EPA 402-R-00-008
August 2000
TESTING STABILIZATION/SOLIDIFICATION
PROCESSES FOR MIXED WASTE
Center For Radiation Site Cleanup
Radiation Protection Division
Office of Radiation and Indoor Air
U.S. Environmental Protection Agency
1200 Pennsylvania Avenue, N.W.
Washington, DC 20460
Prepared under:
Contract No.
2W-7520-NASA
Office of Environmental Restoration
U.S. Department of Energy
Germantown, MD 20874
Office of Solid Waste and Emergency Response
U.S. Environmental Protection Agency
Washington, DC 20460
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DISCLAIMER
The following report is intended solely as guidance to Environmental Protection Agency (EPA)
and other environmental professionals. This document does not constitute rulemaking by the
Agency, and cannot be relied on to create a substantive or procedural right enforceable by any
party in litigation with the United States. EPA may take action that is at variance with the
information, policies, and procedures in this document and may change them at any time without
public notice.
Reference herein to any specific trade names, products, processes, or services does not convey,
and should not be interpreted as conveying, official EPA approval, endorsement, or
recommendation.
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PREFACE
This report contains information and data for four Stabilization/Solidification (S/S) processes:
calcium sulfo-aluminate (CSA) based-cement stabilization, magnesium phosphate (MP) based-
cement stabilization, Orthophthalic Polyester (OPE) Resin Encapsulation, and Epoxy Vinyl Ester
(EVE) Resin Encapsulation. This project was to design and develop a matrix for testing the four
S/S processes at independent laboratories using the same procedures and techniques. The subject
was tested under different conditions in a controlled, monitored and otherwise uniform
environment to provide unbiased data and information for a more accurate and comparable
analysis. This project presents an objective point of view, and no recommendations or
endorsements of an S/S process will be finalized in this report.
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This publication is the result of a cooperative effort between the EPA Office of Radiation and
Indoor Air (ORIA), Office of Solid Waste and Emergency Response (OSWER), and the
Department of Energy Office of Environmental Restoration (EM-40). In addition, this
publication is produced as part of ORIA's long-term strategic plan to assist in the remediation of
contaminated sites. It is published and made available to assist environmental remediation
professionals all over the United States.
Stephen D. Page, Director
Office of Radiation and Indoor Air
IV
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ACKNOWLEDGMENTS
Tri T. Hoang of ORIA's Center for Radiation Site Cleanup (CRSC) is the EPA project manager
for this report. Project support was provided by both DOE/EM-40 and OSWER's Office of
Remedial and Emergency Response (OERR),
EPA/ORIA wishes to thank the following individuals for their technical assistance and review
comments on the drafts of this report:
Lawnie Taylor, DOE-HQ, Environmental Restoration
Stuart Walker, EPA, OSWER, OERR
Robin Anderson, EPA, OSWER, OERR
John Austin, EPA, OSWER, OSW, HWMMD
Robbie Biyani, COGEMA Engineering Corporation
John Blanchard, EPA, Region 4
Dave Bussard, EPA, OSWER, OSW, HWID
Andrea Faucette
Steve Hoeffner, Clemson Technical Center
Paul Kalb, Brookhaven National Laboratory
Christine Langton, Westinghouse Savannah River
R. Mahalingham, Washington State University
Vince Maio, Bechtel B&W Idaho Technology Company
Irma McKnight, EPA, ORIA Product Review Officer
Asok Sarkar, University of Dayton Research Institute
Roger Spence, Oak Ridge National Laboratory
John Thies, Pressure Systems, Inc.
Charles Wilk, Portland Cement Association
The following staff from ORIA's Radiation Protection Division provided procurement support of
this project or reviewed this document:
Bonnie Gitlin, Director, CRSC
Ed Feltcorn, CRSC
Agnes Ortiz, Center for Federal Regulations
Ceia Wene, Immediate Office
In addition, special acknowledgment goes to Ron Wilhelm from ORIA's Center for Radiation
Site Cleanup, Ed Barth from ORD's NRMRL-CINC, and John Barich from EPA Region 10 for
their contributions in the development, guidance, and review of this project.
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TO COMMENT ON THIS GUIDE OR PROVIDE INFORMATION FOR FUTURE
UPDATES:
Send all comments to:
U.S. Environmental Protection Agency
Office of Radiation and Indoor Air
Attention: Testing Stabilization/Solidification Processes For Mixed Waste
1200 Pennsylvania Avenue, N.W. (6603J)
Washington, DC 20460
or
webmaster.oria@epa.gov
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ABSTRACT
The June 1996 report, Stabilization/Solidification Processes for Mixed Waste (EPA 402-R-96-
014) which was developed by the U.S. Environmental Protection Agency (EPA), contains
information and data (from the organizations that developed or use the processes) for four
Stabilization/Solidification (S/S) processes: Grout/Portland Cement Stabilization, Sulfur
Polymer Encapsulation (SPE), Polymer Encapsulation (PE), and Phoenix Ash Technology
(PAT). While these data are informative, they cannot render a true comparison between
processes because the testing for each was performed independently of the others under different
conditions and at different testing laboratories.
In the June 1996 report, ORIA of the EPA recognized these limitations, stating "...Our next
project is to design and develop a test matrix to compare...stabilization/solidification (S/S)
processes at independent laboratories..." In October 1996, the subject Testing S/S Processes For
Mixed Waste project was initiated to further understand different S/S processes and their
capabilities. This report summarizes the results of that effort.
Four sample matrices contaminated with five metals - arsenic, chromium (VI), lead, cesium and
strontium - were selected for use as surrogate waste in this study. Four S/S processes - calcium
sulfo-aluminate (CSA) based-cement stabilization, magnesium phosphate (MP) based-cement
stabilization, Orthophthalic Polyester (OPE) Resin Encapsulation, and Epoxy Vinyl Ester (EVE)
Resin Encapsulation were evaluated using leachability and durability tests. The CSA and MP
cement processes resulted in significant variable retention of arsenic, chromium and lead (largely
due to failures in pretreatment), poor retention of cesium and strontium, generally poor durability
in the treated waste forms, and low to moderate strengths. The OPE and EVE processes resulted
in generally good retention of metals, good durability, and exceptional strength in most cases.
Many opportunities for improvement in all of the processes were noted.
VII
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LIST OF TABLES
Table 1-1: Criteria for Different Waste Disposal Scenarios, LLMW 6
Table 1-2: Product Properties vs Waste Type and Stabilization Process,
Treatment Level A 11
Table 1 -3: Product Properties vs Waste Type and Stabilization Process,
Treatment Level B 12
Table 1 -4: Process Engineering Parameters vs Waste Type and Stabilization
Process, Treatment Level A 13
Table 1-5: Process Engineering Parameters vs Waste Type and Stabilization
Process, Treatment Level B 14
Table 2-1: Calcium Sulfo-Aluminate (CSA) Based-Cement Formulations 20
Table 2-2: Calcium Sulfo-Aluminate (CSA) Based-Cement Test Results ..21
Table 3-1: Magnesium Phosphate (MP) Based-Cement Formulations 34
Table 3-2: Magnesium Phosphate (MP) Based-Cement Test Results 35
Table 4-1: Orthophthalic Polyester (OPE) Resin Encapsulation Formulations 46
Table 4-2: Orthophthalic Polyester (OPE) Resin Encapsulation Test Results 47
Table 5-1: Epoxy Vinyl Ester (EVE) Resin Encapsulation Formulations 60
Table 5-2: Epoxy Vinyl Ester (EVE) Resin Encapsulation Test Results 61
Table A-l: Calcium Sulfo-Aluminate (CSA) Based-Cement Process 74
Table A-2: Magnesium Phosphate (MP) Based-Cement Stabilization 78
Table A-3: Orthophthalic Polyester (OPE) Resin Encapsulation 82
Table A-4: Epoxy Vinyl Ester (EVE) Resin Encapsulation 86
Table C-l: Original and Present RCRA LDR Metals Leaching Levels, TCLP Test 110
Table D-l: Pre-Treatment Soil Analytical Results 117
Table E-l: Post-Treatment Soil Analytical Results 123
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LIST OF FIGURES
Figure B-l: TCLP, Results Comparison, Arsenic Concentration 93
Figure B-2: TCLP, Results Comparison, Chromium Concentration 94
Figure B-3: TCLP, Results Comparison, Cesium Concentration 95
Figure B-4: TCLP, Results Comparison, Lead Concentration 96
Figure B-5: TCLP, Results Comparison, Strontium Concentration 97
Figure B-6: SPLP, Results Comparison, Arsenic Concentration 98
Figure B-7: SPLP, Results Comparison, Chromium Concentration 99
Figure B-8: SPLP, Results Comparison, Cesium Concentration 100
Figure B-9: SPLP, Results Comparison, Lead Concentration 101
Figure B-10: SPLP, Results Comparison, Strontium Concentration 102
Figure B-l 1: Wet/Dry, Results Comparison, As/Cr Spiked Waste 103
Figure B-I2: Wet/Dry, Results Comparison, Cs/Pb/Sr Spiked Waste 104
Figure B-l3: Freeze/Thaw, Results Comparison, As/Cr Spiked Waste 105
Figure B-l4: Freeze/Thaw, Results Comparison, Cs/Pb/Sr Spiked Waste 106
Figure B-l5: UCS, Results Comparison, As/Cr Spiked Waste 107
Figure B-l6: UCS, Results Comparison, Cs/Pb/Sr Spiked Waste 108
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1. COMPARATIVE SUMMARY OF PROCESSES
The June 1996 report, Stabilization/Solidification Processes for Mixed Waste (EPA 402-R-96-
014) which was developed by the U.S. Environmental Protection Agency (EPA), contains
information and data (from the organizations that developed or use the processes) for four S/S
processes: Grout/Portland Cement Stabilization, Sulfur Polymer Encapsulation (SPE), Polymer
Encapsulation (PE), and Phoenix Ash Technology (PAT). While these data are informative, they
cannot render a true comparison between processes because the testing for each was performed
independently of the others under different conditions and in different testing laboratories.
In the June 1996 report, the Office of Indoor Air and Radiation (ORIA) of the Environmental
Protection Agency (EPA) recognizes these limitations, stating "...Our next project is to design
and develop a test matrix for testing...stabilization/solidification (S/S) processes at independent
laboratories...The waste forms should be tested under different conditions in a controlled,
monitored, and otherwise uniform environment to provide unbiased data and information for a
more accurate and comparable analysis." In October 1996, the subject Testing S/S Processes For
Mixed Waste project was initiated to further understand different S/S processes and their
capabilities. The purpose of this project was to assemble and validate methodologies and
protocols for assessing the transport of radioactive and hazardous material at radioactively
contaminated sites and evaluate leachability of radionuclides and long-term durability from
various solidified materials. This was accomplished by processing contaminants and testing
various solidified materials.
The sample matrices originally considered for use in this study were Idaho National Engineering
and Environmental Laboratory (INEEL) soil, clay from clay pits near the Westinghouse
Savannah River site, synthetic soil, and synthetic sludge. The contaminants used in this study
were arsenic, chromium (VI), lead, cesium, and strontium. The S/S processes under evaluation
in this study are calcium sulfo-aluminate (CSA) based-cement, magnesium phosphate (MP)
based-cement, Orthophthalic Polyester Encapsulation (OPE), and epoxy vinyl ester (EVE)
encapsulation. The leachability tests employed in this study were the Toxicity Characteristic
Leaching Procedure (TCLP) and the Synthetic Precipitation Leaching Procedure (SPLP). The
durability tests performed were wet/dry, freeze/thaw, and unconfined compressive strength
(UCS).
In addition to the data developed during the laboratory testing program, more detailed
background information on each of the four processes was taken from the references presented.
The information so developed, along with the individual process write-ups given later in this
document, are summarized in Tables A-l through A-4 provided in Appendix A. These
summaries were made for each process, waste stream by waste stream, using the set of criteria
described in Table 1-1. They were also used as the raw data for the final comparative tables of
this section.
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In this section, Tables 1-2 through 1-5 summarize the information as concisely as possible using
"better/average/worse" comparative ratings for each criterion. In doing so, Tables 1-2 and 1 -3
compare the basic properties of waste forms produced in the four processes from six different
surrogate waste types of primary interest to EM-40 of DOE, all low-level surrogate mixed waste
(LLMW). In addition to waste form properties, various engineering parameters are compared for
each process in Tables 1-4 and 1-5. Each table provides the comparative information for a
particular regulatory/disposal scenario as described below.
1.1 WASTE TYPES
The eight waste types originally considered in this document were formulated by contaminating
each of the four waste media with two different metal formulations. They are as follows:
1. Soil samples from the Idaho National Engineering and Environment Laboratory (INEEL),
contaminated in the laboratory with arsenic and chromium
2. Soil samples from the INEEL, contaminated in the laboratory with cesium, lead, and
strontium
3. Clay from clay pits near the Westinghouse Savannah River Site (SRS), near Aiken County,
South Carolina, contaminated in the laboratory with arsenic and chromium
4. Clay from clay pits near the Westinghouse (SRS), near Aiken County, South Carolina,
contaminated in the laboratory with cesium, lead, and strontium
5. A synthetic soil mixture from a recipe provided by EPA's Risk Reduction Engineering
Laboratory (RREL) at Edison, New Jersey, contaminated in the laboratory with arsenic and
chromium
6. A synthetic soil mixture from a recipe provided by EPA's RREL at Edison, New Jersey,
contaminated in the laboratory with cesium, lead, and strontium
7. A synthetic sludge mixture from a recipe provided by the Department of Energy's Fernald
site at Fernald, Ohio, contaminated in the laboratory with arsenic and chromium
8. A synthetic sludge mixture from a recipe provided by the Department of Energy's Fernald
site at Fernald, Ohio, contaminated in the laboratory with cesium, lead, and strontium
INEEL and SRS waste media were used in this project because it was important to represent
regions from both West and East of the Mississippi. Synthetic sludge was selected to provide a
different mixture that could originate at any contaminated site. The purpose of the selecting the
synthetic soil mixture was to provide the project with baseline results. It is recognized that it
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would be desirable to include other waste media but limited resources and funding limited the
scope of this project.
Each of the four media (soils and sludge) were spiked in the laboratory with solutions of heavy
metals (arsenic, lead, and chromium) or with surrogate radionuclides (cesium and strontium) to
produce surrogate mixed waste for testing. Extensive dose/response studies were run in the
laboratory to ensure that adequate amounts of the metals in leachable form were present in the
surrogate waste after spiking. To prevent interactions among the metal solutions, two different
spiking solutions were used. One contained potassium dichromate (K2Cr2O7) and sodium
arsenate (Na2HAsO4); the other cesium nitrate (Cs(NO3)), lead nitrate (Pb(NO3)2), and strontium
nitrate (Sr(NO3)2). This resulted in a potential of eight surrogate wastes to be tested. No
significant levels of other heavy metals or of organic were present in these surrogate wastes. The
final spike concentrations used in the study were as follows:
Arsenic - 10,000 mg/kg
Chromium VI - 10,000 mg/kg
Lead-10,000 mg/kg
Cesium- 1,000 mg/kg
Strontium - 1,000 mg/kg
The contaminants selected represent contaminant categories based on their chemical behavior
and their high priority to site remediation and risk assessment activities. Also, an expanded
study was limited due to unavailable funding.
Lead provided this project with a contaminant that is a high priority to site remediation and risk
assessment activities. In addition, lead can also act as a surrogate for radioactive lead isotope.
Cesium and strontium were selected for this project because they are representative of the
chemical behavior of a cation and their radioactive forms.
Arsenic and chromium (VI) are both redox sensitive elements. Their anionic forms can be
difficult to stabilize and would provide a challenging situation for each treatment process.
Chromium (VI) present in anionic form tends not to adsorb to any significant extent to soil.
Thus, one might generalize that other anions, such as nitrate, chloride, and U(VI)-anionic
complexes, would also adsorb to a limited extent (EPA, 1999).
After this sample preparation and analysis, EPA ORIA decided that the SRS soil samples would
not go through the S/S phase of the project, since there was unnecessary sample redundancy
between the SRS soil and the synthetic soil. Therefore, all subsequent testing was performed
only on the INEEL soil, synthetic soil, and synthetic sludge samples. These six are identified
throughout this report as follows:
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1. INEEL Soil A - Soil samples from the INEEL, contaminated in the laboratory with arsenic
and chromium
2. INEEL Soil B - Soil samples from the INEEL, contaminated in the laboratory with cesium,
lead and strontium
3. Synthetic Soil A - A synthetic soil mixture from a recipe provided by EPA's RREL at
Edison, New Jersey, contaminated in the laboratory with arsenic and chromium
4. Synthetic Soil B - A synthetic soil mixture from a recipe provided by EPA's RREL at
Edison, New Jersey, contaminated in the laboratory with cesium, lead and strontium
5. Synthetic Sludge A - A synthetic sludge mixture from a recipe provided by the Department
of Energy's Fernald site at Fernald, Ohio, contaminated in the laboratory with arsenic and
chromium
6. Synthetic Sludge B - A synthetic sludge mixture from a recipe provided by the Department
of Energy's Fernaid site at Fernald, Ohio, contaminated in the laboratory with cesium, lead,
and strontium
1.2 REGULATORY/DISPOSAL SCENARIO - TREATMENT LEVEL
Each waste type/stabilization process combination can be further categorized according to one of
two treatment levels based on regulatory regimes/disposal scenarios that are applicable now or in
the near future. The two categories are:
• Treatment Level A; Treatment to the recent Universal Treatment Standards (UTS)
listed in 40 CFR Parts 148, 261, 266, 268 and 271, Land Disposal Restrictions Phase
IV: Final Rule Promulgating Treatment Standards for Metal Waste and Mineral
Processing Waste, Etc. Federal Register: May 26, 1998, V. 63, No. 100. This includes
more stringent metals leaching levels affecting non-wastewater TC Metal Waste and
non-wastewater metal constituents in soils. With regard to this project, these changes
affect only the treatment levels for chromium and lead. The arsenic treatment level is
unchanged. This treatment level is now required at present commercial mixed waste
disposal facilities. Since there is only one such facility that may receive mixed
hazardous and Low-Level Waste (LLW) presently operating in the U.S. - Envirocare of
Utah - the requirements for disposal at that facility are used in this document. These
requirements also comply with the Nuclear Regulatory Commission's (NRC) Class A
LLW minimum requirements.
• Treatment Level B: Treatment to Level A requirements above, with additional
strength and durability requirements that may be added for additional protective
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considerations. Such additional requirements are often specified for RCRA and
Superfund remedial activities, and could be applied in mixed waste remedial activities
where on-site disposal is selected. They could also be applied in the future to LLMW
disposal by the NRC1.
S/S processes for mixed waste have been developed with a set of criteria in mind, but not
necessarily the same set for all processes. For example, the OPE and EVE processes were
designed to produce moderate to high strength monoliths that would meet the NRC requirements.
On the other hand, most cement-based processes produce low to moderate strength waste forms
that may be either granular and soil-like to meet the Envirocare Waste Acceptance Criteria
(WAC) (Class A LLW) or monolithic to meet the NRC Classes B and C LLW cement waste
form requirements. The criteria used for each scenario are given in Table 1-1. Appendix C
provides more detail on the present RCRA criteria based on TCLP leachability.
1. There is a further possible treatment level - treatment to NRC requirements or
recommendations for low-level radioactive waste solidification waste form stability requirements
(Classes B and C LLW) for cement and non-cement waste forms. However, the tests specific to
this level (e.g., the ANS 16.1 leaching test) were not conducted in this project.
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Table 1-1
Criteria for Different Waste Disposal Scenarios
LLMW
Criterion
Free liquid
Particle size
Strength (UCS)
Permeability
Durability - Wet/Dry
Durability - Freeze/Thaw
Leachability (TCLP)
teachability (SPLP)
Containment of Salts
Immersion
Radiation stability
Resistance to Thermal
Degradation (Thermal
Cycling)
Resistance to
Biodegradation
Regulatory/Disposal Scenario
Treatment Level A
Envirocare WAC
No Free Liquid
Granular, not dusty, preferred
maximum size of 10 inches.
None
No specification
No specification
No specification
Present LDR Standards (1).
See also Appendix C.
No specification
No specification
No specification
No specification
No specification
No specification
Treatment Level B
RCRA LDRs
No Free Liquid
No specification
No specification
No specification
No specification
No specification
Present LDR Standards (1).
See also Appendix C.
No specification
No specification
No specification
No specification
No specification
No specification
(1) 40 CFR Parts 148,261, 266,268 and 271, Land Disposal Restrictions Phase IV: Final Rule
Promulgating Treatment Standards for Metal Waste and Mineral Processing Waste, Etc.
Federal Register. May 26, 1998, V. 63, No. 100
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1.3 EVALUATION CRITERIA
The first set of comparative tables in this section (Tables 1-2 and 1-3) gives the performance
criteria (strength, leachability, etc.) for typical waste forms made from the various waste of each
process. Each table provides this comparison for one of the two specific treatment levels. Only
those properties or criteria presently or potentially applicable to LLMW were considered. The
second set of tables (Tables 1-4 and 1-5) gives based engineering criteria (cost, scale proven,
etc.) for each combination in Table 1-2 and 1-3.
