SEPA
United States
Environmental Protection
Agency
Industrial Environmental Research
Laboratory
Research Triangle Park NC 27711
EPA-600/7-80-118
May 1980
Comparison of Four
Leachate-generation
Procedures for Solid
Waste Characterization
in Environmental
Assessment Programs
Interagency
Energy/Environment
R&D Program Report
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RESEARCH REPORTING SERIES
Research reports of the Office of Research and Development, U.S. Environmental
Protection Agency, have been grouped into nine series. These nine broad cate-
gories were established to facilitate further development and application of en-
vironmental technology. Elimination of traditional grouping was consciously
planned to foster technology transfer and a maximum interface in related fields.
The nine series are:
1. Environmental Health Effects Research
2. Environmental Protection Technology
3. Ecological Research
4. Environmental Monitoring
5. Socioeconomic Environmental Studies
6. Scientific and Technical Assessment Reports (STAR)
7. Interagency Energy-Environment Research and Development
8. "Special" Reports
9. Miscellaneous Reports
This report has been assigned to the INTERAGENCY ENERGY-ENVIRONMENT
RESEARCH AND DEVELOPMENT series. Reports in this series result from the
effort funded under the 17-agency Federal Energy/Environment Research and
Development Program. These studies relate to EPA's mission to protect the public
health and welfare from adverse effects of pollutants associated with energy sys-
tems. The goal of the Program is to assure the rapid development of domestic
energy supplies in an environmentally-compatible manner by providing the nec-
essary environmental data and control technology. Investigations include analy-
ses of the transport of energy-related pollutants and their health and ecological
effects; assessments of, and development of, control technologies for energy
systems; and integrated assessments of a wide range of energy-related environ-
mental issues.
EPA REVIEW NOTICE
This report has been reviewed by the participating Federal Agencies, and approved
for publication. Approval does not signify that the contents necessarily reflect
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commercial products constitute endorsement or recommendation for use.
This document is available to the public through the National Technical Informa-
tion Service, Springfield, Virginia 22161.
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EPA-600/7-80-118
May 1980
Comparison of Four Leachate-
generation Procedures for Solid Waste
Characterization in Environmental
Assessment Programs
by
Daniel E. Bause and Kenneth T. McGregor
GCA/Technology Division
213 Burlington Road
Bedford, Massachusetts 01730
Contract No. 68-02-3129
Task No. 103
Program Element No. 1AB604
EPA Project Officer: Frank E. Briden
Industrial Environmental Research Laboratory
Office of Environmental Engineering and Technology
Research Triangle Park, NC 27711
Prepared for
U.S. ENVIRONMENTAL PROTECTION AGENCY
Office of Research and Development
Washington, DC 20460
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DISCLAIMER
This Final Report was furnished to the Environmental Protection Agency
by GCA Corporation, GCA/Technology Division, Burlington Road, Bedford,
Massachusetts Ul/30, in fulfillment of Contract No. 68-02-3129, Technical
Directive 103. The opinions, findings, and conclusions expressed are those
of the authors and not necessarily those of the Environmental Protection
Agency. Mention of company or product name is not to be considered as an
endorsement by the Environmental Protection Agency.
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ABSTRACT
Four leachate procedures were evaluated in terms of their general appli-
cability, reproducibility, Environmental Assessment methods compatibility, and
leaching characteristics. The leachates generated by these methods were ana-
lyzed for nine metals by atomic absorption methods and by ion chromatography
for F"~, Cl", and SOi,2". Seven energy process wastes including oil shale, FBC
waste, fly ash, boiler slag, scrubber sludge, and hopper ash were extracted to
evaluate the general applicability of the leachate tests. The ASTM methods
had the best reproducibility and the EP method had the poorest. The EP and
CAE procedures leached the largest quantities of trace metals from the wastes.
However, based on the total metal concentration in the sample, the leachate
methods generally extracted < 1 percent. The EP and ASTM-B methods caused
some problems with flameless AA analyses. Based on the RCRA criteria, five
of the energy wastes would be classified as hazardous by at least one of "the
leachate procedures. Selenium usually exceeded the threshold value for the
leachate.
In view of the results obtained in this study, the ASTM-A and CAE are
the preferred leachate generation procedures. Regardless of the leachate
method selected for waste characterization, the experimental procedure must
be defined more precisely with respect to the separation of phases in complex
industrial wastes, the preparation of the sample for leaching, the agitation
apparatus and rate, and the preservation of the leachate for the subsequent
analyses.
