United States
Environmental Protection
Agency
Municipal Environmental Research EPA-600/2-79-056
Laboratory July 1979
Cincinnati OH 45268
Research and Development
vvEPA
Survey of
Solidification/
Stabilization
Technology for
Hazardous Industrial
Wastes
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RESEARCH REPORTING SERIES
Research reports of the Office of Research and Development, U.S. Environmental
Protection Agency, have been grouped into nine series. These nine broad cate-
gories were established to facilitate further development and application of en-
vironmental technology. Elimination of traditional grouping was consciously
planned to foster technology transfer and a maximum interface in related fields.
The nine series are:
1. Environmental Health Effects Research
2. Environmental Protection Technology
3. Ecological Research
4. Environmental Monitoring
5. Socioeconomic Environmental Studies
6. Scientific and Technical Assessment Reports (STAR)
7. Interagency Energy-Environment Research and Development
8. "Special" Reports
9. Miscellaneous Reports
This report has been assigned to the ENVIRONMENTAL PROTECTION TECH-
NOLOGY series. This series describes research performed to develop and dem-
onstrate instrumentation, equipment, and methodology to repair or prevent en-
vironmental degradation from point and non-point sources of pollution. This work
provides the new or improved technology required for the control and treatment
of pollution-sources to meet environmental quality standards.
This document is available to the public through the National Technical Informa-
tion Service, Springfield, Virginia 22161.
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EPA-600/2-79-056
July 1979
SURVEY OF SOLIDIFICATION/STABILIZATION TECHNOLOGY
FOR HAZARDOUS INDUSTRIAL WASTES
by
Environmental Laboratory
U.S. Army Engineer Waterways Experiment Station
Vicksburg, Mississippi 39180
Interagency Agreement No. EPA-IAG-D4-0569
Project Officer
Robert E. Landreth
Solid and Hazardous Waste Research Division
Municipal Environmental Research Laboratory
Cincinnati, Ohio 45268
MUNICIPAL ENVIRONMENTAL RESEARCH LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
CINCINNATI, OHIO 45268
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DISCLAIMER
This report has been reviewed by the Municipal Environmental Research
Laboratory, U. S. Environmental Protection Agency, and approved for publica-
tion. Approval does not signify that the contents necessarily reflect the
views and policies of the U. S. Environmental Protection Agency, nor does
mention of trade names or commercial products constitute endorsement or
recommendation for use.
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ii
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FOREWORD
The Environmental Protection Agency was created because of increasing
public and government concern about the dangers of pollution to the health
and welfare of the American people. Noxious air, foul water, and spoiled
land are tragic testimony to the deterioration of our natural environment.
The complexity of that environment and the interplay between its components
require a concentrated and integrated attack on the problem.
Research and development is that necessary first step in problem solution
and it involves defining the problem, measuring its impact, and searching
for solutions. The Municipal Environmental Research Laboratory develops new
and improved technology and systems for the prevention, treatment, and
management of wastewater and solid and hazardous waste pollutant discharges
from municipal and community sources, for the preservation and treatment of
public drinking water supplies, and to minimize the adverse economic, social,
health, and aesthetic effects of pollution. This publication is one of the
products of that research; a most vital communications link between the
researcher and the user community.
This report presents a summary of treatment techniques that may be of use
in the solidification and/or chemical stabilization of industrial sludges con-
taining hazardous materials. The report explores one possible option which
testing techniques may demonstrate can be used in containing hazardous wastes.
This report is issued for information purposes only and should not be inter-
preted as an endorsement of or recommendation for the use of these processes.
Francis T. Mayo, Director
Municipal Environmental Research
Laboratory
iii
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ABSTRACT
Stabilization/solidification or fixation is a process for treating in-
dustrial solid wastes (primarily sludges) that contain hazardous constituents
to prevent dissolution and loss of toxic materials into the environment. Most
of these treatment processes are designed to produce a monolithic solid of
low permeability. Some of the stabilization/solidification processes can fur-
ther control the loss of toxic materials by (a) reacting chemically with the
toxic constituents to produce new inert solid compounds that bind the poten-
tial pollutants into stable crystal lattices; (b) controlling the pH and redox
potential so that toxic compounds are maintained under conditions where the
materials have minimum solubility; (c) covering the solid waste material with
a coating that does not react with the waste, but prevents water from reach-
ing the material.
Present solidification/stabilization systems can be grouped into seven
classes of processes.
a) Solidification through cement addition.
b) Solidification through the addition of lime or other pozzolanic
materials.
c) Techniques involving embedding wastes in thermoplastic materials
such as bitumen, paraffin or polyethylene.
d) Solidification by addition of an organic polymer.
e) Encapsulation of wastes in a inert coating.
f) Treatment of the wastes to produce a cementitious product without
major additions of other constituents.
g) Formation of a glass by fusion of wastes with silica.
The advantages and disadvantages of each approach is discussed. Abstracts
from technical information furnished by companies developing or marketing
solidification/stabilization processes or marketing equipment specifically for
these processes are presented.
This report was submitted in partial fulfillment of Interagency Agree-
ment No. EPA-IAG-D4-0569 by the U.S. Army Engineer Waterways Experiment
Station under the sponsorship of the U.S. Environmental Protection Agency.
This report covers work performed from June 1976 to December 1978.
iv
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CONTENTS
Foreword ill
Abstract iv
Acknowledgements vi
1, Introduction 1
Background 1
Requirements of toxic waste treatment 3
Scope of this report 4
2. Fixation Technology 5
Cement-based techniques 6
Lime-based techniques 8
Thermoplastic techniques ... 9
Organic polymer techniques 11
Encapsulation techniques . 12
Self-cementing techniques 13
Classification 14
References 16
Appendix - Sources of Fixation Technology 18
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ACKNOWLEDGEMENTS
This technology survey was conducted by the Environmental Laboratory of
the U. S. Army Engineer Waterways Experiment Station (WES) under sponsorship
of the Municipal Environmental Research Laboratory, U. S. Environmental Pro-
tection Agency.
The authors are Dr. Philip G. Malone and Dr. Larry W. Jones. Mr. Douglas
W. Thompson reviewed the manuscript and provided valuable criticism. The
abstracts presented in the Appendix are available due to the efforts of the
many companies that responded to inquiries and submitted technical information
for inclusion in this survey. The project was conducted under the general
supervision of Dr. John Harrison, Chief, Environmental Laboratory, Mr. Andrew
J. Green, Chief, Environmental Engineering Division, and Mr. Norman R.
Francingues, Jr., Chief, Treatment Process Research Branch.
The guidance and support of Mr. Robert E. Landreth, Mr. Norbert B. Scho-
maker and the Solid and Hazardous Waste Research Division, Municipal Environ-
mental Research Laboratory, U. S. Environmental Protection Agency are grate-
fully acknowledged. The diligent and patient efforts of Ms. Rosie Lott and
Ms. Maureen Smart, typists, are also gratefully acknowledged. The Director
of WES during the course of this work was COL J. L. Cannon, CE. Technical
Director was Mr. F. R. Brown.
vi
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SECTION 1
INTRODUCTION
BACKGROUND
Hazardous wastes have only recently been adequately described and given
the attention they warrant and a great deal remains to be learned about their
management and disposal. Hazardous wastes have been defined by the Environ-
mental Protection Agency (1) as wastes, or combinations of wastes, that
pose a substantial present or potential hazard to human health or living
organisms because: (a) such wastes are non-degradable or persistent in
nature, (b) they can be biologically magnified, (c) they are noxious or toxic,
or (d) they may cause, or tend to cause, detrimental cumulative effects.
In the last few years Federal and state legislation has been directed
toward insuring proper treatment, control and disposal of hazardous industrial
wastes. Emphasis has been placed upon the overall design of environmentally
sound waste disposal systems; random and uncontrolled dumping of raw wastes
is no longer an acceptable practice. Industry must concern itself with all
aspects of disposal practices including soil and geologic features of the
disposal site, runoff and groundwater contamination, bioaccumulation or bio-
degradation, and reclamation and/or final disposition of the site. The
largest step in this direction is Public Law 94-580—The Resource Conservation
and Recovery Act of 1976, which amends the earlier Solid Waste Disposal Act
to provide for a wide range of activities such as a hazardous waste regulatory
program, a call for the elimination of open dumping, and grants to certain
communities to improve their solid waste management systems.
The traditional idea that hazardous wastes can be simply dumped or diluted
has given way to the realization that all wastes ultimately are returned to
the environment. There is a finite limit on the ability of the environment
to absorbed waste materials and remain unaltered. Large expenditures of
money and manpower are being made to develop methods for the proper treatment
and/or containment of noxious and toxic wastes. Several responses to the
problem are being actively pursued under private and governmental auspices.
Deep, abandoned mines which occur in stable geologic formations are being
investigated as repositories for hazardous wastes such as long-lived radio-
active materials (2) or even for such wastes as flue gas cleaning sludges (3).
Continued controlled dumping in the deep ocean is also being considered for
many of the less noxious wastes (4). Isolating landfills with impervious
liners or landfilling noxious materials in sealed containers is currently
practiced in several special purpose landfills (5). This report is concerned
with another alternative; that of chemically fixing or structurally isolating
the hazardous materials in a solid, crystalline, or polymeric matrix so that
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the resulting monolithic solid mass can be safely handled, transported and
disposed of using established methods of landfilling or burial.
Waste fixation is for the most part synonomous with stabilization/
solidification. Chemical fixation and stabilization/solidification are general
terms used to designate processes that can be used to immobilize, isolate, or
contain industrial waste materials, especially semi-solids or sludges. Fixa-
tion usually has as one of its goals the production of a solid material from
a semi-liquid waste. The terms solidification or stabilization are usually
used interchangably although they represent different ideas.
Solidification suggests the production of a solid, monolithic mass with
sufficient structural integrity to be transported in some conveniently-sized
pieces without requiring any secondary containers. The solidification aspect
of fixation comes from a Department of Transportation (DOT) regulation that
all liquid radioactive waste material be converted into solid form (by absorp-
tion on solids, drying, etc.) prior to transportation in interstate routes.
Some fixation technology has as its goal only the solidification of wastes to
comply with this DOT regulation.
Stabilization suggests immobilization of toxic substances by reacting
them chemically to form insoluble compounds or perhaps entrapping the toxic
element or compound in a watertight, inert polymer or stable crystal lattice.
