United States
Environmental Protection
Agency
Solid Waste and
Emergency Response
(OS-305)
EPA/530-SW-90-037
Spring 1990
vvEPA
MUNICIPAL WASTE COMBUSTION
ASH INFORMATION UPDATE
This Information Update provides a
status report on projects involving
the use of municipal waste combus-
tion (MWC) ash and other MWC
residues. This first edition focuses
on research, development, and
demonstration projects currently
under way in the United States.
Subsequent editions will report on
research activities, as well as
commercial-scale projects, taking
place in other countries and in the
United States.
The Environmental Protection
Agency (EPA) would appreciate
comments from readers on the
usefulness of the information in this
research update, as well as sugges-
tions on additional types of informa-
tion that would be of interest.
Address comments to: Municipal
Solid Waste Program, MWC Ash
Update, OS-301, U.S. Environmental
Protection Agency, 401 M Street, SW,
Washington, D.C., 20460.
EPA Projects
Evaluation of Solidification/Stabili-
zation and Other Technologies for
Managing MWC Ash; Office of
Research and Development, Waste
Minimization, Destruction and Dis-
posal Research Division
This project is the first phase of the
EPA Office of Research and
Development's program to provide
credible data that municipalities can
use to plan and implement strategies
for managing ash, The objective of
this project is to investigate the effec-
tiveness of solidification/stabiliza-
tion and other technologies in
eliminating or reducing the release of
toxic constituents from MWC ash
and its leachate. The program is
designed to evaluate treatment
technologies, rather than to deter-
mine how ash characteristics are
affected by MWC designs, operating
conditions, and waste input. There-
fore, all investigations will be con-
ducted using ash from the same
facility.
In April 1989, EPA's Office of Re-
search and Development issued a
Request for Participation in the pro-
gram. EPA agreed to pay for collec-
tion and processing of the ash before
providing it to treatment vendors,
and for physically and chemically
testing untreated and treated ash
residues. Vendors were expected to
pay for the transportation of their
process technology, costs for person-
nel conducting on-site activities, and
for the demonstration of the treat-
ment technique.
Vendors were selected, and the
program was initiated in the fall of
1989. Preliminary data from three
process investigations are expected
to be available in the fall of 1990. A
Technical Advisory Panel, consisting
of members from the private sector,
environmental advocacy groups, in-
cineration vendors, academia, state
regulatory agencies, federal and
foreign regulatory agencies, and
trade associations, assisted EPA in
developing the program, evaluating
proposals, and selecting vendors.
The panel will continue to help EPA
evaluate the performance of treat-
ment technologies as the program
proceeds.
For further information, contact
Carlton C. Wiles, Chief, Stabilization
Section, MSWRMB, WMDDRD, U.S.
Environmental Protection Agency,
26 W. M.L. King Drive, Cincinnati,
OH 45219; (513) 569-7795.
Projects Outside EPA
Ash Utilization for Artificial Reef
Construction in Long Island Sound;
Marine Sciences Research Center,
State University of New York at
Stony Brook
In May 1985, the Marine Sciences
Research Center initiated a research
program to examine the feasibility of
using stabilized incineration residues
(SIR) to build artificial reefs in the
ocean. These studies showed that
incineration residues could be
combined with cement to form a
solid block possessing the physical
properties necessary for ocean dis-
posal.
Following these studies, in Decem-
ber 1986, the Besser Company
research facilities at the Alpena
Community College in Alpena,
Michigan, began making blocks with
SIR using conventional block-
making machines. The block mix
consisted of 63.8 percent combined
fly and bottom ash, 21.2 percent
crushed ash, and 15 percent Portland
Type II cement. Water was added to
adjust the moisture content of the
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mix to 10.2 percent. The well-mixed
materials were then fed into the
block-making machine to mold 8-by-
8-by-16 inch blocks with a hollow
core. - '
In April 1987, SIR blocks and stan-
dard cement blocks were submerged
at a depth of approximately 26 feet in
Conscience Bay in Long Island
Sound, N.Y. In the bay, tidal currents
can exceed 6 mph and sediments are
composed mainly of poorly sorted
gravel and coarse sand. The blocks
were arranged in two separate reefs
about five feet apartone composed
of SIR blocks, and the other with
concrete blocks. Each reef was de-
signed to maximize the surface area
exposed to sea water and to provide
numerous crevices to facilitate
biological colonization.
After their placement in Conscience
Bay, the blocks were periodically
retrieved for unconfined compressive
strength testing. When blocks were
last retrieved after 380 days of
exposure to seawater, the strength of
SIR blocks remained constant at 1,103
pounds per square inch (psi), while
the strength of the concrete blocks
decreased from 1,087 psi to 779 psi.