iii
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CONTENTS
Abstract
Figures vi
Tables vi
Acknowledgment xi
1. Introduction 1
2. Summary and Conclusions 3
3. Recommendations 6
4. Overview of Leachate Problem 8
Background 8
Objectives 9
General Considerations for Leachate Generation 13
Factors Affecting Concentration in Leachates 14
5. Literature Review 18
Previous Reports 18
6. Experimental 38
EPA-OSW Extraction Procedure 38
ASTM-A Method (Water Extraction) 40
ASTM-B Method (Acetate Buffer Extraction) 41
Carbonic Acid Extraction 42
Atomic Absorption 42
Ion Chromatography 43
Spark Source Mass Spectrography ..... 43
7. Results and Discussion 45
General Applicability of the Leachate Methods 45
Leaching Characteristics 50
Precision of Leachate Methods 62
Variations in Leachate Procedures 72
Compatibility with Environmental Assessment Procedures. . 73
References 76
Appendices
A. Tables of Leachate Concentrations of Inorganic
Contaminants 78
B. Spark Source Mass Spectrography Data for the EP Leachate of
Bituminous Coal Fly Ash No. 1 and the EP Leachate Blank . . 91
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FIGURES
Number Page
1 EP extractor 39
TABLES
Number Page
1 List of Toxic Substances 9
2 Comparison of Experimental Parameters for the ASTM-A,
ASTM-B, EP, and CAE Leachate Methods 11
3 Chemical Composition of University of Wisconsin's Synthetic
Municipal Landfill Leachate 20
4 Comparison of Three Leaching Tests 20
5 The Number of Times Acid or H20 Leaching Solutions Gave
Highest Concentrations or Release of an Inorganic
Parameter From a Waste 22
6 Standard Deviation Calculations for Multiple Replicates of
Paint Waste Leached With Synthetic Leachate Using
SLT Procedures 23
7 Comparison of Metals Analyses for Sewage Sludge EP Extract . . 27
8 Trace Elemental Analyses of As-Contaminated Groundwater
Sample, EP Extracts, and Blank 28
9 Hazardous Potential Summary 30
10 ICAPS Screening Analysis of EP Extracts: Approximate Elemental
Composition of Extracts From Selected Waste Samples .... 32
11 Average Relative Standard Deviation for AAS Analyses of
EP Extracts 33
vi
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TABLES (continued)
Number Page
12 Evaluation of Extraction Procedure (EP): Average Means and
Standard Deviations for AAS Analyses of EP Extracts of
Wastes From Ponds 0 and P, Site A 33
13 Quality Control Data: Comparison of Barium Spike Recovery
From Selected Samples (Matrices) 34
14 EP Reproducibility 36
15 Description and Analysis of Waste Samples 46
16 Summary of Final pH for Wastes Tested 50
17 Detection Limits for Atomic Absorption and Ion Chromatographic
Analyses 52
18 Wastes Classified as Toxic by RCRA Criteria 53
19 Comparison of Leachate Data (In ug/g) for Oil Shale 54
20 Comparison of Leachate Data (In ug/g) for FBC Waste 55
21 Comparison of Leachate Data (In ug/g) for Bituminous
Coal Fly Ash No. 1 55
22 Comparison of Leachate Data (In ug/g) for Bituminous
Coal Boiler Slag 56
23 Comparison of Leachate Data (In ug/g) for Lignitic Coal
Scrubber Sludge 56
24 Comparison of Leachate Data (In ug/g) Generated by the
ASTM-A Procedure for Hopper Ash 57
25 Comparison of Leachate Data (In ug/g) Generated by the
ASTM-B Procedure for Hopper Ash 57
26 Comparison of Leachate Data (In ug/g) Generated by the
Extraction Procedure for Hopper Ash 58
27 Comparison of Leachate Data (In ug/g) Generated by the
Carbonic Acid Extraction for Hopper Ash 58
28 Number of Times Each Leachate Test Gave the Highest Concen-
trations of an Inorganic Contaminant 60
vii
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TABLES (continued)
Number
29 Number of Times Each Leachate Test Gave the Largest Quantity
(Mass/g of Sample) of an Inorganic Contaminant 60
30 Percentage Leached From the FBC Waste 63
31 Percentage Leached From the Bituminous Coal
Fly Ash No. 1 63
32 Percentage Leached From the Bituminous Coal
Fly Ash No. 2 64
33 Percentage Leached From the Bituminous Coal
Boiler Slag 64
34 Percentage Leached From the Lignite Scrubber Sludge 65
35 Percentage Leached From the Hopper Ash 65
36 Calculation of Relative Standard Error From Results of Hopper
Ash Extractions 67
37 Calculation of Relative Standard Error (RSE) for Each
Leachate Generated by the ASTM-A Method 68
38 Calculation of Relative Standard Error (RSE) for Each
Leachate Generated by the ASTM-B Method 69
39 Calculation of Relative Standard Error (RSE) for Each
Leachate Generated by the EP 70
40 Calculation of Relative Standard Error (RSE) for Each
Leachate Generated by the CAE Method 71
41 Comparison of Analytical Data (In ug/g) Generated by Varia-
tions of ASTM-A Procedure For Oil Shale 73
42 Comparison of Leachate Data (In yg/g) for Bituminous Coal
Fly Ash No. 2 74
A-l Concentrations of Inorganic Species in Oil Shale Leachate
Generated by the ASTM-A Method .......... 78
A-2 Concentrations of Inorganic Species in Oil Shale Leachate
Generated by Variations of the ASTM-A Method 79
A-3 Concentrations of Inorganic Species in Oil Shale Leachate
Generated by the ASTM-B Method 79
vlii
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TABLES (continued)
Number
A-4
A-5
A-6
A-7
A-8
A- 9
A- 10
A-ll
A-12
A-13
A- 14
A-15
A- 16
A- 17
A- 18
Concentrations of Inorganic Species in Oil Shale Leachate
Concentrations of Inorganic Species in Oil Shale Leachate
Generated by the CAE
Concentrations of Inorganic Species in FBC Waste Leachate
Generated by the ASTM-A Method
Concentrations of Inorganic Species in FBC Waste Leachate
Generated by the ASTM-B Method
Concentrations of Inorganic Species in FBC Waste Leachate
Generated by the EP
Concentrations of Inorganic Species in FBC Waste Leachate
Generated by the CAE
Concentrations of Inorganic Species in Bituminous Coal
Fly Ash No. 1 Leachate Generated by the ASTM-A Method . , .
Concentrations of Inorganic Species in Bituminous Coal
Fly Ash No. 1 Leachate Generated by the ASTM-B Method . . .
Concentrations of Inorganic Species in Bituminous Coal
Concentrations of Inorganic Species in Bituminous Coal
Fly Ash No. 2 Leachate Generated by the ASTM-B Method . . .
Concentrations of Inorganic Species in Bituminous Coal
Concentrations of Inorganic Species in Boiler Slag Leachate
Generated by the ASTM-A Method
Concentrations of Inorganic Species in Boiler Slag Leachate
Generated by the ASTM-B Method
Concentrations of Inorganic Species in Boiler Slag Leachate
Concentrations of Inorganic Species in Scrubber Sludge
Leachate Generated by the ASTM-A Method
80
80
81
81
82
82
83
83
84
85
86
86
87
87
87
ix
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TABLES (continued)
Number Page
A-19 Concentrations of Inorganic Species in Scrubber Sludge
Leachate Generated by the ASTM-B Method 88
A-20 Concentrations of Inorganic Species in Scrubber Sludge
Leachate Generated by the EP 88
A-21 Concentrations of Inorganic Species in Scrubber Sludge
Leachate Generated by the CAE 88
A-22 Concentrations of Inorganic Species in Hopper Ash Leachate
Generated by the ASTM-A Method 89
A-23 Concentrations of Inorganic Species in Hopper Ash Leachate
Generated by the ASTM-B Method 89
A-24 Concentrations of Inorganic Species in Hopper Ash Leachate
Generated by the EP 90
A-25 Concentrations of Inorganic Species in Hopper Ash Leachate
Generated by the CAE 90
B-l SSMS Data for the EP Leachate of Bituminous Coal
Fly Ash No. 1 92
B-2 SSMS Data for the EP Leachate Blank 93
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ACKNOWLEDGMENT
The authors gratefully acknowledge the guidance and support provided by
the Project Officer, Mr. Frank Briden. We thank Dr. James Epler, Dr. Wayne
Griest, and Dr. C.W. Francis and their co-workers at Oak Ridge National
Laboratory for sharing the results obtained from their leachate investigations.