The dissolution of wastes has always been a major problem in containing a
toxic material so, much of the emphasis in stabilization has been placed in
preventing the waste from coming in contact with water or creating pH and
oxidation-reduction conditions that minimize the solubility of the toxic com-
pounds in the waste. Many fixation systems combine these two ideas by produ-
cing an impermeable mass that isolates the wastes from any surrounding water
(soil-water or groundwater) and at the same time holds the chemical conditions
(pH and Eh) of any water that does enter the solidified wastes in the region
of minimum solubility for the toxic compounds in the wastes (6).
Major Types of Toxic Industrial Wastes
In any discussion of toxic industrial wastes, the major categories that
appear are (a) flue-gas cleaning sludges, (b) waste streams containing toxic
organic materials, (c) waste streams containing toxic inorganic materials.
Flue gas cleaning (FGC) sludges are produced in scrubbing operations
designed to remove sulfur oxides and other pollutants from flue gas at power
generating or metal extraction facilities. The sludges produced are usually
a thixotropic mass of tnicrocrystals of calcium sulfite and calcium sulfate
with some flyash and are extremely difficult to dewater. Water which comes
in contact with the sludge, or which leaches through it, typically acquires
a high calcium content (500-700 mg/£) and a high sulfate content (1200-1500
mg/&). This sulfate level is well above the acceptable limits for potable
water. Depending upon the coal source or ore being processed relatively high
levels of many heavy metals are contained in, and easily leached from the FGC
sludge (3).
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By the end of this decade, flue gas scrubbers will produce 30 to 60
million tons of this sludge annually. Because of the large volume and unique
character of FGC sludges, a technology devoted exclusively to their
solidification/stabilization or fixation is rapidly developing (7). Portions
of this report will deal with waste fixation techniques tailored specifically
for use with FGC sludges. In some cases, fixation methods for FGC sludges
are adaptable to other, oftentimes more toxic sludges.
Many toxic organic wastes are used solvents or oils or organic-rich
sludges that collect in storage facilities for solvents or fuels. In some
circumstances much of this waste can be reclaimed. Where reclaiming is not
economical, the material must be disposed of by land application, incinera-
tion or burial. Unfortunately, most solidification/stabilization techniques
have not been successful in containing organics. Organics especially oily
materials interfere with the polymerization of silicate materials so the
cement or pozzolan-based fixatives tend to loose cohesion and never produce
a "set". Fixing techniques that depend on encapsulation with organic resins
encounter problems due to the solvent effects of the organic wastes. Any
fixation techniques that require that the waste be heated (as in asphalt or
plastic encapsulation procedures) often cannot be used with organic-rich
wastes because of vaporization or danger of fire.
Many companies involved with waste stabilization refuse to accept organic-
rich wastes for stabilization. Other operators will accept only limited
amounts of organics and will mix the organic waste with large volumes of
dried inorganic material that will serve as an absorbant. While theoreti-
cally it is possible to demonstrate that many toxic organics, especially
chlorinated organics, are tightly absorbed to solid phases such as clay or
char, there is not a great deal of interest in attempting to stabilize these
wastes. The ash from organic wastes or sludge is a much more easily stabili-
zed material than an unincinerated organic sludge.
REQUIREMENTS OF TOXIC WASTE TREATMENT
The ideal fixative renders the toxic contaminants chemically nonreactive
and immobile so that no secondary containment is necessary. For example,
incorporation into a stable crystal lattice would effectively isolate the
toxic material from any environmental interactions. Maintaining the pH in
the range of 9 to 11 immobilizes the majority of multivalent cations as
insoluble hydroxides. Sludges with high concentrations of particular cations
could be treated with fixatives chosen specifically to immobilize these con-
taminants. Anions, although typically much less toxic, are much more diffi-
cult to bind into an unleachable product. Chlorides and sulfates, the most
common anionic sludge components, produce only a few insoluble salts. To
contain anions such as these, the waste must be physically isolated from any
leaching medium.
To be completely effective, the waste treatment must produce a final
mixture which has physical properties such that its disposal does not per-
manently render the land unsuitable for alternate uses. However, the produc-
tion of treated wastes with soil-like character which might be suitable for
agricultural use seems highly unlikely in cases where the major contaminants
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are multivalent cations and/or high levels of salts. The action of organic
acids normally produced by the biological activity in agricultural soils would
be expected eventually to mobilize even the most tightly bound contaminants.
Such mobilized constituents would then be taken into the food chain or washed
into the groundwater. The most secure final form of treated waste is an mono-
lithic mass which has good dimensional stability, freeze-thaw resistance, low
permeability, a high bearing capacity, and resistance to attack by biological
agents. An end product such as this could be used as a foundation for
buildings or roads, or simply buried and covered over in a landfill.
The ideal fixing process, does not require extensive heat-treatment nor
large amounts of energy-intensive reactants. Also, the sludge materials
should be reclaimable by some reasonable technique as some of the sludge con-
taminants (for example, manganese and chromium) are predicted to be in a
critical supply in the future.
SCOPE OF THIS REPORT
This report is a compilation of available state-of-the-art techniques,
processes and systems for solidification and/or stabilization of hazardous
industrial wastes. Section 2 includes a brief description of the categories
of fixed materials and a compilation of their relative advantages and dis-
advantages. This is followed in the appendix by an alphabetical list of
companies that solidify or fix hazardous industrial wastes or sell fixation
materials or equipment. A very brief description of each company's fixing
process, the wastes which they can and cannot stabilize, the approximate
costs of the process, and the past experience of the company is included.
All material in this report is taken from product literature, publicly-
circulated, technical reports and correspondence with vendor companies. The
data and product claims are presented as submitted by the vendor companies.
All costs figures are only rough estimates which depend upon many broad
assumptions. Costs, where given, are only for approximate comparison between
fixation processes, and do not represent quotations for specific applications.
For further details the reader is encouraged to correspond directly with the
companies.
This compilation includes responses to questionnaires submitted to all
companies known to be active in the area of hazardous industrial waste fixa-
tion or stabilization. No endorsement of companies included is intended or
implied. Companies not appearing on this list were simply not known to the
authors or did not respond to inquiries.
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SECTION 2
FIXATION TECHNOLOGY
There exist a large number of fixation methods which are now available
or are under development, all having as their goal the safe, ultimate disposal
of hazardous wastes.. Ultimate disposal implies the final disposition of per-
sistent, nondegradable cumulative and/or harmful wastes. Three primary goals
of fixation of hazardous waste for ultimate disposal generally are: (a) to
improve the handling and physical characteristics of the waste, (b) decrease
the surface area across which transfer and loss of contained pollutants can
occur, and (c) limit the solubility of any pollutants contained in the waste.
These goals can be met in a variety of ways, but not all techniques attempt
to meet all three goals. Thus, individual fixation techniques may solve one
particular set of problems but be completely unsatisfactory for others.
The important attributes, advantages and disadvantages of the following
major categories of industrial waste fixation systems are discussed:
a) Cement-based techniques.
b) Lime-based techniques.
c) Thermoplastic techniques (including bitumen, paraffin and polye-
thylene) .
d) Organic polymer techniques.
e) Encapsulation techniques.
f) Self-cementing techniques.
g) Classification.
Since these waste fixation systems vary widely in their applicability, cost
and pretreatment requirements, many are limited as to the types of waste that
can be economically processed. Selection of any particular technique for
waste fixation must include careful consideration of the containment required,
the cost of processing, the increase in bulk of material and the changes in
handling characteristics. The design and location of any landfill that will
eventually receive the fixed waste is also a major consideration in deciding
on the degree of containment and the physical properties which will be required.
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CEMENT-BASED TECHNIQUES
Cement-based waste fixation techniques owe much of their development to
the use of this system in disposal of low-level radioactive waste (8). The
cement-waste radioactive products have been ruled as acceptable for permanent
disposal by both U. S. agencies and the International Atomic Energy Agency (9).
Common cement or "portland cement" is produced by firing a charge of lime-
stone and clay or other silicates mixtures at a high temperature. The result-
ing clinker is ground to a fine powder to produce a cement that consists of
about 50% tricalcium and 25% dicalcium silicates (also present are about 10%
tricalcium aluminate and 10% calcium aluminoferrite). The "cementation" pro-
cess is brought about by the addition of water to the anhydrous cement powder.
This first produces a colloidal calcium-silicate-hydrate gel of indefinite
composition and structure. Hardening of the cement is a lengthy process
brought about by the interlacing of thin, densely-packed, silicate fibrils
growing from the individual cement particles. This fibrilliar matrix incor-
porates the added aggregates and/or wastes into a monolithic, rock-like mass.
The success of the hardening process is affected by compounds such as sulfates,
borates, salts of some metals, and a variety of organic compounds. Five types
of portland cements are generally recognized based upon variations in their
chemical composition and physical properties (10):
a) Type I is the "normal" cement of the building trade as described
above and constitutes over 90% of the cement manufactured in the USA.
b) Type II is used in the presence of moderate sulfate concentrations
(150-1500 mg/kg).
c) Type III has a high early strength and is used where a rapid set is
required.
d) Type IV develops a low heat of hydration and is used in large mass
concrete work.
e) Type V is a special low-alumina, sulfate-resistant cement used with
high sulfate concentrations (>1500 mg/kg).
The types which have been used for waste fixation are Type I and to a much
lesser extent Types II and V.
Most hazardous wastes slurried in water can be mixed directly with the
cement and suspended solids will be incorporated into the rigid matrix of the
hardened concrete. This procedure is especially effective for wastes with
high levels of toxic metals since at the pH of the cement mixture most multi-
valent cations are converted to insoluble hydroxides or carbonates. Metal
ions may also be taken into the crystal structure of the cement minerals that
form. Materials in the waste such as sulfides, asbestos, latex, and solid
plastic wastes may actually increase the strength and stability of the waste
concrete. However, the presence of certain inorganic compounds in the hazard-
ous waste and the mixing waters can be deleterious to the setting and curing
of the waste-concrete mix (10). Impurities such as organic materials, silt,
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clay, coal or lignite may delay setting and curing of common portland cement
for as long as several days. All insoluble materials passing through a No.
200 sieve (<74 micron particle size) are undesirable as they may be present
as dust or may coat the larger particulates weakening the bond between the
particles and the cement. Salts of manganese, tin, zinc, copper and lead may
cause large variations in setting time and significant reductions in physical
strength—salts of zinc, copper and lead being the most detrimental. Other
compounds which are especially active as retarders of the setting of portland
cement include sodium salts of arsenate, borate, phosphate, iodate, sulfide—
even at concentrations as low as a few tenths of a percent of the weight of
the cement used. Products containing large amounts of sulfate (such as flue
gas cleaning sludges) not only retard the setting of concrete but, by reacting
to form calcium sulfoaluminate hydrate cause swelling and spalling in the
solidified waste-concrete. The special low alumina (Type V) cement was
developed for use in circumstances where high sulfate is encountered to pre-
vent this reaction.
