvolumes/costsbymechanicalsorting(circa60%reductionindisposalvolumes).

ImpactedfineswerestabilisedanddisposedofintheBellegardelandfillin south-easternFranceordrummedandstoredintheUEVsaltmineinGermany.RecoveredelementalHgwasrefinedattheHgIndustriessiteinFrance.

Remediationcomplementedbyotherriskmanagementmeasures:coveringof residualconcentrations,deedrestrictions,salecontracts.

CASE STUDY 4: ACETALDEHYDE PLANT, FRANCE

Source: K+S entSorgung, gmbH, HeSSen, germany

Soil Groundwater

Most commonly

employed

Soilexcavation&off-sitedisposal(section5.1) Soilwashing(5.2) Solidification/stabilisation(5.3) Thermaltreatment(5.4)

Hydrauliccontainment(5.6)

Pump&treat(5.6)

Permeablereactivebarriers(5.6)

Funnel&gate(5.6)

Emerging and/

or unproven

In-situelectro-remediation(5.5)

Bio-treatment(Fixed-bedbioreactors)(5.5)

Phyto-extraction(5.5)

Immobilisedalgae(5.7)

Biochar(5.7) Chelatingagents(5.7) Nanotechnology(5.7) ChemicalReduction&stripping(5.7)

Copper/brassshavings(5.7)

5Ifsitecharacterisationandriskassessmentconcludethatmanagementmeasuresarerequiredtocontrolunacceptablerisks,theappropriateapproachshouldbedefinedviaassessmentofcost-benefitandsustainabilityindicators,takingintoaccountriskstohumanhealthandtheenvironmentandsite-specificconstraints,futuresite-useandstakeholderexpectations24,25.ThissectionpresentscasestudiesandasummaryofremedialapproachesthathavebeenappliedatHg-impactedsites,bothforin-situandex-situsoiltreatmentand

groundwaterremediation.Althoughthemainfocusofthissectionisonremediationtechniques,NICOLEhighlightstheimportanceofothertools(e.g.deedrestrictions,monitoring,robustsalescontracts)thatcanbeemployedtocomplementremediationandachievethemostsustainablemanagementapproachforHg-impactedindustrialsites.

Thesitemanagementtechniquescoveredbythisbookletaresummarisedinthetable below:

SITE MANAGEMENT TECHNIQUES

Table 2. Summary of Site Management Techniques Summarized in this Booklet


5.1. SOIL EXCAVATION AND OFF‑SITE DISPOSAL

Althoughsoilexcavationandoff-sitedisposalisalong-establishedremediationapproachforimpactedsites,theuniquepropertiesofHgmeanthatexcavationmethodologiesneedtoberefinedandtheoff-sitedisposaloptionsaremorelimitedandcostly.

Soil ExcavationExcavationofHg-impactedsoilsneedstobeperformedinacontrolledmanner,soasto:1)optimisesoilvolumesneedingoff-sitedisposal(theprimarycostforthisremediationapproach);and2)minimisetheriskofincreasingimpactedsoilvolumes,primarilybyavoidingcoalescenceanddownwardmigrationofelementalHg.

Full-timesupervisionofexcavationworksbytrainedpersonnelisadvised,asthisenablesvisualinspectionandsoilmonitoring(usingfieldinstruments–seeSection4)tooptimisewastevolumesbyeffectivesegregationofcleanandimpactedsoils.On-siteinstrumentsalsosupportthemitigationofHealth&Safetyrisksandvalidationofthebaseandsidesoftheexcavationspriortoconfirmatorylaboratoryanalysis.

SupervisingstaffshouldidentifyHg-impregnatedstructures(slabs,walls,foundations),whichhavethepotentialtore-contaminatesurroundingsoilsifleftinplace,andmaintaintheintegrityoflowpermeabilityhorizons(e.g.claylayers)topreventdownwardmigrationofelementalHg.TheyshouldalsodirectexcavationeffortstoimpactedhorizonsandpreferentialHg-migrationpathways(e.g.cracks/fissures,granularbackfill,rootlets),therebyminimizingexcavatedvolumesandtheremediationtimeandcosts.

Althoughlabour-intensive,manualremovalofelementalHg(e.g.usinghandtools,syringes,suctionpumps),whendiscoveredduringexcavation,istypicallycost-effective,asthepureHgrepresentssignificantmassanditwillreducethecostsofsoiltreatmentanddisposal.

ThecharacteristicsofHgandtheissuesdescribed above inevitably lead to longer excavationtimesthanforsoilsimpactedbyotherpollutants.However,ifthesebestpracticemeasuresareemployed,thevolumesofsoilrequiringtreatmentandoff-sitedisposalcanbemateriallyreduced,leadingtolowerremediationcosts.

5. SITE MANAGEMENT TECHNIQUES

Source: ERM Source: ERM

Asexcavationformsthebasisforallex-situtechnologies,thecarefulcontrolofexcavationandminimisationofwastevolumesareequallyapplicableduringtheearlyphasesofbothsoilstabilisationandthermalremediationprojectsdiscussedinsubsequentsections. Awellthoughtoutprojectplanisessentialtoensurethattheexcavationworksproceedinanorderlymanner.TheneedforrobustHealth&Safetycontrols,includingappropriatePPE,airmonitoringandregularmedicaltesting(includingbaselinetests)isalsoanimportantaspectduringtheworks,andspecificplansshouldbepreparedtoidentifyrisksandimplementappropriatemitigationmeasures.

On-site treatment before off-site disposalIfgranularsoilsarepresent(e.g.alluvialdeposits),soilsorting(e.g.bygriddlebucket,hydrocycloneormechanicalscreener)canmateriallyreducesoilvolumesrequiringoff-sitedisposal,asHgistypicallyconcentratedinthefinersoilfraction.AircaptureandtreatmentshouldbeconsideredtominimiseHg-impactedairemissionsfromthetreatment.MechanicalscreeningofHg-impactedsoilsduringremediationoftheacetaldehydesiteinFrance(seeCaseStudy4)reducedvolumesofwastesoilrequiringoff-sitedisposalbycirca60%.

Toensureacceptanceatsomeoff-sitedisposalfacilities,otherformsofpre-treatmentcanbenecessarypriortoconsignmentofthewastematerials.AsdescribedfurtherinSections5.2and5.3,severaltreatmenttechnologieshavebeenpatented,trialledortakentofullimplementationforthispurpose.Themajorityofthesetechnologiesaimtosolidify/stabilizethematerialsbyconvertingelementalHgandHgcompoundsintostablesulphide-richformsofHg.

Off-site treatment/recovery and disposal facilitiesAsmentionedpreviously,off-sitedisposalrepresentsthemaincostassociatedwiththisremediationapproach,typicallyrangingfrom250-500€/T,orpotentiallyhigherforheavily-impactedmaterials.

IflimitvaluesforHgrelatingtoleachtestingcanbeachieved,thenlandfillingwithinanappropriateclasslandfillisanapplicabledisposalroute.Duringtheremediationworksperformedin2014(CaseStudy4),theBellegardeLandfilloperatedbySITAFDwaspermittedtoacceptpre-stabilisedHg-impactedsoilswithleachableHgofupto0.2mg/l,whichcorrespondedtocirca5000mg/kgtotalHgatthesiteinquestion.ThesesoilswerestabilisedattheBellegardesitepriortodisposaltoaspecificlandfillcell.

OthertreatmentanddisposaloptionsavailablewithinEuropeformoreheavily-impactedmaterialsaresummarizedinthetableonthenextpage.

Source: ERM


Company Location Description Comments Web Address/Contact Information

Offsite Disposal

SITAFD Bellegarde,France

Hazardouswastelandfill

Acceptsoil/debris.NoliquidmetallicHgandnoradioactivewaste.Hgthresholdsof5000mg/kgtotaland2mg/kgleachable.OtherthresholdvaluesonTOCandmetalsalsoapply.

+330466011383

Minosus(VeoliaEnvironmentalServices)

Cheshire,UK

Undergrounddisposal in industrial salt mine

Acceptsoil/debris,butcannotacceptliquids(includingliquidmetallicHg),sludges,gasesorradioactivewaste.Wastemustbenon-flammable,non-explosive,non-volatile,non-odorous,non-deliquescent,non-radioactiveandnon-reactiveuponexposuretoair,saltormoisturewithinthemine.TotalOrganicCarbon(TOC)thresholdof3%andthefacilityconductsbiodegradability testing prior to acceptance.

http://veolia.co.uk/

Umwelt,EntsorgungundVerwertungGmbH(UEV)

Heilbronn,Germany

Undergrounddisposal in formersaltmine

Acceptsoil,debris,butcannotacceptliquidsorwastewithsignificantfreemoisture.NoliquidmetallicHgandradioactivewasteisgenerallyrefused.

http://www.uev.de/

K+SEntsorgung,GmbH

Hessen,Germany


Acceptsoil/debris,butcannotacceptliquidsorwastewithfreemoisture(includingHgdroplets).NoliquidmetallicHgandnoradioactivewaste.Hgthresholdof5%Hgbyweight.Materialswouldberefusedifmethyl-Hgispotentiallypresent.

http://www.ks-entsorgung.com/

GlückaufSondershausenEntwicklungs-undSicherungsgesellschaftmbH(GSES)

Sonder-shausen,Germany


Acceptsoil,debris,butcannotacceptliquidsorwastewithsignificantfreemoisture.NoliquidmetallicHgandradioactivewasteisgenerallyexcluded.

http://gses.de/

MiljøteknikkTerrateamAS

MoiRana,Norway

Undergrounddisposalinrockcavernsofformersteelworks

Facilityhasapermittoreceive70,000metrictonsofinorganichazardouswasteperyear.Thewastemustbestabilised/solidifiedbeforeplacementintotherockcavern.Maximumallowedleachingof0.01mgHg/lbasedontheUSTCLP63test.

http://www.terrateam.no/

NOAH LangøyaIsland,Norway

Stabilisationwithlimeandgypsumand disposal belowsealevelinformerlimestonequarry

Accepthigh-concentrationwaste(>1000mg/kgHg),butnotliquidmetallicHg.UpperTOClimitof1%forhigh-concentrationwasteand5%forless-contaminatedwaste.NICOLEexpressesconcernaboutthehydrologicalandhydrogeologicalsettingofthisfacility(photobelow).

http://www.noah.no/


Table 3. Treatment and Disposal Facilities for Highly-Impacted Mercury Contaminated Waste

Company Location Description Comments Web Address/Contact Information

Offsite Treatment

NordischeQuecksilberRückgewinnungGmbH(NQR)/Remondis

Dorsten,Germany

High-capacitythermaldesorption/ recovery

FormerDELAfacilityrecentlyacquiredbyRemondisandisundergoingre-startup/permitting.Previouslyabletoacceptlargevolumesofwaste(e.g.commercialproducts,soil,debrisandfreeelementalHg).Dioxinspossiblyanissueandtestingrequired.

http://www.remondis-industrie-service.de/ris/loesungen/nqr-mercury/

HgIndustries(Aurea) Voivres-lès-le-Mans,France

Batchthermaldesorption/ recovery

FormerMBMfacility.Typicallyhandlesshipmentsof20-25tons(max)high-concentrationwaste(e.g.commercialproducts,soil,debris,andliquidmetallicHg).