The criteria used for evaluation in this study are:
Waste Form Criteria;
• Satisfies Waste Form/Size Optimal Requirement: Different requirements apply here,
depending on the regulatory/disposal scenario. Envirocare prefers waste particle sizes
within a certain range. NRC regulations require monoliths for most waste forms. Selection
under CERCLA is based on an analysis of 9 evaluation criteria for selection of remedial
alternative (for further information, see 55 FR 8719-8723 date 3-8-90). While all S/S
processes tested can, in principle, meet any of the requirements, the comparison is based on
the ease and the cost with which a criterion is accomplished; e.g., does it require special
equipment or techniques, is it prohibitively expensive.
• Strength: This criteria is usually measured as unconfmed compressive strength (UCS) by
one of several ASTM standards. ASTM Method D 2166-98a was used in this project.
• Long-Term Durability: Generally determined as one of a variety of the following physical
tests: resistance to immersion in water; resistance to freeze/thaw; resistance to wet/dry
cycling; resistance to thermal cycling; resistance to biodegradation. However in this
project, the following tests were used:
• Wetting and Drying Compacted Soil-Cement Mixtures, ASTM Method D 559-96.
Designed to determine the resistance of compacted or hardened soil-cement materials to
repeated wetting and drying.
• Freezing and Thawing Compacted Soil-Cement Mixtures, ASTM Method D 560-
96. Designed to determine the resistance of compacted or hardened soil-cement
materials to repeated freezing and thawing.
• Radiation Stability: Also a long-term stability test, the stability of the final waste form to
radiation, either internally or externally, is of importance in mixed waste disposal.
• Leachability of RCRA Metals and Radionuclides: Two types of leaching tests are used:
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• Toxicity Characteristic Leaching Procedure (TCLP), SW846, Method 1311,
required for regulatory purposes under the RCRA Land Disposal Restrictions (LDRs)
• Synthetic Precipitation Leaching Procedure (SPLP), SW846, Method 1312, used to
determine the mobility of certain species under certain actual expected environmental
conditions, but not currently accepted in determining regulatory status.
Analysis of all leachates was done according to standard EPA and ASTM analytical methods
for the metals of interest: arsenic, chromium, cesium, lead, and strontium.
• Containment of Salts: This criteria applies to the leachability of soluble cation species such
as chlorides, sulfates, and nitrates. Waste forms that have superior metal leaching properties
may exhibit poor containment of salts. ,
• Waste Loading: The weight percentage of the final waste form that comprises the original
waste weight. The higher the value, the better, since higher loadings mean less stabilizing
reagent or resin and less total waste to package, ship, and dispose. This is especially
important in mixed waste stabilization processes, because the packaging, shipping, and
disposal of the waste is generally much more costly than the actual stabilization process.
• Volume Increase: Like waste loading, this criteria is also important in the packaging,
shipping, and disposal of the waste. Volume increase is a function not only of the process,
but of the physical form and properties of the waste and the pretreatment operations that may
be used. It is especially important in comparing processes and waste types to understand
that these comparisons cannot be made unless sufficient information is given about the
nature of the waste before and after stabilization. Unsaturated waste, such as most soils,
ashes and some salts, have bulk densities that are variable depending on the prior handling
of the waste; this is also true of some stabilized waste forms, especially those from
grout/Portland cement processes. These materials are compressible and, therefore, the
degree of compaction before and/or after treatment will strongly affect the observed volume
increase.
Engineering Criteria;
• Cost: Where data are available, treatment costs for capital, processing, chemicals/materials,
and the total cost are compared. Cost in the mixed waste field is complicated by the high
packaging, shipping, and disposal costs. This is discussed in more detail below.
• Complexity: This refers to operating the process, the ease of operation, the degree of
training required, etc.
• Robustness: This refers to the degree to which process equipment is strong and durable, the
process itself is forgiving in its operation, and able to handle various waste streams.
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• Availability of Equipment and Process Technology: Equipment refers to whether the
equipment is commercially available or easy to adapt, as opposed to the requirement for
non-standard, custom-built equipment. Process refers to whether the process can be
acquired, i.e., is it generic or must it be licensed.
• Pretreatment: Is pretreatment required to effectively operate the process on the waste in
question?
• Residuals: Does the process produce any residual streams, other than the waste form, that
may need to be treated or disposed?
• Through-put Potential: Are there practical and important limitations on the process rate
that can be achieved?
• Scale-Proven: At what scale has the process been successfully operated?
• Ease of Permitting and Public Acceptance: What will be the comparative level of
difficulty in obtaining regulatory permits and public acceptance to operate the process at a
given location?
1.4 RATING SYSTEM
The following notes and codes apply to Tables 1-2 through 1-5:
• As previously stated, the surrogate waste media were spiked with one of two different metal
solutions:
"A" - arsenic and chromium, or
"B" - cesium, lead and strontium
In most cases, the properties of the resultant S/S waste forms were not significantly different
as a result of the metal spiking solutions. When the differences were found to be significant,
the rating code carries the suffix "A" or "B," identifying to which of the two spiked samples
the code refers.
• General Rating Codes:
• Better
D Average, Typical, Intermediate
+ Worse
I Inadequate information
"A" Specific to the arsenic and chromium spiked medium, only
"B" Specific to the cesium, lead and strontium spiked medium, only
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Light Shaded Property is not applicable in this regulatory/disposal scenario
Dark Shaded Process cannot be used with that waste type.
It must be remembered that the ratings are relative within the framework of the processes
under consideration here. For the different regulatory/disposal scenarios, the relative
situation may change from one to the other, not only for the waste form parameters, but also
for the engineering parameters, such as permitting/public acceptance.
• Process Scale Proven: (may be footnoted where special circumstances apply)
C Commercial
P Pilot
B Bench
• Costs:
For uniformity, the costs were rated by $/yd3 for all processes wherever possible, with other
units in parentheses where applicable. Conversions from $/unit volume to $/unit weight are
made based on actual densities where that information is given.
Cost comparisons among processes are made on the basis of the minimum required waste
form properties for the particular regulatory/disposal scenario. For example, the organic
resin processes tend to produce high strength, durable waste forms in any case, but in
Treatment Level A, this is not required and is of no present commercial advantage.
Therefore, the minimal strength and durability values obtainable with cement-based
processes at high waste loadings are comparable, cost-wise, with the other processes' waste
loadings, rather than the property-by-property comparisons often used by those promoting
the other processes, where cement is assumed to have low waste loadings. Conversely, the
low cement waste loadings necessary to meet the potentially more stringent strength and
durability standards of Treatment Level B present a very different cost comparison picture.
An analogous situation occurs with waste containing large amounts of soluble salts.
• Availability:
For equipment, ratings are based on:
• Available off the shelf at full-scale
n Standard equipment, but may require modifications, special orders, etc.
+ Not standard equipment, or not widely available
For process, ratings are based on:
• Generic process or reagents, no license required, well known
D Patented or proprietary process or reagents, but license, license-with-purchase-of-
reagents, or licensed vendors widely available
4 Patented or proprietary process, not widely available or only limited vendors
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Table 1-2
Product Properties vs Waste Type and Stabilization Process
Treatment Level A: Treatment to Present Mixed Waste Disposal Facility Requirements, i.e., Envirocare
Meets
Waste
Form/Size
Opt.
Radiation
Stability
Leachability of RCRA Metals and Radionuclides
TCLP Test
As
Cr
Cs
Pb
D
n
n
n
D
Sr
Volume
Increase
Ratings taken from Stabilization/Solidification Processes for Mixed Waste (EPA 402-R-96-014), June 1996. Presented here for comparative purposes.
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Table 1-3
Product Properties vs Waste Type and Stabilization Process
Treatment Level B: Treatment to Possible Future Mixed Waste Disposal Facility Requirements
Waste
Type
INEEL
soil
Synthetic
soil
Synthetic
sludge
Soils
Soils
Salts
Process
CSA
MP
OPE
EVE
CSA
MP
OPE
EVE
CSA
MP
OPE
EVE
Portland
Polymer
Polymer
Meets
Waste
Form/Size
Opt.
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Strength
n
n
•
•
n
n
•
n
n
D
•
a**
n
•
•
Long Term
Durability.
Wei/
Dry
4
4
•
n
•
4
•
a
n**
4
•
•
a
•
•
Freeze/
Thaw
4
4
•
•
•
4
•
n
4**
4
•
•
n
•
•
Radiation
Stability
•
•
I
I
•
•
I
I
•
•
I
I
•
•
•
Leachability of RCRA Metals and Radionuclides
TCLP Test
As
•
4
•
•
•
4
•
•
•
4
•
•
•
•
•
Cr
4
4
•
•
4
4
•
•
4
4
•
•
•
•
•
Cs
4
4
•
•
4
4
•
•
4
4
•
•
I
•
•
Pb
•
4
•
•
•
4
n
•
•
n
n
n
•
•
•
Sr
4
4
•
•
4
4
•
•
4
4
•
•
I
•
•
Containment
of Salts
4
4
•
•
4
4
•
•
4
4
•
•
*
I
•
Waste
Loading
I
I
I
I
I
I
I
I
I
I
I
I
•
D
•
Volume
Increase
I
I
I
I
I
I
I
I
I
I
I
I
•
a
•
* Ratings taken from Stabilization/Solidification Processes for Mixed Waste (EPA 402-R-96-014), June 1996. Presented here for comparative purposes.
** Required pretreatment depends on the waste stream and contaminants
12
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2. CALCIUM SULFO-ALUMINATE (CSA) BASED-CEMENT STABILIZATION
2.1 TECHNOLOGY DESCRIPTION
The calcium sulfo-aluminate (CSA) material tested for stabilization in this study is a composite
cement used commercially for repair work and other special applications. In the United States, a
finished CSA cement is produced by intergrinding CSA clinker, Portland cement clinker, and
gypsum (anhydrite, CaSO4). In other countries, a "pure" CSA additive is ground and then
blended with Portland cement and ground anhydrite in proportions designed for the specific
application. CSA (see Conner, p. 337, (1990) for explanation of this terminology) alone is inert
and requires activation via hydration in the presence of a source of CaO and SO3. Usually this
source is from Portland cement and anhydrite (Brown, 1998.). One type of CSA cement
(Lossiter, 1948) is made by burning a mixture of 50 percent gypsum, 25 percent bauxite (native
aluminum hydroxide), and 25 percent calcium carbonate. In addition, these cements are
formulated to give the desired combination of expansiveness and high-early strength. These
cement compositions are more durable than ordinary Portland cement compositions, exhibit
excellent freeze/thaw and immersion resistance, as well as more resistance to sulfate attack. The
typical composition of CSA-type cement is 3 parts CSA, 1 part anhydrite, and 8 parts Portland
cement.
This CSA cement has the following composition:
Tricalcium silicate 20-80%
Dicalcium silicate 0-50%
Tetracalcium aluminoferrite 0-20%
Tri-calcium aluminate 0-15%
Calcium sulfate dihydrate 0-10%
Calcium carbonate 0-5%
Magnesium oxide 0-6%
Calcium oxide 0-4%
Crystalline silica 0-0.75%
The health and handling properties of the CSA cement system make it suitable for use in S/S
operations. It is low in acute or chronic oral toxicity and is not likely to be ingested due to the
physical nature of the material. Dermally, it has moderate abrasive action, but may cause
irritation, dermatitis or alkali burns in combination with water. It does present potential
inhalation problems from dust containing silica. Its abrasive action may cause severe eye
irritation. It is not flammable, so handling and storage problems are also minimal.
17
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2.2 EXPERIENCE WITH HAZARDOUS AND MIXED WASTE STREAMS
Hazardous Waste
There has been no experience found with this specific CSA S/S system in hazardous waste
treatment, although the results obtained in this project would have direct bearing on the treatment
of non-radioactive, arsenic, chromium and lead bearing soils and sludges. The patent literature
abounds with reference to operations using various combinations of sulfates, calcium aluminates
and calcium haloaluminates, often mixed with other reagents, used in hazardous waste S/S. A
few of these are referenced as examples (Uchikawa, 1979) (Ebara Infilco, 1973).
Radioactive Waste
This specific CSA S/S system is not known to have been used with radioactive waste, although it
is quite possible that it has been tested by the nuclear waste community. However, the results
obtained in this project would be applicable to cesium and strontium bearing radioactive soil and
sludges. Because of its inorganic nature, the process would likely be resistant to biological
attack and be radiation-stable.
Mixed Waste
The work done in this project is believed to be the first independent, published work on using the
calcium sulfo-aluminate based-cement system to treat different surrogate mixed wastes
containing various soil types.
2.3 PREPARATION OF TEST SAMPLES
Prior to performing mixture development, a number of screening tests were done to identify
reagent and water addition rates with each of the six waste types. Initial mixtures were based on
prior experience in treating similar waste. The best formulations, one for each waste type, were
then re-made, optimized, and subjected to the complete battery of test protocols. The surrogate
waste was chemically pretreated to reduce the solubility of certain metal ions; this pretreatment is
described in Section 6.1.
The calcium sulfo-aluminate based-cement evaluated was a product identified as Rockfast
provided by Blue Circle Cement. Mixture development was performed on the untreated samples
spiked with lead, cesium, and strontium. First, an aliquot of untreated material was placed into a
blending chamber. The specified reagent was slurried with the specified amount of tap water and
added to the untreated aliquot. The mixture was blended in a Hobart style mixture at 40 to 60
rotations per minute (rpm) for approximately 2 to 4 minutes, or until homogenous. Once the
treated material was homogeneous, the S/S surrogate waste was compacted into 2 inch diameter
by 4 inch cylindrical molds and allowed to cure in a humid environment for 10 days.
18
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Mixture development with the untreated materials spiked with hexavalent chromium and arsenic
was performed by first pretreating the materials to reduce the valence state of the chromium ion.
Pretreatment was performed by placing an aliquot of untreated material into a blending chamber.
The specified addition rate of a 20 percent phosphoric acid solution was added to the untreated
material and blended at 40 to 60 rpm for approximately 2 to 4 minutes, or until homogeneous.
Once the mixture was homogeneous, the specified addition rate of ferrous sulfate was dissolved
in the specified addition rate of tap water and added to the mixture. The mixture was again
blended until homogeneous. The addition rates of acid and ferrous sulfate were based upon past
laboratory experience in treating similar types of materials. Cement was then added directly to
the mixture and blended until homogeneous. After the mixing was completed, the treated
material was compacted into 2 inch diameter by 4 inch cylindrical molds and allowed to cure for
10 days in a humid environment.
Table 2-1 lists the optimized formulations that were used to produce samples for the testing
program. All tests and chemical analyses were done in triplicate. Standard testing and analytical
methods for S/S waste were used, as described elsewhere in this report.
Testing results for the optimized calcium sulfo-aluminate based-cement formulations shown in
Table 2-1 are given in Table 2-2.
19
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Table 2-1
Calcium Sulfo-Aluminate (CSA) Based-Cement Formulations
("Surrogate Waste" = Media + Spike)
Media
INEEL Soil
INEEL Soil
Synthetic Soil
Synthetic Soil
Synthetic Sludge
Synthetic Sludge
Spike
As/Cr
Cs/Pb/Sr
As/Cr
Cs/Pb/Sr
As/Cr
Cs/Pb/Sr
Ingredients
H3PO4(20%)/FeS04/CSA (i)
CSA (2)
H3PO4(20%)/FeSO4/CSA (i)
CSA (2)
H3P04(20%)/FeSO4/CSA (i)
CSA (2)
Surrogate
Waste
Amount
(g)
7500
7500
8000
8000
8000
8000
Reagent
Addition
(%)
5/7/15
15
5/7/15
15
5/7/15
15
Water
Addition
(%)
(3)
21
32
12
15
26
14
Total
Additions
(%)
48
47
39
30
53
29
(1) Initially, the 20% phosphoric acid was added to the surrogate waste and blended in. After homogenization, the ferrous sulfate was dissolved in the water, added and blended
in. Again, after homogenization, cement was added dry to the mixture.
(2) The cement was slurried with the water prior to addition to the surrogate waste
(3) As a percent of the surrogate waste, i.e., for a 10% addition, 10 grams of reagent or water were added to 100 grams of surrogate waste
20
-------
Table 2-2
Calcium Sulfo-Aaluminate (CS A) Based-Cement Test Results
(Data Represent The Three Samples Tested)
Test Type
As (mg/L)
UTS = 5.0
mg/L
Cr (mg/L)
UTS = 0.60
mg/L
Cs (mg/L)
Pb (mg/L)
UTS = 0.75
mg/L
Sr(mg/L)
INEEL Soil
As/Cr
Untreated
81.6
74.3
84.2
230.
241.
255.
Treated
0.15E
0.14E
0.1 5E
14.2
13.3
13.8
INEEL Soil
Cs/Pb/Sr
Untreated
9.
10.
12.
159.
87.
180.
31.6
33.8
31.9
Treated
6.0
7.4
6.0
0.035E
100
0.005E
24.7
32.2
25.7
Synthetic Soil
As/Cr
Untreated
165.
185.
162.
244.
268.
247.
Treated
0.027E
0.023E
0.024E
6.4
5.0
3.2
Synthetic Soil
Cs/Pb/Sr
Untreated
29.
28.
27.
443.
424.
426.
34.0
32.7
33.6
Treated
18.8
18.0
17.3
0.08
0.11
0.075
30.4
28.8
28.4
Synthetic Sludge
As/Cr
Untreated
1.54
1.90
3.85
248.
239.
312.
Treated
0.951
0.931
0.911
31.0
27.6
31.6
Synthetic Sludge
Cs/Pb/Sr
Untreated
58.
58.
59.
1.
3.
2.
38.0
39.4
39.9
Treated
37.7
39.5
38.6
0.49
0.25
2.0
19.5
19.3
24.6
21
-------
Table 2-2 (Continued)
Calcium Sulfo-aluminate (CSA) Based-Cement Test Results
(Data Represent The Three Samples Tested)
Test Type
As (mg/L)
INEEL Soil
As/Cr
INEEL Soil
Cs/Pb/Sr
Synthetic Soil
As/Cr
Synthetic Soil
Cs/Pb/Sr
Synthetic Sludge
As/Cr
Synthetic Sludge
Cs/Pb/Sr
Untreated Treated
N —
UTS = 5.0
mg/L
Cr (mg/L)
UTS = 0.60
mg/L
Cs (mg/L)
Pb (mg/L)
UTS = 0.75
mg/L
Sr(mg/L)
74.3
84.2
230.
241.
255.
0.27E
0.26E
9.9
11.9
10.2
9.
10.
12.
159.
87.
180.
31.6
33.8
31.9
4.2
4.2
4.2
0.46
0.45
0.62
13.0
12.8
16.3
185.
162.
244.
268.
247.
0.09 IE
0.099E
8.4
7.7
6.7
29.
28.
27.
443.
424.
426.
34.0
32.7
33.6
15.7
15.7
14.9
4.2
4.7
4.5
16.4
17.3
16.2
1.90
3.85
248.
239.
312.
3.5
2.6
19.0
16.5
19.5
58.
58.
59.
1.
3.
2.
38.0
39.4
39.9
40.6
39.7
38.8
6.9
10.1
10.6
15.0
17.0
16.4
22
-------
Table 2-2 (Continued)
Calcium Sulfo-aluminate (CSA) Based-Cement Test Results
(Data Represent The Three Samples Tested)
Synthetic Sludge
Cs/Pb/Sr
Max. Volume
Change (%)
Max. Moisture
Content (%)
23
-------
Table 2-2 (Continued)
Calcium Sulfo-aluminate (CSA) Based-Cement Test Results
(Data Represent The Three Samples Tested)
Synthetic Sludge
Cs/Pb/Sr
Max. Volume
Change (%)
Max. Moisture
Content (%)
24
-------
Table 2-2 (Continued)
Calcium Sulfo-aluminate (CSA) Based-Cement Test Results
(Data Represent The Three Samples Tested)
Synthetic Sludge
Cs/Pb/Sr
A Sample failed during test
B Sample failed to complete Cycle 1
E Estimated, result is below the reporting limit
I Indicates the presence of interferences in the test
UTS Universal Treatment Standards
25
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2.4 TESTING STAGE
The present status of CSA cement-based S/S process testing is only at the bench scale with
surrogate mixed waste. However, scale-up to pilot and commercial scale should be
straightforward, since the basic techniques and equipment are the same as those used in
conventional cement-based S/S processes and systems.
2.5 DEGREE OF TECHNICAL DEVELOPMENT
There is little experience with this specific CSA cement-based S/S process other than that
presented in this report. However, the existing, conventional Portland cement-based S/S
technology provides much of the information that would be required for further development of
this process. Pretreatment steps and additives for the chemical immobilization of various metal
species, both hazardous and radioactive, are well established in the literature and in current
commercial methods. And since the process reagents include Portland cement as the major
ingredient - CSA cement per se is a minor "additive." Therefore, the overall technology is very
similar to the conventional cement-based technology detailed in a previous ORIA report,
"Grout/Portland Cement Stabilization" (EPA, 1996).