A number of additives have been developed for use with cement to improve
the physical characteristics and decrease the leaching losses from the result-
ing fixed sludge. Many of the additives used in waste fixation are propriet-
ary and cannot be discussed here; but experimental work on the fixation of
radioactive waste has shown some improvement in cement-based fixation and
retention of nuclear waste by adding clay or vermiculite as absorbents (6).
Sodium silicate has reportedly been used to bind contaminants in cement fixa-
tion processes, but this additive causes an increase in volume to occur during
the setting of the cement-waste mixture (9).
Recent testing done by Brookhaven National Laboratory under the sponsor-
ship of the Nuclear Regulatory Commission indicates that a mixture of sodium
silicate and Type II portland cement produced by a rapid set with no retarda-
tion from metallic ions (11). This sodium silicate appeared to precipitate
most interfering ions in a gelatinous mass and so to remove interferences and
speed setting. Of radwastes tested only boric acid wastes produced any inhi-
bition of set in the cement mixture. The development of a gel is important
in the setting of the cement-waste-silicate mixture. Excessive mixing after
the gel forms seems to cause slower setting and lessen final strength.
Brookhaven National Laboratory developed a polymer-impregnation process
that can be used to decrease the permeability of concrete-sludge mixtures (9).
The pores of the waste-concrete are filled by soaking in styrene monomer. The
soaked material is then heated to bring about polymerization. This process
results in significant increase in the strength and durability of the concrete-
waste mixture. Surface coatings on concrete-waste composites have been exam-
ined extensively. The major problems encountered have been poor adhesion of
the coating to the waste or lack of strength in the concrete material contain-
ing the waste. Surface coating materials that have been investigated include
asphalt, asphalt emulsion, and vinyl (12). No surface coating system for
cement-based fixed material (waste-concrete) is currently being advertised.
Advantages of the cement-based fixing systems are:
a) Raw materials are plentiful and inexpensive.
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b) The technology and management of cement mixing and handling is well
known; and the equipment is commonplace. Specialized labor is not
required.
c) Extensive drying or dewatering of waste is not required because cement
mixtures require water and the amount of cement added can be adapted
to wide range of water contents.
d) The system is very "tolerant" of chemical variation. The natural
alkalinity of the cement used can neutralize acids. Cement is not
effected by strong oxidizers such as nitrates or chlorates. Pre-
treatment is.required only for materials that retard the setting
reactions of cement.
e) Leaching characteristics can be improved where necessary by coating
the resulting product with sealant.
f) Variation in the amount of cement used can produce very high bearing
capacities making the waste concrete good sub-grade and sub-foundation
material.
Disadvantages of cement-based systems are:
a) Relatively large amounts of cement are required for most fixing
processes. However this may, in part, be off-set by the low cost
of material. The weight and volume of the final product is normally
about double that of other solidification processes.
b) Uncoated cement-based products may require a well-designed landfill
for burial. Experience in radioactive waste disposal indicates that
some wastes are leached from concrete, especially by mildly acidic
leaching solutions.
c) Extensive pretreatment, or higher cost cement types or additives may
be necessary for wastes containing large amounts of impurities which
effect the setting and curing of the waste-concrete (such as borates
and sulfates).
d) The alkalinity of cement drives off ammonium ion as ammonia gas.
e) Cement is an energy-intensive material.
LIME-BASED TECHNIQUES
Waste fixation techniques based on lime-products usually depend on the
reaction of lime with a fine-grained siliceous (pozzolanic) material and water
to produce a concrete-like material (sometimes referred to as a pozzolanic
concrete). The most common pozzolanic-type materials used in waste treatment
are flyash, ground blast-furnace slag or cement-kiln dust. All of these
materials are themselves waste products with little or no commercial value.
The use of these waste products to consolidate another waste is often an ad-
vantage to the processor who can treat two waste streams at the same time.
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*>'
For example, the production of a pozzolanic reaction with power plant flyash
permits the flue gas cleaning sludge to be combined with the normal flyash
output and lime (along with other additives) to produce an easily-handled solid.
Advantages of lime-based techniques which produce pozzolan cements are
several:
a) The materials are often very low in costs and widely available.
b) Little specialized equipment is required for processing as lime is
a common additive (to neutralize wastes) in other streams.
c) The chemistry of lime-pozzolanic reactions is relatively well-known.
d) Extensive dewatering is not necessary because water is required in
the setting reaction.
The lime-based systems have many of the same potential disadvantages as
cement-based techniques:
a) Lime and other additives add to the weight and bulk to be trans-
ported and/or landfilled.
b) Uncoated lime-fixed materials may require specially designed land-
fills to guarantee that the material does not lose potential pollu-
tants by leaching.
THEEMOPLASTIC TECHNIQUES (INCLUDING BITUMEN, PARAFFIN AND POLYETHYLENE)
Development of the use of thermoplastic fixation systems in radioactive
waste disposal has led to a waste containment system that can be adapted to
industrial wastes. In processing radioactive waste with bitumen, or other
thermoplastic material, the waste is dried, heated and dispersed through a
heated plastic matrix. The mixture is then cooled to solidify the mass, and
is usually buried in a secondary containment system such as a steel drum.
Variations of this fixation system can use other thermoplastic organic materials
such as paraffin or polyethylene.
The process requires some specialized equipment to heat and mix the waste
and plastic matrix, but equipment for mixing and extruding waste-plastic is
available. The ratio of matrix to waste is generally quite high 1:1 to 1:2
fixative to waste (on a dry weight basis). The matrix and the dry waste must
be mixed at temperatures ranging from 130°C to 230°C depending on the melting
characteristics of the material and type of equipment used.
A variant of this process uses an emulsified bitumen product which is
miscible with the wet sludge. With this process the mixing can be done at
any convenient temperature below the boiling point of the mixture. The over-
all mass must still be heated and dried before it is suitable for disposal.
Ratios of emulsion to waste of 1:1 to 1:1.5 are necessary for adequate incor-
poration (9).
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In many cases, the types of waste disposed rule out the use of any
organic-based fixation technique. Organic chemicals that are solvents for
the matrix obviously cannot be used directly in this disposal system. Strong-
ly oxidizing salts, such as nitrates, chlorates, or perchlorates, will react
with organic matrix materials and cause slow deterioration. At the elevated
temperatures necessary for processing the matrix-oxidizer mixtures are extremely
flammable. Leach testing undertaken on anhydrous salts embedded in bitumen
as a matrix indicates that rehydration of the embedded compound can occur when
the sample is soaked in water and can cause the asphalt or bitumen to split
apart, greatly increasing the surface area and the rate of waste loss (11).
Some salts (such as sodium sulfate) will naturally dehydrate at the tempera-
tures required to make the bitumen plastic; so these easily dehydrated com-
pounds must be avoided in thermoplastic stabilization.
The major advantages of the thermoplastic-based disposal systems are:
a) The leach loss rates are significantly lower than those observed
with cement-based systems.
b) By disposing of the wastes in a dry condition, the overall.volume
of the waste is greatly reduced.
c) Most matrix materials are very resistant to attack by aqueous
solutions. Microbial degradation is minimal.
d) Most matrices adhere well to incorporated materials.
e) Materials embedded in a thermoplastic matrix can be reclaimed if
needed.
The principal disadvantages of thermoplastic-based disposal systems are
that:
a) Expensive, complicated equipment requiring highly specialized labor
is necessary for processing.
b) These systems cannot be used with materials that decompose at high
temperatures, especially citrates and certain types of plastics.
c) There is a risk of fire in working with organic materials such as
bitumen at elevated temperatures.
d) During heating, some mixes can release objectionable oils and odors
causing secondary air pollution.
e) The waste material to be incorporated must be dried which requires
large amounts of energy. Incorporating wet wastes greatly increases
losses through leaching.
f) The incorporation of tetraborates or iron and aluminum salts in
bitumen matrices causes premature hardening and can clog and damage
mixing equipment.
10
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g) Strong oxidizers usually cannot be incorporated into organic materials
without oxidizing reactions occurring. High concentrations of strong
oxidizers at elevated processing temperatures can cause fires.
h) Dehydrated salts incorporated in a thermoplastic matrix will slowly
rehydrate if the mixture is soaked in water. The rehydrated salt
will expand the mixture and cause the waste block to fragment.
i) The plasticity of matrix-waste mixtures may require that containers
be provided for transportation and disposal of the material.
ORGANIC POLYMER TECHNIQUES
Organic polymer techniques were developed as a response to the requirement
for solidification of radioactive waste for transportation. The most thorough-
ly tested organic polymer solidification technique is the urea-formaldehyde
(UF) system. The polymer is generally formed in a batch process where the
wet or dry wastes are blended with a prepolymer in a waste receptacle (steel
drum) or in a specially designed mixer. When these two components are
thoroughly mixed, a catalyst is added and mixing is continued until the catalyst
is thoroughly dispersed. Mixing is terminated before the polymer has formed
and the resin-waste mixture is transferred to a waste container if necessary.
The polymerized material does not chemically combine with the waste; it forms
a spongy mass that traps the solid particles. Any liquid associated with the
waste will remain after polymerization. The polymer mass must often be dried
before disposal.
Several organic polymer systems are available that are not based on urea-
formaldehyde resin. Dow Industrial Division is developing vinyl ester-styrene
polymer systems (Nuclear Binder 101) for use with radioactive waste (13). Test-
ing of this material is currently underway in the Nuclear Regulatory Commis-
sion's research programs.
The Polymeric Materials Section at Washington State University has deve-
loped a polyester resin system that is being used in solidification of radio-
active wastes. This system is currently in a pilot-plant stage in the pro-
cessing of radwastes (14, 15).
The major advantages of the organic polymer systems (especially the UF-
resin system) are:
a) Less fixative is required for solidifying the same amount of waste.
The waste-to-fixative ratio is usually about 30% greater for a
UF organic polymer system than with cement.
b) The waste material treated is usually dewatered, but not necessarily
dried. The finished, solidified polymer, however, must be dried
before ultimate disposal.
c) The organic resin used is consistently less dense (specific gravity
is approximately 1.3) than cement. The low density reduces the
transportation costs related to the fixative and fixed product.
