&fi6.-

SIMULATED COAL GAS MCFC POWER PLANT SYSTEM VERIFICATION

Technical St&us Report

for

June 1998

For Work Performed Under DOE Contract No. DE-AC21-90MC27394

Presentedlo

Contractor Reports Receipt CoordinatorU.S. Department of Energy

Morgantown Energy Technology Center3610 Collins Ferry RoadMorgantown, WV 26507

Presentedby

J.A. Scroppo, Project ManagerM-C Power Corporation

8040 South Madison StreetBurr Ridge, IL 60521

Reviewedby: ~ Authorizedby:.

7/W

T.G. Benja#in, Advanced Tec~ology Manager

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This Quarterly Technical Progress Report was prepared with the

support of the U.S. Department of Energy, under Cooperative

Agreement No. DE-FC21 -94MC31 175. However, any opinions,findings, conclusions, or recommendations expressed herein are

those of the authors and do not necessarily reflect the views ofthe DOE.

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DISCLAIMER

This report was prepared as an account of work sponsoredby an agency of the United States Government. Neitherthe United States Government nor any agency thereof, norany of their employees, make any warranty, express orimplied, or assumes any legal liability or responsibility forthe accuracy, completeness, or usefulness of anyinformation, apparatus, product, or process disclosed, orrepresents that its use would not infringe privately ownedrights. Reference herein to any specific commercialproduct, process, or service by trade name, trademark,manufacturer, or otherwise does not necessarily constituteor imply its endorsement, recommendation, or favoring bythe United States Government or any agency thereof. Theviews and opinions of authors expressed herein do notnecessarily state or reflect those of the United StatesGovernment or any agency thereof.

DISCLAIMER

Portions of this document may be illegible

in electronic image products. Images are

produced from the best available original

document.

TABLE OF CONTENTS

Executive Summary

Introduction

Laboratory and Field Work

Reports and Presentations

Outside Contacts

Administrative Aspects

Plan for the Next Quarter

Appendix A – Stabilization of Heavy Metal Containing Hazardous Wastes with

By-Products from Advanced Clean Coal Technology Systems

Appendix B – An Evaluation of the Long-Term Leaching Characteristics of Metalsfrom Solidified/Stabilized Wastes

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EXECUTIVE SUMMARY

During the thirteenth quarter of Phase 2, work continued on conducting scholarly work,

preparing for field work, preparing and giving one presentation, submitting. one manuscript, andmaking an additional outside contact.

Scholarly work

Jana M. Agostini, the graduate student assigned to this project from the Department ofCivil and Environmental Engineering, has concluded her work on evaluation of the long-term

stability of Phase 1 samples. On November 20 she submitted the final report on her M.S.

project, entitled “An Evaluation of the Long-Term Leaching Characteristics of Metals from

Solidified/Stabilized Wastes.” In her work she evaluated the long-term leaching characteristics

of six s/s waste samples. She found that cadmium and chromium remained tightly boundwithin the s/s matrix after two years. The leachability of lead and zinc from the s/s matrices

varied among the six samples after two years of curing.

r Field Work

The Mill Service Yukon Plant (MSYP)Department of Environmental Protection on

is awaiting-a response from the Pennsylvania

MSYP’S applications {1) for a minor permit

modification for the installation of a new silo and new storage pads and (2) for a revision to the

air permit to operate the bagnouse on the new silo.

Reuorts and 1’resentations

A presentation was made on “Autoclave Cellular Concrete Research at the University

of Pittsburgh: Physical and Environmental Properties” to the Coal Technology Group of thePittsburgh Section of the American Chemical Society.

A manuscript on “Stabilization of Heavy Metal Containing Hazardous Wastes with 13y-

Products from Advanced Clean Coal Technology Systems” was submitted to the editor of the

Journal of the Air & Waste Management Association.

Outside Contacts

Discussions by internet were held with Dr. Avinash Chandra, Chief Scientific Officer ofthe Centre for Energy Studies of IIT, Delhi, concerning a possible visit by him to the School of

Engineering Center for Environment and Energy here in Pittsburgh. Unfortunately, the additional

cost of the airfare, incurred in changing the airline ticket he held for the trip he was planning

to the United States, was prohibitive, and plans for a visit by Dr. Chandra to Pittsburgh on thistrip were canceled.

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s for the Next Quarter

During the quarter from December 30, 1998 through March 30, 1999, work on Task 1

of Phase 2 will continue. The principal investigator will maintain contact with MAX

Environmental Technologies, Inc., as it plans the installation of equipment at the Mill ServiceYukon Plant to conduct Phase 2 of the project.

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INTRODUCTION

This seventeenth quarterly report describes work done during the seventeenth three-

month period of the University of Pittsburgh’s project on the “Treatment of Metal-LadenHazardous Wastes with Advanced Clean Coal Technology By-Products~”

This report describes the activities of the project team during the reporting period. The

principal work has focussed upon new laboratory evaluation of samples from Phase 1,

discussions with MAX Environmental Technologies, Inc., on the field work of Phase 2, givinga presentation, submitting a manuscript and making and responding to one outside contact.

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LABORATORY AND FIELD WORK

Scholarlv Actlwtv. .

Jana M. Agostini, the graduate student assigned to this project from the Department ofCivil and Environmental Engineering, has concluded her work on evaluation of the long-termstability of Phase 1 samples. On November 20 she submitted the final report on her M.S.

project, entitled “An Evaluation of the Long-Term Leaching Characteristics of Metals fromSolidified/Stabilized Wastes.” Here is the abstract of the report:

Current hazardous waste treatment standards are based on the premise

that the leaching properties of stabilized/solidified (s/s) wastes do not

significantly change with time. However, numerous studies have examined the

mineralogical changes which occur in s/s wastes with time. Changes in the

mineralogy of the s/s matrix could cause changes in the microstructure, which

may influence the leachability of hazardous constituents in the s/s matrix. The

objective of this research was to evaluate the long-term leaching characteristicsof s/s waste samples (originally prepared during [Phase 1 of this project] at the

University of Pittsburgh) by analyzing the available s/s waste samples; and to

support such results with a review of the literature in this area. Six s/s wastesamples, remaining from [Phase 11, were examined to evaluate changes in theleachability of cadmium, chromium, lead and zinc as a result of aging. In order

to measure changes, the six original s/s waste samples were retested using theToxicity Characteristic Leaching Procedure (TCLP) and the Shake Extraction Test

(ASTM D 3987-85) after two years of curing. Cadmium, as measured in theTCLP Ieachates of the six samples, remained immobilized after-two years, as

expected based on the literature review. Chromium also remained tightly bound

within the s/s matric after two years, in agreement with previously published

results. The leachability of lead from the s/s matrices varied among the six

samples after two years of curing. This result is expected based on the noted

mechanisms for lead immobilization found in the literature. Similar to lead, the

concentration of zinc in the TCLP Ieachates of the two year old samples varied.

The varying results for zinc stabilization may be expected according to themechanisms desribed for zinc immobilization presented in the literature. Inaddition, the shake extraction test Ieachates contained lesser concentrations of

cadmium, chromium, lead and zinc than did the TCLP Ieachates for each of the

six s/s wastes examined. This result is expected since the shake extraction test. .used a less aggressive extraction fluid (near neutral pH) than does the TCLP.

The full report is reproduced in Appendix B.

The Mill Service Yukon Plant (MSYP) is awaiting a response from the PennsylvaniaDepartment of Environmental Protection on MSYP’S applications (1) for a minor permit

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modification for the installation of a new silo and new storage pads and (2) for a revision to the

air permit to operate the baghouse on the new silo.

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REPORTS AND PRESENTATIONS

On October 20 the co-principal investigator made a presentation on “Autoclave CellularConcrete Research at the University of Pittsburgh: Physical and Environmental Properties” tothe Coal Technology Group of the Pittsburgh Section of the Americari ‘Chemical Society.

On November 2 the co-principal investigator submitted a final version of a manuscript

“Stabilization of Heavy Metal Containing Hazardous Wastes with By-Products from AdvancedClean Coal Technology Systems” to the editor of the Journal of the Air& Waste ManagementAssociation. A copy of the manuscript is provided in Appendix A.

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OUTSIDE CONTACTS

Jndian lnsilute of Technoloav. Delhi

On October 10 Dr. Avinash Chandra, Chief Scientific Officer of the Centre for EnergyStudies of IIT, Delhi, suggested that his travel itinerary to the United States be modified to

allow lim to come to Pittsburgh from St. Louis, where he would be attending the IEEE IndustrialApplications Society Conference on October 14. He wished to come to Pittsburgh on October

15 to follow up on the exchange of correspondence between the School of Engineering Centerfor Environment and Energy (ECEE) and Prof. C. N. K. Bansal, Head of the Centre. He noted

that Prof. Bansal wishes to initiate some programs of mutual interest, which he hoped that Dr.

Chandra could discuss in person with the staff of ECEE. It was determined that, unfortunately,

the additional cost of the airfare, incurred in changing the airline ticket, was prohibitive, and

plans for a visit by Dr. Chandra to Pittsburgh on October 15 were canceled.

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ADMINISTRATIVE ASPECTS

This section provides the monthly highlights and closes by comparing progress with themilestone chart.

Swcial Act cmi

There were no special actions during this quarter.

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Here are the highlights of the thirteenth three-month period of the second phase of the

project.

Swte mber 30- Octobe r 30, 1998

● Presentation is given on autoclave cellular concrete to the Coal Technology

Group of the Pittsburgh Section of the American Chemical Society.

Octobe r 30- Novembe r 30, 1998

● Final manuscript describing Phase 1 is submitted to the Journa/of the Air &Waste Management Association.

● Graduate student presents her final report on long-term stability of six samples

from Phase 1.

November 30- December 30, 1998

NONE

an-son of Proaress w ith Milestone Chart

The following task for Phase 2 had been scheduled for completion during the first

quarter of Phase 2:

● Task 1 - Test Plan for Phase 2

Task 1 still was not completed during the thirteenth period of this phase. The decision in early

April 1996 by METC that an environmental assessment of the Phase 2 project at the Yukon

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plant of Mill Service, Inc. (MSI), would have to be conducted and the subsequent withdrawal

in late April 1996 by MSI from Phase 2 necessitated a search for a new subcontractor to host

and participate in the commercial test of Phase 2. MAX Environmental Technologies, Inc., hasrejoined the project team and is designing modifications at the Mill Service Yukon Plant (MSYP)

to enable it to enter this business area and carry out the field work on.this project. The testplan for Phase 2 will be prepared shortly before the permits are in place for the installation of

the equipment at MSYP for carrying out the demonstration.

Work has been suspended on two tasks from Phase 1:

● Task 4- Treatment of Metal-Laden Waste with CCT Solid By-Product

● Task 5- Data Analysis

The fourth by-product and the final three residues are no longer being actively sought.

When the Phase 2 testing program is initiated, consideration will be given to reestablishing this

activity.

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PLAN FOR THE NEXT QUARTER

During the quarter from December 30, 1998 through March 30, 1999, work on Task 1

of Phase 2 will continue. The principal investigator will maintain contact with MAX

Environmental Technologies, Inc., as it plans the installation of equipment at the Mill ServiceYukon Plant to conduct Phase 2 of the project.

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APPENDIX A

STABILIZATION OF HEAVY METAL CONTAININGHAZARDOUS WASTES WITH BY-PRODUCTS FROMADVANCED CLEAN COAL TECHNOLOGY SYSTEMS.-

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STABILIZATION OF HEAVY METAL CONTAINING HAZARDOUS WASTES WITHBY-PRODUCTS FROM ADVANCED CLEAN COAL TECHNOLOGY SYSTEMS

Jesse W. PrittsUnited StatesEnvironmentalProtection Agencywashingto~ Dc

Ronald D. Neufeld and JamesT. CobbUniversityof PittsburghPittsburgh PA

IMPLICATIONS

The 1990 Clean-Air-Act Amendmentsinstituteda reduction in atmospheric sulfhrdioxide

emissionsfrom coal-fired power plants.To meet these reductions, anew generationof advanced

coal combustion systems develop~ designedto be environmentallycleaner andmore eflicient.... .

thanconventional coal-burning processes. These systemseffectively remove sulfbrdioxide formed

duringcoal combustio~ preventingits releaseto the atmosphere.The disposal of residues

produced by these systems is becoming increasinglyproblematic. The waste management

community is actively searchingfor beneficialuses for these residues. One potentialapplicationis

the use of these materialsas treatmentchemicalsfor hazardouswastes.

ABSTRACT

The purpose of this investigationwas to evaluatethe success of residuesfkom advancedClean

Coal Technolo~ (CCT) systemsas stabiition agentsfor heavy metalcontaininghazardous

wastes. k the context examinedhere, Stabii[on refm to techniquesthatreduce the toxicity of

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a waste by converting the hazardousconstituentsto a less soluble, mobile, or toxic ford. Three

advanced CCT by-products were used: coal-waste-fired circulatingfluidti bed combustor

(CFBC) residue;pressurizedffuidd bed combustor (PFBC) residu~ and spraydrierresidue.. .

Seven metal-ladenhazardouswastes were treated: three contaminatedsoils; two airpollution

control dusts;wastewater treatmentplantsludge, and sandblastwaste. Each of the seven

hazardouswastes were treatedwith each of the three CCT by-products at dosages of 10%, 30Y0,

and 50°/0, by weight (by-productwaste). The treatmenteffectivenessof each mixturewas

evaluatedby the Toxicity CharacteristicLeaching Procedure (TCLP). Of the 63 mixtures

evaluat@ 21 produced non-hazardousresidues. Treatmenteffectivenesscan likelybe attributed

to mechanismssuch as precipitationand encapsulationdue to the formation of hydratedcalcium

silicates and calcium sutio-aluminates.Results indicatethatthese residueshave potentialbeneficial-----

uses to the hazardous waste treatmentmmmmity, possibly substitutingfor costly treatment

chemicals.

INTRODUCTION

The passage of the 1990 CleanAir Act Amendmentsprompted the development of a numberof

innovativetechnologies designedto reduce atmosphericSLMU-dioxide emissionsfrom coal-tired,.

power plants.Fluid*-bed combustors and advanced scrubbersare two such technologies which

have successfidiy progressed from the laboratory phase to commercial-scale fiwilities.These

systemsremove sulik dioxide by reaction with a sorbent such as limeor limestone.Reactions can

take place in the combustor as the coal bums, as with fluidized-bedcombustors, or by reaction

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with the flue gases tier the combustion process,eitherin the ductwork Ieadimgfrom the boiler or

in advanced scrubbers. The residuesobtained, while highlyvariabledependingon the composition

of the coal fed to the boiler and the type and operating conditions of the sulfbr-removal

technolo~ US* are typicallymixturesof fly ash the primaryreaction product (anhydrite-

CaS04, or calcium sulfite - CaS03%HzO), andunreacted sorbent. The high alkalinityof these

residues along with the high concentrations of free lime make them potentiallyusefi.das treatment

agents for heavy metal contaminatedhazardouswastes. Specifically, these residueshave

neutraliz.atio~sorptio~ and cementitiousproperties that makethem highlyuseiid as stabiition

reagent#.

There has been an extensiveamount of researchinto the stab~tion reactionsthatoccur.... .

in cement-based and fly-ash-basedtreatmentsystems, however littleresearchhasbeen conducted

evaluatingthe stabiition effectiveness of advancedcoal-combustion and.CCT by-products.

Stabiition reactions area complex ‘&teractionof several competing mechanisms,each of which

can help or hinderthe overall stabilizationeffectiveness of the system. Cementitiousand

pozzolanic based treatmentsystemsrely on a numberof mechanismsto control contaminant

release, i.ncludmgsolubiity changes due to pH contro~ formation of insolublechemical species,

and encapsulation.

Cementitious materialssuch as portlandcement have been widely ustxfas stabiition

agents, and the &emistry of these systems is well documented. Cementitiousmaterislssuch as

portkmd cement are basicallya calcium silicatemixturecontainingpredominantlytricalciumand

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dicalciumsilicateswith smalleramountsof tricrdciumaluminateand a calcium ahuninofemite.

Typical weight proportions in an ordinarycement are 50’% tricalciumsilicate,25% dkalcium

silicate, 10°/0trhxdciumaluminate,10°/0tetracalciumaluminoferrite,and 5°/0other oxides. In the. -.

presence of water, the four major crystallinecompounds.hydrate.The calcium silicateshydrateto

form the compounds ezdciumhydroxide and calcium silicatehydrate(tobermorite gel). Tricalcium

aluminatereacts with water and calcium hydroxide to form tetracalciumaluminatehydrate.

Tetracalciumahminoferritereactswith water to form calcium aluminoferritehydrate.Tricalcium

aluminate,gypsuxq and water may combine to form calcium sulfoalurninatehydrate.The basic

reactions are as follows3:

2(3 CaO”SiO~ + @()

TricrdciumSilicate

2(2CaO”SiO~ + 4~o

Dkaicium silicate

3CaO”Alz03 + 12 HZO

Tricalcium aluminate

4CaO”AlzO~”F~O~+ 10~0

Tetracalciumalu&noferrite

+ 3CaO”2Si02.3Hz0

Tobermorite gel

+ 3CaO”2SiOz*3Hz0

Tobermorite gel

+

+

Ca(oH),

Calciumhydroxide

2Ca(OH)1!

Calcium hydroxide

+

+

-#

-+

3ca(oH)2. .

Calciumhydroxide

ca(oH)2

Calcium hydroxide

3&()”M20,”&l(()@,” 12H20

Tetracalciumaluminatehydrate

6tiOA120~*F~03” 12&0

Calciumaluminoferritehydrate

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3CaO”AlzO~ + 10HZO + C%SO(2HZ0 +

Tricalcium ah.uninate Gypsum

3CaO”AlzO~.CaSOe” 12H20

Calcium monosuffoaluminatehydrate

Insufficient sulthteis present the reaction product of the last reaction is hydratedcalcium

aluminatest.dfate(ettringite: 3ti0-~20~”3C&Oq”32HzO) which coats the surfacesof the

particles, preventingfkther rapid hydration.This is why gypsum is ofien added to cement as a set

retarder.If gypsum is not presentin substantialamounts, calcium aluminumhydratesform ahnost

immedutely and the system sets.

By-products ftom advanced CCT systemstypically exhibh cementitiousproperties. The fly

ssh content along with the unreacted lime present allows these materialsto enterinto pozzolanic..

reactions upon the addition of water. The reactions that occur in dry CCT-based systemsare

analogous to those that occur with portland cement. In general, however, thesereactions are

slower thanthose of cement and do not produce the same products. Specifically, the limereacts

with SiOz fkom soluble silicatesto form calcium silicate,which thenhydratesin the samemanner

as portland cement. One exception is thattricalciumsilicateis not formed duringthisprocess4.

The tricalcium silicate in portlandcement is primarilyresponsiblefor the development of strength

in pofiland cement rnixtures3.Consequently, the finalproperties of CCT residue systems

frequently are not as good as portkmdcement mixtures.CCT by-products can contain large

amounts of gypsum. ASIa resul~ hydrationof these residuesis often accompanied by substantial

formation of chemical species of the ettringitefdy.

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MATERIALS

The materialsrequired for thisevaluationwere of two types: CCT by-products and hazardous

wastes. There are no standardmethods for samplingof CCT by-products, so methods”used for

cement andfly ash were used. Samplesof by-products were collected using samplingprotocols

conforming to ASTM C-311 (Test Methods for Samplingand TestingFly Ash or Natural

Pozzolans for Use as a MineralAdmixture in Portland-CementConcrete). When possible, samples

were collected directly from the ash storage silos at the generatingfaciity. When thiswas not

possible, sampleswere collected ilom the trucks or railcars used to transportthe materialsto

disposal sites. Since coal fdstocks, production ratesand operatingconditions of the combustors

do not vary significantlyon a day to day basis,,samplesof by-products thatwere collected were..

expected to be fairly homogeneous. Waste sampleswere collected from bulk samplesat the

hazardouswaste TSD fhciity. Prior to offloading of the wastes from the ticks, sampleswere

collected fi-oma minimumof three locations along the le@ of the shippingcontainer. Bulk

samplesof both wastes and by-products were reduced to laboratory size in accordance with:.

ASTM C700-87 (StandardPractice for Reducing Field Samplesof Aggregate to Testing Size).

CCT lBy-Products

In advanced CCT systems, suhiiris removed in the combustor as the coal bums or from the flue

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gases by reaction with a sorbentsuch as lime, limestoneor dolomite. Fluid~ bed combustors

typicalluse limestone or dolomite as sorbents,,while spraydriersuse a Iimeslurry.In fluid~ed bed

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In a spraydrier, a lime slurryis preparedby mixing limewith water. This slurryis then

sprayed into a tower through which the hot flue gases andfly.ash pass. The lime combmes with.. .

the sul.fbrdioxide, forming oalcium sulfateor sulfite according to the lattertwo of the three

reactions above. The excess water in the slurryevaporates in the tower, producing a dry residue.

Three advanced CCT by-produots were evaluatedfor theireffxtiveness as stabiition

agents for metal-containinghazardouswastes. Two of the by-products were obtained from

fluidii bed combustors, and one was from a spray drier.

CircuLrtingFluidizedBed Combustor Resi&e. This materialis by-product from a coal-,.

waste-fired circulatingfluid~ bed combustor (CPJ3C)operated by the Ebensburg Power

Company at Ebensbur~ PA, The coal waste fed to the boiler has a sulfi.wcontent between 1.4 and

2.O’XO.Sulfir released duringcombustion of the coal waste is removed in the boiler as the coal

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cornbustors, the sorbent is fed into the-boiler along with the coal. As the sorbent is heated, the

carbonate mineralsin the limestone are calcined to act as a sorbent for sulfhrdioxide thatis

released duringthe combustion of the cd. This mixtureof fly ash reactio~ products and any

unspent sorbent are then removed by particulatecontrol systems.The reactions are

CaCO~ -i- Heat ~ CaO + C02

CaO + SO* + CaS03

CaO + so, + 1/202 + CaSOz

burns. In the combustor, crushed coal is mixed with limestoneandis suspended on jets of air.This

bed of coal and limestone floats insidethe boiler, tumblingmuch like a boiling liquid. As the coal

burns, suifk that is released combmes with the limestonebefore it ean esqtpe the boiler. More

than90% of the sufir released from the cord can be capturedin thismanner.The sulfhr-laden

limestoneforms a dxywaste product thatis removed with the coal ash. Approximately 30% of the

residueis removed as bed ashthrough the bottom of the boiler, while the remaining70°/0is

carriedout of the boiler with the fly ash and is removed in a baghouse. The bed ashand the fly ash

areconveyed to a silo, where they are mixed for storage; The residueis designed to contain 82°/0

ash 12.5V0limestone equivalent and 5.5°A CaSO#2aSO& Approximately 200,000 tons of this

materialis being produced annuallyat the Ebensburg combustor.