Cement stabilization has been extensively tested with a wide range of waste containing a wide
range of contaminants at various concentrations. The survival of cement structures for millennia
is an indication of the lasting durability of this waste form, although the durability of all waste
forms, not just cement-based, is not well defined as a property or in a test. Durability usually
means the retention of the physical structure of a waste form over time or under adverse
conditions. In general, the TCLP test methodology removes this physical barrier to releasing the
contaminants; thus, durability may have little meaning for a waste form that depends on the
chemical stabilization of the contaminants. The same cannot be said of waste forms that depend
on microencapsulation (such as organic polymer binders) for the retention of the waste species.
Clearly, in such cases the stability of the binding matrix over time is important since, when it
fails, the contaminants are released.
2.6 DEGREE OF COMMERCIAL DEVELOPMENT
There has been no commercial development to date of this CSA cement-based S/S process for
mixed waste. Again, as indicated previously, experience with conventional cement-based S/S
systems should be directly applicable here.
26
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2.7 COST CONSIDERATION
Costs for utilizing the CSA cement-based S/S process for treatment of mixed waste, other than
the relatively small added cost (over that of Portland cement) due to the CSA cement addition
itself, should be close to those described previously by EPA (1996). The CSA reagent costs
about $475/ton ($0.24/lb) FOB Atlanta POE. At the ratios with anhydrite and Portland cement
given previously, the cement mixture would cost about $180/ton, compared to about $70/ton
($0.035/Ib) for Portland cement. At the mix ratios used in this project (15 percent), the added
cost over that of Portland cement would be about $17 per ton of waste treated, an increase that is
not likely to be significant in mixed waste treatment and disposal.
2.8 DATA GAPS
While a large body of data is available from conventional CSA cement-based S/S systems, there
are several areas in which further testing is recommended:
• The poor results with chromium necessitate more testing to verify that the CSA cement-
based S/S process is suitable for this metal, although it is nearly certain that either size
reduction of agglomerates, a different Cr+6 reduction approach, or longer mixing could
eliminate the problem.
• Standard lead immobilization techniques, such as the use of phosphates or carbonates,
should produce low teachability in the SPLP as well as the TCLP. This assumption must be
verified.
• Leachability of Cs and Sr must be reduced in this system. Chemical/physical techniques
already used in cement-based radioactive waste stabilization should be applicable here, but
must be verified.
• It is important to optimize the durability of this waste form. The test results for wet/dry and
freeze/thaw resistance are actually quite promising, especially for the Cs/Pb/Sr surrogate
wastes, even at low binder addition ratios. Increased binder content will likely improve
durability results, but water content and the presence of different ions also appear to have an
effect. Further investigation is needed here.
2.9 ASSESSMENT
Cementitious stabilization/solidification is one of the most widely used techniques for the
treatment and ultimate disposal of hazardous and low-level radioactive wastes. Cementitious
materials are the predominant materials of choice because of their low processing costs,
compatibility with a wide variety of disposal scenarios, and ability to meet stringent processing
27
-------
and performance requirements. Since the composition of this specific CSA cement-based S/S
process consists primarily of Portland cement, it would be expected to give similar results in
many respects.
Specifically, the results with this specific CSA cement-based S/S process are as follow:
• TCLP teachability of arsenic and lead is below the latest EPA Land Disposal Requirements
(LDRs), the Universal Treatment Standards (UTS), in most cases. One peculiarity is the low
leachability of lead from the untreated synthetic sludge. This is caused by the composition
of this medium; it contains Ca(OH)2 and MgO, both of which serve to create a good pH
regime for low-lead solubility.
• Chromium leachability is high - well above the UTS requirements. This is due to inadequate
pretreatment to reduce Cr+6 to Cr+3, since such pretreatment is the only practical way to
insolubilize Cr in the waste form. The likely cause of the pretreatment failure is the
presence of agglomerates that did not break down during mixing and which contain Cr+6
inside that can later diffuse out in the leaching test. The chromium reduction reagent -
FeSO4 - does not survive long after the cement binder is added, and so is therefore not
available to react with the Cr+6 that later diffuses out of the agglomerate.
• There are no LDR standards for cesium and strontium leachability. However, they both
leach at what appears to be high levels in all cases, exhibiting no significant reduction over
the leachability of the untreated surrogate waste. This indicates that Cs and Sr are not being
speciated in a less soluble form in the process, nor is the pH regime of the waste form
favorable for their low leachability.
• In the SPLP leaching test, leachates are at levels near or above the UTS limits. This is
caused by the difference in the pH regime created in the SPLP compared to that of the
TCLP. Chromium leachability, as in the TCLP test, was high for the SPLP test.
• As expected in a cement-based S/S process with a low binder additive ratio (i.e. 15 percent),
wet/dry and freeze/thaw durability is relatively poor overall. However three of the six forms
tested exhibited surprisingly good properties in this respect. The latter result is due to the
CSA addition.
• Unconfmed compressive strengths of the CSA cement-based waste forms are sufficient.
Strengths of the INEEL soil samples were more than adequate for any normal LDR or
remedial scenario, and the synthetic waste samples exhibited high strengths that would be
acceptable even under stringent NRC.
The high water/cement ratio used for synthetic sludge and INEEL Soil may have adversely
affected the results of the testing, as shown in Table 2.1. At a lower W/C ratios, less cement may
28
-------
have been used to achieve the desirable results. This would affect many performance factors
including waste loading and cost.
In summary, results with the CSA based S/S process were adequate for a cement-based system.
The failures in leachability are attributed directly to insufficient pretreatment for Cr+6 and an
unfavorable pH regime for the SPLP. These failures could be resolved within the pretreatment.
2.10 LIST OF REFERENCES
Brown, A.D.R. 1998. "Modifying Portland Cement Performance." Blue Circle Industries PLC.
Greenhithe, Kent, U.K.
Ebara Infilco Co., Ltd. 1973. "A Process for Treating Sludges." Japan. Patent Pub. No.
13673/73. April 28.
U.S. EPA. 1996. Stabilization/Solidification Processes For Mixed Waste. EPA402-R-96-014.
Office of Radiation and Indoor Air, Washington, DC. June.
Lossiter, H. 1948. Ing. Civils France.
Uchikawa, H. 1979. "Process for Treating a Sludge or Drainage Containing Chromium (VI)
Compounds With a Solidifying Agent." U.S. Patent 4,132,558. Jan. 2.
29
-------
30
-------
3. MAGNESIUM PHOSPHATE (MP) BASED-CEMENT STABILIZATION
3.1 TECHNOLOGY DESCRIPTION
Commercially, the proprietary magnesium phosphate (MP) cement used in this stabilization
process is a commercial product. It is described as "a one-component magnesium ammonium
phosphate rapid strength concrete repair and anchoring material" that is used for highway and
heavy industrial repair work (Master Builders, 1996). Used alone, in normal industrial use, it
exhibits a high-early strength, of approximately 2,000 psi (13.8 MPa) in one hour and more than
8000 psi (55.2 MPa) in 26 days. It is resistant to freeze/thaw cycles and deicing chemicals.
However, a number of caveats are stated by the supplier: water content is critical; other
aggregates such as sand, gravel or limestone should not be added. Since the soils and sludges in
S/S systems can be considered as types of "aggregates," this caveat may portend difficulties in
using this method for mixed waste S/S.
This MP cement has the following composition:
Silica, crystalline quartz 60-70%
Magnesium oxide (MgO) 5-15%
Fly Ash 5-15%
Ammonium phosphate 3-10%
Sodium tripolyphosphate <3%
S/S work using MP cements for mixed waste has been studied at Argonne National Laboratory
under DOE contracts (Wagh, 1994)(Singh, D. et al, 1994) using DOE surrogate - ash waste,
cement sludge, and salt waste were completed. The waste contained chromium, lead nickel,
cadmium, and cesium contaminants as well as several organic compounds. The composition of
this MP system was different than that described above and was as follows:
Mg phosphate (calcined MgO + 50% phosphoric acid)
Mg-Na phosphate (MgO + dibasic sodium phosphate + water)
Zr phosphate (Zr(OH)4 + phosphoric acid)
Waste loadings ranged from 50 to 70 percent for the Mg and Mg-Na cements, and 20 percent for
the Zr cement. Resultant strengths for the waste forms ranged from 1172 to 7572 psi, depending
on the formulation and the waste treated. Good immobilization of heavy metals in the TCLP test
was achieved with all of the systems studied: <0.2 ppm for Pb, Cd and Cr(+3), and 0.08-3.71
ppm for Ni.
The MP process used in this project should not be confused with the use of phosphates in S/S
work, primarily for treatment of lead (Krueger et al, 1991) and heavy metals in general (Eighmy,
1997). In the latter use, phosphoric acid or soluble phosphate salts, sometimes combined with
31
-------
other reagents, are used to immobilize lead in sludges and solids by converting it to an insoluble
salt, but not to cement or solidify the waste. These phosphates are usually combined with
cement or pozzolans to solidify sludges and/or to create waste forms that exhibit physical
strength and durability. It should also be noted that the resin encapsulation processes
investigated in this project used phosphoric acid as a pretreatment step for the Cs/Pb/Sr spiked
waste, while the cement processes use it as part of the pretreatment for the As/Cr spiked waste.
The health and handling properties of the MP cement system seems to be suitable for use in S/S
operations. It is low in acute or chronic oral toxicity and is not likely to be ingested due to the
physical nature of the material. Dermally, it has moderate abrasive action, but may cause severe
alkali burns in combination with water. It does present potential inhalation problems from dust
containing silica; and in contact with water, released ammonia may cause irritation. Its abrasive
action and ammonia release may cause severe eye irritation and burns. It is not flammable, so
handling and storage problems are minimal. Except for the ammonia release hazard, the overall
health and handling characteristics of MP appear to be similar to Portland cement.
3.2 EXPERIENCE WITH HAZARDOUS AND MIXED WASTE STREAMS
Hazardous Waste
It is believed that there is no experience with this specific MP S/S system in hazardous waste
treatment, although the results obtained in this project would have direct bearing on the treatment
of non-radioactive, arsenic, chromium and lead bearing soils and sludges. However, as stated in
Section 3.1, various other phosphate-based or phosphate-containing processes have been used,
some at the full-scale, commercial level.
Radioactive Waste
This specific S/S system is not known to have been used with radioactive waste, although it is
quite possible that it has been experimented with inside the nuclear waste community. As
previously stated, other phosphate cements have been tested on surrogate radioactive waste. The
results obtained in this project would be applicable to cesium and strontium bearing radioactive
soil and sludges, as well as to those bearing heavy metals whether or not classified as mixed
waste. Because of its inorganic nature, the process would likely be resistant to biological attack
and be radiation-stable.
Mixed Waste
The work done in this published project is first independent work use of commercial magnesium
ammonium phosphate based-cement to treat surrogate mixed waste. This commercial product
appears to be the same as described by Sarkar (1990).
32
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3.3 PREPARATION OF TEST SAMPLES
Prior to performing mixture development, a number of screening tests were done to identify
reagent and water addition rates with each of the six waste types. Initial mixtures were based on
prior experience in treating similar waste. The best formulations, one for each waste type, were
then re-made, optimized, and subjected to the complete battery of test protocols. The surrogate
waste was chemically pretreated to reduce the solubility of certain metal ions; this pretreatment is
described in Section 6.1.
The magnesium phosphate based-cement tested was a product identified as Set 45 provided by
Master Builders, Inc. Mixture development was performed on the untreated samples spiked with
lead, cesium, and strontium. First, an aliquot of untreated material was placed into a blending
chamber. The specified reagent was slurried with the specified amount of tap water and added to
the untreated aliquot. The mixture was blended in a Hobart style mixture at 40 to 60 rotations
per minute (rpm) for approximately 2 to 4 minutes, or until homogenous. Once the treated
material was homogeneous, the S/S surrogate waste was compacted into 2 inch diameter by 4
inch cylindrical molds and allowed to cure in a humid environment for 10 days.
Mixture development with the untreated materials spiked with hexavalent chromium and arsenic
was performed by first pretreating the materials to reduce the valence state of the chromium ion.
Pretreatment was performed by placing an aliquot of untreated material into a blending chamber.
The specified addition rate of a 20 percent phosphoric acid solution was added to the untreated
material and blended at 40 to 60 rpm for approximately 2 to 4 minutes, or until homogeneous.
Once the mixture was homogeneous, the specified addition rate of ferrous sulfate was dissolved
in the specified addition rate of tap water and added to the mixture. The mixture was again
blended until homogeneous. The addition rates of acid and ferrous sulfate were based upon past
laboratory experience in treating similar types of materials. Cement was then added directly to
the mixture and blended until homogeneous. After the mixing was completed, the treated
material was compacted into 2 inch diameter by 4 inch cylindrical molds and allowed to cure for
10 days in a humid environment.
Table 3-1 lists the optimized formulations that were used to produce samples for the testing
program. All tests and chemical analyses were done in triplicate. Standard testing and analytical
methods for S/S waste were used, as described elsewhere in this report.
Testing results for the optimized magnesium phosphate based-cement formulations shown in
Table 3-1 are given in Table 3-2.
33
-------
Table 3-1
Magnesium Phosphate (MP) Based-Cement Formulations
("Surrogate Waste" = Media + Spike)
Media
INEEL Soil
INEEL Soil
Synthetic Soil
Synthetic Soil
Synthetic Sludge
Synthetic Sludge
Spike
As/Cr
Cs/Pb/Sr
As/Cr
Cs/Pb/Sr
As/Cr
Cs/Pb/Sr
Ingredients
H3PO4(20%)/FeSO4/MP (i)
MP(2)
H3P04(20%)/FeS04/MP (1)
MP (2)
H3PO4(20%)/FeSO4/MP (i)
MP(2)
Surrogate
Waste
Amount
(g)
7500
7500
8000
8000
8000
8000
Reagent
Addition
(%)
5/7/15
15
5/7/15
15
5/7/15
15
Water
Addition
(%)
(3)
14
22
13
15
24
13
Total
Additions
(%)
41
37
40
30
51
28
(1) Initially, the 20% phosphoric acid was added to the surrogate waste and blended in. After homogenization, the ferrous sulfate was dissolved in the water, added and blended
in. Again, after homogenization, cement was added dry to the mixture.
(2) The cement was slurried with the water prior to addition to the surrogate waste
(3) As a percent of the surrogate waste; i.e., for a 10% addition, 10 grams of reagent or water were added to 100 grams of surrogate waste
34
-------
Table 3-2
Magnesium Phosphate (MP) Based-Cement Test Results
(Data Represent The Three Samples Tested)
Test Type
t^^Mf^M^^ffijjKfljjjtjtHjMTO
As (mg/L)
UTS = 5.0
mg/L
Cr(mg/L)
UTS = 0.60
mg/L
Cs (mg/L)
Pb (mg/L)
UTS = 0.75
mg/L
Sr(mg/L)
INEEL Soil
As/Cr
Untreated
StKJa^^PffjiTOltraifttl
JBiaBSJqjSHJltHsiliB™
fffiffmpgg*fi};flffifj||))gj
81.6
74.3
84.2
230.
241.
255.
Treated
tKRJI(SSj^m^^^siB
wmfm^§P^^PSB
ffiSlffiifimfffStfftSifl
3|HBS|jgBggj|ijfflji|M
22.3
21.6
18.5
18.4
19.2
12.4
INEEL Soil
Cs/Pb/Sr
Untreated
«^&nl»liiiiii»liiiiifi
^^^^^^JM^P^
8tllK«fIiijiittliPii!t!9^
ISn*^rfijBafflnM^M^
9.
10.
12.
159.
87.
180.
31.6
33.8
31.9
Treated
3itii3Sit£8§Sll»j
ggiBBgjS«|a|g|Kj
yjjfraM^ltMefJtf
gffijgamjfgjjglm
5.5
5.3
4.4
22.1
20.5
0.52
31.7
31.8
25.9
Synthetic Soil
As/Cr
Untreated
MKJMMMIK
IUjjUHjIgjj^jgimi^flflj
^^^|^^^§
165.
185.
162.
244.
268.
247.
Treated
Iflilflliiilllllslll
jj^^^^^^^^^g
9.6
11.8
11.9
24.0
31.1
36.7
Synthetic Soil
Cs/Pb/Sr
Untreated
29.
28.
27.
443.
424.
426.
34.0
32.7
33.6
Treated
Synthetic Sludge
As/Cr
Untreated
15.5
14.9
14.6
4.5
4.4
4.3
31.0
28.9
29.1
1.54
1.90
3.85
248.
239.
312.
Treated
^gntmlj^^^^^^
23.61
23.5
21.91
28.6
28.6
29.2
Synthetic Sludge
Cs/Pb/Sr
Untreated
^^^^^^^^^ropg
58.
58.
59.
1.
3.
2.
38.0
39.4
39.9
Treated
itlf|g?a§t@liiyijii
34.8
30.6
33.4
0.11
0.039E
0.036E
25.0
22.2
23.7
35
-------
Table 3-2 (Continued)
Magnesium Phosphate (MP) Based-Cement Test Results
(Data Represent The Three Samples Tested)
Test Type
INEEL Soil
As/Cr
TTntr«>t(»H
Trp.ntf>H
INEEL Soil
Cs/Pb/Sr
TTntrMt/»H 1 TiwitcH
Synthetic Soil
As/Cr
TTntTpufoH
Tr»af(»f1
Synthetic Soil
Cs/Pb/Sr
T Tnti-MfpH
TiMtprl
Synthetic Sludge Synthetic Sludge
As/Cr Cs/Pb/Sr
T TntrMt<"H
Trt»!itFTl 1 T Tntro-itfvl
Tr<»3t»»H
ii 111 mm
As (mg/L)
UTS = 5.0
mg/L
Cr (mg/L)
UTS = 0.60
mg/L
Cs (mg/L)
Pb (mg/L)
UTS = 0.75
mg/L
Sr (mg/L)
a™™™™™
81.6
74.3
84.2
230.
241.
255.
immimmi
2.1
2.2
2.5
14.7
14.2
9.0
HMMHiMHUMIHII
9.
10.
12.
159.
87.
180.
31.6
33.8
31.9
.iittuumnmium
1.7
1.7
1.5
0.00 19E
0.0026B
0.00 19E
3.0
2.5
2.2
•••••a
165.
185.
162.
244.
268.
247.
JHgBBMtittaiHMi
2.3
2.5
2.3
27.5
23.8
19.9
ts«ffi8in»i>»»BHi
29.
28.
27.
443.
424.
426.
34.0
32.7
33.6
8.9
9.0
8.8
0.0023E
0.0020E
0.006 IE
2.5
2.6
2.6
llfflBlffllHfflM'Iffl
1.54
1.90
3.85
248.
239.
312.
minwtmnm
0.89
0.83
0.89
9.6
8.3
10.9
•Wililll
58.
58.
59.
1.
3.
2.
38.0
39.4
39.9
^Hran
36.9
37.2
38.5
5.7
6.5
7.9
18.3
19.3
20.7
36
-------
Table 3-2 (Continued)
Magnesium Phosphate (MP) Based-Cement Test Results
(Data Represent The Three Samples Tested)
Synthetic Sludge
Cs/Pb/Sr
Max. Volume
Change(%
Max. Moisture
Content (%)
37
-------
Table 3-2 (Continued)
Magnesium Phosphate (MP) Based-Cement Test Results
(Data Represent The Three Samples Tested)
Synthetic Sludge
Cs/Pb/Sr
Max. Volume
Change (%)
Max. Moisture
Content (%)
38
-------
Table 3-2 (Continued)
Magnesium Phosphate (MP) Based-Cement Test Results
(Data Represent The Three Samples Tested)
Synthetic Sludge
Cs/Pb/Sr
A Sample failed during test
B Sample failed to complete Cycle 1
D Volume change results affected by control sample shape change
E Estimated, result is below the reporting limit
I Indicates the presence of interferences in the test
UTS Universal Treatment Standards
39
-------
3.4 TESTING STAGE
The present status of testing of the MP cement-based S/S process is only at the bench scale with
surrogate mixed waste. However, scale-up to pilot and commercial scale should be
straightforward since the basic operational techniques and equipment are the same as those used
in conventional cement-based S/S processes and systems.
3.5 DEGREE OF TECHNICAL DEVELOPMENT
There is little experience with this cement-based S/S process other than that presented in Section
3.1 and that developed in this project. From a technical standpoint, existing, conventional
Portland cement-based S/S technology may not be very relevant, although pretreatment steps and
additives for the chemical immobilization of various metal species, both hazardous and
radioactive, are well established (EPA, 1996) and should be applicable since this is an aqueous
system.
3.6 DEGREE OF COMMERCIAL DEVELOPMENT
There has been no commercial development to date of this MP cement-based S/S process for
mixed waste. Again, as indicated previously, experience with conventional cement-based S/S
systems should be directly applicable.