Metals of environmental concern, in-
cluding lead and cadmium, showed
no signs of leaching.
Diver and photographic surveys were
conducted from April 1987 to May
1988 to document the organisms
colonizing the two reef structures.
Both structures were colonized rap-
idly, with hydroids attached to all
sides within six weeks of placement.
As the summer progressed, bryozoan
colonies succeeded the hydroids as
the dominant species growing on the
reef surfaces. In addition, the struc-
tures attracted several fish species.
Continued monitoring of the reef site
is planned and will provide data on
the long-term effects of SIR on the
marine environment.
Additional Research at SUNY/
Stony Brook
Two new research projects are
underway at the State University in
Stony Brook. One is examining the
possibility of using ash-containing
concrete blocks^in the construction of
retention walls, or shore protection
devices. Researchers are studying
ways to upgrade the reef block mix
because retention walls require
much greater structural integrity. A
boathouse with ash-containing
blocks is also being constructed, with
both the inner and the outer walls
containing ash. In addition, studies
are under way to test the possibility
of using ash in construction materi-
als.
For further information, contact Dr.
Frank Roethel, Marine Sciences
Research Center, Waste Management
Institute, State University of New
York, Stony Brook, NY, 11794; (516)
632-8732, or consult the Waste Man-.
agement Research Report, "Stabilized
Incinerator Ash Tested in Construc-
tion of Artificial Reef," by Dr. F.J.
Roethel and V.T. Breslin.
Ash Utilization for Artificial Reef
Construction in the Gulf of Mexico;
HDR Engineering, Inc. and Honda
Institute of Technology
In May 1989, Pinellas County,
Florida, sponsored a project to
evaluate the potential for using
stabilized MWC ash in the construc-
tion of an open ocean reef in the Gulf
of Mexico. HDR Engineering, Inc. is
serving as a contractor to the county,
along with Florida Institute of Tech-
nology as a subcontractor.
The process of stabilization involves
mixing granular solid waste with
chemical additives and curing the
mixture at a constant temperature
for a specific period of time. The
proposed research program consists
of:
permitting and site selection;
characterizing the ash;
developing the mix design;
, conducting engineering and
chemical evaluations of the
stabilized ash used for building
the artificial reef;
designing and fabricating the
artificial reef;
placing the reef in the ocean by
the end of 1990 to initiate the field
demonstration program; and
evaluating the economic feasibil-
ity of using stabilized MWC ash
to build artificial reefs.
*
Three MWC ash types will be pro-
vided by Pinellas County for charac-
terization and use in constructing
the reefs:
100% bottom ash (grate ash);
100% fly ash; and
fly ash combined with scrubber
sludge.
To evaluate the effectiveness of
stabilization in reducing leachate
from MWC ash exposed to seawater,
a series of leaching experiments will
be conducted on the loose ash under
varying conditions of ash/sea water
ratios, pH, and proportions of fly
ash and bottom ash that correlate
with selected mix designs. The mix
for the artificial reefs will be de-
signed so that it can be cast into
shapes, and will contain about 15
percent cement.
The proposed reef system will be
comprised of duplicate reefs for each
accepted mix. In addition, two reefs
will be constructed of known
material (concrete). For relatively
uncomplicated shapes, artificial reef
units will be loaded onto a pocket
barge and the units will be dropped
continuously until a reef of
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appropriate profile and size is
Bated. Scuba divers will check on
progress of the reef profile.
Monitoring will be conducted to
decide if the MWC ash is an environ-
mentally acceptable material for
artificial reef construction. The
monitoring program will consist of
studies to evaluate the specific
engineering aspects of the reef
system; chemical and mineralogical
studies to determine rate of release of
metals, rate of uptake of magnesium,
formation of new minerals, variation
of trace elements and organic compo-
sition of the blocks; biological studies
to investigate the colonization and
diversity of organisms on the blocks
and around the reef site; and bioaccu-
mulation studies focusing on the
fouling communities collected from
the reef site.
For further information contact
Sheree Stewart, HDR Engineering,
Inc., Suite 225,5100 W. Kennedy
Boulevard, Tampa, FL 33609-1806;
fg!3) 287-1960.
Ash Utilization in Bituminous
Concrete; New York Department of
Environmental Conservation
The purpose of this project is to
determine the suitability of MWC
residue as an aggregate in bitumi-
nous concrete. The study is a joint
effort of the Long Island Regional
Planning Board, the New York State
Energy Research and Development
Authority, the Port Authority of New
York and New Jersey, and the New
Jersey Department of Transportation.
The New York State Department of
Environmental Conservation is in-
volved in an advisory capacity.
