United States
Environmental Protection
Agency
Hazardous Waste Engineering
Research Laboratory
Cincinnati OH 45268
Research and Development
EPA-600/S2-84-170 Jan. 1985
x°/EPA Project Summary
Methods/Materials Matrix for
Ultimate Disposal Techniques
for Spilled Hazardous Materials
B.W. Mercer, G.W. Dawson, J.A. McNeese, and E.G. Baker
This study reviews and evaluates
various conventional and novel methods
for the ultimate disposal of spilled or
released hazardous materials. The
object was to use the data on actual
spilled material characteristics as the
basis for selecting the most appropriate
ultimate disposal methods for residues
from spill cleanups. The conventional
methods reviewed are: biotreatment,
chemical treatment (neutralization,
oxidation, and reduction), incineration,
pyrolysis, landfilling, and fixation.
Novel processes considered are: wet air
oxidation, improved thermal degradation,
microwave and plasma destruction,
selective biodegradation, high tem-
perature physical and chemical fixation,
and oxidation with aqueous bromine.
The report discusses the problems
and requirements of applying each of
these techniques to large and small
hazardous substance spills and releases,
particularly in situations where the
spilled or recovered waste material is
mixed with debris and various other
chemicals.
An attempt was made to use chemical
and physical properties to specify
preferred disposal methods for a wide
range of toxic and hazardous substances
and wastes. The original matrix format
proved to be too complex and required
too many subclassifications to be
useful. In its place, what was developed
is a generalized matrix that used
conventional classifications of the
technology available in the mid-1970's.
The matrix generated can assist on-site
coordinators in making assessments of
the preferred disposal routes for hazard-
ous wastes and spill residuals. The more
generalized matrix is subdivided accord-
ing to the physical and chemical
properties of the hazardous materials
and the nature of the other wastes or
debris present in the residue.
A second version of the matrix was
also developed on the assumption that
secured landfills would become unaccept-
able in the future and that certain novel
techniques now under development
could play a significant role at that
time. The need for new disposal technolo-
gy is addressed.
This Project Summary was developed
by EPA's Hazardous Waste Engineering
Research Laboratory, Cincinnati, OH,
to announce key findings of the re-
search project that is fully documented
in a separate report of the same title (see
Project Report ordering information at
back).
Introduction
This study was conducted during the
late 1970's and contains dated information
pertaining to U.S. Environmental Protection
Agency regulations and policies. Conse-
quently, the reader is reminded to retain
the same perspective that would be
appropriate in reading any document
several years after its initial preparation.
Particular care should be exercised when
considering the cost data and references
to "current and anticipated" regulations
and Agency policies, many of which have
now become much more demanding. It
was decided to publish this report, even
though portions are out of date, based on
the potential benefits that could be
derived from the technical content of the
study.
Regulation and control of the transport
and disposal of hazardous substances
(and particularly hazardous wastes) have
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become a primary environmental issue.
Though restrictions are intended to apply
mainly to hazardous industrial wastes,
they also apply to hazardous wastes and
residues encountered at spill sites.
Cleanup procedures at spill incidents
usually address the onsite collection,
containment, and deactivation of specific
wastes in a manner that minimizes
damage to the immediate environment
(air, land, water) and reduces the hazard
to people, other living entities (animals,
flora), and structures. Little attention has
been devoted to the ultimate (final)
disposal of the accumulated wastes after
spilled or released hazardous substances
have been collected, chemically modified
to prevent damage to the local environment,
and/or physically mixed with debris,
sorbents, water, etc. Procedures that are
appropriate for the destruction or disposal
of pure or highly concentrated hazardous
wastes are frequently not practical or
even technically appropriate once a
material has been retrieved from the
environment, often under adverse condi-
tions. Nevertheless, before a response
activity can be considered complete, final
destruction or disposal of the residual
materials should be planned and imple-
mented to ensure minimal long-term
environmental impact. Such final action
may be unnecessary in only a few cases,
e.g., highly volatile spilled material, that
has already entered the air column,
releases that have been dissolved in a
large volume river, hazardous substances
that have been absorbed by soil in a
manner that permanently immobilizes
components of concern (heavy metals).
In the absence of specific guidance for
cleanup personnel, best engineering
judgement has been the only basis for
selecting a final disposal process for spill
residuals. The purpose of this study was
to develop a system of preferred or ranked
disposal, destruction, and treatment
options that- (1) would be based on the
chemical and physical properties of the
residues and (2) could be applied to a
variety of spilled materials under a wide
range of conditions. It soon became
apparent that a complex matrix system
that incorporated a detailed compilation
of all the different factors and combinations
could not be generated in a practical,
useful form. A more generalized matrix
was therefore developed for qualitative
guidance for field personnel. The matrix
does include factors such as reactivity,
solubility, leachability, availability of
sites, etc.