3.7 COST CONSIDERATION
Costs for utilizing the MP cement-based S/S process for treatment of mixed waste will be higher
than those for Portland cement processes due to the considerably higher cost of the MP cement
itself. MP cement reagent costs about $760/ton ($0.38/lb) compared to about $70/ton ($0.035/lb)
for Portland cement. At the mix ratios used in this project (15 percent), the added cost of MP
cement over that of Portland cement would be about $104 per ton of waste treated, an increase
that is likely to be significant in mixed waste treatment and disposal. Other costs should be the
same as those described previously by EPA (1996) since the physical aspects of applying the
process would be about the same.
3.8 DATA GAPS
To be fair to this process, considerable additional testing would be required:
• The poor results with chromium necessitate more testing to verify that the MP cement-based
S/S process is suitable for this metal, although it is nearly certain that either size reduction of
40
-------
agglomerates, a different Cr+6 reduction approach, or longer mixing would eliminate the
problem.
Standard lead immobilization techniques, such as the use of phosphates or carbonates,
should produce low leachability in the SPLP as well as the TCLP. This should be verified.
Leachability of Cs and Sr must be reduced in this system. Chemical/physical techniques
already used in cement-based radioactive waste stabilization should be applicable here, but
this must be investigated.
It is evident from the test results for wet/dry and freeze/thaw resistance that, at the very least,
increased binder addition ratios would be required. However, it is uncertain that adequate
results can be obtained.
3.9 ASSESSMENT
Although the MP process is described as "cement-based," it is quite different chemically from
conventional Portland cement-based processes. Therefore, it cannot be assumed to give similar
results in any respect.
Specifically, the results obtained in this project with this specific MP cement-based S/S process
are:
• TCLP leachability of arsenic and lead is poor - above the latest EPA Land Disposal
Requirements (LDRs), the Universal Treatment Standards (UTS), in all cases except where
the untreated synthetic sludge had low leachability (caused by the composition of the
untreated synthetic sludge itself, as previously described).
• Chromium leachability is high - well above the UTS limits. This is due to inadequate
pretreatment to reduce Cr+6 to Cr+3, since such pretreatment is the only practical way to
insolubilize Cr in the waste form. The likely cause of the pretreatment failure is the
presence of agglomerates that did not break down during mixing and which contain Cr+6
inside that later diffuses out in the leaching test. The chromium reduction reagent - FeSO4 -
does not survive long after the cement binder is added, and so is not available to react with
Cr+6 that diffuses out of the agglomerate.
• There are no LDR standards for cesium and strontium leachability. However, they both
leach as what appears to be high levels in all cases, exhibiting no significant reduction over
the leachability of the untreated surrogate waste. This indicates that Cs and Sr are not being
speciated in a less soluble form, nor is the pH regime of the waste form favorable for their
low leachability.
41
-------
• In the SPLP leaching test, arsenic teachability is barely acceptable for the INEEL and
synthetic soils, but acceptable for the synthetic sludge. The lead leachability results are
more complicated. The very low leachability with the INEEL and synthetic soils is probably
due to the presence of phosphate and a favorable pH regime in the treated waste. The poor
synthetic sludge results are caused by an unfavorable pH regime created by the Ca(OH)2 and
the MgO in the sludge. Although the SPLP has no regulatory significance under the LDRs,
it is used as an acceptance test in some RCRA and CERCLA on-site disposal. Chromium
leachability, as in the TCLP test, is high.
• Wet/dry and freeze/thaw durability are extremely poor in every case with all samples failing
completely. This may be a consequence of the low binder addition ratio, or just a
characteristic of the MP system.
• Unconfmed compressive strengths of the MP cement-based waste forms are fairly good,
better than Portland cement would give at the low binder addition ratios used here. The
strengths achieved would be adequate for most LDR or remedial scenarios.
In summary, results with the MP cement-based S/S process were poor and the worst of the four
processes tested.
3.10 LIST OF REFERENCES
Eighmy, T.T. et al. "Heavy Metal Stabilization in Municipal Solid Waste Combustion Dry
Scrubber Residue Using Soluble Phosphate." Environ. Sci & Technol. 31 No. 11, 3330-3338.
Krueger, R.C., A.K. Chowdhury and M.A. Warner. 1991. "Full-Scale Remediation of a Grey
Iron Foundry Waste Surface Impoundment." Eniron. Prog. 10 No. 3, 206-210. August.
Master Builders Technologies. 1996. Specification Bulletin 7S10.
Sarkar,A.K. 1990. "Phosphate-Cement-Based Fast-Setting Binders." Ceram. Bull. 69, 234-
238.
Singh, D., A.S. Wagh, J.C. Cunnane and J.L. Mayberry. 1994. "Chemically Bonded Phosphate
Ceramics for Low-Level Mixed Waste Stabilization." Submitted to Proc. ASC Symposium on
Emerging Technol. in Haz. Waste Mgt., VI. Atlanta, GA, Sept. 19-21.
Wagh, A.S. and D. Singh. 1994. "Low-Temperature-Setting Phosphate Ceramics for
Stabilization of Mixed Waste." For publication in Proc. 2nd International Symp. and Exibition
on Environmental Contamination in Central and Eastern Europe, Budapest, Hungary. Work
supported by U.S. DOE, Office of Technology Development, Mixed Waste Integrated Program,
Contract W-31-109-Eng-38. September.
42
-------
4. ORTHOPHTHALIC POLYESTER (OPE) RESIN ENCAPSULATION
4.1 TECHNOLOGY DESCRIPTION
The orthophthalic polyester (OPE) resin used in this process is a commercial product. OPE is a
thermosetting polymer that requires a catalyst to initiate a reaction that hardens the resin. The
cured resin is relatively stable at high temperature and cannot be melted to a liquid like
thermoplastic polymers, such as polyethylene. This resin is used commercially in marine,
architectural applications, and for consumer products such as cultured marble. It possesses the
properties of high physical strength and very low permeability compared to more conventional
inorganic-based S/S systems. However, its application is fundamentally different than
conventional systems because the resin does not chemically react with the waste matrix or the
contaminants in it. The treatment mechanism of the OPE process is the formation of a physical
barrier between the waste contaminants and the environment in which the waste form is placed.
The ways this is accomplished are as follows: microencapsulation of the waste particles;
impregnation of the waste particles with the resin, and macroencapsulation of the impregnated,
microencapsulated particles into a high strength, nearly impermeable monolith.
This OPE resin has the following composition:
Polyester Resin 63-68%
Styrene 34.0%
The resin does not react (with exceptions discussed later) with the waste; therefore, in principle,
the OPE system should be able to isolate any contaminant, regardless of its solubility, from the
environment, provided the waste form remains intact. If the contaminants are finely dispersed,
even cracking or breaking of the waste form it will expose only small surface areas of the
contaminant to the environment, thus severely limiting contaminant leaching. Since the waste
forms are quite strong, such cracking or breaking would be minimal in any reasonable disposal
scenario.
The OPE treated waste form has no significant chemical interaction with leaching fluid such as
in the TCLP test, nor with normal real-world leaching scenarios. The waste form is hard and
durable, resistant to weathering, and extremes of temperature.
The health and handling properties of OPE resins seem to be suitable for use in S/S operations,
although the hazards are different from those of cement-based systems. They are low in acute
oral toxicity and dermal toxicity. They present potential inhalation problems from styrene
vapors and may be moderately irritating to the eye. They are classified as flammable materials,
so they must be stored and handled properly. The inhalation and flammability dangers
distinguish OPE resins from cement-based S/S processes, since the latter present particulate
inhalation and dermal irritation hazards.
43
-------
Extensive testing of a polyester emulsion encapsulation system for hazardous waste S/S (Powell
and Mahalingham, 1992) (Subramanian and Mahalingham, 1979) was done at Washington State
University (WSU). In this process, water extensible polyester resins are used to produce stable
waste-in-polyester emulsions. This was accomplished by high shear mixing of a water-based
waste liquid or sludge into the resin. In the case of waste solids, the resin is first emulsified, then
the waste is mixed in. Alternately, the solid can be dispersed directly into the resin without
water, in which case the process appears similar to the OPE process investigated in this project.
The operation can be conducted in either batch or continuous-flow mode. A considerable
number of wastes - radioactive, surrogate radioactive and hazardous - were tested: salt, metal,
and acid solutions; metal sludges; organic wastes; pesticide sludges; cyanide wastes; mixed
metal/organic sludges. Waste loadings ranged from 40 percent to 75 percent. Compressive
strengths of about 3000 psi (20.7 MPa) were obtained in the treated waste forms, and gamma
irradiation up to 500 megarads did not adversely affect the mechanical properties. Leachability,
measured by an ANS 16.1 type test was very low for a variety of metals and salts. The process
was successfully evaluated in a pilot plant with capacity for handling 15 gal./hr of liquid waste.
To achieve optimum results, it was found that the interactions among the resin, promoter,
catalyst and waste must be carefully studied and controlled. Cost of the resin used was $0.72/lb.
No resin manufacturer that could claim relevant experience in mixed waste treatment S/S
applications was found. Some manufacturers and suppliers were reluctant even to provide
samples for this application, perhaps due to fears of potential liability in the waste treatment
field, or because of bad early experiences in trying to market such processes. As a result, this
project explored new territory in S/S treatment technology, at least with respect to soil waste
treatment.
4.2 EXPERIENCE WITH HAZARDOUS AND MIXED WASTE STREAMS
Hazardous Waste
Polyester resins with styrene have been employed as a waste solidification method for over 20
years in Japan, Europe, and the United States. The process has routinely been applied to low-
level waste (LLW) streams generated by the nuclear power industry (DOE, 1999).
Radioactive Waste
The OPE S/S system has been used industrially in nuclear applications since the mid-1970s. The
results obtained in this project would be applicable to cesium and strontium bearing radioactive
soil and sludges.
44
-------
Mixed Waste
The work done in this project is believed to be the first independent, published work on using
orthophthalic polyester encapsulation to treat different surrogate mixed wastes containing various
soil types.
4.3 PREPARATION OF TEST SAMPLES
Prior to performing mixture development, a number of screening tests were done to identify
reagent and water addition rates with each of the six waste types. Initial mixtures were based on
prior experience in treating similar waste. The best formulations, one for each waste type, were
then re-made and subjected to the complete battery of test protocols. Two pretreatment steps
were developed and used as described in Section 6.2.
The orthophthalic polyester resin used for this project was Ashland MR 11109 Unsaturated
Polyester Resin. The OPE resin used for the resin impregnation treatment step was blended with
additional styrene monomer at a ratio of 1:1 to reduce its viscosity and enhance its impregnation
characteristics.
The untreated samples were reduced in size by crushing to pass a Number 6 mesh screen (-1/8").
The screened waste was weighed and then placed in a Hobart type laboratory mixer to provide
thorough mixing. The treatment reagents were added to the sample to chemically pretreat the
waste to the extent of the solubility of the contaminants for approximately 5 minutes. The
pretreated waste was weighed and un-catalyzed resin was added for a resin soak cycle. The
pretreated and impregnated waste was again placed into a Hobart type laboratory mixer. While
the mixer was running, catalyst was added to the resin impregnated pretreated waste to ensure
proper dispersion. While the mixer continued to run, additional catalyst resin was finally added
to the pretreated and impregnated waste to fill the voids between the impregnated waste particles
and to encapsulate the impregnated waste particles. After mixing for a minimum of 5 minutes,
the S/S surrogate waste was filled into 2 inch diameter by 4 inch high cylindrical molds and
allowed to cure at room temperature environment for a minimum of 4 days. The samples began
to show significant set in 15 - 30 minutes after catalyst addition.
Table 4-1 lists the formulations that were used to produce samples for the testing program. All
tests and chemical analyses were done in triplicate. Standard testing and analytical methods for
S/S waste were used, as described elsewhere in this report.
The results of testing of the samples produced as shown in Table 4-1 are given in Table 4-2:
45
-------
Table 4-1
Orthophthalic Polyester (OPE) Resin Encapsulation Formulations
("Surrogate Waste" = Media + Spike)
Media
INEEL
Soil
INEEL
Soil
Synthetic
Soil
Synthetic
Soil
Synthetic
Sludge
Synthetic
Sludge
Spike
As/Cr
Cs/Pb/Sr
As/Cr
Cs/Pb/Sr
As/Cr
Cs/Pb/Sr
Pretreatment Reagent Additions (%)*
H3PO<
6.0
6.0
6.0
FeSO4
48.5
48.5
48.5
MgO
16.4
3.15
16.4
3.15
16.4
3.15
Ca(OH)2
16.4
16.4
16.4
Cement
5.7
5.7
5.7
Water
28.6
15.0
28.6
10.0
28.6
20.0
Sub-total
Addn.
115.6
25.2
115.6
19.2
115.6
29.2
Resin Impregnation (Soak) Additions
(%)*
OPE
42.1
13.6
37.4
13.6
42.1
17.7
SM**
42.1
13.6
37.4
13.6
42.1
17.7
Catalyst***
0.84
0.27
0.75
0.27
0.84
0.35
Sub-total
Addn.
85.0
27.6
75.6
27.6
85.0
35.8
Resin Encapsulation Additions (%)*
OPE
27.2
13.7
26.3
13.7
27.2
14.5
SM
27.2
13.7
26.3
13.7
27.2
14.5
Catalyst
0.54
0.27
0.53
0.27
0.54
0.27
Sub-total
Addn.
55.0
27.6
53.1
27.6
55.0
29.3
Total
Reagent
Addition
(%)*
255.6
80.4
244.3
80.4
255.6
94.3
* As a percent of the surrogate waste; i.e., for a 10% addition, 10 grams of reagent or water were added to 100 grains of surrogate waste
** Styrene monomer
*** The catalyst used was a peroxide, in this case, methyl ethyl ketone peroxide
46
-------
Table 4-2
Orthophthalic Polyester (OPE) Resin Encapsulation Test Results
(Data Represent The Three Samples Tested)
Test Type
Untreated Treated Untreated
As (mg/L)
UTS = 5.0
mg/L
INEEL Soil
As/Cr
INEEL Soil
Cs/Pb/Sr
Synthetic Soil
As/Cr
Synthetic Soil
Cs/Pb/Sr
Synthetic Sludge
As/Cr
Synthetic Sludge
Cs/Pb/Sr
Cr (mg/L)
UTS = 0.60
mg/L
230.
241.
255.
0.0080E
0.0039E
0.0049E
244.
268.
247.
0.0069E
ND
ND
248.
239.
312.
ND
ND
0.0060E
Cs (mg/L)
10.
12.
1.8
2.0
1.4
29.
28.
27.
4.4
4.0
0.37
58.
58.
59.
3.4
3.9
3.9
Pb (mg/L)
UTS = 0.75
mg/L
Sr(mg/L)
159.
87.
180.
31.6
33.8
31.9
0.23
0.14
0.52
5.1
5.9
3.5
443.
424.
426.
34.0
32.7
33.6
0.36
0.40
0.37
3.6
3.3
3.4
1.
3.
2.
38.0
39.4
39.9
0.69
0.45
0.65
1.9
2.0
2.0
47
-------
Table 4-2 (Continued)
Orthophthalic Polyester (OPE) Resin Encapsulation Test Results
(Data Represent The Three Samples Tested)
Test Type
BBBSSBfflffiffnB'ilfflnffilftffi^
haMjaatr^fflM-rgERMBSi
tfM^BjHlEPS?lffHmlTM»Bil(BM
•BMCTgaBgflfCTiifiiytBffHBfflBi
ffigjjgBg^^aH^BK^fnjgffllrnH
As (mg/L)
UTS =5.0
mg/L
Cr (mg/L)
UTS = 0.60
mg/L
Cs (mg/L)
Pb (mg/L)
UTS = 0.75
mg/L
Sr (mg/L)
INEEL Soil
As/Cr
Untreated
M&PPI
5ffBmHH|ffiSBBtflBlffli3
niTMiiliir Til nHrBniTii
ifttJinHnTffiinnBnRnlTrmi
ggjgggmjflgmjjgjfljgjg
81.6
74.3
84.2
230.
241.
255.
Treated
mmm^
0.065E
0.078E
0.061E
0.95
1.1
1.0
INEEL Soil
Cs/Pb/Sr
Untreated
9.
10.
12.
159.
87.
180.
31.6
33.8
31.9
Treated
jyffilillljl
1.7
1.7
1.5
ND
0.0028E
ND
1.3
1.4
1.3
Synthetic Soil
As/Cr
Untreated
165.
185.
162.
244.
268.
247.
, Treated
j5jjj8|f§J8S185^
0.0 15E
0.0 16E
0.0 12E
0.014
0.036
0.023
Synthetic Soil
Cs/Pb/Sr
Untreated '
|ff}{jjjjgjj|iifS|Pfj|j*ff?njii
ttssBSllii$$isntisJK£%$siSK
ZJKJiaimlmffivSmm
— — — —M™
29.
28.
27.
443.
424.
426.
34.0
32.7
33.6
, Treated
5.4
6.9
6.6
ND
0.0057E
0.0078E
0.78
0.37
0.53
Synthetic Sludge
As/Cr
Untreated
ili^— — ^-——i
jHHyUn)flffjfffl|ifliji|[j
"™SSB^^^HHi!H'ffll
1.54
1.90
3.85
248.
239.
312.
Treated
0.0 17E
0.0 15E
0.0 14E
0.10
0.11
0.13
Synthetic Sludge
Cs/Pb/Sr
Untreated !
•t8taMBaaiiii»aii»
SllEEjfflllflUi i Illlllilliuffill
^Wg!ffllff(nn|n™^8^^|
SaBliBMttBalHtmiihStll
nrrmii-..irTmmrnn
58.
58.
59.
1.
3.
2.
38.0
39.4
39.9
Treated
7.5
8.2
7.8
0.0013E
0.0030E
0.019E
0.78
0.87
.083
48
-------
Table 4-2 (Continued)
Orthophthalic Polyester (OPE) Resin Encapsulation Test Results
(Data Represent The Three Samples Tested)
Test Type
INEEL Soil
As/Cr
Untreated
Treated
INEEL Soil
Cs/Pb/Sr
Untreated Treated
Synthetic Soil
As/Cr
Untreated | Treated
Synthetic Soil
Cs/Pb/Sr
Untreated | Treated
Synthetic Sludge
As/Cr
Untreated Treated
Synthetic Sludge
Cs/Pb/Sr
Untreated
Treated
Max. Volume
Change (%)
Max. Moisture
Content f %
49
-------
Table 4-2 (Continued)
Orthophthalic Polyester (OPE) Resin Encapsulation Test Results
(Data Represent The Three Samples Tested)
Synthetic Sludge
Synthetic Sludge
Synthetic Soil
Cs/Pb/Sr
Synthetic Soil
As/Cr
INEEL Soil
Cs/Pb/Sr
INEEL Soil
As/Cr
Untreated Treated
Untreated Treated
Untreated Treated Untreated Treated
Untreated Treated
Untreated Treated
Max. Volume
Change(%)
Max. Moisture
Content (%)
50
-------
Table 4-2 (Continued)
Orthophthalic Polyester (OPE) Resin Encapsulation Test Results
(Data Represent The Three Samples Tested)
Test Type
===___— _^^
BfffjBBiMMBllUiJfjll^lffiliB
fe'&ttfiaiiiEaigiiiB
Stress at
Failure (psi)
Strain at
Failure (%)
INEEL Soil
As/Cr
Untreated
^__— _____•
i&fj^[3l|£|fi;isjy|j
24.6
1.83
Treated
- - . .
|B^!fll|BiMHjiB
lifiliiililfiiili
JHHHmBnBtt^^^S
BeHpaiBpatpNSmfi
UfifigKa&tJfisg&gJgJS
5197.1
4957.2
5626.5
7.2
6.5
7.5
INEEL Soil
Cs/Pb/Sr
Untreated Treated
========i=======
fsgBjg^BaaaairegM aMOTHBrnHmaa
lgi?B*iigaK*fHa!OfiESTJg
iMiliasmHis^ia^reiSi
^^^^^n^^^^^^^
31.7
2.04
BJffr5JIJJr''sB^KBw
SJBBfSf^tilntWTwffi
ilsiliM^lisil
SmJCTHOTtiTOHlwS
3443.7
3517.3
3694.3
5.5
4.7
4.1
Synthetic Soil
As/Cr
Untreated | Treated
SBSHi^ifS^lBl^lilSSHall^Sli
Synthetic Soil
Cs/Pb/Sr
Untreated | Treated
BHnEBi!KiKa^8SH»£»
14.4 3257.0
3502.3
4226.1
2.38 6.0
4.5
5.0
SJijjjasiii^-s^saa
-------
4.4 TESTING STAGE
The present status of testing of the OPE resin encapsulation S/S process is only at the bench scale
with surrogate mixed waste. Scale-up to at least the pilot stage should be predicated on the
previous work with a similar system (Powell and Mahalingham, 1992) (Subramanian and
Mahalingham, 1979).
4.5 DEGREE OF TECHNICAL DEVELOPMENT
There is little experience with this specific OPE resin encapsulation S/S process other than that
presented in this report and DOE (1999). However, previous work with a similar system (Powell
and Mahalingham, 1992) (Subramanian and Mahalingham, 1979) should prove applicable.