11
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d) The solidified resin is non-flammable and high temperatures are not
required for forming the resin.
The major disadvantages of the organic resin technique, especially the
urea-formaldehyde resin system, are:
a) No chemical reactions occur in the solidification system that chemi-
cally bind the potential pollutants. The particles of waste material
are trapped in an organic resin matrix.
b) Catalysts used in the UF systems are strongly acidic and the waste-
UF mixture must be maintained at pH 1.5 + 0.5 for solidification to
occur in a rapid manner. The low pH can put many waste materials
into solution. If the pH is not lowered to 1.5, the polymerization
is slow; solids will settle out, and the fixed material will not be
trapped effectively.
c) Uncombined or "weep" water is often associated with polymerized
waste. This must be allowed to evaporate to produce a fully-cured
polymer. The "weep water" may be strongly acid and may contain
high levels of pollutants. Waste-UF mixtures shrink as they age
and will produce "weep water" during aging.
d) Some catalysts used in polymerization are highly corrosive and
require special mixing equipment and container liners.
e) The reactions producing the resin, may release fumes that can be
harmful or disagreeable even in low concentrations.
f) Some cured resins are biodegradable (especially UF-based systems)
according to several manufacturers.
g) Secondary containment in steel drums is common practice in organic
resin-waste fixation. This raises costs in processing and trans-
portation.
ENCAPSULATION TECHNIQUES
All fixation systems depend on binding particles of waste material to-
gether. To the extent to which the binder coats the waste particles, the
wastes are encapsulated. The systems addressed under encapsulation are those
in which waste that has been bonded together is inclosed in a coating or jacket
of inert material. A number of systems for coating solidified industrial
wastes have been examined by TRW Corporation (12). In most cases coated
materials have suffered from lack of adhesion between coatings and bound
wastes and lack of long-term integrity in the coating materials. After in-
vestigating many alternative binding and coating systems, TRW Corporation
produced detailed plans for what it considered the optimum encapsulation sys-
tem. The TRW-developed system has been thoroughly tested and published data
on the process are available (16).
12
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The TRW encapsulation system requires that the waste material be thorough-
ly dried. The dried wastes are stirred into a acetone solution of modified
1,2 polybutadiene for five minutes. The mixture is allowed to set for two
hours. The optimum amount of binder is 3% to 4% of the fixed material on a
dry weight basis. The coated material is placed in a mold, subjected to
slight mechanical pressure, and heated to between 120°C (250°F) and 200°C
(400 F) to produce fusion. The agglomerated material is a hard, tough, solid
block. A 3.5 mm (1/4 in.)-thick polyethylene jacket is fused over the solid
block and adheres to the polybutadiene binder. In a 360 kg to 450 kg (800-
1000 Ibs) block the polyethylene would amount to 4% of the fused waste on a
weight basis.
The major advantage of an encapsulation process is that the waste material
never comes in contact with water, so very soluble materials, such as sodium
chloride, can be successfully encapsulated. The impervious jacket eliminates
all leaching into contacting water as long as the jacket remains intact.
The major disadvantages of encapsulation are:
a) The resins required for encapsulating are expensive.
b) The process requires large expenditures of energy in drying, fusing
the binder, and forming the jacket.
c) Polyethylene is combustible with a flash point of 250°C making fires
a hazard.
d) The system requires extensive capital investments in equipment.
e) Skilled labor is required to operate molding and fusing equipment.
SELF-CEMENTING TECHNIQUES
Some industrial wastes such as the flue gas cleaning or desulfurization
sludges contain large amounts of calcium sulfate or calcium sulfite. A techno-
logy has been developed to treat these types of wastes so that they become
self-cementing (17). Usually a small portion (8-10% by weight) of the dewater-
ed waste sulfite/sulfate sludge is calcined under carefully controlled condi-
tions to produce a partially dehydrated cementitious calcium sulfate or sul-
fite. This calcined waste is then reintroduced into the waste sludge along
with proprietary additives. Flyash is added to adjust moisture content. The
finished product is a hard, plaster-like material with good handling charac-
teristics and low permeability.
The major advantages of self-cementing systems are:
a) No major additives have to be manufactured and shipped to the
processing site.
b) The process is reported to produce faster setting times and more
rapid curing than comparable lime-based systems.
13
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c) The material produced is stable, non-flammable and non-biodegradable.
d) There are reports of effective heavy metal retention perhaps related
to chemical bonding of potential pollutants (17).
e) These systems do not require completely dry waste. The hydration
reaction uses up water.
The major disadvantages of the self-cementing systems are:
a) Only high sulfate or high sulfite sludges can be used.
b) Self-cemented sludges have much the same leaching characteristics
as cement and lime-based systems.
c) Additional energy is required to produce the calcined cementitious
material.
d) The process requires skilled labor and expensive machinery in calcin-
ing waste and mixing the calcined waste with additives to produce
the fixed waste.
CLASSIFICATION
Where material is extremely dangerous or radioactive, it is possible to
combine the waste with silica and fuse the mixture into glass (18). Glasses
are only very slowly leached by naturally—occurring water, so this approach
is generally assumed to produce a safe, material for disposal without
secondary containment.
The major advantages of glassification are:
a) The process is assumed to produce a high degree of containment of
wastes.
b) The additives used are relatively inexpensive (syenite and lime).
The major disadvantages of glassification are:
a) The process is energy-intensive. A charge must be heated to 1350 C
to produce a satisfactory melt.
b) Some constituents especially metals may be vaporized before they
combine with the molten silica in the glass.
c) Specialized equipment and trained personnel are required for this
type of operation.
From the discussion of fixation techniques given above, it can be seen
that a wide variety of possible fixation systems exist and obviously not
every system is applicable to every waste in every situation. The amount and
character of the material to be stabilized, the economics involved and the
14
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properties of the disposal site all work into a decision on fixation procedu-
res to be used. By careful evaluation of economics, the hazardous nature of
the material and the containment provided by geologic and hydrologic situa-
tions at surrounding landfills it should be possible to work out a minimum
cost for responsible disposal of a particular waste.
The cost for waste fixation processes are geared to the volume of the
waste to be fixed; therefore, it may become cost-advantageous to concentrate
hazardous waste materials into a minimum volume to reduce handling and
additive requirements. When hazardous wastes are concentrated the precautions
involved in handling and transportation are necessarily increased so on-site
stabilization (or at least solidification) would be desirable. In fact,
solidification (stabilization) may simply become a unit operation to complete
the waste treatment system and the waste treatment operations could be tai-
lored to produce the hazardous residue in a minimum volume with a pH and
chemical composition that is compatible with the stabilization system that is
required to insure safe containment under specified landfill conditions.
15
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REFERENCES
1. Report to Congress by the U. S. Environmental Protection Agency. Dis-
posal of Hazardous Wastes. U. S. Environmental Protection Agency Publi-
cation SW-115, 1974. 110 pp.
2. McClain, W. C., R. L. Bradshaw and F. M. Empson. Disposal of High-Level
Solidified Wastes in Salt Mines. In: Disposal of Radioactive Wastes in-
to the Ground. International Atomic Energy Agency, Vienna, Austria, 1967.
pp. 659-559.
3. Lunt, R. R. and others. An Evaluation of the Disposal of Flue Gas Desul-
furization Wastes in Mines and the Ocean, Initial Assessment. EPA-600/
7-77-015, U. S. Environmental Protection Agency, Washington, D.C., 1977.
318 pp.
4. Environmental Protection Agency. Proposed Revision of Ocean Dumping Regu-
lations and Criteria. Federal Register, June 28, 1976.
5. Fields, Timothy, Jr. and A. W. Lindsey. Landfill Disposal of Hazardous
Wastes: A Review and Known Approaches. EPA/530/SW-165, U. S. Environ-
mental Protection Agency, Cincinnati, Ohio, 1975. 36 pp.
6. Landreth, R. E. and J. L. Mahloch. Chemical Fixation of Wastes. Indus-
trial Water Engineering, (Jul-Aug) 1977. pp 16-19.
7. Michael Baker, Jr., Inc.. State-of-the-Art of FGD Sludge Fixation.
Report FP-671, Electric Power Research Institute, Palo Alto, California,
1978. 258 pp.
8. Moore, J. G., H. W. Godbee, and A. H. Kibbey. Leach Behavior of Hydro-
fracture Grout Incorporating Radioactive Wastes. Nuclear Technology
32:39-52, 1977.
9. Holcomb, W. F. and S. M. Goldberg. Available Methods of Solidification
for Low-Level Radioactive Wastes in the United States. U. S. Environ-
mental Protection Agency, Tech. Note OPR/TAD-76-4, 1976. 39 pp.
10. Bogue, R. H. The Chemistry of Portland Cement. 2nd ed., Reinhold, New
York, 1955. 793 pp.
11. Columbo, P. and R. M. Neilson, Jr.. Properties of Radioactive Wastes
and Waste Containers. Progress Report No. 7, BNL-NUREG 50837, Brookhaven
National Laboratory, Upton, NY, 1978. 61 pp.
16
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12. Burk, M., R. Derham, and H. Lubowitz. Recommended Methods of Reduction,
Neutralization, Recovery or Disposal of Hazardous Wastes. Vol 1Y, TRW
Systems Group, Inc., June 1974. 89 pp.
13. Columbo, P. and R. M. Neilson, Jr. Properties of Radioactive Wastes
and Waste Containers. Progress Report No. 5, BNL-NUREG-50763, Brookhaven
National Laboratory, Upton, NY, 1977. 32 pp.
14. Subramanian, R. V., Wen-Pao Wu, R. Mahalingham and M. Juloori. Polyester
Encapsulation of Hazardous Industrial Wastes. Presented at "National Con-
ference on Treatment and Disposal of Industrial Waste Waters and Residues,"
Houston, Texas, April 26-28, 1977.
15. Mahalingham, R., M. Juloori, R. V. Subramanian, and Wen-Pao Wu. Pilot
Plant Studies on the Polyester Encapsulation Process for Hazardous Wastes.
Presented at "National Conference on Treatment and Disposal of Industrial
Waste Waters and Residues," Houston, Texas, April 26-28, 1977.
16. Lubowitz, H. R. and others. Development of a Polymeric Cementing and
Encapsulating Process for Managing Hazardous Wastes. EPA-600/2-77-045,
U. S. Environmental Protection Agency, Cincinnati, Ohio, 1977. 167 pp.
17. Sludge Fixation Technology, Inc. The Terra-crete Process for FGD Sludge
Fixation. Sludge Fixation Technology, Inc., Orchard Park, NY, undated.