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PressurizedFIuidizedBed CombustorResidue. Thisby-product is from a coal fired

pressurizedfluidized bed combustor (PFBC) operatingat the Tidd stationof Ohio Power

Company, a subsidiaryof AmerieanElectric Power Corporation%atBrilliant Ohio. A PI?BCis

operated at a pressure severaltimes greaterthanatmosphericpressure,producing residuewith

dfibrent properties thantypical CFBC residue.The sorbent fti to thisplantwas dolomite

(CaMg(CO,)~. Dolomite was used at the Tidd stationbecause its sulfhtedproduct was both more

porous (and thus more reactive) and easierto handlethanthatfrom limestone.By operating at. .

high pressure, little of the dolomite in the residueis in the oxide form but is mostly presentas

carbonate. The dolomitic characterof the sorbent yields a residuethatis lower in pH thanthat

produced from tie-based sorbents.By-product from the eombustor is removed both as bed ash

and with the fly ash. The investigationsperformed hereutilizedonly the residue removed with the

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fly ash. The Tldd stationwas a demonstrationfacilityand is no longerin operating status.At the

time of collection of the residuesused in this investigatio~ the by-product contained 50-60’XO

equivalent CaCO~, -2% availableCaO, and approximately40-50% fly ash.

Dry Scrubber Residue. This by-product is spraydry residuesuppliedby CONSOL, Inc.,

from a Joy NUOspray drier. This materialis produced by the cogeneration project of Chambers

Cogeneration Limited Partnership,operated by U.S. OperatingServices Company at the Carney’s

Point Cogeneration Planton the grounds of DuPont’s ChambersWorks in New Jersey.The spray

drier at Carney’s point is the iirst one on a pulverizedboiler burninghigh-suti easterncoal. At

Carney’s Poin$ the cd is burnedin a conventionalboiler. The SOZladen flue gases are dweoted

to a spray d~ tower. In the tower, a lime slurryis sprayedt~ough the hot fhtegases as they rise.. .

through the tower. The lime combmes with the sulfbrdioxide, andthe sulfbr captureresiduerises

through the upper port of the tower with the fly ash.Because the flue gases are ho~ the water

from the lime slurryis vapo~ therefore producing a d~ residue.The combined solids are

captured in a baghouse and directedto a silo for sto&ge. The residueis designedto contain 45°/0

fly as~ 36% CaSO&aSO~, 10% Ca(OH)= 2% CaCO~,and 7% other inertmaterial.

Approximately 100,000 tons of residue is produced at Carney’s Point each year.

Hazardous Wastes

Seven hszardous wastes were selected to be treatedwith the threeCCT by-products. Wastes

evaluatedwere a wastewater treatmentplantsludge, three contaminatedsoils, two airpollution

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control dusis, and a sandblastwaste. A description of each of the wastes is presentedin Table 2.

Each of thesewastes were characteristicallyhazardousdue to the presence of heavy metalsin the

TCLP extractin excess of the limitsspecified in 40 CFR$261.24 (Toxicity. Characteristic).Under

the Toxicity Characteristic,the extract obtained from the TCLP is analyzedto determineifit

possesses any of 39 toxic contaminantsat levels identifiedby EPA as being a riskto humanhealth

or the environment.If the TCLP extract contains anyof the 39 contaminantsin excess of the

limitsexpressed in the Toxicity Characteristic,thenthe waste is considered hazardousand must

be treatedprior to being land disposed. Table 2 summarizesthe eight metalscurrentlyregulated

underthe Toxicity Characteristic,the Hazardous Waste Number assignedto each by EPA the “

reference levels based on the National InterimPrimaryDrinkingWater Standardsat which each of

the metalsexhibk chronic toxicity, andthe regulatorylevels above which the metal is at a..=-. -

hazardousconcentration in a waste. It should be noted thatthe regulatorylevels are 100 times the

chronic toxicity regulatorylevels. This 100 fold fiwtor is a dilutionand attenuationfactor which

estimatesthe ddution expected of the toxic constituentsas they travel from the point of leachate

generation(iie., the landfill)to the point of humanor environmentalexposure (i.e., a drinking

water well)s. Since this investigationonly addresseswastes thatare contaminatedwith inorganic

compounds, the other 31 compounds regulatedunderthe TC are not included in Table 1, and

were not analyzedfor throughoutthis investigation...

EXPERIMENTAL PROCEDURES..

There were three goals of the experimentalinvestigations:(1) Characterizationof the major

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physical and chemical properties of each of the CCT residum, (2) Evaluationof the metal

leachabilityof the seven hazardouswastes and the threeby-products; and (3) Evaluationof the

stabilizationeffectiveness of each of the three CCT residueswhen used to treateach of the seven

hazardous wastes. Experimentalprocedures utilized,unless otherwise indicated,are standard

methods presented in eitherSW-84&or the AnnualBook of ASTM Standards’.

Characterization of CCT By-Products

Each of the three CCT by-products were analyzedto determinea wide range of physical

properties and chemical constituents.A thorough characterizationand a.dysis of the by-products

was necessary in order to betterunderstandthe chemicalmakeupof the residues,as well as to...

give an indication of their suitabilityfor use in stabtition systems.Ten samplesof the CONSOL

spraydrier residue, ten samplesof the Tidd PFBC residue andtwelve samplesof the Ebensburg

CFBC materialwere collected for evaluation. Evaluationsconducted consisted of elemental

chemical analyses,alkalinityand acid neutralizatio~physicalproperties, and measuresof

reactivity.The speciiic tests conducted were:

Eiemental ChemkmlAn@ysis. Major elementalcomponents were reported in the

geochemical oxide format CaO, MgO, F~O~, AlzO~,C02, SiO= sulfatesulik as SOS,sulfite

sulfimas SOZ and loss on ignitionat 600 and 1100”C. Standardwet analysisprocedures of

ASTM C-1 14 ~d ASTM C-25 were followed.

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Alkalinity and Acid Neutralization. Parametersreported were pm flee or availablelime,

andtotal neutralizingpower, also called calciumcarbonate equivalency (CCE). ASTM C-25,

ASTM D-1293, and ASTM C-602 procedures were followed for all analyses..-.

Physical Properties. The propertiesdetermined and the corresponding procedures

utilizedwere.

- Particle specific gravity(gas pycnometer)

- Bulk density, loose, d~ (ASTM C-33)

- Bulk density, compact dry (ASTM C-33)

- Bulk density, as received---- . -

FhKne&l

- Particle size distribution(minus8 mesh)

- % passing no. 200 and no. 325 sieve @STM C-430)

- BET SpeCifiCSUlfiCearea (Asm D-4567)

- Blaine fineness (ASTM C-204)

12eactivi~. Each of theby-products were analyzedin order to gain a measureof their

reactivityand an indkation of theirstabbtiolnpotential. The thermalreactivi~’or temperature

rise fi-omhydration of quicklimeand anhydritewas measuredby ASTM C-110. The heat

generatedis important for some stabiition objectives and to determineif availablelime is

.*

.

12 ,.

.‘

<

presentas quicklime (anhydrous) or hydratedlime. The stabi!iition or fixation capacity of the by-

products with water was determinedby a ChemicalWaste _ement procedure called the

Mixed Ratio. The Mixed Ratio is a comparativetest used to determineho-wmuch materialis

needed to absorb one gallon of water. This testis usefid for determiningthe abilityof a materialto

absorb water, which gives an indication of the stabilizationpotentialof the material.

value of the Mixed Ratio, the higherthe water absorbing capacity of the material.

The lower the

Metals Analysis of Hazardous Wastes and CCT By-Products

Each of the seven hazardous wastes were analyzedto determineboth the total concentrationsand

TCLP acid-leachable concentrations of the eight metalscuryentlyregulatedunderthe Toxicity.. .

Characteristic.Toial metalsevaluations,which involve vigorously digesting analiquot of waste in

a strong acid solutio~ gives an indication of the total quantitiesof metalspresentin the sample.

These quantitiesare reported on a mass per mass basis (mg metalper kg of waste). TCLP metals

evaluationsmeasure the concentration of metalsthatleach from the solid-phase of a waste sample

which is extracted in fi acetic acid solution. Two buffered acidic solutions areus~ the choice of

which depends upon the alkalinityand buffering capacity of the materialbeing leached. The

sampleis extracted in a rotary extractor for a period of appro~tely 18 hours. The TCLP test is

designedto simulate leachingcondhions to which a waste disposed of in a municipallandfillmay

be exposed. Each of the T(2LP extracts of the seven hazardouswastes were analyzedto determine

the concentrations of the eight metalslisted in Table 2, andto determinewhich of the metalswere -

presentin hazardous concentrations.

13

*&

,

Each of the by-products were also analyzedfor total and TCLP metals. Although coal

combustion by-products are categoricallyexempt from regulationas solid wastes under40

CFR$261.4 and usually do not exhibittoxicity characteristicsfor metals, it is usefi.dto determine

the environmentalproperties of these materialssince coal combustion residuescan contain

relativelyhightotal concentrationsof metals.

.

Evaluation of the Stabilization Effectiveness of CCT By-Products

Treatabilitytests were conducted with each ofthethreeby-products to determinethe extentto

which the metals present in each of the hazardouswastes could be stabilized.These evaluations

consisted of mixing proportionate amountsof each waste with each by-produ~ adding sufficient

waterto wet each mixture, andpefiorming a TCLP both immediatelymidafter 24 hours. The

imnxdate TCLP was conducted to determinethe degree of metal stabilizationwhich occurs

withina few minutes afler treatment.Immedkte TCLPS are frequentlyused by waste treatersto

evaluatethe effkct.ivenessof the treatmentprocess. If the immedate TCLP indtcatesthatthe

treatedwaste has been renderednon-hazardous, the materialcan be preparedfor shipmentto the

finaldisposal site. If the immedate TCLP indicatesthatthe waste is stillhazardous, then

addh.ionaltreatmentis required.A 24-hour TCLP was also conducted on the treatedwastes to.’

confirm the treatmenteffectiveness.Many treatersstore wastes for a 24 hour period and conduct

a TCLP to contirrnthe treatmentei%ctiveness prior to shipmentto finaldisposal. Mixture

proportions of the treatabiity studiesconsisted of mixing200 gram rdiquotsof each of the seven

wasteswith 10°/0,30°/0, and 50°/0,by weighg of each of the threeby-products. This produced a

14 ,,

. *

.<

total of 63 mixtures, from which 126 TCLP extractswere prepared (both an immedate and a 24-

hour TCLP for each mixture). Each of these TCLP extractswere analyzedfor the eight metals

listed in Table 1 in order to determineif the treatmentsrenderedthe wastes non-hazardous.

RESULTS

Characterization of CCT By-Products

The resultsof the gee-chemical analysisof the three CCT by-products are summarizedin Table 3.

This analysisirdcates that each of the by-products contain appreciableamounts of unreacted

sorbents. The spray-drierresidue, which is a lime syste~ contains25.41’% CaO. The CI?BC..

system which uses limestone as a sorben~ contains 11.06% CaO in tie residue. The PFBC

syste~ which utilizes dolomite as a sorben~ has a large percentage of both-MgO”(14.38%) and

CaO (22.13Yo) in the residue. Each of the threeby-products also contain large percentagesof

silico~ iro~ and aluminumoxides, which can be attributedto the fly ash content of each. As

expect~ significantamounts of sdir are pre&nt in each of the residues. The PPBC and CFBC

residuescontain suh predominantlyin the sulfatephase, while the spraydrier residue contains

mostly sulfitesulfix. This is because the PFBC and CFBC residuesare produced at much higher

temperaturesthanthe spray drierresidues.As a result the sulk is oxidzed to a higherextentin

thePFBC and CFBC systems.

Table 4 summarizesthe reactivityof each of the threeby-products. The temperaturerise

15

.

gives an indkation of the amountof heatgeneratedby the hydrationof quicl&me and anhydrite.

A highertemperaturerise usuallyindicatesthatmore lime is presentin the anhydrous(quicklime)

state. The spray drier residuehad the lowest temperaturerise of the threeby-products. This is

because this system uses a lime slurry,and even though the by-product is dry, most of the free

lime is stillin the hydrated state.All three of the residueshad high pH values, as well as high

calcium carbonate equivalences. The spraydrierresidue andthe PFBC residuehad particularly

high alkalinitiesas is evidenced by the highvalues for CCE, indicatingthatthese materialsmay be

particularlyusefil for neutralizinghighlyacidic wastes. Each of the threeby-products had a high

stabilizationcapacity as measuredby the mixed ratio, with the spraydrierresiduehavingthe

higheststabilizationcapacity of the three.

-.. .

Table 5 summarizesthe physicalproperties of the three CCT by-products. In general, the

by-products can be characterizedas fine-grain~ high surfhce-areamaterials.The spraydrier

residue has the greatest finenessof the three as measuredboth by theBlaine airpermeability

apparatusandby 0/0passing 80 mesh sieve, smallestaverage particlesize, as well as the lowest

specific gravity and lowest bulk density.The PFBC residuehasthe highestspecific gravityand

bulk density, as well&a highfinenessas measuredas ‘Yopassing80 mesh sieve. The CFBC .

materialhas the largest averageparticlesize, which is due to its highbottom ashcontent...

Measures of fineness, eitherthroughthe use of the Blaine airpermeabilityapparatusor a sieve

analysis,gives an importantindkation of reactivity.Finenessafikctsthe rate at which heat is

..released duringhydration as well as the rateof chemical reaction. Greaterfinenessincteasesthe

rate of hydration and thus acceleratesthe formation of pozzolanic compounds. Type I portland

16 . .

<

cement has a fineness of approximately3700 cm2/gmas measuredby the Blainefinenessand

85%-95% is finer than 45 rnicronf. Fly ashtypicallyhasparticlesizes in the range of 1 to 50

microns and a surface area in the range of 3000-5000 cm2@n3. In compariso~ the by-products

have a Blake fineness greaterthanboth portlandcement andfly ash. The average particle size of

the spraydrier residue and the PFBC residueis comparableto portkmdcemen~ while the average

particle size of the CFBC materialis greaterthanportkmdcement due to its bed ash content.

Overall, the high freeness and smallparticlesizes of the by-products indicatethatthey have the

potentialto rapidly enter into hydrationreactions,which is a good indicatorthatthey will be

successfi.dstabiition agents.

Metals Analysis of Wastes and By-Products.

Each of the seven hazardous wastes were analyzedto determinethe total concentrationsas well

as the leachable concentrations of the eight metalsregulatedunder the toxicity characteristic.This

data is presented in Table 6. Each of the sevenwastes containconsiderable total concentrationsof

severalmetals, most notably cadrniurqchromiumand lead. In each case, lead was the ‘only metal

which leached in excess of the TCLP regulatorylimits.

The total metals andTCLP metalsdataof the threeCCT by-products is presentedin Table

7. Arsenic, barium and chromiumwere presentin notable quantitiesin the by-products as

indicatedby the total metals concentrations.However, TCLP leachatesof the by-products

indkate thatnone of these metalswere leached to any significantdegree. This is likely due to the

17

,.

.

high alkaliity of the materials, which can effectively neutralizethe acidhy of the TCLP extraction

fluid.

Stabilization Effectiveness of CCT By-Products -..

Treatabilitytests were conducted to evaluatetheabilityof each of the three CCT by-products to

stabti the heavy metalspresentin each of the seven hazardouswastes. Each of the wastes were

treatedwith each of the by-products at three diierent dosages (10%, 30Y0,and 50V0,by weight).

The appropriateextraction fluid for each mixturewas determinedand TCLPSwere conducted on

each of the combinations both immediatelyand after a 24-hour mellowing period. Due to the high

alkalinityof the by-products, extractionfluidNo. 2 was requiredfor each of the 63 mixtures.

Treatmentswere considered successful if the concentrations of the eight heavy metalsregulated.:- ..

under the toxicity characteristicwere below the establishedregulato~ levels in an immediate

TCLP and in a cmfirmation TCLP cmducted after 24 hours. Of the 63 mixturesevaluat@ 21

produced treated residueswhich met therequired criteria.The success of the stabilization

evaluationsvaried for each of the threeby-products, as well as with each of the sevenwastes.

Table 8 illustrateseach of the combinationsevaluatedand indicatesthe successor failureof each

of the 63 mixtures. The spraydrierresiduewas the most successfid of the three stabilization

agents. This materialproduced 15 non-hazardousmixturesout of 21 evaluations.The PFBC..

residue produced 4 non-hazardousmixturesout of 21 evaluations,and the CFBC residueonly

produced 2 non-hazardous mixturesout of 21 evaluations.Table 9 summarizes’theconcentrations

of cadmium and kztd (~e only metalswhich had concentrationsabove TCLP limits)presentin the

treatedwastes in both the initialand 24-hour TCLP’S.

1s

.*

The spray drier residuewas successii.din reducingthe leachableconcentrationsof the

eight TC metalsbelow regulatorylevels both immediatelyand after 24 hours at allmixtureratios

with five of the seven wastes treated.These wastes were the batterysludge, the munitionssot

the industrialsite soil, the wastewater treatmentplantsoil, andthe sandblastwaste. Figure 1

illustratesthe lead concentrations presentin the immdlate TCLP Ieachatesof each of the 21

mixturesprepared with the spray drierresidue.The reductions in lead concentrationsin the

Ieachatescan easily be seen. In some instances,reductionswere greaterthantwo orders of

magnitudefi-omthe concentrations found in the leachatesof the untreatedw%tes, andwell below

the regulatorylimit of 5 mg/1.

....

In general, dfierences in leachablemetalsconcentrationsbetween irnmdlate and24 hour

TCLPSwere minor. However, therewere severalinstanceswhere notable dMerences occurred,

Mixtures of the spray drierresiduewith the BOF dust passed the imnxdate TCLP at the 10%

dosage, but fkiled to remainstabilizedtier 24 hours. The 30% mixturewith thiswaste fhiledboth

the immediateand 24 hour TCLPS due to highlead concentrations,andthe 50% mixturefailed

the imme&ate TCLP due to lead leachabilitybut passed after24 hours. The mixturesof this

residuewith the incineratordust succedidly stabiied the lead presenth the waste, but failed at

all tl&e mixtureratios both inumxbtely and ailer 24 hours due to high cadmiumconcentrations

in the leachates.

Without a detailed investigationon the microscopic scale, it is dficult to speculateon the

19

I

I

reasons for the effectiveness of the spraydrierresidue as a stabtition agent. Figure 1 illustrates

thatthe spraydrier residue was highlyeffkctive at reducing leachablelead concentrationsin the

treatedwastes. In general, the high surface area and the high finenessof we particlesindkate that

this materialhas the potentialto be highlyreactive. This high reactivity,coupled with the small

average particlesize of the residue,may allow the free lime and soluble silicatespresentin this

materialto rapidlycombine with soluble metal species to form insoluble precipitatessuch as

hydroxides, carbonates, and silicates.In additio~ encapsulationof the waste particlesthrough

pozzohmic reactions may physicallyisolate the waste particlesfrom the leachingsolution. Also,

the highalkalinityof this materialcan effectively neutralizethe acidityof the leachingsolutio~

limitingsolubtiion of metal saltsand precipitates.

I?igure 2 illustrates the lead concentrationsfound in the leachatesfrom the treatments

which utilizedthe PFBC material.The PFBC residue produced four treatmentmixtureswhich

passed both the immediateand24 hour TCLP’S. These successfid treatmentswere 50% mixtures

with the munitionssot industrialsoil, wastewater treatmentplantsoil and sandblastwaste.

Mixtures of these four wastes treatedat 10% and 30% dosages fded both ir&e&ate and 24-

hour TCLP’S due to high lead concentrationsin the leachates.ComparingF@re 2 with I@ure 1

shows thatthe PFBC residuewas not as effkctive as the spraydrierresiduein reducing the..

~ leachablelead concentrations of the treatedwastes. Treatmentsof thewsstewater treatmentplant

soil, BOF dust and incineratorashwith the PFBC residue showed littleor no change from the

untreatedlead concentrations, while the other wastes showed decreases of approximatelyone

order of magnitude.The exception was the sandblastwaste which decreased two orders of

20 .,

..

magnitude. Most decreases were only apparentat the highestdosage (500A).

As with the spray drierresidue, most dflerences in meti leachabilitiesbetween the

imme&ate and the 24 hour TCLP’S were minor,with a few exceptions. Mixtuies containingthe

battery sludge fded the 10?? and30% ratiosboth imme&atelyand after 24 hours due to high

lead contents, while the 50V0mixturepassed the immediateTCLP only to fti after24”hours,

againdue to high lead concentrations.Mixtures of the BOF dust and the incineratorashfailed at

all three mixture ratios both imnmdately and after24 hours. Failuresfor the mixturescontaining

the BOF dust were due to highlead concentrations,while those for the incineratorashwere due

to both excess lead and cadmium.

..

The PFBC residue was not as effective as the spraydrier residuein producing successful

treatments.It successfully treatedfour of the seven wastes, althoughit was able to do thisonly at

the highestdosages. In additio~ treatmentsof the batterysludge at the highestdosage only

exceeded the limit for lead by 0.1 mg/1,indicatingthata slightlyhigherdosage may have

successfidly rendered thiswaste non-hazardousW well. The treatmenteff&tiveness of the PFBC

materialcan likely be attributedto the sametypes of mechanismspresentwith the spraydrier

residue, i.e., precipitation as hydroxides, carbonates, sulfates,etc., neutralizationof leachant

acidhy due to alkalinity,and encapsulationthrough pozzolanic reactions. However, sincethe

PFBC residue does not have the same chemical composition as the spraydrierresidue (i.e., free

lime in the PFBC residue is anhydrous,significantMgO is present, and sulfbr is presenthost

exclusively in the sulfite phase) dflerences in the reaction chemistryarevery liiely.

