vyEPA
United States
Environmental Protection
Agency
Risk Reduction
Engineering Laboratory
Cincinnati OH 45268
Center for Environmental
Research Information
Cincinnati OH 45268
Technology Transfer
October 1989
CERI-89-222
Immobilization
Technology Seminar
Speaker Slide Copies and
Supporting Information
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IMMOBILIZATION TECHNOLOGY SEMINAR
Speaker Slide Copies and Supporting Information
October 1989
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Notice
The U.S. Environmental Protection Agency (EPA) strives to provide accurate, complete,
and useful information. However, neither EPA nor any person contributing to the
preparation of this document makes any warranty, expressed or implied, with respect to the
usefulness or effectiveness of any information, method, or process disclosed in this material.
Nor does EPA assume any liability for the use of, or for damages arising from the use of, any
information, methods, or process disclosed in this document.
Mention of trade names or commercial products does not constitute endorsement or
recommendation for use.
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TABLE OF CONTENTS
Section 1
Immobilization Processes Overview 1-1
Abstract 1-2
Slides 1-12
Section 2
Descriptions of Solidification and
Stabilization (S/S) Technologies 2-1
Abstract 2-2
Slides 2-12
Section 3
Description of Vitrification Technology 3-1
Abstract 3-2
Slides 3-8
Section 4
Physical Testing Methods for Determining
Effectiveness of S/S Processes 4-1
Abstract 4-2
Slides 4-5
Section 5
Chemical Testing Methods for Determining
Effectiveness of S/S Processes 5-1
Abstract 5-2
Slides 5-6
Section 6
Technology Screening Procedures for
Determining if S/S Should be Implemented 6-1
Abstract 6-2
Slides 6-4
Section 7
Field Implementation Procedures Utilized for S/S 7-1
Abstract 7-2
Slides 7-6
Section 8
Quality Assurance Procedures for Ensuring
Long-Term Performance 8-1
Abstract 8-2
Slides 8-5
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IMMOBILIZATION PROCESSES
OVERVIEW
SECTION 1
Abstract 1-2
Slides 1-12
1-1
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IMMOBILIZATION PROCESSES OVERVIEW
Mr. Carl ton Wiles Mr. Edwin Earth
USEPA/RREL USEPA/RREL
Cincinnati, Ohio Cincinnati, Ohio
Solidification/stabilization technology is being utilized as a treatment
technology for Resource Conservation and Recovery Act RCRA listed waste and
waste from uncontrolled hazardous waste sites. Several Best Demonstrated
Available Technology (BOAT) levels for Resource Conservation and Recovery
Act (RCRA) waste codes are based on solidification/stabilization
technology. Vitrification technology is emerging as an alternative
technology for hazardous waste. Approximately 25 percent of the Records of
Decision (RODs) for Fiscal Year 1988 for the Superfund Program involved
solidification/stabilization.
REFERENCES
Barth, E.F., Wiles, C., Technical and Regulatory Status of
Solidification/Stabilization in the United States. Proceedings on the
Application of U.S. Control Technology in Korea, Seoul, Korea (1989).
U.S. EPA Guide to the Disposal of Chemically Stabilized and Solidified
Waste, SW-872 (September, 1980)
U.S. EPA Handbook for Stabilization/Solidification of Hazardous Waste, EPA
540/2-86/001 (June, 1986).
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TECHNICAL AND REGULATORY STATUS OF
SOLIDIFICATION/STABILIZATION IN THE UNITED STATES
E. F. Barth and C. C. Wiles
U.S. Environmental Protection Agency
Cincinnati, Ohio USA
1.0 INTRODUCTION
Solidification/stabilization (S/S) technology has been used for over
20 years to treat U.S. industrial waste and more recently for contaminated
soils and municipal waste combustion residuals.
1.1 SOLIDIFICATION/STABILIZATION TECHNOLOGY
1.1.1 Definitions
Definitions for S/S technology vary depending upon the source. Other
terms that have been used are immobilization and fixation. In very general
terms, S/S, as it relates to managing hazardous waste, refers to a
technology where one uses additives or processes to transform the waste into
a more manageable form or less toxic form by physically and/or chemically
immobilizing the waste constituents. It is important to understand the
terminology being used in order to properly evaluate the technology for
potential application.
1.1.2 Objectives
The broad objective of S/S technology is to contain a waste contaminant
and prevent or minimize the release of the contaminant into the
environment. In practice this broad objective may be realized by several
mechanisms which include producing a solid; improving the handling
characteristics of the waste; decreasing the surface area across which the
transport of the contaminant may occur; and limiting the mobility of the
contaminant when exposed to leaching fluids. The ideal objective is to
chemically transform or bond the toxic contaminant into a non-toxic form.
Realistically, chemical bonding of the binder to the contaminant does not
routinely occur with available state-of-the-art inorganic S/S technologies.
More vendors, however, are claiming that chemical bonding from additive
reagents does take place, rather than or in addition to microencapsulation.
1.1.3 Binders and Binding Mechanisms
Binder systems can be placed into two broad categories, inorganic or
organic. Most inorganic binding systems in use include varying combinations
of hydraulic cements, lime, pozzolans, gypsum, and silicates. Organic
binders used or experimented with include epoxy, polyesters, asphalt/
bitumen, polyolefins (primarily polyethylene and polybutadiene), and urea
formaldehyde. Combinations of inorganic and organic binder systems have
been used. These include diatomaceous earth with cement and polystyrene;
polyurethane and cement, polymer gels with silicate and lime cement and
organic modified clays.
1-3
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1.1.4 Process Types
S/S process types normally found in the U.S. are: in-drum processing,
in-plant processing, mobile plant processing, and in-situ processing.
Combinations of these process types may be used depending upon specific
requirements at a given site. In the case of a contaminated soil area,
in-situ and mobile type of processes are most often used.
1.2 Current Status of S/S in the U.S.
Although S/S has seen significant use for treating industrial waste in
the U.S., there are technical and regulatory factors which may greatly
affect its future use. U.S. EPA regulations and proposed regulations
controlling the treatment and disposal of hazardous waste and contaminated
soil and debris will be the major factor determining how much S/S technology
will be used. The remaining portions of this paper will further discuss the
U.S. EPA S/S programs and the factors important in determining how much S/S
will be used in the future in the U.S.
2.0 THE U.S. EPA PROGRAM IN SOLIDIFICATION/STABILIZATION
The U.S. EPA programs in S/S include evaluating S/S as a best
demonstrated available technology for treating hazardous waste, evaluating
S/S for treating contaminated soil and debris, as well as municipal waste
combustion residuals and conducting research to develop a more comprehensive
scientific understanding of the technology.
2.1 RESEARCH
The current U.S. EPA research (Table I) has emphasized investigating
interferences to S/S, investigating waste-binder interaction and waste
disposition sites, and study of methods for predicting performance of S/S
products.
2.1.1 Interfering Agents
Research on interfering agents will produce data on the effects that
interfering inorganics (certain metals, sulfates, etc.) and organics (oil,
grease, HCB, TCE, phenol, etc.) may have on generally used pozzolanic binder
systems. The information will be useful in evaluating applications for
deli sting hazardous waste and for permits to treat hazardous wastes with
S/S, particularly for those waste streams contaminated with organics. This
information and that from research on factors critical to S/S will also aid
decisions on potential waste pretreatment techniques for enhancing S/S
performance. Data from physical and chemical tests are being analyzed to
determine if a correlation exists between physical properties of the
solidified waste form and its ability to resist stresses when exposed to
leaching situations. An extensive literature search on interference
compounds and interference testing has been completed (2,3).
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2.1.2 Evaluating Test Methods
An effort with Environmental Canada is emphasizing evaluation of
several leaching tests for determining the extent of toxic constituent
binding. Protocols for examining physical properties are also being
evaluated. This research includes actual waste and synthetic sludges
solidified by vendors. Information on the performance of several different
solidified products can be compared. This research will provide important
data to compare current U.S. EPA regulatory leaching procedures with others
beign tested. However, more research is needed to determine the long-term
effectiveness of this treatment technology.
2.1.3 Morphological Studies
Electron scanning and x-ray diffraction microscopy techniques and
solvent extractions are being used to investigate waste/binder
interactions. The objective is to better understand S/S by identifying
binder reaction phases where the waste from other research projects are
being examined in efforts to correlate results of physical and chemical
tests with performance of S/S products. Results from these specific studies
have indicated that physical entrapment of inorganic metals is a predominant
containment mechanism (4). However, some results are also indicating
formation of altered or new crystal structures in some phases which appear
to be chemically bonding some organics. Indications are that this type
research could provide information useful in preparing binder formulations
better able to treat a specific waste.
2.1.4 Air Emissions
Because of the nature of many solidification processes, uncontrolled
air emissions are a potential problem to workers and the environment.
Investigations are being conducted to determine the magnitude of these air
emissions (5, 6). Processes being evaluated are Portland cement - fly ash
and lime kiln dust - fly ash mixtures. As expected, mixing causes the
greatest air emissions. Some additives such as lime result in exothermic
reactions which increases the release of volatile compounds or may cause
combustion. Capture and treatment of these emissions may be required to
protect worker health and the environment, particularly in cases where the
waste or contaminated soils contain volatile compounds.
2.2 EVALUATION OF S/S AS AN AVAILABLE TREATMENT TECHNOLOGY
2.2.1 Treatment of Hazardous Wastes
In the United States, the Hazardous and Solid Waste Amendments (HSWA),
which amended the Resource Conservation and Recovery Act (RCRA) provide
detailed procedures dictating how hazardous waste is defined, controlled,
and managed. Wastes classified as hazardous under RCRA are often referred
to as RCRA hazardous waste. Key provisions of HSWA are the ones which ban
1-5
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the land disposal of hazardous waste unless it is proven to be more
protective of the environment and human health than other alternatives. The
legislation requires that all hazardous waste be treated by the best
demonstrated available treatment (BOAT) instead of and prior to land
disposal. The U.S. EPA is required to determine and specify levels to which
BOAT technologies can treat RCRA waste. S/S is one of several BOAT
technologies being evaluated for non-waste waters (see Table II). In this
program selected hazardous wastes are solidified/stabilized by portland
cement, lime kiln dust, and lime/fly ash mixtures. Various ratios of waste
to binder for each binder system is then evaluated by the Unconfined
Compressive Strength Test (UCS) after a cure time of 7, 14, 21 and 28 days.
Cured samples are then subjected to the U.S. EPA's Toxicity Characteristics
Leaching Procedure (TCLP) extraction test. Leachate from the TCLP is
analyzed for the pollutants of concern, to determine how effective S/S can
be for treating the selected hazardous waste. Results will be important in
determining how much S/S will be used to treat hazardous waste in the U.S.
2.2.2 Treatment of Contaminated Soils
The remediation of contaminated soils from uncontrolled dump sites, is
controlled under legislation referred to as the Superfund Amendments and
Reauthorization Act (SARA) which amended the Comprehensive Environmental
Reclamation Compensation Liability Act (CERCLA). Under SARA provisions,
permanent treatment of the contaminated soil and debris is being emphasized
rather than the use of nontreatment containment systems such as covers,
grout walls, and similar methods. Because of this, a program similar to the
RCRA BOAT evaluations is being conducted for SARA remediation technologies
including S/S. Mixtures of soils contaminated with selected chemicals were
solidified/stabilized and tested to evaluate performance of S/S technology
for treating contaminated soils. The test soil being used is a mixture of
clay, sand, silt, topsoil and aggregate. As can be seen from Table III,
solidification/stabilization was effective for reducing the leaching
concentrations of arsenic, copper, lead, nickel, and zinc. No conclusion
could be made from the chromium data since the initial concentrations were
low.
2.3 SUPERFUND INNOVATIVE TECHNOLOGY EVALUATIONS (SITE)
The U.S. EPA SITE Program provides for demonstration and evaluation of
innovative technologies to remediate Superfund sites. Currently six S/S
processes are being evaluated (Table IV). The vendors are allowed access to
the sites and pay for their operational and treatment expense. The U.S. EPA
pays for site preparation work and sampling and analytical cost. Results
will provide information on how well S/S can be expected to permanently
treat contaminated soils. The evaluations will also help make better
extrapolation of laboratory tests results to field conditions.
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3.0 PROCESS SELECTION CONSIDERATIONS
3.1 IMPORTANT FACTORS
Factors Important in the selection, design, implementation, and
performance of processes and products are: waste characteristics (chemical
and physical), processing requirements, S/S product management objective,
regulatory requirements, and economics. These and other site-specific
factors (i.e., location, condition, climate, hydrology, etc.) must be
carefully considered to ensure acceptable performance.
3.1.1 Haste Characteristics
The chemical effects of some compounds can reduce the strength of the
binder/waste mix, while some compounds can accelerate or retard the S/S
curing rate. Temperature and humidity can also retard or accelerate
curing. Size and shape of particles can affect the viscosity of the mix.
The impact of strength on Teachability has not been determined.
3.1.2 Process Type/Quality Assurance and Control
It is important to assess what process type and specific process
requirements are required before selecting an S/S technology. For example,
a waste-binder can be controlled and mixed more easily in a drum or in a
plant process than in the in-situ solidification of a pit, pond, or lagoon.
The performance of a process is related to the extent of mixing. More
techniques are needed to determine mixing effectiveness. An effective real
time Quality Assurance/Quality Control program may need to focus on indirect
monitoring techniques (metering equipment, reagent quality and pilot test
cells, operator experience, etc.) with then on-line sampling.
3.1.3 Treatment Objectives
The performance goals of the process must be established, for example,
strength or leachate reduction required. The ultimate disposal condition
must also be determined.
3.1.4 Regulatory Factors
Hazardous waste management regulations in the United States will be
critical to the success of S/S. Processes can be altered to meet different
performance criteria, which will become increasingly stringent, as
regulations become more stringent. S/S will be competing with other
treatment technologies to meet these regulatory criteria.
3.1.5. Costs
Costs will depend on site-specific conditions. Important are the
waste's characteristics, type of process, disposal requirements and other
special factors. What is the physical form and chemical make-up of the
waste? Is pretreatment needed? Is transportation of raw materials and/or
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are finished S/S products required? Which S/S process is needed? What
special health and safety requirements are needed? What is the quality
assurance/quality control cost involved? What regulatory criteria must be
met? Each of these factors must be considered. As regulatory criteria
become more demanding, the costs of acceptable solidification processes may
increase.
4.0 STUDIES NEEDED FOR S/S AS A TREATMENT TECHNOLOGY
For S/S technology to be effective in managing hazardous waste,
proposed processes must be properly selected, formulated, and used.
Improved knowledge of process selection considerations and the interactions
among the various candidate binders and waste types is critical to the
successful use as an acceptable treatment technology.
Studies are needed:
to determine the long-term physical-chemical stability of S/S
products when placed on the land;
to determine how and under what conditions S/S products should be
placed on the land to ensure long-term environmental protection;
to more accurately predict and measure the performance of S/S
processes and products;
to provide a correlation between regulatory criteria and real
world situations;
to evaluate the effectiveness of protocols (e.g., leaching tests,
durability test, etc.) to characterize S/S products, provide
effective measurement techniques, and correlate results of such
tests with performance in the field;
to determine if micro-encapsulation is an effective technique
without bonding;
to determine the effectiveness of processes and equipment to
effectively solidify/stabilize contaminated soil and/or lagoons;
the effectiveness of mixing methods; and the resulting
solidified/stabilized soil performance at varying soil depths;
to determine the amounts of organic compounds that can be included
in inorganic waste streams without requiring pretreatment before
S/S;
to determine how effectively S/S processes treat residuals from
other alternative treatments.
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5.0 SUMMARY
Solidification/stabilization is being evaluated by the U.S. EPA as a
best demonstrated available technology for treating hazardous waste and
contaminated soils and debris. Future use of the technology in the United
States will depend on how well it performs compared to other available
treatment processes. The evaluations and current research being conducted
will provide some answers regarding performance, however, additional studies
are required for a better scientific understanding of S/S. Whether or not
S/S becomes an important technology for treating hazardous waste and
contaminated soils in the U.S. ultimately depends upon regulatory
requirements and the capability of the technology to meet these
requirements. As performance criteria become more severe, S/S developers
may need to improve their processes. The future technology direction is
showing progress. In the case of RCRA waste, S/S may be the only acceptable
method to treat selected inorganic waste and hazardous residues from
incinerators and other treatment processes. In the case of contaminated
soils and debris, S/S offers a relatively inexpensive method for treating
large areas in situ. However, the capability of the technology to perform
satisfactorily over long periods of time has yet to be determined.
REFERENCES
1. Wiles, C. C: A review of Solidification/Stabilization Technology.
Journal of Hazardous Materials. Vol. 14, (1987)
2. Jones, L. W: Interference Mechanisms in Waste
Solidification/Stabilization Processes, Final Report for U.S. EPA. IAG
No. SW-219306080-01-0 (1988)
3. Cullinane, M. J: An Assessment of Materials that Interfere With
Solidification/Stabilization Processes. Final Report for U.S. EPA. IAG
No. DW-219306080-01-0 (1988)
4. Cartledge, F, K., et.al.: A Study of the Morphology and Microchemistry
of Solidified/Stabilized Hazardous Waste Systems. Final Report for U.S.
EPA #CR-812318 (1989)
5. Weitzman, L., Hammel, M., and Barth, E: Evaluation of
Solidification/Stabilization as a BOAT for Contaminated Soils,
Proceedings of Fourteenth Annual HWERL Symposium, Cincinnati, OH (1988)
6. Weitzman, L. et.al.: Volatile Organic Emissions from Stabilized
Hazardous Waste. Final Report. U.S. EPA Contract #68-02-3994 (1989)
1-9
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Table I. CURRENT U.S. EPA SOLIDIFICATION/STABILIZATION
RESEARCH PROJECTS
Project Title
Objective
Evaluation of S/S for Treating
Ash Residues, Hazardous Sludges,
and Contaminated Soils
Evaluation of Factors Affecting
Solidification/Stabilization Process
Investigation of Comparative Test Methods
for Solidified - Waste Characterization
Study of Morphology and Microchemistry
of Solidified/Stabilized Waste
Air Emissions from Waste Stabilization
Use of S/S in Treatment Train
Potential Use of Organophilic Clays
and Other Organic Binders
Construction Quality Assurance/
Quality Control Parameters
Evaluate efficacy for treating
several waste types from each
category
Determine effects of interfering
agents on performance of S/S
Develop and evaluate methods for
testing performance of solidification
processes
Investigate bonding mechanisms
Determine air emissions from S/S
processes
Determine efficacy of S/S following
incineration, low temperature
desorption, and soil washing
Determine treatment potential of organic
binders
Development of QA/QC procedures for
real time field use
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TABLE II. EXAMPLE OF U.S. EPA RCRA HAZARDOUS WASTES FOR WHICH
S/S IS BEING EVALUATED AS A TREATMENT TECHNOLOGY
Waste Code Description of Waste Pollutant of Concern for S/S_
K048-52 Dissolved air flotation (DAF) float chromium, lead
from the petroleum refining Industry
K061 Emission control dust/sludge from the chromium, lead, cadmium
primary production of steel 1n
electric furnaces
K046 Wastewater treatment sludges from lead
manufacturing formulation and
loading of lead-based Initiating
compounds
F006 Metal finishing sludges cadmium, chromium, lead,
nickel, silver
F012, F019 Metal finishing sludges cadmium, chromium lead,
nickel, silver
K022
K001
Metal
As
Cd
Cr
Cu
Pb
Ni
Zn
Distillation tar (treated) chromium, nickel
Wood preserving sludges (treated) lead
TABLE III. CONTAMINATED SOIL (SARM) TCLP RESULTS
FROM U.S. EPA SARA BOAT STUDY
Raw
6.4, 9.6
33.1, 35.3
No, .06
80.7, 10.0
19.9, 70.4
17.5, 26.8
359, 396
(mg/1)
Treated
ND, ND
ND, ND
.07, .07
.09, .17
ND, .37
ND, ND
.69, .74
Source of data: Weitzman, Hammel, Barth (5)
TABLE IV. SOLIDIFICATION/STABILIZATION PROCESSES BEING
EVALUATED IN THE U.S. EPA SITE PROGRAM
Chemfix Technologies, Inc.
Soliditech, Inc.
Silicate Technology, Inc.
Hazcon, Inc.
International Waste Technologies
Separation and Recovery Systems
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OVERVIEW OF SEMINAR
Introduction
Descriptions of S/S technologies
Description of vitrification technology
Technology screening procedures
Physical testing methods
Chemical testing methods
Field implementation procedures
Quality assurance procedures
Case histories
OVERVIEW OF INTRODUCTION SECTION
Definitions
Range of immobilization technologies
Process descriptions
Where being utilized
Regulations
IMMOBILIZATION TECHNOLOGIES
Solidification
Stabilization
Vitrification
Other
Macroencapsulation
Microencapsulation
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SOLIDIFICATION
VS.
STABILIZATION
HIERARCHY OF HAZARDOUS WASTE
MANAGEMENT
Waste minimization/reduction
3-R's
- recovery
- reuse
- recycle
Treatment
- destruction
- reduction
mobility, toxicity. volume
Storage
GOALS OF S/S PROCESSES
Reduce pollutant mobility
Decrease surface area (reduce loss or
transfer of contained pollutants)
Produce solid with no free liquid
Improve handling and physical
characteristics of waste
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WHY CONSIDER S/S?
Minimizes leachate rate from metal waste
Lower cost than other immobilization
technologies, especially if done in situ
TREATMENT TRAIN
SOIL WASHING FOLLOWED BY S/S
SOL
+2mm
PUG Mil
TREATMENT TRAIN
THERMAL DESORPTION FOLLOWED BY S/S
SOIL
PUG MILL
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TREATMENT TRAIN
INCINERATION FOLLOWED BY S/S
SOL
PUG MILL
CURRENT STATUS OF S/S UTILIZATION
IN U.S.A.
25% of Superfund sites in FY 1988
Several RCRA waste codes for BOAT
Being considered for MWC ashes
EXAMPLES OF U. S. EPA RCRA HAZARDOUS
WASTES FOR WHICH S/S IS BEING
EVALUATED AS A TREATMENT TECHNOLOGY
Wast*
Cod*
Description
of Wast*
'Pollutant
of Cono*rn for S/S
K048-62 Dissolved air flotation (DAF) chromium, l*ad
float from th* p*trol*um
r*flnlng Industry
K061 Emission control dust/sludg* chromium, lead
from th* primary production cadmium
of st**l In *l*ctrlc furnaot
K046' Wast*watซr trซatm*nt sludg*s l*ad
from manufacturing formulation
and loading of l*ad-bas*d
Initiating compounds
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EXAMPLES OF U. S. EPA RCRA HAZARDOUS
WASTES FOR WHICH S/S IS BEING
EVALUATED AS A TREATMENT TECHNOLOGY
(continued)
Waste
Code
Description
of Waste
Pollutant
of Concern for S/S
F006
Metal finishing sludges
F012, F019 Metal finishing sludges
K022
K001
Distillation tar (treated)
Wood preserving sludges
(treated)
cadmium, chromium,
lead, nickel, silver
cadmium, chromium,
lead, nickel, silver
chromium, nickel
lead
CURRENT STATUS OF S/S UTILIZATION
FOR RADIOACTIVE SITES
NRC has guidance for
low level disposal
SITE PROGRAM
DEMONSTRATIONS
HAZCON
IWT
SOLIDITECH
CHEMFIX
STC
SRS
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INSTITUTIONAL CONSIDERATIONS
Waste is neither destroyed nor
altered unless volatilized
Rate of release to groundwater
is minimized, but "no migration"?