13 pp.
18. Gilmore, W. R.' (ed). Radioactive Waste Disposal, Low and High Level.
Noyes Data Corp., Park Ridge, NJ, 1977. 363 pp.
17
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APPENDIX
SOURCES OF FIXATION TECHNOLOGY
Organizations included in this appendix are those that develop and/or
market solidification/stabilization techniques or manufacture equipment for
solidification/stabilization processes. Many of these companies hold one or
more significant patents in the waste treatment industry. This listing is not
all inclusive; many chemical landfills have fixation operations that are used
only on material to be landfilled on that site. These operations are usually
tailored only to the waste arriving at that site and stabilized specifically
for conditions at that landfill. If the stabilization operation is not
clearly defined and is not marketed off the landfill site; no attempt was made
to include the service in this list.
The information given here was obtained from answers to questionnaires
submitted to the companies involved and from company literature made available
to the authors. Data obtained from the companies with regard to strength or
leach testing of fixed material were reproduced without critical examination.
An attempt was made to present all estimates of physical properties in com-
parable metric units.
The authors have abstracted the data obtained from each vendor. Any
negotiations for the use of any particular service or process will no doubt
require more information and testing or evaluation of fixed material produced
from the client organization's waste. The physical properties and leach test
results given here may not be obtainable with every waste.
18
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a. Name of Vendor: Atcor Washington Inc.
Division of Chem Nuclear Systems, Inc.
Park Mall
Peekskill, NY 10566
Contact: M. Brownstein, Director
(914) 739-9000
b. Category of fixing process: The process is classed as a masonry-based
solidification systems (using cement).
c. Types of wastes treated: System is primarily designed to effectively
solidify typical wastes from both boiling water reactor and pressurized water
reactor nuclear power plants (which include 25% Na_SO^, 12% H BO.,, bead type
ion exchange resin and various filter media - solka floe, diatomaccous earth
and filter aid). The Atcor Radwaste Solidification System includes an in-line
mixer/feeder which fills any size container, permits inclusion of bulky items
and flushes clean with a minimum of water. All operation procedures are
remote and/or automatic.
d. Types of waste excluded from treatment: Sludges which do not combine
with cement could not be handled, however, testing for specific sludges is
required to ensure application suitability.
e. Cost of fixation: Cost is variable depending upon waste to be treated.
Dry masonry cement is added up to a volume equal to the volume of waste which
gives final product about 130% of volume of original waste. Cement cost is
approximately 9 cents per kilogram, but capital expenditure, transportation
and personnel costs will vary greatly with the individual job.
f. Leach and strength tests: Leach and strength studies showing product
acceptability for cement-based radwaste systems are numerous. The product is
a monolithic cement structure exhibiting no free water and an acceptable
leach rate for shallow-land burial.
g. Examples of past applications and current contracts: At present the Atcor
system is used solely within the commercial nuclear power industry, however,
studies are currently under way to use system for solidifying arsenic wastes
and incinerator-generated wastes. Radwaste solidification systems have been
purchased by 11 major power companies including: Northern States Power
Company (Monticello and Prairie Island), Wisconsin Public Service Co.
(Kewanee), Wisconsin Electric and Power Co. (Point Beach), Tennessee Valley
Authority (Beliefonte), Taiwan Power Co. (Chin-Shan and Kuoseng), Duquesne
Light Co. (Beaver Valley), and others.
19
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a. Name of Vendor: Chemfix, Inc.
1675 Airline Highway
Kenner, LA
(504) 729-4561
or mail correspondence to:
P. 0. Box 1572
Kenner, LA 70063
Contact: J. M. Galloway
Executive Vice-President
/or Bentley B. Mackay, Jr.
President
b. Category of fixing process: Inorganic chemical additives (cements and
soluble silicates) are mixed with the wastes to produce a gelling reaction
that is followed by hardening. A mobile treatment plant that can handle up
to 380,000 liters/10 hour shift is provided. The additives consist of up to
10% by volume of the waste. The process varies with the percent solids and
nature of the wastes. Generally the higher the percent solids the lower the
additive requirement.
c. Types of wastes treated: Most types of waste can be accepted for this
processing. The additives react with polyvalent metal ions producing stable,
insoluble, inorganic compounds. Nonreactive materials are physically entrap-
ped in the matrix structure resulting from the reaction process. Process is
usually custom designed for each type of wastes.
d. Types of waste excluded from treatment: Wastes containing certain organic
compounds, toxic anions and non-toxic but undesirable constituents are not
treated. In many cases specified pretreatment will allow solidification/
stabilization systems to be used.
e. Approximate cost of processing: Varies greatly with the % solids and
nature of the waste. (Laboratory testing to determine cost is provided.)
f. Data on leach and strength tests: Extensive leach tests have been run on
a variety of "processed" material and are available from the company. Data
available includes results of cyclic leach tests, saturation extraction tests
and non-equilibrium extraction systems. Acceptable leaching results have
been obtained from a variety of industrial wastes from automotive manufactur-
ing, electronic fabrication and other operations. The strength of fixed
material varies with the amounts of additives used. The fixed material can
vary from a soil-like mass to a solid (concrete-like) monolith with high
bearing capacity.
g. Examples of past applications and current contracts: The "CHEMFIX"
process has been applied to the following wastes: chemical and allied pro-
ducts (160 x 106 liters), petroleum refining (105 x 106 liters), transporta-
tion equipment (88 x 106 liters), primary metals (18 x 106 liters), municipal
waste water treatment, flue gas desulfurization wastes, dredging spoils, and
radioactive wastes.
"CHEMFIX" is a registered trademark of Chemfix, Inc.
20
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a. Name of Vendor: Dravo Lime Company
650 Smithfield Street
Pittsburgh, PA 15222
Contact: C. J. McCormick
(412) 566-4444
b. Category of fixing process: Dravo Lime Company's solidification additive,
Calcilox, is a dry, free flowing, light grey-colored powder of inorganic ori-
gin. It is hydraulically active and when added to the slurry improves its
handling and ultimate land disposal characteristics by imparting structural
integrity to the settled slurry. The process could probably best be classed
as pozzolanic or cementitious.
c. Type of waste treated: Calcilox is applicable to all calcium-based
scrubber waste as typically produced from coal-fired utility scrubbers.
Calcilox is also applied to many inorganic mineral processing tailings that
contain a large percentage of silica and alumina. Typical applications are
on fine coal preparation wastes and uranium mill tailings.
d. Type of waste excluded from treatment: Sludges containing organics and
sewage wastes cannot be treated.
e. Approximate cost of processing: The weight percent of Calcilox additive
dosages range from 5 to 15% of the dry slurry solids weight. Low dosages
(5-10%) are used with mechanically dewatered wastes (55 to 70% solids) and
higher dosages (10-15%) with lower solids slurries such as thickener under-
flows with 25 to 35% solids. Costs are site and process dependent: no firm
estimates are available.
f. Data on leach and strength tests: Leach data are available from field
tests on flue gas cleaning wastes and indicate reduced leach rates when com-
pared to raw sludges. Typically, leaching rates are reduced one to two
orders of magnitude below untreated wastes. The strength of the product is
controlled by the mixing ratios, but the product has a dry, clay-like con-
sistency similar to compacted clayish soil.
g. Examples of past application and current contracts: Extensive experience
has been gained through contracts with several large power plants such as the
Bruce Mansfield Power Station in Shippingport, PA, the Duquesne Light Company
Phillips Power Station, and Allegheny Power Service Company's Pleasants
Station. Current coal waste applications are at several large American
Electric Power Company mines and at smaller independent operations in Ohio
and West Virginia. Ongoing tests are being conducted with several uranium
producers in the western United States under a Department of Energy contract.
"Calcilox" is a registered trademark of Dravo Lime Co.
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a. Name of Vendor: Environmental Technology Corporation
Suite 200
1517 Woodruff Street
Pittsburgh, PA 15220
Contact: Albert R. Kupiec, Vice-President
(412) 431-8586
b. Category of fixing process: The ETC Solidification System requires com-
monly available reagents in addition to the lime which is currently used in
wastewater processes. The hazardous wastes are neutralized and solidified
resulting in a sludge which totally encapsulates the moisture and chemically
binds heavy metals and other chemicals within the sludge.
Lime is required to neutralize the acidity of the hazardous waste and to
complex most of the heavy metal cations as insoluble hydroxides. Chemistry
of the reagents is well known, but before now they had not been used in a
single system. One of the reagents acts as an ion exchange media for complete
heavy metal removal and removes excess water within the system. The other
reagents act as binders which bridge the sludge particles and increases the
physical strength and load-bearing capacity of the final sludge. The final
sludge produced is soil-like in appearance.
c. Types of waste treated: The hazardous wastes involved in the development
of the ETC system are mostly spent pickling acids from steel mills. Sulphuric
acid composes the largest amount of wastes by volume. Other types of wastes
treated include (1) hydrochloric acids; (2) other pickling acids; (3) spent
plating solutions; (4) sludge from industrial waste treatment plants; (5)
scrubber sludges; and (6) organic sludges.
d. Types of waste excluded from treatment: None listed.
e. Approximate cost of processing: Cost of neutralizing and solidification
of waste pickle liquors varies with the method of mixing and type of lime used.
Treatment with dry lime followed by ETC reagents costs 1.00 cents per liter.
Addition of lime as a slurry increases the amount of the other reagents re-
quired so that the costs rise. Other sludges can be stabilized at costs of
0.40 cents to 3.00 cents per liter.
f. Data on leach and strength tests: Leach tests were conducted in the open
in lined, V-shaped trenches fixed with perforated plastic pipe which directed
all leached liquid into plastic collection buckets. After about one month
the leachate from 10 different sludges had from 1000-5000 mg/1 total dissolved
solids, 500-800 mg/1 S04 and 150-600 mg/1 Cl. Analysis for heavy metals
showed less than 0.01 mg/1 of nickel, zinc, iron, chromium and manganese.
Only copper was present at 0.03-0.04 mg/1 levels. Hardness (i.e. physical
strength) is a function of the total amount of solids present and the quan-
tity of reagents added.
g. Examples of past applications and current contracts: None reported.
22
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a. Name of Vendor: Envirotech
3000 Sand Hill Road
Menlo Park, CA 94205
Contact: David L. Keaton, Vice-President
NOTE: For information on treatment of S02 sludges contact:
Walter Renburg, Jr.