Pretreatment steps and additives for the chemical immobilization of various metal species, both
hazardous and radioactive, are well established in the literature and in current commercial
methods.
4.6 DEGREE OF COMMERCIAL DEVELOPMENT
OPE S/S system has been used industrially in nuclear applications since the mid-1970s.
Although this project and DOE (1999) provide more information about the process, a full
commercial scale-up effort is needed to explore essentially new territory.
4.7 COST CONSIDERATION
There are situations where cement-based processes cannot be used; e.g., where it is necessary to
immobilize salts such as nitrates. Also, where very high strength and durability are required, the
OPE resin encapsulation S/S process may be competitive. It has been documented that the cost
estimates for treating waste volumes over 30 cubic meters indicate that the high loadings
achievable with polyester, the process more than recovers the higher initial material and
development costs. The assumption that labor and capital costs for the two processes are the
same is based on process equipment similarities. Therefore, the cost benefit of OPE over that of
Portland cement is based exclusively on material cost and disposal costs (DOE, 1999).
4.8 DATA GAPS
One area of OPE treatment methodology that was not explored in this project was that of a
greater degree of size reduction in the waste. It is feasible, although perhaps expensive, to reduce
the waste particle size to somewhere near -100 mesh. Conceivably, this could eliminate both the
chemical pretreatment and infiltration steps, greatly reducing the reagent requirements, especially
52
-------
that of the expensive resins, and the volume increase associated with the present process. It
would also eliminate two operational steps.
The resin used in this project was selected for its physical properties in normal industrial use.
Since it was not specifically designed for S/S work, and given the wealth of resin technology
available in the marketplace, it seems likely that a resin/catalyst package specifically designed
for this application could be even more effective, especially in regard to cost. It seems especially
important to eliminate any possible foaming problem encountered in this process. The properties
of waste forms produced by OPE, especially durability and strength properties, are dependent on
the integrity of the monolith. While this phenomenon did not appear to cause any real
difficulties in the bench-scale tests, foaming will be exacerbated as the process scale increases.
It is recommended that one or more of the waste types used in this study be selected for
additional treatability work using a treatment methodology based on finely crushing the
untreated sample prior to resin addition. Even though fine crushing is an additional processing
step, it may result in simplifying the overall resin treatment process and significantly reducing
the total reagent addition required for adequate treatment. For many soil type waste and lumpy
sludges where it is not desired to reduce the grain size to a -200 mesh, a combination of aqueous
based-and resin based treatment processes may work best with highly hazardous waste. For an
aqueous based treatment process, which renders many of the contaminants insoluble, followed by
drying, crushing, and resin-based treatment to encapsulate the insolubilized waste particles and
the soluble chloride and nitrate components, may result in the most effective method.
It seems likely that further optimization of this process has the potential for reducing resin
addition ratios, independently of the above mentioned possible improvements to be gained from
further work with this system.
4.9 ASSESSMENT
Specifically, the results obtained with the OPE resin encapsulation S/S process are as follow:
• TCLP results are uniformly excellent for arsenic and chromium, but lead leachability ranges
from marginal to unacceptable. Obviously, the pretreatment for lead with phosphoric acid
and MgO was only partially successful.
• Cesium and strontium leachability in the TCLP test was reduced by factors of 5 to 10 or
more. Whether this is sufficient is uncertain, since there are no LDR standards for these
contaminants.
« In the SPLP, teachabilities of arsenic, chromium, and lead are all good to excellent with the
exception of unacceptable results for Cr in the INEEL soil. The latter failure is likely due to
un-reduced Cr+6 in this surrogate waste.
53
-------
• Durability of all samples tested was excellent in the wet/dry and freeze/thaw tests. This was
expected in this nearly impermeable S/S system, which distinguishes it from most cement-
based systems.
• Unconfmed compressive strengths for all samples tested were extremely high, in the 5000
psi to more than 7000 psi range. These strengths are virtually unattainable in any cement-
based system in any practical way. Furthermore, the strain-at-failure values for these
samples indicate good ductility compared to cement-based waste forms; this result should
provide good tensile and flexural strength, meaning that these waste forms should be
difficult to fracture.
• Although the surrogate waste was assumed to be chemically inert with reference to the resin
setting technology, it was found that this was not completely so. Contaminants in the waste
had an impact on the rate of the polymerization reactions that cause the resin to set and
solidify, however, not to a serious degree enough to require change in the catalyst addition
rate. These interactions were more pronounced in the surrogate waste containing cesium,
lead, and strontium, although the specific contaminant(s) was/were not identified, and could
be the nitrate ion instead of, or in addition to, the metal(s). Cesium is known to have
catalytic properties relative to the decomposition of peroxides. Some foaming and volume
expansion were also encountered. Apparently, the peroxide catalyst reacted with
contaminants in the wastes, releasing oxygen that caused foaming. Foaming could be a
problem in large scale operations, causing porosity in the waste form due to entrapped gas.
In summary, results with the OPE resin encapsulation S/S process were very good, with the only
negatives being due to pretreatment failures which should be easy to correct. Unfractured resin
treated samples do not appear to release any contaminants into the environment. They are dust
free and can be readily handled. Unfractured samples should perform very well in either the
TCLP and SPLP test methodologies (if the sample preparation procedure allowed monolith
testing) or in the ANS 16.1 test procedure under NRC requirements. Durability and strength
properties for waste forms produced with the OPE process were uniformly excellent.
Since the OPE resin system does not rely on reaction with contaminants in the waste, it is an
ideal treatment process for use with high concentrations of water soluble contaminants - nitrate
or chloride salts - that cannot be immobilized in conventional S/S processes, as well as lower
concentrations of toxic or radioactive metals that are difficult to stabilize chemically. Such waste
streams would include evaporator residues, such as salt cake, and incineration residues, as well as
dry or nearly dry salt-containing sludges. The salt cake should be crushed to near -100 or -200
mesh particle size prior to encapsulation in resin.
54
-------
4.10 LIST OF REFERENCES
Powell, M.R. and R. Mahalingham. 1992. "Continuous Solidification/Stabilization Processing
of Hazardous Waste Through Polymeric Microencapsulation." J. Ind. Eng. Chem. Res. V. 31.
Subramanian, R.V. and R. Mahalingham. 1979. "Immobilization of Hazardous Residues by
Polyester Encapsulation." Toxic and Hazardous Waste Disposal, R.B. Pojasek, ed., Chap. 14.
Ann Arbor Science Pub.. Ann Arbor, MI.
U.S. DOE. 1999. Mixed Waste Encapsulation in Polyester Resins. DOE/EM-0480. Office of
Environment Management, Richland, Washington. September.
55
-------
56
-------
5. EPOXY VINYL ESTER (EVE) RESIN ENCAPSULATION
5.1 TECHNOLOGY DESCRIPTION
The Epoxy Vinyl Ester (EVE) resin used in this process is a commercial product. EVE is
described as a thermosetting polymer that requires a catalyst to initiate the reaction that hardens
the resin. The cured resin is relatively stable at high temperature and cannot be melted to a liquid
like thermoplastic polymers such as polyethylene. EVE resins (Dow Plastics, 1996) are strong,
tough and resistant to acids, alkalies, and solvents. This resin possesses the properties of high
physical strength and very low permeability compared to more conventional inorganic-based S/S
systems. EVE resins are less polar than polyester resins, making them less susceptible to the
effects of water. Because of the molecular chain structure, EVE resin castings absorb mechanical
and thermal shocks.
This EVE resin has the following composition:
Styrene monomer 40-60%
Treated amorphous s ilica 1 -3 %
Vinyl ester resin Balance
Typical compressive strength for castings made with this type of resin are in the range of 16,000
to 17,000 psi (110-117 MPA), with tensile strengths of 11,000 to 12,000 psi (76 - 83 MPa).
While waste forms made with the resin would likely exhibit considerably less strength, these
levels are expected to be much higher than those obtainable with cement-based, inorganic S/S
systems, especially with regard to tensile strength. The strength of cured EVE resins is still at
least half of the room temperature value at 225°F (107°C).
The health and handling properties of EVE resins seem to be suitable for use in S/S operations,
although the hazards are different from those of cement-based systems. They are low in acute
oral toxicity and dermal toxicity. They present potential inhalation problems from styrene
vapors and may be moderately irritating to the eye. They are classified as flammable materials,
so they must be stored and handled properly. The inhalation and flammability dangers
distinguish EVE resins from cement-based S/S processes, since the latter presents particulate
inhalation and dermal irritation hazards.
Application of this system to S/S treatment is fundamentally different than for conventional
cement-based systems, because the resin does not chemically react with the waste matrix or the
contaminants in it. The treatment mechanism of the EVE process is the formation of a physical
barrier between the waste contaminants and the environment in which the waste form is placed.
This barrier is provided in several ways as follows: microencapsulation of the waste particles;
impregnation of the waste particles with the resin, and macroencapsulation of the impregnated,
microencapsuiated particles into a high strength, nearly impermeable monolith.
57
-------
Because the resin does not react (with exceptions discussed later) with the waste, it is not
contaminant concentration sensitive in the way that conventional processes are. Therefore, in
principle, the EVE system should be able to isolate any contaminant, regardless of its solubility,
from the environment, provided the waste form remains intact. If the contaminants are finely
dispersed, even cracking or breaking of the waste form will expose only small surface areas of
the contaminant to the environment, thus severely limiting contaminant leaching. Since the
waste forms are quite strong, such cracking or breaking would be minimal in any reasonable
disposal scenario.
The EVE treated waste form has no significant chemical interaction with leaching fluid, such as
in the TCLP test, nor with normal real-world leaching scenarios. The waste form is hard and
durable, resistant to weathering and extremes of temperature.
In the 1970s, an organic polymer S/S process for radioactive waste was developed, piloted,
submitted for approval by the Nuclear Regulatory Commission (NRC), and used in
demonstration tests at several nuclear plants (Filter, 1980). A very complete set of tests was run
on this system using both surrogate and real low-level waste. Real radioactive waste tested
included PWR and BWR evaporator waste at 12 percent solids, sludge containing waste water
and filter aid, ion exchange resins, and spent decontamination solutions. The waste form was
found to be unaffected by radiation doses of 20 megarads, had excellent freeze/thaw, water
immersion, thermal cycling and short-term high temperature resistance, high strength, and low
leachability of cesium and cobalt. This process has been described as vinyl ester encapsulation
(Conner, 1990), and given the nature of the waste treated, may have been a waste-in-resin
emulsion. It is not known if the resin is similar to the EVE resin evaluated in this project. Other
development work using epoxy resin systems was recently done at INEL (Tyson and
Schwendiman, 1995).
No current resin manufacturer was found that claimed relevant experience in mixed waste S/S
treatment. Some manufacturers and suppliers were reluctant even to provide samples for this
application, perhaps due to fears of potential liabilities in the waste treatment field, or because of
bad experiences in trying to market such processes in the early days of radioactive waste. As a
result, this project explored new territory in S/S treatment technology, at least in respect to soil
waste treatment.
5.2 EXPERIENCE WITH HAZARDOUS AND MIXED WASTE STREAMS
Hazardous Waste
It is believed that there is no experience with this specific EVE S/S system in hazardous waste
treatment, although the results obtained in this project would have direct bearing on the treatment
of non-radioactive, arsenic, chromium, and lead bearing soils and sludges.
58
-------
Radioactive Waste
No EVE S/S system is known to have been used with radioactive wastes. However, the results
obtained in this project would be applicable to cesium and strontium bearing radioactive soil and
sludges.
Mixed Waste
The work done in this project is believed to be the first independent, published work on using
epoxy vinyl ester encapsulation to treat surrogate mixed waste.
5.3 PREPARATION OF TEST SAMPLES
Prior to performing mixture development, a number of screening tests were done to identify
reagent and water addition rates with each of the six waste types. Initial mixtures were based on
prior experience in treating similar waste. The best formulations, one for each waste type, were
then re-made, optimized, and subjected to the complete battery of test protocols. Two
pretreatment steps were developed and used as described in Section 6.2.
The Epoxy Vinyl Ester resin used for this project was Dow DERAKANE 411-700PAT. The
untreated samples were reduced in size by crushing to pass a Number 6 mesh screen (-1/8"). The
screened waste was weighed and then placed in a Hobart type laboratory mixer to simulate high
shear mixing. The treatment reagents were added to the sample to chemically pretreat the waste
to the extent of the solubility of the contaminants for approximately 5 minutes. The pretreated
waste was weighed and un-catalyzed resin was added for a resin soak cycle. The pretreated and
impregnated waste was again placed into a Hobart type laboratory mixer. While the mixer was
running, catalyst was then added to the resin impregnated pretreated waste to ensure its
hardening. While the mixer continued to run, additional catalyst resin was finally added to the
pretreated and impregnated waste to fill the voids between the impregnated waste particles and to
encapsulate the impregnated waste particles. After mixing for a minimum of 5 minutes, the S/S
surrogate waste was compacted into 2 inch diameter by 4 inch cylindrical molds and allowed to
cure at room temperature environment for a minimum of 4 days. The samples began to show
significant set in 15-30 minutes after catalyst addition.
Table 5-1 lists the optimized formulations that were used to produce samples for the testing
program. All tests and chemical analyses were done in triplicate. Standard testing and analytical
methods for S/S waste were used, as described elsewhere in this report.
The results of testing of the samples produced as shown in Table 5-1 are given in Table 5-2:
59
-------
Table 5-1
Epoxy Vinyl Ester (EVE) Resin Encapsulation Formulations
("Surrogate Waste" = Media + Spike)
Media
INEEL
Soil
INEEL
Soil
Synthetic
Soil
Synthetic
Soil
Synthetic
Sludge
Synthetic
Sludge
Spike
As/Cr
Cs/Pb/Sr
As/Cr
Cs/Pb/Sr
As/Cr
Cs/Pb/Sr
Pretreatment Reagent Additions (%)*
6.0
6.0
6.0
FeSO4
48.5
48.5
48.5
MgO
16.4
3.15
16.4
3.15
16.4
3.15
Ca(OH)2
16.4
16.4
16.4
Cement
5.7
5.7
5.7
Water
28.6
15.0
28.6
10.0
28.6
20.0
Sub-total
Addn.
115.6
25.2
115.6
19.2
115.6
29.2
Resin Impregnation (Soak) Additions
(%)*
EVE
84.2
84.2
38.2
Catalyst*"
1.68
0.65
1.50
0.65
1.68
0.76
Sub-total
Addn.
85.9
33.4
76.3
33.4
85.9
39.0
Resin Encapsulation Additions (%)*
EVE SM Catalyst
1.09
0.57
1.09
0.57
1.09
0.59
Sub-total
Addn.
55.7
29.1
53.7
29.1
55.7
30.2
Total
Reagent
Addition
(%)*
257.2
87.7
245.6
81.8
257.2
98.4
* As apercent of the surrogate waste, i.e., for a 10% addition, 10 grams of reagent or water were added to 100 grams of surrogate waste
** Styrene monomer
*** The catalyst used was a peroxide, in this case, methyl ethyl ketone peroxide
60
-------
Table 5-2
Epoxy Vinyl Ester (EVE) Resin Encapsulation Test Results
(Data Represent The Three Samples Tested)
Test Type
^^SEj^jSs&^^g^K^^^^^
^•fjP^BWCTCTiSryln^llwfSra
Sa^^gHBB'gj^jgKBS^^^t^
^^mTOt^^S^^^^^^^fflKraCT
As (mg/L)
UTS = 5.0
mg/L
Cr(mg/L)
UTS = 0.60
mg/L
Cs (mg/L)
Pb (mg/L)
UTS = 0.75
mg/L
Sr(mg/L)
INEEL Soil
As/Cr
Untreated
81.6
74.3
84.2
230.
241.
255.
Treated
0.038E I
0.092E
0.015E
0.15
0.27
ND
INEEL Soil
Cs/Pb/Sr
Untreated
9.
10.
12.
159.
87.
180.
31.6
33.8
31.9
Treated
2.5
2.4
2.4
0.0039E
0.0049E
0.0072E
5.3
5.1
5.3
Synthetic Soil
As/Cr
Untreated
j
165.
185.
162.
244.
268.
247.
Treated
0.0098E
0.0058E
ND
0.054
0.044
ND
Synthetic Soil
Cs/Pb/Sr
Untreated
29.
28.
27.
443.
424.
426.
34.0
32.7
33.6
Treated
6.3
6.0
6.2
0.00044
E
ND
0.00039
E
4.4
3.9
4.0
Synthetic Sludge
As/Cr
Untreated
1.54
1.90
3.85
248.
239.
312.
Treated
ND
0.054E
0.035E
0.19
0.076
0.062
Synthetic Sludge
Cs/Pb/Sr
Untreated
58.
58.
59.
1.
3.
2.
38.0
39.4
39.9
Treated
4.1
4.3
3.8
0.21
0.33
0.36
2.4
2.4
2.2
61
-------
Table 5-2 (Continued)
Epoxy Vinyl Ester (EVE) Resin Encapsulation Test Results
(Data Represent The Three Samples Tested)
Test Type
INEEL Soil
As/Cr
INEEL Soil
Cs/Pb/Sr
Synthetic Soil
As/Cr
Synthetic Soil
Cs/Pb/Sr
Synthetic Sludge
As/Cr
Synthetic Sludge
Cs/Pb/Sr
As (mg/L)
UTS = 5.0
mg/L
Cr(mg/L)
UTS = 0.60
mg/L
Cs (mg/L)
Pb (mg/L)
UTS = 0.75
mg/L
Sr(mg/L)
81.6
74.3
84.2
230.
241.
255.
0.01 IE
0.023E
0.020E
0.44
0.50
0.12
9.
10.
12.
159.
87.
180.
31.6
33.8
31.9
1.9
1.3
1.7
0.0034E
0.030E
0.00090
E
2.4
1.8
2.4
165.
185.
162.
244.
268.
247.
ND
ND
ND
0.014
0.009 IE
ND
29.
28.
27.
443.
424.
426.
34.0
32.7
33.6
4.4
4.4
4.6
0.0040E
0.00029
E
0.0052E
1.5
1.5
1.6
1.54
1.90
3.85
248.
239.
312.
ND
ND
ND
0.024
0.0082E
0.013
58.
58.
59.
1.
3.
2.
38.0
39.4
39.9
7.9
6.9
7.8
0.0090E
0.0079E
0.0095E
1.2
0.99
1.1
62
-------
Table 5-2 (Continued)
Epoxy Vinyl Ester (EVE) Resin Encapsulation Test Results
(Data Represent The Three Samples Tested)
Test Type
INEEL Soil
As/Cr
INEEL Soil
Cs/Pb/Sr
Synthetic Soil
As/Cr
Synthetic Soil
Cs/Pb/Sr
Synthetic Sludge
As/Cr
Synthetic Sludge
Cs/Pb/Sr
Max. Volume
Change (%)
Max. Moisture
Content (%)
63
-------
Table 5-2 (Continued)
Epoxy Vinyl Ester (EVE) Resin Encapsulation Test Results
(Data Represent The Three Samples Tested)
Test Type
INEEL Soil
As/Cr
Untreated | Treated
INEEL Soil
Cs/Pb/Sr
Untreated Treated
Synthetic Soil
As/Cr
Untreated
Treated
Synthetic Soil
Cs/Pb/Sr
Untreated
Treated
Synthetic Sludge
As/Cr
Untreated
Treated
Synthetic Sludge
Cs/Pb/Sr
Untreated
Treated
Max. Volume
Change (%)
Max. Moisture
Content (%)
64
-------
Table 5-2 (Continued)
Epoxy Vinyl Ester (EVE) Resin Encapsulation Test Results
(Data Represent The Three Samples Tested)
Test Type
INEEL Soil
As/Cr
INEEL Soil
Cs/Pb/Sr
Synthetic Soil
As/Cr
Synthetic Soil
Cs/Pb/Sr
Synthetic Sludge
As/Cr
Untreated [ Treated
Synthetic Sludge
Cs/Pb/Sr
Untreated
Treated
Treated I Untreated I Treated
A Sample failed during test
B Sample failed to complete Cycle 1
C Sample loss results were negative
D Volume change results affected by control sample shape change
E Estimated, result is below the reporting limit
I Indicates the presence of interferences in the test
ND Not detected
• No sample or data available
UTS Universal Treatment Standards
65
-------
5.4 TESTING STAGE
The present status of testing of the EVE resin encapsulation S/S process is only at the bench
scale with surrogate mixed waste. Scale-up to at least the pilot stage should be predicated on the
previous work with a similar system (Dow Plastics, 1996) (Filter, 1980) (Tyson and
Schwendiman, 1995).
5.5 DEGREE OF TECHNICAL DEVELOPMENT
There is little experience with this specific EVE resin encapsulation S/S process other than that
presented in this report. However, the previous work with a similar system (Dow Plastics, 1996)
(Filter, 1980) (Tyson and Schwendiman, 1995) should prove applicable. Pretreatment steps and
additives for the chemical immobilization of various metal species, both hazardous and
radioactive, are well established in the literature and in current commercial methods.
Processing/operational steps for this system are not well established.