Air pathway minimized
Volume increase
RE -USE /RECLAMATION
ISSUES
Will there be direct contact?
Will there be rain contact, ocean
contact, or groundwater contact?
What will applied load be?
CHEMICAL REACTION
MECHANISMS
Precipitation as;
- hydroxides (OH)
- silicates (Si)
- sulfides (S)
Complexation
Organic binding
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BINDING AGENTS
Inorganic
Organic
Combination
BINDER MATERIAL UTILIZED FOR S/S
Inorganic
Cement
Lime
Kiln dust
Fly ash
Silicates
Clay
Zeolite
BINDER MATERIAL UTILIZED
FOR S/S
Organic
Asphalt
Surfactant
Modified clay
Activated carbon
Polyesters
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BINDER MATERIAL UTILIZED
FOR S/S
Organic
(continued)
Polyethylene
Resin
Epoxide
Urea formaldehyde
SUMMARY
Process Type
Cement
Pozzolanic
Asphaltic
Thermoplastic
Organic Polymer
Macroencapeulatlon
Other
Total
OF 1986 TSDF
No. Units
50
37
1
0
1
3
15.
107
Quantity (tons')
281,596
391,635
0
0
157
306
4.110
658,104
SURVEY
Capacity (tons)
9,660,805
2,111,111
100,000
0
157
2,826
11.247
6,106,346
REGULATIONS
RCRA/HSWA
CERCLA/SARA
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GOALS OF S/S TREATMENT
Delist
BOAT
Subtitle D
Subtitle C
HAZARDOUS WASTE MANAGEMENT
REGULATIONS
RCRA
- no free liquids
- 50 p.s.i.
- liquids - Release Test
HSWA
- BOAT
UNCONTROLLED HAZARDOUS WASTE SITE
REGULATIONS
CERCLA
- cost effective remedy
SARA
- treatment preference
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S/S CONSIDERATION AS A
REMEDIAL TECHNOLOGY
Treatment by S/S can achieve
substantial reduction of mobility
S/S treatment may represent
the best balancing of the
selection criteria (including low
level organics)
Management considerations
COST ESTIMATION
Mobilization $100.000-200.000/site
Excavation $10-50/cy
Processing $50-100/cy
Disposal $100-250/cy
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DESCRIPTIONS OF
SOLIDIFICATION AND STABILIZATION
(S/S) TECHNOLOGIES
SECTION 2
Abstract 2-2
Slides 2-12
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DESCRIPTIONS OF SOLIDIFICATION/STABILIZATION TECHNOLOGIES
Dr. Leo Weitzman Mr. Jesse Conner
l_vw Chemical Waste Management
Durham, North Carolina Riverdale, Illinois
1.0 INTRODUCTION
As a result of the 1984 RCRA amendments, no liquids and only limited
amounts of chemical wastes may be placed in hazardous waste landfills without
being chemically altered prior to disposal. This ruling has resulted in
increased quantities of waste being solidified or stabilized. This paper
gives a brief description of the S/S industry and the processes that are used.
"Solidification/Stabilization" (S/S), also referred to as waste fixation,
is a relatively simple process. The waste is mixed with a binder or mixture
of binders. The mass is then cured to form a solid matrix that can be safely
disposed in a landfill or other containment.
While solidification and stabilization are mechanically very similar,
they are really two different industries. Solidification is the traditional
industry which takes a waste that contains free water and solidifies it by
reacting it with a binder such as cement or lime. No effort is made to reduce
the Teachability of any hazardous constituents that may be present in the
waste. The goal is only to react all free liquids in the waste with the
binder. The stabilization industry is emerging in response to the recent
"Land Ban" regulations which are restricting specific categories of waste from
hazardous waste landfills unless they are pretreated to a minimum Teachability
standard. Wastes are stabilized by mixing them with specific types and,
usually larger quantities, of binder to fix the hazardous constituents in the
solid matrix. The intent in this case is to reduce the Teachability of
hazardous constituents as measured by the Toxicity Characteristic Leaching
Procedure (TCLP).
It is important to differentiate between these two unique industries when
evaluating the industries and assessing the impact that regulations will have
on them. The initial restrictions on the landfill disposal wastes containing
free liquids created the solidification industry. Until this ban, very few
wastes were treated in this way prior to disposal. Such treatment can be
achieved by the addition of relatively small amounts of binder which converts
the waste into a soft granular solid. Such a solid can be readily loaded onto
bulk carriers and shipped to a landfill for disposal.
Now, the "Land Ban" restrictions are requiring that more types of waste
be treated beyond the point of just chemically binding with free liquids. The
treatment must also immobilize contaminants. Such treatment usually requires
the addition of more binder and often (but not always) produces a hard,
monolithic solid mass that is analogous to soft concrete. Handling such a
mass is much like handling large, irregularly shaped concrete chunks which
cost more to transport than does the original waste. As a result, facilities
that are close to hazardous waste landfills are in a better position to
stabilize wastes than are those that have to ship the treated waste.
2-2
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For the purpose of determining and minimizing organic air emissions, the
S/S process can be broken down into three distinct steps:
1. mixing
2. curing
3. storage and landfill ing
The mixing step is the basic operation where the waste is placed into a
mixer and combined with the binder. The mixer is normally designed for ease
of loading of the waste and binder and removal of the mixed material. Once
mixed, the material is allowed to cure, at which time chemical reactions
between the waste and binder harden the mixture. Curing can take place in the
mixing vessel (as when mixing occurs in a drum or other disposable vessel) a
temporary storage area, or directly in the landfill where the waste is
ultimately placed. It can take as little as a few hours to as 30 days or more.
The final step, storage and disposal, is the goal of the S/S process.
The material has hardened and if the binders are appropriate for the
application, the waste has been stabilized. At this point, the material may
be placed in a landfill and covered.
Until relatively recently, the mixing of wastes and binder has been done
in open pits, trenches and bunkers. These do not lend themselves to proper
collection and control of air emissions. S/S processes can and do produce
both particulate and organic air emissions. Particulate control is being
required with increasing frequency by states and by federal regulations.
Organic emissions from these processes will soon be regulated on a national
level by EPA.
Generally speaking, the type of mixing equipment used will influence how
well the organic air emissions are collected and controlled, and the type of
binder used will influence the point in the process where they will be
released. The mixing equipment's effect on emissions is illustrated by the
two extremes of a completely open and a completely closed mixing system.
Emissions from a completely open mixing system, an open-pit mixer for example,
can be complex, requiring the installation of large enclosures. The
enclosures need to be designed so that the waste and binder can readily be
added to the mixing vessel, or pit, and the mixture can be removed as well.
By comparison, it is relatively easy to duct an enclosed mixer to an air
pollution control device. In either case, once the Organic Air Emissions are
collected, their removal or destruction can be achieved using readily
available equipment.
The type of binder used, determines the temperature of the system during
mixing or curing. For example, a binder, based on quicklime (CaO), will get
very hot when mixed with an aqueous waste. The high temperature will cause a
rapid release of the organic constituents. Because the solidified/stabilized
product will then have lost most of the volatile constituents during mixing,
it will release fewer organic air emissions during curing, storage, and
disposal. If the mixing must occur in open equipment, then a binder with a
low heat release is desirable. This will result in minimizing the organic air
release until the waste can be placed in a sealed and capped landfill.
2-3
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Clearly, in order to control air emissions during mixing it is necessary
to capture them while mixing is going on and during the handling of the waste
before and after mixing. If a greater degree of control is required it may be
necessary to capture the emissions during the curing phase as well. Control
of organic air emissions, once captured, is straightforward. Standard
technologies such as condensation, adsorption, thermal incineration, or
catalytic incineration can be used to collect or destroy the organic air
emissions captured. Particulate emissions control, while straightforward,
does require special consideration since the particulate is wet and includes
cement or other natural or synthetic pozzolans which can clog and damage the
collection equipment.
The following sections discuss the types of mixing equipment and binders
commonly used in commercial S/S processes.
2.0 STABILIZATION PROCESS DESCRIPTION
The various stabilization processes commonly used are described in detail
by Cullinane and Jones (5). The following discussion is designed merely to
offer an overview of the steps involved. S/S can be broken down into two
components. The first is the type of process used to mix and handle the
wastes and binders, and the second is the type of binder used. With very few
exceptions, each mixing method can be used for each type of binder. The
exceptions are discussed in Section 4.
2.1 PROCESS TYPES
2.1.1 Open Pit or Trench Mixing
This is the simplest and most commonly used S/S process. The waste is
placed in a lined trench, lagoon, or pit, and the binder is mixed with it.
Most frequently, a backhoe or a similar device is used to mix the waste and
binder. This process is frequently used to S/S waste or soil at field
remediation as well as at permanent locations.
S/S is often used in field remediation to solidify a pond or lagoon in
place. The binders are then simply dumped into the pond or lagoon and a
backhoe is used to blend them in. The solidified material may then be either
left in place and capped or excavated and landfilled elsewhere.
When open trench mixing is used at a fixed location, as in a treatment
facility, it is typically performed in a lined trench made of concrete. The
trench is sometimes placed in a large, open building to protect it from the
elements and can be above or below grade. Truckloads or drumloads of the
waste are emptied into the trench and the binder is added, either with a
backhoe, front-end loader or through a bulk solids handling system. The mass
is then mixed with either a backhoe arm or with the blade of the front-end
loader. When the front-end loader is used, the mixing is performed by
kneading the waste and binder against the wall of the trench. After the
2-4
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mass 1s mixed, the backhoe or front-end loader 1s used to load the pasty mass
Into a truck or roll-off container for transport. The mixture 1s then,
typically taken to a storage area for curing or to the landfill Itself.
After the mass hardens, usually within one day, 1t 1s tested Of required
by regulations) and, 1f It satisfies the regulations, It 1s landfllled.
2.1.2 In-S1tu S/S(Egg Beater Mixing)
This process 1s a recent development 1n which soil 1s mixed with the
binder In-place, without excavation. A mobile process Is used that combines
several drills with bits up to six feet In diameter on one truck or trailer.
The process literally drills down Into the contaminated soil and as the drill
penetrates 1t, binder 1s Injected. The drill mixes the binder and soil. If
emission control Is needed, a shroud fits over the drilling assembly.
2.1.3 In-Drum Processing
This 1s a small-scale process 1n which the binder and waste are mixed In
a drum or other disposable container. An open-head drum with a standard drum
mixer mounted 1n It Is typically used for this application. After mixing, the
mixer Is removed and waste-binder matrix allowed to set. The lid 1s put on
the drum and the waste, drum and all, Is disposed of 1n a landfill.
2.1.4 Reactor Processing
This process Is a simple scale-up of the 1n-drum processing system. The
bulk waste material and binder are mixed In mechanical mixing vessels. The
vessel can be either open or closed top and should have provisions for loading
and discharging the solids and waste.
2.1.5 Batch and Continuous Type Closed-Vessel Processing
This process is similar to Reactor Processing with the exception that the
reactor 1s totally enclosed to facilitate collection of the air emissions
during mixing. The reactor will generally be purged with a controlled air
flow or, if the organic can form an explosive mixture, an inert gas such as
nitrogen. The mixing vessel can be a simple closed reactor with facilities
for loading and discharging solids or a continuous mixer such as a ribbon
mixer or pug mill.
2.1.6 Mobile Plant Processing
Any of the processes can be mounted on a trailer or truck and operated in
the field. The vapor collection and control equipment, if needed, would also
have to be mobile. The concepts for mobile plant processing are identical to
those for similar fixed systems and does not need to be discussed separately.
2-5
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2.2 SOLIDIFICATION/STABILIZATION AGENTS
In order for S/S to be effective, the binder used must:
a. React with free water in the waste and form a solid.
b. Bind with the metals and organics to reduce their chemical nature
and/or their Teachability.
c. Bind with the Organic Air Emissions in the waste to reduce their
chemical nature and ability to vaporize.
Ideally, the chemical processes used should involve chemical reactions
with the hazardous components in the waste; however, practically, this does
not happen very often for all components. Frequently, the binder reacts with
the free water and metals in the waste and the resultant matrix traps the
organic constituents so that they cannot be readily released. Laboratory
tests (1,3) have shown that while the typical inorganic processes appear to
immobilize the metals well, they do not reduce the emissions of the volatile
organic compounds significantly. Many simply absorb or absorb the free liquid
without reacting with it.
Sorption is often used as a means of solidifying wastes. It is not, by
itself, considered to be a stabilization process since it does not meet the
criterion that free water must be chemically combined into a solid matrix.
Sorption is frequently used to clean up hazardous materials spills. The
inorganic sorbents are sometimes used when the waste is a free flowing liquid
to make it easier to handle. In this case, the absorbent and waste would then
be stabilized by mixing it with other agents such as cement to make a solid.
Common absorbents are expanded clay and treated organic materials such as
corn-cobs, or simple sawdust. Organic sorbents are generally used to collect
liquids when the product will be sent to an incinerator for disposal.
Binders fall into two categories, inorganic and organic. They are also
identified by their chemical mechanism. By far, the most commonly used
binders are inorganics such as cement kiln dust, flyash, and other waste
materials that can chemically react with water. Because of the large amounts
of binder that are often required to solidify/stabilize a waste, cost of the
raw materials dominates the selection process. With development of new
regulations, leaching and organic air emissions, the binder's performance
will, probably, assume greater significance.
The vast majority of commercial S/S is performed with inorganic binders.
While a number of organic binders have been proposed, and marketed, their
performance has not been fully demonstrated to date. This coupled with their
high cost have kept them from making significant inroads into the market.
Within both categories, a variety of proprietary binders have been proposed or
are marketed by vendors. The majority of the wastes solidified at present
uses generic binders discussed below.
Table 2-1 lists some of the proprietary binders presently available. As
can be seen most are sufficiently similar to generic ones that their behavior
regarding organic air emissions can be readily determined from the discussions
below which restrict themselves to generic binders.
2-6
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2.2.1 Inorganic Binders
As
be
As mentioned earlier, binder is typically selected on the basis of cost.
a result, whenever, possible, a waste material that reacts with water will
used. Commonly used inorganic binders are:
cement kiln dust
lime kiln dusttypically contains
coal fly/bottom ash
mixtures of the above
significant amounts of quicklime
When these are unavailable or unsuitable,
These include:
commercial products are used.
natural pozzolans
lime (usually a grade of agricultural lime) mixed with flyash
Portland cement, usually mixed with an inert flyash
The solidification of wastes is analogous to the manufacture of concrete,
which is a mixture of coarse aggregate (gravel), fine aggregate (sand), and a
binder (cement). Water chemically reacts with the binder to form a solid
matrix of the components. In solidification, the waste supplies the water and
(depending on its composition) a greater or lesser fraction of the aggregate.
Clearly, the two mixtures can be formulated differently. When manufacturing
concrete, strength is essential. As a result, the binder, water, aggregate
and cement are mixed in proportions that optimize this property. The purpose
of S/S is to chemically react the water to form a solid, and to immobilize the
contaminants. The product only has to achieve a minimal load bearing
strength. The hazardous waste regulations only require an unconfined
compressibility strength of 50 psi.
It is, clearly, impossible to discuss all combinations of binders herein;
however, for the purpose of ORGANIC AIR emissions, this is not necessary.
Regardless of the binder formulations used, the concepts are the same and can
be illustrated by the following examples:
1. aqueous waste
2. aqueous waste
3. aqueous waste
solidified/stabilized
solidified/stabilized
solidified/stabilized
with portland cement/flyash
with lime kiln dust/flyash
with agricultural lime/flyash
Flyash from some coal-fired power plants are very reactive and will
set-up, much like cement, when mixed with water. Such flyashes are sold in
commerce and commonly used as a concrete additive. They can be considered to
behave in a similar manner to portland cement with regards to organic air
emissions. They type of flyash discussed here, is the less valuable variety.
When mixed with the lime or lime kiln dust, it participates in the chemical
reaction. When mixed with portland cement, however, it is relatively inert.
It serves as a source of aggregate and as a bulking agent to absorb the free
water.
2-7
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TABLE 2-1. COMMERCIAL WASTE STABILIZATION PROCESSES
Vendor
Process Name
Ingredients
Comments
Chemfix, In
IU Conversion
Dravo Lime
Envirotech
(Subsid. of
Chemfix)
Velsicol
Stabitrol Corp
TRW Systems
Chemfix
Sealosafe
Stablex
Calcilox
Envirotech
Velsicol
Terra-Tite
Cement + Soluble
Silicates
Silicates
Glassy Slag and
Scrubber Sludge
Cement and Silicates
Fly Ash, Scrubber
Sludge and Cement
Cement
1. Cement, Plaster
and Lime
2. Polybutadiene
Resin
U.S. Gypsum
Envirostone Gypsum
Probably does
not fix most
volatile organics
Probably does
not fix oils
solvents,
grease
volatile organics
Designed to fix
scrubber sludge.
probably does not
fix most volatile
organics
U.S. Patent
3,837,872
Claims to stabilize
organics; not
specific
Probably does not
fix most volatile
organics
Does not fix
volatile organics
May Work for
organics; very
costly
Does not fix
volatile organics
2-8
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2.2.2 Oraanics
The organic binders are rarely used commercially because of their high
cost compared to inorganics. They have been proposed for use on wastes
containing organic constituents. Organic binders can be broken into two broad
categories(1) bitumen and (2) polymers.
As much as S/S with portland cement is analogous to the manufacture of
concrete, the use of asphalt/bitumen is analogous to the manufacture of
asphalt concretecommon paving asphalt. In the latter case, the bitumen or
tar replaces the cement to bind the aggregate. Bitumen is not a suitable
binder for wastes containing water. In fact, the solid material has to be
dried prior to mixing with the hot tar. This process has only been used to a
limited extent for solidifying soils containing low level radioactive
materials and not for hazardous wastes. As a result, this binder will not be
discussed separately here.
Polymeric binders have been proposed for the S/S of hazardous wastes. In
this application, the wastes are mixed with a material such as expanded clay
or flyash to absorb free liquids. The mass is then mixed with a polymer or
polymer precursor and allowed to harden. Polymers that can be used include
epoxy, polyesters, polyolefins, and urea-formaldehyde. Polymeric binders do
not react chemically with most types of wastes. Rather, they encapsulate the
hazardous constituents and prevent them from being released to the
environment. Polymers typically cost on the order of 25 cents to several
dollars/lb. This could translate to a cost of $500 and up per ton of waste
stabilized just for the binder. Adding the cost of labor, capital, and
operating costs, could readily bring the cost of stabilization with polymeric
materials up to that for incineration. It is, therefore, unlikely that
polymers will be used as binders to a significant extent in the foreseeable
future. They will not be discussed further herein.
2.2.3 Organic/Inorganic Mixtures
Combinations of inorganic and organic binders have been proposed in the
past to S/S hazardous waste. These include diatomaceous earth with cement and
polystyrene; polyurethane and cement, and polymer gels with silicate and lime
cement. As with organic binders, these are relatively expensive for the same
reason as the polymeric binders. They will not, likely be used in large
volumes in the foreseeable future and will not be discussed further herein.
2.3 INDUSTRY TREND
S/S appears to be a growing industry. At present, it is used to
eliminate free water from wastes and to immobilize heavy metals to make them
suitable for land disposal. As land ban rules take effect, it will be
necessary to pretreat more types of waste to reduce their Teachability. EPA
has specified several types of pretreatment technologies such as incineration,
S/S, and chemical treatment as a "Best Demonstrated Control Technology"
(BOAT). Of those proposed, industry has had the most experience with
incineration and S/S. Incineration has shown itself to be useful for the
destruction of organic contaminants but with limited applicability for
inorganics, especially heavy metals. S/S has had good success in immobilizing
2-9
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heavy metal and other inorganic contaminants. As the BOAT regulations come
into effect for increasingly more categories of waste, the amount of waste
being treated in this way will continue to grow.
It is not likely that new types of binders will be used in the
foreseeable future. By and large, inorganic binders based on waste products
such as cement kiln dust, lime kiln dust or flyash will continue to be used.
In applications where waste materials are unavailable or unsuitable, high
volume, relatively low cost and readily available inorganic binders such as
Portland cement or lime will continue to be the binder of choice. These have
been shown to satisfactorily immobilize metals (based on current testing
procedures) and there appears to be little incentive to use other, more costly
binders.
Organic binders have been available for over a decade. They have
generally been proposed to stabilize wastes that have a high organic content,
the very wastes that are addressed by this document. It does not, appear,
however, that such binders will be used to a significant extent in the
foreseeable future.
As discussed above, asphaltic binders are not suitable for hazardous
waste application (they cannot tolerate water). There does not appear to be
any reason why they should be used in this application in the foreseeable
future.
Polymeric binders are not likely to be used for stabilizing hazardous
waste because of their very high cost. The raw materials of even the least
expensive polymer could cost more than $0.25/pound or $500/ton. Many binders
could cost even more. By the time the handling and other costs are added, S/S
with this type of binder could easily cost $1,000 or more per ton. At these
costs, it would be more economical to pretreat a waste prior to S/S.
For example, an aqueous waste containing organics and heavy metals could
be pretreated by a technique such as physical separation and air stripping to
remove the volatile organics and then solidified/stabilized with cement kiln
dust and flyash. If the organic content of the waste is higher, the waste
could be incinerated and then the ash, containing the heavy metals could be
stabilized with an inorganic, if necessary. Because of the existence of such
alternate waste treatment techniques, it is unlikely that the use of high-cost
binders, such as polymerics, will increase.
It is likely, however, that the types of equipment used for S/S will
change. At present, the bulk of the processing is conducted in open
equipment. Restrictions on organic emissions from these processes will
probably shift the economics for many applications in favor of closed mixing
equipment. The open systems would require large enclosures or hoods to
capture organic emissions. The air flow through these systems would be
relatively large with the inherently high costs associated in controlling
these. Closed systems could be controlled by using much lower gas flow rates
and, as a result, lower capital and operating costs for the portion of the S/S
system. While the economics of each individual application will govern the
processing equipment selected, it appears that regulations on organic air
emissions will result in an increase in the use of enclosed systems.