Air Group/Pittsburgh
Envirotech Corporation
Two Airport Office Park
400 Rouser Road
Pittsburgh, PA 15108
b. Category of fixing process: The process is sodium silicate and cement-
based. (U. S. Patent 3,837,872) Envirotech is the exclusive licensee in the
field of fixed treatment units for National Environmental Control, Inc.
(parent company of Chemfix Corporation),
c. Types of waste treated: Details available from company.
d. Types of waste excluded from treatment: Details available from company.
e. Approximate costs of processing: Figures available from company.
f. Data on leach and strength tests: Can be obtained from company.
g. Examples of past applications and current contracts: Contact company
directly.
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a. Name of Vendor:
I. U. Conversion Systems, Inc.
115 Gibraltar Road
Horsham, PA 19044
Contact: Norman F. O'Leary, Vice President, Marketing; or
Richard W. Patton, Industrial Sales Manager
(215) 441-5920
b. Category of fixing process: The IUCS Poz-0-Tec process utilizes fly ash
and other additives. The Poz-0-Tec chemistry is a combination of two simul-
taneous reactions: a -rapid reaction that occurs between the soluble salts
present in fly ash and the lime and alumina that is found in the fly ash glass;
and a slower pozzolanic reaction that occurs between the silica in the fly ash
and lime. the latter reaction occurs over a period of months.
c. Types of waste treated: This solidification system was developed initial-
ly for the electric utility industry for S02 scrubber sludge stabilization.
Four million tons of FGC sludge is treated by this process in a single year.
Conversion Systems has also successfully stabilized and tested electro-
plating wastes, steel mill wastes, and chemical process wastes. Based upon
these results, the process can stabilize or encapsulate wastes having the
potential of leaching salts or heavy metals into the environment.
d. Wastes not suitable for treatment: Some organic wastes.
e. Approximate cost of fixation: Each waste must be evaluated for each
client by Conversion Systems. Several alternative methods are available
which result in somewhat different scopes of service. Preliminary cost esti-
mates for processing sludges usually fall in the range of 1 to 7 cents per
liter of waste. Some parameters influencing this range are quantity to be
processed, water content, waste toxicity, equipment redundancy, desired
methods of operation and scheduling requirements.
f. Leach and strength tests: Physical and environmental properties of
Poz-0-Tec improve with time as the pozzolanic reactions proceed. The cementi-
tious reaction produces a monolithic mass of low permeability which is subject
to surface leaching only. The following is a compilation of typical struct-
ural properties of Poz-0-Tec stabilized material:
Wet density
Dry density
Moisture content
Cohesion
Unconfined compressive
strength
Permeability coefficient
Allowable bearing capacity
Stable fill slope
Saturation
1360-1600 kg/m3 (85-100 Ib/cu ft)
1040-1360 kg/m3 (65-85 Ib/cu ft)
25-50% moisture
>95.7 x 10%/m2 (>2000 Ib/sq ft)
>1^2 x 10%/m2 (>25 Ib/sq ft)
10 6 to 10 8 cm/sec
2.87 x 105N/m2 (3 tons/sq ft)
2 horizontal to 1 vertical
incomplete
24
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Poz-0-Tec stabilized sludge may occupy more volume that the unstabilized
sludge, but any increase in material is offset by the weight reduction brought
about by dewatering the sludge before treatment and the greater heights to
which the fixed sludge pile can be built in the disposal area.
g. Examples of past applications and current contracts: Conversion systems
currently has contracted to fix 8 million metric tons of S09 scrubber sludge
produced at eleven electric power plants in the U. S. It is also stabilizing
all wastes from an SO- scrubber and water treatment plant of a large battery
manufacturer.
The company is also developing alternative disposal applications where
the physical characteristics of the fixed sludge can be used to advantage.
Poz-0-Tec stabilized materials have been used as a base parking lot and road
beds. Cast Poz-0-Tec blocks are currently under study for use in constructing
artificial reefs.
Poz-0-Tec is a registered trademark of I. U. Conversion Systems, Inc.
25
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a. Name of Vendor: Newport News Industrial Corp.
230 41st Street
Newport News, VA 23607
Contact: J. R. May, Manager} Radwaste Management Systems
(804) 380-7761
Newport News Industrial Corporation is primarily involved with volume reduc-
tion and waste handling techniques for radioactive materials. They have
broad experience with producing compact wastes that are compatible with soli-
difying agents such as urea-formaldehyde, water extendable polyesters and
bitumen. They are currently in the process of developing a new solidification
method applicable to hazardous chemical wastes including radwastes.
b. Category of fixing process: Not available.
c. Type of waste treated: Not available.
d. Type of waste excluded from treatment: Not available.
e. Approximate cost of processing: Not available.
f. Data on leach and strength tests: Not available.
g. Examples of past application and current contracts: Process still in
developmental stage.
26
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a. Name of Vendor: Ontario Liquid Waste Disposal, Ltd. or
Canadian Waste Technology, Inc.
160 Torbay Road
Markham, Ontario L3R-1G6
Canada
Contact: David Krofchak, President, Canadian Waste Technology, Inc.
(416) 495-9502
b. Category of fixing process: The solidification process is based upon the
production of stable silicate compounds analogous to natural geologic
materials.
c. Type of waste treated: All inorganic wastes from heavy, medium and light
industries such as waste pickle liquor, plating wastes, etc., containing
acids, chromium, copper, iron, magnesium, manganese, nickel, zinc, cadmium,
lead, mercury, vanadium, chlorides, sulphates, phosphorous and virtually any
inorganic chemical or combination thereof. Specialized applications have
been designed to treat mine tailing wastes and sewage sludges from primary
and secondary treatment plants.
d. Types of waste excluded from treatment: The process is ineffective
against some organic wastes, but organic wastes of up to 20% of the volume
of the formulated inorganic wastes have been treated successfully on a case
to case basis.
e. Approximate cost of processing: Each location where wastes are treated
has different costs depending upon quantity of wastes and the method of
operation. However, costs of approximately $8.00 per cubic meter ($6.00 per
cubic yard) or 0.8 cents per liter (3 cents per gallon) are easily achieved
(August 1977). This price assumes no cost for removal of solidified material
from the site. No apparent increase in fixed material to raw sludge volume
has been found.
f. Data on leach and strength tests: Extensive strength and leach tests
have been made by the company; those cited below were in cooperation with the
Ontario, Canada, Ministry of the Environment, Pollution Control Branch, Indus-
trial Section (from a paper entitled "An Assessment of a Process for the
Solidification and Stabilization of Liquid Industrial Wastes, 1976, by G. A.
Kerr, Q.C., Minister) the conclusions of this report were:
(1) The solidification process appeared to hold and stabilize most of
the heavy metals contained in the liquid (acidic metal-bearing liquid indus-
trial wastes). Heavy metal values in the leachates (laboratory and field)
were commonly below 1 mg/liter.
(2) Leachates from the testing of processed material contained high
concentrations of dissolved solids.
(3) The bulk of the common heavy metals present in the waste were re-
tained in the processed material during extended period of leaching with
27
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distilled water when considered on a mass basis. Losses of heavy metals
were relatively minor.
(4) Landfilling may be used to dispose of the processed material pro-
viding adequate facilities are available for the collection and treatment of
leachate and run-off. The concern over dissolved solids contamination will
dictate the adequacy fo the facilities required.
Material with up to 20.7 x 106 N/m2 (3000 psi) unconfined compres-
sive strength has been produced, but for reasons of cost, the end product is
generally of low strength.
g. Examples of past applications and current contracts; Currently over
380,000 liters/day (100,000 gpd) are being treated at a treatment site in the
city of Hamilton, Ontario. The fixed material is being used as a cover for
the sanitary landfill. Negotiations are currently underway with companies in
the United States and in Canada for the licensing of the technology to oper-
ate similar sites and many cases to treat company wastes on site.
28
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a. Name of Vendor: Polymeric Materials Section
Department of Materials Science and Engineering
Washington State University
Pullman, WA 99164
Contact: R, V. Subramanian
(509) 335-6784
NOTE: The Department of Materials Science and Engineering, Polymeric
Materials Section is not a vendor of the raw materials and equipment necessary
for fixation, but has extensive experience and developmental expertise in the
polyester encapsulation of hazardous wastes. In cooperation with members of
the Department of Chemical Engineering, this technology has successfully been
developed through the pilot plant stage.
b. Category of fixing process: An organic polymer (polyester resin) is used
to solidify the wastes.
c. Types of waste treated: Although very broadly effective, the process
appears to be quite effective for low-level radioactive wastes, metal ion
wastes, cyanides, arsenic wastes, and some specific organic wastes such as
kepone, PCB, and some Pharmaceuticals.
d. Type of waste excluded from treatment: The process is not effective on
very highly acidic sludges (especially at pH less than 1.0).
e. Approximate cost of processing: The price of polyester resin is about
$1.00/kg (45 cents/lb). Since the maximum volume fraction of close-packed
spheres is 74%, the minimum amount of resin which must be added to the waste
is about 25% by volume. The fixed waste is usually 133% to 175% of the
volume of the unfixed waste.
f. Data on leach and strength tests: Tests made using a fixed product encap-
sulating 60% by weight of a 24% sodium sulfate solution indicated compressive
strength of 15.0 x 106 N/m2 (2180 psi). Irradiation with 600 Mrad gamma
radiation actually increased the compressive strength to 20.7 x 106 N/m2
(3000 psi). The strength of the product is dependent upon the type, propor-
tion and form-of waste incorporated.
The leachabilities of Co-58, Sr-85, and Cs-134 from a similar encapsulated
sodium sulfate waste were 3.2 x 10 3, 3.5 x 10~3, and 5.9 x 10~3 cm, respec-
tively over a period of 120 days. The leach curves leveled off at this value
after an initial rise in the first 20 days. Thus, the leachability, after
the initial dissolution of surface material, was practically negligible.
g. Examples of past applications and current contracts: Ontario Hydro,
Toronto, Ontario is pursuing this process for radwaste encapsulation.
29
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a. Name of Vendor: Protective Packaging, Inc. (NECO)
A subsidiary of Teledyne Corp.