+33679013625

BATRECIndustries(VeoliaEnvironmentalServices)

Switzerland Batchthermaldesorption/ recovery

Typicallyhandlesshipmentsof1-50tonhigh-concentration(>10,000mg/kg)waste(e.g.batteries,soil,debris,andfreeelementalHg).

+33637031265

GesellschaftfürMetallrecyclingmbH(GMRGmbH)

Leipzig,Germany

Batchthermaldesorption/recovery as wellasanimmobilisationprocesswithgeopolymers

Typicallyhandlessmallbatchesofslurries,sludgesandotherresiduescontaining natural radioactivity and/orHgaswellasfreeelementalHg.

http://www.gmr-leipzig.de/

OphramLaboratoire SaintFons,France

Batchthermaltreatment/Hgrecycling

SpecializesintherecyclingandrefiningofpuremetallicHg.Supplieshigh-purityHginsealedampoulestomicroelectronicsandoptronicssectorforsemiconductorproduction.

http://www.ophram.com/

Specialpackagingandhandlingrequirementsarerequiredformostofthedisposalfacilitieslistedabove,includingtheuseofsealeddrums,bulkbagsorsteelcontainers. Giventhehighcostandrelativelylowthrough-putofseveralofthebatchthermaltreatmentandrecoveryfacilitieslistedinTable3,theyaretypicallyonlyusedforrecoveredfreemetallicHgand/orthemosthighly-impactedsoilsandwastethatcannotbeacceptedinotherstorageortreatmentfacilities.Atthetimeofpublicationofthisbooklet,theformer

Source: K+S entSorgung, gmbH, HeSSen, germany

http://www.uev.de/

http://www.noah.no





http://www.gmr-leipzig.de/gbindex.htm

http://www.gmr-leipzig.de/gbindex.htm


high-capacityDELAthermaldesorptionfacilityinDorsten,Germany,hadbeenacquiredbyRemondisandundergoingpermitting/start-upasNordischeQuecksilberRückgewinnungGmbH(NQR).Onceoperational,itisanticipatedthatthisfacilitywilllikelyofferalower-cost,higher-capacitytreatmentoptionforhighly-impactedHgwastes.

Cross-Border Waste ShipmentsAnotherimportantconsiderationwithrespecttowastehandlingiscompliancewithexportrequirementsduringcross-bordershipmentofwastestotheirfinaldisposalsite.Chlor-alkaliproducershavealegalresponsibilityunderECDirective1102/2008toreporttheamountof>95%pureHgrecoveredduringthedecommissioningofchlor-alkaliplantsv.ToarrangeexportandcomplywiththeEUWasteDirective2008/98/EC,theconsigneemustapplytothecompetentauthorityofthecountrywherethewasteisproducedandobtainconsentfromtherelevantexportingandimportingcountriesandpayanyfees.In2007,closeto700000Tofwaste(codedas170503-Contaminatedsoilandstones)wastransportedacrossEUborders,withthebiggestrecipientbeingGermany.

Due Diligence of Disposal / Treatment FacilitiesAppropriateduediligenceisrecommendedwhenconsideringoff-sitetreatmentanddisposalfacilities.Keyquestionstoanswer include:

Isthefacilityfullypermittedtoacceptyourwastematerials?

Doestheoperatorofthefacilityassumefullresponsibilityforthewaste?

Ifcross-bordertransferisrequired,doesitcomplywithEUDirectives?

Forlong-termstoragesolutions,howgeologicallysecureisthefacility?

Fortreatmentfacilities,whatdoesthefacilitydowiththerecoveredHg?

5.2. SOIL WASHING Soilwashingtechniquesutilisephysicaland/orchemicalprocessestoreducetheHgcontentinsolidmaterials(soil,sedimentorsludge).Therearethreecommonly-usedapproachestosoilwashing.Themostcommonisparticle-sizebeneficiation.Thisisbasedonthepremisethatcontaminationisassociatedwithsurfacearea.Fine-grainedmaterialshavethegreatestsurfaceareaandthereforethehighestconcentrationofcontaminants.Separationofthefinesfromthecoarserfractions(whichgenerallyhavelowercontaminantlevels)cansignificantlydecreasethevolumeofsoilrequiringtreatmentand/ordisposal.ThesecondapproachoftenusedforHg-impactedsoils,especiallymaterialsimpactedwithelementalHg(Hg0),isdensityseparation.ThedensityofelementalHgis13.5g/cm3comparedtothedensityofsoil,whichisgenerallyabout2to3g/cm3.ThisdensitydifferenceprovidesabasisforseparatingelementalHgfromsoilandreducingtheoverallmassofmaterialrequiringtreatment/disposal.ThethirdapproachcompriseschemicalleachingofHgfromthesoil.Forthisapproach,liquidsolutionssuchasnitricacid,hydrochloricacidandpotassiumiodide/iodineareusedtoremoveHgfromthesolidmatrix.


ComprehensiveinformationregardingtheoriginoftheHgimpactswillprovideagoodbasisforunderstandingthespeciesofHglikelypresentatasite.However,itisimportanttoconsiderthatthephysicochemicalnatureofthecontaminationcanchangeslowlyovertimeduetovariousphenomenalikeoxidation,complexation,methylation,adsorption,etc.TheHgspeciespresentandthephysicochem-icalnatureofthesoilwillstronglyeffecttheefficiencyofatreatmentprocesssuchassoilwashing28,29,30,31.

Summary of Recent Soil Washing Projects ConventionalphysicalseparationtechniquesarethemosttypicallyappliedinEuropeandNorthAmerica,comprisingstepssuchasscreening,sieving,hydrocycloning,attritionscrubbing,frothflotation,magneticseparation,etc28.Thesetechniquescanberelativelysimple,andthereforecost-efficient,asprovenbytheextensivetrackrecordinthelast25years.Physicochemicalsoilwashingtechniques,includingchemicalextraction,entails(simpli-fied)hydrometallurgicalmethods,generallymakingthemmorecomplex,lowerinthrough-putandcurrentlymoreexpensive29,32,33.Thisisreflectedinthescarcenumberofprojectsandtheirsmallsize,oftenatpilotscaleonly.

Theexistenceofcompetitivesolutions,suchascontrolledlandfilling(uptoconcentrationsof5,000mg/kgHginEurope)andspecificthermaltreatmenttechniques,imposeafinancialboundaryconditionontheapplicabilityofsoilwashingforHg-impactedsoils.Practicallythismeansthatconventionalsoilwashingtech-niquesaretypicallyappliedprimarilyforthe

removalofelementalHg,forwhichbespokewashingplantshavebeendesigned.

In1993,approximately10,000m³ofcoarsesandysoilimpactedwithvariousmetalsincludingHgwastreatedbywashing(con-sistingofscreening,hydrocycloning,attritionscrubbingandfrothflotation)attheKingofPrussiasuperfundsite(NewJersey,USA).Throughputoftheplantwas25Tanhour.Althoughitisdescribedintheprojectreportforthissite33thatHgconcentrationscouldbereducedfrom100mg/kgto1mg/kg,thereportdoesnotprovideanyactualperformancedataregarding Hg.

Duringtheremediationofaformerchlor-alkaliplantoperatedbyNexusinBritishColumbia,Canada,approximately24,000Tofsoilwerereportedlytreatedbywashingbetween1999and2003.Thesoilwashingplanthadacapacityof14Tanhour,andreducedtheHgconcentrationdownto40mg/kg.Theinitialconcentrationswerenotspecified.TheprocessusedatthissitewasreportedlythebasisfortheOricaBotanytransformationprojectin Australia33.

Aformerchlor-alkaliplantnearSyracusewasidentifiedasoneoftheprimarysourcesofcontaminationtotheOnondagalake(NewYorkState,USA).ConcentrationsofelementalHgupto19,000mg/kgwerefoundinsoilatthissite.In2003,about8,500Tofsoilweretreatedbysoilwashing,whichreportedlyremovedabout7TofHg.However,notechnicaldataregardingthesoilwashingplantorthesoilcompositionwere published.


DuringtheremediationoftheformerEKAchlor-alkalisiteinBengtsfors,Sweden,in2007,largevolumesofHg-impactedgravelswerefound.Theseweretreatedon-sitebysimpledrumwashingofthefraction>20mm,withathroughputof100Tanhour.There-usetargetwas5ppm.Althoughtheundersizedfractionwaspotentiallywashable,theenvironmentalpermitdidnotallowon-sitewashingandtheundersizehadtobelandfilled.Therecycledoversizefractionmadeupabout70%ofthetotalsoilvolume31.

In2010,13,000Tofsandysoilwerewashedoff-siteinatreatmentcentreinAntwerp.ThesoilcamefromaformerfeltproductionsiteinLokeren,Belgium,andwasimpactedbyHg,mainlyintheformofHgnitrate.InitialHglevelsofupto50mg/kgwerewashedtobelow5mg/kg.Asexpected,theremovalefficiencyofhighlywatersolubleHgnitratesaltwashigh.

Aftersomeyearsoflaboratoryscaleandpilottesting,abespokesoilwashingplant(simplescreening,drumwashing)wasbuiltfortheOricaproject(BotanyBay,Australia)34.Theplantwaserectedinahallwithairextractionandmonitoring.Theformerchlor-alkalisitewasheavilyimpactedwithHg(80to15,000mg/kgHg).Theplanthadtostopoperationsafteronlyafewmonthsofproductionin2011.Thespecificreasonsforstoppingtheplantwerenotpublished,butissueswithHgvapouremissionsandpoorperformancearementioned.Only2,900Tofsoilweretreated,1,350Tre-used,and1.2TofHgremoved.Thetreatmenttargetlevelwas70mg/kg.

Aformerchlor-alkalisiteoperatedintheNetherlandscontained60,000Tofimpactedsandysoil,withHglevelsupto1,200mg/kg34.ExtensivelaboratoryresearchshowedthatreductionsinTotalHgconcentrationsbetween70and80%couldbeachievedthroughsoilwashing.Althoughthere-usetargetwassetatarelatively-low7mg/kgtotalHg,itwasdecidedtocarryouton-sitesoilwashingwiththeaimofrecyclingasmuchsoilaspossible.Intotal,20,000Tofsoilwerewashed.Althoughthelab-scaleremovalrateswereachievedinthefull-scaleprocess,only3,000Tofthewashedsoilmetthe7mg/kgtarget.

DuringthebiddingprocessfortheremediationofanHg-impactedsiteinFrance,lab-scalesoilwashingtestswereconductedbyDEC(partofDEMEGroup).Thesitesoilconsistedmainlyofgravel(55%)andsand(35%),with10%finematerials.Initialconcentrationsweregenerallyintheorderof100to10000mg/kg,withsomevisibleHgdroplets.Duringthetest,thegravelwaseffectivelyseparatedandwashedtobelowtheestablishedre-uselevels(28mg/kg).However,cleaningthesandfractionwasmoredifficult.Theoperatoroptedforadrygravelsortingprocess,withsandandfinematerials

Source: DEC (subsidiary of DEME Environmental Contractors)


consideredasresidueandlandfilledoff-site.Laboratorytestscarriedoutonsoilsfromseveralsources,mainlychlor-alkalifacilities29,30,35,typicallyshowthatmediumtohighconcentrationsofelementalHg(100to10,000mg/kg)insandcouldbeeffectivelyreducedtobelow50mg/kg.Furtherdecreasesrequireintensiveconventionalsoilwashingsteps(e.g.attritionscrubbingorfrothflotation)and/oralternativetechniques(ultrasonicscrubbingorchemicalcomplexation).CharacterisationoftheresidualHgafterphysicalwashingbyvisualinspectionormicroscopyandbysequentialleachingtestsshowedthatmicroscopicHgdropletswereabsorbedwithinfissuresofthesandgrains,andsomeHgoxideswerestillpresent.