2-10
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REFERENCES
1. Weitzman, L., Hamel, L., and Cadmus, S. "Volatile Emissions from
Stabilized Waste." Final Report, Contract 69-02-3993, WA 32 and 37, Risk
Reduction Engineering Laboratory, U.S. Environmental Protection Agency,
Cincinnati, Ohio, 1988.
2. Weitzman, L. and Hamel, L. "Evaluation of Solidification/Stabilization as
a BOAT for Superfund Soils." Final Report, Contract 68-03-3241, WA 2-18,
Risk Reduction Engineering Laboratory, U.S. Environmental Protection
Agency, Cincinnati, Ohio, September 1988.
3. Weitzman, L. "Air Emissions From Hazardous Waste Landfills." Final
Report, Contract 68-02-3993, WA 22, Risk Reduction Engineering
Laboratory, U.S. Environmental Protection Agency, Cincinnati, Ohio,
September 1988.
4. Balfour, W.D., Wetherold, R.G., and Lewis, D.L. "Evaluation of Air
Emissions from Hazardous Waste Treatment, Storage and Disposal
Facilities." Final Report Contract, 68-02-3171, Hazardous Waste
Engineering Research Laboratory, U.S. Environmental Protection Agency,
Cincinnati, Ohio, June 1984.
5. Cullinane, J., and Jones, L., "Handbook for Stabilization/Solidification
of Hazardous Waste." Final Report Interagency Agreement, ********, Risk
Reduction Engineering Laboratory, U.S. Environmental Protection Agency.
Cincinnati, Ohio, 1988.
6. U.S. Environmental Protection Agency, Draft EIS. Hazardous Waste TSDF.
"Background Information for Proposed RCRA Air Emissions Standards",
Volume 1 - Chapters, Volume 2 - Appendices, March 1988.
7. U.S. Environmental Protection Agency, "Air Emissions from Municipal Solid
Waste Landfills - Background Information for Proposed Standards and
Guidelines", Preliminary Draft. March 1988.
2-11
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DISCUSS
Waste characteristics
Binders
Mixing techniques
(later talk)
STABILIZED
WASTE
SOLID WASTE
END LOADER
STORAGE P1LE(S)
Generalized Pozzolanic Process Flow Diagram
BASIC APPROACH TO STABILIZATION
OF INORGANIC CONSTITUENTS
* Mix the waste with materials which
convert the target constituents
into relatively insoluble compounds
Encapsulate the insoluble compounds
in a matrix which reduces access by
leachate and water
- macroencapsulate
- microencapsulate
2-12
-------
MICRO- VS MACRO-
ENCAPSULATION
Blurred line
Function of test method
KEY FACTORS
Waste properties
and composition
Binders
Mixing techniques
WASTE RECYCLE (IF
MORE TREATMENT
IS NEEDED)
Flow Diagram of S/S Operation of Chem Met Services
2-13
-------
IMPORTANT WASTE
PROPERTIES
Water content
- physical state
Hazardous constituents
- inorganic
- organic
WATER CONTENT
Binder must chemically react
with the water (solidification)
Commonly done by hydrate
formation
WHAT TAKES PLACE
DURING S/S
* Water Chemically Reacts
Hazardous constituents are made
less soluble
Hazardous Constituents are Encapsulated
- Reduce contact with the environment
FORTUNATELY!
2-14
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S/S BINDER TYPES
Cement based binders
- Portland cement
- Cement kiln dust
- Cement/flyash
- Natural and artificial pozzolans
* Lime/limestone/quicklime
- Lime kiln dust
- Lime/flyash
Absorbents
- Hydro- and organo- philic clays
- Wood chips, etc.
generally not acceptable
(1 of 2)
S/S BINDERS
Thermoplastic materials
- asphalt/bitumen
- thermoplastic polymers
Thermosetting polymers
Vitrification
(2 of 2)
POZZOLAN
Naturally occuring material
that reacts to form a solid
on addition of water or lime
with water
2-15
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VAST MAJORITY OF S/S WITH
CEMENT BASED BINDERS
WHY?
Consider Portland Cement
CEMENT BASED BINDERS
Most common type
Analogous to the manufacture of concrete
- aggregate (coarse and fine)
- water
- cement
Basic concepts apply
NORMAL APPROACH
TO S/S
1. Chemically react all water
2. Insolubilize hazardous constituents
3. Encapsulate products
2-16
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TYPES OF PORTLAND
(WT %)
Compound 1 II
Tricalcium 53 47
Silicate
Dicalcium 24 32
Silicate
Tricalcium 8 3
Aluminate
Tetracalcium 8 1 2
Aluminate
Total 93 94
Source: Portland Cement Association
CEMENTS
in
58
16
8
8
90
IV
25
54
2
12
94
2(3CaซSi02)
Tricalcium Silicicate
6H20
Water
3CaOป2Si02ป3H20
Tobermorite Gel
-t- 3Ca(OH)2
Calcium Hydroxide
2(2CaOปSi02)
Dicalcium Silicate
4H20
Water
3CaOซ2Si02ซ3H20
Tombermorite Gel
Ca(OH)2
Calcium Hydroxide
4CaOซAl203ปFe203
Tetracalcium Aluminate
10H20
Water
+ 2Ca(OH)2
Calcium Hydroxide
6CaOซAl203ซFe203ซ12H20
Calcium Aluminate Ferrite
3CaOซAl203
Tricalcium Aluminate
12H20
Water
+ Ca(OH)2
Calcium Hydroxide
3CaOซAl203ปCa(OH)2ป12H20
Tetracalcium Aluminate Hydrate
Source: Portland Cement Association
PORTLAND CEMENT
Dicalcium silicate"! ..
+ r^
Tricalcium silicatej
Tobermorite gel
3CaO-2SiO2.3H20
+
Lime
Ca(OH)2
2-17
-------
The cement ties up
free water four ways
SOLID PHASE-
SURFACE ABSORBED WATER
COORDINATED WATER
NONCOORDINATED O
WATER-,, 9
-s o-o -<:<)
CHEMICALLY BOUND WATER
O-H20 O-HYDROXYL O-Mg OR Al
ฉ-OH O-OXYGEN ^-SILICON
STRUCTURAL WATER
Mechanisms Retaining Water and Ionic Materials
On and In Solid Phases (1 of 2)
CAPILLARY WATER OR PORE WATER,
Mechanisms Retaining Water and Ionic Materials
On and In Solid Phases (2 of 2)
2-18
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Cement also forms less
soluble compounds
SOLUBILITY OF SOME COMPOUNDS
OF TCLP CATIONS
Solubility of anionic salt in water
Cation
Pb + +
Zn + +
Cd+ +
Cu+
S - soluble,
SS - slightly
1 - insoluble
Cl" NOg OH" C0| ฃ
S S SS 1
S S S 1
SSI 1
SS S - 1
iOj
SS
s
s
D
D - decomposes, R - reacts
soluble (<0.02g/100cc)
(<0.002g/100cc)
Oxide
I
SS
I
I
chemically
(1 of 3)
SOLUBILITY OF SOME COMPOUNDS
OF TCLP CATIONS
Cation
Solubility of anionic salt in water
CI" NO OH" CO| 504 Oxide
S
I
S
S I I
s
S -- I
s
I
I
I
I
I
S - soluble. D - decomposes, R - reacts chemically
SS - slightly soluble (<0.02g/100cc)
I - insoluble (<0.002g/100cc) (2 of 3)
2-19
-------
SOLUBILITY OF SOME COMPOUNDS
OF TCLP CATIONS
Solubility of anionic salt in water
Cation Cl" NOg OH" C0| SO^ Oxide
Ni++ S S -- 1 S 1
Hg+ | D -- 1 D 1
Hg+ + S S 1 S SS
Ca++ S S S 1 S R
S - soluble, D - decomposes, R - reacts chemically
SS - slightly soluble (<0.02g/100cc)
I - insoluble (<0.002g/100cc) (3 of 3)
CAVEATS
Mixtures of compounds not always
the sum of the components
Components interfere with chemical
reactions, set-up, and S/S
Theory is a useful start
Solution is a
Mixture of Ions
/" N
Cr
CO
NO
2-20
-------
SOLUBILITY PRODUCT
Arij x Catj= KJ:
Ca++x OH"= Constant
Cr +3x 01"= Constant
Cr+6x Cl "= Constant
Mixtures form complex equilibrium
CONVERT TO INSOLUBLE SALTS
Summary
Normal approach is to saturate
with insoluble anion
j.e. CO|,OhT
Then combine with other, less
soluble cations
i.e. Ca++.Si+ +
to form complex insoluble compounds
Cement, lime, limestone, quicklime,
and flyash - all sources of these
anions and cations
NATURAL POZZOLANS
Some forms of lava and coral
Rarely used for S/S
Does not appear to offer any
operational or cost advantages
in most situations
2-21
-------
FLYASH WITH AND WITHOUT LIME
(Artificial Pozzolans)
Some coal power plant flyashes will
react with water and form hydrates.
similar to cement
Many more flyashes will do so with
the addition of lime (or lime kiln
dust)
FLYASH
Contains
- Silica
- Alumina
- Calcium oxide
Most flyashes do not harden
by themselves
Many flyashes will harden
when mixed with Ca(OH)2
or cement
A few contain enough Ca(OH)2
to harden by themselves
Note: Flyashes can contain metals
LIME/FLY ASH MIXTURES
(Artificial Pozzolans)
Flyash supplies silicon
Lime supplies Ca(OH) 2
Results in properties
chemically similar to
cement
2-22
-------
LIME BASED BINDERS
Lime (slaked lime) Ca(OH)2
Quicklime CaO
Limestone CaCQs
CaO + H20-^>Ca(OH)2
quicklime lime
Ca(OH)2+ CO2^CaCO3
lime limestone
LIME KILN DUST
Contains large amounts of
quicklime (lime) - CaO
Large temperature rise as it
is mixed with water to form
"slaked lime"Ca(OH)2
2-23
-------
WHEN USED WITH MATERIALS
LIKE COAL FLYASH
Calcium compounds react with
the iron, silicon and other metals
in an analogous manner as in
Portland cement
Artificial pozzolans
AGRICULTURAL LIME
Used to modify pH
Modifies physical properties
Generally limited ability
to stabilize most metals
NOTE ON CYANIDES
Alkalinity of cement and lime
based binders is important in
their stabilization
If properly done, possible
to fix them
Chemistry is crucial
2-24
-------
ADDITIVES/MODIFIERS
Sodium silicate, NaSiO2
(water glass)
- additional silicon
- claimed to form NaSiAl gels
- fills pores in product
- does reduce leaching of
contaminants at times
TYPES OF SORBENTS
Flyash
Limestone screenings
Clays
Zeolites
(see book)
HYDRO- AND ORGANOPHILIC CLAYS
Commonly used to absorb liquids prior to S/S
Lab tests have indicated that some organophillic
clays, chemically bond to organic liquids
- concern with bond strength
EPA's policy is uncertain now
In most cases the mechanism is merely
physical absorption
May have promise in combination with other binders
i.e. absorb then bind with cement
2-25
-------
NATURAL SORBENTS AND THEIR CAPACITY FOR REMOVAL OF SPECIFIC CONTAMINANTS
FROM LIQUID PHASES OF NEUTRAL, BASIC. AND ACIDIC WASTES
Neutral Waste
Contaminant (calcium flouride)
Ca
Cu
Hg
Zn
Ni
F
Total
CN-
COD
Zeolite (5054)*
Kaolinite (857)
Zeolite (8.2)
Kaolinite (6.7)
Acidic F.A.t (2.D
Basic F.A. (155)
Illite (175)
Kaollnite (132)
Acidic F.A. (102)
Acidic F.A. (690)
11 lite (108)
Basic Waste
(metal finishina sludge)
Illite
Zeolite
Kaolinite
Zeol i te
Kaolinite
Acidic F.A.
Zeol i te
Illite
Basic F.A.
Zeolite
IlTHe
Acidic F.A.
Kaolinite
Illite
Illite
Acidic F.A.
Vermlculite
(1280)
(1240)
(733)
(85)
(24)
(13)
(1328)
(1122)
(176)
Vermicul i te
Basic F.A.
(13.5)
(5.1)
(3.8)
(2.6)
(2.2)
(1744)
(1080)
(244)
Acidic Waste
(petroleum sludae)
Zeolite
Illite
Kaolinite
Zeol i te
Acidic F.A.
Kaolinite
Zeolite
Illite
Basic F.A.
Zeolite
(4.5)
(1.7)
Illite
Acidic F.A.
Kaolinite
Illite
Vermiculite
Acidic F.A.
Vermiculite
Illite
Acidic F.A.
(1390)
(721)
(10.5)
(5.2)
(2.4)
(0)
(746)
(110)
(1.7)
(10.8)
(9.3)
(8.7)
(3.5)
(12.1)
(7.6)
(2.7)
(6654)
(4807)
(3818)
* Bracket represents sorbent capacity in micrograms of contaminant removed per
gram of sorbent used. After Sheih (1979) and Chan et al. (1979).
t F.A. - fly ซsh
TYPICAL PHYSICAL AND CHEMICAL PROPERTIES OF COMMONLY USED NATURAL SOR8ENTS
Bulk
density
Sorbent (ka/m3)
Cation-
exchange
capaci ty
(meo/100 g)
Anion-
exchange
(meg/100 g)
Slurry
oH
Major mineral species
present
Fly ash. acidic 1187
Amorphous silicates,
hematite, quartz, mullite,
free carbon.
Fly ash, basic
1187
Calclte, amorphous
silicates, quartz,
hematite, mullite, free
carbon.
Kiln dust
Limestone
screenings
Clay minerals
(soils)
Kaolinite
641-890
1519
5-15
Calcite, quartz, lime (CaO)
anhydrite.
Calcite, dolomite.
Various, e.g., illite.
Can be relatively pure
kaolonite.
Vermiculite
Bentonite
100-500
100-120
Can be relatively pure.
Smectite, quartz, illite,
gypsum, feldspar,
kaolinlte, calcite.
Zeolite
Zeolite (e.g., heulondite,
lauroonlte. stilbite,
chabazite, etc.
From: Sheih (1979), Haynes and Kramer (1982), Grim and Guven (1978).
2-26
-------
CONCERNS WITH BINDERS
May themselves contain
metals or organics of concern
- Cement, flyash, etc. can
contain mercury, cadmium, etc.
in trace quantities
- Asphalts can contain naphthalenes,
other polycyclic organics
Composition can vary by source
SAMPLE
PORTLAND
CEMENT
CEMENT KILN
DUST (MBI)
TYPEC
FLYASH
COMPARISON OF REAGENT LEACHING
WITH RCRA LIMITS
TEST
TYPE
TOTAL
EPT
TOTAL
EPT
TOTAL
EPT
CONCENTRATION (mg/l) IN WASTE OR LEACHATE
CADMIUM CHROMIUM LEAD NICKEL
RCRA EPT LIMITS
DEUSTINQ LIMITS
DRINKING WATER STANDARDS
1.11
< 0.01
3.95
< 0.01
2.87
< 0.01
1.00
0.083
0.01
33.70
0.29
29.00
0.07
75.40
0.14
6.00
0.315
0.05
57.50
0.26
191.00
0.49
221.00
0.35
6.00
0.315
0.05
24.90
0.02
11.00
< 0.01
62.50
0.02
ASPHALT /BITUMEN
To understand, consider the manufacture
of asphaltic concrete
2*27
-------
ASPHALT/BITUMEN
Analogous to asphaltic concrete
Potential problem with the binder
containing organic hazardous
constituents
Organics in the waste tend to
dissolve the asphalt/bitumen
The waste must be "dry"
- water reduces the cohesion
of the solids and asphaltic
binder
The blend is generally temperature
sensitive
FAN
CYCLONE-
DUST-
LADEN GASES
HOT AGGREGATE
BUCKET ELEVATOR
Flow Diagram of a Typical Hot-Mix Asphalt
Paving Batch Plant
POLYMERIC BINDERS
(Thermoplastic, Thermosetting)
* Used to a limited extent with
radioactive wastes
- blocks of vitrified or otherwise
fixed waste coated with a polymer
Used to treat monomer wastes
from polymer production
Has some potential in treating
compatible wastes from Superfund
sites - usually as a final treatment
Very highly waste selective
2-28
-------
THERMOPLASTICS
Melt at higher temperatures
Usually melted into the waste
much as asphaltic binders
Examples:
- polyethylene
- polypropylene
THERMOSETTING PLASTICS
Monomers react at all temperatures
The polymer does not melt well - often
decomposes at higher temperatures
Examples:
- bakelite
- epoxies
Produce water on polymerization
COMMERCIAL PROPRIETARY
PROCESSES
Typically use variations
of basic concepts
2-29
-------
COMMERCIAL WASTE STABILIZATION PROCESSES
Vendor
Process Name
Ingredients
Comments
Chemfix, In
IU Conversion
Dravo Lime
Envirotech
(Subsid. of
Chemfix)
Velsicol
Staborol Corp
TRW Systems
Chemfix
Sealosafe
Stab!ex
Calcilox
Cement + Soluble
Silicates
Silicates
Glassy Slag &
Scrubber Sludge
Probably does not fix
most volatile organics
Probably does not fix
oils, solvents, grease,
volatile organics
Designed to fix scrubber
sludge, probably does
not fix most volatile
organics
Envirotech Cement & Silicates U.S. Patent 3,837,872
Velsicol Fly Ash, Scrubber
Sludge & Cement
Terra-Tite Cement
1. Cement, Plaster
& Lime
Claims to stabilize
organics; not specific
Probably does not fix
most volatile organics
Does not fix volatile
organics may work for
organics; very costly
Source: Chemical Waste Management
2-30
-------
AIR EMISSIONS FROM
S/S PROCESSES
Particulate
- usually regulated locally
Organic vapors
- regulations in final stages of
of development by EPA/OAQPS
S/S OF ORGANIC CONSTITUENTS
Rarely react with inorganic binders
Often interfere with binder
setting and inorganic reactions
Frequently vaporize during S/S
ORGANIC CONSTITUENTS
May volatilize
Lack of presence in leachate
not necessarily indicative
of stabilization
Air pollution problem
2-31
-------
z
o
w
U}
5
UJ
>
t-
<
_f
^
S
3
O
#
120-
1 10-
100-
90 -
80-
70-
60-
50-
40-
30-
20-
10-
0
IL2A % EMISSION
(CUMULATIVE: ACETONE and TCE)
i\
^
/ r\
./- - - ' "^""
;/
/
'
:
;
:
1
i 1 1 1 1 i i ^^ i i i i i i
0 20 40 60 10 20 30
MINUTES DAYS
Source: Weitzman, et al.
100-
90-
80-
70-
w
E 50
ui
# 40
30-
20-
10-
0
1
100-
90 -
80-
70-
z
ฐ 60-
w
w
1 50-
Ul
# 40-
30-
20-
10-
0
AVERAGE VOC EMISSIONS
AFTER MIXING
AVERAGE 1-PENTANOL EMISSIONS
DURING MIXING (SOLIDIFICATION AGENTS)
LIME KILN DUST/FLYASH
30
MINUTES
Source: Weitzman, et al.
PENTANOL
Source: Weitzman, et al.
2-32
-------
CONCLUSION
Organic Contaminants
Often volatilize
Interfere with S/S process
Dissolve or weaken polymers
and bitumen - compatibility critical
Weaken structural integrity of
S/S products
Increases porosity of product
- reduces effectiveness of
encapsulation
HOW TO DEAL WITH
ORGANIC CONSTITUENTS
Pretreat to remove
- air strip
- thermal strip
- steam strip
- wet oxidation
Chemically destroy
- few organics form stable.
nonmobile compounds under
mild conditions
Exception: monomers > polymers
(1 of 2)
HOW TO DEAL WITH
ORGANIC CONSTITUENTS
Increase ability of binder to
encapsulate organics
- sodium silicate
- surfactants
Does not chemically bind or destroy
organic compound
Mix in enclosed system with
collection/control
(2 of 2)
2-33
-------
Volume
Waste Increase
F006-High Solids (35%)
PC-Based System 7
KD-Based System 35
F006 - low Solids (10%)
PC-Based System 10
KD-Based System 65
B3OKMICS
100 TPP Operation, All Posts are In $/Ton
Chemicals Processing Testing
14
17
32
32
Total Cbst
Airspace=$20/tonAirspace=$80/ton
44
55
61
76
109
136
127
175
o
in
5
TJ
d)
~a
Effect of Project Size
On Treatment Cost
7
6
5 -
4
3
10000 20000 30000
Size of Project (tons)
40000
SUMMARY
Many S/S techniques to choose from
Need to understand the chemical
and physical processes
Theory is only the first step
Must then verify and validate
theoretical estimates with laboratory
and pilot-scale screening tests
before selecting alternatives
2-34
-------
DESCRIPTION OF
VITRIFICATION TECHNOLOGY
SECTION 3
Abstract 3-2
Slides 3-8
3-1
-------
VITRIFICATION TECHNOLOGIES
Mr. Jim Hansen
Geosafe Corporation
Kirkland, Washington
The Superfund Amendments and Reauthorization Act (SARA) mandated that
the Environmental Protection Agency (EPA) give priority to treatment
technologies that are: (1) permanent, (2) capable of reducing the toxicity,
mobility, and/or volume of hazardous materials, and (3) capable of being
performed on-site and in situ. These criteria have proven to be
particularly challenging in the difficult area of remediating contaminated
soils, sludges, sediments, and process tailings. A group of vitrification
technologies hold the potential to satisfy these objectives for many
contaminated solids applications. The accompanying figures and following
discussion provide a general description of this developing technology area.
Vitrification technologies are those that involve exposure of hazardous
materials to molten glass and related process conditions to affect the
destruction, removal, and/or permanent immobilization of hazardous
contaminants. Vitrification is defined as conversion of such solids into a
glass residual form through the application of heat to the point of fusion.
The technologies are applicable to use on solids that are capable of forming
a molten, vitreous mass, and of producing a glass-like residual product upon
cooling. Typically, the residual product is a solid (super-cooled liquid)
containing an amorphous mixture of oxides (primarily silica and alumina)
with little or no crystallization present.
Exposure of contaminants to vitrification processing results in several
desirable results: (1) destruction of hazardous organics by pyrolytic
decomposition and/or oxidation, (2) removal (partial or full) of
low-solubility, high-volatility, high-solubility inorganics in the residual
glass product through chemical incorporation and/or encapsulation. Thus,
the vitrification processes may be considered as both thermal treatment
(destruction) and immobilization processes.