5.6 DEGREE OF COMMERCIAL DEVELOPMENT
There has been no commercial development of this process to date. Full commercial scale-up
will be exploring essentially new territory and will require considerable effort.
5.7 COST CONSIDERATION
The EVE resin current price is about $ 1.65/pound for in truckload quantities, FOB. The
processing/operational costs are also likely to be higher than those of cement-based systems.
Costs due to reagent additions (including water) are very high compared to either cement-based
or polyethylene encapsulation systems. Ignoring the pretreatment reagent additions, which
would likely be about the same for all systems tested, reagent additions ranged from 55 percent
to 140 percent, depending on the surrogate waste, compared to typically 50 percent for
polyethylene encapsulation and 25 percent to 50 percent for the cement-based processes. The
volume increase of any S/S process is especially important for mixed waste, because of their very
high transportation and disposal costs compared to those for hazardous waste. However, there
are situations where cement-based processes cannot be used; e.g., where it is necessary to
immobilize salts such as nitrates. Also, where high strength and durability are required, the EVE
resin encapsulation S/S process may be competitive. Finally, it seems likely that optimization of
this process has the potential to reduce resin addition ratios.
66
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5.8 DATA GAPS
One area of EVE treatment methodology that was not explored in this project was that of a
greater degree of size reduction in the waste. It is feasible, although perhaps expensive, to reduce
the waste particle size to somewhere near -100 mesh. Conceivably, this could eliminate both the
chemical pretreatment and infiltration steps, greatly reducing the reagent requirements, especially
that of the expensive resins, and the volume increase associated with the present process. It
would also eliminate two operational steps.
The resin used in this project was selected for its physical properties in normal industrial use.
Since it was not specifically designed for S/S work, and given the wealth of resin technology
available in the marketplace, it seems likely that a resin/catalyst package specifically designed
for this application could be even more effective, especially as regards cost. It seems especially
important to eliminate the foaming problem encountered in this process. Because the properties
of waste forms produced by EVE, especially durability and strength properties, are dependent on
the integrity of the monolith, foaming will be exacerbated as the process scale increases.
It is recommended that one or more of the waste types used in this study be selected for
additional treatability work using a treatment methodology based on finely crushing the
untreated sample prior to resin addition. Even though fine crushing is an additional processing
step, it may result in simplifying the overall resin treatment process and significantly reducing
the total reagent addition required for adequate treatment. For many soil type waste and lumpy
sludges where it is not desired to reduce the grain size to a -200 mesh, a combination of aqueous-
based and resin-based treatment processes may work best for highly hazardous waste. An
aqueous-based treatment process, which renders many of the contaminants insoluble, followed
by drying and crushing and then followed by a resin-based treatment process to encapsulate the
insolubilized waste particles and the soluble chloride and nitrate components may result in the
most effective treatment possible.
It seems likely that further optimization of this process has the potential for reducing resin
addition ratios, independently of the above mentioned possible improvements to be gained from
further work with this system.
5.9 ASSESSMENT
Specifically, the results obtained in this project with this specific EVE resin encapsulation S/S
process are:
• TCLP results are uniformly excellent for arsenic, good to excellent for chromium, and
acceptable to excellent for lead.
67
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• Cesium and strontium teachability in the TCLP test was reduced by factors of about 4 to 15
or more. Whether this is sufficient is uncertain, since there are no LDR standards for these
contaminants.
• In the SPLP, leachabilities of arsenic, chromium, and lead are all excellent with the
exception of marginal results for Cr in the INEEL soil. The latter failure is likely due to un-
reduced Cr+6 in this surrogate waste.
• Durability in the wet/dry test was excellent for all the As/Cr contaminated surrogate waste
and the synthetic sludge Cs/Pb/Sr contaminated waste, but marginal to unacceptable for the
others. The marginal and unacceptable samples were those with the lowest resin addition
ratios, both in the resin soak and resin encapsulation steps. These results indicate that, not
surprisingly, the impermeability of waste forms produced with the EVE process is dependent
on sufficient resin addition. Durability in the freeze/thaw test was excellent for all except
the synthetic soil, Cs/Pb/Sr contaminated samples, which had relatively low resin addition
ratios and exhibited marginal resistance.
• Unconfined compressive strengths ranged from acceptable to high, 50 psi to more than 2100
psi. The strength variation did not correlate with resin addition ratios, but appeared to be
affected most strongly by the surrogate waste treated. These strengths ranged from easily
attainable cement-based system levels to well above practical levels for cement-based
processes. All strain-at-failure values for these samples indicate good ductility compared to
cement-based waste forms.
• Although the surrogate waste was assumed to be chemically inert with reference to the resin
setting technology, it was found that was not completely so. Contaminants in the waste had
an impact on the rate of the polymerization reactions that cause the resin to set and solidify,
although not to a serious degree, so no changes in the recommended catalyst addition rate
was required. These interactions were more pronounced in the surrogate waste containing
cesium, lead, and strontium, although the specific contaminant(s) was/were not identified,
and could be the nitrate ion instead of or in addition to the metal(s). Cesium is known to
have catalytic properties relative to the decomposition of peroxides. Considerable foaming
and temporary volume expansion was also encountered with the EVE process, more so than
in the OPE process. Apparently, the peroxide catalyst reacted with contaminants in the
waste, releasing oxygen that caused foaming. Foaming could be a problem in large scale
operations, causing porosity in the waste form due to entrapped gas. Although the foam
dissipates during the slow curing process, it leaves surface cracks that may have affected
physical properties in some samples, which could account for lower strength and durability
overall than observed in the OPE resin process.
In summary, leaching results with the EVE resin encapsulation S/S process were uniformly very
good. The resin treated samples appear to be nearly totally impermeable. Unfractured resin
treated samples do not appear to release any contaminants into the environment. They are dust
68
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free and can readily be handled. Unfractured samples should perform very well in either the
TCLP and SPLP test methodologies (if the sample preparation procedure allowed monolith
testing) or in the ANS 16.1 test procedure under certain NRC requirements. Durability and
strength properties for waste forms produced with the OPE process were generally good
compared to cement-based processes, but were much more variable than the results obtained with
the OPE resin encapsulation process. This may have been due to defective samples caused by
foaming during treatment.
Since the EVE resin system does not rely on reaction with contaminants in the waste, it is an
ideal treatment process for use with high concentrations of water soluble contaminants - nitrate
or chloride salts - that cannot be immobilized in conventional S/S processes, as well as lower
concentrations of toxic or radioactive metals that are difficult to stabilize chemically. Such waste
streams would include evaporator residues, such as salt cake, and incineration residues, as well as
dry or nearly dry salt-containing sludges. The salt cake should be crushed to near -100 or -200
mesh particle size prior to encapsulation in resin.
5.10 LIST OF REFERENCES
Conner, J.R. 1990. Chemical Fixation and Solidification of Hazardous Wastes. VanNostrand
Reinhold, New York.
Dow Plastics. 1996. Derakane Epoxy Vinyl Ester Resins. March.
Filter, H.E. 1980. "Polymeric Solidification of Low-Level Radioactive Wastes From Nuclear
Power Plants." Toxic and Hazardous Waste Disposal, Vol 1, R.B. Pojasek, ed., Chap. 14. Ann
Arbor Science Pub., Ann Arbor, MI.
Tyson, D.R. and G.L. Schwendiman. 1995. "Treatability Studies Involving Epoxy
Solidification for Various Mixed Wastes at the Idaho National Engineering Laboratory." Mixed
Waste Proc. Of the Third Biennial Symp. ASME, Baltimore, MD. August 7-10.
69
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70
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6. COMMENTS ABOUT PRETREATMENT STEPS USED IN THIS PROJECT
6.1 CEMENT-BASED SYSTEMS
With the CSA and MP cement S/S systems, the process consisted of two treatment steps
combined into one processing operation:
a. Chemical pretreattnent to reduce hexavalent chromium in the As/Cr-spiked surrogate
wastes to the trivalent state. It was assumed that the cement used in the CSA process
would establish the proper pH regime for the metals.
b. Cement S/S to produce a strong monolith
No size reduction step was used, because it was judged that the aqueous mixing step in
pretreatment would adequately break down any agglomerates into a fairly uniform slurry.
However, it is possible that the poor chromium leaching results in both the TCLP and SPLP
methodologies were due to incomplete agglomerated breakdown.
It was known from previous experience that it is necessary to reduce hexavalent chromium (Cr+6)
(present from the potassium dichromate spiking of the original media) to the trivalent (Cr+3) state
to achieve stabilization of chromium in cement-based waste forms, due to the solubility of Cr+6.
This was done by first acidifying the As/Cr-spiked surrogate waste with phosphoric acid (H3PO4)
solution, then treating the acidified waste with ferrous sulfate (FeSO4) solution, a reducing agent.
It appears that this reduction process was not completely successful, judging from the poor
chromium leaching results in both the TCLP and SPLP, but this may have been due instead to
the incomplete agglomeration breakdown mentioned above. In the case of the Cs/Pb/Sr-spiked
surrogate waste no chemical pretreatment was used. It was assumed that the phosphates used in
the cement itself would act as a stabilization agent for lead. The chemical pretreatments used are
shown in Tables 2-1 and 3-1.
6.2 ORGANIC RESIN ENCAPSULATION SYSTEMS
With organic resin treatment, the process consisted of four treatment steps:
a. Particle size reduction to -1/8 inch (3.2 mm) size
b. Chemical pretreatment to reduce hexavalent chromium to the trivalent state establish the
proper pH regime for metals, and immobilize lead as a phosphate
c. Resin impregnation to completely infiltrate particles
71
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d. Resin encapsulation to fill all voids and produce a strong, impermeable monolith
The first two steps were done as separate processing operations. The latter two steps were done
serially, in a continuous process in the same mixer.
Prior to chemical pretreatment, the surrogate waste was particle size reduced by screening and
crushing to -1/8 inch (3.2 mm), or passing through a number 6 screen. This was required
because the waste contained large amounts of coarse material (>5 mm) that was an artifact of the
waste sample production process. In water-based S/S processes, these agglomerates would
normally be broken up in the mixing process, but it was found that the non-aqueous resin
systems did not wet the agglomerates and thus did not soften them sufficiently to reduce their
particle size. While high-shear mixing did result in some breakdown of large agglomerates, it
was not sufficient to reliably produce -1/8 inch particles. In addition, the EVE resin has a higher
viscosity than water and does not readily penetrate the large agglomerates; therefore, they remain
only macro-encapsulated in the waste form and are potentially teachable to a considerable degree
if the form is cracked or broken, unless the contaminants have been chemically immobilized. In
fact, preliminary experiments proved that fractured samples would not pass the TCLP test
requirements. While such fracturing of these very strong monoliths is probably unlikely in a
reasonable disposal scenario, it was considered to be a possibility that could not be ignored in
this project. It is known from operational experience that size reduction to -1/8 inch is a feasible,
cost-effective procedure in full-scale field operations.
Experiments with emulsifying the resin as a waste-in-resin emulsion did not alleviate the large
agglomerate problem. While agglomerates were broken down to some extent, the now aqueous
contaminants in the waste form were not sufficiently encapsulated. The waste forms so produced
also exhibited lower physical strength.
As stated above, it was necessary to reduce the Cr+6 to Cr+3, With As/Cr-spiked surrogate waste,
this was done by treating the waste with a reducing agent, ferrous sulfate (FeSO4), and with
magnesium oxide (MgO), Ca(OH)2, and cement; water was added to allow the reactions to take
place. In the case of the Cs/Pb/Sr-spiked surrogate waste, phosphoric acid (H3PO4), magnesium
oxide (MgO) and water were used. The phosphoric acid acts as a stabilization agent for lead.
The chemical pretreatments used are shown in Tables 4-1 and 5-1.
It was also determined in preliminary experiments that a resin impregnation step prior to the
encapsulation operation overcame the treatment problems caused by even small, 1/8-inch
agglomerates in the surrogate waste. In the case of the OPE resin treatment, the resin had been
thinned with styrene monomer to reduce its viscosity and allow it to better infiltrate into the
particles. The EVE resin had sufficiently low viscosity that no thinning was required, so no
styrene was used in either the impregnation or encapsulation steps. With both systems, the
uncatalyzed resin was first mixed with the waste and given time to infiltrate, then the catalyst
was added and mixed in. The resin was found to have permeated about one or two millimeters
into large particles, sufficient to completely permeate the 1/8-inch maximum particle size.
72
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APPENDIX A
COMPARATIVE DATA TABLES BY TECHNOLOGY TYPE
73
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PI
i^HHH
Meets Waste Form/Size
Require?
Strength
Long Term Stability
Radiation Stability
Waste Loading
Volume Increase
Table A-l
ROCESS: Calcium Sulfo-Aluminate (CSA) Based-Cement Stabilization
INEEL Soil
Synthetic Soil
Synthetic Sludge
Yes: Can be formulated to meet any required particle size requirement and low to moderate strength waste form.
Monolithic forms have strengths in the range of 100 psi to 700 psi or more at high waste loadings. Strength generally
varies inversely with waste loading and water content, and directly with cement content.
Durability is good, even at high waste
loadings
Durability is poor
Durability is poor to good, depending
on contaminants and test method
Not tested, but should be excellent based on chemistry of process
Up to 50%, depending on durability
and strength requirements
60% to 70%, depending on
contaminants
50% to 70%, depending on
contaminants
10% to 30%, depending on contaminants and water content of surrogate waste
74
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Chromium
Table A-l (Continued)
PROCESS: Calcium Sulfo-aluminate (CSA) Based-Cement Stabilization
Meets newest RCRA LDRs
Did not meet RCRA LDRs in this project, due to failure of pretreatment. Capable of meeting LDRs.
Cesium
No LDRs, but is not significantly reduced in this process
Lead
Meets newest RCRA LDRs
No LDRs, but is not significantly reduced in this process
Arsenic
Chromium
Cesium
Lead
Strontium
Low and significantly reduced
High, due to failure of pretreatment. Capable of better results.
Not significantly reduced in this process
Moderate
Not significantly reduced in this process
High, due to failure of pretreatment. Capable of better results.
75
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Table A-l (Continued)
PROCESS: Calcium Sulfo-aluminate (CSA) Based-Cement Stabilization
8fl^^^9^HHHB^HHliHiH
^B^l^^HHSHH^HifliHE
Containment of Salts
Pretreatment
Residuals
Throughput
Cost:
Capital
Process
Chemicals/Materials
Total
Availability:
Equipment
Process
INEEL Soil
Synthetic Soil
Synthetic Sludge
Not tested, but judged to be poor for high levels
Required for Cr**, Cs, Sr. Not required for As. May be required for lead and some other RCRA metals
None
Typical throughput in large-scale remedial projects is 100 tons or ydVhr for ex-situ treatment. Fixed installations can be
any size.
Based on experience with hazardous waste, amortized capital costs are low, generally less than 5% of total vendor price in
large-scale projects. Capital cost of LLMW would likely be considerably higher. Actual process equipment cost for
treatment units varies from $10,000 to $500,000, depending on scale, not including special handling requirements for
LLMW.
Based on experience with hazardous waste, labor, utilities, etc. are typically about
remedial projects.
20% of the total vendor price in
Based on experience with hazardous waste, chemical costs are typically 40% of the total vendor price in remedial
projects. CSA cement formulations are considerably more expensive than Portland cement - about $180/ton vs about
$70/ton. Based on cement/waste ratios of about 15%, chemical costs are about $27/ton of waste treated.
Based on experience with hazardous waste, total vendor prices in remedial projects range from $60/yd3 to $220/yd3,
exclusive of excavation, handling and disposal. Treatment of small quantities of waste will have much higher unit costs.
Large-scale treatment of mixed wastes can be expected to cost $100/yd3 or more.
Equipment is readily available in all sizes and scales. Most equipment is off-the-shelf, and available on short notice.
Nearly all process formulations are available generically. Some proprietary versions exist, but are usually not necessary,
and are generally available as formulated additives.
76
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P]
jBafjjillljJI Iglsljjlli jj^TOftftflSfflB^w^^^^^^EffifiHwrlRiiB^^TO
Complexity
Robustness
Scale Proven
Ease of Permit
& Public Approval
Comments
Table A-l (Continued)
ROCESS: Calcium Sulfo-aluminate (CSA) Based-Cement Stabilization
INEEL Soil
Synthetic Soil
Synthetic Sludge
Processes are simple and easily carried out with normal industrial equipment and personnel skills. Hazards, other than the
waste itself and certain additives and reagents, are primarily those of moving mechanical devices - mixers, conveyors, etc.
Maintenance and repair are conventional and routine.
Equipment is very robust. Processes are generally forgiving in operation, not requiring any high or unusual degree of
control to meet QA/QC standards.
Cement-based processes are proven at a commercial scale on every type of hazardous and radioactive waste, and on many
LLMW types.
Should be about average for waste treatment facilities. No high temperature or pressures, no air emissions other than dust
and possibly from the waste itself, no water effluents. Environmental release very unlikely. Product is in an acceptable
form in terms of public attitude.
General process is well proven and available at low cost. As with all stabilized waste forms, long-term durability is not
well defined as a property or test, but long-term experience with concrete gives an added measure of confidence.
77
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Table A-2
PROCESS: Magnesium Phosphate (MP) Based-Cement Stabilization
••••
Meets Waste Form/Size
Require?
Strength
Long Term Stability
Radiation Stability
Waste Loading
Volume Increase
INEEL Soil
Synthetic Soil
Synthetic Sludge
Yes: Can be formulated to meet any required particle size requirement and low to moderate strength waste form.
Monolithic forms have strengths in the range of 30 psi to 180 psi or more at high waste loadings. Strength generally
varies inversely with waste loading and water content, and directly with cement content
Durability is poor at the low cement addition ratios used in the tests. Higher ratios may improve durability.
Not tested, but should be excellent based on chemistry of process.
Up to 50%, depending on durability
and strength requirements
60% to 70%, depending on
contaminants
50% to 70%, depending on
contaminants
10% to 30%, depending on contaminants and water content of surrogate waste
78
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Arsenic
Table A-2 (Continued)
PROCESS: Magnesium Phosphate (MP) Based-Cement Stabilization
High: does not meet newest RCRA LDRs
Chromium
Did not meet RCRA LDRs in this project, due to failure of pretreatment. Should be capable of meeting LDRs.
Cesium
No LDRs, but is not significantly reduced in this process
Lead
High: does not meet newest RCRA LDRs
Meets newest RCRA LDRs
Strontium
No LDRs, but is not significantly reduced in this process
Arsenic
Chromium
Cesium
Lead
Strontium
Relatively low and significantly reduced
High, due to failure of pretreatment. Capable of better results.
Some reduction
Very low.
Some reduction
Not significantly reduced
High, greater than untreated waste
Not significantly reduced
79
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Table A-2 (Continued)
PROCESS: Magnesium Phosphate (MP) Based-Cement Stabilization
Containment of Salts
Pretreatment
Residuals
Throughput
Cost:
Capital
Process
Chemicals/Materials
Total
Availability:
Equipment
Process
INEEL Soil
Synthetic Soil Synthetic Sludge
Not tested, but judged to be poor for high levels
Required for As, Cr4*, Cs, Pb, Sr. May be required for some other RCRA metals.
None
Typical throughput in large-scale remedial projects is 100 tons or yd3/hr for ex-situ treatment. Fixed installations can be
of virtually any size.
Based on experience with hazardous waste, amortized capital costs are low, generally less than 5% of total vendor price in
large-scale projects.. Capital cost of LLMW would likely be considerably higher. Actual process equipment cost for
treatment units varies from $10,000 to $500,000, depending on scale and not including special handling requirements for
LLMW
Based on experience with hazardous waste, labor, utilities, etc. are typically about 20% of the total vendor price in
remedial projects.
Based on cement price of $0.38/lb, and cement/waste ratios of about 0. 15, chemical costs would be $1 14/ton of waste
treated, not including pretreatment chemicals.
Based on experience with hazardous waste, total vendor price with the MP process in remedial projects would range from
about $140/yd3 to $300/yd3, exclusive of excavation, handling and disposal. Treatment of small quantities of waste will
have much higher unit costs. Large-scale treatment of mixed wastes can be expected to cost $200/yd3 or more.
Equipment is readily available in all sizes and scales. Most equipment is off-the-shelf, and available on short notice.
Proprietary reagent used in this project.
Generic formulations known., but patent situation unclear.
80
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Complexity
Robustness
Scale Proven
Ease of Permit
& Public Approval
Comments
Table A-2 (Continued)
PROCESS: Magnesium Phosphate (MP) Based-Cement Stabilization
INEEL Soil Synthetic Soil Synthetic Sludge
Processes are simple and easily carried out with normal industrial equipment and personnel skills. Physical hazards are
primarily those of moving mechanical devices - mixers, conveyors, etc. Chemical hazards , other than the waste itself, are
certain additives and reagents used in pretreatment, and release of ammonia from the cement binder. Maintenance and
repair are conventional and routine.
Equipment is very robust. Processes are generally forgiving in operation, not requiring any high or unusual degree of
control to meet QA/QC standards.