328 Production Court
Jeffersontown, KY 40299
Contact: Charles Jay
(502) 491-8300
b. Category of fixing process: The company sells an organic polymer solidi-
fication system.
c. Types of waste treated: Company has extensive experience with nuclear
wastes, both in solidification and disposal. Details are available from the
company.
d. Types of waste excluded from treatment: Consult company directly.
e. Cost of fixation: Information available from company.
f. Leach and strength test: Details on testing with radwastes available.
g. Examples of past applications and current contracts: Available directly
from company.
30
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a. Name of Vendor: Sandia Laboratories
Albuquerque, NM 87115
Contact: R. L. Schwoebel, Manager
Chemistry and Materials Characterization Department
(505) 264-4309, ext. 5820
NOTE: Sandia's waste management program is wholly oriented toward
stabilization of radiation containing wastes (July 1975).
b. Category of fixing process: The Sandia Solidification Process project
is a feasibility study of the solidification of solid wastes. Fission pro-
duct cations and actinides undergo ion exchange on inorganic ion exchangers
being developed at Sandia Laboratories. These ion exchangers are hydrous
oxides of Ti, Zr, Nb, Ta.
c. Type of waste treated: The process is designed for high-level radio-
active wastes such as the high level waste stream resulting from commercial
nuclear fuel reprocessing was well as caustic defense waste streams with
high salt (NaNO ) contents.
d. Type of waste excluded from treatment: The high cost of process precludes
low value, low hazard wastes.
e. Approximate cost of processing: Cost estimates for continuous column
flow systems are comparable to glassification processes. Periodic batch
processing would probably be cheaper than glassification.
f. Data on leach and strength tests: The final product, subsequent to ion
exchange, could be fired to produce a ceramic product (mixed titanates and
titania) having leach rates as much as an order of magnitude lower than that
of borosilicate glass stabilized waste.
g. Examples of past applications and current contracts: Process in feasi-
bility study stage only.
31
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a. Name of Vendor: Sludge Fixation Technology, Inc.
227 Thorn Avenue
P. 0. Box 32
Orchard Park, NY 14127
Contact: Richard E. Valiga
(716) 662-1005
b. Category of fixing process: The Terra»Crete process is a "self-cementing
process" based on the production of a cementitious material from calcium
sulfite hemihydrate or calcium sulfate. A portion of the sulfite/sulfate
sludge stream is dried and calcined to produce a cementitious agent. This
material and other additives (as needed) are introduced into the waste stream
and react to form a hard, low permeability mass from the sludge.
c. Types of waste treated: The system is primarily designed to operate with
sulfite/sulfate-based sludges produced from S02 stack scrubbing operations
but is adaptable to other situations where calcium sulfite/sulfate sludges can
be obtained.
d. Types of wastes excluded from treatment: Not specified.
e. Cost of fixation: A flue gas cleaning sludge would cost between $2.00 -
2.75 per ton for fixation.
f. Leach and strength tests: Data on leaching of antimony and lead-rich
flue gas cleaning sludge shows <0.01 ppm lead in the leach liquid. The un-
confined compressive strength obtained from the Terra»Crete material depends
on the amounts of additive used, but data showing strengths from 9.57 x 10^
N/m2 (200 lbs/ft2) to 5.74 x 10$ N/m2 (12,000 lbs/ft2) are available. Per-
meabilities are on the order of 10~° to 10"' cm/sec.
g. Examples of past applications and current contacts: None specified.
Terra«Crete is a registered trademark of Sludge Fixation Technology, Inc.
32
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a. Name of Vendor: Southwest Research Institute
8500 Culebra Road
P. 0. Drawer 28510
San Antonio, Texas 78284
Contact: John M. Dole, Manager
Process Research & Engineering
NOTE: Southwest Research Institute (SRI) is a cntract research organi-
zation and as such is not marketing processes or products.
b. Category of fixation process: Two fixation processes have been developed:
(1) SRI has developed a thermoplastic epoxy system that combines the
better features of thermosetting epoxy system with the better features of
thermoplastic systems. Low-cost extended epoxy resins and hardeners which
are solids at ambient temperatures are heated (204°C) where they become
low viscosity liquids. They are then combined and mixed with heated fillers
or aggregates and discharged. They set instantly as thermoplastic materials
and then cure as a thermosetting material to provide the typical physical
property features of epoxy containers. These epoxy materials can be used as
coatings for other fixation processes.
(2) Three different systems using sulfur have been developed for indus-
trial sludge stabilization. These systems are: (a) a modified sulfur process
where sulfur is used as a binder for the toxic sludge to produce a concrete-
like material. Since sulfur melts at about 120°C, the sludge must be heated
and dried before processing. Because of the brittle nature of sulfur, a
modified form is usually found to be superior for concrete applications;
(b) the plasticized liquid sulfur system is a new development in which sulfur
is modified to the extent that is can be used as a substitute for asphalt;
(c) the third process is sulfur impregnation. Sulfur has been used prev-
iously as an impregnation agent for concrete, gypsum, porous brick, tile
and mud block. In addition to filling the voids to reduce water absorption,
considerable strength improvements also result. This system is of use in
increasing the strength and leach resistance of sludge fixed by other methods
such as concrete admixing. Most of the sulfur composite work listed above is
still in the "developmental stage.
c. Types of wastes treated: Not fully determined.
d. Wastes not suitable for treatment: Not fully determined.
e. Approximate cost of fixation: Not determined.
f. Leach and strength tests: Not yet available.
f. Examples of past applications and current contracts: Currently in
development and testing phase.
33
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a. Name of Vendor: Stabatrol Corporation
1402 Conshohocken Road
Norristown, PA 19401
Contact: Richard E. Valiga
(215) 279-3992
b. Category of fixing process: The Terra*Tite process involves the addition
of cementitious materials to the waste sludge to produce a concrete-like
material.
c. Types of waste treated: Most industrial wastes can be treated. The
Terra»Tite process has great technical flexibility.
d. Types of wastes excluded from treatment: None specified.
e. Cost fixation: None specified.
f. Leach and strength tests: Permeabilities on the order of 10 7 cm/sec are
obtained. Leaching is insignificantly low. Terra-Tite material has shown
unconfined compressive strengths up to 4.78 x 105 N/n? (5 tons/sq ft).
g. Examples of past applications and current contacts: Heavy metal sludges,
50,000 tons; heavy metal salt cake, 10,000 tons; contaminated soils, 5,000
tons.
Terra-Tite is a trademark of Stabatrol Corporation.
34
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a. Name of Vendor: Stablex Corporation
Suite 112
2 Radnor Corporation Center
Radnor, PA 19087
Contact: John Scofield
(215) 688-3131
b. Category of fixing process: The patented technology, described as
Sealosafe, involves adding two silicate-based powders to the waste which is
dissolved or dispersed in water thereby producing a slurry and the slurry
sets into a rigid, rock-like cast. Due to its physical and chemical form,
this mass is referred to as synthetic rock.
The physical and chemical interactions which take place simultaneously
are referred to as the mechanism of crystal capture. Up to ten additional
ingredients are also used, depending upon the type of waste to be treated,
to enable the cyrstal capture mechanism to operate under optimum conditions.
c. Types of wastes treated: The process is suitable for:
(1) All inorganic wastes.
(2) Organic wastes which can be homogenously incorporated into an aqueous
phase either by dissolution, suspension, or absorption.
(3) Wastes in (1) or (2) above in liquid, solid, or sludge form, includ-
ing contaminated articles such as filter cartridges, clothing, rubber boots,
etc.
(4) The process is exceptionally successful in treating all heavy metals,
arsenic, mercury and asbestos. The process also deals with anionic wastes
such as fluoride, chloride, etc.
d. Wastes not suitable for treatment: The process is not suitable for soli-
dification of:
(1) Oils, solvents, and greases which are not miscible with an aqueous
phase.
(2) Very large quantities of water with minimal amounts of toxic
ingredients.
e. Approximate cost of fixation: In typical applications one ton of waste
would yield 1.15 to 1.4 tons of end product, called Stablex. The volume
increase in this weight increase is between 5% and 10%.
Precise cost estimates were not possible because of the different proper-
ties of the wastes to be treated. Experience indicates an extremely broad
range of between $5.00 to $350.00 per ton depending upon the type, quantity
and complexity of the waste involved.
35
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f. Leach and strength tests: Extensive experience and information is pro-
vided by the company. The product, Stablex, is 10 times less permeable than
concrete. Leaching tests in which fixed samples are ground to a fine powder
and totally immersed and wetted in ten-times their weight of distilled water
for one hour indicate that very little material is lost to the water. One
example using a solid waste fixed by the process and hardened for three days
(and containing 39,000 ppm copper, 46,000 ppm zinc, and 42,000 ppm chromium)
lost less than one ppm of these toxicants. The product, Stablex, has an
unconfined compressive strength about equal to that of the grouts used for
void filling and soil stabilization but much lower than concretes and mortars.
g. Examples of past applications and current contracts: A treatment center
near Birmingham in the United Kingdom has a current throughput of 200,000
tons of waste per year (its capacity was increased from 70,000 tons per year
in 1978). Another treatment center near London, U. K., was commissioned in
1978 with a capacity of 400,000 tons per year. Both plants operate as re-
gional treatment plants handling a variety of wastes from different sources.
Construction of two plants in Japan and the first plant in the U. S. has been
scheduled to begin in 1979.
The Sealosafe Service includes a process protected by patents and patent
applications in the United States and overseas and Sealosafe and Stablex are
trademarks of the Stablex Group of Companies.
36
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a. Name of Vendor: TJK, Inc.