ConclusionsPhysicalsoilwashingcanmateriallyreduceHgconcentrationsinsoil,withthegravelfractioneffectivelycleanedtorelatively-lowconcentrations.Thesandfraction,however,isgenerallymuchmoredifficulttotreat,andrequiresintensivetechniques(e.g.scrubbing,flotation,chemicalcleaning)inordertoreachconcentrationsof10–20mg/kgtotalHg.Aswithanysoilwashing,thefines(clay+siltfraction)shouldbebelowabout30%ofthetotalsoilmass.

Adisadvantageofsoilwashingisthattheresidueoffines(filtercake)canbeveryconcentratedinHg,makingitdifficultandexpensivetotransportanddisposeoff-site.

ForHgimpactedsites,twotypesofsoilwashingapplicationscanbeconsidered:

firstlyreducingelementalHgconcentrationstomoderatelevels,forexamplebelow1000mg/kginEuropetoallowlandfilling.Secondly,moreintensivesoilwashingcanreduceHgconcentrationstolowerlevels(10-50mg/kg),whichisoftensufficienttocomplywithsite-specificrisk-basedstandards.

5.3. STABILISATION / SOLIDIFICATION

Stabilisation/solidification(S/S)isafrequently-usedtechnologyforthetreatmentofHg-impactedsoilandwaste28.AwiderangeofHg-impactedmaterialcanbetreatedbyvariousS/Sprocesses,includingsoils,sludge,liquidwastes,industrialwasteandelementalHg.Stabilization/solidificationcanbeappliedeitherinsituorexsitu,althoughitismostcommonlyimplementedexsitu.

Stabilization/solidificationisawell-establishedremediationtechnologyintheUSA,JapanandseveralEuropeancountries.Itoriginatesfromtheconstruction,miningandnuclearwasteindustriesandwaslaterappliedtosoilremediation.TheuptakeofS/SasaremediationtechniqueinEuropewasrelativelyslowcomparedtoothertechnologiespriortoenactmentoftheEULandfillDirective,mainlyduetothelackoftechnicalguidance,performanceuncertainties,previouspoorpracticeandpotentialresidualliabilities.IntheUK,forexample,thischangedfollowingthepublicationofguidancefromtheEnvironmentAgencyin2004supportingarisk-basedframeworkforthemanagementofland contamination.


ApplicationofS/Stoimpactedsoilsandwastesissupportedbyabodyofscientificevidencegatheredoverseveraldecades,andHg-specifictechniquesandinnovationsarecontinuingtobedeveloped.Stabilization/solidificationcanbeusedonitsownorcombinedwithothermanagementapproachesaspartofaremedialstrategy.However,thedifferentspeciesofHgcan,undercertainconditions,displaycomplexbehaviourpresentingpotentialchallengestotheuseofS/S.

AsignificantproportionoftheavailableliteratureisfocusedontheS/Sorpre-treatmentofHg-containingwaste(includinghazardousandradioactivewaste)forlandfilldisposal,ratherthanre-useonsite.Althoughthisresearchmeritsconsideration,thereviewprovidedhereinfocussesonS/StreatmentofHg-impactedsoils.

Stabilization/solidificationreliesonthereactionbetweenabinderand/orreagentwithsoil/wastetoreducecontaminantmobility.Thesetechniquesdonotreducethecontaminantconcentration,butinsteadreducesitsmobilitythroughchemicalorphysicalchanges.ThekeyS/SprocessescurrentlyusedforHg-impactedsoilsinclude:

Stabilisation–involvingtheadditionofreagentstoanimpactedsoiltochemicallyfixthesolublespecies,producingamorechemicallystable,lesssolublematerial.

Solidification–involvingtheadditionofbinderstoaimpactedsoiltochangeitsphysicalnatureinordertocontainorencapsulatecontaminantsintoasolidandrobustlow-permeabilitymatrix.

Amalgamation–consideredasub-setoftheS/Stechniques,andinvolvingthedissolutionofHginothermetals(e.g.copperorzinc)andsolidificationtoformanon-liquid,semi-solidalloycalledanamalgam.Thetechniqueisalsocommonlyusedtosupplementmoretraditionalcement-basedS/Stechniques39,40.Hgstabilisationwithsulphurorsulphurpolymercement(SPC)isalsosometimesreferredtoasamalgamation41.However,combiningHgwithsulphurresultsinHgsulphide,astableioniccompound,notanamalgamoralloy42.

Bench-scaletestingfollowedbypilot-scaleapplicationareimportantelementsofthedesignprocess,therebyprovidingconfidenceinfull-scaleoperation.


Source: ancHor Qea, LLc

Stabilisation / Solidification TechniquesArangeofex-situandin-situtechniqueshavebeensuccessfullyappliedforS/SofHg-impactedsoils,althoughex-situmethodsaremorecom-monlyused38.Mobileplantandreagentdeliverysystemscanbeconfiguredtomeetmostsiteconditionsanddelivertherightmixofbindersandreagents.However,severalS/SreactionscanpartiallyvolatiliseHgandsorequireade-quatecontrolmeasuresandassociatedhealthandsafetyprecautions.

Comparedtoin-situS/Stechniques,ex-situtech-niquescanbemoreonerouson-sitewithsev-eralmaterialhandlingstagesneeded,butcanprovidehigherproductionrates,betterqualitycontroloverbinderdeliveryandmixingandimprovedverificationofthestabilisedmaterial.ThisisespeciallyimportanttoensurecompleteencapsulationintheS/SmaterialofelementalHg,whichisdenseandcanbedifficulttomix.

Physicalpre-treatment,includingprocessingandscreening,canbeaneffectivefirststeppriortoex-situstabilisation,soastoprepareahomogenisedmediumandoptimisemixing,andtoconcentratetheHgcompoundsgiventheiraffinityforthefinersoilfractions.WetscreeningisnotrecommendedpriortoS/S,asthedenseHgdropletscanbehaveasaseparateliquid phase43.

RecoveryofelementalHgpriortoS/Sapplica-tioncanbeadvisabletoreducecontaminantloading,especiallywhenon-sitere-use/retentionofthetreatedmaterialisplanned.BreakinguplargerHgglobulestoprovidealargersurfaceareatoreactwiththebinder/reagentisanotherkeypre-treatmentstep.SometechnologiesincludeamechanicalsystemforbreakingtheelementalHgintofinesphericalparticles(prills)44.Asdescribedbelow,asuitablereagent(e.g.sodiumsulphide)canalsobeinitiallyaddedtoproduceeitherHgoxidesorHgsulphidesandoncemixedsufficiently,thecementisadded45.

In-situstabilisationiswellestablishedingeotechnicalapplications,forwhichspecialisedinjection/mixingequipmenthavebeendevel-oped.However,in-situmixingorinjectionislessestablishedforenvironmentalapplication,ashomogenoustreatmentcanbedifficulttoensure and validate44.Thesetechniquesaremostoftenusedtostabilisesludgelagoons,deepersoilcontaminationorsoilunderinfra-structures.Itcanproducea“monolith”intheground,whichneedstobecarefullydesignedtoavoidlocalisedfloodingandtominimiseconstraintsforfuturesite-use.Thisapproachcontinuestobedeveloped,asdemonstratedbysomecasestudiespresentedinNICOLE’sSummaryReport9andtheUSEPA28,includingtheuseofinnovative nanoparticles.

In situ stabilisation of sediment and soils impacted with Hg and PAHs in a former effluent treatment pond using binder agents. Source: ARCADIS


TreatmentratesforS/SvarysignificantlybasedontheformofHgpresent,andthenumberofprocessesandreagentsused.However,ratesof300to600m3perdayshouldbeachievable.Rateswherechemicalprocessessuchasamalgamationareundertakenmaybeconsiderablylower.

Binders and ReagentsSeveral binders and reagents can be used in theS/SofHg-impactedsoilsandwaste(USEPA28).ThemostcommonlyusedincludePortlandCement,enhancedbyadditionalbinderssuchasgroundgranulatedblastfurnaceslag(GGBFS),pulverisedflyash(PFA),asphaltorbitumen44.Elementalsulphurandvarioussulphideadditiveshavealsobeenused successfully43,67,69.

SomeelementalHgandorganicHgcompoundscanprovedifficulttostabiliseandadditionalchemicalorphysicalpre-treatmentisneededtoensureeffectiveS/S.Commonstabilizingagentsincludeelementalsulphur,sodiumsulphate,reactivatedcarbon,orferric-ligninderivativespriortosolidification.45,46,47.OtheradditivescontainingsulphursuchasGGBFShavealsobeensuccessfullyapplied.Withadequateblending,suchadditiveshavebeenshowntosuccessfullyconverttheHgcompoundsintolesssolubleforms,suchasmercuricsulphide(cinnabarandmetacinnabar)68.

ThetwomainchemicalS/SapproachesappliedtosoilsorwastescontainingelementalHgare:1)conversionoftheelementalHgtoHgsulphide;and2)amalgamation.Some

techniquescombinebothandincludetheuseofacement-basedmixenhancedwithGGBFSandcopperpowder40,41.

Theratioofbinders/reagentstosoilwilldependondetectedconcentrationsandthesoil’schemicalcomposition(i.e.Hgspecies,butalsoothercontaminantsornaturally-occurringsubstancesthatcouldinterferewiththeS/Sprocess).Thechoiceofbinder/reagentshouldbesite-specific,andsubjecttobenchtestsandpilottrials.Severalcasestudiesrelatingtolaboratoryandsite-scaleapplicationsareprovidedbytheUSEPA28andGRS40.

Thechoiceofbinder/reagentandthedosageusedwillleadtovariablestabilityofthematerialstreatedandalsoinfluencethecuringtime,compressivestrength,costsandtreatmentprocessappliedon-site28.

Influencing Factors and ConsiderationsKeyfactorscommonlyaffectingtheeffectivenessofS/Sincludegoodcharacterisationofthematerialstobetreated,selectionofthebestbinderandreagent,effectivecontactbetweenthecontaminantsandbinder/reagent,goodphysicalandchemicalconsistencyoffeedstock,appropriatemixingequipmentandbinderdelivery,controloverexternalfactors(e.g.temperatureandhumidity)andthecontrolofotherinhibitive substances.

TheapplicabilityofS/StotreatHg-impactedsoilsdependsontheHgspeciespresent,itsmobilityandconcentrations,togetherwiththesoilpHandmoisturecontent48.Thepresence


ofmorethanoneHgspeciesmaycomplicatetheprocessandreducetheeffectivenessunlesscharacterisedanddesignedappropriately.Typically,thesolubilityofHgincreasesinmoreacidicconditions,althoughsomestudiessuggestthatsomesolubleHgcompounds(e.g.Hgsulphate)mayformathigherpH49.