Cement-based processes are proven at commercial scale on virtually every type of hazardous and radioactive waste, and
on many LLMW types. While this cement is unconventional, it should not significantly affect operation except for
possible APC requirement for ammonia.
Should be about average for waste treatment facilities. No high temperature or pressure processes, no air emissions other
than dust, ammonia, and possibly from the waste itself, no water effluents. Environmental release very unlikely. Product
is in an acceptable form in terms of public attitude.
General processing is well proven and available at low cost, but the magnesium phosphate binder has not been used
commercially and is relatively expensive. As with all stabilized waste forms, long-term durability is not well defined as a
property or test, and durability for this process is uncertain.
81
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Table A-3
PROCESS: Orthophthalic Polyester (OPE) Resin Encapsulation
••••1
Meets Waste Form/Size
Require?
Strength
Long Term Stability
Radiation Stability
Waste Loading
Volume Increase
INEEL Soil
Synthetic Soil
Synthetic Sludge
Yes: Can be formulated to meet any required particle size requirement and high strength waste form.
Monolithic forms have strengths in the range of 3200 psi to 7200 psi or more at low waste loadings. Higher waste
loadings possible, but not tested.
Durability is excellent at waste loadings tested.
Not tested, but should be good based on prior work with similar systems
Ranged from about 30% to 55%, depending primarily on weight increases due to pretreatment.
75% to greater than 200%, depending primarily on volume increases due to pretreatment
82
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Arsenic
Table A-3 (Continued)
PROCESS: Orthophthalic Polyester (OPE) Resin Encapsulation
Meets newest RCRA LDRs
Chromium
Meets newest RCRA LDRs
Cesium
No LDRs, but significantly reduced in this process
Lead
Meets newest RCRA LDRs
Strontium
No LDRs, but significantly reduced in this process
Arsenic
Chromium
Cesium
Lead
Strontium
Very low and sigmticantly reduced
Low and significantly reduced
Significantly reduced in this process
Very low and significantly reduced
Significantly reduced in this process
83
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Table A-3 (Continued)
PROCESS: Orthophthalic Polyester (OPE) Resin Encapsulation
••••
Containment of Salts
Pretreatment
Residuals
Throughput
Cost:
Capital
Process
Chemicals/Materials
Total
Availability:
Equipment
INEEL Soil
Synthetic Soil
Synthetic Sludge
Not tested, but judged to be excellent for all levels of salts.
Required because of TCLP test methodology, probably not required in monolith tests such as ANS 16.1. Elimination or
reduction would significantly improve economics of this process.
None
No experience with this type of process. Probably less than conventional cement-based processes, especially if the resin
soak step is required, in which case the process would likely be batch-type. If pretreatment and resin soak are eliminated
by size reduction of waste, throughput could approach that of conventional processes, since the only S/S treatment step
would be mixing - size reduction pretreatment is not expected to reduce throughput.
Based on experience with hazardous waste, amortized capital costs are low, generally less than 5% of total vendor price in
large-scale projects. The OPE process would use the same basic equipment, except possibly for size reduction. Capital
cost of LLMW would likely be considerably higher. Actual process equipment cost for treatment units varies from
$10,000 to $500,000, depending on scale and not including special handling requirements for LLMW.
Based on experience with hazardous waste, labor, utilities, etc. are typically about $20/ton to $40/ton in remedial projects.
This may increase thousand fold or higher for salt containing LLMW. Pretreatment would likely increase process costs
for the OPE process.
Based on resin price of $1.50/lb, and resin/waste ratios of about 0.5 to 1.4, chemical costs would be $1500/ton to
$4200/ton of waste treated, not including pretreatment chemicals. Elimination of pretreatment, replacing it with size
reduction alone, could reduce this cost by at least half.
Because of the extremely high chemical costs, total cost for the OPE process would be at least $ 1600/ton based on the
processing used in the test work. Elimination of pretreatment, replacing it with size reduction alone, could reduce this
cost by at least half.
Equipment is readily available in all sizes and scales. Most equipment is off-the-shelf, and available on short notice.
84
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Process
Complexity
Robustness
Scale Proven
Ease of Permit
& Public Approval
Comments
Table A-3 (Continued)
PROCESS: Orthophthalk Polyester (OPE) Resin Encapsulation
INEEL Soil Synthetic Soil Synthetic Sludge
The resins used are available in commercial bulk quantities from more than one source in the U.S.
Processes are simple and easily carried out with normal industrial equipment and personnel skills. Physical hazards are
primarily those of moving mechanical devices - mixers, conveyors, etc. Chemical hazards, other than the waste itself and
certain pretreatment additives and reagents, are those of organic vapors and flammability. The resins are widely used
industrially, so safety and handling should not pose any unusual problems. Maintenance and repair are conventional and
routine.
Equipment is very robust. Processes are generally forgiving in operation, not requiring any high or unusual degree of
control to meet QA/QC standards. However, mixing of waste, resin and catalyst will likely be more critical than
equivalent operations in cement-based processes.
Organic, thermosetting polymer processes have not been proven at commercial scale on any type of hazardous or
radioactive wastes, or LLMW.
Should be about average for waste treatment facilities. No high temperature or pressure processes and no water effluents.
Air emissions, other than possibly from the waste itself, consist of organic vapors that may be hazardous, but which are
commonly encountered and handled in the normal industrial uses of the resin. Other environmental release very unlikely.
Product is in an acceptable form in terms of public attitude.
Stabilized waste forms, long-term durability is not well defined as a property or test, but the test results from this project,
coupled with long-term experience with products made from mis resin, give a reasonable measure of confidence.
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••••
Meets Waste Form/Size
Require?
Strength
Long Term Stability
Radiation Stability
Waste Loading
Volume Increase
Table A-4
PROCESS: Epoxy Vinyl Ester (EVE) Resin Encapsulation
INEEL Soil Synthetic Soil Synthetic Sludge
Yes: Can be formulated to meet any required particle size requirement and moderate to high strength waste form.
Monolithic forms have strengths in the range of 50 psi to 2100 psi or more at low waste loadings. Higher waste loadings
possible, but not tested.
Durability is good to excellent for most samples at waste loadings tested, but varies considerably with resin addition ratio.
Durability of some samples was poor to marginal.
Not tested, but should be good based on prior work with similar systems
Ranged from about 30% to 55%, depending primarily on weight increases due to pretreatment
75% to greater than 200%, depending primarily on volume increases due to pretreatment
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Arsenic
Table A-4 (Continued)
PROCESS: Epoxy Vinyl Ester (EVE) Resin Encapsulation
Meets newest RCRA LDRs
Chromium
Meets newest RCRA LDRs
Cesium
No LDRs, but significantly reduced in this process
Lead
Meets newest RCRA LDRs
Strontium
No LDRs, but significantly reduced in this process
Arsenic
Chromium
Cesium
Lead
Strontium
Very low and significantly reduced
Low and significantly reduced
Significantly reduced in this process
Very low and significantly reduced
Significantly reduced in this process
87
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Table A-4 (Continued)
PROCESS: Epoxy Vinyl Ester (EVE) Resin Encapsulation
I^HHI^^^BH^^BlH^^^^^Bm^^^^B
Containment of Salts
Pretreatment
Residuals
Throughput
Cost:
Capital
Process
Chemicals/Materials
Total
Availability:
Equipment
INEEL Soil
Synthetic Soil
Synthetic Sludge
Not tested, but judged to be excellent for all levels of salts.
Required because of TCLP test methodology, probably not required in monolith tests sucb as ANS 16.1. Elimination or
reduction would significantly improve economics of this process.
None
No experience with this type of process. Probably less than conventional cement-based processes, especially if the resin
soak step is required, in which case the process would likely be batch-type. If pretreatment and resin soak are eliminated
by size reduction of waste, throughput could approach that of conventional processes, since the only S/S treatment step
would be mixing - size reduction pretreatment should not be the slow step).
Based on experience with hazardous waste, amortized capital costs are low, generally less than 5% of total vendor price in
large-scale projects. The OPE process would use the same basic equipment, except possibly for size reduction. Capital
cost of LLMW would likely be considerably higher. Actual process equipment cost for treatment units varies from
$10,000 to $500,000, depending on scale and not including special handling requirements for LLMW.
Based on experience with hazardous waste, labor, utilities, etc. are typically about
Pretreatment would likely increase process costs for the OPE process.
$20/ton to $40/ton in remedial projects.
Based on resin price of $1.65/lb, and resin/waste ratios of about 0.5 to 1.4, chemical costs would be $1600/ton to
$4600/ton of waste treated, not including pretreatment chemicals. Elimination of pretreatment, replacing it with size
reduction alone, could reduce this cost by at least half.
Because of the extremely high chemical costs, total cost for the OPE process would be at least $1700/ton based on the
processing used in the test work. Elimination of pretreatment, replacing it with size reduction alone, could reduce this
cost by at least half.
Equipment is readily available in all sizes and scales. Most equipment is off-the-shelf, and available on short notice.
88
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Table A-4 (Continued)
PROCESS: Epoxy Vinyl Ester (EVE) Resin Encapsulation
Process
Complexity
Robustness
Scale Proven
Ease of Permit
& Public Approval
Comments
INEEL Soil
Synthetic Soil
Synthetic Sludge
The resins used are available in commercial bulk quantities from more than one source in the U.S.
Processes are simple and easily carried out with normal industrial equipment and personnel skills. Physical hazards are
primarily those of moving mechanical devices - mixers, conveyors, etc. Chemical hazards, other than the waste itself and
certain pretreatment additives and reagents, are those of organic vapors and flammability. The resins are widely used
industrially, so safety and handling should not pose any unusual problems. Maintenance and repair are conventional and
routine. Provision may need to be made to reduce foaming.
Equipment is very robust. Processes are generally forgiving in operation, not requiring any high or unusual degree of
control to meet QA/QC standards. However, mixing of waste, resin and catalyst will likely be more critical than
equivalent operations in cement-based processes.
Organic, thermosetting polymer processes have not been proven at commercial scale on any type of hazardous or
radioactive wastes, or LLMW.
Should be about average for waste treatment facilities. No high temperature or pressure processes and no water effluents.
Air emissions, other than possibly from the waste itself, consist of organic vapors that may be hazardous, but which are
commonly encountered and handled in the normal industrial uses of the resin. Other environmental release very unlikely.
Product is in an acceptable form in terms of public attitude.
General process has not been proven at commercial scale, and may be very expensive. As with all stabilized waste forms,
long-term durability is not well defined as a property or test, but the test results from this project, coupled with long-term
experience with products made from this resin, give a reasonable measure of confidence.
89
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90
-------
APPENDIX B
COMPARATIVE DATA GRAPHS BASED ON TEST RESULTS
91
-------
The following figures (B-l through B-16) compare the results of the various test methods used to
evaluate the efficacy of the four processes investigated in this project. Each figure shows the
data for a single parameter - metal leaching, wet/dry or freeze/thaw resistance, and unconfined
compressive strength - with each of the four processes on the three different waste types. The
data in each case are averages of three replicate tests, and are taken from Tables 2-2, 3-2,4-2 and
5-2 in the text. For the wet/dry, freeze/thaw resistance and unconfined compressive strength
figures (B-l 1 thorough B-16), the test results are shown for the two different spiked wastes for
each of the three waste types, since the spiking resulted in considerably different physical
properties in some cases. The TCLP figures (B-l, B-2 and B-4) indicate the required values
under the current LDRs for arsenic, chromium, and lead.
It should be noted that the Y-axes of the arsenic, chromium, and lead graphs is logarithmic
because of the very wide variation in data values. This tends to distort the visual comparisons
from one bar to another, a fact which must be taken into account in evaluating these results. All
of the other graphs have normal Y-axes, with no visual distortion.
92
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Figure B-l
TCLP - Results Comparison
Arsenic Concentration
100
0.001
INEEL
S. Soil S. Sludge
Waste Type
CSA Process HI MP Process
OPE Process EVE Process
J
93
-------
Figure B-2
TCLP - Results Comparison
Chromium Concentration
100
4= 0.1 v
0.001
INEEL
S. Soil S. Sludge
Waste Type
CSA Process • MP Process
OPE Process Hi EVE Process
94
-------
Figure B-3
50
Is 40
c 30
I 20
-------
Figure B-4
TCLP - Results Comparison
Lead Concentration
100
0.001
INEEL S. Soil S. Sludge
Waste Type
CSA Process H MP Process ff OPE Process gg EVE Process |
96
-------
Figure B-5
TCLP - Results Comparison
Strontium Concentration
1NEEL
S. Soil
Waste Type
S. Sludge
CSA Process
WIP Process
OPE Process III EVE Process
97
-------
Figure B-6
SPLP - Results Comparison
Arsenic Concentration
100
0.001
INEEL S. Soil S. Sludge
Waste Type
CSA Process BJ MP Process Hi OPE Process F~1 EVE Process I
98
-------
Figure B-7
SPLP - Results Comparison
Chromium Concentration
O)
E
100
10
1
I 0.1
-------
Figure B-8
SPLP - Results Comparison
Cesium Concentration
INEEL
S. Soil
Waste Type
S. Sludge
• CSA Process |
|MP Process
• OPE Process
ill |
EVE Process |
100
-------
Figure B-9
SPLP - Results Comparison
Lead Concentration
100
0.001
INEEL S. Soil S. Sludge
Waste Type
• CSA Process •
II MP Process
B OPE Process
LJ
I EVE Process I
101
-------
Figure B-10
50
40
30
£20
CD
O
O
O
10
SPLP - Results Comparison
Strontium Concentration
INEEL
S. Soil
Waste Type
S. Sludge
CSA Process
MP Process
OPE Process
EVE Process
102
-------
Figure B-ll
WET/DRY - Results Comparison
As/Cr Spiked Wastes
INEEL
S.Soil
Waste Type
S. Sludge
CSA Process
MP Process
OPE Process
EVE Process
103
-------
Figure B-12
WET/DRY - Results Comparison
Cs/Pb/Sr Spiked Wastes
INEEL
S. Soil
Waste Type
S. Sludge
CSA Process BJ MP Process J OPE Process |j| EVE Process |
104
-------
Figure B-13
FREEZE/THAW - Results Comparison
As/Or Spiked Wastes
4— •
£2
O)
<1>
>
>
£1
0
_ |
••h
#
110
100
90
80
70
60
50
40
30
20
10
0
INEEL
S. Soil
Waste Type
S. Sludge
CSA Process iH MP Process J OPE Process [ I EVE Process |
105
-------
Figure B-14
FREEZE/THAW - Results Comparison
Cs/Pb/Sr Spiked Wastes
+-J
c
O)
0
>
>
to
0
_J
^^
#
110
100
90
80
70
60
50
40
30
20
10
0
INEEL
S. Soil
Waste Type
S. Sludge
CSA Process B3 MP Process • OPE Process jij§ EVE Process I
106
-------
Figure B-15
UCS - Results Comparison
As/Cr Spiked Wastes
INEEL
S. Soil
Waste Type
S. Sludge
CSA Process
MP Process
OPE Process
EVE Process
107
-------
Figure B-16
UCS - Results Comparison
Cs/Pb/Sr Spiked Wastes
INEEL
S. Soil
Waste Type
S. Sludge
CSA Process
MP Process
OPE Process
EVE Process
108
-------
APPENDIX C
PRESENT RCRA LDR REQUIREMENTS OF METALS
109
-------
Table C-l
Original and Present RCRA LDR Metals Leaching Levels, TCLP Test
TC Metal
Antimony
Arsenic
Barium
Beryllium
Cadmium
Chromium
Lead
Mercury (all others, D009)
Nickel
Selenium
Silver
Thallium
Vanadium
Zinc
RCRA
Code
D004
D005
D006
D007
D008
D009
D010
D011
Original TC Level
(mg/1, TCLP)
5.00
100.00
1.00
5.00
5.00
0.20
1.00
5.00
Final UTS TC Level
(mg/1, TCLP)
Federal Register 63, No. 100.
May 26, 1998
1.15
5.00 (unchanged)
21
1.22
0.11
0.60
0.75
0.025
11
5.7
0.14
0.2
1.6
4.3
110
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APPENDIX D
COLLECTION AND PREPARATION OF MEDIA SAMPLES
111
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D.I COLLECTION OF MEDIA SAMPLES
Idaho National Engineering and Environment Laboratory (INEEL) Soil;
On April 30, 1997, representatives from EPA and contractors joined representatives from the
Idaho National Engineering and Environment Laboratory (INEEL) to collect site specific soil
samples. These samples were obtained from a location approximately 55 miles west of Idaho
Falls, Idaho, at an area a few miles southwest of the INEEL Radioactive Waste Management
Complex (RWMC) where clean fill could be obtained. Three 55-gallon drums were filled with
soil that had been obtained from a depth of approximately 3-5 feet below grade. These soil
samples consisted of a moderately drained approximately 50/50 clay/sand mixture. It was an
exceptionally clean soil with no organic matter observed in the samples taken. The drums
containing the soil samples were labeled and left at INEEL to be shipped within 24 hours for
further characterization and contaminant spiking.
Westinghouse Savannah River Site (\\ SRS) Area Soil:
After numerous attempts to contact Westinghouse Savannah River Site (WSRS) personnel failed,
an alternative source of soil samples was researched. When maps of the WSRS area were
examined with reference to the same soil type, it was observed that several clay pits existed
within the area of the target soil type, approximately 15 miles north, northwest of the WSRS
boundary. The WSRS site is 25 miles east of Augusta, Georgia, and 65 miles west of Columbia,
South Carolina. In May 1997, arrangements were made with the pit personnel at these clay pits
to obtain soil samples. Three 55-gallon steel drums were filled with soil samples from the
undisturbed overburden soil located south of the pit operation. The soil samples were consistent
with those mapped near the industrial areas of the WSRS. These samples consisted of well
drained sandy soil collected from a depth of approximately 0.5 to 1.0 feet below existing grade.
Care was taken to minimize the organic content of the samples. However, trace amounts of root
fibers were observed. These samples were immediately shipped for further characterization and
contaminant spiking.
Synthetic Soil;
In August 1997, synthetic soil was produced from a recipe provided by the EPA's Risk
Reduction Engineering Laboratory located in Edison, New Jersey.
The synthetic soil mixture (utersol) contained the following by weight:
Sand at 31%
No. 9 gravel at 6%
Silt at 28%
Topsoil at 20%
Kaolinite at 15%
112
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Synthetic Sludge:
In August 1997, synthetic sludge was produced from a recipe provided by the Department of
Energy's Fernald site located in Fernald, Ohio.
The synthetic sludge contains the following by weight:
Sand at 30%
Silt at 20%
Al2O3at34%
Ca(OH)2 at 4%
MgO at 12%
D.2 PRE-TREATMENT ANALYTICAL TREATMENT
Prior to spiking all sample types, the following chemical and physical testing was completed.
Dry Screen, weight %
Cation exchange capacity (CEC)
Organic carbon content
Alkalinity
Atterberg limits
Moisture content
Unconfined compressive strength
Proctor compaction
Summaries of these procedures are provided below.
Volumetric Determination of Water Soluble Bicarbonate. Carbonate and Hydroxide - This
method is used to determine the concentration of bicarbonate, carbonate, and hydroxide in solid
or liquid samples. The sample is dissolved in deionized water and then filtered. The resulting
filtrate is titrated with acid to a pH 8.3 and a pH 4.5. Concentrations of 0.05 percent or greater in
solids and 0.01 grams per liter in liquids can be reported using this method. The presence of
soluble borates, phosphates, cyanides and silicates will result in positive interferences, for which
the method contains no provision for addressing.
Organic Carbon (Solids) - This procedure involves the determination of total carbon and
inorganic carbon in separate steps. The total organic carbon is calculated as the difference
between the total carbon and the inorganic carbon. The total carbon is determined using a non-
dispersive, infrared instrument designed to measure the carbon content, among other elements, of
solid samples. The solid sample is combusted, the resulting elemental carbon is converted to
CO2, and analyzed using an infrared scan. Inorganic carbon is determined using an analytical
113
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procedure for the Determination of Inorganic Carbon by Coulometry. Solid or liquid samples are
reacted with a strong mineral acid to evolve the inorganic carbon as CO2. The CO2 is passed to
the coulometer cell where it is converted to an acid and then neutralized. The equivalent amount
of inorganic carbon is calculated using the titration results. Inorganic carbon concentrations of
0.005 percent or greater in solids and 0.5 milligrams per liter or greater in solutions can be
determined using this method.
Dry Screen/weight % - Dry screen analyses are performed by placing the sample to be sieved
on the top of nested, standard, 8-inch diameter sieves of the selected sizes with a bottom pan
fitted to the bottom sieve. The sieve nest is clamped into a mechanical shaking device, and
shaken for a period of time which can vary, usually from 3 to 30 minutes. The screening time is
usually defined as the time when additional periods of shaking fail to change the weight of the
material on any screen by more than 0.3%. When screening is completed, the material retained
on each screen and in the bottom pan is weighed and calculated as a percentage of the total
sample.