The various vitrification processes similarly produce a glassy residual
product resembling natural obsidian in physical and chemical
characteristics. The residual product may be made in granular form, cast
into containers, or in multi-thousand ton monoliths. Typically the product
has excellent structural, weathering, and biotoxicity characteristics,
making it suitable for long-term environmental exposure. The residual
typically is able to surpass EPA leach testing requirements (e.g., EP-Tox
and TCLP), making it a candidate for deli sting as a hazardous waste.
There are several different processes that produce a vitrified product.
Most of these are performed ex situ, however one is performed in situ.
These basic processes are discussed below.
3-2
-------
Ex-SItu Vitrification
Ex-situ vitrification technologies include: (1) electric
furnace/melter, (2) plasma centrifugal reactor, and (3) slagging
kiln/incinerator.
The electric furnace/melter class includes processes that utilize a
ceramic-lined, steel-shelled melter, to contain the molten glass and waste
materials to be melted. Some of these processes utilize equipment quite
similar to electric glass furnaces that have widespread use for the
manufacture of glass products (e.g., bottles, plate products). Such melters
involve placement of waste materials and glass batch chemicals directly on
the surface of a molten glass bath. The majority of melting occurs at the
waste/molten glass interface as heat is transferred from the molten glass.
As such waste is heated, organics and inorganic volatiles are evolved and
either pyrolyzed or oxidized prior to off-gas treatment to ensure safe air
emissions.
Another class of melters involve feeding mechanisms that introduce the
waste materials below the molten glass surface. Such method of introduction
results in the pyrolysis of organic contaminants within the molten glass,
followed by evolution of pyrolyzed off-gases to the space above the glass
surface and thence to the off-gas treatment system. Both classes of melters
result in the incorporation of nonvaporizable inorganics into the molten
glass.
Periodically, the electric melters must be tapped to remove the
accumulated glass product. The molten glass may be cast directly into
containers. Another alternate utilizes a water bath to produce a granular
residual product. The containerized or loose residual product must then be
disposed.
The plasma centrifugal reactor varies significantly from the
melter/furnace concept. In the plasma reactor, prepared waste materials are
fed into a rotating reactor well in which a transferred-arc plasma torch is
operating. The plasma torch, which is capable of temperatures exceeding
10,000ฐC, heats the waste material beyond the point of melting to about
(typically) 1,600ฐC. The melted material is allowed to fall into a slag
chamber where it is collected in a container.
Organics and other volatiles emitted during the plasma heating are
passed to a secondary combustion chamber into which an oxidizing gas is
added. The resulting off-gases are then transferred to an off-gas treatment
system to ensure safe air emissions. The containerized slag must eventually
be disposed.
Last, solids may be vitrified in rotary kilns and incineration equipment
that is operated in a slagging mode. Large kilns are able to accommodate
whole drums and mixed solids with little or no pretreatment being required.
3-3
-------
Such large facilities are typically stationary as opposed to mobile, on-site
facilities. In these facilities, the vitrified product is removed from the
exit end of the kiln; it may be cast into containers or granulated as done
for the other technologies mentioned above.
Being ex-situ processes, it is necessary that application of each of the
above three classes of processes involve excavation, and possible
pretreatment of waste materials as required to allowing feeding and proper
treatment. In each case the residual product must be disposed; however, the
difficulties of such disposal may be minimized if the residual product is of
sufficient quality to be delisted.
In-Situ Vitrification
There is one vitrification technology, designated ISV for in-situ
vitrification, which brings the benefits of the molten glass exposure and
high quality glass residual product to the in-situ application area. The
ISV process system has been developed and demonstrated through large-scale;
wastes treated include a variety of hazardous chemical, radioactive, and
mixed (hazardous chemical and radioactive) wastes.
The ISV process electrically melts inorganic materials (e.g., soil) for
the purpose of thermochemical treating free and/or containerized
contaminants present within the treatment volume. Most ISV applications
involve melting of natural soils; however, other naturally occurring or
process residual inorganics (e.g., sludge, tailings, sediments), or process
chemicals may be utilized. When used to treat contaminated soil, the
process simultaneously destroys and/or removes organic contaminants while
chemically incorporating (immobilizing) inorganic contaminants into a
chemically inert, stable glass and crystalline residual product.
An array (usually square) of four electrodes is placed to the desired
treatment depth in the volume to be treated. As electric potential is
applied between the electrodes, current flows through the starter path,
heating it and the adjacent soil to temperatures above 1600ฐC, which is well
above typical soil fusion temperatures. Upon melting, typical soils become
quite electrically conductive; thus the molten mass becomes the primary
conductor and heat transfer medium allowing the process to continue beyond
startup. Continued application of electric energy causes the molten volume
to grow downward and outward encompassing the desired treatment volume. The
rate of melt advance is in the 1 to 2 in/hr range. Individual settings
(i.e., the melt involved with a single placement of electrodes) may grow to
encompass a total melt mass of up to 1000 ton and a maximum width of about
30 ft. Single setting depths as great as 30 ft are considered possible with
the existing large-scale ISV equipment. Adjacent settings are positioned to
fuse to each other and to completely process the desired volume at a site.
3-4
-------
The molten soil mass 1s typically 1n the 1600 to 2000ฐC temperature
range; specific temperatures are dependent on the overall chemistry of the
melt. Within the melt, a vigorous, chemically reducing environment 1s
typical. Because soil typically has low thermal conductivity, a very steep
thermal gradient (I.e., !50-250ฐC/1n) precedes the advancing melt surfaces.
Typically, the 100ฐC Isotherm 1s less than 1 ft away from the molten mass
Itself. The soil volume between the 100ฐC Isotherm and the melt 1s termed
the dry zone; this zone has maximum vapor permeability as 1t exists without
water present 1n the liquid state.
The large-scale ISV system melts soil at a rate of 4 to 6 ton/hr. Since
the void volume present 1n particulate materials (e.g., 20-40% for typical
soils) 1s removed during processing, a corresponding volume reduction
occurs. Also, since some of the materials present 1n the soil are removed
as gases and vapors during processing (e.g., humus, organic contaminants),
further volume reduction occurs. The volume reduction creates a subsidence
volume above the melt and an angle of repose 1n the soil adjacent to the
melt. Upon cooling, an obsidian-like vitrified monolith results (silicate
glass and microcrystalline structure); this product possesses excellent
structural and environmental properties.
The process utilizes a mobile, on-site equipment system. Electric power
1s usually taken from a utility distribution system at transmission voltages
of 12,500 or 13,800 volts; alternatively the power may be generated on site
by a diesel generator. The 3-phase power is supplied to a special
multiple-tap transformer (Scott Tee) that converts the power to 2-phase and
transforms 1t to the voltage levels needed throughout the processing. The
electrical supply system utilizes an isolated ground circuit which provides
appropriate operational safety.
Flow of air through the hood is controlled to maintain a negative
pressure (0.5 to 1.0 1n H20). An ample supply of air provides excess
oxygen for combustion of pyrolysis products and organic vapors, if any
evolve from the treatment volume. The off-gases, combustion products and
air are drawn from the hood (by induced draft blower) into the off-gas
treatment system which utilizes the following unit processes to ensure
compliant air emissions: (1) quenching, (2) pH controlled scrubbing,
(3) dewatering (mist elimination), (4) heating (for dewpoint control),
(5) particulate filtration, and (6) activated carbon adsorption. A
self-contained glycol cooling system is utilized to cool the quenching/
scrubbing solution; this avoids the need for a constant on-site water
supply. The amount of moisture present in the exhaust air stream is
controlled to accommodate the moisture that is removed form the treatment
volume during processing.
A backup off-gas treatment system is provided to accommodate the
possibility of power failure. The backup system employs a diesel-powered
generator, blower, mist cooler, filter and activated carbon column. The
backup system is capable of removing and treating off-gases during a power
outage or during the Initial cooling time at completion of a setting.
3-5
-------
The disposition of contaminants during ISV processing is dependent upon
many variables, the most important of which may be grouped into the
categories of: (1) pre-melt soil properties, (2) contaminant quantities and
properties, and (3) molten zone properties and conditions. Disposition of
contaminants depends on the response of the contaminants to the process
conditions; individual contaminants may respond to the system of processing
variables in several ways, including: (1) change of state, (2) physical
movement, and (3) physical/chemical reaction.
There are five (5) basic types of mechanisms that relate to movement
responses of contaminants during processing; including: (1) capillary
action, (2) concentration-based diffusion, (3) thermally induced vapor
transport, (4) melt convective flow, and (5) liquid/vapor adsorption on
soil. The combination of processing conditions and responses of
contaminants may result in five (5) basic dispositions of the contaminants,
including: (1) destruction of compounds, (2) physical removal from the
treatment volume to the off-gas treatment system, (3) chemical incorporation
into the vitrified product, (4) physical encapsulation within the vitrified
product, and (5) continued existence as a minor residual within the
treatment zone.
Certain response types and ultimate dispositions are dominant for
various classes of contaminants. As organic vapors distribute themselves
throughout the void space adjacent to the melt, they increase in temperature
to their pyrolysis temperature, where they break down into successively
smaller chains of molecules and eventually reach the state of elemental or
diatomic gases. Upon pyrolysis, the concentration of the original compound
vapor is thereby diminished, resulting in a continued concentration gradient
of the original vapor toward the pyrolysis isotherm (i.e., toward the
melt). For hazardous organic contaminants, pyrolytic destruction is the
dominant disposition; destruction efficiencies in the soil column (prior to
off-gas treatment) on the order of 99.9 to 99.995 wt% have resulted from ISV
tests involving hazardous organics. The level of destruction can be
increased by recycling the organics recovered in the off-gas system to a
subsequent ISV setting. Chemical incorporation is the dominant disposition
of hazardous inorganic elements (e.g., heavy metals). The ISV silicate
glass is very durable relative to environmental exposure and will hold a
wide variety of materials in nonleachable form. In addition to chemical
incorporation, some amount of volatile or semi-volatile inorganics (e.g.,
Pb, Hg) may be removed from the treatment volume and recovered in the
off-gas treatment system; they may then be disposed by an alternative means
or be recycled to a subsequent ISV melt for further disposition by chemical
incorporation.
The contaminated soil subject to ISV treatment may be configured in
numerous ways for processing. The material may be processed in situ where
is presently is, or it may be staged above or below grade for treatment.
Special cases also include containerized treatment, stacked settings for
deep contamination, continuous feeding arrangements for high volume
reduction material, and special conditions for vitrifying underground tanks.
3-6
-------
The ISV process can also accommodate significant quantities of
inclusions in the treatment volume. Inclusions are defined as highly
concentrated contaminant layers, void volumes, containers, metal scrap,
general refuse, demolition debris, rock, or other non-homogenous materials
or conditions within the waste volume.
REFERENCES
Eschenbach, R.C., et al. "Process Description and Initial Test Results with
the Plasma Centrifugal Reactor". Presented at the Forum on Innovative
Hazardous Haste Treatment Technologies: Domestic and International,
June 19-22, 1989. Retech, Inc., Ukiah, California.
Penberthy Electromelt International, Inc. 1984. "Penberthy PYRO-CONVERTER
for Hazardous Wastes Liquid and Sludge, Organic and Inorganic". PC-1.
Penberthy Electromelt Int'l., Inc. Seattle, Washington.
Schiegel, Ronald. "Residues from High Temperature Rotary Kilns and Their
Leachability". Presented at the Forum on Innovative Hazardous Waste
Treatment Technologies: Domestic and International, June 19-22, 1989.
W+E Environmental Systems, Germany.
Koegler, S.S., et al. 1988. Vitrification Technologies for Weldon Spring
Raffinate Sludges and Contaminated Soils Phase I Report: Development of
Alternatives. PNL-6704; UC-510. Pacific Northwest Laboratory, Richland,
Washington.
Buelt, J.L., et al. 1987. In Situ Vitrification of Transuranic Waste; An
Updated Systems Evaluation and Applications Assessment. PNL-4800,
Supplement 1, Pacific Northwest Laboratory, Richland, Washington.
Geosafe Corporation, 1989. Application and Evaluation Considerations for In
Situ Vitrification Technology; a Treatment Process for Destruction and/or
Permanent Immobilization of Hazardous Materials. GSC 1901, Geosafe
Corporation, Klrkland, Washington.
Geosafe Corporation, 1989. "In Situ Vitrification for Permanent Treatment
of Hazardous Wastes". Presented at Advances In Separations: A focus on
Electrotechnologies for Products and Wastes, April 11-12, 1989. GSC 1903,
Geosafe Corporation, Kirkland, Washington.
Reimus, M.A.H. 1988. Feasibility Testing of In Situ Vitrification on New
Bedford Harbor Sediments. Battelle, Pacific Northwest Laboratories,
Richland, Washington.
Tlmmerman, C.L. 1986. In Situ Vitrification of PCB-Contaminated Soils.
EPRI CS-4839. Electric Power Research Insitute, Palo Alto, California.
Mitchell, S.J. 1987. In Situ Vitrification of Dioxin-Contaminated Soils.
Battelle, Pacific Northwest Laboratories.
3-7
-------
VITRIFICATION TECHNOLOGIES
DEFINITIONS
GLASS - A solid (super-cooled liquid)
containing an amorphous
mixture of oxides (primarily
silica) with little or no
crystallization present
VITRIFY - To convert solids into glass
through heat fusion
TREATMENT MECHANISMS
1) Destruction of Organics
Pyrolytic decomposition
Oxidation
2) Removal of Inorganics (partial to complete
for low-solubility, high-volatility materials)
3) Immobilization of Inorganics in Residual
Glass Product
Chemical incorporation
Encapsulation
3-i
-------
TYPICAL RESIDUAL PROPERTIES
Composition:
Strength:
Volume Reduction:
Toxicity Reduction:
Mobility Reduction:
Wet/Dry Cycling:
Freeze/Thaw Cycling:
Life Expectancy:
Analogous to natural obsidian
10X concrete
20-40 %
Organics are removed/destroyed
Inorganic-bearing residual found to
have acceptable biotoxicity (EPA)
Surpasses EP-Tox, TCLP
Unaffected
Unaffected
DOE glass waste form research
indicates geologic time period
VITRIFICATION TECHNOLOGIES
ALTERNATIVE VITRIFICATION
TECHNOLOGIES
Electric Furnace/Melter
Plasma Reactor
Slagging Kiln/Incinerator
In Situ Vitrification (ISV)
ELECTRIC MELTER/FURNACE
Waste Pre-
Treatmant
Glass Batch
Preparation
Melting
Glass Batch
and Waste
Off-Gas
Treatment
Joule-Heated
Ceramic-Lined
Melter
Molten Glass
3-9
-------
PLASMA CENTRIFUGAL REACTOR
Plasma Torch
Oxidizing Gas Input
Secondary Combustion
Chamber
Slag Chamber
SLAGGING KILN/INCINERATOR
VITRIFICATION TECHNOLOGIES
IN SITU VITRIFICATION
Graphite and
Glass Frit
Starter Path
Electrodes
to Desired
Depth
Subsidence
Backfill Over
Completed
Monolith
Contaminated
Soil Region
(D
(2)
3-10
-------
VITRIFICATION TECHNOLOGIES
BASIC COMPARISON OF TYPES (Page 1 of 2)
ELECTRIC
FURNACE/
MELTER
PLASMA
REACTOR
SLAGGING
KILN/
INCINERATOR
IN SITU
VITRIFICATION
APPLICABLE
MATERIALS
Dry/Wet
Solids
Dry/Wet
Solids
Dry/Wet
Solids,
Containers
(some only)
Dry/Wet
Solids,
Containers,
Rubble
WHERE
PERFORMED
Mobile,
On-Slte,
Ex-SItu
Mobile,
On-Slte,
Ex-SItu
Transportable,
On-Slte,
Ex-SItu
Mobile,
On-Slte,
In Situ
TYPICAL
OPERATING
TEMPERATURE
11-1.200C
1, 600 C (glass)
10,000 C
(plasma)
11-1,500 C
1 6-2,000 C
ORGANIC
DESTRUCTION
MECHANISM
Pyrolysls or
Oxidation
Oxidation
Oxidation
Pyrolysls
VITRIFICATION TECHNOLOGIES
BASIC COMPARISON OF TYPES (Page 2 of 2)
ELECTRIC
FURNACE/
MELTER
PLASMA
REACTOR
SLAGGING
KILN/
INCINERATOR
IN SITU
VITRIFICATION
TYPICAL
THROUGHPUT
RATE
0.5-3 tph
0.1-0.3 tph
6 tph
30 drums/h
4-6 tph
PRE-TREAT
REQUIRE-
MENTS
Excavate,
Sort, Particle
Size Screening
Excavate,
Sort, Particle
Size Screening
Excavate
(some sort and
particle size)
None
NATURE OF
RESIDUAL
Solid-filled
Containers
or Granular
Slag In
Container
Slag In
Container
Contiquous
Monolith
POST-TREAT
REQUIRE-
MENTS
Disposal
Residual
Disposal
of
Residual
Disposal
Residual
Backfill
Subsidence
IN SITU VITRIFICATION
TECHNOLOGY DEFINITION
In situ electric melting of staged or as-deposited
contaminated solids (e.g., soil, sediment, sludge,
tailings, various Inclusions) for purposes of:
1) organic destruction/removal
2) Inorganic Immobilization/removal
3) barrier wall formation
3-11
-------
IN SITU VITRIFICATION
PROCESS CONDITIONS
Off-Gas Collection Hood
(-0.5 to 1.0 In hPO)
Unaffected Soil
(minimum permeability)
Conductive Heating
(melt advance rate
of 1 to 2 In/hr)
Electrode (typ)
- 3,760 kva power level
- 0.3 to 0.4 kwh/lb treated
Soil Surface
100t Isotherm
Melt Surface
Dry Zone
- thermal gradient of
150to250ฐC/ln
- maximum permeability
Molten Soil Region
Joule heating between electrodes
1,600 to 2,000ฐC
- melt rate 4-6 tons/hr
molten oxides and contaminants
- chemically reducing environment
- convection currents
IN SITU VITRIFICATION
Relationship Between Adjacent Settings
6-7 ft
Clean Backfill
Original
Grade
IN SITU VITRIFICATION
EQUIPMENT SCHEMATIC
Off-Gas Hood
Controlled
Air Input
3-12
-------
IN SITU VITRIFICATION
CONTAMINANT MOVEMENT MECHANISMS
DURING ISV PROCESSING
Capillary Action - movement of liquids toward
dry zone
Molecular Diffusion - concentration-based
movement of vapors toward melt
Carrier-Gas Transport - stripping of vapors by
water vapor
Density Differential - movement of vapors Into
melt and toward surface
Pressure Differential - vapor flow toward
negative surface pressure
Convection - thermally Induced circulation
within melt
IN SITU VITRIFICATION
' MOVEMENT OF CONTAMINANTS
Angle of
Evolution of Pyrolysls Products,
Water and Other Vapors
Electrode
Subsidence
Capillary
Movement
Of Liquids
Concentration-
Based Diffusion
Toward Melt
100 C Isotherm
IN SITU VITRIFICATION
POSSIBLE CONTAMINANT DISPOSITIONS
Destruction (chemical/thermal)
Removal to off-gas treatment
Chemical Incorporation In glass residual
Physical encapsulation in glass residual
Continued existence as adjacent residual
3-13
-------
IN SITU VITRIFICATION
PRIMARY FACTORS AFFECTING
CONTAMINANT DISPOSITION
Contaminant physical/chemical properties
Melt chemistry
Melt temperature
Dwell time (viscosity, depth)
Adjacent soil properties
Soil moisture content
Degree of overmeltlng
TYPICAL ORGANIC RESULTS
99.9 to 99.995 wt%
pyrolyzed
0.1 to 0.005 wt%
evolved as vapor
Molten
Soil
S9.9000 to 99.98500 wt% Destruction
> 0.0999 to > 0.00499 Removal
> 99.9999 to > 99.99999 Total ORE
Organic
Typical Inorganic Results
Recycle
Option
199 to 99.99 wt%
I Immobilized In
Glass
0.01 to 1 wt%
evolved as vapor
Molten
Soil
Inorganic
3-14
-------
IN SITU VTTRIRCATION
TYPICAL CONTAMINANT DISPOSITION
Weight Percent
Destruction
Removal
(Recycle
Option)
Chemical
Incorporation
Mercury It nott
99.995
0.005
LV
99.9
0.1
MV
95
6
_HV
Organic
trie exception; nearly ซll 1* rem
0.01
89.99
HS4.V
1
99
HV-HS
LV-tS
5*
95*
HV-LS
Inorganic
oved
Note:
L = Low
M = Medium
H = High
V = Volatiles
S = Solubility
IN SITU VITRIFICATION
Residual Product Properties
Composition:
Structural Strength:
Wet/Dry Cycling:
Freeze/Thaw Cycling:
Chemical Leaching:
Blotoxlclty:
Life Expectancy:
Analogous to Natural Obsidian
10X Concrete
Unaffected
Unaffected
Zero Organics Present
Passes EP-Tox, TCLP
Acceptable (Near Surface Life)
Geologic Time Period
IN SOU VITRIFICATION
APPLICATION OPTIONS
In Situ - where now existing
Staged - where placed for treatment
Barrier Wall - partial treatment plus containment
In-Container - high-volume reduction materials
Stacked Settings - very deep treatment
3-15
-------
IN SITU VITRIFICATION
IN SITU PROCESSING ARRANGEMENT
Electrode (typ)
Clean Soil Cover
(optional)
\
Original Grade
Clean Soil
Typical Placement of
ISV Setting
Contaminated Soil Region
(surface source or landfill)
IN SITU VITRIFICATION
BELOW GRADE STAGING ARRANGEMENT
Clean Soil Cover
(optional)
Original
Grade
Subsidence /
Level '
Clean Soil
Typical Placement of
ISV Setting
Staged Contaminated Material
Prepared Trench
IN SITU VITRIFICATION
BARRIER WALL CONCEPT
Fusion
Impermeable Soil Layer
ISV Barrier Wall
(around Impoundment)
3-16
-------
IN SITU VITRIFICATION
1N-CONTAINER PROCESSING CONCEPT
Special Process
Container
Electrode
(typj
Container May Be Placed
Above, Below, or Partially
Below Grade
(4)
(Good BV Pmtnlni
Cotnpfetc (prttMttmiy
taofinlnujd)
STACKED SETTING CONCEPT
Dry Well or Other
Contamination
Source
Surface Grade
Upper
Vitrified Mass
Replacement of
Excavated Excavated Material
Volume
Clean Backfill
(4)
IN SITU VITRIFICATION
BASIC APPLICATION CONSIDERATIONS
Contaminants (type, concentration, depth,
required cleanup levels)
Solids (type, properties, moisture content,
stratigraphy)
Ground water (location, recharge rate)
Electricity (availability, price)
Inclusions (physical/chemical definition)
Structures (above/below surface)
Volume (depth, area arrangement)
3-17
-------
VITRIFICATION TECHNOLOGIES
APPLICABLE WASTE TYPES
Organic
Radioactive
Inorganic
Vitrification is Applicable to Mixtures of All Types
IN SITU VITRIFICATION
WATER CONSIDERATIONS
Process removes water
Fully saturated soils, slurries may be processed
Energy for water removal Increases cost
In-aquifer processing dependent on recharge
rate
In-aquifer options:
1) Lower water table
2} Reduce recharge rate
IN SITU VITRIFICATION
PUMPING TO LOWER WATER TABLE
Pump and
Treat Well
Conal
Depression
Groundwater Level
During Pumping
3-18
-------
IN SITU VITRIFICATION
GENERAL APPLICABILITY LIMITS
Combustible Liquids
(5-10wt%)
Void /
Volumes /
(Individual
<160 cu-ft)
Rubble
(10-20 wt%)
Y~l
Combustible
Solids
^V~- (5-10wt%)
Combustible
Packages
Ondlvldual
<30 cu-ft)
Continuous Metal
(
-------
IN SITU VITRIFICATION
Major Variables Affecting Cost
Variable
Unit Price of Electricity
Soil/Waste Moisture Content
Depth of Processing
Size (Volume of Site)
Soil Type
Staging Requirements
Typical Case
$0.03 - .06/kwh
10-20 wt%
10-20 ft
3 - 50,000 cy
Sand - Clay
Minimal
Typical ISV Cost: $250 - 350/ton
o-,,,. -,_ c r>~^. (excludes treatablllty testing, technical support,
Source: Geosafe Corp.vinol),|lzaacilA,einobj,Iiath)n^
IN SITU VITRIFICATION
POWER REQUIREMENTS
12.5 or 13.8 kva supply
Total of 4 Mw available
Consumes 0.3 to 0.4 kwh/lb treated
May be dlesel-generated If not readily
available from local utility
IN SITU VITRIFICATION
TECHNOLOGY BACKGROUND/STATUS
Originally DOE technology (transuranlc oriented)
Developed/demonstrated through large-scale
($15m since 1980)
Comrrtetclal capability established 1989
SITE Program evaluation at site selection stage
Numerous Superfund treatability tests completed
Numerous RI/FS and RCRA CA studies evaluating
Superfund procurements In process
3-20
-------
PHYSICAL TESTING METHODS
FOR DETERMINING EFFECTIVENESS
OF S/S PROCESSES
SECTION 4
Abstract 4-2
Slides 4-5
4-1
-------
PHYSICAL TESTING METHODS FOR DETERMINING THE
EFFECTIVENESS OF S/S PROCESSES
Mr. Peter Hannak Mr. Richard McCandless
CH2M Hill UC/Center Hill Lab
Waterloo, Ontario Cincinnati, Ohio
Physical and Engineering testing methods are applicable to:
untreated S/S wastes
site characterization (excavation and disposal)
treatability studies
S/S process control
S/S product evaluation
Results of tests may be used directly for the assessment of the waste.