Certainnon-HgcompoundsinthesoilmayalsointeractwiththeS/Sreagents,thusaffectingtheirperformance.Forexample,highconcentrationsofchloridemayrenderphosphateadditivesineffective50.Forcertainbinderstobeeffective,thetreatedmaterialneedstohaveaspecificmoisturecontentandthereforematerialmayneedtobepre-treatedtoadjustthemoisture.

Typicaldosesforbindersare5to15%oftheHg-containingsoilsbyweight.However,doseswherehighlevelsofelementalHgarepresentcanbehigher.

PerformanceTheperformanceofS/Sinsoilsisoftenlinkedtomeetingrisk-basedremedialtargetsassociatedwithleachabilitytestingandalsophysicalstrengthtestsiftheS/Smaterialistobere-usedon-site.However,thereislittleprecedenceofS/S-treatedHg-impactedsoilsbeingre-usedon-site(unlessin-situtechniqueshavebeenapplied)andassuchthestrengthtestingrequirementsmaybeoflessimportance.Theleachateperformanceofex-situS/S-treatedHg-impactedsoilsisregularlylinkedtomeetinglandfillacceptancelevels.

SuccessfulS/Spre-treatmentofHg-impactedsoilsintheUSandCanadaarereportedtoregularlymeettheassociatednon-hazardouslandfillleachabilityacceptancecriteriaof0.025mg/land0.2mg/l,respectively.Forcomparison,theEuropeanWasteAcceptanceCriteria(WAC)leachinglimitsusingBSEN12457-3:2002atacumulativeliquid:solidratioof10forgranularwastesforinert,non-hazardousandhazardouslandfillsare0.001mg/l,0.02mg/land0.2mg/l,respectively38.

Variousbenchandsitetrialcasestudies28,40 showthatHgconcentrationsinsoilof1,000to4,000mg/kgcanbesuccessfullytreatedbyS/S,achievingleachableconcentrationsbetween0.002mg/land0.0139mg/l(usingtheToxicityCharacteristicLeachingProceduretest).Celtic(wholly-ownedsubsidiaryofEnGlobe)haveperformedin-houseteststhatfoundthatmaterialwithupto200mg/kgtotalHgisreadilystabilisedandcouldbere-usedon-site.

TheMercuryAmalgamationStabilization/SolidificationwhitepaperpreparedbytheOakRidgeNationalLaboratory41 provides a comprehensivediscussionoftheimpactofelementalHgspikes(upto10,000mg/kg)onleachateandtheperformanceofvariousslag-cementbasedbindersandreagents.

Long-Term PerformanceAlimitationinthepublishedliteratureisanapparentlackofappropriatelong-termdataonthechemicalbehaviourofHg-impactedsoilstreatedbyS/S,particularlywherethematerialhasbeenincontactwithwater.In-situtechniquesthatcreatemonolithsintheground


maymeettheiragreedleachabilityremedialtargets,butconsiderationofthelong-termperformanceoftheS/Smaterialremainstobetested.ThereisasignificantamountofperformancedataforotherS/Smaterials,whichsuggestthatHg-containingmaterialsshouldbestableinthelong-term.However,thisisanarearequiringfurtherresearchinreal environments.

Thecurrentunderstandingoflong-termperformanceisgenerallybasedonpredictivemodelsfocusedonleachingmechanismsandhavebeenappliedtoHgwastes,storedeitherinlandfillcellsordedicatedstoragefacilities.However,thesemodelsarestillbeingdevelopedandrefined.Theyarebecomingmoresophisticatedtoconsiderthecomplexity

ofcontaminatedsoilsandnumeroussite-specificfactorsthatcouldaffectthelongtermperformanceoftheS/Sprocess.

ThecredibilityofS/StreatmentofHg-impactedsoils,aswithallremediationtechnologies,isdependentonthoroughdesign(includinginterpretationofsiteorre-useconditions),benchorpilottrials,optimisedon-siteapplicationandverificationreportingtodemonstrateclearlinesofevidencebasedontheworksundertaken.Inparticular,confidenceinthelong-termperformanceandtheuseofcredibleverificationprocessesareessentialwhenusedaspartofarisk-basedremediationstrategy.


0,0000

0,0001

0,0010

0,0100

0,1000

1,0000

10,0000

10 60 70

Sample P13-1 Leachate Concentrations vs Time

Leac

hate

Con

cent

rati

ons

[Log

mg/

L/da

y

Time [Days]

Leachate Concentrations[Log mg/L/day]

Mix 1

Mix 2

Mix 3

20 40 5030

Source: Celtic (subsidiary of EnGlobe)

A FORMER PULP AND TISSUE MILL OPERATED FROM 1926 TO 2007, INCLUDING A FORMER CHLOR‑ALKALI PLANT. THE SITE IS SITUATED ADJACENT TO A MARINE SHORELINE IN A POPULATED AREA, AND IS PLANNED FOR MIXED‑USE REDEVELOPMENT. IN THE CHLOR‑ALKALI PORTION OF THE SITE, THE REMEDIAL INVESTIGATION IDENTIFIED SHALLOW GROUNDWATER AND FILL SOILS THAT WERE IMPACTED WITH HG, AS WELL AS A COMPARATIVELY SMALL VOLUME OF HIGHLY‑IMPACTED VADOSE ZONE SOIL CONTAINING FREE‑PHASE HG IN LOCATIONS WHERE ELEMENTAL HG WAS PREVIOUSLY HANDLED.

Key learnings Supportedbylaboratorytreatabilitytesting,on-sitestabilizationandoff-sitelandfilldisposalwasselectedasthefarmorecost-effectiveoptionrelativetooff-sitethermaltreatmentformanagingthehighly-impactedsoilscontainingfree-phaseHg.

Bench-scaletestingevaluatedtheeffectivenessofS/SwithPortlandcement,Portlandcementwithelementalsulphur,andPortlandcementwithferroussulphate,includinganevaluationofHgvapourreleaseduetoheatgenerationduringstabilization(cementhydration).TheresultssupportedtheselectionanddevelopmentofanoptimizedS/SprotocolusingPortlandcementwithelementalsulphurforfull-scale application66.

Source: Anchor QEA, LLC

CASE STUDY 5: PULP AND TISSUE MILL, WASHINGTON STATE, USA



Full-scaleapplicationofS/SusingPortlandcementwithelementalsulphurachievedtherequiredtreatmentstandardsforoff-sitelandfilldisposalwithoutexception(166individualtreatmentbatches).

SubsurfaceimpactsfromcausticsolutionsresultedingeochemicalconditionsfavoringeitherelevatedHgconcentrationsingroundwaterorsoil(buttypicallynotboth),asHgmobilityingroundwaterincreasesathighpHwhilesoiladsorptionanduptakedecreases.Indown-gradientareaswherethegroundwaterpHvaluesdecreasetowardsneutral,dissolvedHgconcentrationsalsodeclinebutsoilconcentrationsincrease.

Furtherbench-scaletestingevaluatedamendmentsfortheirHgremovalefficiencyfromhighpHgroundwater,increaseduptakecapacityofamendedsoil,andlong-termstabilityofthesequesteredHg.Long-termeffectivenesswastestedbysubjectingtreatedHg-loadedsoilstoleachingunderbothaerobicandanaerobicconditions.Overall,ferroussulfateandGACwerefoundtobethemosteffectiveamendmentsforremediationofsitegroundwater,whileaPortlandcement-ferroussulfatemixturewasthepreferredamendmentforminimizingleachingfromsitesoils28,70,71,72.

Basedonthebench-scaletestingresults,full-scaleimplementationinthenearfutureisanticipatedtoincludeacombinationofapproachesincludinginsituinjection/soilmixingandreactivebarrierstoaddressHgingroundwaterandsoilacrossthesite.

CASE STUDY 5: PULP AND TISSUE MILL, WASHINGTON STATE, USA



5.4 THERMAL TREATMENTMercury’schemicalproperties(seeTable4below)allowtheapplicationofvariousthermaltechnologiesfortheeffectivetreatmentofHg-impactedsoilandothersolidwastes.Experienceoverthelastdecadehasshownthatthermaltreatmentisoftenthemostcost-effectivemethodforremovingHgfromsolidwaste,especiallyforfine-grainedmaterialssuchassiltyandloamysoils.Commonco-contaminants,suchasPAHs,PCBs,dioxins,furans,TPHandorgano-leadcompounds, canalsobeeffectivelyremovedand/ordestroyedwithinproperlydesignedthermaltreatmentunits.

Table 4. Chemical Properties of Hg

Melting Point -38.8°C

Boiling Point 357.1°C(225°Cat50mbar)

VapourPressure 0.00163mbarat20°C

Anumberofex-situthermaltechnologieshavebeendevelopedandtestedinrecentyearsforthetreatmentofHg-containingsolidwastes,withvaryinglevelsofsuccess:

Heatedscrewconveyors/continuousmixers; Vacuumretorts; Vacuumthermaldesorption(indirectlyheatedbatchvacuummixers);and

Rotarykilns(direct-firedorindirectly heated).

Thelasttwotechnologies(vacuumthermaldesorptionandrotarykilns)havebeenproveneffectiveandeconomicallyviableforthetreatmentofHg-containingsoiland

solidwaste.Thermaldesorptionisalsobeingdevelopedfortheremediationofimpactedsoilsin-situ,withrecentstudiesindicatingsuccessfultreatmentofbothin-situsoiland biopiles.

Ex-situ Thermal Treatment - Vacuum Thermal Desorption (Batch Vacuum Mixers) Atthecoreofthebatchvacuummixerisanevaporationchamber,whichusesheatandacontrolledvacuumtovolatilisecontaminantswithboilingpointsbelow450°C(atatmosphericpressure).Thesystemistypicallyheatedbycirculatingsyntheticthermaloilinanexternalheatingjacketandthrougharotatingcentralshaft,whichalsomixesthewasteduringtreatment(Figure2).

Thetreatmentprocessisconductedinstagestoallowentrainedwaterandtargetcontaminantstoberecoveredseparately.Intheinitialstage,operatingtemperaturesofc.150°Candalowvacuum(c.800mbarabsolute)areappliedforwaterremoval.Followingevacuationofthewatervapour,

Batch vacuum mixer with solidification unit for treated material.Source: ECON Industries GmbH


theoperatingtemperatureisincreasedtoc.370°Candthepressureloweredtoc.50mbar(absolute)fortheremovalofHgandotherco-contaminants.

Theresultingvapourstreamisfilteredtoremoveentrainedparticulates,andthenrunthroughacondensingunitforcontaminantrecovery(Figure2).Thesubsequentexhaustgasstreamispassedthroughasecondaryvacuumunitandanactivatedcarbonfilterbeforedischargetotheatmosphere.Thetreatedsolidsaredischarged(hot)viaadischargeflapintoacoolingbunker,andsubsequenttreatmentbatchesareinitiatedwhilethepriorbatchcools.

