EPA/600/A-94/217
THE INTERNATIONAL ASH WORKING GROUP:
A STATE-OF-KNOWLEDGE TREATISE ON MSW INCINERATOR RESIDUES
S.E. Sawell1, A.J. Chandler2, T.T. Eighmy3, J. Hartlen4,
O. Hjelmar5, D. Kosson6, H.A. van der Sloot7 and J. Vehlow*
'Compass Environmental Inc., Burlington, Ontario; 2AJ. Chandler & Associates Ltd., Willowdale, Ontario;
3University of New Hampshire, Durham, NH; Swedish Geo technical Institute, LinkOping, Sweden;
JDanish Water Quality Institute, Hersholm, Denmark; ^Rutgers University, Piscataway, NJ;
^Netherlands Energy Research Foundation, Petten NL; and #Kernforschungszentrum Karlsruhe, Germany.
INTRODUCTION
Most municipalities in Europe and North America now face the difficult problem of managing the
ever growing volume of municipal solid waste (MSW) in an environmentally acceptable manner.
While an integrated strategy of utilizing the "4-R's" is regarded as the most efficient and cost
effective means of reducing the volumes of MSW requiring landfill, environmental groups have been
reluctant to endorse the use of all four "R's". Thus, an over-emphasis on recycling and firm
opposition to MSW incineration have resulted in a continued reliance on landfill, particularly in
North America.
Historically, public opposition to the siting and operation of MSW incinerators has been based on
concerns over emissions of contaminants to the atmosphere. During the late seventies and early
eighties, much of this concern was justifiable in light of the poor performance of inadequately
designed and operated facilities. In addition, the ability of scientists to detect trace contaminants at
very low concentrations placed further pressure on the industry to reduce emissions.
During the last decade, the industry has responded positively. Most of the concerns related to
emissions have been addressed by optimizing incinerator design and operation to improve
combustion control. This and the implementation of new air pollution control technologies has
dramatically reduced atmospheric emissions. The advent of more efficient incinerator operation and
better designed air pollution control systems has resulted in concern shifting from air emissions to
the disposal of the captured residues. Today, ash disposal is one of the major issues limiting the
acceptance of new incinerator facilities.
The Incinerator Ash Issue
In 1988 several individuals actively involved with ash research were prompted to suggest that the
global data base on incinerator ash needed to be compiled, reviewed and critically evaluated. In
North America, the major concern over incinerator ash centred on the potential for human exposure
to contaminants, specifically toxic metals in the ash. Exposure can occur either through the
inhalation of fugitive dust or the ingestion of contaminated groundwater. While the industry was
moving to address these issues, environmental groups continued to push for more stringent
regulations for the disposal of the residues. Several factors contributed to this situation:
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o The inherent variability of ash characteristics results in often contradictory laboratory results;
o Residue sampling and analytical protocols were not well established, thereby compounding the
variability of the data;
o Different combustion technologies and air pollution control systems produce additional
variations in the data base;
o Cursory groundwater studies provided an inadequate data base because the issue of potential
groundwater contamination through improper ash disposal had been considered minor for
many years; and,
o The management of these residues must consider the contentious issue of potential long-term
effects particularly in light of the changing nature of the waste streams.
All of these factors contributed to a highly fragmented data base which in turn has resulted in much
confusion and the propagation of many misconceptions. The researchers thought that a critical
review of the issues would provide an opportunity to clarify many of the issues. Thus, in April of
1989, a proposal entitled:
•MUNICIPAL WASTE INCINERATION: AN INTERNATIONAL PERSPECTIVE ON THE
CHARACTERISTICS, DISPOSAL, TREATMENT and UTILIZATION OF RESIDUALS"
was submitted to the International Energy Agency (IEA) for consideration and this led to the
establishment of an International Ash Working Group (IAWG).
OBJECTIVES
While the general purpose of the project was to put the ash issue into proper perspective, the
project has some specific objectives.
1.	Provide a compilation of existing knowledge concerning MSW incinerator residues;
2.	Define uniform protocols for the sampling and full characterization (including defining
chemical, physical, and leaching properties) of incinerator residues;
3.	Describe the fate and behaviour of contaminants during the incineration process including
documenting the effects of different incinerator designs, air pollution control systems,
incinerator operations and refuse feedstocks;
4.	Evaluate and develop recommendations with regard to current or proposed disposal, treatment
utilization and recovery practices;
5.	Provide regulators with recommended standard performance criteria for the residues under
different management scenarios;
6.	Identify areas for further research and development.
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APPROACH
The IAWG has met eleven times over the past three years to discuss selected topics. Each meeting
has been at a different venue to allow the group to meet with interested parties in different
countries. In addition, international seminars have been held on several occasions to bring together
regulators and researchers to discuss economically and environmentally sound ash management
practices. For example, the IAWG has held two major seminars on leaching protocols, one in
Europe and the other in North America.
Most of each meeting was devoted to review of specific topics as selected from the original outline.