7407 Fulton Avenue
North Hollywood, CA 91605
Contact: Masaaki Endo, General Manager
(213) 875-0410
NOTE: This company has contracted to market the Takenaka Sludge Treatment
(TST) System (Takenaka Komuten Co., Osaka, Japan) in the U. S. Studies con-
ducted by EPA on Kepone and arsenic disposal problems are now underway.
b. Category of fixing process: Hardeners are principally cement-family or
cement-based materials. In addition, special additives are used for stabi-
lizing harmful substances. Several series of hardeners are used depending
upon the specific mud or sludge to be treated.
c. Type of waste treated: The TST system is a technique for solidifying
mud of comparatively high water content or sludge discharged from factories
and plants. It transforms the material into a form easy to handle for utili-
zation in land reclamation and pollutant control. Treatable material can be
widely dispersed, settled sludge or sludge obtained directly from the factory
or plant. In the case of sludges with toxic substances such as mercury,
chromium and cadmium, TST treatment stabilizes and chemically fixes these
harmful substances.
d. Types of waste excluded from treatment: Two types of sludges tested but
found unsuitable are sludge produced from a wool scouring plant (greater than
20% fats and oils) and sludges containing large amounts of paint wastes.
e. Approximate cost of processing: Costs of processing will, of course,
vary with the type of sludge and additives required but will run from about
$10/m3 ($8/yd3) to $20/m3 ($16/yd3). These estimates do not include trans-
portation or disposal. Volume increase upon treatment is from 1.05 to 1.15
times pretreatment volume.
f. Data on leach and strength tests: Extensive leach testing has been
carried out by the company. In their standard leach test, the treated sludge
is ground to a particle size between 0.5 mm and 5 mm. This powder is then
mixed with distilled water and adjusted to pH of between 5.8 and 6.3 with
HC1 or C02. The final mixture (100 ml) is 10% (weight/volume) sludge to
water. This mixture is stirred for 6 hours at room temperature and 1 atmos-
phere and then filtered or centrifuged before analysis. Results of tests
made with a wide variety of sludges and muds containing a wide variety of
toxic metal ions show that only low levels of pollutants are released even
in the relatively severe leaching test. (Ions reported and their maximum
allowable concentrations: Alkyl-Hg and Hg, no detectable; Cd, 0.3 mg/&;
Pb, 3 mg/£; organic-P, 1 mg/£; Cr~6, 1.5 mg/£; As, 1.5 mg/A and CN, 1 mg/£.)
Unconfined compressive strength varies widely with the type of sludge and
kind and amount of additives used, but values of 5-10 x 10^ N/nr2 are not
unusual with 20% (w/v) additives.
37
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g. Examples of past applications and current contracts: Twenty-six projects
have been completed since 1973. Seventeen projects involved deposits under
water (46,000 m3), seven involved factory discharges (14,500 m3). in the
majority of these projects toxic substances were successfully contained.
38
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a. Name of Vendor: Todd Shipyards Corporation
Research and Technical Division
P. 0. Box 1600
Galveston, Texas 77553
Contact: C. E. Winters, Jr., Sales/Marketing Representative
(800) 231-2868/2869 (713) 744-7141
b. Category of fixing process: The organic polymer product called "Safe-T-
Set", is a non-toxic, non-hazardous, powdered, thixotropic thickner which is
effective with concentrated wastes as well as liquids. Safe-T-Set solidifies
into a homogenous mix with no liquid displacement. It is not a urea-
formaldehyde formulation.
c. Types of waste treated: This product was designed specifically for indus-
trial radioactive waste sludges. Tests have not been made with general
industrial wastes at this time (Dec 1978).
d. Type of waste excluded from treatment: No extensive tests have been made.
e. Approximate cost of processing: Costs will vary with the amount of addi-
tive used to solidify the mass. Typical data given by the company indicate
that 6 to 20% Safe-T-Set are typical and give hardening time of 14 to 3
minutes respectively at 21°C. The cost of Safe-T-Set is approximately
$6.60/kg in 500 kg quantities (4/77). Additive costs (at 10%) would be
approximately $600 per ton of fixed waste.
f. Data on leach and strength tests supplied by the company: Extensive
leaching and strength tests are reported by the company. These tests were
conducted with simulated radioactive wastes and were designed to prove that
Safe-T-Set, when mixed with radioactive liquid waste, would minimize activity
release if container integrity was lost during transportation or after
disposal by burial. Nine tests were performed: Escape of radioactive
material through Safe-T-Set and soil, temperature cycle tests, immersion
study of pH dependance, pH of fixation, immersion study at pH 7.0, off gas
study, stability when innoculated with bacteria, irradiation and toxicity.
g. Examples of past applications and current contracts: No information
available.
Safe-T-Set is a trademark of Todd Shipyards Corp.
39
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a. Name of Vendor: TRW Systems Group
One Space Park
Redondo Beach, CA 90278
Contact: H. R. Lubowitz, Staff Scientist
(213) 535-4321
NOTE: TRW Company has done extensive testing, development and evaluation
on fixation technology for the EPA. Data below was taken from Recommended
Methods of Reduction, Neutralization Recovery or Disposal of Hazardous Waste
by Burk, Derham, and Lubowitz or TRW, USEPA contract #68-03-0089, 21 June 1974,
and Lubowitz and others, 1977, Development of a Polymeric Cementing and En-
capsulating Process for Managing Hazardous Wastes, EPA-600/2-77-045.
b. Category of fixing process: The two types of fixation additives which
were selected for best overall potential and then studied and tested extensive-
ly were:
(1) Inorganic cements: Type 2 Portland cement, plaster of paris (calcium
sulfate hemihydrate) and lime (pure calcium oxide).
(2) Polybutadiene resins of specific stereo configurations (atactic 1, 2
polybutadiene).
All fixation techniques were tested with and without jackets of both thermo-
plastic and thermosetting resins and asphalt.
c. Types of waste treated: All types of solid wastes and sludges were felt
to be treatable, but the specific wastes treated in this study were simulated
solid wastes and sludges containing compounds of six toxic elements: arsenic,
mercury, selenium, chromium, cadmium, and lead.
d. Wastes not suitable for treatment: None given.
e. Approximate cost or processing: Process design and economics were covered
extensively in the study. Details of the design and economics of both the
organic and inorganic encapsulation processes, cost benefit analysis and a
summary of results were included. Raw material cost was the factor most
affecting the process costs and was a primary consideration in the original
selection of the fixation processes.
f. Data on leach and strength tests: Extensive tests were made and results
are available. Tests made included: mechanical testing, determination of
bulk density, surface hardness, and compressive strength; microscopic
examination of the interface between fixed specimen and the coating and leach-
ing experiments using three leaching solutions (distilled water, saturated
carbonic acid of pH 3.8 to 4.0, and 0.1M sodium sesquicarbonate solution).
Leaching was conducted at room temperature in 750 ml of leaching solution which
was mildly agitated twice per day.
g. Examples of past applications and current contracts: Not available.
40
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a. Name of Vendor: Werner and Pfleiderer Corp.
160 Hopper Ave.
Waldwick, NJ 07463
Contact: John Stewart or Richard Doyle
(201) 652-8600
NOTE: Werner and Pfleiderer Corporation manufactures equipment for in-
corporating low and intermediate level radwastes into a bitumen or plastic
matrix. Their equipment and their techniques have been used in almost all
testing of bitumen encapsulation of hazardous industrial wastes.
b. Category of fixing process: The technique used is bitumen encapsulation
or incorporation using a screw extruder.
c. Types of wastes treated: No industrial wastes are currently being
stabilized by asphalt encapsulation but, testing of asphalt encapsulated
arsenical wastes has been undertaken by the U. S. Environmental Protection
Agency.
d. Types of wastes excluded from treatment: Sludges containing strong
oxidizers such as nitrates, chlorates, perchlorates and persulfates should
not be encapsulated in asphalt. Sludge containing borates may require
special handling because they tend to cause early hardening of asphalt
materials. Salts that swell excessively on rehydration may require special
processing.
e. Cost: Not available for industrial wastes at this time. Usually wastes
are mixed on 1-to-l weight ratio asphalt to dry wastes. Asphalt of suitable
grade for blending costs 13 to 35 cents per kg. Capital, operating expenses
are presently not available for non-radioactive disposal operations. The
cost of secondary containers (55-gallon steel drums) must also be added in.
f. Leach and strength tests: According to information furnished by the
company, leach rates 100 times less than those observed with comparable
cement mix can be expected. If the microdispersed salt/asphalt mix is
coated with as little as 5 mm (0.2 in.) of pure asphalt the leach rate
was zero in distilled water over a period of two and one-half years. Strength
test data is not obtained for asphaltic mixes as they are plastic solids
that are usually placed in steel containers.
g. Examples of past applications and current contracts: Full scale radwaste
encapsulation units are in operation at Marcoule, France and Karlsruhe, West
Germany. No one is presently using similar equipment in industrial waste
processing.
41
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
REPORT NO.
EPA-600/2-79-056
2.
3. RECIPIENT'S ACCESSION NO.
TITLE AND SUBTITLE
Survey of Solidification/Stabilization Technology
for Hazardous Industrial Wastes
5. REPORT DATE
July 1979 (Issuing Date)
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
Environmental Laboratory
8. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORGANIZATION NAME AND ADDRESS
U.S. Army Engineer Waterways Experiment Station
Vicksburg, Mississippi 39180
10. PROGRAM ELEMENT NO.
1DC818, SOS 1, Task 27
11. CONTRACT/GRANT NO.
IAG-D4-0569
12. SPONSORING AGENCY NAME AND ADDRESS
Municipal Environmental Research Laboratory--Cin.,OH
Office of Research and Development
U.S. Environmental Protection Agency
Cincinnati, Ohio 45268
13. TYPE OF REPORT AND PERIOD COVERED
Interim
14. SPONSORING AGENCY CODE
EPA/600/14
15. SUPPLEMENTARY NOTES
Project Officer: Robert E. Landreth 513/684-7871
16. ABSTRACT
Stabilization/solidification or fixation is a process for treating industrial solid
wastes (primarily sludges) that contain hazardous constituents to prevent dissolution
and loss of toxic materials into the environment. Most of these treatment processes
are designed to produce a monolithic solid of low permeability. Some of the stabili-
zation/solidification processes can further control the loss of toxic materials by
(a) reacting chemically with the toxic constituents to produce new inert solid com-
pounds that bind the potential pollutants into stable crystal lattices; (b) controlling
the pH and redox potential so that toxic compounds are maintained under conditions
where the materials have minimum solubility; (c) covering the solid waste material with
a coating that does not react with the waste, but prevents water from reaching the
material. Prevent solidification/stabilization systems are grouped into seven classes
of processes. The advantages and disadvantages of each approach is discussed. Ab-
stracts from technical information furnished by companies developing or marketing
solidification/stabilization processes or marketing equipment specifically for these
processes are presented.
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.lDENTIFIERS/OPEN ENDEDTERMS
:. COS AT I Field/Group
Stabilization, leaching, sludge, wastes
Solid Waste Management
Chemical Stabilization
(Fixation)
13B
18. DISTRIBUTION STATEMENT
RELEASE TO PUBLIC
19. SECURITY CLASS (ThisReport)
UNCLASSIFIED
21. NO. OF PAGES
48
20. SECURITY CLASS (This page)
UNCLASSIFIED
22. PRICE
EPA Form 2220-1 (Rev. 4-77)
42
U.S. GOVERNMENT PRINTING OFFICE: 1979-657-060/5347
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