Figure 3. Batch Vacuum Mixer Products

Treatedsoil inside evaporator chamber

Recovered mercury

Recovered hydrocar-bons

Recovered water


Feeding Unit

Input Material Vapour Filter

Condensation Unit

CondensorCoolingUnit

Vacuum Pump

Off-gas Cleanining

Discharge Bunker

Cooling UnitCoolingScrew

Discharger Unit

Thermal Oil Heating Unit

VacuDry® 6,000Evaporator

Clean Solids

Chiller

CondensateWater Mercury / Oil

ActivatedCarbon filter

Clean off-gas

Feding Pump

Source: ECON Industries. See process animation @ www.youtube.com/watch?v=3i_jxWDX2sY

Source: ECON Industries GmbH

Figure 2. Typical Batch Vacuum Mixer Process (Indirectly Heated)

Ex-situ Thermal Treatment - Rotary Kilns Rotarykilnsprovidecontinuoustreatmentunderminimalvacuum(Figure4).Thewastematerialiscontinuouslyfedandconveyedthroughtherotatingkilnbyascrewconveyor,whereitisheatedtothedesiredtreatmenttemperature(typically650to1,100°C).Additionalmixingbladescanbeinstalledinthekilntoenhancemixingandincreaseretentiontime.Thetreatedmaterialdropsoutoftherotarykilnandiscooledonacoolingconveyorbeforedischarge.

Theoff-gasisfirstdirectedthroughacycloneforparticulateremoval,andthenprocessedinanafter-burnerchamberwhereitisexposedtooxidizingconditionsat850°Cforapproximately4secondstoavoidformationoftoxicsubstances(e.g.dioxins).Followingtreatment,thewaterandHgintheoff-gasiscondensed,andtheoff-gasisthenscrubbedandfilteredbeforebeingtreatedbyactivatedcarbonanddischargedtotheatmosphere.

Direct-firedrotarykilnunitsareequippedwitharefractoryliningoralayerofheat-resistantconcreteandthewastematerialisheateddirectlybyafront-mountedburner.Althoughrarelyused,theindirectly-heatedrotarykilnstypicallyconsistofasteelcylinderwithoutaninnerrefractorylining.Inthiscase,thekilnisindirectlyheatedbythehotexhaustgasesfromagasburner.

Source: ECON Industries GmbH

Figure 4. Direct-fired Rotary Kiln including Off-Gas Treatment

http://www.youtube.com/watch?v=3i_jxWDX2sY



Ex-situ Thermal Technology ComparisonAcomparisonofthebatchvacuummixerandrotarykilntechnologiesisprovidedinTable5.Duetotheloweroperatingtemperatures,theindirectly-heatedbatchvacuummixeristypicallyusedwhennocinnabar(HgS)orHg(I/II)chlorideispresentinthewastematerialtobetreated,including:

Excavatedsoilsanddemolitionwastefromindustrial sites;

Sedimentsfromlakesandstreams;and Sludgefromgasexplorationandproduction.

Therearenolimitationswithrespecttothewatercontent,orconcentrationsofhydrocarbonsorHgfortreatmentinabatchvacuummixer.Theprocessisaclosedsystem,andsocanusuallybepermittedforuseinsensitiveareas.

Incomparison,therotarykilntechnologycanbeappliedtowastecontainingallHgspecies,includingHgSandHg(I/II)chloride,andhasbeenusedtotreatthefollowingwaste streams:

Catalystsfrompetro-chemicalprocesses; Disposedactivatedcarbon; Sometypesofimpactedsoil(e.gvinylchlorideproductionsites);and

HgS-richsludgesfromindustrialwastewatertreatmentprocesses.

Therotarykilnprocessisgenerallymoreenergy-intensivethanbatchvacuummixers,andisthereforelesseconomicalformaterialswithelevatedwatercontent.Wasteswithhydrocarboncontentgreaterthan5%cancauseoverheatingofthekiln.

Rotarykilnstypicallyproducemoreairemissionsthanbatchvacuummixers,requiresophisticatedoff-gastreatmentsystemsandmonitoring,andcanbedifficulttopermitforusewithinsensitiveareas.Theprocesscanalsoproducesignificantquantitiesofwastewater(c.0.5-1.0TofwastewaterperToftreatedwaste)duetotheneedforoff-gas scrubbing.

Batch Vacuum Mixer (Indirect Heating)

Rotary Kiln (Direct Fired)

Typical Application

ElementalMercury ✓ ✓

MethylMercury ✓ ✓

Mercury(I/II)Chloride X ✓

MercurySulphide/Cinnabar(HgS) X ✓

Hydrocarbons (NoLimit) (Upto5%Max)

PAHs,TPH,PCBs,Dioxins,Furans,Organo-lead ✓ ✓

Elevated Water Content NoLimit Upto25%(Max)

Elevated Mercury Content NoLimit NoLimit

Wastecharacteristics Sludge,soil,filtercakes,includingpoorly-conveyableandhighly-viscousmaterials Sludgeandsoil(upto25%moisture)

Mobileinstallationforon-sitetreatment ✓ (withappropriateairemissionscontrols)

Typicalplantthroughputcapacities 10 000-50 000T/annum 30 000-50 000T/annum

Treatment Efficiencies and Other Considerations

Hglevelsaftertreatment <1ppm <1ppm

TypicalMaxProcessTemperatures Upto370°C 650°Cto1,150°C

Off-gasStream 100–1000Nm3/hr 5000–25000Nm3/hr

Distillates Distillatescanberecoveredseparately(nocombustion) Mercury is recovered

Off-gastreatment Vapourfilter,two-stagecondensationunit,andactivatedcarbonfilter

Cyclone,post-combustionchamber,gas-scrubber,e-filter,andactivecarbonfilter

Airemissions MinimalTypically>batchvacuummixer.Requiressophisticatedoff-gastreatmentsystemandmonitoring

Additionalproducedwastewater None ~0.5-1TwastewaterperTmaterialtreated(fromoff-gasscrubbing)

Approx.Energyconsumptionpertonsoiltreated(sandy;15%moisture) ~210kWh/t ~700kWh/t

Safety Operationundervacuum(50mbarabsolute),inertatmosphere

Limitedvacuum(3mbardifferential),oxidizingatmosphere

EnvironmentalpermittingStateofthearttechnology,permittingoftenpossibleinsensitiveareas(closedsystem)

Stateofthearttechnology,permittingcanbedifficultinsensitiveareas

Table 5. Comparison of Ex-situ Thermal Treatment Methods


In-situ Thermal DesorptionInrecentyears,thermaldesorptionhasbeendevelopedandisbeingappliedtoin-situremediationofimpactedsoilsandbiopiles.Asfortheex-situtreatmentmethodsdescribedabove,thetemperatureoftheimpactedsoilisraisedusinganetworkofheatingtubestoachievetheappropriatetemperature,pressure,andresidencetimeforcontaminantdesorptionfromthesoilmatrix.Thetubesaretypicallyheatedthroughthecirculationofhigh-temperaturecombustiongasesinaclosedloop(Figure5).Themobilecombustionburnersaretypicallyrunoneitherpropaneornaturalgas.

Comparedtoconventionalex-situthermaldesorptiontechnologies(e.g.rotarykilns,batchvacuummixers),wherethesoilresidence

timesaretypicallyaround20minutes,theheatingtimeforthein-situprocesstakesmuchlonger(e.g.severalweeks).However,thetreatment“batches”canbesubstantiallyhigher,allowingpotentiallysimilarmonthlytreatmentcapacities.

In-situthermaldesorptionisanemergingtechnologyforthemanagementofHgimpactedsites.Inthisapplication,desorbedHg(andothervolatileco-contaminants)arecollectedwithincollectionpipesundernegativepressureandcondensed/recovered.Exhaustgastreatmentisoftenrequired(e.g.sulphur-enrichedactivatedcarbon).However,oneconcernassociatedwithin-situthermaltreatmentisthepotentialforun-controlledcondensationofelementalHginareasofrelativelylowertemperature..


Figure 5. Schematic of In-situ Thermal Remediation Unit

FanActivated carbon(impregnated)

Liquid Hg

Aspiration tubes (perforated) Heating tubes (not perforated)

Water 3 C

Source: TPS Tech

INDUSTRIAL SITE SINCE 1918, INCLUDING THE PRODUCTION OF LIGHT ISOTOPES THROUGH LITHIUM‑MERCURY AMALGAM ISOTOPE SEPARATION (1960‑2009). ON‑GOING EXCAVATION AND TREATMENT OF C. 70,000 T OF HG‑IMPACTED SOIL AND BUILDING RUBBLE CONTAINING HYDROCARBONS, WITH HG CONCENTRATIONS RANGING TO > 2,600 MG/KG AND LEACHATE TEST RESULTS OF UP TO 1.3 MG/L MERCURY. THE SITE IS CLOSE TO RESIDENTIAL HOUSING AND POTENTIAL AIR EMISSIONS ARE OF CONCERN TO THE LOCAL COMMUNITY.

Key learnings Acombinationofcrushing,soil-washing,vacuumthermaldesorptionandstabilizationwasutilisedtoachievecost-effective treatment.

Coarsermaterial(30mm>80mmdiameter)treatedthroughsoilwashing.

Finermaterial(<30mm)treatedinavacuumthermaldesorptionunit.

Gradualheatinginthevacuumthermaldes-orptionunitallowsrecoveryofhigh-purityHg.

TheclosedvacuumsystemensuresHgemissionsarewellbelowregulatorylimits.

Stabilizationoftreatedmaterialsrequiredforseveralco-contaminants,includingAs,Cd,andothermetals.

Afterstabilization,thetreatedmaterialisre-usedonsite.

Keyprojectanddesigncharacteristics: Projectduration:2010–2015(planned). Hgcontentoftreatedmaterial:from0.1–1

mg/kgwithleachtestresults< 0.01 mg/l. Treatmentbatchsize:8.4m3. Heatingsystem:1,800kW/400°Cthermal

oilunitheatedbynaturalgas. Operatingpressures:10to800mbar

(absolute).

Excavation

Crushing

Crushing

Finematerial Soil scrubbing

Coarse materialVacuum thermal

desorption

Stabilization QualityControl

Cleanedsoil

Cleanedsoil

Finalqualitycontrol

PureMercury

Screening < 30 mm 30 mm - 80 mm

Hg contentexceeds legal

limits

Hg contentmeets legal

limits

Wastewater

treatment

Wastewater

treatment

Wastewater

Wastewater

CASE STUDY 6: MIRAMAS INDUSTRIAL SITE, SOUTHERN FRANCE


SITE OPERATIONS DATING BACK TO THE LATE 19TH CENTURY INCLUDED THE ELECTROLYSIS OF SODIUM CHLORIDE SOLUTIONS USING HG ELECTRODES, AND THE SYNTHESIS OF AMINO‑ANTHRAQUINONE USING AN HG‑BASED CATALYST. A SITE ASSESSMENT, CONDUCTED FOLLOWING THE ESTABLISHMENT OF THE SWISS CONTAMINATED SITE ORDINANCE IN 1998, IDENTIFIED AN AREA IN THE VICINITY OF A FORMER WASTE WATER SETTLING POND AS A HIGH PRIORITY FOR FURTHER INVESTIGATION. THE SETTLING POND WAS BUILT IN 1932, AND UNTIL 1972, COLLECTED WASTE WATER FROM THE PRODUCTION FACILITY AND COMMUNITY PRIOR TO DISCHARGE INTO A NEARBY RIVER. SUBSEQUENT INVESTIGATIONS AND RISK ASSESSMENT IDENTIFIED POSSIBLE RISKS TO ENVIRONMENTAL RECEPTORS UTILISING THE HEAVILY‑VEGETATED POND (E.G., AMPHIBIANS, DUCKS, SWANS AND OTHER BIRDS.) THE SELECTED REMEDIAL ACTION INCLUDED SLUDGE/SEDIMENT REMOVAL FROM THE POND BOTTOM FOLLOWED BY EXCAVATION OF UNSATURATED SOILS BENEATH THE POND.