The research is intended to evaluate
the engineering properties of incin-
erator residues (bottom ash and
combined ash) and the environ-
mental concerns associated with
King ash as a substitute aggregate
material. This will be accomplished
by a series of laboratory tests on ash,
followed by construction of a test
pavement section which will be
monitored for approximately three
years.
In the initial phases of the study,
bottom and combined ash will be
sampled and tested for uniformity
and suitability as an aggregate, and
for heavy metals, organics, and
toxitity.
The study will examine potential
problems arising from stockpiling
ash for the long periods (3-6 months)
that would occur if ash was used as
an aggregate. Potential problems to
be monitored include the generation
of stockpile dust, runoff, and physi-
cal changes in the material. In
addition, samples of the stockpile
material will be tested in the labora-
tory where personnel and facilities
will be monitored for fugitive dust
exposure.
The study will evaluate the produc-
tion, and placement on a roadway, of
bituminous concrete that includes
the incinerator ash as a portion of the
aggregate. This will be accompanied
by monitoring for air quality, waste-
water problems, and worker safety
parameters'.
The final portion of the study will be
devoted to monitoring the perform-
ance of the roadway sections under
traffic conditions to assess the
engineering properties of the bitumi-
nous mixture, and testing any
leachate and runoff for heavy metals,
organics, and toxicity. The findings
of the research will be documented
in a final report.
For further information contact
Norman Nosenchuck, Division of
Solid Waste, New York State Depart-
ment of Environmental Conserva-
tion, 50 Wolf Road, Albany, NY,
12233; (518) 457-6603
Vitrification of Residue from
Municipal Waste Combustion
Facilities; American Society of Me-
chanical Engineers, U.S. Bureau of
Mines
This study will examine whether
residue from the burning of munici-
pal waste can be fused into a glassy
material (vitrified) usable in con-
struction.
Vitrification immobilizes toxic mate-
rials in the residue. By testing
samples of residue from seven to ten
municipal waste combustion facili-
ties, the researchers hope:
to confirm that the glass-like
product is environmentally
benign, denser than the original.
residue, and takes less energy to
produce than is recovered from
burning municipal waste;
to determine the optimal condi-
tions and operating constraints for
running an electric arc furnace to
vitrify combustion residue, either
continuously or during off-peak
power periods;
to identify beneficial uses for
vitrified residue, potential mar-
kets and potential limitations on
the product's use; and
to identify the amount and nature .
of any residual material, emission
or effluent.
For further information contact
David Lewin, ASME Public Informa-
tion, Suite 216,1825 K Street, NW,
Washington, D.C. 20006; (202) 785-
3756.
Utilization of Ash Products from
Combustion of Shredded Solid
Waste; Energy Answers Corporation
and SUNY College of Environmental
Science and Forestry
The purpose of this research is to
characterize aggregate from combus-
tion of refuse-derived fuel (RDF) and
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to assess the feasibility of, and
environmental impacts from, using
bottom ash from an RDF unit as an
aggregate substitute. This project is
a joint venture of Energy Answers
Corporation (EAC), the SUNY
College of Environmental Science
and Forestry, Smith and Mahoney,
P.C., and Rensselaer Polytechnic
Institute.
Specific project tasks include: (1) the
production, sampling, and testing of
the ash aggregate over the course of
a year to assess the variability of
physical and chemical characteris-
tics; (2) simulation of aggregate
stockpiling and storage to determine
potential environmental impacts; (3)
the production of concrete products
made from ash aggregate for per-
formance and environmental testing;
and (4) an assessment of the suitabil-
ity of ash aggregate in proposed uses
based on environmental, handling,
health, and safety criteria.
Bottom ash was obtained from an
RDF facility in Albany and sampled
on a daily basis throughout the year.
Processing of the ash involved
removal of metals and material
greater than one half inch (the
remaining material is referred to as
"ash aggregate" or "boiler aggre-
gate"). The Toxicity Characteristic
Leaching Procedure and the Extrac-
tion Procedure toxicity tests were
regularly performed on the ash
aggregate to determine its regulatory
classification. The following physical
characteristics of the ash aggregate
were monitored:
grain size distribution;
moisture content;
density and specific gravity;
cation exchange capacity;
percentage of constituent
materials;
comparability; and
percentage of metals.
Tests were also performed twice a
month to determine the variation in
the physical and structural character-
istics of the ash as a function of
seasonal variation in the solid waste
input stream.
Initial results support the use of ash
aggregate as an aggregate substitute
for many applications. Data from the
open-pile storage simulation suggest
that ash aggregate stockpiled outside
and exposed to acid rain (pH 4)
produces a leachate with negligible
levels of heavy metals. Ash-
containing concrete products sub-
jected to acid rain also produce a
leachate with negligible levels of
heavy metals and maintain compres-
sive strengths comparable to those of
conventional concrete products.