The generalized matrix was subsequent-
ly modified on the assumption that
secure landfills (as used in the 1970's)
would cease to be viable alternatives in
the future. In addition, the modified
matrix anticipated that treatment systems
now under development (such as those
discussed in the body of the report) would
become commercially available and
would expand the options open to the on-
site coordinator.
The information presented here and in
the full report reflects the status of the
soil treatment and waste disposal indus-
try as it existed in the late 1970's. In the
intervening years, significant changes
have occurred in technology, promulgation
of regulations, definition of social de-
mands and impact of economics.
Treatment Options
For a variety of reasons, not every spill
receives or requires cleanup. In addition,
not every spill cleanup generates residues
that are hazardous, even by current
standards. For example, of a random
sampling of 78 hazardous material spills
occurring from December 1975 to May
1977, 28 (36%) received "no cleanup".
The cleanup techniques for the others
(64%) were as follows:
Item
No. of Incidents
Water wash 19 (24%)
Chemical treatment 9 (11 %)
Recovery 6 (8%)
Landfill 2 (3%)
Biotreatment 1 (1%)
Nothing reported
(excludes "no cleanup") 13 (17%)
Of course, these data are not necessarily
representative of all spill incidents.
To develop a basis for a matrix of
treatment options for various wastes, the
authors reviewed a wide range of
technologies for the ultimate disposal of
hazardous wastes and made qualitative
judgements about the applicability of
these technologies to spill residues. Key
comments considered during development
of the treatment matrix are noted in the
following paragraphs.
Biological Processes
Without further treatment, even the
upper level of removal achievable with
biological treatment processes (about
90%) may not be adequate for hazardous
or toxic substance releases. Approaches
such as trickling filters, activated sludge
systems, etc. are used for hazardous
wastes (intentionally and otherwise) but
land application is probably the method
most cost-effective and most readily
applicable to spill residuals. More than
half of the hazardous materials defined by
various Federal agencies and tabulated in
the appendix of the full report are
expected to be susceptible to biodegrada-
tion. Note that other constituents of a spill
residue may also play a role in the
success of a particular process.
Incineration
The basic process technology for
incineration is well-developed and well-
suited to the ultimate disposal of organic
hazardous wastes although the nature of
the ash remaining from specific wastes
may need special attention. Various
systems can handle viscous liquids, tars,
solids, etc. These systems include
multiple hearths, rotary kilns, fluidized
beds, catalytic combustors, and olhers.
Cost and accessibility of the appropriate
equipment are the key factors in selecting
an incinerator for disposal of the residuals
from a hazardous spill (or release)
cleanup. Certain wastes such as PCB's,
require extreme conditions to achieve the
required destruction. The incineration of
chlorinated wastes at sea is a special
case receiving increasing attention for its
ability to avoid the air pollution problems
inherent in land-based incineration.
More than half of the hazardous materials
listed in the report appendix are appropriate
candidates for incineration (in general,
the exceptions are the inorganic materials).
Neutralization
Neutralization with strong or weak
acids and bases is widely used in the
cleanup of hazardous chemical spills.
This process can also contribute to the
insolubilization of other hazardous
components such as chromic tons (Cr-lll).
Precipitation
Precipitating agents are often used
during cleanup procedures to separate
inorganic hazardous species from other
spill components. Once precipitated as
oxides, carbonates, or sulfides, many
metals are sufficiently insoluble to be
disposed of as nonhazardous wastes.
Chemical Oxidation and
Reduction
Though a number of oxidants and
reductants are used in chemical process-
ing, only a few are suitable for field use.
These include sodium and calcium
hypochlorite, hydrogen peroxide, sodium
sulfite, ferrous sulfate, and sulfur dioxide.
Fixation \
Organic fixation agents such as tar,
asphalt, polyolefins, and epoxy resins can
be used to immobilize (encapsulate) ^
residuals, but many of the products are \
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sensitive to disintegration by the ultravio-
let component of sunlight, indigenous
microorganisms, weathering, etc. Inorgan-
ic silicates have been used, primarily, to
retard the movement of heavy metals in
landfilled sludges.
Sanitary Landfills
Without protection (use of liners or
collection of leachate) against the
migration of hazardous or toxic waste
constituents, sanitary landfills are unsuit-
able for hazardous wastes. But, when
spilled material has been detoxified or
otherwise deactivated, ultimate disposal
in a sanitary landfill may be acceptable if
it meets Federal, state, and local regulations.