21

Figure 3 illustratesthe lead concentrationsfound in the Ieachatesfrom the treatments

which used the CFBC material.Treatmentswith the CFBC residuewere the leastsuccessfid of

the threeby-products evaluated.There were only two mixtureswhich gave anon-hazardous-..

residue aftertreatment. These two mixtureswere treatmentsof the wastewater treatmentplant

soil at by-product dosages of 30°/0and 50°/0.A mixturecontainingthe munitionssoil treatedat a

50% dosage contained a concentration of lead in the immediateTCLP of 5.6 mg/1,only 0.6 mg/1

over the reWlatory limit for lead. After 24 hours, the concentrationof lead in the TCLP extract of

thismixturewas 4.3 mg/1indicatingthatthe waste had been renderednon-hazardousafterthe 24-

hour mellowing period. A mixtureof the industrialsoil treatedat a 50% mixtureratiopassed the

immediateTCLP with a lead concentration of 0.85 mg/1,but the 24-hour TCLP ffied to confirm

the treatmenteffectiveness with a lead concentrationof 5.4 mg/1.Treatmentsof the battery

sludge,BOF dust and sandblastwaste all contained TCLP lead concentrationswell in excess of

the 5.0 mg/1standardat all threemixtureratios. Treatmentsof the incineratordust contained

concentrationsof both lead and cadmiumin excess of regulatorylimits.

The general ineffectivenessof the CF13Cmaterialas a stabiition agent can most likely

be attributedto its low he lime content. This materialcmtains about 11’% CaO, about half of the

percentageavailablein the other by-products. This materialalso has a low alkalinityas indicated..

by the smallcalcium carbonate equivalency. This smallamountof flee lime may limitthe

formation of lead hydroxide, and the low a.lkrdinilyis most likelyinsufficientto buffer the acidhy

of the leaching solutio~ allowing the finalkxwhatepH to be very low. Lead is amphoteric,and

the solubfity of lead hydroxide reaches a minimumat about pH 9.3. At values below this, the

22 .!

.*

solubtity increases rapidly. Adding additionalIimeto the Cl?BC materialto neutralizethe acidky

of the leaching solution and maintainthe pH close to 9 would likelymake this residuea successfid

treatmentchemical.. .

While the spray drier residuewas effkctive at all dosages, the PFBC materialwas only

effective at the higher dosage of 50°/0. At thisdosage, a significantportion of the treatment

effectiveness can be attributedto simpledilution. In facg given the sameproportion of lead

leacha.bdityin the treated wastes as the raw wastes, treatmentsof the wastewater treatmentplant

soil at the 50°/0dosage could reduce the lead levels below the 5 mg/1TCLP limitby ddution alone.

Therefore, it is debatable whether mixturescontainingthiswaste at 50% dosages can be.

considered treatmentor dflution. Whh the other six wastes, however, some other mechanism

besides dilutionmust occur in order to reduce lead levels below the TCLP limit.

It is important to note that althoughnone of the raw wastes exhibitedtoxkiity

characteristicsfor cadmi~ all of the treatedmixturespreparedwith the incineratordust fded

the TCLP cadmium criteria. k addhio~ in several cases the TCLP lead concentrations of the

treatedwastes were actually higherthan.thoseexhibitedby theraw wastes. This mobtity of lead

and cadmium is most likely attributableto the solubtity changeswhich occurred due to the large. .

change in pH caused during leachingby the highlyalkalineby-products. This mobfity of metal

species is one of the main problems associated with stabilization/solidiication systemswhich rely

heavilyon solubii~” changes for metalcontrol. k manycases, additionaltreatmentchemicals

such as soluble silicates or phosphatesmustbe added in order to effectively control these released

23

metalspecies.

Additional data and detailsof experimentalprotocols utilizedin this investigationmaybe. .

found in the thesis by Pritts8.

CONCLUSIONS

This researchhas shown thatby-products ilolmadvanced flue gas desulfkization systemshave the

potentialto be effkctive stabilizationagentsfor heavy metalcontaminatedhazardouswastes.

While the data presented hereincannot quantitativelydescribe the specific mechanismsresponsible

for metalcontro~ it does presentsome baselineeffectivenessdata.-----

The effiwtiveness of these materialscan be attributedto severalm~hanisms. Perhapsthe

most importantof these is the high amountsof free lime thatthese materialscontainwhich can

limitmetalleachabilitiesby simplepH control. The reductionsin metalleachabiities indicated-in

theseevaluationscannot be attributedsolely to pH contro~ so it is probable thatsoluble metals

arealso being controlled by other mechanisms.These mechanismsmay include precipitationas

various species such as carbonates, silicates,sulfates,etc., inicroencapsuh.tionof the waste..

particlesthrough pozmlanic reactions, and passivationthroughthe formation of metal

precipitates.The high concentration of CaSOqlCaSO~presentin these materials’maypromote the

formation of hyd@ed calcium suko-aluminates(such as ettringite),which may coat the waste

particlescausing decreased contact with the leachant.In additio~ the presence of fly ash in these

24

*.

<

‘

residues provides a source of soluble silicatesnecessaryfor the formation of calcium silicatesand

the subsequentformation of tobermotite gel. While the contributionof cementitiousreactions to

metal control following solidtication is well documented, the overall contributionto metal control

given by these various cementitiouscompounds in the first24-hours aftermixingis not well

known. This is an areawhere additionalresearchneeds to be conducted.

This investigationhas also illustratedsome of the problems associated with the use of

stabilizationas a waste treatmenttechnology. The most apparentproblem is the mobilization of

metal species by the addhion of alkalinetreatmentmaterials. In severalcases, concentrations of

leachablemetalswere higherin the treatedresiduesthanin the raw wastes. Another potential

problem is the l~ge amountof materialrequiredin some instancesto stabii the waste material..... .

The added materialcan significantlyincresse shippingand disposal costs for treatedresidues.

While the success of CCT by-products as waste stabiion agentshas been proven

effixtive at the laboratory scale, theiruse at the commercial scale has seen only limited

application. There are a numberof economic and perceived I.iabiitybarriersto using these

materialscommercially. Perhapsthe greatestbarrierto overcome is the reluctance of utility

operators to allow the use of theirresidualsas treatmentchemicalsfor hazardouswaste due to

potential fhtureliabilityissuesassociatedwith land disposal. Another potentialbarrieris the lack “

of long term data on the stabfition effectiveness of these materials. Waste treatersmaybe

reluctantto use innovativetreatmentchemicalswithout a demonstratedlong-term performance

record. There are also potentialenvironmentalproblems associatedwith final disposal of these

25

,

residuesdue to the high alkalinityand high sulfatecontent. The long-term chemistryof these

systemsare not well understood, but it is expected thatsignificantchanges will occur over time as

the initiallyformed hydratephases change to more thermodynamicallystablephases. In addhio~.-

expansivesuKatescan forq which will cause breakdown of the solidtied matrixpossibly

exposing previously isolated waste particlesto the environment.

Despite these shortcomings, these materialsdo have meritas treatmentchemicals. They

are effective in some applications,can be cheap to obtain along establishedshippingroutes,

theiravailabilitywill likely increaseas more advanced CCT systemsare places into se~ce.

and

Data describing the abilityof CCT materialsto control metalsthrough solidtication-----

reactionsis not presented here, but the literatureholds severalcitationsdescribingthe abilityof

these materialsto enter into pozzolanic reactions’. This studyhas shown the applicabilityof CCT

by-products as treatmentchemicals,however continued researchin thisarea is needed to better

describe the various reactions which occur in these systemsso thatthe behavior of stabiied

wastes after finaldisposal can be understood.

ACKNOWLEDGMENTS..

Data for thismanuscriptwas obtainedduringwork on the United St.rtesDepartmentof Energy

researchproject ‘at the Universityof Pittsburghentitled“Treatmentof Metal-Laden Hazardous

Wastes with Advanced Clean-Coal-Technology By-Productsfl award#DE-FC21-94MC31175.

26 .,

.*

..

The authorsacknowledge the cooperation of the USDOE Office of Fossil Energy, Morganto~

West V@inia. Data collection was a collaboration between various resources. University

participantsincluded the Universityof PittsburghSchool of Engineering,Civil andEnvironmental

EngineeringDepartment and the ChemicalEngineeringDepartment.Industrialparticipants

included Dravo Lime Co. andMax Environmental,Inc., both of Pittsburgh PA.

REFERENCES

1.

2.

3.

4.

Conner, Jesse R. Chemical Fixzrtionand Solid@ation of H~ardw Wmteq Van

Nostrand Reinhold: New Yo& 1990; p 21.

.... .

Bee@y, J. H.; Bingaq J. In Dry, CalciumBasedFGD By-Products as

StabilizutiowS’olidi~cationAgen@; Proceedings of the Third InternationalSymposiumon

Stabilization/Solidificationof Hazardous, Radioactive, and Mixed Wasteq Williamsburg

VA 1993,’ p. 2.

Kosmatk~ Steven H.; Panarese,Wfiarn C.; Dw”gn and Control of Concrete Mixturw,

PortlandCement Association Skokie, IIlinois,1988; p 15.

Treatability StudjMmal Soli@jicationAStabiIizatioqThe PQ corporation Valley

Forge, P.& p 5.

27

5. FederalRegister, Volume 55, Number 61, March 20, 1990, p 5.

6. TestMethods for Evaluating Solid Wrote:LuboratoryA6nua( PhyshxzUChemical

Methti, Office of Solid Waste: U.S. EnvironmentalProtection Agency. U.S.

Government PrintingOffice: Washin@oXZDC, 1986; EPA SW-846.

7. American Society for Teti”ng andMaterials, Annual Book of AS2’MStana?izr&,American

Society for Testing andMaterials.Philadelphi~PA 1990.

8. Pritts, Jesse TV.; Stabilizationand Solidi@tion ofMetaUuden Hhzardous Wmtes with

Clean-Coal-Technology By-Prodhc@, M.S. Thesis, Universityof Pittsbur& Dec. 1996.----- -

ABOUT THE AUTHORS

JessePrittsis a Cifi Engineerwith the United StatesEnvironmentalProtection Agency. This

manuscriptwas prepared with data and tiormation collected duringhis graduateresearchin the

Departmentof (Ml and EnvironmentalEngineeringat the.Universityof Pittsburgh.His current

work at EPA focuses on various issues relatedto the control of urbanwet weather discharges.. .

Dr. Ronald D. Neufeld is a Professor of CMl Engineeringtithe Departmentof CMl &d

EnvironmentalEngineering at the Universityof Pittsburgh.Dr. JamesT. Cobb, Jr. is anAssociate. .

Professor of Chemical Engineeringin the Departmentof ChemicalandPetroleum Engineeringat

theUniversityof Pittsburgh.JessePrittscan be reached at USEP~ Engineeringand Analysis

<#

28 ,.

? .

Division (4303), 401 M. Street SW, Washingto~ DC 20460, or by phone at (202)260-7191.

DISCIA.IMER

Any ideas, opinions, conclusions, or recommendations expressed hereinare solely those of the

authors, and do not necessarilyexpress the ideas of the United StatesEnvironmentalProtection

Agency, the United StatesDepartmentof Energy, or the United States.

.

..

29

Table 1. Hazardous wastes treated with CCT by-products.

Waste SourceBatteryMfg. Sludge Wastewater treatmentplantsludge generatedfrom treatingwastewater

from the production of lead acid storage batteries.MunitionsSoil Contaminatedsoil from a munitionsdepot where’kad-containing

munitionswere stored.IndustrialSoil Contaminatedsoil from a city multi-useindustrialsite.WWT’P Soil Contaminatedsoil from sewage dryingbeds from a former hospital

wastewater treatmentplant site.BOF Dust Baghouse dust from a basic oxygen fimnacesteehnakingfacility.IncineratorDust Fly ashcollected by an electrostatic precipitatorat a municipalwaste

incinerator.SandblastWaste Sandblastwaste containingsilicasan~ lead-based paintchips andwood

particlesfrom a buildiig rehabilitationproject.

. .

30

..

...-.

,.

Table 2. Metals regulated under the Toxicity Characteristic.

EPA HW No.” Constituent ChroNc Toxicity RegulatoryReference Level (mg/1) Level (m@l)

D004 . . . . . . . . . . . . . .. Arsenic . . . . . . . . . . . . . . . ...0.05 . . . . ...-.............5.0D005 . . . . . . . . . . . . . .. Barium . . . . . . . . . . . . . . . ...1.0 . . . . . ..~ .’ . . . . . . . . . . 100.0D006-. .. - . . . ..- . . .. Cadmium . . . . . . . . . . . . . ...0.01 . . . . . . . . . . . . . . . . . ...1.0D022 . . . . . . . . . . . . . .. Chromium . . . . . . . . . . . . . ...0.05 . . . . . . . . . . . . . . ..-~. .5.OD008 . . . . . . . . . . . . . .. Lead . . . . . . . . . . . . . . . . . ...0.05 . ...-.......-.......5.0DOOM. . . . . . . . . . . . . . . Mercury . . . . . . . . . . . . . . ...0.002 . .-..........-.....0.2DOIO . . .. - . . . .. -.-. .Selenium . . . . . . . . . . . . -....0.01 . . . . . . . . ...-........1.0DO1l . . . . . . . . . . . . . .. Silver . . . . . . . . . . . . . . . . ...0.05 . . . ...-.............5.0-dous waste number.

.. .

●

✎

Table 4.Gee-chemical analysisof CCT by-products.

Parameter,VO(wthvt) SprayDrier Residue PFBC Residue CFBC ResidueCaO . . . . . . . . . . . . . . . . . . . . . . . ..25.4l . . . . . . . . . . . 22.13 . . . . . . . . . . . ...-11.06MgO . . . . . . . . . . . . . . . . . . . . . . . .. O.7O . . . . . . . . . ..14.38 . . .._. -. . . . . . . . . ..l.36SiOz . . . . . . . . . . . . . . . . . . . . . . ...22.33 . . . . . . . . . .. 19.93 . . . . . . . . . . . . ...46.64F~O~ . . . . . . . . . . . . . . . . . . . . . . . ..6.23 . . . . . . - . . . . . 9.02 . . . . . . . . . . . . ...-7.08A1203. ..11 . . . . . . . . . . . . . . . . . ..ll.40 . . . . . . . . . . ..7.75 . . . . . . . . . . . . . ..”17.95COZ . . . . . . . . . . . . . . . . . . . . . . . ...3.58 . . . . . . . . . .. 12.57 . . . . . . . . . . . . . ...0.70Total Sulfbr@ S . . . . . . . . . . . . . . ..9.62 . . . . . . . . . . . . 4.59 . . . . . . . . . . . . . ...2.37SulfateSulfbr@ SO~ . . . . . . ..-. .-. l.79 . . . . -- . . . . . 10.60 . . . . . . . . . . . . . ...5-46SuffiteSulfir@ SOz . . . - . . . . .-..17.79 . . . . . . . . . . . - 0.69 . . . . . . . . . . . ...-.0.37LOI@600°C . . . . . . . . . . . . .-..-3.17 . . . . . . .. Not Analyzed . . . . . . . . Not AnalyzedLOI@/llOO°C . . . . . . . . . . . . . . . .14.68 . . . . . . . . . . . 13.54 . . . . . . . . . . . . . ...4.16

....

Table 5.Reactivity and acid neutraltilon analysisof CCT by-products.

Parameter SprayDrier Residue PFBC Residue CFBC ResidueTemperatureRise, IF . . . . . . . . . . . 2* . . . . . . . . . . . . . . . . ..5*..... . . . . . . ...8*Calcium Carbonate .

Equivalency, %CaCOq . . . . . . . ...42.5 . . . . . . . . . . . . . . . . 53.4 . . . . . . . . . . . ..” 12.9Available LimeIndex %CaO .pH(soil) . . . .

. . . . . . . . . . . . . . . . 3.2 . . . . . . . . . . . . . . . . . 1.0 . . . . . . . . . . ...4.4

. . . . . . . . . . . . 12.36 @26°C - . . . . . ..ll.92@25°C . . . . . 12.52 @22°CMixed Ratio,lbs/gal . . . . . . . . ..-. 13* . . . . . . ..- . . . . . . ..20* . . . . . . . . . . . . . 16-*Average of several samples.

.... .

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Table 6.Physical properties of CCT by-products.

\Parameter SprayDrier Residue PFBCResidue CFBC ResidueSpecific Gravity,g/cc . . . . . . . . . . . . . . . . . 2.,40 . . . . . . . . . . . 2.88 . . . . . . . . . . . ..2.68Bulk Density (loose),lbKl?.. . . . . . . . . . . . 35 . . . . . . . . . . . 64...,,.........58Bulk Density (tamped),lb/ft? . . . . . . . . . . . 42 . . . . . . . . . . . 70 . . . . . . . . . . . ...66BlaineFineness,cm2/gm . . . . . . . . . . . . . 13..190 . . . . . . . . . 5,610 . . . . . . . . . . . 7,410‘/OPassing200mesh... . . . . . . . . . . . . . . 96 . . . . . . . . . . . 92 . . . . . . . . . . . ...46‘/OPassing325mesh... . . . . . . . . . . . . . . 83 . . . . . . . . . . . 85...........-..37Specific SurfaceAr~ m21gm. . . . . . - . . . . 6.57 . . . . . . . - . -.2.65... . . . . . . . ...9.41Particle Size Distribution:Passing 80mes~ % . . . . . . . . ..- . . . . . . . 99.6 . . . . . . . ..-.94.0- . . . . . . . . . ...48.910%passing, micron . . . . . . . . . . . . . . . . . 11.66 . . . . . . . . . .2.87 . . . . . . . . . ...3.5050%passin~ micron. . . . . . .. . . . . . . . . . . 4.61 . . . . . . . . . 13.39............29.4290°Apassin~ micron . . . . . . . . . . . . . . . . 32.90 --------- 58.33...........124.30AveragePzuticle Size,micron . . . . . . . . . 11.59 . . . . . . . . . 23.60 . . . . . . . . . ...48.04

.. . .

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Table 7. Total and TCLP metalsconcentrationsof hazardouswastes.

Waste TypeBattery Munitions Industrial BOF Incinerator WWTP Sand-Sludge Soil soil Dust ~ Dust. soil Blast

WasteArsenic

Total (mg/kg) . . . ..<20 . . ..<20 . . . ..<20. .-. <20.... 84 . . . .. QOO. . ..QOTCLP(mg/1) . . . ..<O.l . . .. <0.1 . . . <0.1 . . .. <0.1 . . ..0.2.... <0.1 . . .. <0.1

BariumTotal (mg/kg) . . . . ..13 . . . ..130 . . . . .130.....34.....550.....84. . ...60TCLP(mg/1) . . . . .. <5..... <5 . . . ..<5 .-. .-. ~5 . . . . . <5 . . . ..<5 . . . ..<5

CadmiumTotal (mg/kg) . . . . . . 3 . . ...4.8... ..5.4 . . . ..55 . . . ..630 . . . .. <2. . ...2TCLP(mg/1) . . ..-0.19 . . .. <0.1 . . . <0.1 . . ..<O.l . . .. <0.1 . . . <0.1 . . .. <0.1

ChromiumTotal (mg/kg) . . . . ..122 . . . ..59 . . ...22 .-. . 260 . ...130-....8.7.....9.2TCLP(mg/1) . . . ..<O.l . . .. <0.1 . . . <0.1 . . ..<O.l . . .. <0.1 . . . <0.1 . . .. <0.1

LeadTotal (rng/kg) . . . ..31200 . ..1200. . . 5000 . . . 1400 . . . .5700 . ...750... 43000TCLP(mg/1) . . . . . . 20 . . . . . .26 . . ...80 . . . ..14..... 20.....7.8....350

Mercury.... .

Total (mg/kg) . . . .. 0.12 . . .. 0.2 . . . . . 3.2 . . . . ..0.3 . . ..4.7.... 0.36....0.19TCLP(mg/1) . . . .. <0.01 . . <0.01...<0.01 . ..<O.O1 . . . <0.01 . .. <0.01 . ..<0.01

SeleniumTotal (mg/kg) . . . ..<<02 . . ..<O.2. . . <0.2 ..-. <0.2 . . ...85.... 0.36....0.26TCLP(mg/1) . . . ..<O.l . . .. <0.1 . . . <0.1 . . ..<O.l . . .. <0.1 . . . <0.1 . . .. <0.1

SilverTotal (mgfkg) . . . ...62.....3.6.. . ..~- . . ..<9 . . ..-6.9 . . . ..~ . . . ..~2TCLP(@l) . . . ..<O.l . . .. <0.1 . . . <0.1 . . ..<O.l . . .. <0.1 . . . <0.1 . . .. <0.1

+.

Table S. Total and TCLP metals concentrations of flue gas desulfbrization by-produots.

By-Product SourceSprayIDrier PFBC CFBC

ArsenicTotal (mglkg) . . . . . . . . . . . . . . . . . . . . 41 . . . . . . . . . . . ..140 ..~~” . . . . . . . ...95TCLP(mg/1) . . . . . . . . . . . . . . . . . . . <0.1 . . . . . . . . . . . .. <0.1 . . . . . . . . . . ...0.9

BariumTotal (mgkg). . . . . . . . . . . . . . . . . ...97 . . . . . . . . . ..~ . 150 . . . . . . . . . . . . . 160TCLP(mg/1) . . . . . .. - . . . . . . . . . . ..<5 . . . . . . . . . . . . . <5 . . . . . . . . . . . . ..<5

CadmiumTotal (mgkg). . . . . . . . . . . . . . . . . . . . 6.6 . . . . . . . . . . ...4.8... . . . . . . . ...10.0TCLP(mg/1) . . . . . . . . . . . . . . . . . . . <0.1 . . . . . . . . . . . ..<0.1 . . . . . . . . . . ..<0.1

ChromiumTotal (m#kg). . . . . . . . . . . . . . . . . ...29 . . . . . . . . . . . . . 15 .- . . . . . . . ..=..50TCLP(mg/1) . . . . . . . . . . . . . . . . . . . <0..1 . . . . . . . . . . . ..<0.1 . . . . . . . . . . ..<0.1

LeadTotal(mgkg) . . . . . . . . . . . . . . . . . . . . 3.0 . . . . . . . . . . ...4.6... . . . . . . . . ...3.6TCLP(mgll) . . . . . . . . . . . . . . . . ..- <0.1. . . . . . . . . . . ..<0.1 . . . . . . . . . . ..<0.1

MercuryTotal(mg/kg) . . . . . . . . . . . . . . . . . . .. 0.6. . . . . . . . . . . ..<0.1 . . . . . . . . . . ...1.1TCLP(mg/1) . . . . . . . . . . . . . . . . . .. <0.01 . . . . .._.---..O1..<O.Ol. ..- . . . . . . ..<O.Ol

SeleniumTotal(mglkg) . . . . . . . . . . . . . . . . . . . <0.2 . . . . . . . . . . . ..<0.2 . . . . . . . ..-. .<0.2TCLP(mg/i) . . . . . . . . . . . . . . . . . . . <0.1 . . . . . . . . . . . ..<0.1 . ..- . . . . . . . ..<0.1

SilverTotal(mg/kg) . . . . . . . . . . . . . . . . . . ..<2 . . . . . . . . . . . . . <2 . . . . . . . . . . . . ..-QTCLP(mg/1) . . . . . . . . . . . . . . . . . . . <0.1 . . . . . . . . . . . ..<0.1 . . . . . . . . . . ..<0.1

..