However, properties such as porosity and volume increases are calculated
from the results of appropriate tests.
The physical properties of S/S wastes provide the means to:
establish treatment objectives and to measure the effectiveness of
contaminant immobilization
compare a variety of treatment processes and enable the selection
of suitable processes
evaluate economics of the S/S process and minimize associated cost
assure safety of operations and product
minimize any air or liquid emissions during the processing phase
The physical/engineering test results are to be used to supplement the
results of chemical testing, therefore interpretation of S/S process
evaluation should include both groups of tests.
The physical/engineering test may be grouped into two categories as to
the type of information which can be obtained.
characterization of intrinsic waste properties
site-specific information
The full understanding of the behavior of the waste at a site, can only be
described if both types of information are available. The testing methods
that are applicable to the untreated wastes includes methods related to:
liquid solid classification
particle size analysis
moisture content
bulk density
permeability and
strength
4-2
-------
The Inter-relationship of these tests and purpose of their application
to S/S process evaluation are discussed in the presentation.
Further discussion of specific nethods include tests of regulatory
Importance (Paint Filter/Liquid Release tests), tests used as guidance
(Unconfined Compressive Strength Tests) and tests required for site/waste
characterization, including field permeability.
Approach and equipment are described to provide application guidance for
the audience. The signification and limitations of the individual nethods
are presented along with the applicable literature and standard references.
The scientific background of complex tests, such as permeability
measurement, Is presented in the foriat of charts and equations where
necessary.
The function of physical/engineering tests for process characterization
are also discussed. These functions include the use of tests for process
control and treatability studies on bench and pilot scale.
Mechanisms of interferences affecting the final physical/engineering
properties of the S/S wastes are detailed as follows:
adsorption
complexion
precipitation
nucleation
The inter-relationships of physical/engineering tests performed on the
final product are also presented. The applicable tests include:
bulk density
specific gravity
moisture content
permeabi11ty
weathering resistance
unconfined compression
These tests are presented in detail including the modifications of
procedures to make these tests suitable to S/S wastes.
The application of specific tests under development will expand the
understanding of the process and assist in the evaluation of the quality of
the S/S waste products. Specific examples include; nicrocharactenzation
and dissolution tests.
A discussion concerning the range and inter-relationship/trend of
properties is provided. The support for the discussion is based on a series
of unpublished experiment results from an international cooperative study
4-3
-------
carried out with the participation of the industry. This study
characterized waste streams from a variety of sources including:
Synthetic wastes
Wood preservative wastes
Dredge spoil
Electroplating wastes
The characterization of waste stabilized by commercial processes provides a
cross-section of S/S waste properties outlined in this presentation.
REFERENCES
Hannak, P., Liem, A., "Development of a Method for Measuring the
Freeze/-Thaw Resistance of Solidified/Stabilized Wastes", Proceedings of the
International Conference on New Frontiers for Hazardous Waste Management,
Sept. 15-18, Pittshurgh, PA EPA/600/0-85/025.
Hannak, P., Liem, A., development of New Methods for Solid Waste
Characterization, Part 2: Measurement of Porosity of Solidified/Stabilized
Wastes", Presented to the International Seminar on Solidification and
Stabilization of Hazardous Waste '86, Hazardous Waste Research Centre,
Louisiana State University, Baton Rouge, LA.
Jones, J.N., Bricka, M.R., Myers, T.E. and Thompson, D.W. Factors Affecting
Stabilization/Solidification of Hazardous Wastes. Proceedings of the
International Conference on New Frontiers for Hazardous Waste Management.
EPA 600/9-85-025.
Kingsbury, G., Hoffman, P., Lesnik, B. The Liquid Release Test (LRT).
Proceedings of the Fifth Annual Waste Testing and Quality Assurance
Symposium, July 24-28, 1989. American Chemical Society.
P.E.I. Associates and the Earth Technology Corporation.
Stabilization/Solidification of CERCLA and RCRA Wastes. Physical Tests,
Chemical Testing Procedures, Technology Screening and Field Activities.
EPA, 1989. Draft.
Physical and Engineering Properties of Hazardous Wastes and Sludges. EPA
600/2-77-139, NTIS PB, 272 266/AS.
U.S. Army Engineer Waterways Experiment Station. Physical Properties and
Leach Testing of Solidified/Stabilized Industrial Wastes. NTIS PB 83-147983
Shively, W. and Dethloff, S. Hazardous Waste Treatment Demonstration Guide,
Test Methods for Solidification/Stabilization of Hazardous Wastes. CH2M
Hill, Second Draft, 1987.
4-4
-------
SCOPE
Untreated waste/site
Treatabity studies
(Process)
S/S wastes
Does not include sofl testing
SIGNIFICANCE OF WASTE
CHARACTERIZATION
Establish treatment objectives
Select the best treatment option
Minimize treatment cost
Assure safety of operations
* Minimize by-products and emissions
INFORMATION REQUIREMENTS FOR
SOLID WASTE LANDFILL DESIGN
4-5
-------
TESTING METHODS OF UNTREATED WASTES
Liquid/solid classification
Particle size and distribution
Moisture content
Buflc density
Permeability
* Strength
INTERRELATION OF SITE/UNTREATED
WASTE TESTING
Test
Property
Significance
Moisture/
solids
content
1
^*
L/S class-
ification
Liquid
Release
Permeability
convectlve
transport
UCS and
cone Index
Physical
Integrity
Particle
size
dlstrbutlon
Contact
area
^
Bulk
density
weight/
volume
reduction
}
H
H
H
H
i
4-6
-------
LIQUID/SOLID CLASSIFICATION
Regulation: Land ban, HSWA prohibits disposal
of bulk liquid hazardous waste and hazardous
waste containing free liquid
Tests:
- Paint Filter Test (SW 846-9095)
- Liquid Release Test
PRESSURE
APPICATIONH
DEVICE
MEANS OF UQUID RELEASE
Gravitation
Capfflary forces
Pressure
Microstructural dehydration
Wash out
Degradation
- physical
- biological
FILTER
PAPER
STAINLESS-STEEL GRID
.INLESS-STEEL SCREEN
STAINLESS-^STEEL SCREEN
STAINLESS-STEEL GRID
-FILTER PAPER
Liquid Release Test Device
4-7
-------
PARTICLE SIZE ANALYSIS
Objectives
- range measurement
- distribution measurement
Significance
- treatabOity
- mixing
PARTICLE SIZE ANALYSIS
Continued
* Method
- sieve analysis
measures weight retained,
range: mm - 0.075 mm
MOISTURE CONTENT
Objectives
- determine the amount of free fluid
- determine soGds content
Significance
- process setection/compEance
- need of pretreatment
- mixing ratio selection
- field operations
Method
- ASTM D2216-80
- drying at 110 C
4-8
-------
BULK DENSITY
Objective
- determine weight to volume ratio
Significance
- weight to volume conversion (excavation,
treatment, shipping) and porosity
calculations
Methods
- drive cylinder (ASTM D2937-83)
- sand cone (ASTM D1556-82)
- nuclear (ASTM D2922-81)
- screening (ASTM D3402.025)
STRENGTH TESTING
Objective
- determine waste/son stability
Significance
- "trafficabifity" to construction
equipment
- "workability" - ease of processing
- S/S baseline
Methods
- Unconfined Compressive Strength
(UCS) (ASTM D2166-85)
- cone index (ASTM 3441-79)
PERMEABILITY
(Hydraulic Conductivity)
Objectives
- measure advective transport of water
through the waste
Significance
- affects migration of contaminants
- directly - flow rates
- indirectly - mechanisms of release
Methods
- ASTM 18.04 and D2434
- Army Corps of Engineers EM 1110-2-1906
4-9
-------
PERMEABILITY AND RELEASE
Concentration
(mg/L)
DARCY'S LAW:
q = ki A
q = Flow Rate
i = Hydraulic Gradient
A = Cross Section
k = Coefficient of Permeability
Ct - Steady State Concentration
q, - Actual Flow Rate
Contaminants Released
(mg/min)
Flow Rate (L/min)
PERMEABILITY FIELD TESTS
Falling head
Rising head
Constant head
Single well response
4-10
-------
WASTE CHARACTERIZATION
comostvrrY
Source: H*ndboofc ((K.StซMHZBHoA/SoHdirkซtlono
Hucrdow* .Wซat* EPA/S4O/2-afl/OO1
SITE CONsteEHATKJNS
1 pROPEirnea f~
1 PAGTReATUEHT
H . OB
| WAtfTE MIXING
OMTANCeS Tft
-flCCURE LANDFOJ.
-Aoomve eouRcca
REAGENT
ACQUISITION
AVALABLE
EOUPUEMT
nJLL-0CALE fXatOH
HN OflOM
-HH arm
-PIAHT UfXWQ
-AftEA MDMNO
QUALTTY CONTROL AHO
QUALITY ASSURANCE
SAFETY ANO
ENVIRONMENT
1
WASTE raocessMa AHO DISPOSAL U~
i
CLEANUP ANO CLOSURE
L
J
EVALUATING THE S/S PROCESS SELECTION
TREAT ABILITY STUDY STEPS
Mixing (ASTM C-305-82)
Compaction
- tamping
- shaker table
Molding
- cylinders
- cubes
Curing
- pozzolans
- cement
Parameters: temperature, humidity, time
4-11
-------
Interfering mechanism:
- adsorption (dicarboxylic acid)
- complexation (sucrose)
- precipitation
- nudeation (silica gel)
Accelerators:
- triethanolamine < 0.06 %
- calcium formate
INTERFERENCES
Continued
Retarders:
- formaldehyde
- oil and grease
- phenol
- sulfates
- metals (Pb, Cu, Zn)
PROCESS TESTING
Mixing properties
- heat of reaction
- alkalinity
- spiking
Strength development
Additive volume/weight control
4-12
-------
INTERRELATION OF PHYSICAL TESTS
Test Property Significance
Bulk density
Molstur* content
Wซt-dry rปซlซtanoป
Frซซzป-thaw r*tlซtanoซ
->-
>ป-
^^
^^
-^-
Volum* Increase
Porosity
Physical Integrity
Contact ar*a
^^ Landfill volume
requirement
containment
METHOD MODIFICATIONS
FOR TREATED WASTES
DCS - cylindrical vs cube samples
(D4633-84 vs C109-86)
method of pre- soaking
Permeability - flexible wan
permeameter
ADDITIONAL TESTS
FOR TREATED WASTES
True density/specific gravity
Solubility
Weathering properties
- wet dry (ASTM D-4843)
- freeze thaw (ASTM D-4842)
Biodegradation
- fungus (ASTM G21-70)
- bacteria (ASTM G22-76)
Micromorphology (LSU-WES-AEC)
4-13
-------
CALCULATED PROPERTIES
Weight change _ weight of treated waste
factor weight of. untreated waste
bulk density of
Volume change _ untreated waste weight change
factor bulk density of
treated waste
bulk density of
treated waste
Porosity = 1 : (1
true density of
treated waste
factor
- moisture content)
Nunber
20
COMPRESSIVE STRENGTH (UCS)
UCS (100 pdl
2468 29
15
10
5
0
Wastes No. 1-5
Total No. 67
30
20
10
2 4
UCS (1000 kPa)
20
PERMEABILITY
Mntor
IS
10
Wastes No. 3,4,5
Total No. 37
3
-4
Log
10
Decreashg penneafeity
40
30
20
10
0
4-14
-------
Properties are waste dependent
High UCS >
- good weathering durablty
Low UCS ^
- not conclusive
Freeze - Thaw Test
- more severe than Wet - Dry Test
VOLUME INCREASE
Wastes No. 1-5
Total No. 63
\A 1.8 Z2 18 3JD
Treated/raw waste vokme raSo
COMPUTED POROSITY
Nurto
Wastes No. 1-5
Total No. 69
DA OS OJS
Competed poroafty
4-15
-------
CHEMICAL TESTING METHODS
FOR DETERMINING EFFECTIVENESS
OF S/S PROCESSES
SECTION 5
Abstract
Slides
5-2
5-6
5-1
-------
CHEMICAL TESTING METHODS FOR DETERMINING EFFECTIVENESS OF S/S PROCESSES
Mr. Carlton Wiles Mr. Edwin Barth Dr. John Nobis
USEPA/RREL USEPA/RREL PEI Associates, Inc.
Cincinnati, Ohio Cincinnati, Ohio Cincinnati, Ohio
Chemical testing procedures applicable to raw or untreated hazardous
wastes may also have application to solidified/stabilized (S/S) wastes. This
presentation is devoted largely to a discussion of leaching tests since these
tests are most often used to evaluate the performance of S/S wastes as a
treatment process for hazardous wastes. Emphasis is on the appropriate
selection of the leaching tests and the interpretation of laboratory data.
The experimental conditions affecting reproducibility of laboratory data and
the limitations in extrapolating results to the field are discussed. At best,
laboratory leaching data can simulate the behavior of waste forms under
"ideal," static, or "worst-case" field conditions. Currently, leach tests are
used to compare the effectiveness of various S/S processes, but are not
verified to determine long-term Teachability of a waste.
The chemistry of the waste and the leaching solution defines the types and
kinetics of the chemical reactions that mobilize or demobilize contaminants in
the S/S waste. Reactions that can mobilize contaminants adsorbed or
precipitated within the waste form include dissolution and desorption. Under
nonequilibrium conditions, these reactions compete with demobilizing reactions
such as precipitation and adsorption. Nonequilibrium conditions generally
develop when a S/S waste is contacted by a leaching solution and can result in
a net transfer, or leaching, of contaminants into the leaching solution.
Extraction (or batch extraction) tests refer to a leaching test that
generally involves agitation of ground or pulverized waste forms in a leaching
solution. The leaching solution may be acidic or neutral. Also, it may vary
throughout the extraction tests. Extraction tests may involve one-time or
multiple extractions. In either case, leaching is assumed to reach
equilibrium by the end of one extraction period; therefore, extraction tests
are generally used to determine the maximum, or saturated, leachate
concentrations under a given set of test conditions.
Other types of leach tests involve no agitation. The leaching of
monolithic (instead of crushed) waste forms is evaluated in these tests.
Leaching may occur under static or dynamic conditions, depending on the
frequency of the leaching solution renewal. In static leach tests, the
leaching solution is not replaced by a fresh solution; therefore, leaching
takes place under static hydraulic conditions (low leaching velocities and
maximum leachate concentrations for monlithic waste forms). In dynamic leach
tests, the leaching solution is periodically replaced with new solution;
therefore, this test simulates the leaching of a monolithic waste form under
nonequilibrium conditions in which maximum saturation limits are not obtained
and leaching rates are high. "Static" and "dynamic," therefore, refer to the
velocity, not the chemistry of the leaching solution.
5-2
-------
Another key difference between these two leaching tests 1s that extraction
tests are short-term tests lasting from hours to days, whereas leach tests
generally take from weeks to months. Because of the crushed nature of the
waste and the larger amount of surface area available for leaching, extraction
tests (although short-term) are used to simulate "worst-case" leaching
conditions.
The following tests are discussed:
Tox1c1ty Characteristic Leaching Procedure (TCLP)
Extraction Procedure Toxlclty Test (EP Tox)
California Waste Extraction Test (Cal WET)
Multiple Extraction Procedure (MEP)
Monofllled Waste Extraction Procedure (MWEP)
Equilibrium Leach Test (ELT)
Add Neutralization Capacity (ANC)
Sequential Extraction Test (SET)
Sequential Chemical Extraction (SCE)
Materials Characterization Center Static Leach Test (MCC-1P)
American Nuclear Society Leach Test (ANS-16.1)
Dynamic Leach Test (DLT)
There are various experimental factors that effect laboratory results and
their Interpretations. These Included:
Sample nonhomogenelty
Curing time
Chemical type of leachant/exractant
Liquid to solid ratio
Extraction time
Particle size
Amount of oil and grease
The Impact of these and other experimental parameters must be considered
1n an evaluation of the results of several leaching tests on S/S wastes.
As mentioned previously, leaching tests produce results that are not
directly applicable to leaching behavior 1n the field. Nevertheless, the
results of several leaching tests or of leaching tests combined with physical
tests or microscopic techniques can be used as Indicators of field performance
and environmental Impact.
When used for comparative purposes, results from several leaching tests
can help to Identify field conditions that result 1n high concentrations of
waste constituents. Therefore, these data may be used to site or design waste
facilities that will minimize the leaching of hazardous constituents from the
wastes. The data also may be used to predict the leaching of S/S wastes at
different stages In time. For example, leaching conditions of a well-managed
operational facility where the monolithic S/S waste receives maximum
5-3
-------
precipitation infiltration may be simulated by the use of the DLT, as this
test involves constant renewal of the leaching solution and a monolithic waste
form. For a closed facility that has a cover which is maintained and
minimizes precipitation infiltration, leaching conditions may be similar to
those of the MCC-1P test (i.e., static hydraulic conditions). In the long
run, the liners, cover, and waste form may degrade, and leaching conditions
may be similar to those found in multiple extraction tests (such as MEP and
MWEP).
REFERENCES
1. U.S. Environmental Protection Agency. 1986. Test Methods for Evaluating
Solid Waste. Volumes 1A-1C: Laboratory Manual Physical/Chemical
Methods: and Volume II: Field Manuals, Physical/Chemical Methods,
SwW846, Third Edition, Office of Solid Waste. Document Control
No. 955-001-00000-1.
2. ASTM D1498-76, Standard Practice for Oxidation-Reduction Potential of
Water.
3. American Society for Testing and materials. 1981. Standard Methods for
Chemical Analysis of Hydraulic Cement, ASTM Committee C-l on Cement.
Philadelphia, Pennsylvania. July 1981.
4. U.S. Environmental Protection Agency. 1979. Methods for the Chemical
Analysis of Water and Wastes. Office of Research and Development.
EPA-600 4-79-020, March 1979.
5. Standard Methods for the Examination of Water and Wastewater, 16th
Edition, APR, AWWA, WPCF, 2985 Washington, D.C.
6. ASTM C186-86. Standard Test Method for Heat of Hydration of Hydraulic
Cement.
7. Bishop, P.L. 1986. Prediction of Heavy Metal Leaching Rates from
Stabilized/Solidified Hazardous Wastes. In Toxic and Hazardous Wastes
Proceedings of the 18th Mid-Atlantic Industrial Waste Conference.
8. American Nuclear Society (ANS). 1986. ANSI/ANS-16.1-1986 American
National Standard Measurement of the Leachability of Solidified Low-Level
Radioactive Wastes by a Short-Term Test Procedure. Prepared by the
American nuclear Society Standards Committee Working Group ANS-16.1.
Published by the American Nuclear Society, La Grange Park, Illinois.
Approved April 14, 1986, by the American National Standard Institute, Inc.
9. Bishop, P.L. 1988. Leaching of Inorganic Hazardous Constituents From
Stabilized/Solidified Hazardous Wastes. Hazardous Waste and Hazardous
Materials, 5(2):129-144.
5-4
-------
10. California Code, Title 22, Article 11. Criteria for Identification of
Hazardous and Extremely Hazardous Wastes, pp. 1800.75-1800.82.
11. Cote, P., and D.P. Hamilton. 1984. Leachability Comparison of Four
Hazardous Waste Solidification Processes. In: Proceedings of the 38th
Industrial Waste Conference, May 1983, Purdue University, West Lafayett,
IN.
12. Cote, P.L., and T.R. Bridle. 1987a. Long-Term Leaching Scenarios for
Cement-Based Waste Forms. Waste Management and Research, Vol. 5, pp.
55-66.
13. Cote, P.L., T.W. Constable, and A. Moreira. 1987b. An Evaluation of
Cement-Based Waste Forms Using the Results of Approximately Two Years of
Dynamic Leaching. Nuclear and Chemical Waste Management, Vol. 1, pp.
129-139.
14. Environment Canada and Alberta Environmental Center. 1986. Test Methods
for Solidified Waste Characterization.