Key learnings TotalHgconcentrationsofupto200mg/kgweremeasuredinthepondsediments/sludge,withisolatedhotspotsupto700mg/kgHg.DuetothelowconcentrationsofHginsitegroundwater(<1µg/L),laboratoryHgspeciationanalyseswerenotconducted.

Potentialrisksassociatedwithgroundwaterdown-gradientofthepondwererelatedtoorganicco-contaminantsandnotHg.

Thesitecharacterisation(grid-basedsampling)showedsignificantvariabilityinthehorizontalandverticaldistributionofHgwithinthepond.Thehighestconcentrationswerefoundwithinpondsediments/sludgeandatthebaseofthedamsupportingthe pond.

Arisk-basedremediationtargetvalueof<20mg/kgtotalHgwasinitiallyestablishedforthesite,withtheacceptancethatcomplete

decontaminationofthesitewouldnotbepossible,andthatthesitewouldremainintheCantonregistryofcontaminatedsites.

Down-gradienthydrauliccontainmentwasimplementedduringtheremovalactionasaprecautionarymeasure.However,Hgissueswerenotidentifiedingroundwaterduringoraftertheremediation.

Avacuumextractiontechniqueappliedunderwetconditionswasselectedforthepondsediment/sludgeratherthandryexcavationunderatent.Thistechniquehadtheadvantageofavoidingdustgenerationandsignificantairemissionsduringsludge removal.

Theextractedsludgewasdewateredthroughanextruderandthepressedsoilcake(maxconcentrationof150mg/kgHg)transportedtoGermanyforthermaldesorptionorincineration,basedontheHgconcentrations.

CASE STUDY 7: WASTE-WATER SETTLING POND, SWITZERLAND

Hgconcentrationsinthegeneratedfiltrate(30m3/hr)werebelowapplicablecriteriafordischargetothemunicipalsewagetreatment plant.

Afterremovalofthepondsludgeandsediment,itbecameapparentthatprevioussludgeremovalactivitiesconductedinthe1970’shadlikelydisturbedthelowpermeabilitylayerbeneaththepondandresultedinHgmigrationdeeperintosoilsbeneaththepond.Thispromptedfurthersoilexcavationdowntotheaveragegroundwaterlevel.TheadditionalremediationstepresultedinanaveragetotalHgconcentrationof<5mg/kg,whichwastherevisedthresholdvalueafterthisremediationphase.

Source: NICOLE member

Source: NICOLE member


5.5 OTHER SOIL TREATMENT TECHNOLOGIES UNDER DEVELOPMENT

AnumberofotherHgremediationtechnologiesareemergingforsoils,althoughtodatethesehavehadlimitedcommercialapplicationorhavenotprogressedbeyondpilotstage.Somehavesignificanttechnicalhurdlestoovercomepriortobeingreadilyavailabletechnologies.Theseinclude:

In-situelectro-remediation; Bio-treatment(Fixed-BedBioreactors);and Phyto-extraction.

In-Situ Electro-RemediationElectro-remediationinvolvestheapplicationofalow-intensitydirectcurrentacrosselectrodestodrivemigrationofchargedmoleculestotheoppositesignelectrode.Electro-remediationisonlyeffectiveonmobilecontaminants.InmostHg-impactedsoils,Hgisnotmobileenoughforthetechnologytobeeffectivewithouttheuseofamobilisingagent.Promisingresultswereshownatbench-scaleusinganiodine/iodidemobilisingsolution.Apilottestwasbuilttoevaluatethetechnologyforthetreatmentoftheunsaturatedzone.Atthestart,theelectro-osmoticflowthatdevelopedatthecathodewashigherthanexpected,hencecreatingariskofuncontrolledmigrationofmobilisingsolution.Asaresult,allpartnersinthisproject(technologyprovider,industrialoperator,regulatoryauthority)decidedtostopthepilottest.Thecontrolofthiselectro-osmoticflowisamajorchallengetobesolvedforthis technology.

Bio-Treatment (Fixed-Bed Bioreactors)Bio-treatmentcanbeachievedusingeitheranaerobicprocesswhichconvertssolubleionicHg(Hg2+)toelementalHg(Hg0)forextraction/recovery,oracombinedaerobic/anaerobicmethodwhichconvertssolubleionicHgtoinsolublemineralphases.Inbothapproaches,proprietarymicrobialculturesareused,andtheeffluentproducedtypicallyrequiresfurther treatment.

Phyto-ExtractionPhyto-extractioninvolvesplantseithernaturallytakingupchemicalsintotheirbiomass,orthesameeffectbeingchemicallyinducedbymobilisingagents.Noplantshaveyetbeenidentifiedwhichnaturallyhyper-accumulateHg,althoughevidenceexistsofelementalHguptakefromambientairbyplantleaves.Chelatingagents(suchasthiosulfate)havebeenshowntomateriallyincreaseHgmobilisationinsoilsolution,hencetoincrease

Concentrated flow of Hgl4

2-

I2- , I-

cathode - anode +

Hgl42-I3

- , I-

HgHgl4

2- , IO3-

Regeneration unit

+-


Principle (patented EP 1 090 695 A1)

Figure 6. In-Situ Electro-Remediation Schematic uptakebyplants.Phyto-extractionislimitedtotherootzoneoftheparticularplantbeingusedandoff-sitedisposalofHg-impactedbiomassisamajorcostthatneedstobefactoredintothedesign.ThepotentialforHgleachingbelowtheplantrootzoneandthepotentialofbacterialreductionofionicHgtoelementalHgintherootzoneneedtobeconsideredwhencontemplatingphyto-extractionasasitemanagementsolution.

5.6 TECHNIQUES TO ADDRESS GROUNDWATER

DevelopingarobustCSM,byunderstandingtheambientandanthropogenicgeochemistry,hydrogeologicalregimeandcurrent/futureHgspeciation,isstronglyadvisedpriortocommittingtoimplementationofgroundwaterremediation.WhereremedialsystemshavebeenimplementedtomanageHg-impactedgroundwater,proventechnologiesinclude:

HydraulicContainment; PumpandTreat; Interceptionandamendment,permeable

reactive barriers; Interceptionandcapture,in-groundcarbonwalls(orotherabsorbents)infunnelandgatesystems;and

Containmentusingengineeredin-ground barriers.

Forhydrauliccontainment,pumpandtreat(viacarbonabsorption)andcontainmentusingengineeredin-groundbarriers,thetechnologiesarewellprovenandmuchliteratureispresentdescribingthemeritsofeachapproach.

ThisbookletisfocussedondescribingoptionsthatprovideavarietyofapproacheswhichhaveaparticularapplicationwithregardtoHg,suchastheuseoftechnologiesdesignedtoamendplumechemistryandcaptureHg70,71,72.

Mobilization of Hg from land to groundwater and biological transformation along flow paths in an unconsolidated sandy, acidic aquifer. (Source: Occurrence and Mobility of Mercury in Groundwater73. http://dx.doi.org/10.5772/55487)

http://dx.doi.org/10.5772/55487


FOLLOWING CESSATION OF OPERATIONS AND HOT SPOT REMOVAL (50 MG/KG SOIL TARGET), A FUNNEL AND GATE SYSTEM WAS CONSTRUCTED AT A CHLOR‑ALKALI PLANT IN AUSTRIA. THE GATE WAS A MIXTURE OF GRAVEL AND ACTIVATED CARBON DESIGNED TO HAVE A LIFE‑SPAN OF SEVERAL YEARS. THE RESIDUAL GROUNDWATER PLUME IS FUNNELLED TOWARDS AN ACTIVATED CARBON BOX IN THE GATE, AND HG IS REMOVED AS GROUNDWATER PASSES THROUGH. THE MAXIMUM LOADING WAS ESTIMATED AT 6 G/D HG FROM A RESIDUAL PLUME OF UP TO 50 µG/L. A SENSITIVE RECEPTOR IS LOCATED 350 M DOWN‑GRADIENT OF THE SITE AND LONG‑TERM MONITORING RESULTS SHOWED A STABILIZATION OF HG LEVELS DOWN‑GRADIENT OF THE GATE BELOW THE 1µG/L TARGET.

Key learnings Thesystemwasbuiltintwosteps,withthefunnelbeingbuiltin2001.Thiswasinitiallyoperatedbycontinuouslypumpingat12.5m³/hfortwoyears.Thisperiodwasusetodefinethebestmaterialforthegate.

Thevibratingbeammethodwasusedtoinstalltheverticalbarrier(funnel).Abeamwasvibrateddowntothedeepestpointand

thengroutinjectedintothevoidcreatedwhilewithdrawingthebeam.Thefinalfunnelcharacteristicsare:

Totallength 245m Depth 22-24m-bgs Thickness 0.06m Barrierstartsat 0.6m-bgs Barrierendsat 2minthefinesands Permeability 1x10-8m/s

Source: Solvay SA

CASE STUDY 8: FUNNEL AND GATE, AUSTRIA

Apermanentgatewasthenbuiltin2004byexcavating9overlappingcylindersthroughthewalldowntoadepthof15.5m-bgs.Eachcolumnwasthenbackfilledwithamixtureofactivatedcarbonandgravelfromthebasetoupto5.5m-bgs(i.e.0.5mabovemeangroundwatertable).

Renewalofthegatewillbeachievedbyexcavatingthespentactivatedcarbonandrefillingwithnewcarbononcethecapacityhasbeenreached.Thefinalgatecharacteristicsare:

Permeablegatevolume 150m³ Waterresidencetime 205minutes Activatedcarbon 100m³(53T) Gravel 50m³(98T)


5.7 OTHER GROUNDWATER TREATMENT TECHNOLOGIES UNDER DEVELOPMENT

Thereison-goingefforttodevelopeffectivetreatmentprocessesfordissolvedHgingroundwater.Currentprocessesincludeabsorptivesystemsandreactivesystems.Absorbentsystemsincludeconventionalactivatedcarbontechnologies.However,otherabsorbentsarealsobeingdevelopedandofferpotentialadvantagesincertaincircumstances.Absorbentsmaybebasedonnaturalproducts(e.g.,immobilisedalgae,biochar)ormaybesyntheticchemicals(e.g.,chelatingagents,nanotechnologies).Reactivesystemsincludetechnologiessuchaschemicalreductionandstrippingandtheuseofcopperorbrass shavings.

Immobilised AlgaeBio-RecoverySystemsInc.recentlyconductedaprojectaspartoftheUSEPA’sSuperfundInnovativeTechnologyEvaluation(SITE)ProgramtoevaluatetheabilityofimmobilisedalgaetoadsorbHgfromimpactedgroundwaterinlaboratorystudiesandpilot-scalefieldtests.Thealgalbiomasswasincorporatedinapermeablepolymericmatrixwithinthetreatmentunit.