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Table 9. Success of by-product/waste combkations”.

Waste

BatterySludge

Munitionssoil

Industrialsoil

BOF Dust

IncineratorDust

WwTP soil

SandblastWaste

Mixtureswhi

By-Product II SprayDrierII

PFBC.-II

CFBCSource I

establishedregulatory levels, andtherefore have been render~ non-hazardous are indicatedwithand X’.

,

Table 10. Metals concentrations of treatedwwtes.*

Cadmium (mgh) Lead (mg/1)Imme&ate 24-hours Imrnedate 24-hours

Dosage: 10% 30’% 5070 10’% 30% 50% 10’% 3070 SO*O 10’% 30V0 50%Treatments w/ Spray Drier Residue

Battery Sludge <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 0.14 0.28 0.19 0.15 0.21 0.21Munitions Soil <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 0.37 0.41 0.28 0.41 0.35 0.28IndustrialSoil <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 0.54 0.54 0.37 0.15 0.26 0.21BOF Dust -=0.1 <0.1 <0.1 <0.1 -=0.1 <0.1 1.5 ~ 6Q~~4.3IncineratorDust 22.0 13.0 &JJ 24.0 14.0 N 1.3 0.46 0.26 1.6 0.45 0.27WWTP Soil <().1 <().1 <0.1 <0.1 <0.1 <0.1 0.39 0.57 0.46 0.47 0.56 0.55SandblastWaste <0.1 <0.1 <0.1 <0.1 ~0.1 <0.1 0.38 0.15 0.13 0.44 0.13 0.11

Treatments w/ PFBC ResidueBatterySludge 0.19 0.15 <0.1 0.18 0.14 <0.1 fim4.lQ8’ti~MunitionsSoil <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 .10.O 13.0 1.2 16.0 23.0 0.34IndustrialSoil <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 ~ m 1.7 17.0 22.0 1.6BOF Dust -=0.1 -=0.1 <0.1 <0.1 -=0.1 <0.1 ~o.o 14.0 13.0 19.0’” 15.0 ~IncineratorDust Z5.O 18.0 14.0 30.0 17.0 13.0 16.0 17.0 U 13.0 16.0 uWwTP soil <().1 <0.1 <0.1 <0-1 <0.1 <0.1 --~ ~ 2.3 23.0 11.0 2.1SandblastWaste <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 m U 2.0 210 21.0. 0.49

...

Treatments w/ CF’BC Residue

Batte~ Sludge 0.15 0.13 <0.1 0.15 0.12 <0.1 ~ 46.0 13.0 15.0 11.0 wMunitions Soil <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 34.0 17.0 X u M 4.3Industrial soil <(). 1 <0.1 <0.1 <0.1 <0.1 <0.1 17.0 14.0 0.85 ~ ~ ~

130F Dust <().1 <0.1 <0.1 <().1 <0.1 <0.1 ~2.O 16.0 13.0 20.0 14.0 U

IncineratorDust Z2.O 18.0 15,0 22.0 17.0 14.0 12.0 20.0 13.0 22.0 22.0 24.0WwTP soil <().1 <().1 <().1 <().1 <().1 <().1 4.9 4.6 0.31 w <0.1 1.18SandblastWaste <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 ML) W ~ W 67=

*Values in underlinedbold type exceed currentTCLP limits.

.

Figure 1. Lead concentrations in immediate TCLP leachates of wastes treated with spray drierresidue.

1000

0.1

.’

Lwin- MuN ND W@fp BOF “--iNC- sAtKl

Waste Soume*

13131Untreated

ZIIO% D-3

E3 30% Dose

N 50% 60s3

. . TCLP Limit(5 mgfl)

T3ATEl%ttety Studgq MUN=MintionaS@ IN)=hduatrialS@ VWVTWMS tewaterTreatrnwtFlantMBOF== hi+ NC=lnciieratorR@ SANO=SandblastVVaSte .

Figure 2. Lead concentrations in immediate TCLP leachates of wastes treated with PFBCresidue.

. .

1000

100

10

1

0.1BA7T MUN ND VWWI’ BOF ----NC” SAN)

Waste Source’

= Untreated

m 10% Do=

= 30% Dose

m 50% Dose

. . TCLP Limit(5 mg/1)

%AIT=Battery Sludgq MIJN=MunitionsBo~ N2=lndustrislsot VWVIP=WsstewsterTrestm?ntFlsntSoilBY-B(X CkIs~INC=hciieratorDL@ SNO=SsndblsstWaste

..

.

Figure 3. Lead concentrations in immediate TCLP leachates of wastes treated with CFBCresidue.

uco.!2

1000

100

10

1

0.1

EEllUntreated

m 10% Ooae

E=i30% Dose

m 50% Dose

.- TCLP Limit(5 mgll)

BAIT MUN IND WATP BOF ‘- INc SAW

Waste Source*%AIT=BatteIY Sludgq MIIWtlunitionsSoit N3=hdustrialSoit W&VllWVastewaterTreatmentI%@ Sod

BOF=BOFCus~INC=IncineratorCIJstSAND=SandblastWaste

..

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.

APPENDIX B

AN EVALUATION OF THELONG-TERM LEACHING CHARACTERISTICS OF

METALS FROM SOLIDIFIED/STABILIZED WASTES

-.

55

AN EVALUATION OF THE LONG-TERM LEACHING CHARACTERISTICS OF

MfnALs FROIId solidified/stabilized WASTt3

by-.~~,/

Jana Maria Agostini.-\

B.S. in Chemical Engineering, University of Pittsburgh, 1996

.... ,., \

Submitted to the Graduate Faculty

of the School of Engineering

in partial fulfillment of

the-requirements for the degree of

Master of Science

in

Civil and Environmental Engineering

University of Pittsburgh

1998

The author grants permissionto reproduce copies.

Signed

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COMMIITEE SfGNATURE PAGE

Ronald D. Neufeld, Ph. D., P.E.Advisor Signature

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ACKNOWLEDGMENTS

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The treated waste samples for this study were obtained from prior work

conducted on the United States Department of Energy research project at the

University of Pittsburgh entitled “Treatment of Metal-Laden Hazardous Wastes with

Advanced Clean-Coal Technology By4%oducts,” award #DE-FC21-94MC31 175.

The author..acknowledges the cooperation of the USDOE, Office of Fossil Energy,

Morgantown Energy Technology Center, Morgantown, West Vtrginia.

My app(eciqtion.goes to.Dr. Ronald Neufeld, research and academic advisor,

who provided opportunity, direction and support during the completion of this

project. In addition, thanks to Dr. James Cobb, who allowed me to become involved

with this project during my undergraduate education and who has provided helpful

support. I would also like to thank the University of Pittsburgh Department of Civil

and Environmental Engineering personnel for their support and for the use of its

laboratory facilities.

In addition to Universi~- of Pittsburgh faculty and staff, I would like to thank

several of my fellow graduate students from the Departments of Civil and

Environmental Engineering and Chemical Engineering. Special thanks to Vourneen

Clifford and Jesse Pritts for their previous work which laid the foundation for my

project, and for their friendship.

Special thanks to my supervisors, colleagues and friends at RETEC, Inc. who

have allowed me to finish this project and work part-time. The patience you have

all shown is greatly appreciated. In addition, I would like to thank Dr. Ingrid Klich,

whose guidance and support greatly aided in the completion of this project.

This section would not be complete without the mention of my parents, my

brothers, my grandmother and my fiance. My deepest gratitude goes to my family,

who have supported me in every way with their guidance, encouragement and love.

...Ill

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ABSTRACT

:\\ Signature

,. Ronald D. Neufeld, Ph.D....i % \

AN EVALUATION OF THE LONG-TERM LEACHING CHARACTERISTICS OFMETALS FROM SOLIDIFIED/STABILIZED WASTES

Jarna M. Agostini, M.S.

University of Pittsburgh._

Current hazardous waste treatment standards are based on the premise that

the leaching properties of stabilized/solidified (s/s) wastes do not significantly

change with time. However, numerous studies have examined the mineralogical

changes which occur in s/s wastes with time. Changes in the mineralogy of the s/s

matrix could cause changes in the microstructure, which may influence the

leachability of hazardous constituents in

research was to evaluate the long-term

the s/s matrix. The objective of this

leaching characteristics of s/s waste

samples (originally prepared during a prior research project at the University of

Pittsburgh) by analyzing the available s/s waste samples; and to support such

results with a review of the literature in this area. Six s/s waste samples, remaining

iv

from the previous study, were examined to evaluate changes in the leachability of

cadmium, chromium, lead and zinc as a result of aging. In order to measure

changes, the six original s/s waste samples were retested using the Toxicity

Characteristic Leaching Procedure (TCLP) and the Shake Extraction Test (ASTM.

D 3987-85) after two years of curing< Cadmium, as measured in the TCLP.-\

Ieachates of the six samples, remained immobilized after two years, as expected,.

based on the ~tera.ture~eview.. Chromium also remained tightly bound within the s/s

matrix after two years, in agreement with previously published results. The

leachability of lead from the s/s matrices varied among the six samples after two

years of curing. This result is expected based on the noted mechanisms for lead

immobilization found in the literature. Similar to lead, the concentration of zinc in

the TCLP leachates of the twcryear old samples varied. The varying results for zinc

stabilization may be expected according to the mechanisms described for zinc

immobilization presented in the literature. In addition, the shake extraction test

Ieachates contained lesser concentrations of cadmium, chromium, lead and zinc

than did the TCLP Ieachates for each of the six s/s wastes examined. This result

is expected since the shake extraction test uses a less aggressive extraction fluid

(near neutral pH) than does the TCLP.

7I L

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1 DESCRIPTORS

IChemisorption

I Encapsulation

I Hazardous waste:\

Immobilization. .

I Precipitation”, ... ..

I Solidification

Clean Coal Technologies

Fly ash

;;?,/’

Heavy metals ~

isomorphic substitution

Shake Extraction Test

Stabilization

Waste TreatmentToxicity Characteristic Leaching Procedure

./;-:::

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TABLE OF CONTENTS

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Page

ACKNO~EDGMENTS ...................................................................................... iii

ABSTRACT ......................................................................................................... iv.

LIST OF FIGURES .............................~.<. ............................................................. X

LIST OF TABLES .....~ ......................................................................................... xi. .

NOMENCLATURE ................................................................................................. xii

1.0 lNTRODUCTIO'N .........................................................................................l

2.0 BACKGROUND AND LITERATURE REVIEW ...........................................4

2.4

2.2

2.3

2.4

2.5

Stabilization/Solidification Technology Overview .............................4

2.1.1 Inorganic Processes ..............................................................5

2.1.2 Choosing-the Best Stabilization/SolidificationSystemfora Waste ...........................................................................6

Regulatory Background ...................................................................8

Basic Cement Chemistry as Applied in Stabilization/SolidificationProcesses ........................................................................................9

Mechanisms of Stabilization ..........................................................l2

2.4.1

2.4.2

2.4.3

2.4.4

2.4.5

Encapsulation .....................................................................l2

Isomorphic Substitution .......................................................l4

Precipitation ........................................................................l5

Redox Potential ...................................................................18

Chemiso~tion .....................................................................2l

Immobilization of Metals in Stabilized/Solidified Wastes ...............22

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2.5.1 Cadmium .............................................................................23

2.5.2 Chromium ...........................................................................25

2.5.3 Lead ....................................................................................26.;,:/

2.5.4 Zinc ~27......................................................................................-Y

2.6 ‘ Metals Leachability as a Function of pH ........................................27,.

2.7 Long-Te~m Performance of Stabilized/Solidified Wastes ..............29

2.7.1

2.7.2

2.7.3

Methods for Analysis of Long-Term Performanceof Stabilized/Solidified Wastes ............................................29

Simulated Long-Term Performance Study Results .............3l

Long-Term Performance Study Results ...............................32

3.0 PRIOR RESEARCH AT THE UNIVERSITY OF PITTSBURGH ANDORIGINAL SAMPLE ~EPAWTION ......................................................35

3.1 Prior Research at the University of Pittsburgh ...............................35

3.2 Original Sample Preparation ..........................................................36

3.2.1

3.2.2

3.2.3

Stabilization/Solidification Agents .......................................36

Hazardous Waste Materials ................................................37

Treated Waste MiMures ......................................................38

4.0 EXPERIMENTAL METHODS ...................................................................39

4.1 Leaching Tests ...............................................................................39

4.1.1 Toxicity Characteristic Leaching Procedure (TCLP) ...........39

4.1.2 Shake Extraction Test .........................................................40

4.2 Analytical Procedures and Techniques ..........................................4O

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4.2.1 Sample Grinding/Preparation ..............................................4O

4.2.2 Digestion Procedure ............................................................4l

4.2.3 Flame Atomic Adsorption (FLAA) Spectroscopy .................4l.

4.3 Quality Assurance/Quaift$ Control (QA/QC) Methods ...................42

5.0 RE’&JLTS AND DISCUSSION .................................................................43. .

5.1 ,Lea~hing Test Results ...................................................................43

5.1.1 Cadmium .............................................................................43

5.1.2 Chromium ...........................................................................44

5.1.3 Lead ....................................................................................45

5.1.4 Zinc .....................................................................................49

6.0 SUMMARY AND Conclusions ...........................................................53

7.0 SUGGESTIONS FOR FUTURE RES~RCH ..........................................55

APPENDIX

APPENDIX

APPENDIX

APPENDIX

A CLEAN-COAL TECHNOLOGY BY-PRODUCTS ................57

B ORIGINAL DATA ................................................................6l

c USING THE PERKIN-ELMER 1IOOBAA SPECTROPHOTOMETER ............................................67

D QA PROJECT PLAN FOR “TREATMENT OFMETAL-lADEN HAZARDOUS WASTES WITHADVANCED CLEAN-COAL TECHNOLOGYBY-PRODUCTS” .................................................................74

BIBLIOGWPHY ................................................................................................ 93

REFERENCES NOT CITED .............................................................................lOO

ix

LIST OF FIGURES

Figure No. Page

1 Solubilities of Metal Hydroxides as a Function of pH ....................16

2 Eh-pl-i Diagram for Pati of the Cr-O-H System ..............................l9<+ [’

3 Eh-pH Diagram for Cadmium ........................................................2O.. ‘\

4 ‘ A Summary of Models for the Interaction of PriorityMetal Pollu~ants with Cement ..............................................23

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5“ Lead Co~centra~cm versus Time for TCLP Extracts ......................47

6 Lead Concentration versus Time for Shake ExtractionTest Extracts ..................................................................................48

7 Zinc Concentration versus Time for TCLP Extracts .......................5l

8 Zinc Concentration versus Time for Shake ExtractionTest Extracts ..................................................................................52

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Table No.

Al

BI

B2

B3

B4

B5

B6

B7

LIST OF TABLES

Page

Mean Comparison of CCT By-Product Properties .........................66

TCLP Extracts - Cadmium Analysis ...............................................68<

TCLP Extracts .Chrotifi&A nalysis . .............................................69:\

~ TCLP Extracts - Lead Analysis ......................................................7O

“$h~ke E@ractio.nTest - Lead Analysis ..........................................70

TCLP Ektracts - Zinc Analysis .......................................................71

Shake Extraction Test - ~nc Analysis ...........................................7l

TCLP Leachate Metal Concentration versusTCLP Leachate pH ........................................................................72

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NOMENCLATURE

The following is a listing of the various chemical compounds and mineral speciesdiscussed throughout this document.

Common Name Cement Chemistry Chemical FormulaNotation

Tricalcium silicate (alite)-\

Dicalcium silicate (belite). .

Tricalcium alti~inate . .

Tetracalcium aluminoferrite

Calcium silicate hydrate(tobermorite gel)

Calcium aluminoferrite hydrate

Tetracalcium aluminate hydrate. _

Ettringite

Calcium sulfate (anhydrite)

Calcium carbonate

Anhydrous lime (quicklime)

Hydrated lime (portlandite)

c31t “ 3CaO”SiOz

CJ4 2CaO”SiOz

C,A 3CaO”Alz0,

CdAF 4Cao”AlzO~”FezO~

3CaO”2Si02”3H20

3Ca0.A120~-FezO~. 12HZ0

3Ca0.AlzOa.Ca(OH)z”12H20

3Ca0.A120,.3CaS0,.32~0

CaSOd

CaCO~

CaO

Ca(OH)2

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i 1.0 INTRODUCTION

I)

Stabilization/Solidification (S/S) processes are effective in treating a variety

of waste materials ~forreuse or disposal. According to the US EPA, stabilization;;?/

refers to those technologies that reduce the hazardous potential of a waste by‘\

converting ‘the contaminants into their least soluble, mobile, or toxic form.. .>

I Solidification techniques are those which enc&ipsulatethe waste in a monolithic solid

I of high structural integrity.(lY The standard bulk material handling and mixing

equipment used in many s/s processes make the technology appear simple.

.-.1However, significant challenges arise when s/s processes are applied. The

I morphology and chemistry of s/s treated wastes are complex and, as yet, not well

understood.-.

IS/S is frequently the technology of choice for the treatment of soils and

! sludges containing one or more metal contaminants. According to current

regulations regarding hazardous wastes promulgated by the US EPA,

.Istabilization/solidification processes have been identified as the Best Demonstrated

I Available Technology (BDAT) for a variety of listed waste codes.(z) Presently, the

environmental acceptability of a hazardous waste is based upon the US EPAsIExtraction Procedure Toxicity Test (EP Tox) or the Toxicity Characteristic Leaching

.i Procedure (TCLP). A treated waste is deemed stable if the EP Tox or TCLP

*Parenthetical references placed superior to the line of text refer to thebibliography.

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Ieachate derived from it contains constituents in concentrations

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below the

maximum contaminant levels (MCLS) stated in the regulation. However, the

question of whether the immobilized constituents remain immobilized with the

passage of time is hot well defined.;,>?/

in order to -determine the successful long-term performance of a

solidification/stabilization (s/s) process, many types of analyses, including physical

tests, leaching ahd extraction tests, chemical tests, biological tests and micro-

characterizations may be required. Currently, no one test or procedure can be

performed to determine the long-term performance of a s/s waste. Most often, a

combination of several tests is needed to gather information about the chemistry

and mineralogy of the treated waste.

As a basis for this study, six treated waste samples, which were developed

through a previous research project at the University of Pittsburgh (1995), were

analyzed using two different extraction procedures, the TCLP and the Shake.

Extraction Test (ASTM D 3987435). For the original research project, three different

lime-containing Clean Coal”Technology (CCT) fly ash by-products were used as the

s/s binders to treat seven different types of metal-laden hazardous wastes. As a

result of the previous research, many of the binder/waste mixtures passed the TCLP

and were deemed stabilized according to regulations. For this project, six of the

original s/s treated wastes, which initially passed the TCLP, were re-examined after

two years curing time to determine if the leachability of metals from the treated

waste had changed. In addition, the shake extraction test was performed on the

3

samples in order to accumulate more information about the leachability of metals

from the treated waste samples.

Though other methods have been used to determine the long-term

performance of s/s &astes, the TCLP and Shake Extraction Test were used for this;,?/

study for the reasons discussed below... -%

● ‘ The previous research project at the University of Pittsburgh, from

“whichthe samples for this study were taken, used the above listed

extraction procedures. For reasons of consistency, these procedures

were repeated in this study.

● As discussed in Section 2.7.2 and 2.7.3 of this document, the

repetition of the TCLP on s/s wastes, after several years of curing,

has been used h several other long-term performance studies.

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BACKGROUND AND LITERATURE REVIEW

2.1 Solidification/StabilizationTechnologyOvewiew

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“Stabilization/solidification is normally a two step treatment process in which

the waste is’initiallychemically stabilized, to concentrate the hazardous components. .

in the waste into an insoluble form. Solidification occurs, due to a second set of.“

chemical reactions initiated by the addition of cementitious additives to the stabilized

waste.’’(3) In order to assure an adequate level of performance, it is essential to

understand the two key processes which are fundamental to the production of an

environmentally acceptable waste. The first process is the method for producing

a solid material, since this-is--essential for solidification. The second process is

responsible for the containment of the hazardous constituents of the waste within

the microstructure of the solidified material.(4) However, it should be noted that a

material need not be solidified in order to achieve stabilization of hazardous

constituents.

Containment of hazardous components is the most important characteristic

of solidified wastes, and has

chemically simple systems.

been extensively investigated, particularly for

Studies indicate that a number of retention

mechanisms operate, but it is not clear whether these make a significant

contribution to metal containment in commercially produced solidified materials.(5)

Stabilization/solidification technologies can be broadly categorized as either

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inorganic or organic systems, based on the nature of the solidification chemicals

used, not the waste composition. Inorganic systems are used for the chemical

fixation and solidification of complex wastes in order to produce a nontoxic,

environmentally safe product that can be used as landfill material. These processes~~/’

use inorganic reagents which react with certain waste components and ‘with.. ‘\

themselves’to form chemically and mechanically stable products. Organic systems. .

are not often+.used for industrial wastes except in the area of radioactive waste

solidification. These systems are sometimes hydrophobic in nature and therefore

create difficulty when mixed with water based wastes.(s)

2.1.1 Inorganic Processes

Inorganic processes

..

are generally grouped into two categories: those that

use bulking agents, such as fly ash, and those that do not. Bulking agents are

those materials which, when added to the mixture, add to the total solids and

viscosity of the waste. These bulking agents may prevent the settling out of the

suspended waste components before solidification can occur and/or help produce

a solid with better physical properties. Bulking agents may either be inert, or may

have reactive capability or pozzolanic activity.

Pozzolans are materials that do not demonstrate cementing capabilities

when used alone, but in combination with other materials, such as Portland cement

or lime, will interact with these materials to form a cementitious product. The most

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important inorganic systems in use are: Portland cement, lime/fly ash, kiln dust,

Portland cementlfly ash, Portland cementilime, Portland cementhodium silicate.(’)

2.1.2 Choosing the Best S/S System for a Waste;.?/

.’\

“Aqueous wastes that are designated hazardous by EPA, especially those,.

that are liquid; are among those most commonly considered for ... treatment’’(a) by,“

stabilization/solid ification (S/S) technologies. A wide variety of both radioactive and

chemically hazardous wastes are treatable with S/S technology. These include

liquids, sludges, filter cakes, contaminated soils, and ash. S/S technologies are

often used with chemically hazardous wastes contaminated with metals and are

routinely used with low-level Radioactive wastes of all types.

The physical and chemical properties of each waste must be thoroughly

studied to determine which s/s technology is best suited for treatment of that waste.