15. Jones, L.W. 1986. Interference Mechanisms in Waste Stabilization/
Solidification Processes: Literature Review. Unpublished Report. U.S.
Environmental Protection Agency, Hazardous Waste Engineering Research
Laboratory, Cincinnati, Ohio.
16. U.S. Environmental Protection Agency, Generic Treatability Protocol for
Solidification/Stabilization Treatment for Contaminated Soils (1989)
17. U.S. Environmental Protection Agency. 1986b. Test Methods for Evaluating
Solid Waste, Method 9095, SW-846, Third Edition. November 1986.
18. U.S. Environmental Protection Agency. 1986. A Procedure for Estimating
Monofilled Solid Waste Leachate Composition. Technical Resource document
SW-924, 2nd Edition. Hazardous Waste Engineering Research Laboratory,
Office of Research and Development, Cincinnati, Ohio, and Office of Solid
Waste and Emergency Response, Washington, D.C.
19. U.S. Environmental Protection Agency. 1986g. SW-846 Test Methods for
Evaluating Solid Waste, Vol. 1C: Laboratory Manual Physical/Chemical
Methods, Third Edition. Office of Solid Waste and Emergency Response,
Washington, D.C.
20. U.S. EPA. 1988d. Evaluation of Test Protocols for Stabilization/
Solidification Technology Demonstrations. Revised Draft Report. U.S.
Environmental Protection Agency, Office of Research and Development,
Cincinnati, Ohio. Prepared by PRC Environmental Management, Inc. Contract
No. 68-03-3484, April 25, 1988.
21. Weitzman, L., L.E. Hamel, and E. Barth. 1988. Evaluation of
Solidification/Stabilization as a Best Demonstrated Available Technology.
Paper presented at 14th Annual Hazardous Waste Engineering Laboratory
Conference, Cincinnati, Ohio, May 1988.
5-5
-------
OVERVIEW OF CHEMICAL
TESTING SECTION
Theory of contaminant
migration
Review of chemical
testing procedures
Review leach data
LEACH TESTING
VS
EXTRACTION TESTING
LEACH TEST PURPOSE
Predict field performance
Accelerated leaching
- steady state vs rate
Comparison
5-6
-------
LEACH TEST VARIABLES
Monolith vs particles
Surface area
Liquid/solid ratio
Agitation vs static
Flow rate
Leachate composition
Temperature
LEACH TEST SCALE
Beaker
Column
Lysimeter
Groundwater collection system
LEACH TEST DEFINITIONS
Diffusion
Advection
Flux
Porosity
Tortuosity
5-1
-------
COMPARE LEACH RESULTS TO
Health based levels
Technology based levels
Dilution levels
Regulatory levels
% reduction
Different processes
LEACHING DATA
Leach Rate
L =
mass
(area) (time)
MODELLING S/S PERFORMANCE
Use data from multiple extract leach test
to estimate plume generation over time
5-i
-------
STEP 1 Obtain teach data (ANSI 16.1)
STEP 2 Pick's law model
STEP 3 Plot cumulative released vs. time
Determine release rale
STEP 4 hcorporate release rate into
saturated zone model (Wilson & Ivier)
-velocity
-aqufer thickness
-waste volume
-porosity
EXTRACTION TESTS
Refers to leaching tests involving
agitation of ground .waste with
extractant leaching solution
May involve one-time or multiple
extractions
Used to determine the maximum or
saturated leachate concentrations under
a given set of test conditions
EXTRACTION TESTS
Continued
Applicable to untreated hazardous
wastes
May also be applicable to organic
solidified/stabilized wastes
5-9
-------
TCLP
ANSI
MEP
ANC
OTHER
\/
\y
V
\/
\s
\/
V
LEACH TEST METHODS AND APPLICATIONS
TCLP (Toxic Characteristic Leaching Procedure)
EP TOX (Extraction Procedure Toxicity Test)
Cal WET (California Waste Extraction Test)
MEP (Multiple Extraction Procedure)
MWEP (Monofilled Waste Extraction Procedure)
LEACH TEST METHODS AND APPLICATIONS
Continued
ELT (Equilibrium Leach Test)
ANC (Acid Neutralization Capacity)
SET (Sequential Extraction Test)
SCE (Sequential Chemical Extraction)
5-10
-------
LEACH/EXTRACTION
TESTING
TCLP Grind to 9.5 mm sieve(.375 in)
Acetic acid(pH=3, 5)
TWA Hexane or MeCI digestion
ANSI 16.1 Distilled water renewal
No buffer
TOXIC CHARACTERISTIC LEACHING PROCEDURE
(TCLP)
Purpose - to determine amounts of
constituents available for leaching in
an acid medium (codisposal with
municipal waste)
TCLP CAGE MODIFICATION
Short-term tests to evaluate stability
or instability of S/S wastes
Requires tumbling a solid sample inside
of stainless steel cage that is inside
of TCLP extraction jar containing
leaching buffer
Well solidified wastes remain intact
and poorly solidified wastes are
significantly degraded
5-11
-------
SUMMARY PROCEDURAL DIFFERENCES
BETWEEN TCLP AND EP TOX
Experimental
Parameter
Filter size.
1x10'6m
Filter pressure,
psi
Leaching solution
Period of
extraction, H
Liquid/solid ratio
TCLP
0.6-0.8
50
Acetate
buffered,
pH approx. 3 or 5
18
20:1
EP TOX
0.45
75
Acetic
acid.
pH approx. 5
24
16:1
MULTIPLE EXTRACTION PROCEDURE
(MEP)
Used for delisting
Multiple extractions - usually nine, but
more possible if last three do not
decrease leachate concentrations
ซ Results used to determine maximum
leachate concentrations
Results used with EP Tox to compare
leachability of hazardous constituents
under mild and acidic conditions
CALIFORNIA WASTE EXTRACTION TEST
(Cal WET)
Differs from the TCLP and EP TOX in the
following parameters:
- different leaching solution (sodium citrate
buffered solution at pH of 5; or, for
hexavalent chromium, distilled water)
- smaller liquid to solid ratio (10:1)
- smaller particle size (< 2.0 mm)
- longer extraction period (48 hrs.)
5-12
-------
ANSI 16.1
Infinite leachant
(5 day, 90 day)
QC
Indicator of performance
with model
Utilized by NRC
ANS-16.1 PROCEDURE
Monolithic cylinder (length:diameter 0.2-5.0)
Leached with distilled water at V/S ratio of
10 cm at ambient temperature
Rinse sample to zero contamination at
surface
Immerse in water which is replaced after
2, 7. 24. 48, 72 hrs.. and then 4, 5, 14.
28. 43. 90 days
PSA MODIFIED ANSI/ANS-16.1
LEACH METHOD
Developed to deal with specific sample
preparation & handling required by soft &
porous waste forms from hydraulic binders, e.g.
cements, pozzolans, gypsums, phosphates, etc.
Changes made in (1) specimen preparation &
handling. (2) site-specific leachant, (3) vessel
material & cleaning procedure, (4) leachate
handling & stabilization. (5) variable length
leach intervals, & (6) statistical design
5-13
-------
DYNAMIC LEACH TEST
(DLT)
Modified version of ANS-16.1 which renews
leaching solutions more frequently and
changes V/S ratio
Results on cement containing heavy metals
show that Leachate Index (LX) values vary
within 1 unit
Organic compounds have LX values between
5-10 (higher leach rates) and metals
higher (slower rates)
MATERIALS CHARACTERIZATION CENTER
STATIC LEACHING TEST (MCC-1P)
Static leaching test developed for high-
level radioactive waste
Involves leaching monolith with water at ratio
of leaching solution to surface area solids
(V/S) of 10 - 200 cm
Period and temperature of extraction may vary
Used for organic and polymer S/S processes
MONOFILL WASTE EXTRACTION PROCEDURE
(MWEP)
Formerly Solid Waste Leach Test (SWLT)
Involves multiple extractions of a
monolith or crushed waste with water
Used to derive reasonable leachate
compositions in monofilled disposal
facilities
5-14
-------
ACID NEUTRALIZATION CAPACITY
(ANC)
Continued
Test used to determine buffering capacity of
solidified/stabilized waste form
The higher the buffering capacity of the waste,
the greater the possibility of maintaining
alkaline conditions and minimizing the amount of
metals leached
NOTE:
PC - Portland Cement
KD - Kiln Dust
LF - Lime/Flyash
PHASE I SARA BOAT PROGRAM
Synthetic Soil III
Metal
As
cd
Or
Cu
PD
Ni
Zn
Raw
TWA
690
2380
1260
3550
15100
1540
34450
Raw
TCLP
6.99
33.1
ND
80,7
19.9
17.5
359
Treated
TCLP
ND
ND
.07
.09
ND
ND
0.69
% Removal
100
100
increase
100
100
100
100
Binder
PC
PC.KD
PC.KD.LF
PC
PC
PC
PC
PHASE
1 SARA
BOAT
Synthetic Soil
Metal
As
Cd
Cr
Cu
Pb
Ni
Zn
Raw
TWA
940
3790
1400
11250
15680
1550
28660
Raw Treated
TCLP TCLP
9.58
35.3
.06
10.0
70.4
26.8
336
ND
ND
.07
0.17
0.37
ND
0.74
PROGRAM
IV
X Removal
100
100
increase
100
99
100
100
Binder
PC
PC,KD,LF
PC,KD,LF
PC
PC
PC,KD,LF
PC
5-15
-------
OKLAHOMA SITE
TCLP Results
Volatiles
Benzene
Ethyl Benzene
Toluene
Untreated
ND-TR
ND-TR
TR-0.027
Treated
ND
ND
ND
FLORIDA SITE
Treated Waste ppm
MCC ANS 16.1 EP Tox OILY EP
Lead 0.09 0.09
0.4
61
PCBs 0.001 0.001 N/A N/A
FIGURE 1. CHROMIUM LEACH CONCENTRATIONS
Chrot
Coon
fppn
2r
1.5 -
1
0.5
oL
Bfam DURING MEP TEST
fltfSaOO
L L, ., B.,, m- m m m
0123456769
Extraction test run
B 0.15 B/A ratio ฎ 0.75 B/A ratio
5-16
-------
ORGANOPHILIC CLAY RESULTS
B\s (2-chloro 8528 ND
isopropyl ether)
Naphthalene 18060 1445
Phenanthrene 20184 ND
Benzo (A) 30460 ND
anthracene
ND
ND
ND
ND
CONCLUSIONS
Leaching tests not directly applicable
to leaching in the field
Results of several leaching tests
and some physical tests can be
used as indicators of field performance
Data may be used to design waste
facilities that will minimize the
leaching of hazardous constituents
Data may also assist in predicting
the leaching of S/S wastes at
different stages in time
5-17
-------
/
TECHNOLOGY SCREENING PROCEDURES
FOR DETERMINING IF S/S
SHOULD BE IMPLEMENTED
SECTION 6
Abstract 6-2
Slides 6-4
6-1
-------
TECHNOLOGY SCREENING PROCEDURES FOR DETERMINING
IF S/S SHOULD BE IMPLEMENTED
Dr. Leo Weitzman Mr. Jesse Conner
LVW Chemical Waste Management
Durham, North Carolina Riverdale, Illinois
The decision on whether to use S/S, another technology or a combination
of technologies at a site requires the evaluation of fundamental concepts,
experience and the results of laboratory and pilot-scale tests. This
section presents a series of steps to be taken in the selection process. It
discusses the following factors and their interrelations:
1. Waste Characteristics
2. Technology/Binder Selection
3. Pretreatment Requirements
4. Site Characteristics
5. "Product" Acceptability Tests
6. The Iterative Nature of the Screening Process
This discussion builds on the concepts described in the earlier section,
"Description of S/S Technologies." It combines the concepts with empirical
results obtained in the past and gives guidelines for how one should set up
a screening program appropriate to a specific waste/site problem.
REFERENCES
Chemical Rubber Publishing Company, Handbook of Chemistry and Physics 41st
Edition, 1960.
Pauling, L. General Chemistry, second edition, W.H. Freeman & Co.
San Francisco, CA, 1953.
Rowe, G. Evaluation of Treatment Technologies for Listed Petroleum Refinery
Wastes Report prepared for The American Petroleum Institute Technology Task
Force, American Petroleum Institute, Washington, DC, December, 1987.
Cullinane, J.M., Jones, L.W., Handbook for Solidification/Stabilization of
Hazardous Wastes Final Report, Interagency agreement AD-96-F-2-A145 between
the EPA and the U.S. Army Corp. of Engineers, Waterways Experimental
Station, Vicksburg, MI, 1989.
Weitzman, L., Hamel, L.R., Cadmus, S.R. Volatile Emissions from Hazardous
Waste Final Report Prepared for the U.S. Environmental Protection Agency,
Risk Reduction Engineering Laboratory, Contract 68-02-3993, WA 32, 34.
Weitzman, L., Hamel, L.R., Cadmus, S.R. Evaluation of Solidification/
Stabilization as a BOAT for Superfund Soils. Final Report prepared for
Environmental Protection Agency, Risk Reduction Engineering Laboratory,
Contract 68-03-3241, WD-18, 1988.
6-2
-------
Environmental Protection Agency, Review of In-Pi ace Treatment Techniques for
Contaminated Surface Soils. EPA-540/2-84-003a, Sept, 1984.
Kyles, O.H., Malinowski, K.C., Stanczyk, T.F. Solidification/Stabi1ization
of Hazardous Haste. A Comparison of Conventional and Novel Methods. Toxic
and Hazardous Waste, Proceedings of the Ninteenth Mid-Atlantic Industrial
Waste Conference, Technomic Publishing Co. Lancaster, PA, 1987.
Wiles, C.C. A Review of Solidification/Stabilization Technology. Journal of
Hazardous Materials, 14(1987)5-21, Also available as EPA/600/J-87/019
Stabilization/Solidification of CERCLA and RCRA Wastes. PEI Associates and
Earth Technology Corporation, EPA/May 1988.
6-3
-------
GOALS OF TECHNOLOGY SCREENING
1. To determine suitability and likelihood
of success of immobilization
2. To select appropriate immobilization
technologies
a. for RCRA TSD facilities
b. for CERCLA remediations
(and RCRA corrective actions)
WHAT DOES GOAL NO. 1 REALLY MEAN?
In the broadest sense EVERY WASTE
Is potentially suitable for
immobilization
BOTH SUITABILITY AND LIKELIHOOD
OF SUCCESS DEPEND UPON
Matching the waste to appropriate
immobilization technologies
Matching each technology's needs (along
with the waste's characterization) to
appropriate pretreatment requirements
6-4
-------
SCREENING
Comparing waste characteristics to technology
capabilities Is NOT a "one-time" operation
It Is reiterated (at greater depth)
throughout the technology selection
process at such stages as
- "conceptual" screening
- detailed screening
- feasibility study
- process design
EVALUATION MO SELECTION OF ^MOBILIZATION
FOR SITE REMEDIATION (CERCLA or RCRA C. A.)
| Wait* Characterization ]
Chemical
- constituents
- hazard
1
Physical
-form
- phat*
1
It Immobilization
wtth protroataMiit
appltoablo
6-5
-------
IMPORTANT WASTE CHARACTERISTICS
Chemical Composition
(Concentration & toxicity of each constituent)
Organic components
- polar, nonpolar
- volatile, semivolatile, nonvolatile
Inorganics
- acids
- oxidizers
- metals
- soluble salts
IMPORTANT WASTE CHARACTERISTICS
Physical Characteristics
Phase & form (liquid, solid,
sludge, soils)
Total solids
Particle size distribution
Presence of debris
How do we match waste characteristics
to potential Immobilization technologies?
6-6
-------
IMMOBILIZATION TECHNIQUES
* Cement based binders
- Portland cement
- cement kiln dust
natural and artificial pozzolans
- cement/flyash
* Lime/limestone/quicklime
- lime kiln dust
- fime/flyash
* Absorbents
- hydro- and organo-philic clays
- wood chips, etc., generally not acceptable
(1 of 2)
IMMOBILIZATION TECHNIQUES
Thermoplastic binders
- asphalt/bitumen
- thermoplastic polymers
Thermosetting polymeric binders
* Vitrification
(2 of 2)
COMPATIBILITY OF WASTE TYPES
vs. IMMOBILIZATION METHOD
Waste Component Cement-Based S/S
Inorganics
- acid wastes
- oxidizers
- sulfates
- halides
- heavy metals
- radiaoactive
materials
Cement will neutralize acids
compatible
may retard setting
easily leached,
may retard setting
compatible
compatible
6-7
-------
COMPATIBILITY OF WASTE TYPES
vs. IMMOBILIZATION METHOD
Waste Component Lime-Based S/S
Inorganics
- acid wastes
- oxidizers
- sulfates
- halides
- heavy metals
- radiaoactive
materials
compatible
compatible
compatible
easily leached,
may retard setting
compatible
compatible
COMPATIBILITY OF WASTE TYPES'
vs. IMMOBILIZATION METHOD
Waste Component Thermoplastic solidification
(little data available)
should be neutralized
before incorporation
may cause matrix
breakdown: fire
may dehydrate and
rehydrate causing splitting
may dehydrate
compatible
compatible
Inorganics
- acid wastes
- oxidizers
- sulfates
- haJides
- heavy metals
- radiaoactive
materials
COMPATIBILITY OF WASTE TYPES
vs. IMMOBILIZATION METHOD
Waste Component
Inorganics
- acid wastes
- oxidizers
- sulfates
- halides
- heavy metals
- radiaoactive
materials
Thermosettlng Polymers
(little data available)
compatible
may cause matrix
breakdown
compatible
compatible
acid pH solubilizes metal
hydroxides
compatible
6-8
-------
COMPATIBILITY OF WASTE TYPES
vs. IMMOBILIZATION METHOD
Waste Component Vitrification
Inorganics
- acid wastes
- oxidizers
- aulfates
- halides
- heavy metals
- radiaoactive
materials
should first be neutralized
will react in process
compatible
fluorine-silicate interactions
possible (defluorination
as pretreatment)
compatible
compatible
COMPATIBILITY OF WASTE TYPES
vs. IMMOBILIZATION METHOD
Waste Component Cement-Based S/S
Organics
- nonpolar
- polar
impedes setting, volatiles
will escape in processing
may significantly retard
settjng. decreases durability
Generally, organics should be removed or destroyed
as "pretreatment" before cement-based S/S
COMPATIBILITY OF WASTE TYPES
vs. IMMOBILIZATION METHOD
Waste Component Lime-Based S/S
Organics'
- nonpolar
- polar
impedes setting, decreases
durability, volatiles may
escape
phenols and alcohols retard
setting, decreases durability
Generally, organics should be removed or destroyed
as "pretreatment" before lime-based S/S
6-9
-------
COMPATIBILITY OF WASTE TYPES
vs. IMMOBILIZATION METHOD
Waste Component Thermoplastic Solidification
Organics
- nonpolar
- polar
compatible, may vaporize
upon heating
compatible, may vaporize
upon heating
COMPATIBILITY OF WASTE TYPES
vs. IMMOBILIZATION METHOD
Waste Component Thermosettlng polymers
Organics
- nonpolar
- polar
may impede setting
compatible
COMPATIBILITY OF WASTE TYPES
vs. IMMOBILIZATION METHOD
Waste Component Vitrification
Organics"
- nonpolar
polar
will volatilize,
will combust if oxygen
is available
will volatilize.
will combust if oxygen
is available
Vitrification of residues as part of an organics
incineration scheme is often proposed
6-10
-------
COMPATIBILITY OF PHYSICAL CHARACTERISTICS
vs. IMMOBILIZATION METHOD
Waste Component
Phase or Form
- liquid
- sludge
- solid
- contaminated soil
- total solids
particle size dist.
Presence of debris
Cement-Based Binders
acceptable
acceptable (pumping
concerns)
acceptable (mixing
concerns), solids must be
wettable
acceptable
any range
prefer smaller size and
random distribution
must be removed
COMPATIBILITY OF PHYSICAL CHARACTERISTICS
vs. IMMOBILIZATION METHOD
Waste Component
Phase or Form
- liquid
- sludge
- solid
- contaminated soil
- total solids
- particle size dist.
- Presence of debris
Lime-Based Binders
acceptable
acceptable (pumping
concerns)
acceptable (mixing &
wetting concerns)
acceptable
any range (0-100%)
prefer smaller size and
random distribution
must be removed
COMPATIBILITY OF PHYSICAL CHARACTERISTICS
vs. IMMOBILIZATION METHOD
Waste Component
Phase or Form
- liquid
- sludge
- solid
- contaminated soil
- total solids
- particle size dist.
Thermoplastic
aqueous liquids not applicable
water evaporated in process
acceptable
acceptable
10-100X
smaller size preferred
- Presence of debris must be removed
5-11
-------
COMPATIBILITY OF PHYSICAL CHARACTERISTICS
vs. IMMOBILIZATION METHOD
Waste Component
Phase or Form
- liquid
- sludge
- solid
- contaminated soil
- total solids
- particle size dist.
- Presence of debris
Thermosetting polymers
information lacking
COMPATIBILITY OF PHYSICAL CHARACTERISTICS
vs. IMMOBILIZATION METHOD
Waste Component
Phase or Form
- liquid
- sludge
- solid
- contaminated soil
- total solids
- particle size dist.
- Presence of debris
Vitrification
not applicable
deyvatering required
acceptable
acceptable
40X - 100X
in reactor - solids should
be crushed
in situ - no restrictions
in reactor - remove debris
in situ - no metallic debris
> 0.9 X electrode spacing
INTERFERENCES TO CHEMICAL S/S SYSTEMS
Sulfur
* Calcium chloride
Sodium arsenate
Sodium borate
* Sodium phosphate
Sodium halides
Soluble metal salts
- tin. zinc, copper, lead
6-12
-------
MANIFESTATIONS OF INTERFERING
CONSTITUENTS
Spelling and cracking
Set retardation: hardening and
waste containment are impeded
Flash set; mixing incomplete
as a result of quick set.
equipment can be fouled
(1 of 2)
MANIFESTATIONS OF INTERFERING
CONSTITUENTS
Chelated/complexed toxic constituents
may accelerate leaching, even if
waste is successfully S/S
Some waste constituents can react and
cause swelling and disintegration of S/S
mass long after setting reactions complete
Oxidizers can cause slow deterioration of
the organic binder matrix
(2 of 2)
INTERACTIONS BETWEEN S/S BINDERS AND SPECIFIC ORGANICS
Portland Cement_
Organic Compounds Type 1 Type II & IV
Alcohols & Glycols Durability: decrease Durability: decrease
Aliphatic it Aromatic Set time: Increase Set time: Increase
Hydrocarbons Durability: no effect
Chlorinated
Set time: Increase Set time: Increase
Durability: decrease Durability: decrease
Clay-Cement
Durability: decrease
Data unavailable
Data unavailable
6-13
-------
INTERACTIONS BETHEEN S/S BINDERS AND SPECIFIC INORGANICS
Portland Cement
Chemical Group
Heavy Metal
Salts & Complexes
Inorganic Adds
Inorganic Bases
Type 1
Set time: Increase
Durability: decrease
Set time: no effect
Durability: decrease
Set time: no effect
Type II & IV
Set time: Increase
Durability: no change
Set no effect
Durability: no effect
Set time: no effect
Durability: no effect Durability: no effect
Durability (decreases
with KOH & NaOH)
Clav-Cement
Set time: Increase
Durability: decrease
Durability: decrease
Durability: decrease
In general, one or more methods of
immobilization will be good candidates
as part of an Integrated process
for ANY waste.