SW-846 Method 9045C. Soil and Waste pH - This method is used for the measurement of pH
in soil and solid, sludge or non-aqueous waste samples. The method is not appropriate for waste
samples containing greater than 20 percent water by volume. Samples are mixed with reagent
water and the pH of the resulting solution is determined using a pH meter equipped to allow for
temperature compensation. For samples with a pH higher than 10, the measured pH may be
biased low, while for samples with a pH lower than 1, the measured pH may be biased high. For
analysis of oily waste samples, particular care must be taken to prevent the pH meter electrodes
from becoming coated, which will result in erroneous measurements.
Method 19. Cation-Exchange-Capacity - This method is used to measure the tendency of a soil
sample to exchange weakly held cations for cations in a solution. The soil sample is first washed
with a basic sodium acetate solution and then washed with 95 percent ethanol. The adsorbed
sodium is then displaced through washing of the soil sample with a neutral ammonium acetate
solution. Finally the sodium concentration in the extracts from the washing procedure is
determined using a separate analytical procedure.
ASTM Method D 698-91. Standard Test Method for Laboratory Compaction
Characteristics of Soil Using Standard Effort (12.400 ft-lbf/ftVeOO kN-m/m3)) - This
procedure details the procedures to be used to perform compaction tests in a laboratory to
determine the relationship between the water content and dry unit weight of soils, the compaction
curve. The compaction procedure consists of placing a soil sample, at a selected water content,
in three layers in a mold of given dimensions, with each layer compacted by 25 or 56 blows of a
5.5-lbf (24.4-N) rammer dropped a distance of 12 inches (305 millimeters). The resulting dry
unit weight is then determined. This process is repeated for a sufficient number of soil samples
at varying water contents to establish a relationship between the dry unit weight and the water
content of the soil, in order to plot the compaction curve. The optimum water content and
standard maximum dry unit weight are determined from the resulting compaction curve.
114
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Corrections to the results must be made for soil specimens which contain greater than 5 percent
by weight coarse fraction, if the coarse material is not included in the test. In addition, if the
method is used for free draining soils, the maximum unit weight may not be well defined, and
may be less than determined using ASTM Method D 4253.
ASTM Method D 2166-98a. Unconfined Compressive Strength of Cohesive Soil - This
method provides an approximate value of the compressive strength of soils that possess sufficient
cohesion to allow testing in the unconfined state. The method is applicable for use with cohesive
soils in the undisturbed, remolded, or compacted condition, which do not expel water upon
compaction or deformation, and retain intrinsic strength upon removal of confining stresses. The
method is typically used for soils such as clays or cemented soils, but not for dry and crumbly
solids, silts, peats, or sands. The approximate compressive strength, in terms of total stresses, is
determined using strain-controlled application of the axial load to in terms of total stresses. The
results to be reported following this test vary depending upon the properties of the soil specimen
and include observations, notes and drawing to be prepared by the person performing the test.
The appendix to the method provides an example Data Reporting Sheet.
ASTM Method D 33Q2-97a. Standard Test Method for Total Moisture in Coal - This test
method is based on the loss in weight of a coal sample in an air atmosphere under rigidly
controlled conditions of temperature, time, and airflow. The moisture sample is crushed and
divided. The crushed and divided moisture sample is air dried to equilibrate it with the
atmosphere in which further division and reduction are to occur. Residual moisture
determination is made in a heated forced-air circulation oven under rigidly defined conditions.
Total moisture is calculated from loss (or gains) in air drying and the residual moisture.
ASTM Method D 4318-95a. Standard Test Method for Liquid Limit. Plastic Limit, and
Plasticity Index of Soils - These procedures are used to determine the liquid limit, plastic limit,
and plasticity index of soil samples. The liquid limit and plastic limit, along with the shrinkage
limit, are often referred to as the Atterberg limits, which are used to distinguish the boundaries of
the several consistency states of plastic soils. The first step of the process involves removal of
any material from the soil sample that is retained on a 425-[im (No. 40) sieve. The liquid and
plastic limits of many soils are considerably different for dried samples to dried samples. If the
results obtained from these procedures are to be used to estimate or correlate the engineering
behavior of a soil in the moist, natural state, samples should not be allowed to dry before testing
unless dried sample results are specifically desired.
The liquid limit is determined by spreading a portion of the sample in a brass cup, dividing the
sample in two using a grooving tool, and allowing the sample to flow together from the shocks
caused by repeatedly dropping the cup in a standard mechanical device. Multiple trials are
performed at varying soil sample water contents following either Method A or Method B, as
described in the method. Under Method A, three or more trials over a range of water contents
are performed, and the resulting data is plotted or calculated to determine the liquid limit. For
Method B, data from two trials at one water content are multiplied by a correction factor to
115
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determine the liquid limit. Method A, the multipoint method, is generally more precise, and is
recommended for use in cases where greater precision is required or the results are likely to be
subject to dispute. Method B requires significant judgement by the operator and, therefore,
should only be conducted by an experienced operator. In addition, the Method B calculations are
based on correlations which may not be valid for organic soils or soils from a marine
environment.
The plastic limit is determined by alternately pressing together and rolling into a 3.2-millimeter
diameter thread a small portion of the soil until its water content is reduced to the point at which
the thread crumbles and can no longer be pressed together and rerolled. The water content of the
soil sample at this point is reported as the plastic limit. The plasticity index is calculated as the
difference between the liquid limit and the plastic limit. The results for this analysis typically
reported are the liquid limit, plastic limit and plasticity index to the nearest whole number. If the
liquid limit or plastic limit tests could not be performed, or if the plastic limit is equal to or
greater than the liquid limit, the soil is reported to be non-plastic, NP. In addition, the reported
results should indicate the percentage of the soil sample retained on the 425 \im (No, 40) sieve
and the procedure used to determine the liquid limit.
Table D-l provides the pre-treatment testing results.
116
-------
Table D-l Frc-Ti eatmenf Soil Analytical Results
• • -.PARAMETER;:;- v. : :,:
Dry Screen, wt %
Plus Yi inch
'/2 by 14 inch
V* inch by 6 Mesh
Minus 6 Mesh
pH of 50% Solution
Alkalinity, % NaOH
Alkalinity, % CO3
Alkalinity, % HCO3
CEC meg/100g
EVEEL •.-••• •:
SOIL
6.09
12.54
8.72
72.65
8.42
<0.4
0.14
0.29
23.9
SRSSQIL
SYNTHETIC
::;:;::::;v.:.;S(Mi,;-;-:- :;:":
SYNTHETIC
•:; .SLUDGE :
0.00
4.64
4.44
90.92
5.52
<0.4
<0.14
0.14
1.2
0.00
2.32
5.75
91.93
8.17
<0.4
<0.14
0.14
30.2
0.00
0.00
1.88
98.12
12.44
0.84
0.20
<0.14
0.4
Organic carbon content
Total Carbon, %
Carbonate Carbon, %
Organic Carbon, %
Atterberg limits
Liquid limit
Plastic limit
Plasticity Index
Atterberg Classification
Moisture content, %
1.69
1.09
0.60
43.3
16.9
26.4
CL
18.4
1.32
0.01
1.31
NP
NP
NP
NP
7.5
0.39
0.02
0.37
24.6
13.7
10.9
CL
9.5
0.45
0.29
0.16
31.2
22.7
8.5
CL
12.5
Unconfined compressive strength
Total Stress, PSF
Axiai Strain, %
5068
2.37
458
1.17
5725
2.62
9375
4.08
Proctor Compaction
Optimum Moisture Content, %
Maximum Dry Density, pcf
18.7
100.7
7.9
121.9
9.6
121.9
14.9
113.7
Key:
CL = Lean clay
NP = Non-plastic
• = Although organic carbon content testing was performed pretreatment, it was not
performed posttreatment because none of the additives contained organic matter.
Therefore, the organic carbon content remained the same.
117
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118
-------
APPENDIX E
PREPARATION OF CONTAMINATED MEDIA (SURROGATE WASTE) SAMPLES
119
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E,l DOSE-RESPONSE BENCH-SCALE TESTING
A dose-response bench-scale study was conducted during May and June 1997. The purpose of
the bench-scale study was to develop characteristic dose-response curves for the INEEL soil and
SRS soil with respect to the contaminants which would be used throughout the treatability study.
With the aide of the characteristic curves, decisions could then be made as to contaminant
specific spike concentrations and spiking strategy to be used in bulk sample preparation. The
intent of the dose-response bench-scale study was to provide sufficient signal (contaminant) to be
differentiated from the noise (analytical method tolerance), and yet not spike the samples with
such great contaminant loads as to be unrealistic
In general, the dose-response bench-scale study consisted of contaminant spiking the INEEL and
SRS soils at three dosage levels: 1,000, 10,000, and 30,000 milligrams per kilogram (mg/kg) of
arsenic, cesium, chromium (VI), lead, and strontium. These five heavy metals were selected by
EPA to serve as surrogates for radionuclides. Radionuclides were not chosen as contaminants
due to safety, handling, and disposal issues, as well as the difficulty in locating laboratories that
analyze radioactive samples, and the fact that radioactive sample contamination increases
analytical costs substantially. The resulting spiked soils were analyzed for total metals content
and leachable metals as determined by the TCLP test.
Spiking was done with aqueous solutions of soluble metal salts. To prevent precipitation of
metals in the spiking mixture, the cations (lead, strontium, and cesium) and anions (arsenic and
chromium (VI)) were added as separate solutions to separate soil samples. These combinations
of contaminants were selected to maximize solubility and minimize precipitation of the
contaminants from solution.
E.2 BULK SAMPLE SPIKING
After considerable experimentation, a bulk sample spiking strategy was developed that would
ensure adequate leachable concentrations of the metals in the TCLP and SPLP testing
methodologies before S/S treatment. To prevent interactions among the metal solutions, two
different spiking solutions were used. One contained potassium dichrornate (K2Cr2O7) and
sodium arsenate (Na2HAsO4(7H2O)); the other cesium nitrate (CsNO3), lead nitrate (Pb(NO3)2),
and strontium nitrate (Sr(NO3)2). This resulted in eight surrogate wastes to be tested. No
significant levels of other heavy metals or of organic were present in these surrogate wastes. The
final spike concentrations used in the study were:
Arsenic - 10,000 mg/kg
Chromium VI - 10,000 mg.kg
Lead-10,000 mg/kg
Cesium-1,000 mg/kg
Strontium- 1,000 mg/kg
120
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E.3 POST-SPIKING ANALYSES OF THE SPIKED SOIL AND SLUDGE SAMPLES
Following spiking of all sample types, the following chemical and physical testing was
completed.
Dry screen, weight %
Cation exchange capacity
pH
Alkalinity
Atterberg limits
Moisture content
Unconfined compressive strength
Proctor compaction
Total concentrations of arsenic, chromium VI, lead, cesium, strontium
TCLP concentrations of arsenic, chromium VI, lead, cesium, strontium
Summaries of the procedures that have not already been summarized in Appendix D are provided
below.
Determination of Arsenic in Ores. Mill Products, and Mineral Processing Liquors by
Arsine Generation and Atomic Absorption Spectrophotometry - This method is designed to
determine the concentration of arsenic in solids and liquid samples. Arsenic concentrations from
0.5 parts per million in solids and 0.005 milligrams per liter in liquids up to 1 percent of the total
sample volume can be determined using this procedure. Samples first undergo an acid digestion.
An aliquot of the digestate is reacted with sodium borohydride and the resulting arsenic hydride
gas is then thermally decomposed to elemental arsenic. The concentration of arsenic is measured
using atomic absorption spectrophotometry. The presence of significant concentrations of
copper, cobalt, nickel, tellurium, tin, antimony, or bismuth may cause interferences. The method
includes procedures which will reportedly "partially" overcome such interferences.
Method 3500-Cr D. Colorimetric Method - This procedure is designed to determine the
concentration of hexavalent chromium colorimetrically. The reaction of hexavalent chromium
with diphenylcarbizide in an acid solution results in a red-violet colored solution and the
concentration determined based on the absorbtivity of the sample compared to a calibration
curve. The results are reported as milligrams per liter of hexavalent chromium. For total
chromium determinations, the sample is subjected to an acid digestion followed by oxidation
with potassium permanganate. While the potential for interference from several other metals
exist, the method includes additional treatment steps to alleviate such interferences.
Analysis of Ores and Mill Products by Atomic Absorption Spectrophotometry (Cd. Cu. Ag.
Pb. Mn. Ni. Zn. Co. Fe) - This method is designed to determine the concentration of the listed
metals in solids and liquid samples. Metal concentrations as low as 0.001 percent of each metal
can be determined using this procedure. Samples first undergo an acid digestion. An aliquot of
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the resulting digestate is analyzed using atomic absorption spectrophotometry to determine metal
concentrations. The presence of appreciable quantities of organic material or certain refractory
minerals may interfere with the accurate use of the method.
Analysis of Ores and Mill Products by Atomic Emission Spectrophotometer. Cesium - This
procedure is based on a modification of Hazen Research, Inc.'s method for Analysis of Ores and
Mill Products by Atomic Absorption Spectrophotometry for Alkali/Alkaline Earth Elements. In
both procedures, solid samples are subject to an acid digestion prior to analysis. For the cesium
determination, an aliquot of the digested sample is analyzed using flame atomic emission
spectrophotometry to determine the total cesium concentration. Cesium concentrations of 0.001
percent and higher can be detected using this procedure.
Strontium - Lil?B4p7 Fusion and ICP Measurement - This method is designed to determine
the concentration of strontium in a sample. The sample is mixed with lithium tetraborate
(Li|2B4O7) and fused in a muffle furnace. The resulting fused sample is then dissolved in an acid
solution. The strontium concentration in the resulting solution is determined using Inductively
Coupled Plasma (ICP) Emission Spectroscopy.
SW-846 Method 1311. Toxicity Characteristic Leaching Procedure - This sample preparation
method is designed to determine the mobility of certain regulated organic and inorganic analytes
present in waste samples. The method, used to determine if a waste stream is a RCRA waste due
to the toxicity characteristic, includes provisions for the preparation of liquid, solid and
multiphasic wastes. Solid waste, as well as the solid aliquot of multiphasic waste, are subjected
to particle size reduction, if necessary, and than extracted according to the procedure. The
extraction process and fluid are determined based on characteristics of the waste and the target
analytes, with special equipment required for the analysis of volatile compounds. Following
extraction, the resulting liquid (leachate) is filtered prior to analysis by a standard SW-846
method appropriate for the target analytes. Liquid waste, and the liquid components of
multiphasic materials, are filtered prior to analysis. The standard target analytes include volatile,
semivolatile, pesticide, herbicide and metal analytes, as listed in Table 1 of 40CFR 264.21.
Table E-l provides the post-spiking testing results for the four soil and sludge sample types, each
spiked with one of two metal solutions - anion or cation - yielding eight spiked sample types.
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Table E-l Post-Spiking Soil Analytical Results
PARAMETER
Dry Screen, wt %
Plus '/2 inch
Vz by !4 inch
% inch by 6 Mesh
Minus 6 Mesh
pH of 50% Solution (In
triplicate)
Alkalinity, %NaOH
(in triplicate)
Alkalinity, % CO3
(in triplicate)
Alkalinity, %HCO3 (in
triplicate)
CEC meg/lOOg
(in triplicate)
INEEL
SOIL A
SPIKE
INEEL
S01LB
SPIKE
1.34
12.77
15.21
70.68
7.76
7.68
7.73
<0.04
<0.04
<0.04
<0.14
<0.14
<0.14
2.11
1.07
0.99
31.9
31.1
32.0
1.13
14.50
13.56
70.81
7.44
7.51
7.58
<0.04
<0.04
<0.04
<0.14
<0.14
<0.14
0.14
<0.14
0.25
26.6
28.1
32.0
Atterberg limits
Liquid limit
Plastic limit
36.9
17.1
43.0
15.2
-' SRS:':-::-
SOIL A
SPIKE
0.00
5.88
3.78
90.34
8.29
8.18
8.28
<0.04
<0.04
<0.04
<0.14
<0.14
<0.14
0.56
0.65
0.71
15.9
15.6
15.0
;-::SRS
SOIL B
SPIKE
SYNTHETIC
SOIL A
SPIKE
SYNTHETIC
SOFLB
SPIKE
SYNTHETIC
SLUDGE A
SPIKE
0.00
5.28
3.64
91.08
4.28
4.25
4.24
O.04
<0.04
<0.04
<0.14
<0.14
<0.14
<0.14
<0.14
<0.14
2.5
2.4
2.0
0.00
9.82
29.94
60.24
7.68
7.50
7.44
O.04
<0.04
O.04
<0.14
<0.14
<0.14
0.62
0.59
0.82
22.8
18.6
19.0
0.84
2.51
4.69
91.96
5.52
5.18
5.20
<0.04
<0.04
<0.04
0.14
0.14
0.14
O.14
O.14
0.14
6.3
6.4
5.9
0.53
9.92
25.50
64.05
12.98
12.97
12.82
O.04
0.26
0.38
0.25
0.88
0.60
0.65
O.14
O.14
7.2
7.0
6.9
SYNTHETIC
SLUDGES
SPIKE
0.57
3.26
10.95
85.22
12.55
12.02
12.49
0.64
0.63
0.55
0.14
0.25
0.39
O.14O.14
<0.14
0.9
1.0
1.0
NP
NP
NP
NP
25.5
17.3
NP
NP
NP
NP
24.9
17.3
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Table E-l Post-Spiking Soil Analytical Results (Continued)
PARAMETER
Plasticity Index
Atterberg Class
Moisture content, %
INEEL
SOIL A
SPIKE
19.8
CL
18.2
INEEL
SOSLB
SPIKE
27.8
CL
20.4
SRS : :
SOIL A
SPIKE
NP
NP
10.9
:• -SHS/; ;
SOILB
SPIKE
NP
NP
7.8
SYNTHETIC
SOILA
SPIKE
8.2
CL
11.4
SVNTHETIC
SOILS
SPIKE
NP
NP
15.8
SYNTHETIC
SLUDGE A
SPIKE
NP
NP
20.1
SYNTHETIC
SLUDGE B
SPIKE
7.5
CL
10.4
Unconfined Compressive Strength
Total stress, PSF
Axial strain, %
Proctor compaction
Optimum moisture content,
%
Maximum dry density, pcf
Total metals, in sample, mg/kg
Arsenic (in triplicate)
(10,000 mg/kg spike)
Chrome (VI)
(in triplicate)
(10,000 mg/kg spike)
Lead (in triplicate)
(10,000 mg/kg spike)
Cesium (in triplicate)
(1,000 mg/kg spike)
3547
1.83
18.6
105.1
10,900
10,200
9,530
3,750
3,700
3,850
NA
NA
NA
NA
NA
NA
4561
2.04
21.2
102.8
166
1.77
10.9
120.0
NA
NA
NA
NA
NA
NA
10,800
10,600
10,800
370
510
610
10,400
10,300
10,600
4,100
4,090
3,890
NA
NA
NA
NA
NA
NA
299
2.00
7.9
123.6
2072
2.38
11.8
121.8
3478
1.39
16.4
114.2
2502
2.74
20.6
107.3
3572
2.82
10.7
123.8
NA
NA
NA
NA
NA
NA
9,810
9,570
9,410
490
440
520
12,200
10,700
12,100
4,570
4,560
4,430
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
10,200
10,500
10,000
530
620
410
11,300
11,400
9,360
5,170
5,380
5,120
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
10,400
9,950
10,100
210
490
550
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Table E-l Post-Spiking Soil Analytical Results {Continued)
PARAMETER
Strontium (in triplicate)
(1, 000 mg/kg spike)
INEEL:
SOIL A
SPIKE
NA
NA
NA
INEEL
SOILS
SPIKE
1100
1100
1100
SRS
SOIL A
SPIKE
NA
NA
NA
SRS
SOILS
SPIKE
900
800
800
SYNTHETIC
SOFIA
SPIKE
NA
NA
NA
SYNTHETIC
SOILS
SPIKE
900
900
900
SYNTHETIC
SLUDGE A
SPIKE
NA
NA
NA
SYNTHETIC
SLUDGE B
SPIKE
900
900
900
TCLP Extraction, mg/L
Arsenic (in triplicate)
(500 mg/kg max.)*
Chrome (VI)
(in triplicate)
(500 mg/kg max.)*
Lead (in triplicate)
(500 mg/kg max.)*
Cesium (in triplicate)
(50 mg/kg max.)*
Strontium (in triplicate)
(50 mg/kg max.)*
81.6
74.3
84.2
230
241
255
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
159
87
180
9
10
12
31.6
33.8
31.9
141
112
125
281
289
298
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
519
458
500
49
34
45
40.0
33.3
38.9
165
185
162
244
268
247
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
443
424
426
29
28
27
34.0
32.7
33.6
1.54
1.90
3.85
248
239
312
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
1
3
2
58
58
59
38.0
39.4
39.9
* Maximum possible TCLP concentration based on dilution of 20:1 in the TCLP test.
"A" and "B" spikes are for the anion and cation solution spikes, respectively.
CL = Lean clay
NP = Non-plastic
NA = Not analyzed
•U.S. GOVERNMENT PRINTING OFFICE: 2000-523-103-lte Prog
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