There are no “standard” test methods for determining the most effective treatment

for a given waste. S/S treatability studies are carried out on hazardous wastes to

develop the formulation which eliminates or reduces the hazard potential. Important

properties of the waste which should be considered when choosing a s/s technology

are as follows: toxicity of the hazardous constituents, waste medium, solids content,

particle size, particle distribution and shape, and

waste constituents which may act as inhibitors (i.e.,

chemical properties, including

boric acid, some inorganic salts

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and metal compounds) and accelerators (i.e., lime, calcium chloride) to the curing

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process.(g)

Toxicity (or potential toxicity) of a waste is of

determining the s/$ process to be applied, as well as,,,p,/

primary importance in

the required regulatory

interaction and method of di&posal.’- Toxic components of the waste can’ be.. .’\

described either as leachable or non-leachable depending on the particular leaching. .

test and Ieachantbeirig applied. Though most concern has been about the

leachable toxic constituents in the waste, the non-leachable components are also

of concern as the actual leaching conditions in the environment may be different

than those tested in the laboratory.

Particle size, distribution, and shape in waste materials directly effect the

physical properties of the sofidproduced by the S/S process, as well as the handling

characteristics of the waste solution or slurry. For example, certain paper mill

wastes appear solid at only a few percent solids in water, due to the fibrous patticles

in suspension, while fly ash slurries remain pumpable at close to 50 percent solids

due to the smooth, spherical shape of the particles. Particle size, distribution,

and shape are also important from a chemical reaction standpoint, as agglomerates

of smaller waste particles or large waste particles could decrease the waste/reagent

interface, thus affecting the s/s reactions.

Since the S/S chemicals must be mixed with the waste in order to achieve

the solidified waste, the

concern. These waste

specific gravity and viscosity of the waste are of primary

properties often affect the choice of the equipment and

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I energy to use for mixing. For example, certain materials, termed dilatant, exhibit

1 increasing viscosity with increasing rate of sheer. Dilatant materials can literally turnI

solid inside a pump.

I The chemical~nature of a waste greatly effects the choice of a s/s technology.;,?/

~ There are two basic types of chemical interactions between the waste and the S/S:\

1

reagents thai affect solidification: (1) inhibition and (2)acceleration .(12) Chemical. .

inhibitors, which include boric acid, some inorganic salts and metal compounds in

I the waste, tend to slow the rate of setting effecting the hardening of the solidified

1. product. Conversely, chemical accelerators, such as lime or calcium chloride, work

+Jto speed the setting time of the solidified matrix. Controlling the effects of inhibitors

I and accelerators in s/s waste mixtures is essential in producing an environmentally

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stable treated waste. ‘ -

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2.2 Regulatory Background

The treatment and disposal of hazardous wastes are regulated primarily by

two federal laws and their amendments. The Resource Conservation and Recovery

Act (RCRA) of’1976, as amended k)ythe Hazardous and Solid Waste Amendments

(HSWA) of 1984, gives the US EPA the authority to regulate the disposal of

hazardous wastes and to set treatment standards. The second major regulation for

hazardous waste is the Comprehensive Environmental Response, Compensation

and Liability Act (C ERCLA) of 1980, as amended by the Superfund Amendments

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and Reauthorization Act (SARA) of 1986. CERCLA regulates the cleanup of spilled

materials and abandoned waste sites.

US EPA is responsible for establishing treatment standards for each type of

hazardous waste. The treatment standards are based on the Best Demonstrated;>?/

Available Technology (BDAT), rather than on risk-based or health-based\

standards. In order to”be deemed. ....

must: ., \ +% \

(1) offer the greatest reduction

the BDAT for a waste type, the technology

of toxicity, mobility, or volume of the waste;

(2) be demonstrated to work at the full-scale level, and;

(3) be commercially available.

Stabilization/solidification has been identified as the BDAT for a variety of waste

types containing both organitiand inorganic contaminants.

2.3 Basic Cement Chemistry as Applied in Solidification/Stabilization Processes

The most commonly used s/s processes utilize Portland cement, lime and/or

fly ash as the reagents. As discussed in later sections of this document, an

understanding of the interaction between the cementitious binder and the waste is

fundamental in characterizing the effectiveness of the s/s process. Thus, an

explanation of the petilnent cementitious reactions for the setthg of the SISwaste

is included herein.

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Cementitious reactions refer to the basic hydration reactions that occur when

cement clinker and water are mixed together, resulting in stiffening, hardening,

evolution of heat, and finally development of long-term strength. The hydrates

that form from the fpur principle compounds determine most of the characteristics& /J

of the hardened cement. The ptimary cement compounds include: tricalcium silikate.. :\

or alite (C$), dicalcium silicate or belite (CZS), tricalcium aluminate (CA) and

,,.tetracalcium aluminofewite (C4AIF).’ The mineral gypsum (CaSOq) is added to the

cement during the final cement grinding and functions to help slow the rate of

setting.

When cement and water are mixed together, the C$ hydrates and hardens

rapidly. This reaction is responsible for the initial set and early strength of the

material. Belite, or C2S, hydrates and hardens slowly, contributing to strength

increases beyond one week. The aluminates, C~A and CAAF, react, as shown

below to form calcium aluminate hydrates which provide some structure to the

system. The hydration of C$ liberates a large amount of heat during the first few

days of cement hydration and hardening, contributing slightly to early strength

development. Tetracalcium aluminoferrite is added to the cement clinkering

process to reduce the clinkering temperature and assist in the manufacture of

cement. C~AF hydrates quickly but contributes Iitile to the overall strength. The

basic cement hydration reactions are as follows:

*For brevity, this notation system represents calcium, silicon, aluminum, and ironoxides with C, S, A, and F, respectively. The subscripts denote the relative moleratios of each component, for example, 2CaOd5i02 is C2S.

,_ *?

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2(3CaO=SiOJ + 6H20 = 3CaO*2SiOz.3Hz0Tricalcium silicate (alite) Tobermorite get

2(2CaO”SiOz) + 4H20 = 3Ca0.2SiOz ●3HZ0Dicalcium silicate (belite) Tobermorite gel

)I 3CaO~AlzO~ + ~12HZ0 + Ca(Of-i)Z

Tricalciumaluminate Calciumj~ydroxide

4CaO*AlzO~”,FezO~ + }QH20 + 2 Ca(OH)zTetracalcium qluminofemte Calcium hydroxide

r3CaO*AlzO~ + 10HZO’ “+ CaSOd .2H20

Tricalcium alumiqate +. . .Gypsum

3Ca(OH)zCalcium hydroxide

Ca(OH)2Calcium hydroxide

3Ca0.A120~ ●Ca(OH)2 ●12HZ0Tetracalcium aluminate hydrate

6CaOOA120~ •Fe20~ ●12H20Calcium aiuminoferrite hydrate

3CaO*Al,0~ ●CaSOd ●12HZ0Calcium monosulfoaluminatehydrate

I1 Sulfate from the gypsum enters into solution and reacts with the aluminates

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coating them with calcium sulfoaluminate hydrate, or ettringite. Once the matrix has

hardened and is no longer plastic, calcium aluminate hydrate reacts with sulfate to. _

form secondary expansive ettringite crystals. As mentioned in later sections of this

document, ettringite can be detrimental to the long-term durability of a s/s waste.

C$ and C2S, which constitute approximately 75% of the weight of cement,

hydrate to form calcium hydroxide and cement gel. Hydrated cement contains

approximately 25% calcium hydroxide and 50% cement gel by weight. The cement

gel, also referred to as calcium silicate hydrate (CSH) or tobermorite gel, acts as the

principle binder and hardener in the cementiwater system.t17) CSH gel plays an

impodant role in the immobilization of metals within the s/s matrix, as discussed in

subsequent sections. The presence of calcium hydroxide in the mixture results in

“1 the high pH of the system, which is an important aspect of

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cement-based Sk

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2.4 Mechanisms of Stabilization

Stabilization of hazardous materials within a matrix serves to minimize

leaching by isolating the waste from the environment, especially groundwater,~,?./

thereby disallowing migration of waste constituents. Stabilization may be,. ‘x

accomplished by physically isolating the waste from the environment, reducing its,.

volubility, and/or deceasing. its surface area. Several chemical and physical

mechanisms effect the degree to which hazardous constituents are immobilized

within a s/s waste. Extensive laboratory investigations have been published which

examine the mechanisms of metal immobilization in cementitious systems. The

basic immobilization mechanisms are discussed in the following sections. It should

be noted, however, that the following sections highlight only the simple

mechanisms, and that numerous studies, cited later in this document, confirm that

stabilization of metallic species is achieved by a combination of the simple

mechanisms. A description of each of the following mechanisms is presented in

the following sections: encapsulation, isomorphic substitution, precipitation, redox

potential, and chemisorption.

2.4.1 Encapsulation

Encapsulation is one of the most commonly used methods of containment.

As the name implies, encapsulation refers to the isolation of waste from the

.

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environment by a very low permeability matrix which surrounds the waste.!

Microencapsulation refers to the trapping of individual microscopic particles, suchI

as metal ions in a cement gel or silicate gel matrix. Entrapment of larger

aggregates of waste material in the matrix is referred to as macroencapsulation.$?. /

The term “microencapsulation” refers to the process of trapping hazardous.. .-\

waste constituents within the pore spaces of a solidified matrix. In this process,. .

individual particles or agglomerates retain their identities but are entrapped by an

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I impervious material. With the passage of time, the stabilized materials may

degrade into smaller particles and, as a result of microencapsulation, most of the.

hazardous constituents will remain entrapped in the matrix. However, as1.-’.

I encapsulation is a physical process, the rates of contaminant release from the

stabilized mass may increase as the particle size decreases and more surface area

is exposed.

I The term “macroencapsulation” refers to the coating of hazardous waste

constituents with an impermeable layer. The hazardous waste constituents are held

!in discontinuous pores within the stabilized matrix. The success of

I macroencapsulation in isolating hazardous constituents from the environment is

highly dependent on both effective coating reactions and thorough mixing.

IPhysical degradation of the stabilized material, even to relatively large particle sizes,

can result in the entrapped materials migration. Thus, hazardous contaminants

which have been stabilized by macroencapsulation alone may find their way into the

environment if the integrity of the matrix is not maintained. Environmental stresses

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1 such as repeated cycles of wetting and drying, or freezing and thawing, introduction

of percolating fluids, and physical loading stresses may cause the stabilized mass

to break down over time.f20)

These two stabilization mechanisms demonstrate how a hazardous waste@/

constituent can be -,physically isolated from the environment. However, if~.

encapsulation is the only operative stabilization mechanism, the isolation of. .

hazardous m“a?erkdsfrom the-environment is dependent upon the integrity of the)

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matrix. Isolation, in turn, depends primarily on the permeability of the matrix.

S/S wastes which have been stabilized through macroencapsulation

more prone to aging, than those which have been microencapsulated. As

stabilized material degrades over time, the macroencapsulated waste particles will

be exposed to water which permeates the SIS matrix, and thus susceptible to

leaching. The microencapsulated waste pafiicles will remain physically entrapped

in the microscopic pores of the waste material until further degradation of the waste

material occurs.

are

the

2.4.2 Isomorphic Substitution

The isomorphic substitution mechanism refers to the substitution of metallic

ions for calcium in the structure of CSH gel. The following general reaction

describes this mechanism:

CSH+M* MCSH + ca2+

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where CSH denotes CSH gel, M denotes the metallic ion, MCSI-I denotes the

metallic CSH gel, and Ca2+denotes the calcium ions which have been replaced by

the other metallic ions.

Bhatty ’22)asserts that replacement of the calcium ion from the structure of;.?,.1

the CSH gel was generally found to occur in those CS1-tgels having a high calcium-,. .-Y

silica mole ;atio (i.e. more calcium ions compared to fewer silica ions in the CSH

gel). In addi&m. the author states that the immobilization of metallic ions by this

mechanism is expected to be limited because of the limited number of calcium ions

that can be replaced from the structure of CSH gel, while allowing it to retain its

properties.

.—2.4.3 Precipitation

The chemistry of inorganic waste constituents in s/s systems is dominated

by hydrolysis. Metallic species can, through chemical reaction, be precipitated as

Iow-volubility hydroxides, sulfides, silicates, carbonates, and other simple or

complex species. Chemical precipitation of metal species serves to reduce

volubility and leachability. Precipitates can then be contained within the stabilized

mass as part of the material structure.

Metal hydroxide precipitation occurs as a result of pH control. Most heavy

metals are relatively soluble in acidic solutions. In the simplest of systems, as alkali

is added to neutralize the acid and the pH is raised, heavy metal ions precipitate out

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of solution in their hydroxide forms. Numerous studies, as described in subsequent

sections have identified the complex metal species present in s/s wastes. However,

an examination of metal hydroxide solubilities in simple aqueous alkaline systems

is useful in understanding the amphoteric nature of the metal hydroxides commonly;;~,/

precipitated in s/s sys~ems. In general, high pH is desirable since metal hydroxides

have minim’um volubility in the range of pH 7.5-11. Volubility curves for various

metal hydroxides ‘inwater are given in Figure 1, below!23)

100

10

1.0

0.1

0.01

O.boi

0.0001

PH

Figure 1 Solubilities of Metal Hydroxides as a Function of pH

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According to Figure 1, metal hydroxide species reach minimum volubility at

different pH values. The figure shows that while the optimum pH for minimum

cadmium hydroxide volubility is approximately 11.2, the optimum pH for minimum

zinc hydroxide solu~ility is approximately 9.2. For this reason, the optimum pH of:?/

a waste mixture containing different metallic species must be a compromise.’ In-Y

addition, cedain metal hydroxides, such as lead hydroxide, exhibit solubilities above,.

the current T&P. limit even atoptimum PH.

Sulfide precipitation of heavy metals occurs when sulfides are present in the

treated waste mixture. Metal sulfides generally have solubilities several orders of

magnitude lower than metal hydroxides and are not as sensitive to changes in

PH.(Z4J

Metals can also be precipitated as metallic carbonates. For example, lead

can be precipitated using alkaline lime and dolomite [CaMg(CO~)2] to yield lead

carbonate. Metal carbonates are typically less soluble than metal hydroxides and,

at high pH, metal carbonates can be formed from metal hydroxides.(25) The stability

of metal carbonate species is highly dependent upon pH. Although metallic

carbonates are quite stable at high pH, under strongly acidic conditions the metal

may be redissolved and become free to migrate as a solute into the environment.

The formation of heavy metal silicates can further reduce the solubiiity of

metals in waste treatment. Heavy metal silicates do not actually exist in solution as

specific compounds as do hydroxides and sulfides, but rather exist as metals in

combination with a variety of polymeric silicate species. These polymeric species

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form silica gel when silicate is exposed to divalent metal compounds. The volubility

of heavy metal silicate species can be approximated by the volubility of the silica

geLt2sJ Metal oxide-silicates formed in the gel are less soluble over low pH ranges

than heavy metal hydroxides, and have the added benefit of being held within a:?/

polymeric structure that is resistant to acid attack.-\

2.4.4Redox l?otential~

Reduction and oxidation techniques are important in s/s treatment for

consenting metals to a more desirable valence state for precipitation. The redox

potential, Eh, is the oxidation-reduction potential referred to the hydrogen scale,

expressed in millivolts. O-xidationis defined as a reaction that results in the loss

of electrons by a chemical species, whereby the species donating the electron is

oxidized. The converse, gaining an electron, is referred to as reduction. The

presence of strong oxidants and reductants in the waste matrix can change the

valence state of a number of metals, thus affecting their chemical speciation and

resulting solubilities by orders of magnitude. Redox potential control is most

applicable to the stabilization of arsenic, chromium, iron, mercury, manganese,

nickel, and selenium as these seven metals are commonly found to have more than

one valence state in stabilization systems.

The use of Eh - pH diagralms in soil and geochemistry is widespread because

of the important influence of both variables on the stabilities of minerals in nature.

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Eh - pH diagrams can also be useful in the analysis of complex Sk waste systems,

though the diagrams are designed to represent chemically simple systems. As

chromium is among the metals examined in this study, the effects of redox potential

on chromium stabiijzation in sk systems will be discussed. In Klich’s study(30),Eh;;?/

-pH data were considered as one indicator in determining the speciatioh of‘x

chromium in the sk wastes. In that study, mean Eh values ranged from -0.06 to 0.2. .

volts, and mean pi-l values ranged from 10.1 to 12.2. Figure 2, below, presents the

Eh-pH diagram for part of the Cr-O-H system.

1.2

1.0

0.8

0.6

0.4

s-0.25

0.0

-0.2

-0.4

-0.6

-0.8

\

SYSTEM Cr-o-li25%, 1 bar J

1I1

(Cr(OH)J

t I t 1 1 I

2 4 6 8 10 12 14PH

Figure 2 Eh-pH Diagram for Part of the Cr-O-H System

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Based on the Eh and pH values above, it is noted that the chromium phase Cr20~

is the stable phase in the range for the s/s wastes. Further discussion as to the

immobilization mechanisms of chromium is presented in subsequent sections.

Some metals, such as cadmium and zinc, do not exhibit multiple valuence>./

states in aqueous systems, but “aresensitive to changes in the redox potential of the.-\

system. Figure 3, below shows an Eh-pH diagram for cadmium developed by

i Dragon.

Ichanges in

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According to the diagram, the speciation of cadmium changes as

the redox potential of the system occur.

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1 .35791iI)H /

Figure 3 Eh-pH diagram for Cadmium

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2.4.5Chemisorption

Chemical adsorption, or chemisorption, refers to the mechanism by which

metallic ions are taken up in the structure of mineral species. Bhatty ’33)suggested;<?/

that metals could be adsorbed by tobermorite gel, according to the follotving:\

reaction: ‘ . .

where CSH denotes tobermorite gel, M denotes the metallic ion, and MCSH

denotes the metallic tobermorite gel. The author asserts that the amount of metal

retained depends on the type of tobermorite gel formed during hydration, where

tobermorite gels with a low calcium-silica mole ratio (i.e., fewer calcium ions

compared to more silica ~ions in the CSH gel) appear more likely to favor

immobilization of metal ions by this mechanism. In addition, as described in

subsequent sections, recent studies have acknowledged that this is the probable

mechanism by which cadmium, chromium, and lead are retained within the

cementitious matrix.

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2.5 Immobilization of Metals in Stabilized/Solidified Wastes

The ability of s/s reagents to immobilize heavy metals in wastes has been

studied a great deaj in recent years. The metals of concern for this study include~?/

cadmium, chromium, lead, and zinc, and the subsequent discussion will focus on.,. -\

the immobiltiation of these metals in s/s systems. Klich ‘~) has provided a current. .

and thorough’’’summary of the literature regarding the immobilization of these and

other metals in her dissertation.

Recent studies by Cocke and Mollah ’35)have provided insight into the

chemical binding and interactions between hazardous metal substances and

Portland cement. Specifically, priority metal pollutants such as, zinc, lead,

cadmium, chromium, merctiry~ alndbarium, were studied to determine the models

for the interaction of each metal with the cement matrix. Figure 4, below is a

pictoral summary of their findings. As shown, cadmium, zinc and lead form mixed

hydroxides and adsorb to the surface at alkaline pH. Mercury is present as a

surface particulate, HgO, while barium is present as the sulfate and carbonate.

Chromium was found to incorporate into the calcium silicate hydrate (CSH) matrix

in some fashion, which was unknown at the time of the atiicle’s publication.

Leaching tests showed that the zinc on the outer sutiace is effectively removed

during acid attack.

23

Surface Particles

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Precipit nt~>

cd\iCoCdCOH). ‘

.; ;;;;;,C~Zn2(OH)6 -2H20~~~\

,\\\\\\\\\\\,..,,,..,,,.,,,,... .. .. .. . .. .. . . .. . .. .. .. .. Hgo..................,,,.,,,,,,\.\...\\\\\.,...>.,...,,. BaS~

BaCC$::::..,... . ... . .\.. \.. ..::\

;:

—CrL.I\ Incorporation

)..........\\\\.,.,\..,..\..:::....::::.....\\\.\.,,....,,....\,.\..,,...,,.,,......\\\\.\..,,..

:;:ss

Am...\\.......\\.\..\.....\......................~~............................................Surface

.. .... . ...---=5?- Cement Clinker

ParticleZone

C-S-H. _

Figure 4 A Summary of Models for the Interaction ofPriority Metal Pollutants with Cement

In addition to this study, research

present study is presented below.

2.5.1 Cadmium

specific to the four metals examined in the

Studies of cadmium uptake in cementitious systems indicate that cadmium

is tightly bound within the solidified matrix. Peon and Perry ’36)examined cadmium

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I 24

I1 stabilization in ordinary Portland cement/pulverized fuel ash (OPC/PFC) mixtures.

1 The authors reported that cadmium induced only moderate changes

)microstructure of the solidified matrix, and that x-ray diffractometry

in the

(XRD)

I examination confirmed the presence of the calcium hydroxide phase. Compressive~~,/

!strength testing revealed that the addition of Cd greatly reduced the strength of the

,. :\

1solidified p~oducts, however, leaching tests indicated that Cd was well retained by,.

the OPC/PFAI m@rix.(~7) .

I Cartiedge, et al.(38)examined the s/s of cadmium salts using Portland cement

1fixing agents. The study used TCLP leaching tests, conduction calorimetry, and

.’:1solid-state NMR as a function of time to investigate the behavior of cadmium salts

Iin cement-based solidification. According to the report, both cadmium hydroxide

I

(Cd(OH)2) and cadmium nitrate (Cd(N03),) caused a slight acceleration of cement

hydration. As cadmium nitrate was added to the mixture, cadmium hydroxide began

I to precipitate out of

Iprecipitation of calcium

solution as a solid,

hydroxide (Ca(OH)2).

providing nucleation sites for the

However, the study noted that other

J

than the “minor acceleration of silicate hydration, the Cd salts have little effect on

I the cement matrix.” Citing that cadmium and calcium ions have the same charge,

1

and nearly the same ionic radius, Cartledge, et al. suggest that the substitution of

cadmium for calcium in crystal lattices maybe a method of cadmium immobilization.

j In their study, however, the authors suggest that the mechanism for cadmium

Istabilization was microencapsulation of solid Cd(OH)2 within CSH gel and/or calcium

hydroxide, due to the presence of only small amounts of free Cd’+ in solution. The>

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authors assert that cadmium leaching is minimal because

accessible to water nor in a very soluble chemical form.”(39)

2.5.2 Chromium ~;,~,/

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it is “neither very

In aqueous systems, chromium is found in two valence states, Cr(Vl) and

Cr(lll). In a sfudyby Cocke and Mollah ‘40),the authors suggest that the aqueous

chemistry of Cr(lll) ions greatly influences the fixation of chromium. At higher pH

(above 8), as in the case of s/s systems, the Cr(OH)- ion may exist in appreciable

amounts. It was noted that these ions were not likely to be absorbed by the

negative silicate surfaces; and, like cadmium, the chromate ion may serve as a

nucleation site for the precipitation of hydrates, becoming dispersed in the bulk of

the solidified matrix.