Secured Landfill
Secured landfills equipped with imper-
vious liners and leachate collection
systems may meet future requirements
for the storage of hazardous wastes.
Separate cells for reactive wastes can
prevent chemical interactions that could
solubilize otherwise immobile materials.
Besides technical requirements, a secured
landfill must also meet strict permitting
and reporting requirements. The long-
term integrity of such sites is an ever-
present question.
Deep-Well Injection
The injection of liquid wastes into
strata isolated from potentially usable
groundwater is an attractive option for
wastes that are difficult to treat by other
routes. The use of this method will
continue to be severely restricted by the
need to assure that a well is truly isolated
from groundwater.
Ocean Disposal
Though dumping into the ocean has
been used for disposal of various wastes
and while the ocean does have a
buffering capacity unmatched by any
land-based system and possesses signifi-
cant biodegrative capacity, ocean disposal
is now encountering heavy public resistance.
Matrix Development
Even after a cleanup, a hazardous
material spill may leave a residue that
must still be regarded and disposed of as
a hazardous material. In other cases,
dilution with soil or water will change the
character of the spilled material so that it
may be disposed of as a nonhazardous
material.
The character of a spilled material often
derives from its condition after capture,
collection, and clean-up. The waste may
be essentially unchanged and mixed with
only small amounts of extraneous material;
or it may be diluted with water, mixed
with other combustible materials or
mixed with other noncombustible materials
such as soil, debris, and organic detritus.
The actual nature of the residue often
dictates the choice of disposal method.
Recovery should be the first option
considered, particularly where the waste
is unchanged and only slightly contamin-
ated with other material. Mixtures with
water are generally approached as
waterborne wastes and are treated with
neutralization, precipitation, bio-oxidation,
and adsorption. When some components
of the mixture are combustible, incineration
may be the preferred route. But, when the
other components are noncombustible,
the mixture requires careful selection of
separation and treatment processes to
assure that all the components are
disposed of safely.
As noted, it was impractical to develop
a matrix for specific compounds or even
for families of compounds on the basis of
their chemical or physical properties.
Many other factors, related to physical
state, chemical composition, location,
etc., affect the final choice of a treatment
process for spill residues.
The alternative approach (Table 1)
divides hazardous waste into organic and
inorganic categories. Organics are further
divided into reactive, unreactive, and
highly toxic/persistent classes. Inorgan-
ics are categorized as reactive and highly
toxic persistent. In these designations,
reactivity refers to the ease of biochemical
or chemical deactivation. Nonreactive
organics are those that are not responsive
to such chemical or biochemical process-
es and must, consequently, be inciner-
ated, disposed of in a secured landfill, or
otherwise detoxified or destroyed. The
toxic/persistent category is defined to
include compounds that are not degraded
in the environment in less than a year and
for which water solubility is greater than
1 mg/L (pesticides are examples).
When options are selected for deactivat-
ing spill residues, chemical or biochemical
degradation and incineration, even with
its high cost, are preferred to disposal in
secured landfills. Deep-well injection and
ocean disposal are not included in the
matrix because of anticipated restrictions
on their use.
Table 1 presents the preferential
treatment options for spill residues when
other materials of different character are
present. For residues that are primarily
organic, the preferred method is biochem-
ical degradation or, if necessary, chemical
treatment or pretreatment. Incineration
is preferred when the waste is non-
reactive and when any extraneous
material is combustible and manageable
in available equipment.
Secured landfill disposal is the preferred
route where the spill residue is highly
toxic or persistent and contains noncom-
bustibles.
In the case of inorganic wastes or
residues, fixation followed by placement
in a secure landfill replaces incineration
Table 1. Matrix For Conventional Disposal Methods
Type of Residue
Mixture with
Other Materials
Mixture with
minor amounts of
extraneous matter
Mixture with
substantial
amount of water
Mixtures with
combustible
solids
Hazardous Organic Waste
Reactive
B
O
S
A-B
A-0
A-S
B
O
Unreactive
0
S
A-O
A-S
O
S
Highly Toxic/
Persistent*
0
S
A-O
A-S
O
S
Hazardous
Inorganic Waste
Highly Toxic/
Reactive Persistent*
B F-S
B A- F-S
B F-S
Mixtures with B
small non- S
combustible solids
F-S
* = Toxicity characteristics given in full report
B = Treatment (chemical or biochemical)
O = Incineration
S = Secured landfill
F = Fixation
A = Concentrate and remove from water
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for those materials that cannot be
removed from the environment by chemical
treatment.