The authors acknowledge the support of Dr. Kenneth Duke and his co-workers at
Battelle Laboratories in Columbus, Ohio for their insight into the application
of the bloassaya to the leachates. The authors appreciate the cooperation
provided by Ms. Cheryl Palesh at Engineering-Science, McLean, Virginia in
conjunction with the ASTM round-robin program. The authors also acknowledge
the following GCA/Technology Division staff members: Mr. Richard Dionne,
Ms. Patrice Svetaka, Mr. Virgilio Gonzales, Ms. Mary Kozik, and Ms. Sandra
Sandberg for conducting the laboratory analyses, and Ms. Susan Spinney and
Ma. Jacqueline McCarthy for typing the manuscript.
xi
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SECTION 1
INTRODUCTION
The disposal of industrial wastes has become an important environmental
issue. The hazardous species which could be leached from the wastes of the
disposal is the primary source of concern. The magnitude of the industrial
waste problem seems overwhelming. While estimates vary with their source and
with the industrial categories considered, estimates of about 400 million tons
have been given for annual production. Of particular interest to this study
are energy processes. Electric utilities, for example, are major generators,
with scrubber sludge being a growing problem. It is expected that over 30
million dry tons of scrubber sludge will be generated annually by 1985.
In order to assess the potential deleterious environmental effects that
individual wastes could produce after disposal, a means of characterizing the
leaching properties of waste materials is required. Characterization of the
leachate from a waste material, in terms of elemental concentrations or other
parameters that represent potential toxicity, is a relatively straightforward
analytical exercise; however, development of a laboratory test to predict the
leaching characteristics of a waste after disposal is the crux of the problem.
Indeed, development of a laboratory test that attempts to accurately predict,
in the general case, the fate of wastes after disposal is not a technically
nor economically feasible endeavor. Individual disposal environments vary
widely, and the quantities of waste requiring characterization are sufficiently
large that assessment of a waste material and its disposal options using
laboratory tests devised on a case-by-case basis is precluded.
The approach taken to characterizing leaching properties must then be
constrained to a standard test or series of tests which can be cost effectively
applied to the majority of wastes and yield information comprising a comparable
set of leaching characteristics. Such data can then be used to rank the poten-
tial hazards of the waste and provide insights into the disposal requirements.
Several leachate generation methods have been suggested for the deter-
mination of the environmental impact of a landfill waste. Four generation
methods were evaluated in this study. The methods studied include the
Environmental Protection Agency, Office of Solid Waste (EPA-OSW) proposed
procedure, the two procedures proposed by the American Society for Testing
and Materials, and a procedure employing a carbon dioxide-saturated water
leaching medium as an alternative to other acidic media. These evaluations
were aimed at determining a single method that would be most suitable for
Environmental Assessment (EA) needs.
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Because the EA programs presently being conducted are principally con-
cerned with energy systems, the leachate generation procedures investigated
under this study were applied to a variety of energy process wastes. An
effort was made to analyze a cross-section of these waste materials in order
to determine the general applicability of the methods. Both conventional
wastes and advanced process wastes were employed in the evaluations.
Also as part of this study, efforts were made to assemble and summarize
the existing data on leachate procedures and to assess concurrent leachate
generation studies being conducted by various organizations. These findings
are presented in Sections 4 and 5 which provide an overview of the leachate
generation problem and previous reports, respectively. These data are dis-
cussed in conjunction with the data resulting from this study in Section 7.
All analytical data collected are tabulated in the Appendices.
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SECTION 2
SUMMARY AND CONCLUSIONS
In an effort to fulfill the solid waste characterization needs of Environ-
mental Assessment (EA) programs, four leachate generation methods have been
evaluated. The evaluations include the following methods:
EPA-OSW Extraction Procedure (EP) an open system, acetic
acid extraction.
ASTM Method A a closed system, water extraction.
ASTM Method B - a closed system, acetic acid-acetate
buffer extraction.
Carbonic Acid Extraction (CAE) a closed system C02-saturated
water extraction.
The principal criteria used to evaluate these leachate methods were:
« General Applicability Any procedure employed as part of
EA methodology must be amenable to a wide range of waste
materials.
Reproducibility In order to make valid judgments regarding
the potential hazard of a waste, the reproducibility of the
generation procedure must be well defined.
e EA Methods Compatibility It is highly desirable that
the leachate produced not necessitate modifications to
the EA established analytical procedures.
Leaching Characteristics To the extent practical in the labo-
ratory, the leachate generation procedure utilized should simu-
late the anticipated fate of the waste.
To evaluate the general applicability, the four leachate methods were
applied to seven energy process wastes, including oil shale, FBC waste, fly
ash, boiler slag, scrubber sludge, and hopper ash. For the wastes tested, no
procedural problems were encountered with any of the leaching methods.
The final pH of the leachates generated by the ASTM-A method correlates
with the predominance of iron or calcium oxide in the waste. The amorphous
iron oxides produce an acidic solution, while the lime (Ca(OH)2) yields a basic
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extract. The basicity of the FBC waste and hopper ash offset the acidic media
of the ASTM-B, EP, and CAE leachates and produced a final basic pH.
Except for mercury, the metals cited in the RCRA regulation (Ag, As, Ba,
Cd, Cr, Pb, and Se) were analyzed by graphite furnace atomic absorption spec-
troscopy (AAS). Mercury was determined by the cold vapor method. In addition
to these analyses, calcium was determined by flame AAS and the anions, fluoride,
chloride, and sulfate, were quantitated by ion chromatography (1C). Graphite
furnace techniques were used because the trace metal concentrations in most of
the leachates were below the detection limits for flame AAS.
When the leachate concentrations are compared for the wastes extracted by
all four leachate procedures, the ASTM methods produced the highest concentra-
tions for most of the inorganic contaminants. The high leachate concentration
is a reflection of the large sample quantity used for the ASTM methods (350 g)
and the low liquid-to-solid ratio (4:1). The quantity of metal (or anion)
leached per gram of dry solid is generally higher, however, for the EP and CAE
methods. The EP, in particular, leached the largest quantities of inorganic
species, which is probably an indication of its rigorous agitation method.