Recently the New York Department
of Environmental Conservation ap-
proved the ash aggregate for use as a
road base asphalt aggregate. -i
For further information, contact
Jocelyn Mullen, Energy Answers Cor-
poration, 79 N. Pearl Street, Albany,
NY 12207; (518) 434-1227, or refer to
EAC's Paper #88-24.14 "Utilization of
Ash Products from Combustion of
Shredded Solid Waste," by Patrick
Mahoney and Jocelyn Mullen.
Trace Metal Recovery from Munici-
pal Solid Waste Incinerator Ash;
Rutgers, The State University of New
Jersey, Department of Chemical and
Biochemical Engineering
One approach for the treatment of
incinerator residuals is component
separation and recovery, which relies
on removal and recycling of poten-
tially hazardous constituents. This
approach returns bulk and trace met-
als to the marketplace and allows
reuse of the inert constituents as an
aggregate.
Since 1984 the New Jersey Hazardous
Substance Management Research
Center has funded a research, devel-
opment, and evaluation effort for
separation and recovery of trace
hazardous constituents from incin-
erator residuals. The project's
specific objectives are:
to chemically and physically
characterize untreated and treated
residuals and process streams;
to define process requirements for
separation and recovery of regu-
lated metals (e.g. lead, cadmium)
and soluble salts (e.g., chlorides,
sodium, and calcium);
to identify potential markets and
market requirements for use of
treated residuals and process
streams; and
to evaluate process economics for
various recovery scenarios*
This effort has identified the physical
and chemical characteristics of
bottom and fly ashes from several,
MWC facilities in the United Stat4
and Canada and has defined the
chemistry of a viable separation and
recovery process for heavy metals.
The process employs aqueous
extraction at mildly acidic conditions
in the presence of chlorides to
achieve high separation efficiencies,
followed by selective electroplating
of heavy metals. Efforts to date have
focused on lead and cadmium
recovery. Typical removal efficien-
cies from fly ashes have been 70-80
percent for lead and greater than 95
percent for cadmium. A laboratory
process facility operating at a rate of
one kg/hr of ash has been under
development since 1988. An out-
growth of this laboratory facility will
be design criteria and economic
evaluation for full-scale demonstra-
tion of the process (10-20 tons/day).
Extraction studies using ash from
several resource recovery facilities
provided insight to the leaching
characteristics of the ashes and the
effects of the composition of the
extract solution. Various salt
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solutions were investigated for their
capability to extract heavy metals.
The effect of the cations in the salt
solutions was observed at neutral
and acidic equilibrium conditions.
An ash/extract equilibrium pH of 3.0
was found to be the most efficient
level of acidity to remove higher
amounts of lead. The presence of
chloride salts in solution also signifi-
cantly increased the ability of the
extract to recover lead from the ash
residues.
The extractable levels of cadmium
for all of the residual ashes stabilized
rapidly, and the removal mechanism
did not exhibit a pH dependency.
Trace levels of cadmium and chro-
mium were readily extracted from all
the ashes investigated.
For further information, contact
David Kosson, Rutgers, The State
University of New Jersey, Depart-
ment of Chemical and Biochemical
Engineering, P.O. Box 909, Piscata-
way, NJ 08855; (201) 932-4346, or
consult Trace Metal Recovery from Mu-
nicipal Solid Waste Incinerator Ash, by
Dr. David Kosson, LA. Legiec and C.
Hayes.
Use of Incinerator Ash in Pave-
ments; New Jersey Department of
Transportation
Through the Interagency Engineer-
ing Committee, the New Jersey
Department of Transportation is in-
vestigating the possible uses of incin-
erator ash in roadway pavements.
The Interagency Committee is com-
posed of engineering managers from
the New Jersey Department of Trans-
portation, the Port Authority of New
York and New Jersey, the New
Jersey Turnpike Authority, the New
Jersey Highway Authority, the New
Jersey Department of Treasury, and
the Delaware River Port Authority,
who joined forces to address com-
mon engineering problems. The
Committee has elected to combine
their efforts with a research project
already under way in the State of
New York.
This project involves the full-scale
production of asphalt paving materi-
als partially composed of incinerator
ash, and use of the asphalt in the
construction of pavements. The
Committee has proposed using an
asphalt plant in New Jersey to
produce the paving material and to
place the materials on one of New
Jersey's highways. The field trial
will include paving materials
produced from both bottom ash and
combined ash; however, paving in-
vestigation work will emphasize the
use of bottom ash. The N.J. Depart-
ment of Transportation hopes to
install test pavements in the summer
of 1990.
For further information, contact
Kenneth Afferton, N.J. Department
of Transportation, 1035 Parkway
Avenue, Trenton, NJ, 08625; (609)
530-2529.
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