GOALS OF TECHNOLOGY SCREENING
1. To determine suitability and likelihood
of success of immobilization
2. To select appropriate immobilization
technologies
a. for RCRA TSD facilities
b. for CERCLA remediations
(and RCRA corrective actions)
6-14
-------
DIFFERENCE BETWEEN GOALS 2a AND 2b
RCRA treatment facilities will be driven by
the,regulations and by the technology
they have available in their facility
RCRA land disposal facilities will be
driven by regulations
Remediation actions will have the full
set of technologies as options
Remedial actions will be driven by site
characteristics and regulatory and
institutional restrictions as well as
waste characteristics
GOALS OF TECHNOLOGY SCREENING
1. To determine suitability and likelihood
of success of immobilization
2. To select appropriate immobilization
technologies
a. for RCRA TSD facilities I
b. for CERCLA remediations
(and RCRA corrective actions)
Any one treatment facility will probably
have one (or a few) specific Immobilization
technologies In place
and
will have a limited menu of
pretreatment options available
6-15
-------
- AND SO -
"Screening" at a RCRA TSD Facility means
determinig whether each proposed
waste is treatable by that
immobilization technology
TSD
Treatment, Storage, and Disposal of
hazardous wastes under the Resource
Conservation and Recovery Act (RCRA) and
subsequent amendments. A unit or facility
which disposes of RCRA wastes at the
facility may also be referred to as a
"secure landfill" or "minimum technology unit"
SCREENING CONCERNS
Treatment vs. Disposal Facilities
Treatment question - can "this" waste be
treated to be acceptable for disposal
Disposal question - can "that" material
pass all the required tests for
acceptance here
6-16
-------
SELECTION FACTORS INVOLVED IN
THE USE OF S/S AT A TSD FACILITY
Regulations
Waste Characteristics
Operational and Economic Factors
Site Methodology
Test Methods
S/S DECISION TREE AT A RCRA TSD FACLTTY
Protroatmont (dowatorlng, phaao
aoparatlon, tr**h removal, etc.)
S/S aoreenmg teata
Pซซt teata
redo
rejeot
Optlmlz* formulation
Continuing QA/QC for product
DETERMINING F S/S IS APPLICABLE
AT A RCRA TSD FACBJTY
f
Waetซ
Bannod undor anothor
regulatory eyatem, e.g. TSCA?
Not aultablo
for S/S
yoa
Bannod undor landbana
Not eovorod yot or oxtondod
undor tho landbana
yoa
Generator certified aa
meeting landban requirement*
Restricted or banned under
atto permit oondltlona
Othorwlao unacceptable
to TSD facility
yoa
|no
Non-S/8 technology
or treatment-train required
c.
'**ป
Requlrea addtl
treatment flrat
Then S/S
Potentially editable
for S/S
yoa
6-17
-------
SELECTION FACTORS INVOLVED IN
THE USE OF S/S AT A TSD FACILITY
Regulations
Waste Characteristics
Operational and Economic Factors
Site Methodology
Test Methods
REGULATIONS AFFECTING DISPOSAL
Landbans
Permit Conditions
TSD Conditions
Other Regulatory Systems
REGULATIONS AFFECTING DISPOSAL
Landbans
Liquid-in-Landfill Ban
Solvent Ban
California List Ban
Scheduled Wastes
- First Third
- Second Third
- Third Third
- Soft-Hammer
- Extensions
6-18
-------
REGULATORY LEVELS IN LEACHATES
AFTER 2nd 3rd LANDBAN
(July 1989)
Concentration of Constituent (mg/l)
in Waste or Leachate
Description] As
Lowest level in
any 1st3rd
waste code
Delisting
levels
RCRA
Characteristic
levels
Drinking
water stds.
0.004
0.315
5.000
0.050
Ba
6.900
100.0
1.000
Cd
0.066
0.063
1.000
0.010
Cr
0.084
0.315
5.000
0.050
Pb
0.180
0.315
5.000
0.050
Hg
0.025
0.013
0.200
0.002
Ni
0.048
3.150
2.205
Se
0.025
0.063
1.000
0.010
Ag
0.072
0.315
5.000
0.050
REGULATIONS AFFECTING DISPOSAL
Permit Conditions
EPA Region
State
6-19
-------
REGULATIONS AFFECTING DISPOSAL
TSD Conditions
Company Policy
Protection of Landfill Liners
REGULATIONS AFFECTING DISPOSAL
Other Regulatory Systems
TSCA: PCBs
6-20
-------
SELECTION FACTORS INVOLVED IN
THE USE OF S/S AT A TSD FACILITY
Regulations
Waste Characteristics
Operational and Economic Factors
Site Methodology
Test Methods
SELECTION FACTORS INVOLVED IN
THE USE OF S/S AT A TSD FACILITY
Waste Characteristics
Chemical Characteristics
- Metal Content
- Metal Speciation
- Reactivity
- Presence of Cyanide or Sulfide
(1 of 2)
SELECTION FACTORS INVOLVED IN
THE USE OF S/S AT A TSD FACILITY
Waste Characteristics
Chemical Characteristics
- Corrosivity
- Ignitability
- Organic content
- Non-toxic Organics
- Toxic organics
- Volatile organics
- Radioactivity
(2 of 2)
6-21
-------
SELECTION FACTORS INVOLVED IN
THE USE OF S/S AT A TSD FACILITY
Waste Characteristics
(Physical)
Total solids
Viscosity
Particle size distribution
Phase separation
Physical state
(1 of 2)
SELECTION FACTORS INVOLVED IN
THE USE OF S/S AT A TSD FACILITY
Waste Characteristics
(Physical)
Dustiness. Odor
Organic emissions
Trash content
(2 of 2)
SELECTION FACTORS INVOLVED IN
THE USE OF S/S AT A TSD FACILITY
Regulations
Waste Characteristics
Operational and Economic Factors
Site Methodology
Test Methods
6-22
-------
SELECTION FACTORS INVOLVED IN
THE USE OF S/S AT A TSD FACILITY
Operational and Economic Factors
Availability and cost of binders
Quality and consistency of binders
Pretreatment requirements
Materials handling
Volume and weight increase
SELECTION FACTORS INVOLVED IN
THE USE OF S/S AT A TSD FACILITY
Regulations
Waste Characteristics
Operational and Economic Factors
Site Methodology
Test Methods
SELECTION FACTORS INVOLVED IN
THE USE OF S/S AT A TSD FACILITY
Site Methodology
Waste profile
Acceptance test on sales sample
Fingerprint of received waste
QC/QA on continuing basis
- Sampling procedure
- Sampling frequency
6-23
-------
SELECTION FACTORS INVOLVED IN
THE USE OF S/S AT A TSD FACILITY
Regulations
Waste Characteristics
Operational and Economic Factors
Site Methodology
Test Methods
DETERMINING FACTORS IN THE ACCEPTABILITY
OF "IMMOBILIZED" WASTE AT A TSD FACILITY
Test Methods
Paint Filter Test (PFT)
Toxicity Characteristic
Leaching Procedure (TCLP)
Site specific tests
- Screens for:
- Ignitability
- Corrosivity
- Reactivity
- Radioactivity
GOALS OF TECHNOLOGY SCREENING
1. To determine suitability and likelihood
of success of immobilization
2. To select appropriate immobilization
technologies
a. for RCRA TSD facilities
b. for CERCLA remediations
(and RCRA corrective actions)
6-24
-------
EVALUATION AND SELECTION OF IMMOBILIZATION
FOR SITE REMEDIATION (CERCLA or RCRA C.A.)
Consideration of Remedial Action Alternatives
Selection of candidates based on
evaluation of site ft waste characteristics
Immobilization selected
alternate technology
selected
- Economic considerations
Regulatory considerations
Sociological considerations
Treatablllty/acreenlng testing
*
Selection of process
ft
Development of specifications
testing
look for alternate technology r^4~
Site Considerations
Geological ft
hydrologies! setting
Logistics
Climate
Consideration of candidate
remediation technologies
I
to S/S feasible?
Can site modifications
be made for S/S
yes
Is waste on site
treatable by S/S
ves
+ 1 t
Select alternate
technology
Proceed to
troatabmty/screenlmj
studies
6-25
-------
FULL SCALE PROCESS DESIGN
CERCLA Sites
R*ag*nt acquisition
AvallBbl* equipment
FACTORS IN SELECTING AN
IMMOBILIZATION PROCESS/SYSTEM
Waste characteristics
Immobilization technology
Site characteristics
- water table
- climate
- soil characteristics
- site layout
- logistics
- other
SITE CHARACTERISTICS
Will Limit:
Immobilization technology chosen
Pretreatments used
(further limiting technologies)
The full-scale design process
Final specifications imposed on the
immobilized product to be disposed
- if on site, spec's determined for
each site
- if off site, spec's same as TSD
6-26
-------
SITE CONSIDERATIONS
* Water table
Climate
Soil characteristics
Site layout
Logistics
Other
WATER TABLE & CLIMATE
Questions to be Answered First
Does immobilization require engineered
controls to allow implementation and
placement on site
Will immobilized material be disposed
off site
WATER TABLE/RAINFALL
Wetter Engineered controls needed Drier
<
for on-site disposal
Higher Cost of on-site disposal Lower
Note: On site means at the CERCLA remedial site
Off site means final disposal at another location
6-27
-------
ENGINEERED CONTROLS
Dikes
Berms
Groundwater diversion
Liners: grout curtains
Waste isolation
SITE CONSIDERATIONS
Water table
Climate
Soil characteristics
Site layout
Logistics
Other
Porous,
Sandy
Higher
Note: On
Off
SOIL TYPE
Clay,
Engineered controls needed Impervious
for on-site disposal
Cost of on-site disposal
site means at the CERCLA remedial
site means final disposal at another
Lower
site
location
6-28
-------
SITE CONSIDERATIONS
Water table
Climate
Soil characteristics
Site layout
Logistics
Other
SITE LAYOUT CONCERNS
Available area
Staging/storage space
Topography
- grading
- drainage concerns
Proximity of neighbors
- noise
- blowing dust
- odors/ volatiles emission
SITE CONSIDERATIONS
Water table
Climate
Soil characteristics
Site layout
[ Logistics
Other
6-29
-------
LOGISTIC CONCERNS
Available access
- equipment
- binder material delivery
Proximity to suppliers
Proximity to disposal facility
(if immobilized product is to be
disposed off site)
Contention of Remedial Action Alternatives
TREAT ABILITY STUDY TO SELECT S/S
BINDER SYSTEM
Sampling program
Analytical program
Binder screening
Binder quantity determination
- S/S product performance
- Criteria for success
QA/QC for all steps
Moatlon of candidate* baซ*d on
evaluation of site & waete characteristics
Immobilization selected
alternate toohnology
aoloetod
Eoonomlo considerations -
Regulatory considerations -
Soolologloal considerations -
yes
I Treatabllity/screenlng testing ;
I
Selection of process
&
Development of specifications
pilot
testing
look for alternate technology p
6-30
-------
SAMPLING PROGRAM
Waste characteristics
Soil characteristics
Site characteristics
Specific considerations noted
ANALYTICAL PROGRAM
What tests/ measurements?
Accuracy* reproducibility
How many measurements necessary?
-statistics
TREATABILITY STUDY TO SELECT S/S
BINDER SYSTEM
Sampling program
Analytical program
Binder screening
Binder quantity determination
- S/S product perfromance
- Criteria for success
QA/QC for all steps
6-31
-------
SCREENING OF BINDER SYSTEM
Which candidate systems meet
physical requirements
Which candidate systems meet
chemical (leaching) requirements
PHYSICAL SCREENING
Will the binder/waste matrix harden?
- penetrometer
- UCS
- visual
CHEMICAL (LEACHING) SCREENING
Will the binder/waste matrix
pass applicable tests
- EP toxicity
- TCLP
- ANS 16.1
- WET
- etc.
6-32
-------
TREATABILITY STUDY TO SELECT S/S
BINDER SYSTEM
Sampling program
Analytical program
Binder screening
Binder quantity determination
- S/S product perfromance
- Criteria for success
QA/QC for all steps
BINDER QUANTITY DETERMINATION
Set up screening tests at varying
ratios of:
- binder to contaminated soil or waste
- water to binder, or water to solids
Measure performance at each condition
EXAMPLE
Screening tests
- binder-waste (B/W) 0.1. 0.5. 1.O..
- watensolids (W/S) 0.5, 0.7. 1.0,.,,
* Will it harden in 24 hours
- UCS
- penetrometer
- visual
6-33
-------
Within general ranges of system selected
prepare a large number of samples
for further testing
CHEMICAL SCREENING TEST
Using the lowest addition that hardened
to selected criteria
TCLP
EP toxicity
MEP
ANSI 16.1
WHAT RATIO WILL HARDEN
IN 24 HOURS?
0.1
0.5
0.5
0.7
1.0
0.7
' - No. of samples
Test for hardness at 24 hours
Will give a broad range for more specific testing
6-34
-------
NARROW RANGE FOR TESTING
BASED ON SCREENING RESULTS
\w/s
B/W\
0.2
0.3
0.4
0.5
0.5
X
X
X
X
0.6
X
X
X
X
0.7
X
X
X
X
TREAT ABILITY STUDY TO SELECT S/S
BINDER SYSTEM
Sampling program
Analytical program
Binder screening
Binder quantity determination
- S/S product perfromance
- Criteria for success
QA/QC for all steps
Regulatory guidance on product "specification"
(e.g. leaching standards, performance
criteria, etc.) are not yet "set in concrete".
So we must consider other regulatory
guidelines
6-35
-------
LEACHING STANDARDS
(mgs/L)
Arsenic
Barium
Cadmium
Chromium
Lead
E.P. TOX
Characteristic
5.0
100.0
1.0
5.0
5.0
(MEP &
others )
Delisting
0.315
6.3
0.063
0.315
0.315
Landban
F006
0.066
5.2
0.51
(TCLP)
K061
0.14
5.2
0.24
LEACHING STANDARDS FOR ORGANICS
(mgs/L)
HW No.
D019
D021
D022
Contaminant
Benzene
Carbon Disulfide
Regulatory level
0.07
14.4
Carbon Tetrachloride 0.07
Tentative OAQPS tests for
air emissions
6-36
-------
CONCLUSION
In general, one or more methods of
immobilization will be good candidates
as part of an integrated treatment
process for ANY waste
But you must match the waste to
the technology & select apptopriate
pretreatments
6-37
-------
FIELD IMPLEMENTATION PROCEDURES
UTILIZED FOR S/S
SECTION 7
Abstract 7-2
Slides 7-6
7-1
-------
FIELD IMPLEMENTATION PROCEDURES UTILIZED
FOR STABILIZATION/SOLIDIFICATION
Mr. Richard McCandless Mr. Peter Hannak Mr. Robert Maxey
UC/Center Hill Lab CH2M Hill The Earth Technology Corp.
Cincinnati, Ohio Waterloo, Ontario Alexandria, Virginia
There are usually six functions which must be satisfied for the successful
implementation of a stabilization/solidification project. They are:
Waste removal
Untreated waste transportation
Chemical reagent storage
Waste/reagent mixing
Stabilized/solidified waste transportation
Stabilized/solidified waste replacement
In addition, waste may have to be stockpiled, moved or further processed
in pretreatment operations such as dewatering or neutralization. Some
processes may not require all of the steps, such as in-situ stabilization/
solidification where the reagent is brought to the waste and it is
stabilized/solidified in place.
Waste Removal
Due to the large quantities of waste which are usually stabilized/
solidified, waste removal has generally been accomplished by the use of
traditional earth-moving equipment. This equipment includes tracked backhoes,
draglines, bulldozers and front-end loaders. This equipment has been In use
for many years in the construction industry. Thus, its application to
hazardous waste use is merely one of adaptation. The physical state of the
waste may indicate the sequencing of operations necessary for the site. For
example, the presence of a liquid above the waste can be managed by removal of
this supernatant and treatment as a separate waste. The safety aspects of the
waste relate to the equipment operators and other workers. Complete enclosure
of the operator space in construction equipment and the provision of breathing
air may be necessary.
Tracked backhoes and draglines are used for the remote removal of
materials. Typically a backhoe is used in cases where use of equipment In an
area is prevented for reasons of soil stability. Backhoe operations can occur
in hazardous waste sludges which ordinarily would not support equipment. The
rate at which waste is removed needs to be assessed in order that rates of
material removal and transportation be as evenly matched as possible.
Draglines have application where reaches longer than 40 feet are
necessary. They are delivered to a site in pieces, usually by truck, and
assembled. This delivery and assembly needs to be taken into consideration as
they can consume many days' time. Draglines cannot provide removals more
7-2
-------
accurately than a couple of feet.
during dragline operation.
Thus, excess material is usually removed
Bulldozers and front-end loaders maneuver in and on the material which is
being removed. The bulldozer pushes the material by scraping. In a
stabilization/solidification operation, this movement of material may be to an
area where it is stabilized/solidified or to where it is loaded. Front-end
loaders are capable of removal and loading of solid material. This is an
advantage where the material must be placed in a dumptruck or a hopper for
transportation or processing.
Waste Transportation
Depending upon the nature of the waste and of the site, waste can be
transported by dump truck, pump and hose, or a fixed system such a conveyor
belt or screw auger system. Dump trucks are commonly used for solids
transportation, particularly when the liquid content is low and travel
distance is over a quarter-mile. An important consideration is that of
spillage, particularly since the waste may be hazardous. Truck beds should be
lined with plastic to prevent escape of waste when the waste contains liquid
or when the trucks will travel off site. In addition, the trucks should be
covered with tarpaulins. Such covering is essential when the material is of a
small particle size and subject to wind dispersion.
Conveyor transportation is used at a site where large amounts of waste are
to be moved over a fixed distance for long periods of time. Their setup is
complicated and costly, but this is offset by their ease of use once set up.
Conveyors are incapable of moving liquids and spillage is a problem unless the
material to be stabilized/solidified is dewatered or its water is decanted.
Since a conveyor is a piece of moving equipment, time must be allotted for
maintenance and repair. The use of sidewalls may be necessary to prevent
unwanted dispersal of hazardous materials.
Pumping of hazardous waste solids may be feasible when they are
sludge-like. In this instance the transportation function is also the removal
function. Pumping has the advantage that the waste can be directly sent to
the processing equipment.
Chemical Reagent Storage
Material stockpiling is an obvious requirement for the satisfactory
operation of a stabilization/solidification process. Primary requirements
are: (1) sufficient storage of agent so that operations are not delayed;
(2) ability to keep the agent dry, since virtually all stabilization/
solidification agents are dry; and, (3) ease of unloading upon delivery from
the supplier and to the process. Bins and hoppers are the primary storage
vessels for solid agents. These hoppers are sometimes transportable. Liquid
storage is occasionally required. Sometimes solid materials are delivered to
the site in bags, which are pal letted, or in bulk for storage in piles.
Typical chemical storage tanks are routinely used for this function.
7-3
-------
Mixing of tht hazardous wastf and Its stabilization/solidification apnt
1$ thi heart of the stabilization/solidification prงcซss, Most of thซ
stabilization/solidification activities that hivt occurred 1n thi United
Statts have wsid arta mixing. In area nixing, tht waste Is usually wither
riiซQvงeI nor transports! prior to the addition of a stabilization/
solidification agent. Instead, thi ttablltzatlon/solldlflcatloft tfltnt Is
delivered to thซ area to be stabilized/solidified and nixed with the waste
directly. Often, tracked backhots irt ustd for mixing* Typically, the water
has enough waste present for reaction with the ซtab111zer/sol1dlfler and the
waste. The waste Is nixed until the operator ptrctlvts that nixing Is
couplets. Thi benefits to this type of nixing ars; CD tht waste usually
need not be rtmoveci fron tht site; (2) the operation can proeatd with
traditional earth moving equipment; and (3) It Is Inexpensive. Offsetting
these benefits 1s the probable Incomplete and Intrfequitt nixing of thi waste.
A wide ranjt nixing equipment exists for usซ In Indostrlts which precis s
Typlcil nixing equlfment. syltublt for u$e 1ป stabilization/
solldlflcitfon operations, *re is follows: pws n111*i ribbon blenders,
nuelter n1xersป txtrudtrs, scrtir convtj'Ofs, Mtste ซnd rtagซnt can tot mettrid
into this equipment upon ml Ming is i nwans if quality control.
Sowฎ waste stabilization/ solidification contractors report thi yst of pug
wills for ซ1x1nf operations. Pug nills are namrfteturtd by stveril coiptnlis;
contractors occasionally modify thi pug nil! to 5ซ1t their special needs,
pills consist of douolt scrtus Into which ont material Is nlietf with another
on ซ flow-through basis* The materials are generally mixed prior to their
addition to the put ซm, but this Is only partial
Tht placenent of son-Hint materials can be performed In accordance with
procedyrts ysed 1n thง roidbulldlnf Industry, Here* the stabilized/solidified
waste Is placed 1n lifts of tight to tin 1nchซs using tarth-niovlng equipment
such ปi ffaders or bulltoiers* Follow! nง plactntnt, tht waste Is conpictid.
To tsswrt proper conpact1onป the optlnun nolsture cofttftftt of the wittrltl
needs to be determined. Tht optiroun nolstyrt content Is thtt moisture which
gives thi greatest density for i given wattrlal* Tht addition of moisture Is
fisctssary Eecaust toe little moisture dots not provide thi reqylrtd
lubrication for the son parti cits to s!1dป past one anothtr during
compaction. Too ranch moisture causts the material to approach tht density Of
water* which 1s prtsynibly lower than that of thi waste. Thus, for soil-like
stabilized/solidified hazardous wastt, the amount of water 1n tht waste nust
be controlled as the waste 1$ comp acted.
A stcond factor which affects tht coipictlon of tht wastt is the partlclt
size distribution of the material. Poorly graded wastes* which art
predominantly of out particle size only* So not compact well. Ntll-fradtd
Materials convict better s1ncซ the void volume of the larger particles Is
oceypltd by smaller particles living a better fit. This consideration 1s
wsua11y ont thst cinnot fat controlled unltss thi ptrtlcli slit dtstrlbutfon of
tht stabilization/ solidification agent can be regulated.