The stainless steel extractor may also be breaking up the waste material,
exposing new surfaces to the leachate, and yielding high leachate quantities
which are an artifact of the shaking apparatus.
Based on the results of the extractions, it appears that some leachate
procedures exhibit an elemental selectivity. More cadmium (in pg/g of dry
sample) is extracted by the ASTM-B method than by the other leachate methods.
The CAE leaches more of the selenium, arsenic, and silver, and the EP effectively
solubilizes most of the trace elements and especially the major components,
culcium and sulfate. The extraction of cadmium by the ASTM-B method seems to
be correlated with the pH of the leachate. Except for the hopper ash, the
cadmium was extracted in the largest quantity by the precedure having the low-
est final pH. In most cases, this was the ASTM-B method.
Five of the energy wastes produced leachates which would be classified as
hazardous by the RCRA criteria. The toxic leachates were extracts of oil shale,
bituminous coal fly ash, scrubber sludge, and hopper ash. Hazardous leachates
for the scrubber sludge and hopper ash were produced by all four methods. As
indicated previously, the ASTM methods produced the highest metal concentration
in the leachates, and consequently, they yielded the largest number of toxic
leachates.
In most cases, the concentration of selenium exceeded the threshold level
regardless of the method used for extraction. The availability of selenium on
the surface of the samples and its solubility in acidic, neutral, and basic
solutions account for its ease of extraction. The anionic character of sele-
nium, probably as SeG^2", could account for its solubility in solutions of
widely varying pH.
Arsenic and chromium have also been shown to concentrate on the surface
of fly ash particles and both are soluble in acidic media. Unlike selenium,
however, they are sparingly soluble in H20. When arsenic and chromium ex-
ceeded the RCRA threshold values, it was only in the fly ash and hopper ash
wastes and only for the leaching tests which used acidic solutions.
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Percentages of the metals extracted from the wastes were based upon the
Inductively Coupled Argon Plasma Spectroscopy (ICAPS) or AAS analysis of the
total metal concentration in the waste. In general, the results indicate
that less than 1 percent of the metal was leached from the wastes.
The precision of the leachate methods was determined by calculating the
relative standard error (RSE) for replicate extractions of a solid waste.
The ASTM methods had similar reproducibilities with the ASTM-A method ranked
first. The CAE ranked third but was close to the reproducibility of the
ASTM methods. The EP consistently had the poorest precision of the four
leachate tests.
The compatibilities of the leachate procedures with standard EA methodo-
logies were also evaluated in this study. The presence of the acetate ion
interfered with the 1C determination for fluoride and chloride. The large
excesses of acetate masked the fluoride and chloride peaks and made quantita-
tion of these anions impossible under standard operating conditions. Elimina-
tion of this interference may be possible by operating parameter modification;
however, further studies would be required to address the feasibility of
such resolution. Although no bioassay tests were run on the leachates genera-
ted under this program, the inherent toxicity of the EP leaching medium has
been documented.1 Since problems associated with the bioassays are apparently
caused by the presence of acetate in the leachate, the ASTM-B method should
also show the same effects. The leachates generated by the CAE must be sub-
jected to the health and ecological tests to determine the compatibility of
the CAE with these bioassays. The leaching media of the EP and ASTM-B methods
also caused rapid deterioration of the graphite tubes during the AAS analyses.
This required frequent monitoring of the condition of the graphite tubes by
injection of standard solutions, resulting in decreased sample throughput and
increased analytical expense.
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SECTION 3
RECOMMENDATIONS
Of the four leachate procedures evaluated, the ASTM-A and Carbonic Acid
Extraction would be preferred for a standard leachate test. In terms of leach-
ing characteristics, the CAE extracts a greater quantity of inorganic contami-
nants than ASTM Method A. However, the reproducibility of ASTM-A is somewhat
better than the CAE. No analytical problems were encountered with either method
and both procedures could adequately handle the wastes tested in this program.
The leachates from the CAE would have to be subjected to the bioassay tests to
determine the compatibility of the CAE with the health and ecological tests.
The major criticism of all proposed procedures is the lack of sufficient
detail. A standard leachate procedure must be explicitly defined in order to
avoid interpretation by the analyst. As a consequence, the reliability of
Interlaboratory results will be enhanced; this requirement is mandatory for
any standard method. For example, the agitation methods are quite susceptible
to interpretation by the analyst. If the shaking apparatus and agitation rate
are rigidly defined, then much of the variability in the leachate results could
be eliminated. The agitation method should expose all of the waste material
to the leaching medium to give an indication of the maximum quantities which
would be extracted under the test conditions. It does not appear that using
a reciprocating shaker, as suggested by ASTM, achieves this goal. The agita-
tion method should also be able to leach wastes in 2-liter quantities and larger
quantities as required for bio-testing.
The separation of complex, multiphase industrial wastes prior to leach-
ing has not been adequately covered by any of the methods reviewed in this
study. A separation scheme similar to that suggested by Ham2 could be
adopted. In this scheme, a series of decisions on separation is made, based
on the nature of the waste. Both filtration and centrifugation are used to
separate phases.
Sample preparation, or whether to use the waste in its disposed form,
is another question which needs to be addressed. If the waste is to be used
tn its disposed form, then provisions must be made for the treatment of wastes
of large masses which are not conveniently extracted in the laboratory.
Should the laboratory procedure be adapted to the dimensions of the waste,
or should the size of the waste be reduced (while reducing the surface area
proportionally) to make it suitable for a small scale laboratory experiment?
In addition, a protocol for preserving the sample for subsequent anal-
yHes must be included in the standard leachate test. Also, the holding
time of the preserved sample must be stated in the procedure. For inorganic
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species, this would include acidification of the leachate prior to AAS analysis.
For some ecological tests, a pH adjustment of the leachate to pH 6.5 to 8.5
may be necessary.
Finally, the objectives of the leachate test must be given primary consid-
eration. The objectives of the test define both the type of information
ought and the possible conclusions that may be reached. A test could, for
example, attempt to simulate acid rain conditions, anaerobic degradation or a
host of other disposal situations. The EA protocol provides for characteriza-
tion of solid wastes in terms of inorganic composition. Since these data can
always be used to make worst case predictions, the leachate tests should depict
the more frequently encountered or typical situation; a single test cannot
simulate the general case. Ostensibly this criterion suggests a low pH leach-
ing medium.