Theproduct,AlgaSORB©,whichwaspackedintoadsorptioncolumnsmadeupofpermeablepolymericmatrix,reportedlyexhibitedexcellentflowcharacteristics,andfunctionedasa“biological”ionexchangeresin.Likeion-exchangeresins,AlgaSORB©canberegenerated.Asequenceofelevenlaboratorytestsdemonstratedtheabilityofthisproduct

toadsorbHgfromgroundwaterthatcontainedhighlevelsoftotaldissolvedsolidsandhardwatercharacteristics.However,useofasingleAlgaSORB©preparationyieldednon-repeatableresultswithsamplescollectedatdifferenttimesoftheyear54.

ThestrategyofsequentiallyextractingtheHgfromgroundwaterthroughtwocolumnscontainingdifferentpreparationsofAlgaSORB©wasdevelopedandprovedsuccessfulinlaboratoryandpilot-scalefieldtests.FieldtestresultsindicatethatAlgaSORBcouldbeeconomicallycompetitivewithionexchangeresinsforremovalofHg,withtheadvantagethathardnessandotherdissolvedsolidsdonotappeartocompetewithheavymetalsforbindingcapacity54,55.

BiocharAstudyconductedin2013atUMBCevaluatedarangeofbiocharsmadefromanumberofagriculturalresidues,phragmites(beneficialuseofinvasivespeciesinwetlands),and


Portable Effluent Treatment Equipment using AlgaSORB©. Source: www.clu-in.org

hardwoods.Inaddition,someofthebiocharswereactivatedeitherphysicallyorchemicallytoenhancetheirsorptiveproperties.SomeofthebiocharswereimpregnatedwithironoxidestoevaluatetheenhancementofsorptionofHgandmethyl-Hg.

Thestudyshowedthatbiocharswereabletosorborganiccontaminants,Hgandmethyl-Hg,makingthemattractivealternativestoactivatedcarbonforsitesimpactedwithbothorganicandinorganiccontaminants.Activatedcarbonproductshavealimitedamountofsorptionsitesavailableforinorganiccontaminantsrelativetobiochars,andtheirperformancetypicallydropswithincreasingHgconcentrations.Thebiochars,particularlythosederivedfrompoultrylitter,wereabletoremovemoreHgfromsolutionathigherHgconcentrationscomparedtoothercarbons(>99%Hgremovalinastudy).ItispossiblethatthehighphosphatecontentofthesepoultrylitterbiocharsisresponsiblefortheenhancedHgsorption57.

Inonelaboratory-scalestudyofHg-impactedsediments,40differentsubstrateswerecharredtogetthemostoptimalcharacteristicsforabsorbingHg.Ofthese,abiocharcalled“CowboyCharcoal”,madefromRedOakfromKentucky,wasnarroweddownasthebest.Mercurywaspresentinthesedimentasinsolublesulfides(metacinnabar)andalsoinsolubleforms.The“CowboyCharcoal”wasabletoremoveconsiderableamountsofHgfromthewaterphase/sedimentporewater.Adsorption/absorptionsitesremainedavailableaftertreatment(thecapacitywas

notfullyutilized),andthebiocharretainedtheadsorbedHgbetterthanGAC(SediMite)58.Basedontheresultsofthelaboratorytesting,furtherpilottestingisplanned.

MoreinformationregardingBiocharcanbefoundathttp://www.biochar-international.org.

Use of Chelating AgentsChelatingresinsarecommerciallyavailableandusedfortheremovaloflow-levelsofHgandsolubleHgsaltsfromwastewaterssuchasbrineandotherindustrialeffluents,includingfromchlor-alkaliprocessingfacilities.Followingtreatment,theHgisstronglyboundtotheresin’sfunctionalgroupstoformstablecomplexes.Thesepropertiesarereportedlylargelyunaffectedbyhighchlorideorsulphatecontentinthewatertreated.Effluentsolutionscontaining2-20mg/lHgcanbetreatedusingresinssuchasPurolite®S-920toreducetheconcentrationinsolutiontolessthan0.005ppm59.Otherchelatingagents,suchasEvonikIndustriesTMT15®arealsocommonlyusedtoremoveheavymetalssuchasHgfromindustrialwastewaters,suchasgasscrubberwatersandotherprocesswaters60.

Apilotstudyhasbeenundertaken61 to examinetheremovaloflow-levelsofHgfromgroundwaternearachlor-alkaliplantusingasyntheticchelatingligand.Onecommercially-availablecompoundwasfoundtobecapableofreducingHgconcentrationstobelowdetectionlimits(0.05μg/l),withtheaddedbenefitofproducingastableprecipitate.


NanotechnologyNanotechnology(ThiolSAMMS),developedbyPacificNorthwestNationalLaboratory,comprisesnano-porousceramicsubstrate withahighsurfaceareawithlayersofadsorptiveplateswithselectiveaffinityforHg.TestingshowsHgloadingashighas635mg/landsequentialtreatmentyieldedeffluent <0.1mg/l62.

Chemical Reduction and StrippingFieldandlaboratorytestshaveconfirmedtheuseofchemicalreductionandairstrippingfortreatmentofwatercontainingHg2+.Theprocessconsistsofdosingthewaterwithlowlevelsofstannouschloride(tin2+chloride)toreducetheHgtoelementalHg(Hg0).TheHg0canthenberemovedfromthewaterbyairstripping.Reagentdoses,withSntoHgratiosgreaterthanabout5to25,showednearlycompleteremoval(~94%)andyieldedfinalHgconcentrationsof<0.01µg/L.Thepurgeaircanbetreatedwithactivatedcarbonas needed63.

Use of Copper or Brass ShavingsTheuseofcoppershavingstoremoveHgfromimpactedgroundwaterbyamalgamationhasbeeninvestigatedatanexperimentallevel.Batchsorptionexperimentsshowedthat96-98%ofHg2+wasremovedwithin2hours.ColumnexperimentswerealsoperformedwithanHgsolution,whichshowedthatnoHgbreakthrough(>0.5ug/l)couldbedetectedaftermorethan2,300percolatedporevolumes.Copperwasreleasedfromtheshavingsduetotheamalgamationprocessandduetocoppercorrosionbyoxidation,resultinginconcentrationsofmobilisedcopperof0.2−0.6mg/l.TheauthorssuggestthatgiventheefficientremovalofHg2+fromaqueoussolutions,thatcoppershavingscouldbeemployedinasequentialsystemofHgamalgamationfollowedbyremovalofmobilisedcopperusinganionexchanger(e.g. zeolites).

Brass(copper-zincalloy)isbeingusedinsituatpilotscaleataformerwoodtreatmentfacilityinordertotreatanHgplumeby amalgamation65.


NICOLE PUTS FORWARD THE FOLLOWING BEST PRACTICE RECOMMENDATIONS, FIRSTLY FOR CHARACTERISATION AND RISK ASSESSMENT, AND THEN SITE MANAGEMENT.

BEST PRACTICE RECOMMENDATIONS6

1.Keepthoroughhistoricalrecordsofindustrialprocessandbuildingstructures,includinginfrastructure(foundations,networks).ThesearekeyelementsoftheConceptualSiteModel(CSM)andhelptofocuscharacterisation.

2.SufficientcharacterisationisneededtobuildarobustCSM,setadequatereserves,negotiatetherightclean-upgoalsandcontrolprojectcosts.

3. Selectinvestigation/samplingtechniquesthatavoidHgmigrationandobtainrepresentativedata.Allowforfull-timesupervisionbytrainedandexperiencedsiteengineers.

4.UnderstandHgspeciationandambient/anthropogenicgeochemistry,toquantifycurrentandfutureHgmobility/toxicityandpotentialrisks.

5.Bewareof“nuggeteffects”:useon-sitemeasurements,increasesamplingfrequency,usestatisticalmethods(e.g.95%UCL)forriskquantification.

6. Usedirectmeasurementwhereverpossible(vs.relyingonmodelling)tocharacteriseexposuremediaandmigrationpathways,soastobestquantifypotentialrisks.

7.Makesurepotentialco-contaminationisunderstood(e.g.dioxins,CVOCs).

8.ProactivemanagementofHealth&Safetyrisksneededduringcharacterisation.

NICOLE BEST PRACTICE RECOMMENDATIONSCHARACTERISATION AND RISK ASSESSMENT


TWO KEY RESEARCH AREAS HIGHLIGHTED FOR CONSIDERATION: 1.Experimentalwork(laboratory,field)onthephysic-chemicalbehaviourofHgintheenvironment,soastovalidatepredictivemodels;and

2.Longtermefficiencyofin-situstabilisation/solidification,includingimplementationoflong-termmonitoringprogrammes.

1.Themanagementstrategyshouldbalanceremediationwithothermanagementmeasures(e.g.deedrestrictions)tomitigaterisksandreducelong-termliability.

2.Negotiateappropriateandachievableclean-upgoals.Theseshouldberisk-based,respectsustainableremediationprinciplesanddeliverNetEnvironmentalBenefit.

3.Donotdefineclean-upthresholdsforTotalHg,asthesetendtobeoverlyconservative.Instead,focusonmitigatingHgspeciesdrivingriskand/oramassremovalapproach.

4.SelecttherightremediationtechniquefortheConceptualSiteModel,ifneedsbefollowingappropriatefeasibilitytesting(e.g.lab-scaletests,pilottrials).

5.Usequalifiedandexperiencedserviceproviders(consultants,contractors).

6.Duringexcavationandothergrounddisturbance,implementoversightbyqualifiedpersonneltooptimisesoilvolumesandminimisetheriskofdownwardHgmigration.

7.Giventhehighcostsofoff-sitedisposal,optimisesoilvolumes(e.g.carefulsegregationduringexcavation,sorting,washing).

8.Stringenthealthandsafetymanagementduringremediation,includingbiologicalandair monitoring.

NICOLE BEST PRACTICE RECOMMENDATIONSREMEDIATION AND OTHER MANAGEMENT MEASURES

ENDNOTES

1 Remediation of mercury contaminated sites – a review, Jianxy Wang et al, Journal of hazardous materials 221-222 (2012) 1-18.

2 The UNEP Minamata Convention on Mercury. http://mercuryconvention.org/

3 http://eippcb.jrc.ec.europa.eu/reference/cak.html

4 COMMISSION IMPLEMENTING DECISION of 9 December 2013 establishing the best available techniques (BAT) conclusions, under Directive 2010/75/EU of the European Parliament and of the Council on industrial emissions, for the production of chlor-alkali (notified under document C(2013) 8589) (2013/732/EU). http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=OJ:L:2013:332:0034:0048:EN:PDF

5 Regulation (EC) No 1102/2008 of the European Parliament and of the Council of 22 October 2008 on the banning of exports of metallic mercury and certain mercury compounds and mixtures and the safe storage of metallic mercury.

6 COUNCIL DIRECTIVE 2011/97/EU of 5 December 2011 amending Directive 1999/31/EC as regards specific criteria for the storage of metallic mercury considered as waste.

7 http://www.commonforum.eu/Documents/DOC/Clarinet/clarinet_nicole_jointstatement.pdf

8 http://www.nicole.org/uploadedfiles/wg-sustainableremediation-finalreport.pdf

9 Nicole – Mercury Technical Workshop http://www.nicole.org/uploadedfiles/nicole-brussels-december2012.pdf

10 Murphy R. 2012. Mercury Contaminated Site Management - US Experience - ARCADIS, NICOLE Mercury Working Group Meeting, June 2012, Baden-Baden.Germany.