A study by Kindness, et al. ’42)demonstrated that the mechanism of

chromium stabilization in blast furnace slag/cement (BFS/OPC) blends was through

reduction of Cr(Vl) to Cr(lll) by S2- (a constituent of slags), and subsequent

incorporation into the cement hydrates. Macias ’43)asserts that slags continue to

release S2- ions because of their slow hydration, thus inhibiting the chromium from

oxidizing back to the C~ speciation. In their article, Bonen and Sarkar ‘a) state

that the excellent retention of Cp+ is related to the formation of insoluble Cr(OH)~.

nHzO.

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2.5.3Lead

An early study by Thomas, et al. ’45)demonstrated that lead forms mixed

solids during cemen~ hydration, as supported by the authors’ titrations of lead nitrate;.,~,

against calcium hydroxide and calcium’sulfate. During the titrations, the pH end‘\

point fluctuated between 8.5 and 10, which Thomas explained in terms of

dissolution of “’the.first-formed solids and reprecipitation. Using NMR, Cartledge et

al. ’46)confirmed

reactions caused

the extreme retardation of the aluminate and silicate hydration

by lead salts in cementitious systems. The authors point out that

previous studies proposed that the retardation effect of lead salts is caused by the

rapid formation of a gelatinous coating of lead salts around the cement clinker

grains, thus preventing contacfbetween the grains and water. The study concluded

that as the pH of the cement system fluctuates during the hydration process, lead

salts undergo solubilization and reprecipitation, resulting in the presence of lead

salts on the surfaces of cement minerals. The authors assert that the Pb salts are

therefore readily accessible to leaching fluid.

These results were suppoited by the studies conducted by Cocke and Moilah

’47)which confirmed, using microscopic analyses, that lead compounds were

located on the outer surfaces of cement particles. The study also demonstrated

that lead was present in the less soluble silicate, carbonate, and hydroxide forms,

and not the more soluble oxide form.

27

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2.5.4 Zinc

Though zinc is not listed as a RCRA metal, it can be found at significant

concentrations in fiazardous waste streams. Cocke et al. ’48)have proposed that;,?/

zinc retards the hydration and setting of cement by precipitating an amorphous layer.-Y

of zinc hydroxide onto the surface of the cement clinker grains. The surface. .

compound wbs identified as CaZn2(OH)G Q 2H20, resulting from calcium aided

adsorption of the normally anionic zinc species at high pH. The study by Peon and

Perry ’49)confirms the notion that Zn greatly retards the hydration of cement. The

authors also state that the presence of zinc produces a significant change in the

pore structure through enhanced ettringite and monosulfate formation. It was also

noted that zinc caused substantial lowering of the pH of the system, and that the pH

of the system was not high enough to resolubilize the amphoteric Zn.

2.6 Metals Leachability as a Function of pH

The success of s/s treatment is expected to depend on the pH of the material

for metals that are immobilized as hydroxide, carbonate, sulfide, silicate, and

phosphate precipitates. However, none of the common leaching tests require pH

measurement and data to correlate pH to metal mobility are sparse. Recent studies

have attempted to correlate the final pH of the Ieachate with the mobility of metals

from s/s wastes.

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28

! In 1992, Jones, et al. ’51)performed a study in which the effects of waste

constituents on s/s waste leachability were evaluated. The authors plotted metal

concentration versus final Ieachate pH for s/s wastes that had been subjected to the1“1 EP leaching test {EPA Method 131 OA, SW 846). The authors noted that the

;.>9/amphoteric nature of cadmiuml volubility was evident since Cd concentrations~ .. ‘\

tincreased as the pH rose above 10.5. In addition, nickel concentrations in the. .

j:,,

Ieachate showed a ‘similar pH dependency, though less pronounced. Ni

I concentration increased approximately 2 orders of magnitude below pH 7.5.

-1 “Chromium concentrations decreased slightly with increasing Ieachate pH.

-1.,.>Trussel and Batchelor ’52)noted a correlation between pi-l and the leaching

I of metals from the s/s material in their 1996 article. The authors noted that the

Ilower the pH, the greater the-metal leaching. However, the degree to which this

correlation was observed varied for different metals. Cadmium and mercury were

1 shown to be highly leachable at acidic pH, whereas moderate mobilization was

/

noted for lead and chromium. In 1996, Erickson and Barth ’53)examined the

relationship between the degree of lead immobilization and Ieachate pH. The

I authors note the high volubility of lead at acidic and near neutral pH values. In

11I

addition, the authors suggest a pH range of minimum volubility for lead at pH 10.5-

12, and noted the amphoteric behavior of Pb in s/s materials.

29

2.7 Long-Term Performance of Stabilized/Solidified Wastes

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2.7.1 Methods for the Analysis of Long-Term Performance of Stabilized/SolidifiedWastes

.;:?/

In recent ye~{s, several studies have shown the failure of leaching tests

alone to p~ovide information on the durability of metals in stabilized/solidified

wastes. Wh~@ tiie TCLP has value for comparative and regulatory purposes, it

gives no information about the chemical interactions between the waste and the

binder. As well, numerous studies have verified that the TCLP does not accurately

simulate long-term leaching under varying environmental conditions. The

TCLP was designed to simulate the conditions that a waste would be exposed to

if placed in a sanitary land~ll. ‘The procedure assumes that acetic acid, produced

by microorganisms in the landfill, and leaching at about pH 5 would be the expected

conditions. However, many sh wastes are disposed of on-site, and thus are

exposed to site-specific conditions. The contents of this section should help to

elucidate the analytical methods, besides leaching tests, which can be employed

to describe and possibly predict the permanence of metals in stabilized/solidified

wastes.

Klich ’56)asserts that the need to incorporate the use of microscopy at ail

levels of resolution into the long-term durability studies of s/s wastes is fundamental

in gaining an understanding of the degradation mechanisms which effect leaching

of hazardous constituents. The methods of powder x-ray diffraction (XRD) analysis,

30

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optical petrography, scanning electron microscopy (SEM) combined with energy

dispersive spectroscopy (EDS), transmission electron microscopy (TEM), electron

probe microanalysis (EPMA), Fourier transform infrared spectroscopy (FTIR), and

x-ray photoelectron spectroscopy (XPS) are among the analytical tools used by

Klich and other researchers to

with the aging of s/s wastes.

>?/“

investigate the microstructural changes associated

Powder XRD aids in the identification of the dominant crystalline mineral

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constituents using their characteristic sets of diffraction spectra. XRD can be used

to confirm the presence or absence of specific mineral phases in the cementitious

material. Optical petrography allows the user to characterize the effects of

weathering in aged s/s wastes contaminated with metals. Petrographic microscope

techniques can be used to ‘evaluate geologic and soil materials. SEM is a

frequently used microscopic method because of its high spatial resolution, and

when combined with EDS, allows easy recognition and identification of metal

contaminants within the cement matrix. TEM is capable of even greater spatial

resolution, and selected area diffraction patterns are helpful in determining the

structure of crystals and the orientation of the crystal phases within the material.

EPMA is a non-destructive technique for chemically analyzing small areas of solid

samples, and is therefore useful in studying the containment of metals in cements.

FTIR is useful for molecular characterization, providing insight into the molecular

structure. FTIR has been used to investigate the hydration of cement, by monitoring

the changes in the vibrational spectra with time. XPS can provide qualitative and

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semi-quantitative information on the chemical state of elements using binding

energies of those elements. FTIR and XPS have been used recently to study the

effect of carbonization on s/s wastes.

.;,?./

2.7.2 Simulated Long-Term Performance Study Results

Sequentiator multiple extraction procedures have been employed to study

the long-term leaching characteristics of s/s wastes. US EPA developed the

Multiple Extraction Procedure (MEP, SW 846 Method 1320) to simulate the leaching

that a waste undergoes from repetitive extractions. This procedure serves to reveal

the highest concentration of each constituent that is likely to leach in a natural

environment. Based on this–type of assumption, other researchers have used

multiple or sequential leaching procedures, as described below, to evaluate long-

term leaching of metals from s/s wastes over a relatively short term.

In 1994, Lee, et al. ‘6*)presented a method for studying long-term metals

leachability in solidified wastes called the multiple toxicity characteristic leaching

procedure (MTCLP). In this procedure, the first extraction sequence uses the

TCLP, while the following 8 extraction sequences follow the TCLP, except that a

synthetic acid rain extraction fluid (sulfuric acid/nitric acid - 60/40 by weight, pH =

3.0) is used. The authors assert that the MTCLP can be used to simulate the

leaching of a waste subjected to repetitive precipitation of acid rain on a sanitary

landfill.

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Andres, et al. ’61)studied the long-term behavior of steel foundry wastes

stabilized with cement materials using a dynamic leaching test (DLT). The DLT was

adapted from the American Society Test ANS 16.1. A monolithic cylindrical sample

was immersed in djstilled water at a specified ratio of Ieachate volume to sample;:?,/

surface area. The Ieachant was renewed at frequent intewals and “the.. -\

concentration of metals was determined. The authors concluded that lead has

greater mobility than zinc, and that the mobility of zinc changed with differing s/s

matrices.

Webster and Loehr ’62)performed a study in which the long-term leaching of

metals from concrete products was analyzed using a sequential extraction

procedure employing both acidic extraction fluid and seawater. The authors

concluded that pH alone could not fully explain the leaching behavior of metals in

the concrete products. In addition, the authors noted that the severe environment

created during the acidic sequential extractions resulted in the leaching of

substantial amounts of alkalinity from the concrete, allowing the Ieachate pH to drop

below 4, where metals are highly soluble.

2.7.3 Long-Term Performance Study Results

A significant unresolved issue of stabilizatiordsolidification is how well the s/s

treated waste maintains its immobilization characteristics over time. The question

is not whether s/s wastes will eventually release their contaminants into the

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I environment, but whether this release is environmentally acceptable. Since s/s

technologies for waste treatment have only been in use for a few decades, the

number and duration of research studies of particular s/s products must be based1

on the available sfioder-term field data, laboratory tests, and models of leachingf,?/

behavior... “\

Per~ et al.(ti) used the TCLP to study the long-term leaching behavior of four

Ii types of wast&s @ntaminated with metals or inorganic. The study showed that the

I effect of time on TCLP results was highly waste-dependent. For some of the

wastes, Ieachate concentrations remained stable with time, while in other wastes,

Jthe concentration of metals in the Ieachate increased. Similar results were obtained

by Akhter and Cartledge(65) and Cartledge(66), except that both increases and

decreases in metals Ieachabfity, as measured by the TCLP, were observed with

aging. In some cases, spectroscopic analysis was used to link these changes with

I changes in the chemical structure of the stabilized waste.

Badamchian, et al. ‘Gnperformed chemical and physical analyses to evaluate

the long-term effectiveness of the s/s of several wastes stabilized during US EPAs

Superfund Innovative Technology Evaluation (SITE) program. The TCLP results

‘1

from the study demonstrated that metals remained immobilized over the six-yearIperiod, for two of the SITE s/s technologies, and that the concentrations of TCLP-

Ieachable metals in all of the aged samples were below the RCRA threshold limits...1

I The second portion of this study, which was initiated to examine the mineralogical

changes in the wastes afler six years, was presented in Klich’s dissertation.@) The

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results of that portion of the study identified chemical weathering features and

mineralogical changes that were promoted by pervasive cracking at the macro-,

micro-, and submicroscopic scales. The cracking observed within the cement matrix

and within the wask aggregates allowed moisture, air, and groundwater to interact:?/’

with the treated waste constituents. The study confirmed that metals migrate from... ‘<

waste aggregates into the porous cement micromass overtime, and as discussed. .

previously, tfie manner in which the metal is immobilized within the cement

micromass is different for each metal. The author also asserts that the same

environmental issues that affect the durability of concrete must be considered when

evaluating the durability and performance of s/s wastes.

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3.0 PRfOR RESEARCH AT THE UNIVERSITY OF PllTSBURGHAND ORIGINAL SAMPLE PREPARATION

3.1 Prior Research at the University of Pittsburgh

In 1994, res~archers at the University of Pittsburgh’s Department of\

Chemical and Petroleum Engineering and Department of Civil and Environmental: +. ,,

Engineering began wo~kon the project titled, “Treatment of Metal-Laden Hazardous

Wastes with Advanced Clean-Coal Technology By-Products,” funded by the United

States Department of Energy. “Thegoals of the project, to be completed in two

phases, were to (1) perform stabilization/solidification treatability studies to

determine if Clean-Coal Technology (CCT) by-products were effective in.—

immobilizing the metals present in the various wastes according to the TCLP

(Phase 1 work), and (2) demonstrate the full-scale effectiveness of s/s of metal-

Iaden wastes using CCT by-products (Phase 2 work). To date, the Phase 1 studies

have been completed, confirming the effective stabilization/solidification of metals

in various hazardous waste streams using CCT by-products,

As previously mentioned, the s/s waste samples examined for the purposes

of this document were gathered from the original samples prepared during Phase

1 of the research project described above. The following sections briefly describe

the characteristics of the s/s reagents and the wastes used in the original study, and

the preparation of the resulting treated waste samples.

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3.2 Original Sample Preparation

Stabilization/Solidification Agents

;??/

The Clean Coal Technology (CCT) program refers to a Federally furided.-\

cooperative effort with selected electric utilities and others to demonstrate a new. .

generation of! innovative coal processes which are environmentally cleaner and

more efficient than conventional coal-burning processes (US DOE, 1991 ). The

resulting waste stream from the CCT processes is fly ash rich in lime. The

pozzoianic properties of the fly ash, coupled with the higher than normal lime

content make the CCT by-products attractive as s/s reagents. A brief description

of each of the CCT by-producls used in the original study, as well as the respective

CCT process, is included in Appendix A. In addition, further information on the CCT

by-products, as well as the results and conclusions of the Phase 1 study are

documented in the theses by Clifford and Prints.

The three CCT by-products used in the original study each originate from

slightly different CCT processes. Prior to the s/s activities, each of the CCT by-

products was characterized to determine its geochemical and reactive propetiies.

In addition, a comprehensive metals analysis of each of three CCT by-products was

performed prior to the start of the original project. The metals analyzed include the

eight RCRA metals (As, Ba, Cd, Cr, Pb, Iig, Se and Ag) and seven other metals

(Sb, Be, Cu, Ni, Tl, V and Zn) which may be regulated in the future. A total

37

I constituent analysis was performed to see which of these metals were present in

I each by-product and in what concentration. As well, a TCLP metals analysis wasI

)completed to determine the actual leachable metals concentrations in each of the

I CCT by-products. The results of this very thorough metals analysis demonstrated

! ;;>~,/

) that the CCT by-products were’ nc}tcharacteristically toxic in their own right, and”thatI .. -\

they would not contribute to the leachable metals concentrations in the subsequent.

\ treated

1

waste~mixtures.

3.2.2 Hazardous Waste Materials

The hazardous wastes chosen for the original study included three

contaminated soils. Metals””analysisof each of the wastes demonstrated that each

contained significant amounts of leachable lead, and was therefore characteristically

hazardous as defined by the US EPA. The “Munitions Soil”waste is a contaminated

soil from a former military munitions depot, where lead-containing munitions were

stored on site. The “Industrial Soil”waste is a contaminated soil from an industrial

site. The waste is a mixture of contaminated soil and debris from plant operations

in the area. The “Wastewater Treatment Plant (WWTP) Soil” is tainted soil from a

former hospital wastewater treatment plant, which used lead piping in the sewage’

distribution system.

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3.2.3 Treated Waste Mixtures

One of the goals of the Phase I work was to perform a treatability study using

different combinatio~s of CCT by-products with hazardous wastes. In so doing, the~~/

wastes were combined with the CCT by-products in the following ratios, 10YO,30Y0,.. .-\

50?40 (where 10% denotes a combination of 1 part CCT by-product with 9 parts,. .

waste) in an effort to determine which by-product dosage was most effective in.’

immobilizing the metals present in the waste. The number of CCT by-prod uctiwaste

combinations examined during the treatability study was extensive, however, only

a select number of the original treated waste samples were available for this long-

term study. The treated waste samples which were used in this study include:

Munitions Soil with 10O?40CFBC Residue, Munitions Soil with 50% PFBC Residue,

Munitions Soil with 50% Spray Dryer Residue, WWTP Soil with 50% PFBC

Residue, WWTP Soil with 50% CFBC Residue, and Industrial Soil with 50V0 PFBC

Residue.

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4.0 EXPERIMENTAL METHODS

4.1 Leaching Tests

<;/<,

4.1.1 Toxicity Characteristic Leaching P~ocedure (TCLP):\

\,.

The TGLl?*\is designed to evaluate the leaching of metals, volatile and

semivolatile organic compounds, and pesticides from wastes that are categorized

under RCRA as characteristically toxic and can be used on other waste types. In

the TCLP, the particle size of the waste is reduced (if waste particles are unable to

pass through a 9.5-mm standard sieve) and the solid phase is extracted with an

amount of extraction fluid equal to 20 times the weight of the solid phase. The

extraction fluid used is a function of the alkalinity of the solid phase of the waste.

Following extraction, the liquid extract is separated from the solid phase by filtration

through a 0.6 to 0.8-mm glass fiber filter. The filtered sample is then known as the

“TCLP extract” and is ready for chemical analysis.

The TCLP test has been most commonly used by the US EPA and state

agencies to evaluate the leaching potential of stabilized wastes.

TCLP is the test required by RCRA implementing regulations

toxicity.

In addition, the

for determining

40

4.1.2Shake Extraction Test

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The Shake Extraction Test (ASTM D3987-85 “Standard Test Method for

Shake Extraction of Solid Waste with Water) is a leaching test in which distilled~f/

deionized water is used as the extraction fluid. As in the TCLP, the solid waste is.. ‘Y

first ground’to reduce the particle size of the solid sample to approximately 9.5 mm.. .

The crushed’’’solid is then extracted with an amount of extraction fluid equal to 20

times weight of the solid phase. The solid waste is then extracted using a rotary

agitator to mix the solid with the extraction fluid for 18 hours. The Ieachate is then

filtered prior to analysis for inorganic constituents. The shake extraction test is

designed to provide a rapid means of obtaining an aqueous extract.

., _

4.2 Analytical Procedures and Techniques

4.2.1 Sample Grinding/Preparation

According to the TCLP and the shake extraction test, solidified samples must

be ground to achieve a particle size less than 9.5 mm prior to extraction. In order

to accomplish the particle size reduction required by the leaching tests, the s/s

cylinders were first crushed with a hammer into smaller pieces. The smaller pieces

of the sample were then easily ground using the Thornas Wiley Model 4 grinder,

available in the Department of Civil and Environmental Engineering. Ground

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samples were then ready for extraction according to the TCLP and the shake

extraction test.

4.2.2 Digestion Procedure;,,>,/

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The ~oal of the digestion of aqueous extracts is to chemically reduce the

complexed Species in the Ieachate to simpler and more readily analyzable

compounds. The extracts of both the TCLP and the shake extraction tests were

prepared for metals analysis using a digestion procedure (EPA SW-846 Method

301 OA:Acid Digestion of Aqueous Samples and Extracts for Total Metals Analysis

by FLAA or ICP Spectroscopy). The procedure stipulates that concentrated nitric

acid be added to a portion of the extract. The mixture is gently heated and reduced.

The volume is then recovered with the addition of distilled deionized water. The

resulting digested sample is then ready for analysis by atomic absorption

spectroscopy (AAS),

4.2.3 Flame Atomic Absorption (FLAA) Spectroscopy

Flame Atomic Absorption Spectroscopy analysis was completed using the

Perkin-Elmer 1100B Atomic Absorption Spectrophotometer in the Department of

42

Civil and Environmental Engineering. Directions for the setup and calibration of the

machine as well as for sample analysis are provided in the document, “Using the

Perkin-Elmer1100B AA Spectrophotometer,” which is attached as Appendix C.(72)

.

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4.3 Quality Assurance/Quality Control (QA/QC) Methods “?\

In orderto ensure the comparability of the analytical data collected during the

present study with the analytical data from the prior study, the same analytical tools,

techniques, and procedures were used. The techniques for QA/QC applied during

the present study were those described in the document, “Quality Assurance Project

Plan for Treatment of Metal-Laden Hazardous Wastes with Advanced Clean-Coal

Technology By-Products,” ((2A Project Plan) prepared by J. T. Cobb, Jr., Ph.D. in

September 1994. The QA Project Plan was developed for use during the prior

study, and was applied during the present project. The QA Project Plan describes

objectives for measurement data, sampling, calibration, and analytical procedures,

and methods for data reporting. The QA Project Plan is attached as Appendix D.

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5.1 Leaching Test Results

43

5.0 RESULTS AND DISCUSSION

.~?,/

Two different leaching tests were used to characterize the mobility of metals-\

in the s/s wastes for this study. Both the TCLP and the shake extraction test were

used so that data frornthis study could be compared to that of the prior study at the

University of Pittsburgh. However, a comparison of the leaching data from the two

extraction tests also provides interesting insight into the mobility of metals from

within the s/s wastes. Of the 15 metals examined during the prior research study,

cadmium, chromium, lead and zinc were designated as metals of concern and were

thus further examined in the present study.

5.1.1 Cadmium

The analysis of cadmium leaching from the s/s wastes subjected to the TCLP

indicates that cadmium remains immobilized in the s/s matrix after two years. This

result is in direct agreement with those published by Peon and Perry, and by

Cartledge, et al. discussed in the previous sections. Cadmium concentrations in the

TCLP Ieachate from day 1 through year 2 remain two orders of magnitude below the

BDAT standard of 1.0 mg/L for each of the s/s wastes examined in this study. The

results are tabulated in Table B“l of Appendix B.

44

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The shake extraction test uses DI water as the extraction fluid and is

therefore much less harsh as compared to the acidic TCLP leaching fluid. As

expected, the concentrations of cadmium measured in the respective shake

extraction test Ieachates were less than in the TCLP Ieachates. Cadmium;.?./

concentrations in the shake extraction test Ieachate were below the detection limits“.

in each of the s/s wastes examined in this study.. .