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SECTION 4
OVERVIEW OF LEACHATE PROBLEM
BACKGROUND
In an effort to predict the environmental impact of solid waste disposal,
a routine leachate test is needed to characterize the leaching properties of
a waste material. This concern with a waste's leaching properties adds a new
dimension to environmental assessment measurement programs. Designing a
leachate procedure, which can be routinely applied in the laboratory, becomes
the key factor in solving this problem. The objectives of the standard leach-
Ing test should be explicitly addressed to ensure proper interpretation of the
test results. The interpretation of the test results must not extend beyond
the limits established by the test objectives. The experimental procedure
must be described in detail to prevent interpretation by the analyst and to
facilitate comparisons of interlaboratory data. Although some studies have
addressed the leachate generation problem, a single procedure, which satisfies
all of the needs of an Environmental Assessment (EA) Program, has not been
Identified. The adoption of a standard leaching test is one requirement of
the Resource Conservation and Recovery Act.
A major objective of the Resource Conservation and Recovery Act of 1976
(RCRA, P.L, 94-580) is to "regulate the treatment, storage, transportation,
and disposal of hazardous wastes which have adverse effects on health and the
environment." Congress recognizes that a potential problem has developed with
the increase of waste material discarded by the public and private sectors.
Additionally, an outcome of future technological advancement may be the pro-
duction of waste materials with chemical and physical characteristics not en-
countered previously, thus presenting subsequent disposal problems. In an
effort to solve these disposal problems, RCRA also provides for the "promul-
gation of guidelines for solid waste collection, transport, separation, recov-
ery, and disposal practices and systems."
The Environmental Protection Agency (EPA) has been designated to provide
the above guidelines. Criteria for identifying the characteristics of the
hazardous waste are to be Included in these guidelines. As defined by EPA-
OSW, a waste Is hazardous If it meets any one of the following criteria:
Flammable
Corrosive
Reactive
Toxic
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Infectious
Radioactive
Contains mutagenic, carcinogenic, or teratogenic substances
Contains substances that bioaccumulate
Contains toxic organic substances
Identification methods to determine whether a waste meets any of the
previous characteristics have been proposed by EPA. A waste is defined as
toxic, hence hazardous, if the leachate concentrations of any of the contami-
nants listed below exceed the values in Table 1.
TABLE 1. LIST OF TOXIC SUBSTANCES
Concentration in Extract
Contaminant (mg/1)
Arsenic (As)
Barium (Ba)
Cadmium (Cd)
Chromium (Cr)
Lead (Pb)
Mercury (Hg)
Selenium (Se)
Silver (Ag)
Endrin
Lindane
Methoxychlor
Toxaphene
2,4-D
2,4,5-TP
0.50
10.0
0.10
0.50
0.50
0.02
0.10
0.50
0.002
0.040
1.0
0.050
1.0
0.10
These leachate threshold levels are equal to 10 times the EPA National Interim
Primary Drinking Water Standard for these substances.
OBJECTIVES
Although the routine analysis of a leachate from a waste material can
serve as a basis for defining toxicity, any effort to predict the long-term
effects on the environment after disposal is extremely difficult. It would be
desirable in any proposed leachate procedure to simulate the environmental
conditions to which the waste will be exposed. However, any attempt to model
the environmental conditions in the laboratory may be unrealistic.
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Since a standard leaching method does not presently exist, the Process
Measurements Branch (PMB) of EPA's Industrial Environmental Research Labora-
tory (IERL) at Research Triangle Park (RTF) is directing research to identify
a leachate generation procedure suitable for Environmental Assessment (EA)
programs. In conjunction with this effort, four leachate generation
methods have been evaluated. The objective of the study was to evaluate the
methods based upon the following criteria:
1. General Applicability
2. Reproducibility
3. EA Methods Compatibility
4. Leaching Characteristics
Any leachate procedure selected for environmental work must be applicable
to a wide range of waste materials. With the emphasis on energy systems, the
wastes being used to evaluate the procedures include those from conventional
and advanced energy processes. The type of wastes leached in this project
include oil shale tailings, fluidized-bed combustion waste, bituminous coal
fly ash, bituminous coal boiler slag, lignitic coal scrubber sludge, and
hopper ash from a coal-fired power plant. If a standard leaching test is de-
sired, then the reproducibility of the procedure must be known to facilitate
comparisons of future interlaboratory results. The reproducibility of the pro-
cedures was determined from the analyses of replicate extractions. The leachatea
generated by each procedure must show a compatibility with both chemical and
logical EA methods. The leaching procedures are also evaluated for their
leaching characteristics as an indication of the quantities extracted by each
of the leachate methods.
The leachate generation procedures evaluated by GCA include:
EPA-OSW Extraction Procedure (EP) an acetic acid extraction
American Society for Testing and Materials Method A (ASTM-A)
a water extraction
American Society for Testing and Materials Method B (ASTM-B)
an acetic acid-acetate buffer extraction
Carbonic Acid Extraction (CAE) an extraction with CC>2-
saturated water
The experimental parameters for these methods are compared in Table 2. These
procedures are discussed below.
Extraction Procedure
The EP method has been proposed by the EPA-OSW to meet the RCRA guide-
lines in evaluating the hazards of solid waste disposal. With the addition
of acetic acid to the aqueous solution, the procedure presumably intends to
simulate the first stage of anaerobic degradation, involving the formation of
10
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TABLE 2. COMPARISON OF EXPERIMENTAL PARAMETERS FOR THE ASTM-A,
ASTM-B, EP, AND CAE LEACEATE METHODS
Parameter
Leaching Medium
Minimum Sample
Size
Sample
Preparation
Solid-to-liquid
Ratio
Agitation
Method
Agitation Time
Initial pH of
Leaching
Solution
Number of
Extractions
Temperature
ASTM-A
ASTM Type IV
H20
350 grains
None; use in
disposed form
1:4
Reciprocating
shaker
recommended
48 hours
5.6-5.9
1
Room
ASTM-B
Sodium Acetate
Acetic acid
Buffer
350 grams
None; use in
disposed form
1:4
Reciprocating
shaker
recommended
48 hours
4.5
1
Room
EP CAE
0.5 N acetic acid CO2- saturated H20
100 grams 100 grams
Grind or subject to None; use in disposed form
structural integrity test
1:20 1:16
Unspecified extractor; Reciprocating shaker
stirring device suggested recommended
24 hours 48 hours
5.6-5.9 3.9-4.0
1 1
Room Room
-------
volatile, organic acids at a disposal site. The acidic medium also provides
a more aggressive leaching test than the purely aqueous leachate.