7.4
-------
REFERENCES
Caterpillar, Inc. 1987a. Caterpillar Performance Handbook, Edition 18.
Peoria, Illinois.
Caterpillar, Inc. 1987b. Caterpillar Performance Handbook: Hydraulic
Excavators. Peoria, Illinois.
Cullinane, M.J., Jr., L.W. Jones, and P.G. Malone. 1986 Handbook for
Stabilization/Solidification of Hazardous Wastes. EPA/540/2-86/001.
Hazardous Waste Engineering Research Laboratory, U.S. Environmental Protection
Agency, Cincinnati, Ohio.
Curry, M. 1986. Fixation/Solidification of Hazardous Waste at Chemical Waste
Management's Vicery, Ohio, Facility. In: Proceedings of Hazardous Materials
Control Research Institute Conference, December 1986. pp. 297-302.
Green, D.W., ed. 1984. "Processing Bulk Solids," in Perry's Chemical
Engineers Handbook, 6th ed. McGraw-Hill, New York. pp. 21-3-10.
Kyles, J.H., K.C. Malinowski, and T.F. Stanczyk. 1987.
Solidification/Stabilization of Hazardous Waste - A Comparison of Conventional
and No'vel Techniques, Toxic and Hazardous Wastes. In: Proceedings of the
19th Mid-Atlantic Industrial Waste Conference, June 21-23, 1987. Jeffrey C.
Evans, ed. pp.554-568.
National Lime Association. 1987. Lime Stabilization Construction Manual.
Bulletin 326. Arlington, VA.
National Research Council. 1987. Lime Stabilization-Reactions, Properties,
Design and Construction. Transportation Research Board, Washington, D.C.
Rowe, G., and API Waste Treatment Task Force. 1987. Evaluation of Treatment
Technologies for Listing Petroleum Refinery Wastes. Final Report, The
American Petroleum Institute.
Tittlebaum, M.E., et. al., 1985. "State of the Art on Stabilization of
Hazardous Organic Liquid Wastes and Sludges." CRC Critical Reviews in
Environmental Control, 15(2):191-193.
U.S. Environmental Protection Agency. 1986h. Mobile Treatment Technologies
for Superfund Wastes. Office of Solid Waste and Emergency Response.
EPA/540/2-86/003, September 1986.
7-5
-------
GENERAL PERSPECTIVES
Highly site-specific
Dependent on other
project phases
Expanded QA/QC program
PROJECT DEVELOPMENT
Site/waste Define problem(s)
characterization
Technology
screening
* Treatability
testing
Pilot testing/
design
Identify solution & formulate
implementation approach
Demonstrate technical feasibility
for a practical implementation
scheme
Develop/specify tailored
remedy
IMPLEMENTATION
BASIC IMPLEMENTATION FUNCTIONS
- Pretreatment
7-6
-------
GENERAL PREPARATIONS
Access
Site preparation - utilities
- grading for roads
- security
Health & safety - protective clothing
monitoring equipment
- dust control
- emergency medical
- communications
Decontamination - non-expendable equipment
- workers
- collection/treatment of rinseates
PRETREATMENT
Removal of large objects
Dewatering - water table suppression
- drainage beds
Neutralization - safety
- protection of equipment
- as part of treatment
Initial homogenization
WASTE REMOVAL
Operation in waste
- bulldozers scrape waste
- front-end loaders move and
load waste; they can be tracked
or use low pressure tires
Remote operation
- backhoes
- draglines
Consider equipment reach, cycle
time (make certain enough truck/
conveyor capacity is present
to haul waste)
7-7
-------
TRANSPORTATION
Pump & hose to remove liquids
Dump truck
- line & cover
- decontamination necessary
Conveyor belt
- not for liquids
- sidewalls necessary
Screw auger
UNTREATED WASTE STORAGE
Sloped to collect liquids
Lined to keep base clean
Rocks, twigs, etc. removed
to avoid liner puncture
Drainage pipes, sump & water
treatment system necessary to
handle liquids
Covered to prevent waste dispersion
Bermed to retard waste slumping
Rubber tire loader to move waste
CHEMICAL REAGENT STORAGE
Tank for liquids
Solids storage
- bins & hoppers
- palleted bags for lime & cement
- storage piles
Requirements
- keep solid reagents dry
- ease of unloading is important
- have sufficient quantity of
reagent on-hand to prevent
delays in operation
7-8
-------
WASTE/RE AGENT MIXING
Mobile plant
Area
In situ
In drum
MOBILE PLANT WASTE/RE AGENT MIXING
Pug mills, ribbon blenders.
mueller mixers
Process control (QC) is good
S/S waste replacement
- place in lifts of 6" to 8"
- compact considering optimum
moisture content & particle
size
AREA WASTE/REAGENT MIXING
Uses traditional earth moving equipment
Technique
- use LPTs or wide tracks
if in waste
- use timber matts to
support backhoes
Lime stabilization techniques
- soil preparation
- lime spreading
- soil/lime mixing
- compaction to achieve
practical density
- curing
7-9
-------
AREA WASTE/RE AGENT MIXING
(Continued)
Advantages
- inexpensive
- waste stays on site
(no transportation &
disposal costs)
However, mixing may be poor
IN-SITU MIXING PROCESSES
Used largely for pits, ponds,
lagoons, where liquids & sludges
are present
Vendors
- Geo-Con
- Enreco
- Harmon
- others
GEO-CON PROCESS
S/S agent delivered by auger &
caisson into waste
Mixing done by lifting & turning action
Depths to 100 ft. can be stabilized
Overlapping bore patterns allow for
complete coverage
* Advantages
- waste not excavated
- water table not lowered
- fugitive emissions controlled
- feed of agent can be metered
for good QC
7-10
-------
GEO-CON PROCESS
Continued
Cannot penetrate masses with boulders
or debris
Has other geotechnical applications
- dams
- slurry walls
SITE Program demonstration project
ENRECO IN-SITU PROCESSES
* S/S agent fed through
injector on backhoe
Mixing done by back & forth
action of delivery head
Depths to 100 ft can be stabilized
Volume increases of 10% can
be expected
HARMON
HSS system
- auger on front end of bulldozer
- good for 8" to 10" lifts
PF-5 injector
- 5 injection tubes have impellers
& augers to promote mixing
- these tubes are at the end of a
backhoe which reaches into the waste
- can be used to depths of 10 ft
7-11
-------
IN-DRUM WASTE/REAGENT MIXING
Use drum as mixing vessel &
waste container
Reagent will require additional
volume (more drums)
Important considerations
- how to access drum (bung
hole, top removal)
- safe operation?
Required equipment
- onsite chemical storage
- chemical batching system
- mixing system
- drum handling system
REPLACEMENT
Pumpable product
- fluid or "concrete like"
- time
- vibration to remove air voids
Compactable product
- cohesive or friable "soil-like"
- moisture conditioning for
maximum density
I I I I 1
I
I
I
I
8 m 1?. 14
16 Moisture content, %
Typical soil-cement moisture/density relationship.
7-12
-------
ACTIVATED
CARBON
TREATMENT EXHAUST
TANKS FAN
I
Crane-mounted mixing system advancing through
unstab1lized/unsol1d1f1ed sludge layer.
Source:. Geo-Con Inc., Pittsburgh, PA.
OTHER FACTORS
Segregation
Thickness
Exposed surface area
Cover
7-13
-------
COMPACTOR ZONES OF APPLICATION
100%
C1.AY
SILT
SHEEPSFOOT
100%
SAND
ROCK
GRID
VIBRATORY
SMOOTH STEEL DRUMS
' i "
MULTI-TIRED PNEUMATIC
I
HEAVY PNEUMATIC
I
VIBRATORY
TAMPING FOOT
TOWED TAMPING FOOT
HIGH SPEED TAMPING FOOT
CATERPILLAR
TAMPING FOOT
COMPACTIVE METHOD
Static Weight. Kneading
Static Weight, Kneading
Static Weight. Vibration
Static Weight
.Static Weight, Kneading
.Static Weight, Kneading
-Static Weight. Kneading
Static Weight, Kneading, Impact. Vibration
CATERPILLAR
TAMPING FOOT
Static Weight, Kneading. Impact, Vibration
Chart used to select equipment for compaction
of various-sized media.
Source: Caterpillar, Inc. Caterpillar Performance
Handbook, October 1987.
7-14
-------
QUALITY ASSURANCE PROCEDURES
FOR ENSURING
LONG-TERM PERFORMANCE
SECTION 8
Abstract 8-2
Slides 8-5
8-1
-------
IMPROVING QUALITY ASSURANCE/QUALITY CONTROL
FOR SOLIDIFICATION/STABILIZATION
Mr. Richard McCandless Mr. Peter Hannak
UC/Center H111 Lab CH2M Hill
Cincinnati, Ohio Waterloo, Ontario
Overview
Quality Assurance/Quality Control (QA/QC) is the backbone of all
solidification/stabilization (S/S) actions involving Superfund and RCRA
wastes. From waste characterization through bench testing, pilot testing
and implementation of the remedy, a through and well managed QA/QC program
is the only means by which confidence in the finished product can be
estimated.
Quality Assurance is defined as all activities designed to ensure that a
specified product performance will be achieved with a stated level of
confidence. Quality Control is a part of QA and involves all activities
intended to control the quality of a product so that It does meet the
specified criteria. Whereas QA relates to planning and overall verification
(what and how), a QC program involves checks on the measurement systems to
demonstrate that they are in calibration and being applied properly at the
right time and place. A simplification of the concept might be stated as:
"QA IS DOING THE RIGHT THING; QC IS DOING THINGS RIGHT."
Treatments of this subject often tend to focus on QA/QC objectives
(accuracy, precision, etc.) and can be less than enlightening since
statements describing the level of numerical control anticipated or desired
do not help to answer the questions "What should I measure and how?" "How
good is good enough and how will I know when I've succeeded?" The usual
answer to the latter question is "good statistics", but good judgement and
common sense are at least as important. Cookbook methods do not exist and
cannot be offered here. What can be offered are suggestions based on
limited experience that may help to minimize oversight, avoid latent
pitfalls and in general improve our ability to generate reliable Information.
A sound engineering strategy and a good understanding of the relationship
between project phases is key to making appropriate decisions along the
way. Each phase of the project builds upon the observations and findings of
the proceeding phase; for better or worse. For practical reasons, however,
this dlcussion focuses on specific problem areas in specific phases of a
typical project. For example, although the topic of mixing 1s relevant in
several phases, it is discussed in connection with pilot testing since this
phase represents the "bridge" between idealized bench testing and the real
conditions to be encountered 1n implementation. A general outline of this
session follows:
8-2
-------
Characterization and Sampling Practice for Known and Unknown
Conditions
Bench Testing
Physical Sample Size and "Representativeness"
Chemical Baseline Needs
Significant Variability 1n Analytical Data and other Factors
affecting Test Results
Pilot Testing
Mixing Practice, Parameters and Performance
Implementation
Process Control Requirements and suggested methods for Monitoring
Uniformity
Prescriptive versus Performance Contracts and Impacts on QA/QC
REFERENCES
AICHE Equipment Testing Procedure, Drv Sol Ids. Paste and Dough Mixing
Equipment: Second Edition, American Institute of Chemical Engineers, New
York, N.Y., 1979,
Barth, E,F,ป and McCandless, R.M., et.al., General Guide for TreatablHtv
Assessment: Draft S/S Technology Information Bulletin for the USEPA
Engineering Forum. USEPA Risk Reduction Engineering Laboratory. Cincinnati,
Ohio, July, 1989.
CheMcal Quality Management - Toxic and Hazardous Hastes: U.S. Army COE
Engineer Regulation 1110-1-263, December 30, 1985.
Contract-Construction Quality Management: US Army Corps of Engineers, ER
1180-1-6, July 31, 1986,
Handbook for Stabilization/Solidification of Hazardous Hastes.;
EPA/540/2-86/001, June 1986.
HorwUz, W., Kaips, UR. and Boyer, K.H., Quality Assurance 1n the Analysts
of Foods for Trace Constituents: Journal of the Association of Official
Analytical Cheroists, Inc., Vol. 63, No. 6, 1980.
Keller, D.3., Construction Quality Assurance for Stabilization/
5o.]^if teat ion: Draft Final Report, W.A.# 2-17. USEPA Risk Reduction
Engineering Laboratory, Cincinnati, Ohio, August 31, 1989.
8-3
-------
Perry. R.H., Chemical Engineers' Handbook: McGraw-Hill Book Co., New York,
N.Y., 1984.
Quality Control In Remedial Site InvestigationHazardous and Industrial
Solid Haste Testing: C. L. Perket, Editor. ASTM STP 925, Fifth Volume,
1986. ASTM Publication Number (PCN) 04-925000-16.
Soil Sampling Quality Assurance User's Guide: Second Edition,
EPA/600/8-89/046, March, 1989.
Taylor, John Keenan, Quality Assurance of Chemical Measurements: Lewis
Publishers, Inc., Chelsea, Michigan, 1987.
8-4
-------
OBJECTIVES
OA: DOING THE RIGHT THMG
(what)
DOING THINGS RIGHT
(how)
8-5
-------
BENCH
SITE
IMPLEMENT
CONTROL OF
PRODUCTION
TOPICS for REVIEW
BENCH
SITE
IMPLEMENT
CHARACTERIZATION
SAMPUNQ PRACTICE
PROCESS
CONTROL
SIGNIFICANT
VARIABILITY
TOPICS for REVIEW
BENCH
SITE
IMPLEMENT
CHARACTERIZATION
SAMPLING PRACTICE
J-6
-------
CHARACTERIZATION AND
SAMPLING PRACTICE
Critical Information
Waste types
Conditions
Distribution
Quantities
CHARACTERIZATION AND
SAMPLING PRACTICE
Sampling Design
"ASTM Standard Guide for
General Planning of Waste
Sampling" (in development)
Not for unknown or abandoned
sites or wastes
CHARACTERIZATION AND
SAMPLING PRACTICE
SampGng Schemes
Judgement deciding through visual
observation or knowledge of the site
Systematic: statistical basis for entire
waste body only where known to be
homogeneous; otherwise by waste stratigraphy
* "n" can be calculated based on estimate
of variance of NORMAL population
UBefors "goodness of fit" test for
nonrtatty of population generally required
8-7
-------
CHARACTERIZATION AND
SAMPLING PRACTICE
Product
-Credible "worst case" composite
for bench testing
Level of effort
EXPENDITURES FOR INFORMATION
$
TOPICS for REVIEW
BENCH
SITE
IMPLEMENT
8-8
-------
SAMPLE SIZE
Representative physical sizenot "n"
Some guidance for physical tests (ASTM)
- concrete specimens for strength:
minimum dimension of sample = 3 times
maximum dimension of largest particle
- grain size distrbution of sols:
mass of sample for test "proportional"
to nominal diameter of largest particle
SAMPLE
(continued)
Some guidance for physical tests (ASTM)
- recognize limitations of test equipment
No quidance for chemical tests
- acid digestion for metals bitted
to a few grams
- need to test "leach test size" samples
FRACnONATION/ACID DIGESTION
FOR HEAVY METALS
(TAD"; under development)
Combines gravimetric separation
(ASTM D4371) with cold acid
extraction (MSA 19-3.4)
Untreated waste or treated waste
before "set"
Measure amount soluble in strong
add; not "totar
8-9
-------
FRACTIONAT10N/ACID DIGESTION
FOR HEAVY METALS
("FAD"; under development)
(continued)
Test entire "leach test size" specimen
- 1 L 20% nitric acid for
100g waste (S.G.= 1.1)
- agitate 7 hours, separate (settle)
- filter and weigh "floaters"
and "sinkers"
- analyze extraction liquid
CHEMICAL BASELINE
What?
Waste
Why?
Safety check
Verification of "worst case"
Interference
Binder Unexpected leach test results
Hazardous?
* Waste & Homogeneity a bad assumption
binder mix Measure actual variability for
-Calculations of confidence
intervals
-performance comparisons
How?
SIGNIFICANT VARIABILITY
* How much variability should
I expect in measuring the
concentrations of analytes?
How can I estimate variability
in order to calculate "n"?
Review
CV: The variability expressed as a
percentage of the mean
8-10
-------
60
30
20
o
.0 10
S/S EXPERIENCE
D Metals In Soil Wastes
A Metals In Leachates
10-'
10-3
10-'=
10-"
E
a.
a.
Concentration
of vacation xj * function of concentration.
HORWITZ ET AL: A ASftOC. OFF. AMAL. CHCM. CVOL. ซS. HO. e. 1MO)
SOURCES OF SIGNIFICANT
VARIABILITY
Sample Handling
Mixtig
Molding
doing
Storage
Shipping
UNCONFINED COMPRESSIVE STRENGTH
Low temp Low temp Low tan
8-11
-------
OBSERVED VARIABILITY
RepGcates for Physical Testing
Test ft Products No. of
Method Tested Median Replicates Precision
Bulk
Density 69 1^44 3 +/- 0.14
(g/cc)
Specific
Gtavtty
Wet
Method 69
Dry
Method
55
2.48
2.34
+/- 0.28
+ /- 0.20
OBSERVED VARIABILITY
Replicates for Physical Testing
(Continued)
Test tt Products No. of
Method Tested Median Replicates Precision
Moisture
Content
(%,w/ww)
69
253
HydrauEc
Conductivity 37 3x10 'a
(m/s)
UCS
(kPa)
66
1760
4
4
+/- 1.6
630%
56%
TOPICS for REVIEW
BENCH
SITE
5-12
-------
MIXING
Objective
- Intimate association of
waste and binder
Practice - a materials science
of three domains
- Uqtdd-Bquld
- Solid-solid
- Liquid-solid
Bench-Scale Approach
Smafl quantities
Closest approach to ideal mixmg
May not be practical or
representative of plot scale
Pilot-Scale Approach
Large quantities
Practical optimization to
real conditions
8-13
-------
MIXING
Approach to Scale-up
Power requirement proportional to
unit process volume so long as
equipment geometry unchanged
Mixing time requirement inversely
proportional to mixing speed
IMPORTANT MIXING PARAMETERS
Waste and Binder
Particle size distribution
Bide density
* True density
Particle shape
Surface area and charge
characteristics
IMPORTANT MIXING PARAMETERS
Waste and bolder
(continued)
Row characteristics
Friability
State of agglomeration
Moisture content
Density, viscosity and surface
tension of liquids added
8-14
-------
IMPORTANT MIXING PARAMETERS
Equipment
Mechanism design - blades, baffles, cams,
impellers, refers, rods, bate,
screw augers, extruders
htensfty
* Duration/retention time - proper
combination of mechanism design and
intensity should produce desired blend
in a few minutes; 15 minutes maximum
IMPORTANT MIXING PARAMETERS
Performance
(Axing trials and evaluation required
Refer to AJChE procedures for
conducting and interpreting performance
tests on mixing equipment
"Dry Solids, Paste and Dough Mxkig Equipment
Testing Procedure", American Institute of Chemical
Engineers, Second Edition, New York, 1979
TOPICS for REVIEW
IMPLEMENT
CHAHACTEraZATKHI
SAMPLING PRACTICE
8-15
-------
PROCESS CONTROL
Excavation and pre-processing
Mixing - quantities, time, energy
Ratio control
Documentation
Experience
"SLOW" QC TOOLS
PHYSICAL
Unconflned Compresslve Strength
Cone Penetrometer
Cement Content of Freshly Mixed
Soil-Cement (ASTM D-2901)
CHEMICAL
Add Neutralization Capacity
Fract1onat1on/Add Digestion
Inert Spikes
LEACHING
TCLP
EP Toxldty
FOR VERIFICATION ON-SITE
HASTE PRODUCT
IN OlIT
X
X
X
X
X
X
X
X
X
X
X
X
X
TIME
FACTOR
D
D
H
D
D
D
D.H
D.W
"QUICK" QC TOOLS FOR
PHYSICAL INDICATORS
Color - Visual
Texture Visual
Hater Content
Grain Size
1 Fines (-200 Sieve Size)
Unit Weight
Viscosity - Slump
Shear
Temperature
Optical Tracers - Dyes
- Mlcrotaggants
CHEMICAL INDICATORS
l_pH
X-Ray Fluorescence
MONITORING PROCESS UNIFORMITY
HASTE PRODUCT TIME
IN OUT FACTOR
X
X
X
X
X
X
(X)
(X)
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
M
M
M.H
H
M
M
M
M
M
H
H
M
M
8-16
-------
CONTRACT OPTIONS
or '^methods" contract
- tow contractor risk; tow .price
Performance or "results" contact
- tow government risk so long
as criteria dearly defined
- higher contractor risk and cost
may be offset by latitude
for innovation
SUMMARY
Construction Contract Quafity
Management Checklist
Waste chafacterization
- Quantity
- CondHjosi & distribution
- toterferanits
Treatment objectives
- Target analytes
- Treatment tevete
- Sampfing & testing procedures
- Required physical properties
- Volume increase restrictions
SUMMARY
'Construction Contract Quality
Management Cbeckist
* Process Requrements
- Qnanffies
- Proportions
- Pre-lreatoe
Pranoaig needs for processes
sensjifve to waste variaMRy
- Required physical and chemteai performance
-MeUiods used to assess performance
8-17
-------
SUMMARY
Construction Contract Quality
Management Checklist
Testing requirements
- Methods for waste & binder
characterization
- Calibration of weight & volume
measuring equipment
- Mixing performance
- Quick and simple "on-One"
production tests
SUMMARY
Construction Contract Quality
Management CheckGst
Post-placement tests
- Strength, teachability
- bi situ or sampled
- Frequency
- Duration
- Chain-of-custody
SUMMARY
Construction Contract Quality
Management Checklist
Contractor QC plan I
- Qualifications of technical and
supervisory personnel
- Outline of construction process
with details on S/S methods,
equipment & schedule
- QC sampling & testing methods to be used
- Action to be taken if criteria are not met
- Health and safety
8-18
-------
SUMMARY
Construction Contract QuaEty
Management Checklist
I* Government QA plan I
- Identify those responsible for:
- Review/approval of contractor QC plan
- Conduct pre- construction and periodic
meetings for QM review
- Evaluation of construction inspections
and review of submittals
- Perform:
- Job site sampling & testing
- Inspection of corrective actions
SUMMARY
Invest resources to define the
problem(s) as wefl as practical
Establish objectives that are
sensfote and achievable
Do not assume - measure
Treat and test with implementation scheme h mind
Calibrate indirect measurement systems used hi QC
Maintain a dear division of responstofities
in the field and document.
'If h?s not written down, ft dkirrt happen"
8-19
------- |