5.1.2Chromium

Chromium mobility was also evaluated as part of this study. The

concentration of chromium in the TCLP Ieachates measured 1 day after stabilization

indicated chromium levels bebw the detection limit. The concentrations measured

in the TCLP Ieachate as part of this study after two years indicated chromium levels

one to two orders of magnitude below the BDAT standard of 5.0 mg/L for chromium.

The results are tabulated in Table B2 of Appendix B. This result is in agreement

with studies discussed previously, notably that of Bonen and Sarkar (73) who

reported excellent retention of C~ related to the formation of Cr(OH)~ c nH20.

The results of the shake extraction test Ieachate analysis for chromium were

similar to those for cadmium. Chromium concentrations in the shake extraction test

Ieachate were below the detection limits for each of the s/s wastes analyzed in this

study.

—

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45

5.1.3 Lead

The results of lead leaching from the s/s wastes subjected to the TCLP

varied for each of the s/s wastes examined. Figure 5 presents the lead;,?.,/

concentration in the TCLP Ieachates with respect to time. In four of the’ six:\

samples, thd concentration of lead increased through the 90 day or 1 year analysis,. .

but decreased in the year two analysis. In one of the samples, the lead

concentration increased from day one to year two, however, it should be noted that

the year two concentration was below the BDAT standard of 5.0 mg/L for lead. The

sixth sample, not previously mentioned, exhibited slight fluctuations in the lead

concentration in the TCLP leachate.

These results are in agfeement with the general results expected based on

previous research studies. According to reports by Thomas ’74)and Cartledge, et

al.(75), the mechanism of lead stabilization is s/s wastes is by solubilization and

reprecipitation as the pH fluctuates throughout the cement hydration reactions.

Cocke and Mollah ’76)also point out that lead species are reprecipitated onto the

surfaces of cement particles, making them more available to leaching fluid.

An analysis of the shake extraction test Ieachate for lead indicated that the

concentration of lead present in the Ieachate decreased from day 1 to year 2 for all

samples. It should be noted that the shake extraction test analysis was not

completed during the interim between the day 1 and year 2 analyses. As noted in

the Figure6 below, the pH range for the samples measured on day 1 was 10-11.

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46

However, the pH range for the samples measured at year 2 decreased to between

8.5 to 9. One explanation for the decrease in lead mobility maybe related to the

decreasing pH among the samples at year 2. If lead is indeed bound in its

hydroxide form, then its volubility can be compared with Figure 1, which;;~,/

demonstrates a decrease in the concentration of lead leached with decreasing pH.. :\

between 1d and 8. The complexity of the s/s waste systems for this study could. .

account for the differences in volubility in Figure 1 (which was developed for a

simple aqueous system).

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5.1.4 Zinc

Analysis of the TCLP Ieachate for zinc for the six samples indicated that zinc

mobility varied for e$ch of the s/s wastes examined. Figure 7, which follows, shows;>?/

the results of the TCLP Ieachate analysis for zinc with time. For most of”the,. :\

samples, the concentration decreased between day 1 and day 90, however, in two

of the samples, the concentrations increased at 2 years. The remaining samples

showed a slight decrease or exhibited the same concentration of zinc in the TCLP

Ieachate after two years. Studies by Cocke and Mollah ’77)and by Peon and Perry

‘7s)suggest that zinc is deposited as a mixed hydroxide and adsorbs to the surface

of cement grains. Given this mechanism, combined with the acidic pH of the TCLP

leaching fluid, it maybe expeded that zinc would readily leach from the s/s wastes.

However, the TCLP leaching test results for the samples examined in this study do

not wholly support this notion.

Interestingly, the shake extraction test Ieachate analyses for these six

samples indicate that the concentration of zinc in the Ieachate increased from day

1 to year 2. Figure 8, below, shows the zinc concentration in the shake extraction

test Ieachate with time. As was the case for lead, no intermediate shake extraction

test analyses were completed cm these samples between day 1 and year 2. As

noted in the figure, the pH range for the samples measured on day 1 was 10-11.

However, the pH range for the samples measured at year 2 decreased to between

8.5 to 9. One explanation for the increase in zinc mobility may be related to the

50

decreasing pH among the samples at year 2. If zinc is indeed bound in its

hydroxide form, then, according to Figure 1, it may be noted that the leftmost potiion

of the Zn curve is applicable in this system. The complexity of the s/s waste

systems for this study could account for the differences in volubility and pH range;;~,/

in Figure 1 (which was developed for a simple aqueous system).~. .-\

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6.0 SUMMARY AND CONCLUSIONS

Though solidification/stabilization technologies are increasingly used to treat

a variety of hazardous wastes, little research has been conducted to examine the;’,,~../

permanence of metal immobilization in the s/s wastes. This study was conducted‘Y

to evaluate ~he long-term leaching characteristics of cadmium, chromium, lead and. .

zinc from metal-laden. wastes treated with Clean-Coal Technology by-products.

Prior research conducted at the University of Pittsburgh, which serves as the

foundation for this study, has Ibeen described and noted in the report. The

conclusions of this study are summarized in the following bulleted items below.

b Cadmium and chromium, as measured in TCLP Ieachates of the six samples

considered in this study, remained immobilized after two years curing time.

The concentrations of cadmium chromium in the TCLP Ieachates from day

1 to year 2 remained below the current BDAT standard of 1.0 mg/L and 5

mg/L, respectively. These results are in agreement with previously published

studies cited in this report which suggest that cadmium and chromium are

tightly bound within the s/s matrix.

b The immobilization of lead and zinc within the s/s matrices varied among the

six samples considered for this study. The lead concentrations in two of the

samples were slightly above the BDAT standard of 5 mg/L for lead after two

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years. Concentrations

increase after 2 years.

54

of zinc in the TCLP Ieachate did not significantly

h In general, the leaching test analyses provided information about the;z~/

leaching characteristics of cadmium, chromium, lead, and zinc in the”six~. -\

samples examined for this study and the results were consistent with

previously published studies. However, an explanation of the mechanisms

by which these metals were immobilized within the wastes could not be

determined without the use of microscopic techniques for evaluation of the

changing mineral phases present in the s/s wastes.

b Also, the results of the

Technology by-products

chromium after two years.

TCLP analyses indicate that the Clean Coal

are effective in immobilizing cadmium and

Though the concentration of lead in the TCLP

Ieachates of two of the six samples studied exceeded the BDAT standard

after two years, the result is not significant enough to discount the

effectiveness of CCT by-products for lead stabilization. Also, the CCT by-

products were effective in immobilizing zinc after two years. Though zinc is

not currently a RCRA-regulated metal, the concentrations of zinc in the TCLP

Ieachate after two years did not significantly increase as compared to the

one day measurements.

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7.0 RECOMMENDATIONS AND SUGGESTIONS

55

FOR FUTURE RESEARCH

In order to improve the present study, TCLP analyses of the six samples

could have been ~erformed multiple times in order to determine a mean and& /

standard deviation for the conc&trations of the metals in the TCLP Ieachates. This“\

suggestion would help to verify the results of the present study, and insure that the. .

results were not based on the measurement of a “hot spot.” In addition, other

methods for analyzing the samples, including leaching tests and microscopic

analyses could have been completed in order to better characterize the changes in

metals leachability with time. I+owever, long term stabilization issues were not

within the scope of the original project begun at the University of Pittsburgh, and

these methods of analysis were not conducted on the samples at day 1. Therefore,

no comparison could have been made with the two year samples, had these

analyses been conducted.

The issue of long-term stabilization/solidification of metals contaminated

wastes, though not presently important in decision-making scenarios, is extremely

relevant with regard to liability for the disposers of these materials.

Solidified/Stabilized wastes are known to continue to undergo solid phase chemical

reactions after the initial set of the material is achieved. With these reactions, come

changes in the mineralogy of the sample, causing changes in the microstructure,

and subsequently, changes in the leachability of the hazardous constituents. The

focus of s/s research is beginning to shift toward identifying the solid phase

56

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reactions occum”ngin the waste matrix in order to evaluate long-term effectiveness

of s/s technologies. Experiments which provide information about the mineral

phases present in the waste matrix, and the changes in the mineral phases are

needed to characterize the effects of aging and weathering on sls wastes.:;~,/

Chemical and mineralogical analyses, using various microscopic techniques, will aid.’\

in understanding the chemical and mineralogical changes occurring as the s/s. .

waste weath&s..’ ‘

In addition, analysis of the durability of s/s wastes should be completed on

field samples wherever possible. Environmental factors which affect the weathering

of s/s wastes are site-specific, therefore field studies of weathered samples would

give better information on the effects of weathering than would simulated

weathering tests completed”in-the laboratory. As well, the development of leaching

tests to better characterize the durability of s/s wastes overtime are needed, as the

TCLP test was not designed for that purpose.

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. .. APPENDIX A

57

58

CLEAN-COAL TECHNOLOGY BY-PRODUCTS

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The following section summarizes the processes by which the Clean-Coal

Technology by-products, used as stabilizing agents in the prior study, are formed,;,?/

as well as the geoche,mical and reactive properties of each of the CCT by-products

used. ‘ . ..,i $. ..

CCT By-product Formation Process

In dry CCT systems, a calcium-based sorbent (usually slaked lime,

limestone, or dolomite) is injected directly into a furnace, ductwork, precipitator, or

scrubber vessel that produces powdered or granular by-products, as opposed to the

slurries associated with trad~onal wet scrubber systems. All these processes

produce a by-product which is removed in the particulate control equipment. Dry

by-products from lime or limestone injected into the furnace, such as in fluidized bed

combustion (FBC) systems, have neutralizing, sorptive, and cementitious properties

that make them interesting as potential reagents for hazardous waste stabilization

because of their high quicklime (CaO) and anhydrous calcium sulfate (CaSOA)

contents. The specific composition of a particular type of by-product may vary

widely depending upon the CCT process employed, the coal and sorbent

composition, and the plant operating conditions.

The three CCT by-products used in this study each originate from slightly

different CCT processes. The Spray Dryer Residue is collected from the outlet of

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a pulverized coal boiler unit burning high-sulfur eastern coal. The Pressurized

Fluidized Bed Combustor (PFBC) Residue originates from a process in which

dolomite is burned in a high pressure furnace. The Circulating Fluidized Bed

Combustor (CFBC).Residue originates from a process in which coal waste is fed to;;~/

a boiler, resulting in a relatively coarse by-product material..,

. .

CCT BV-Prodtict. Char%icterizatio~

Three CCT by-products were utilized as the stabilizing agents for this study.

The by-products

summary of the

were collected and characterized by a local lime company. A

geochemical and reactive properties of each of the CCT by-

products is presented in Table Al.

The geochemical analysis of the three CCT by-products provides information

on the types and amounts of inorganic compound present in the materials.

Pozzolanic compounds, such as Si02, AlzO~,and F~O~, which are commonly found

in fly ash, provide desirable characteristics for waste treatment. In addition, the

amount of free lime (CaO) in each of the three by-products is significant. The

presence of these materials in the binding agent allows the formation of metal

hydroxides, oxides and silicates as an important S/S mechanism. The noticeable

amount of sulfur present in each of the three by-products is expected, since sulfur

sorption was the primary goal of CCT processes. The presence of sulfur in treated

waste mixtures has been proven to be detrimental to the long-term durability of the

waste material, and play a significant role in the leachability of contaminants from

60

the waste material.

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In addition to the geochemical characterization of the CCT by-products,

several parameters related to the reactivity of the materials were evaluated. The

available lime inde~ is an important variable which provides some indication of the;,?,/

amount of lime able to react. “Incomparison to the amount of free lime in each of‘\

the CCT by~products,the ,amount of lime available for reaction is significantly less.

The pH values of the’three by-products are similarly high, indicating that the by-

product materials are highly alkaline.

Tabie Al Mean Comparison of CCT By-Product Properties

Geochemical Analysis (Y.) Spray Dryer Residue PFBC Residue CFBC Residue

CaO..

28.91 20.94 10.61

MgO 0.70 ?2.89 1.26

Si20 20.18 21.75 48.56

Fe,O, 6.39 10.78 6.92

A120~ 10.24 9.39 18.45

Total Sulfur as S 10.03 4.47 2.3

Reactivity

Available Lime Index (Yo) 3.7 0.9 4.0

pH 12.36 11.92 12.52

A comprehensive metals analysis of each of the three CCT by-products was

performed prior to the start of this project and is summarized in the theses by

Clifford and Pritts cited previously.

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Table BI TCLP Extracts - Cadmium Analysis

Time Current BDAT Future BDAT Munitions Soil WWTP Soil VVVVTPSoil Munitions Soil Munitions Soil Industrial Soil

(days) Standard Standard WI 10O?40EPC WI50’?40EPC WI50?40Tidd WI 50% Tidd VII50% Consol W/ 50?40Tldd

1 ,1 0.19 ND ND ND ND” ND ND90 1 0.19 0.02 0.01 0,01 0.01,. 0,02 ND730 1 0.19 0,05 0,02 0.03 0.04 0.03 ‘ 0.03

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Time Current BDAT Future BDAT Munitions Soil WWTP Soil WWTP Soil Munitions Soil Munitions Soil Industrial Soil(days) Standard Standard WI 100% EPC WI 50% EPC WI 50% Tidd WI 50% Tidd WI 50% Consol WI 50% Tidd

1 5 0.86 ND ND 0.16 ND ND ND90 5 0.86 0.18 0.18 0.02 0,05 0.24 ND

730 5 0.86 0,27 0.03 0.04 o.d4 o.o~ 0.01 ‘

ETime(days)

190365730

iiA14&—ti ————— 1?—> ,— — L—.J— —.. ,.-, ..,. — -.. — --- -. .

Current BDATStandard

55

Future BDATStandard

-0,370.370.37

Table B3 TCLP Extracts - Lead Analysis

Munitions Soil WWTP SoilWI 100% EPC WI 50?40EPC

4,3 0.189.03 5.96nla 0.65

5.59 0.33

%YkPk%YWWTP Soil w/ Munitions Soil Munitions Soil

0.56 I 1:21 I 0,871.12 1.74 1.0’70:75 I ., 1.25 I “ 2.17

Table B4 Shake Extraction Test - Lead Analysis

Time ‘un’t~onsII

Soil WI 100%‘VVWTPSoii “VVVVTPSoii Munitions Soii

(days)EPC

WI 50% EPC WI 50% Tidd w/ 509f0Tidd

1 0,56 0.94 0.34 0.15730 0.09 0 0.01 0

i 1

Muniticms Soii Industrial Soii “ww/ 50?10Consol 50% Tidd

=%Fq=$q

Industrial SoilWI 501X0Tidd

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Table B5 TCLP Extracts - Zinc Analysis

Time Current BDAT(days) Standard

ETime(days)

1730

Future BDATStandard

5.35.35.3

Munitions Soilw/ 100% EPC

1.80.323.59

WWTP Soil WWTP Soil Munitions Soil Munitions Soil WI Industrial SoilWI 50% EPC WI 50?40Tidd WI 50% Tidd ,50?40Conso! w/ 50?40Tidd

0.1 1 0.1 “ 5,1 2.40.26 0,08 0.23- 0.56 1.10.27 0.21 0.39 0.09 A 1.09

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Table B6 Shake Extraction Test - Zinc Analysis ~

MunitionsSoil WI 100%

EPC0.070.2

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0,03 0,020.21 0.25

MunitionsSoil WI50%

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. > APPENDIX C

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68

USING THE PERKIN-ELMER 11OOB( M SPECTROPHOTOMETER

L Sign in the logbmk It is on the bench by the instrument.~~,,/

2. Flip open cover for the limp holder. Check to see if a lamp(Cu) is in position. Ifnot place a lamp (CU) into the holder and rotate turet into the proper position (lampshines through sample compartment).

,.

3.Tum #ow~ switch on. It is located at the bottom left comer of instrument.

4. Wait for the computer to run the initialization test (a couple of minutes). Thecomputer screen will display the ElementSelectMode page &@re 1.) when done.

5.At the bottom of the screen, there are options listed in rectangles. They areactivated by the grey soft function keys located on the top row of the key pad (13gure

6).

6- Type in the date in the follow format, 951025, then press the DATE soft functionkey. .-

7. Place lamp into holder and turn the turet until in proper position (where the Culamp was). Next plug in lamp in either the HCL 1 or HCL 2 (If using a non-codedlamp an adapter must be used). Make sure the Lamp soft function key is set tothecorresponding lamp connection. The Lamp fimction key toggles between lamp 1 and2-

8. Type in the element number (If a non-coded lamp is used), then press theELEMENT soft key. Xfusing a coded lamp the computer will know what is there andwill display the “cookbook” parameters.

9. Type in the appropriate current (mA) and press the L.CURR soft key. Generally,this is 2 or 3 mA lower than the maximum current list on the lamp.

Settim? UD thesrm3roDhotometerandalismin$ztheIamD:

L Press the SETUP fimctionkey. The functionkeysarewhiteand arebated on theleft-handsideofthekeypad.

2.The computer wilI automatically setup the wavelength to be monitored for thespecific element chosen. Doubie check that it is the right wavelength. The monitorshouId look like Figure 2.

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69

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L Turn on the f% fm thehood behind you....

2.Turn on tie ai.r~The v&e is on the right side of the hood.

3. Turn on the acetylene (short tank). The pressure should be set to 13 psig (-rabove 15 psig).

4. Press tie F’IAklE key (red).

5. Watch the air gauge when the flame ignites.psig for proper operation-

6. Wait 20 min. for the sj%em to equilabte.

The linepressure should be 57-59

~edtin~ DUtitY and Sensitivim

1. Press the CONT fixriction key. &reen should look ~ figUre 3.

2. Place a beaker of D.L water onto the sample tray and insert sampling tube intoIiqui&

3. Pressthe A~O-ZERO softkey. The instrument is now zeroed. It should takeabout 10-20 m.h for the lamp and flame to stabilize.

4. Measure the absorbance of one of the standards. Use the one with theconcentration ckxest to the sensitm“- .ty check concenkadon listed in the AA manual.

5.Ifthesensitivelyisnothighenough, you may have to change the fuel mixture forthe flame. To do so, press the ATOM CONTR function key. The lab instructorwillshow you how. Press theMAIN KEYS soft key to returnto continuous mode.

6. Measure the absorbanceof the qual@ control sample. Compare the two resultsand determine the purity (and correct concentration) of the standard.

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3. If backgroundcorrectionis needed,pressthe BG CORR soft key.

4. Next align the lamp and maxhnke the energyout pu~ Tim lab instructorwillshow you how the first time.

5. Record the Iampeiemen~ energy, currenGand other Morn@on requestedin thelog book. --

Lkhtirw the ffiime:

L Turn on,the I%,, ●..

2.Turn on the air.

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for the hood behind you.\

.The valve is on the tight side of the hood.

3.Turn on the acetyiene (short tank). The pressure shouId be set to 13 psig @everabove 15 psig).

4. press the FLAME key(red).

5. Watch the air gauge when the flame ignites. The line pressure should be 57-59psig for proper operation.

._

6. Wait 20 min. for the system to equilabxate.

Checkixw DUlitV and sensitiviw:

1. Press the CONT function key. Screen should look like figure 3.

2. Pi.ace a beaker of D.I. water onto the sample tray and insert sampling tube intoliquid.

3. Press the AUTO-ZERO soft key. The instrument is now zeroed. It should takeabout 10-20 min. for the lamp and flame tostabilize.

4. Measuretheabsorbanceof one of the standards. Use the one with theconcentrationclosest to the sensitivitycheck concentrationlisted in the M manual.

5. If the sen$tivi~ is not high enough, you may have to change the fuel mixtureforthe flame. To do so, press the ATOM CONTR function key. The lab instructorwillshow you how. Press theMAIN KEYS soft key to returnto continuous mode.

6. Measure theabsorbance of the quality control sample. Compare the two resultsand determinethe purity (and correct concentration) of the standard.

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X. Press tbe PROG tiedon key. Scteen should look like figure 4.

2 Selupipefollowingparam-,Rd’ -y (S@: ~-Oz~,jPrintec ‘Data +Cai

,. ~ 5v standardUnitx mg/L

sampleUr@!x mg/L

‘..3. &m&ntrationof tie standardsareenterednexL S1 isthefirststandard,S2 thesecond and v forrh. The number of decimal pkicesusedincateringtheconcentrationof thestandardswilldemminethenumbtiofdecimalpiacesdisplayedbytheoutput(i.e.5.00wilIgive2 decimalpiaceoutput).

4.Atthispointtheptintercanbeturnedonby pressingthePRINT functionkey.PressthePRINTER OIWOFF softkeytoactivatetheprinter.PresstheWKEYS SO~KEYS toreturntotheprogrammode.

5. Press the RUN fimction key. Screen should look W figure 5.

6. The &t soft key is-the AUTO-ZERO. Press this key at anytimeyouwanttozerotheSpectrophotometer.

7. Press the STD 14 soft &y. PIace the stan&rd On the sampletrayandputthesample tube into the Iiquid. Press the STD X soft key (X is the appropriate standardcuxently beingmeasured,k. 1,2 etc.)

8.. Rqx=t.forallslandards. When the last standaxd has been run a ealibxation curvewnll be pmted out..

9. Samplesshould be measuredinthefollowingordera.Qualitycontrolsampleb.Blankc- samples(max20)d-Spikedsamplee.Spikingsolution

10.Place sampleonkayandputsampietubeintoliquid.

11.-PressREAD functionkey(blue).

~. Repeatforeachsetof20 samples, s@xingwith a calibmtion ch~k. Always endwith a calibrationcheck.

72

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Figure 7-1. Spect.rc.meter Keyboard

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Figure 3.

a 9.UZ 1* ..488

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—--n R —aw*-

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-anmrmcu fwc Mm #78wi4-. $s —m -). =.. Y,Ir <no,●.? “ 1

EIEIFEslrlnnEl )Figure 4.

1

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“Figure 6.

74

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.- APPENDIX D

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QUALITY ?K3SURMCE PROJECT PLAN

FOR.

TREATMENT OF ti2i.-LADEN EAZARDOUS~TES WITH ADVANCED CLEAN COAL

TECHNOLOGY BY-PRODUCTS

Awa;d Number DE-FC21-94MC31175. ...

“ Center for Energy ResearchSchool of Engineering, University of Pittsburgh

Submitted to:

Us. Department of Ene~gy - Morgantown Energy Technology Center

Septemberr 1994

by:

James T. Cobb, Jr.