The experimental procedure suggests a minimum size of 100 grams for the
extraction. The separation of any liquid fraction from the original sample is
accomplished by filtration or centrifugation methods. After separation, the
solid portion is prepared for extraction either by grinding the solid to pass
through a 9.5 mm standard sieve or by applying the structural integrity test.
After sample preparation, the solid is placed in an extractor that must
be capable of thoroughly mixing the solid and the leaching medium. A stirring
device is suggested, but other agitation methods may also be used. An amount
of deionized water equal to 16 times the weight of sample is added. The pH of
the resulting leachate is monitored, maintained at 5.0 ± 0.2 and adjusted with
0.5 N acetic acid, if necessary. The extraction proceeds for 24 hours with a
maximum addition of 4 ml of acid per gram of sample permitted to maintain the
PH.
After 24 hours, the mixture is filtered and deionized water is added to
adjust the volume to 20 times the weight of the sample. The analysis of metals
follows the flame atomic absorption methods in "Methods for Chemical Analysis
of Water and Wastes," Environmental Protection Agency, Office of Technology
Transfer, Washington, D.C. (1974).
American Society for Testing and Materials Methods
ASTM has proposed two procedures to determine the leachable components of
a solid waste. Both methods are "intended as a rapid means of obtaining a
solution for evaluation of the extractable materials in wastes. They may be
used to produce solutions for the estimation of the relative environmental
hazard inherent in the leachings from the waste." Each method is intended "to
determine collectively the immediate surface washing and the time-dependent,
diffusion-controlled contributions to leachings from the waste." The wastes
are to be used in the form in which they are disposed. Where available, sam-
pling is to proceed using ASTM sample methods developed for the specific
industry.
The water extraction (ASTM Method A) uses Type IV water for the extrac-
tion, while the ASTM Method B employs an acetic acid-acetate buffer solution
to leach the metals from the wastes. The experimental procedure, however, is
Identical for each method. A minimum sample size of 350 grams is recommended
for each method. A smal] portion of the sample is dried at 104 ± 2°C for 18
1 2 hours to determine the moisture content of the sample. The quantity of
sample chosen for leaching is placed in a round, wide-mouthed bottle (constructed
of material appropriate for the solid waste and subsequent analyses) and mixed
with the \lyO or acetate buffer. The volume, in milliliters of leachate added,
is equal to four times the weight in grams of the sample. Mixing of the
phases is accomplished by any apparatus that is capable of producing the con-
stant movement equivalent to a reciprocating shaker operated at 60 to 70 1-inch
cycles per minute. Agitation is continued for 48 hours, followed by vacuum
filtration of the liquid phase. The leachate is to be preserved in a manner
consistent with the analytical techniques. The results of the analyses are
presented in milligrams leached per gram of dry sample.
12
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Carbonic Acid Extraction
CAE was Introduced as an alternative to the acidic leaching media of the
previous methods. The C02-saturated water was intended to simulate the aggres-
sive leaching characteristics of the acetic acid and acetate buffer solutions
without having the toxicity problem associated with the bioassay tests.
In order to maintain a C02~saturated leachate, the extraction must be
performed in a closed system. Thus, the CAE followed the basic procedure and
agitation method of the ASTM methods. A minimum sample size of 100 grams is
suggested for the extraction. Round, wide-mouthed linear polyethylene bottles
are used to contain the leachate. The liquid-to-solid ratio is 16:1 and was
chosen to minimize common ion effects, which may affect the solubility of
some species in the leachate. It vas also hoped that this liquid-to-solid
ratio would be low enough to prevent the trace elements from being diluted
below the AAS detection limits.
The carbonic acid solution is prepared by bubbling C02 through deionized
water until the pH reaches a minimum (approximately 3.9 to 4.0). To compare
variations of the procedure, the mixture was agitated at the slower rate ad-
vocated by the ASTM methods (60 cycles/minute), and at twice that rate.
After shaking for 48 hours, the leachates were filtered and aliquots were
removed and preserved for atomic absorption and ion chromatographic analyses.
GENERAL CONSIDERATIONS FOR LEACHATE GENERATION
An ideal leaching test should take into account the pH, buffer capacity,
redox potential, temperature, ionic strength, organic constituents, and bio-
logical activity of the environment in which it is to be disposed. Since
these parameters are expected to be site-specific, developing a standard
leaching test to incorporate these variables is impractical and certainly
could not be achieved by a single leaching procedure. These theoretical
aspects of leachate generation are reviewed in a Mitre Corporation report
that compares several leachate test methods.3
The determination of the factors that govern the release of a species
from a waste has been used to define the objectives of a leaching test.2
These factors have been Identified as:
1. The highest concentration of a species found in the leachate
2. Factors controlling the above concentration
3. Total amount of a species available from a given waste
4. Rate of dissolution of a species.
A comprehensive leaching test and analysis would be needed to make these
determinations. This detailed study of the leachate would certainly be very
useful, but its applicability as a basis for a standard leaching test is
limited. The expense (both time and monetary) of doing this type of test on
a routine basis for a variety of waste materials would be prohibitive.
13
-------
Contrary to the comprehensive leaching test, the standardized leaching
method should be a simple, cost-effective, expedient means of assessing the
hazards of solid waste disposal. The test conditions in the standardized test
should be invariable and rigorously defined. This not only minimizes any
"interpretation" of the procedure, but also defines the type of information
yielded by the experiment. A properly designed test can provide in a short
time the data needed to determine the leaching characteristics of a waste.
These short, standardized procedures can be classified as shake (or
batch) tests, column tests, and field cell tests. In a shake test, the solid
material and leaching solution are mixed in a container, agitated under pre-
determined conditions, and the liquid phase is analyzed. The shaking apparatus
should be capable of exposing all of the solid waste to the leachate, without
altering the physical nature of the solid. A reciprocating shaker, wrist-
action shaker, rotating shaker, etc., can provide the necessary agitation.