A modified matrix (Table 2) was also
developed for future use and is based on
two assumptions: (1) a secure landfill will
ultimately be unacceptable and (2)
certain novel technologies now under
development will become commercial
and will expand the range of deactivation
options available.
The following novel techniques are
cited in the full report as under development
at the time of the study:
1. Thermal destruction of polychlori-
nated biphenyls in cement kilns
2. Dehalogenation of chlorinated
hazardous wastes with elemental
sodium
3. Chemical oxidation of combustible
organic waste and waste mixtures
with aqueous bromine
4. Highly energy decomposition of
hazardous wastes and waste mix-
tures with microwave irradiation
5. Biochemical destruction of wastes
with specific microorganisms
6. Wet air oxidation of hazardous
wastes
Of these, all but microwave irradiation
and bromine/water oxidation are still
being actively considered.
Conclusions
Currently available technologies are
often satisfactory for the ultimate disposal
of the residues resulting from spills or
releases of hazardous materials of low
toxicity and persistence. But, at this time,
no basis exists to assure that the most
suitable method will be used in each spill
situation. The use of recognized (licensed)
hazardous waste management firms and
facilities will help to ensure that appropriate
methods are used.
Conventional technology is inadequate
for the ultimate disposal of highly toxic
and persistent materials, particularly
when the residues from a spill are mixed
with various extraneous materials.
Differing forms of thermal destruction,
including incineration, are well-suited to
the destruction of highly toxic organics,
but the distribution of suitably designed
installations across the country may be
inadequate to handle spill residuals.
Disposing of toxic heavy metals in spill
residues presents a special problem.
Since these metals cannot be destroyed,
various forms of fixation, as in glasses or
minerals, become attractive for long-term
immobilization.
Recommendations
Continued development of new disposal
methods is required to close gaps in the
Table 2.
Revised Matrix Using Novel Disposal Methods
Type of Residue
Mixture with
Other Materials
Hazardous Organic Waste
Hazardous
Inorganic Waste
Highly Toxic/ Highly Toxic/
Reactive Unreactive Persistent* Reactive Persistent*
Mixture with B O
minor amounts of O
extraneous matter
Mixture with A-B A-O
substantial A-O A-B
amount of water
Mixtures with L*-B O
combustible O L-B
solids
Mixtures with L*-B L-O
small non- L*-O L-B
combustible solids
A-O
A-B
O
L-O
L-B
F-S*
A-F-S*
F-F-S**
L-F-S**
+ = Toxicity characteristics given in full report
* = Optional
** = Not required if fixed product no longer meets hazardous waste criteria
B = Treatment (chemical or biochemical)
O = Incineration
F = Fixation
A - Concentrate and remove from water
L =Leach
S = Secured landfill
capability of current technology and to
overcome the lack of adequate disposal
facilities.
Specific efforts should be focused on
the total destruction of hazardous organic
materials and the long-term immobilization
of inorganic wastes, such as toxic
"heavy" metals both in their cationic and
anionic forms.
The use of landfill disposal for highly
toxic and persistent materials should be
phased out if the long-term integrity of
such sites cannot be assured.
Though various thermal destruction
systems are quite acceptable for the
destruction of hazardous organic wastes,
the distribution and availability of such
facilities must be increased.
Alternative destruction methods are
needed for: (1) localities where incineration
systems are not available or expected
soon, (2) low-volume wastes, and (3)
residues containing various types of
debris. Such alternatives include mobile
incinerators and chemical destruction
units for specific wastes (e.g., pesticides),
modest volumes of mixed wastes, and
residues from all but major spills and
releases.
Much more work is needed on the
fixation of inorganic wastes to assure
long-term immobilization of toxic ("heavy")
metals.
Spill cleanup personnel must be kept
familiar with evolving hazardous waste
regulations since these regulations apply
to the complex residues from spill
cleanups.
The full report was submitted in
fulfillment of Contract No. 68-03-2494 by
Battelle Pacific Northwest Laboratories
under the sponsorship of the U.S.
Environmental Protection Agency.
•&U. S. GOVERNMENT PRINTING OFFICE: 1985/559-111/10773
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B. W. Mercer, G, W. Dawson, J. A. McNeese, and E. G. Baker are with Battelle
Pacific Northwest Laboratories, Rich/and, WA 99352.
John £. Brugger is the EPA Project Officer (see below).
The complete report, entitled "Methods/Materials Matrix for Ultimate Disposal
Techniques for Spilled Hazardous Materials," (Order No. PB 85-11B 853; Cost:
$28.00, subject to change) will be available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Releases Control Branch
Hazardous Waste Engineering Research Laboratory—Cincinnati
U.S. Environmental Protection Agency
Edison, NJ 08837
United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
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