Center for Energy ResearchUniversity of Pittsburgh

Pittsburgh, PA 15261

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1.0

2.0

3.0

4.0

5.0

6.0

7.0

8-0

9.0

10.0

11.0

12.0

13.0

14.0

15.0

16.0

Sukksa

TITLE PAGE

Z!ABLE OF commrs

PROJECT DESCRIPTION;,~,/

PROJECT ORGANIZIUION.. .’\

\4.01 Specific Project Responsibilities

QA OBJECTI& FOR MEX UREMENT DATA.,.SA&ING PRO&DURES

CALIBRATION PROCEDURES

ANALYTICAL PROCEDURES

8.01

8.02

DA’J!.A

9.01

9.02

Leachate Testing

Metals Analysis

REDUCTION AND REPORTING._

Metals

Reduction and Reporting Data

INTERNAL QUAL12!Y CONTROL CHECKS

10.01 Metals

PERFORMANCE AND SYSTEM AUDITS

PREVENTIVE MAINTENANCE PROCEDURES AND SCHEDULES

SPECIFIC ROUTINE PROCEDURES USED TO ASSESSPRECISION, ACCURACY AND COMPLETENESS

CORRECTIVE ACTIONS

QUXJTY ASSURANCE REPORTS TO

REFERENCES

MANAGEMENT

76

2

3

3

3

4

8

9

9

.9

9

10

10

11

13

13

14

14

15

17

19

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3.0 PROJECT DESCRIPTION

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The research project to which this QA/QC proposal relates

has been described in the proposal, “Treatment of Metal-Laden

Hazardous Wastes with Advanced Clean Coal Technology By-.

Products”. The objective of $@is research is to evaluate the

stabilization of-ten commercial hazardous metal-laden solid\

wastes with by-products from four ad~ced coal technology

:,,combustion/destilfurization.

4.0

4.01.

PROJECT ORGANIZATION

a) Principal Investigator: Dr. James Cobb

i) Overall coordination and oversight of the project

in its-entirety.

b) Environmental Engineer: Dr. Ronald Neufeld

i) Coordination ’of data storage, retrieval,

manipulation and graphical presentation of all

analytical data; and,

ii) Validation and

from the above

c) Laboratory Manager:

presentation in final form of data

analyses.

Dr. E. M. Schreiber

i) Overall coordination of QA/QC activities;

ii) Organization and conduct leachate testing on

mixture of by-product and hazardous waste;

iii) Organization and conduct of metal analyses and of

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v)

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QAA2C program;

Sample Custcldy, preservation and storage,

distribution and disposal;

Equipment mntit=mce, procurement of supplies and

equipment and f~gilitation of outside semri.ce;,,. ,

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5.0 QA OBJECTIVES FOR MEASUREMENT DATA

The QAi;obj.ectives for precision, accuracy and completeness

of the measurements made during this research project are

presented in Table 1. All results will be expressed in metric

units - usually milligrams per unit volume or mass.

a) Accuracy: Accuracy is a measure of the correspondence

between the analytical measurement and an accepted

reference or “true” value. The accuracy goals of this

project will be addressed by the use of reference

materials of the highest purity, for method calibration

and sample spiking and by incorporation of frequent

reference samples into the analytical stream. The use

of spiked samples permit a constant check on method

accuracy and will provide an indication of the degree

of matrix effect. This be expressed in terms of

percent recovery.

(Spiked sample) - (Unspiked Sample)% Recovery = _ x 100

Spike

This value will be calculated for all spiked samples.

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TABLE 1. SUMMARYOF PRECISION ACCURACY AND

79

coMPIJmmEss

Measurement Reference Precision Accuracy MiJlimumStd. Dev. Completeness

.

As Direct A.sp@at. ;@/-lO% 90-110% 90%Perkin-Elmer

.. Applications

(where s;ple~w~~~ent lower detection limits)., Hydride Method‘ @ariti Instruct.

Manual +/-10% 90-110%

Cd EPA SW-846 +/-10% 90-110%Method 7131

Cr EPA SW-846 +/-10% 90-110%Method 7190

Cu EPA SW-846 +/-10% 90-110%Method 7210._

Hg EPA SW-846 +/-10% 90-110%Method 7471

Ni EPA SW-846 +/-10% 90-110%Method 7520

Pb EPA SW-846 +/-10% 90-110%Method 7420

Se Direct Aspirat. +/-10% 90-110%Perkin-El.merApplicationsManual

(where samples warrent lower detection limits)Hydride MethodVarian Instruct.Manual

Zn EPA SW-846 +/-10%Method 7950

90-110%

90%

90%

90%

90%

90%

90%

90%

90%

90%

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b) Precision: Precision is an index of the a~ent

among individual measnxremants of an identical sample

parameter. The precision for these studies will be

measured in term of the standard deviation(s) of

replicate neasuremen~<~;

and/or critical ~rge

R= = the

c) Completenesss:

of valid data

largest

n-l

(R=) :

of the K: - the smallest of the Xa

-Completeness is a measure of the amount

collected as compared to the amount

expected within the constraints of the operation and

sampling program. It is a function of two factors.

i) SampLes collected but not analyzed;

ii) Data

Since all

subjected

rejection

rejected following validation procedures.

samples collected are expected to be

to the intended analyses and since the data

rate is anticipated to be well. under 10%,

completeness will be s 90% for all analyses.

d) Representativeness: Representativeness is a measure of

the degree to which the data accurately and precisely

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represent

levels of

nature of

carefully

the systenr under study. TO

representativeness in these

81

attati accept~le

studies, the

the samples collected will be

e-uated with respect to homogeneity y anti

relationship to the conditions pertaining in the

landfill test cells. ““K addition, careful protocols .Of.. -\

sample collection, storage and presemation will be

+.,

e) Co~ajabiL~ty:

importance when

*alyses passes

times.

Comparability will be a factor of

the responsibility for specific

from one analyst to another or is given

to more than a single analyst. This factor will be

addressed by subjecting each anal.yst’s technique to a

care~~l statistical eva~uation using pure reference._

samples and spiked samples.

data assuring continuity and

derived.

6.0 SAMPLING AND SHIPPING PROCEDURES

From these evaluations

comparability will be “

E’aculty,graduate students, and project manager from Pitt

will visit the Yukon Plant of Mill Sezxrice. The graduate

students will obtain samples and prepare cylinders for

compressive test strength testing and leachate testing. Fo&y

cylinders will be prepared during each trip, comprising a SaIfLpk!

set. The cylihciers will be transpofied by ground vehicle to

Benedum Hall, University of Pittsburgh and an identification will

be number assigned to cylinders, and recorded in sample log book.

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7.0 CALIBRATION PROCEDURES

The calibration of aU laboratory equipment used

studies will be performed in accordance with stamdard

procedures as specified by tis&&nt manufactures or

in these

operational

by accepted

standard ~alyti.ca’~ methodologies and protocols as presented in

EPA manuals.. .

...

The calkiatio’n procedures in this effort will be those

specified in the analytical procedures list in Table 1 of this

Quality Assurance Puoject Plan.

All instrumental systems used will be fully calibrated in

accordance with the referenced methods (Table 1) at the beginning

of an analytical run. Recalibration will follow naturally as a._

consequence of the inclusion of quality control check standards

among the samples run.

Calibration standards will be obtained from commercial

sources or prepared using the highest quality prtiary standard

reagents. In all cases, manufactures’ lot numbers will be

recorded in the sample log book and referenced in all associated

analytical procedures-

8.0

8.01

ANALYTICAL PROCEDURES

All of the analytical methods used axe listed in Table 1.

Lea~te test.

Two leaching test procedures will be used;

1) TCLP, method 1310, SW-846

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2) ASTM, method D3987.

8.02 ~ - The EP extracts obtained from the TCLP and ASTM

leaching procedures will be digested in accordance will EPA SW-.

846 Method 3010 with the excep@on of As, Se and 13g. *senic,

Selium and Mercu~ will be digested\

in Table 1. ..

The me~al~ will be measured by

according the methods cited

atomic absorption

spectrometry using’ the methodology presented in Table 1. Direct

aspiration analyses will be performed on metals using a Perkin-

Elmer Model 11OOB AA spectrophotometer. Commercially available

certified standards

working standards.

method. Selium and

procedures found in

will be used to determine the purity of the

Mercury will be analyzed by the cold vapor

-“sSnic will be first analyzed by flame AA

the Perkin Elmer AA instruction manual.

Because the detection limits for these two metals is close to the

regulatory maxium concentrations for toxicity characteristic, the

hydride method will be substituted. The method described in a

Varian application note, “Some

Generator” will be followed.

9.0

9.01

DATA UCTION REPORTING

Metals

Studies with a Varian-76 Hydride

The metals will be analyzed in accordance with the

procedures outline above for other inorganic parameters. Metal

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concentrations will

The and metals

be reported in mg/L.

data will be repotied

84

to the principal

investigator. Results will be validated based on obsezwed and

expected trends and on internal QC checks. The data will also be-.

subject to validation during q,petings of the research team during

which all..results-xwill be reviewed.\

9.02 ReDo*ma.

and of Data

ALL fu&@ental analytical data collected (absorbance

readings, peak heights, etc.) will be recorded in

notebooks, and/or filed on, computer disks or hard

along with associated analytical information such

laboratory

copy output,

as calibration

data, reagent concentrations, and sample dilutions. These

analytical data will then be reduced to the ultimate reporting by

appropriate procedures’. ‘Internal calibrations, methods i= which

the instrument has been calibrated to yield data directly in

appropriate reporting units by use of one or more standards will

be used with the Atomic absorption spectroscopy of metals.

85

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Analysts: Data Storedin Computer for Pro- -------------- --—

cessing and Retrieval

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Validation ofMetals Data

II f RecommendationTeam Validation

of Data Management Group

Figure 4. Validation Sequence for Data

.

)

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ITABLE 3. EQUATIONS AND REPORTING UNITS FOR ANALYTICAL

PARAMETERS

b

86

Parameter: Metals # / Reporting Unit: mg/L

Method: ~ Direct Aspiration Flame AA

Reference: USEPA SW-846

Equation: “! .“Method 7000, Section 7 .4.2

xug/L in sample = A * (C + B) / C

Where;

A= mg/L of metal- in diluted aliquot from calibration curve;

B.fief

C.fief

deionized distilled water used for dilution;

sample aliquot

10.0 INTERNAL QUALITY CONTROL CHECKS

10.01 J$etala

Quality control procedures for metals will be consistent

with methodology presented. in EPA SW-846. In this regard, the

following strategies will be followed:

a) The AA spectrophotorneter will. be calibrated by use of

standards prepare in the lab which the purity has been

previously checked with a certified commercial standards.

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b) One sample in four (25%) will be run in replicate.

Agreement within 3 of the mean will be required on all

replicates.

c) For every five samples analyzed, a water blank and blank.

spiked with a known mixtzw= of =tals will be =a~yzed- The

percent recotiery will be calculated for each metal..

Recov’eriesshould be within 90-110%.

d) ‘“’;Fazlufe to attain the criteria in either steps (b) or

(c)above will’ be cause to repeat the entire set of metal

analyses.

PERFORMANCE AND SYSTEM AUDITS

In cooperation with the sponsor, a complete Syst- audit

be carried out as deemed appropriate by the sponsor.

The QA/QC strategy outlined previously will assure that

ongoing performance audits will be maintained.

12.0 PREVENTIVE MAINTENANCE PROCEDURES AND SCHEDULES

Preventive maintenance will be conducted on all instruments

at a minimum frequency as specified by the manufacturers of the

instrumentation. In addition, more frequent maintenance will be

conducted if

complete log

instrument.

the age, condition and level of use dictate. A

will be maintained of all such activity for each

Beyond a selection of standard electronic parts - resistors,

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88

capacitors, etc. - no extensive supply of replacement parts will

be kept on hand. The University of Pittsburgh’s location in a

major metropolitan area pexmits rapid emergency setice and

acquisition of replacement parts from local sources.<

Furthermore, a significant poq@ion of instrument se-ice will

entail simple replacement of circuit boards, parts which will not

be commonly kept on hand by instrument users, but which can be:,,

rapidly acqu+reti and installed. It is unlikely that any but the “

most extreme of instrument failures will entail a down-the of

more than 48 hours on any instrument.

13.0 SPECIFIC ROUTINE PROCEDURES USED TO ASSESS PRECISION, “

ACCUI#.CY AND COMPLETENESS

Since the volume bf--si~ples to be analyzed during the course

of the investigations precludes the analysis of replicates of all

samples, the following methodology will be used to monitor

precision and accuracy.

a) During the initial phases of the study, all analytical

methodology will be subjected to a statistical evaluation using

known standard samples. The object of this evaluation will be

the establishment of levels of precision and accuracy expected

for each method. The standard samples will be selected to cover

the ranges of values anticipated for the actual samples.

In all cases, the analyst whose responsibility will be the

routine measurement of the specific parameter under consideration

89..-

wiU conduct the analyses for this statistical evaluation.

b) CIXZtrOLdtartswill be ~~s~ f- ~ reFetit~=

-ysis of - acceptable ~~1 ~~ - me ~~1

criterion will be 3 units . The control chart will contain the

tistmmental re+oxlse plotted over time over time.>?/

c) Sticepr~sion &d accuracy will be subject to the .

technique of the specified analyst, any change in analyti.-l

personnelwill necessitate a re-etiuation of< +. -.

method and generation of a new contzml chart.

ene -al yst be allowed to use a cozz~=l chart

Once control charts are established, the

the analytical

In no case will

by another analyst.

routine inclusion

of spiked samples, contzol standards and sample replicates will

permit evaluation of means, ranges and relative standard

deviation which can he used b t~= to assess accuracy axd also

be compared by use of &t~tisticaL prOCedL-eS SuCh as me t tes~-

CompLeteness will be e-lusted by means of accurate S@le

loggbg and trackfig so that the ratio of acceptable analyses to

the number of samples drawn may be determined.

14.0 CORRECTIVE AC’I!ZONS

Corrective actions h response to obsemed deviations of

analytical methodology from speci:ied control criteriawill be

taken on the basis of the nature of the method.

a) Me-: h Routine inst.-ent maintenance and

cl.eani~g and preparation of new standards followed by

recaI.ibration should alleviate the bulk of problems in purely

instrumental techniques. Only k the most extreme

inte~ention of se~ice personnel be required.

b) ~: Since metaJ. analyses involve both

cases will the

an elaborate

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wet chemical technique (digestion) and instrumental method,

analytical probl~ may entail elements of both. The use of a

clean standard should serve to localize the

or instrument - after which the appropriate

will be taken. ‘ ;,?,/

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problem - digestion

corrective action

15.0 QUALITY ASS-C3T REPORTS TO MANAGEMENT..

Data aqses.,smeptwill be conducted by the project

investigators on a’continuing basis. The following reports will

be in fulfilling QA responsibilities:

a) A report will be made following performance audits.

This will be included in the subsequent progress report.”

b) A section describing all QA activities and results will

be included in the-final project report.

The Quality Assurance Reports will include the following

components, where appropriate.

a) Modification of the existing Quality Assurance Project

. . . Plan and rationale underlying such modifications.

b) Any limitations o:rconstraints on the applicability of

the data and proposals regarding their elimination.

c) The current status of quality assurance programs and

accomplishments and the status and outcome of corrective

actions taken.

d) The results of any quality assurance system or

performance evaluation audits undertaken with respect to the

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analytical methodology.

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e) Updated assessments of the quality of the data in terms

of precision, bias, completeness, representativeness and

comparability, as appropriate..

f) Description of any p~~,gram of quality-related training

unciertaken in the course of research including the\

identification of the personnel involved and status and

outcomes .of these programs.

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16.0 REFERENCES

Test Methods for Evaluating SeLid Wastes, Physical/~-ical

Methods, U.S. EPA SW-.846, 1986 revision.

ASTM, Method D3987.

Model 11OOB Atomic Absorption Operator’s Manual, PerkinElmer, Release A2,,,Sept~er 1988.

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-_ BIBLIOGRAPHY

1.

2.

3.

4.

5.

6.

7.

8.

9.

10.

11.

12.

13.

14.

,,

94

IBIBLIOGRAPHY

Cullinane, M. J., and L. W. Jones. Stabilization/Solidification ofHazardous Waste. Cincinnati: U.S. Environmental Protection Agency(U.S. EPA) Hazardous Waste Engineering Research Laboratoy(HWERL), EPA/600/D-86/028, 1986.

Means, J. L., Smith, L. &,;Nehring, K. W., Brauning, S. E.,Gavaskar, A. R., Sass, B. M., ~les, C. C., and Mashni, C. l., The ~Am{ication of Solidification/Stabilization to Waste Materials, (Boca Raton,Florida: Lewis Publishers, 1995), p. 4.

. .

~heese~an, C. R., Sollars, C.J., and Perry, R., “Mechanisms ofMetal Containment Resulting from the Solidification of a CommerciallyProduced Stabilized Waste,” Stabilization and Solidification ofHazardous. Radioactive, and Mixed Wastes: 3rd Volume, ASTM STP1240, T. Michael Gilliam and Carlton C. Wiles, Eds., American Society forTesting and Materials, 1996.

Gilliam, T. M. And Spence, R. D., “Development of Cement-BasedGrouting Technology: A Perspective”, Proceedings of the FirstInternational Symposium on Cement Industry Solutions to WasteManagement, Caiga~,-Alberta, Canada, pp 45-53, October 7-9, 1992.

Conner, J. R., Chemical Fixation and Solidification of HazardousWastes (New York: Van Nostrand Reinhold, 1990), p. 25.

Ibid., p. 26.

Ibid., p. 27.

Ibid., p. 3.

Ibid., p. 202.

Ibid., p. 204.

Ibid., p. 205.

Ibid., p. 30.

Means, Op. Cit., p. 154.

Lea, F. M., The Chemistry of Cement and Concrete, 3rd Edition,(Chemical Publishing, New York, 1970).

95

1

I 15. Adaska, W. S., ~resouthick, S. W. and West, P. B., “Solidificationand Stabilization of Wastes Using Potiland Cement,” Portland CementAssociation, (1994), p. 6-7.

16. Kosmatka, S. H. and Panarese, W. C., “Design and Control ofConcrete Mixtures,” EBOOOI, Portland Cement Association, 1990.

17. Adaska, Op. Cit., p. 7. ,Z,

18. LaGre~, M. D., Buckingham, P. L., and Evans, J. C., HazardousWaste Management (New York: McGraw-Hill, Inc., 1994), p. 648.

Means, Op. ‘Cit., p. 154.: .19.

20.

21.

22.

LaGrega; Op. Cit., p. 647.

IConner, Op. Cit., p. 31.

Bhatty, M. S. Y., “Fixation of Metallic Ions in Portland Cement,”Proceedings of the 4th National Conference on Hazardous Wastes andHazardous Materials, (Washington, D.C., 1987), p. 140-145.

23. U.S. Environmental Protection Agency. Federal Register: 52(155):29999 (August 12, 1987).

124. Treatability Studv Manual: Solidification/Stabilization, (Valley

Forge, Pennsylvania: The PQ Corporation), p. 11.

25.

26.

LaGrega, Op. Cit., p. 650.

Treatability Study Manual: Solidification/Stabilization, Op. Cit.,

Treatability Studv Manual: Solidification/Stabilization, Op. Cit.,

I p.18.

p.17.27.

I. 28.

29.

30.

Conner, Op. Cit., p. 33.

Conner, Op. Cit., p. 34.

Klich, Ingrid, “Permanence of Metals Containment in Solidified andStabilized Wastes” (Ph.D. Dissertation, Texas A&M University, 1997).

Brookins, D. G., Eh-~H Diaarans for Geochemist, (Springer-Verlag, New York, 1988).

‘1 31.

.:!

96

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4

<.

32.

33.

34.

35.

36.

37.

38.

39.

40.

41.

42.

43.

44.

Dragun, J., “The Fate of Hazardous Materials in Soil,” HazardousMaterials Contr. (May/June 1988), p. 41-65.

Bhatty, Op. Cit., p, 141.

Klich, Op. Cit., p. ;33-42.

Cocke, D. L. and Mollah, M. Y. A., “The Chemistry and LeachingMechanisms of Hazardous Sut$~tances in CementitiousSol~dification/~tabilization Systems,” Chemistrv and Microstructure of”Solidified Waste Forms, edited by R. D. Spence ( Boca Raton, Florida:Lewis Publishers, 1993), p. 24.

...

Peon, C;”S. and Perry, R., “Studies of Zinc, Cadmium, and MercuryStabilization in OPC/PFA Mixtures,” Materials Research SocietvSvposium Proceedings, Vol. 86, (1987), p. 76.

Ibid., p. 76.

Cartledge, F. E., Butler, L.G, Chalasani, D., Eaton, H.C., Frey, F.P., Herrara, E., Tittlebaum, M. E. and Yang, S., “ImmobilizationMechanisms in Solidification/Stabilization of Cd and Pb Salts UsingPortland Cement Fixing Agents,” Environmental Science and Technology,vol. 24, No. 6 (1990), p. 871.

Ibid., p. 871.

Cocke, Op. Cit., p. 202.

Cocke, Op. Cit., p. 202.

Kindness, A., Macias, A., and Glasser, F.P., “immobilization ofChromium in Cement Matrices,” Waste Management, Vol. 14, No. 1,(1994), p. 11.

Macias, A., Kindness, A., and Glasser, F. P., “Impact of CarbonDioxide on the Immobilization Potential of Cemented Wastes: Chromium,”Cement and Concrete Research, Vol. 27, (1997), p. 224.

Bonen, D. and Sarkar, S. L., “The Present State-of-the-Art ofImmobilization of Hazardous Heavy Metals in Cement-Based Materials,”Advances in Cement and Concrete, (ASCE, New York, 1994), p. 488.

.

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45.

46.

47.

48.

49.

50.

51.

52.

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53.

54.

55.

97

Thomas, N. L., Jameson, D. A., and Double, D. D., Cement andConcrete Research, Vol. 11, (1981), p. 143-153.

Cartledge, Op. Cit., p. 872.

Cocke, Op. Cit., p. 213.

Cocke, Op. Cit., p. 233.,P,

, Peon, Qp. Cit., p. 74-75.

Erickson, P., .M. and Barth, E. F.,’’Evaluation of ContaminantLeachability Factors by Comparison of Treatability Study Data for MultipleSolidified/Stabiflzed Materials,” Stabilization and Solidification ofHazardous. Radioactive. and Mixed Wastes: 3rd Volume. ASTM STP1240, edited by T. M. Gilliam and C. C. Wiles, American Society forTesting and Materials, (1996), p. 429-441.

Jones, L. W., Bricks, R. M., and Cullinane, M. J.,”Effects ofSelected Waste Constituents on Solidified/Stabilized Waste Leachability,”Stabilization and Solidification of Hazardous. Radioactive, and MixedWastes, 2nd Volume. ASTM STP 1123, edited by T. M. Gilliam and C. C.Wiles, American Society for Testing and Materials, (Philadelphia, PA,1992), p. 193-203. -

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