This type of test can yield data about the equilibrium concentrations of
species in the leachate, and the kinetics of the process, if aliquots are with-
drawn and analyzed periodically.
A column test allows the leaching medium to flow through the waste mate-
rial, which is supported in a column. The design of the column test readily
yields kinetic information about the leaching process, since the eluent con-
tacts the solid for short time periods and attempts to simulate the permeabil-
ity of the waste in a landfill situation. Column tests may not be compatible
with the physical form of the solid waste. However, the major disadvantages
of this test are the time required to acquire results, which may range from
months to years, and the poor reproducibility inherent in the method, which
can be caused by channeling in the column.
As scale models of actual waste disposal sites, the field cell tests are
the most ambitious in mimicking environmental conditions. The test suffers
the limitations that the information resulting from the test is applicable
to only that site modeled, and is expensive and time-consuming.
The shake test, then, appears to fulfill the need for a short, inexpensive,
standardized leaching test that can be routinely applied to a wide range of
waste materials.
FACTORS AFFECTING CONCENTRATION IN LEACHATES
The concentration of a constituent in the leachate is governed by the
factors listed below. Some of these parameters have been outlined previously2
and will be reviewed briefly here. Consideration of these variables is impor-
tant in the design of a standard leaching procedure.
1. Sampling and sample pretreatment
2. Composition of leaching medium
3. Solid to liquid ratio
4. Time per elution
5. Number of elutions
14
-------
6. Temperature
7. Agitation method
8. Sample preservation
9. Analytical methods
Sampling and Sample Pretreatment
One of the greatest sources of variability in the leachates is caused by
the composition and nature of the sample. Obtaining a homogeneous sample is
difficult to achieve, and the situation is complicated by the variation in
the chemical composition of the solid caused by changes in raw materials and/
or plant operating conditions. These latter problems are inherent in the
process and the variation in the results caused by the situation must be
tolerated. However, an explicit and comprehensive sampling procedure could
ensure a sample of greater homogeneity.
Treatment of the sample prior to generating the leachate can also alter
subsequent results. Provision has been made in some of the proposed methods
for separating solid and liquid phases and for determining the physical state
In which the solid waste is to be leached. It would seem reasonable that a
solid be extracted in the physical form in which it is disposed. Some leachate
generation methods grind the sample or subject it to a structural integrity
teat (EPA-OSW method). This alteration will increase the surface area exposed
to the leaching medium and artificially increase the concentrations of species
in solution. A sample that has been physically changed may not give a true
indication of its leaching effect upon the environment after disposal.
Composition of Leaching Medium
Probably the single most important parameter in the leaching procedure is
the chemical composition of the leaching medium. Once the type of disposal or
environmental conditions to be simulated by the leaching method are defined,
then a suitable leaching medium can be designed to achieve this goal.
Present methods use acetic acid or acetate buffer solutions to control pH
under acidic conditions and simulate anaerobic degradation, in which volatile
fatty acids are produced. Extraction of the waste with distilled-deionized
water uses milder leaching conditions in an effort to determine the effect of
uncontaminated rainwater upon the sample. Ham, et al.,2*1* have developed the
most rigorous leaching medium to simulate an actively decomposing municipal
landfill- The parameters of pH, buffering capacity, redox environment, com-
plexing capacity, and ionic strength are incorporated into the chemical make-
up of the eluent.
The leaching medium alone can determine the validity of predicting the
environmental effect of a waste material after disposal. It is also the most
difficult parameter to define experimentally.
15
-------
-to-Solid Ratio
Since the llquid-to-solid ratio varies in a natural system, the ratio
used in the laboratory must be based upon a few considerations. A high
liquid-to-solid ratio will yield an increase in the number of species leached,
although the concentration of each species may be lower. This reduced concen-
tration could be an analytical problem if the result is below the detection
limit. Conversely, a low ratio will increase common ion effects with only the
most soluble species being leached. Detection of species may not be a problem,
but the total amount of species leached may not be indicative of the natural
system. Ratios range from 4:1 to 16:1 for the leaching methods examined in
this project.
Time per Elation
The concentration of a substance in solution is determined not only by
the liquid-to-solid ratio, but also by the time allotted for extraction. For
kinetic data, the concentration can be monitored by removing aliquots of the
leachate at specified periods.
Equilibrium data may be easier to obtain in a shake test, although
steady-state conditions may be achieved by only a few of the species in the
leachate, since the equilibrating times will differ for the various constit-
uents. This situation is not necessarily a problem because it is unlikely
that equilibrium is ever reached in a landfill situation.
In designing a leachate procedure, an elution time should be chosen
which allows the system to approach a steady-state condition. The elution
time should be short enough, though, to be routinely performed in the labora-
tory. Most of the present methods utilize an extraction period of 24 to 48
hours.
Number of Elutions
The number of times the solid is extracted can be related to the amount
of material released during the leaching process. This information may give
a more realistic indication of a waste's disposal behavior. Obviously, the
repeated elutions require more laboratory work, and this must be justified by
the additional information gained by multiple elutions. Most of the methods
currently used employ only one elution of the sample.
Temperature
The temperature of the extraction affects the solubility and the rate at
which Hubstances will be released from the solid. Modeling the temperature in
a landfill is difficult, since it varies with seasonal changes. Ambient lab-
oratory temperature is usually chosen as a convenient compromise to the problem.
Agitation Method
The means of exposing the solid to the leaching solution has already
been mentioned in the general description of a shake test. To reiterate, the
16
-------
agitating apparatus should be capable of mixing the two phases thoroughly
without altering the physical nature of the sample. If the surface area of
the sample is increased during shaking, then increases in species concentra-
tion and rate of dissolution would be expected. Experimental results would
have to be interpreted with respect to these developments.
A number of shaking apparati can be and have been used for the leaching
procedures, including reciprocating shakers, rotating drums and a stirring
device (EPA method). For a standardized procedure, the important point is to
specify exactly the method of agitation to be used.
Sample Preservation
Prior to preservation of the sample, the solid and liquid phases must be
separated. The method of separation could have a significant influence upon
the results obtained during analysis. Filtration with a filter pore size
greater than 0.45 ym allows colloidal particles (e.g., ferric hydroxide) to
pass through the filter and remain suspended in the filtrate. The presence of
colloidal particles could cause fluctuations in the data from atomic absorption
analyses, implying a greater nonreproducibility in the method. Centrifugation
of the mixture also fails to remove colloidal matter. Filtration through a
pore size of 0.45 pm or less removes these colloids and bacteria and aids in
achieving a filtrate of uniform composition.