Members of the group prepared for the meetings by gathering together information on the selected
subject(s) and provided this material to the group at the meetings. The discussions that ensued lead
to the development of draft chapter outlines. Information supplied by the group has been, or is
currently being compiled into draft chapters following the outline. Several of the chapters are
currently undergoing review by the sponsoring agencies. The remaining chapters are in various
stages of preparation. Hie IAWG has also routinely consulted with other researchers in the field
to ensure that the broadest range of perspectives have been considered for incorporation into the
document.
It appears that the final document will be extensive, containing detailed background discussions on
many technical issues such as thermo-chemical behaviour of trace metals, leaching mechanisms and
engineering tests. The IAWG is considering summarizing the report and publishing a hard cover
version for release to the general public. It is anticipated that the release of the summary document
will coincide with two major conferences on MSW Incinerator Residues to be held by the IAWG,
one in North America and the other in Europe in the Spring of 1994.
In addition to the original mandate of the Group, the IAWG has been designated as a full Activity
under the International Energy Agency's Bioenergy Agreement - Conversion of MSW to Energy Task
XI. Consequently, the IAWG now has a mandate to meet through 1994 to consider revisions to the
final report based on the review of any new evidence from current research topics.
Benefits
The IAWG is committed to providing the sponsors with the information necessary to make sound
decisions regarding MSW incinerator residue management.
1.	Outline criteria for data gathering to assist other researchers with project development and
generation of quality comparable data;
2.	Develop a framework on which to build characterization protocols for assessing incinerator
residues;
3.	Provide a bench-mark for other researchers by compiling the data and identifying areas
requiring further research;
4.	Enable regulators, the public and industry to make decisions on the environmental acceptability
of alternative management options for the residues;
5. Develop a framework for international collaboration on managing other wastes.
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Funding
In order to ensure objectivity, the 1AWG sought out funding based on equal contributions from a
large number of government agencies, private organizations and companies. The IAWG gratefully
acknowledges the support provided by:
Malor Sponsors
Asea Brown Boveri Ltd
California Integrated Waste Management Board
Danish Ministry of Energy
Energy, Mines & Resources Canada
Environment Canada
European Economic Community
Kernforschungszentrum Karlsruhe
International Energy Agency
Minor Sponsors
American Society of Mechanical Engineers
Greater Vancouver Regional District
IRR/IWSA
International Lead Zinc Research Organization
LAB France
NOVEM/RIVM Netherlands
Swedish National Board for Industrial & Technical
Development
United Kingdom Department of the Environment
United States Environmental Protection Agency
Wheelabrator Environmental Systems Inc.
Northeast Waste Management Officials Association
New Jersey - Solid Waste Administration
Waste Processing Association Netherlands
PROJECT UPDATE
It was at the second meeting that it became evident that the original desire of the group to amass
a global data base of ash information was not going to be possible. Far too much data exists to
organize it in the context of this project and more importantly, most of these data were created using
methods that are not fully described in the references. Chapters on ash characteristics are taking
shape at this time and the data available has been incorporated to illustrate pertinent points. By
using this case study approach much of the relevant material can be included in the document.
Subjects addressed in the report presently include:
o the nature of MSW in the various countries;
o the MSW incineration practices in the various countries: variations in combustion, air pollution
control and material handling technologies; residue management practices; and, the regulations
governing the operation of plants.
o the sampling and analysis of residue materials;
o the characteristics of various residue streams based upon the results of sampling and analysis
work conducted along the line of the recommended procedures;
o the fate of elements in the combustion process and in the environment as a function of
combustion and APC technologies and the management practices utilized;
o the leaching of residues, basic chemistry issues, leaching tests and ash leaching data;
o the treatment and modification of residues including a generic outline of possible alternatives
and detailed discussions of solidification/stabilization; separation; and, thermal treatment.
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o both the chemical and physical properties of products made from treated incinerator residues;
o the disposal or utilization of residues, including a review of the alternatives available and how
they arc influenced by fate and transport systems; the short and long term impacts of these
alternatives;
o containment, partial containment, controlled contaminant release, monofilling and co-disposal
alternatives and various utilization options;
o the public perception of these issues; and,
o the recommendations that arise from the study.
This Conference precedes the 12th meeting of the IAWG since February 1990. The list of chapters
for the final publication now stands at 29. Of this total, over half the chapters have been submitted
to the sponsors for review and comment. The IAWG has targeted the end of August 1993 for
completion of the final draft report.
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TECHNICAL REPORT DATA
(Please read /nstrucnons on the reverse before com