11 The biogeochemical cycling of elemental mercury: Anthropogenic influence, RP Mason Geochimica et Cosmochimica Acta, Vol. 58,No.15,pp. 3191-31981, 1994.

12 Elemental Mercury and Inorganic Mercury Compounds: Human Health Aspects. Concise International Chemical Assessment Document 50.World Health Organization. Geneva, 2003. http://www.who.int/ipcs/publications/cicad/en/cicad50.pdf


13 Foster, TJ, 1987. The genetics and biochemistry of mercury resistance, Critical Review Microbiology 1987, 15: 117-140.

14 R.S. Oremland et al. 1991. Methylmercury decomposition in sediments and bacterial cultures: involvement of methanogens and sulfate reducers in oxidative demethylation. Applied Environmental Microbiology. 57 (1) : 130-137.

15 Brooks Applied Labs SOP #BR-0013, 5-Step Selective Sequential Extraction Procedure for Mercury Speciation in Solids. http://www.brooksrand.com/

16 Mercury transport and transformation at the Black Butte Mine Superfund Site, Eckley, CS (USEPA

Region 10), Luxton, T (USEPA EPA ORD National Risk Management Research Lab), Schenk, L (USGS OWSC), McKernan, J (USEPA EPA ORD National Risk Management Research Lab), Goulet, J (USEPA Region 10), Lynch, K (USEPA Region 10), Muza, R (USEPA Region 10).

17 The SNOWMAN Network is a transnational group of research organizations in the field of Soil and Groundwater in Europe (www.snowmannetwork.com).

18 Enhanced Knowledge in Mercury Fate and Transport for Improved Management of Hg Soil Contamination. 1-10-2011 through 31-3-2014. http://www.snowmannetwork.com/main.asp?id=320

19 Leterme B., Blanc P., and Jacques, D.A. 2014. Reactive transport model for mercury fate in soil-application to different anthropogenic pollution sources. 30 May 2014.

20 Jason Cole, Ph.D., P.E.. 2012. High resolution passive soil gas sampling for Elemental Mercury Characterization (CH2MHill).

21 SNOWMAN NETWORK, Enhanced Knowledge in Mercury Fate and Transport for Improved Management of Hg Soil Contamination - Characterization of Mercury Contaminated Sites. 27 February 2014.

22 Dennis G. Jackson, Carol Eddy-Dilek, Brian B. Looney. Evaluation of Cone Penetrometer-Based Tools for the Characterization of Elemental Mercury. Savannah River National Laboratory (www.em.doe.gov).

23 http://www.brooksrand.com/

ENDNOTES

24 NICOLE, Report on the NICOLE Workshop: Sustainable Remediation – A Solution to an Unsustainable Past.

25 SuRF UK, A Framework for Assessing the Sustainability of Soil and Groundwater Remediation, March 2010.

26 Directive 2008/98/EC of the European Parliament and of the Council of 19 November 2008 on waste and repealing certain Directives.

27 EEA, Movements of waste across the EU’s internal and external borders, 2012.

28 USEPA. 2007. Treatment technologies for mercury in soil, waste, and water, USEPA, EPA-542-R-07-003. http://www.epa.gov/tio/download/remed/542r07003.pdf

29 Fysicochemische verwijdering van metallisch kwik uit de bodem, Bram De Smit, Master thesis, 2009, University of Ghent, Belgium.

30 Verwijdering van metallisch kwik uit bodem d.m.v. nat-extractieve reiniging, Evelien De Witte, Master thesis, 2011, Catholic University Ghent.

31 Feasibility study of soil washing to remediate mercury contaminated soil, Jingying Xu, Licenciate thesis, 2013, Luleå university of technology, Sweden.

32 Luther, SM, MJ Dendar, 1996. Remediation options for mercury contaminated soils at the Turner Valley gas plant. Department of renewable resources, University of Alberta, Canada.

33 Orica Botany Bay project. http://www.oricabotanytransformation.com/?page=119

34 Remediation of a former chloralkali plant in the Netherlands, Pensaert S., Gerbrands B., NICOLE technical meeting - Mercury contaminated sites, Brussels, Belgium, December 2012.

35 Verwijdering van metallisch kwik uit bodem door middel van ultrasoon, Luke Pistorius, Master thesis, 2014, University of Ghent, Belgium.

36 CL:AIRE Guidance Bulletin GB1, November 2005.

37 Environment Agency. Guidance on the use of Stabilisation/Solidification for the Treatment of Contaminated Soil. R&D Technical Report P5-064/TR/1.

ENDNOTES


38 Environment Agency. Model Procedures for the Management of Land Contamination. Contaminated Land Report (CLR) 11.

39 Hagemann, S. 2009. Technologies for the Stabilization of Elemental Mercury and Mercury-containing Wastes: Final Report. Volume 252. Gesellschaft für Anlagen- und Reaktorsicherheit (GRS).

40 Spence, R. MASS: Mercury Amalgamation Stabilization/Solidification. Oak Ridge National Laboratory. http://web.ornl.gov/~webworks/cppr/y2001/pres/114122.pdf

41 Ebadian, M.A. 2001. Mercury Contaminated Material Decontamination Methods: Investigation and Assessment. U.S. Department of Energy. Technical Report Number FG21-95EW55094-02.

42 Kalb, P.D., J.W. Adams, and L.W. Milian. 2001. Sulfur Polymer Stabilization/Solidification (SPSS) Treatment of Mixed-Waste Mercury Recovered from Environmental Restoration Activities at BNL. BNL-52614.

43 Hinton, J., Veiga, M. 2001. Mercury Contaminated Sites: A Review of Remedial Solutions, NIMD Forum 2001 - Mercury Research: Today and Tomorrow, Minamata City, Japan, National Institute for Minamata Disease, Ministry of the Environment, Japan, 73-84. http://www.facome.uqam.ca/pdf/Minamata_Forum_2001.PDF

44 Ebadian, M.A. 2001. Mercury Contaminated Material Decontamination Methods: Investigation and Assessment. U.S. Department of Energy. Technical Report Number FG21-95EW55094-02.

45 Bishop, P., R.A. Rauche, L.A. Reiser, M.T. Suidan, and J. Zhang. 2002. Stabilization and Testing of Mercury Containing Wastes: Borden Sludge.

46 Mattus, C.H. 2003. Measurements of Mercury Released from Solidified/Stabilized Waste Forms-FY2002. ORNL/TM-2002/283.

47 Bowerman, B., J. Adams, P. Kalb, R-Y. Wan, and M. LeVier. 2003. Using the Sulfur Polymer Stabilization/Solidification Process to Treat Residual Mercury Wastes from Gold Mining Operations. Feb. (Presented at the Society of Mining Engineers Conference, Cincinnati, OH, Feb. 24-26, 2003).

48 Mattus, C.H. 2003. Measurements of Mercury Released from Solidified / Stabilized Waste Forms-FY2002. ORNL/TM-2002/283.

ENDNOTES

49 Chattopadhyay, S., and W.E. Condit. 2002. Advances in Encapsulation Technologies for the Management of Mercury-Contaminated Hazardous Wastes.

50 Rieser, L.A., P. Bishop, M.T. Suidan, H. Piao, R.A. Fauche, and J. Zhang. 2001. Stabilization and Testing of Mercury Containing Wastes: Borden Catalyst. EPA/600/R-02/019.

51 Source: www.genetics.uga.edu

52 CAILLE Nathalie. 2002. Mobilité et phytodisponibilité du mercure dans des dépots de sédiments de curage (co-dir. : C. Leyval et J.L. Morel ENSAIA).

53 http://www.ncbi.nlm.nih.gov/pubmed/1777231

54 http://www.clu-in.org/products/site/complete/resource.htm

55 USEPA. 1990. Bio-Recovery Systems, Removal and Recovery of Metal Ions from Groundwater, USEPA 540/5-90/005a, August 1990.

56 Jose L. Gomez-Eyles et. al., 2013

57 Upal Ghosh et. al., 2012. Final Report, Activated Biochars with Iron for In-Situ Sequestration of Organics, Metals and Carbon, SERDP Project ER-2136, April 2012.

58 ERM verbal communications with industrial NICOLE member, February 2015, confidential site, USA

59 http://www.purolite.com/RelId/606267/ccptid/1394/productid/1434/isvars/default/chelation_resins.htm

60 http://www.tmt15.com/product/tmt15/en/about/heavy-metal-precipitation/pages/default.aspx

61 Blue, Van Aelstyn, Matlock, Atwood. 2008. Low-level mercury removal from groundwater using a synthetic chelating ligand, Water Research, Volume 42, pp 2025-2028.

62 http://sammsadsorbents.com/applications/mercury/

63 Looney, B. B., M. E. Denham, K. M. Vangelas, and N. S. Bloom. 2003a. Removal of Mercury from Low-Concentration Aqueous Streams Using Chemical Reduction and Air Stripping, Journal of Environmental Engineering, 129:819-825.

ENDNOTES


64 Huttenloch , Roehl, and Czurda. 2003. Use of Copper Shavings To Remove Mercury from Contaminated Groundwater or Wastewater by Amalgamation, Environ. Sci. Technol., 2003, 37 (18), pp 4269–4273.

65 Richard and Biester. 2013. Pilot study: Brass granule for the in-situ remediation of mercury in groundwater, Institute of Geoecology TUB, Poster at ICMGP Edinburgh, July / August 2013.

66 Goin J, D. Vlassopoulos, M. Larsen, and S. Germiat. 2014. Soil and Groundwater Mercury Remediation at a Former Chlor Alkali Plant. Presented at the Ninth International Conference on Remediation of Chlorinated and Recalcitrant Compounds, Monterey, California, May 2014.

67 Svensson, M, B. Allard. 2007. Leaching of mercury-containing cement monoliths aged for one year.

68 Oji, LN. 1998. Mercury Disposal via Sulfur Reactions. J. Environ. Eng. 1998.124:945-952.

69 Serrano, S, D. Vlassopoulos, B. Bessinger, and PA O’Day. 2012. Immobilization of Hg(II) by Coprecipitation in Sulfate-Cement Systems. Environ. Sci. Technol. 2012 46, 6767-6775.

70 Gibson, B.D., C.J. Ptacek, M.B.J. Lindsay, and D.W. Blowes. 2011. Examining Mechanisms of Groundwater Hg(II) Treatment by Reactive Materials: An EXAFS Study. Environ. Sci. Technol., 45, 10415–10421.

71 Zhang, FS, JO Nriagu, and H Itoh. 2005. Mercury removal from water using activated carbons derived from organic sewage sludge. Water Research, 39, 389-395.

72 USEPA. 1997. Capsule Report: Aqueous Mercury Treatment. U.S. Environmental Protection Agency, Office of Research and Development, EPA-625-R-97-004.

73 Barringer, J.L., Z Szabo, and P.A. Reilly. 2013. Occurrence and Mobility of Mercury in Groundwater. http://dx.doi.org/10.5772/55487

ENDNOTES


NOTES

NICOLENetwork for Industrially Contaminated Land in Europe

NETWORK FOR INDUSTRIALLY CONTAMINATED LAND IN EUROPE

www.nicole.org

Contact information: Roger Jacquet,SolvaySA,[email protected] Phipps,ERM,ol[email protected] Barrett,ERM,[email protected]

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