1. REPORT NO.
EPA/600/A-94/217
2.



4. TITLE AND SUBTITLE
The International Ash Working Group: A State-of-
5. REPORT DATE

Knowledge Treatise on MSW Incinerator Residues
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
S.W. Sawell1, A.J. Chandler2, T.T. Eighmy^, J. Hartlen4
0. Hjelmar^, D. Kosson®, H.A. van der Sloot^,J. Vehlow®
8. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORGANIZATION NAME AND ADDRESS ICOIttpaSS EttVl InC. ,
2a.J. Chandler & Assoc. Ltd, %niv of New Hampshire,
^Swedish Geotechnical Inst.,5Danish Water Quality Inst.,
^Rutgers Univ, ^Netherlands Energy Research Foundation,
%ernforschungszentrum
10. PROGRAM ELEMENT NO.
11. CONTRACT/GRANT NO.
12. SPONSORING AGENCY NAME AND ADDRESS
Risk Reduction Engineering Laboratory—Cinti, OH
13. TYPE OF REPORT ANO PERIOD COVERED
Published Paper
Office of Research and Development
U.S. Environmental Protection Agency
Cincinnati, OH 45268

14. SPONSORING AGENCY CODE
EPA/600/14
is.supplementary notes Project Officer = canton c. wiles (513)569-7795
1993 International MWC Conference, Research Triangle Park, NC, May 1993, p: 1-5
16. ABSTRACT
This paper summarizes objectives and progress of the international ash working
group (IAWG) to develop a treatise on municipal solid waste (MSW) incinerator
residues. The purpose of the treatise is to provide a state-of-knowledge on the
characteristics, protocols for sampling and characterizing, fate and behavior of
contaminants, treatment and utilization alternatives and other factors concerned with
MSW incinerator residues. The IAWG is compressed of internationally recognized
experts from Canada, Sweden, Denmark, Germany, the Netherlands, and the United States.
17.
KEY WORDS AND DOCUMENT ANALYSIS


a. DESCRIPTORS
b.IDENTIFIERS/OPEN ENDED TERMS
c. COSATi Field/Croup
incinerator
ash working group,
treatise

18. DISTRIBUTION STATEMENT

19. SECURITY CLASS (This Report)
Unclassified
21. NO. OF PAGES
6
Release to public

20. SECURITY CLASS (This page1
Unclassified
22. PRICE
EPA Form 2220-1 (Rat. 4-71) previous edition is obiolete

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