Sample preservation should be an integral part of the leachate procedure.
It is generally acknowledged that trace metals in solution are preserved at
pH < 2 by the addition of nitric acid with storage in a linear polyethylene
bottle. The amount of nitric acid required to lower the pH to 2 will vary
with the buffer capacity and inherent pH of the leachate from each waste.
For the EP and two ASTM procedures, sample preservation is not mentioned or
is poorly defined.
For the anionic analyses by ion chromatography, the EPA recommends re-
frigeration at 4°C with a maximum holding time of 7 days.5
Analytical Methods
In a standardized leaching test, the analytical methods selected for
quantitation of the toxic substances should be readily available to the aver-
age laboratory at a reasonable cost per sample. Atomic absorption has been
chosen for metal analyses because of its widespread use. Atomic absorption
was compared with five other instrumental methods for metal analysis,1 includ-
ing isotope dilution-spark source mass spectrometry, spark source mass spec-
trometry, inductively coupled plasma emission spectrometry, optical emission
spectrometry, and neutron activation analysis. The results of the study in-
dicate that AAS is comparable to the other methods for metals analysis. In
performing the AAS analyses, the analyst must ensure that the data are not
artifacts of interferences from the matrix. This can be determined by using
the method of standard additions or by analyzing quality control samples.
17
-------
SECTION 5
LITERATURE REVIEW
PREVIOUS REPORTS
This section will attempt to summarize the work on leachate methods per-
formed prior to this project. Some of these reports deal with methods com-
parisons, while others discuss the results of applying those methods to solid
wastes.
1. "Compilation and Evaluation of Leaching Test Methods,"
W. Lowenbach.
The initial portion of the report presents the theoretical
considerations in selecting a leachate procedure. The theo-
retical aspects of thermodynamic relationships, including a
dynamic model for leachate systems and kinetic considerations
which include temperature, ionic strength, chemical effects,
pH, buffering, organic constituents, and redox reactions as
applied to leachates are addressed.
The majority of the discussion centers on a compilation and
assessment of 30 laboratory shake tests. The originator of
the test is listed along with the experimental parameters
covered by the test, a brief description of the procedure,
and advantages and disadvantages of the test (based on the
theoretical considerations), and the purpose of test, as
defined by the originator.
Three tests are recommended for further investigation:
(a) The IUCS shake test - uses water obtained at the
disposal site for the eluent with a 4:1 liquid-
to-solid ratio and an agitation period of 48 hours;
(b) Minnesota Shake Test - the waste is shaken with
acetic acid buffer at a 40:1 liquid-to-solid
ratio for 24 hours;
(c) University of Wisconsin Synthetic Leachate Test -
the leaching medium incorporates the theoretical
parameters discussed in the report with a shaking
time of 24 hours, and a 7:1 liquid-to-solid ratio.
18
-------
2. "Comparison of Three Waste Leaching Tests,"
R.K. Ham, et al.1*
The three tests recommended for further study in the pre-
vious report were compared in detail in this work. Asso-
ciated with this study is the preliminary investigation
leading to the development of the synthetic leachate test.2
The methods comparison is also reviewed in an Executive
Summary.6
The synthetic leachate test uses several types of leaching
solutions depending upon the landfill situation to be modeled.
For a stabilized municipal landfill or monolandfill, dis-
tilled, deionized water is the leaching medium. If the waste
is disposed with other industrial wastes, then distilled,
deionized water along with other eluents appropriate for
simulating disposal site conditions is used for leachate
purposes.
The composition of the synthetic leachate (Table 3) is
designed to simulate the first stage of anaerobic degrada-
tion of an actively decomposing municipal landfill in which
volatile organic acids and C02 are produced. The pH in this
phase is reduced to 4.5 to 5 and modeled in the leachate by
the acetate buffer. The glycine is included to demonstrate
the complexing ability of organic nitrogen in the leachate.
The redox potential of the leachate is controlled by the
iron (Il)-pyrogallol complex, with the pyrogallol also
serving as an additional chelating agent. The Na and
ions in the synthetic leachate aid in controlling the ionic
strength of the solution.
These leaching solutions are applied to two procedures to
determine the maximum release (Procedure R) of the waste or
the maximum species concentration (Procedure C). Procedure R
uses three elutions of the same waste material at a 1:10 solid-
to-liquid ratio to estimate the maximum release of a species
from the waste material. After each elution, the filtrate
is removed and analyzed and fresh leachate is added. In
Procedure C, the waste is removed and discarded after each
of the three elutions. A portion of the leachate is removed
for analysis, while the remainder is returned to leach a
fresh sample of waste.
The data from the synthetic leachate test were compared with
the results of the IU Conversion Systems modified 48-hour
shake test (1UCS test) and the test of the Minnesota Pollu-
tion Control Agency (Minnesota test). A comparison of the
test procedures is outlined in Table 4. The three tests were
applied to 14 industrial wastes ranging from adhesive and
paint wastes to electroplating sludge. The inorganic param-
eters analyzed for the comparison included Na, K, Mg, Zn, Fe,
19
-------
TABLE 3. CHEMICAL COMPOSITION OF UNIVERSITY OF
WISCONSIN'S SYNTHETIC MUNICIPAL LAND-
FILL LEACHATE
Concentration
Chemical
0.15 M Acetic acid
0.15 M Sodium acetate
0.050 M Glycine
0.008 M Pyrogallol (1,2,3-trihydroxybenzene)
0.024 M Ferrous sulfate
Note: pH of Leachate = 4.5
TABLE 4. COMPARISON OF THREE LEACHING TESTS
Parameter
Leaching
solution
Solid-to-Liquid
Ratio
Shaking
technique
Time per
elution
Number of
elutions
Synthetic
leachate test
Synthetic leachate,
H20b
1:10 (Process R)
Varied (Process C)
Slow tumbling at
3 rpm
24 hours
3 or more
IUCS test
H20b
1:4
Back and
forth
shaking
48 hours
5
Minnesota test
Acetate buffer,
H20b
1:40
1 min. shake,
24 hour rest
24 hours
1
Temperature
Room
Room
Room
From Reference 4.
Distilled, deionized water.
20
-------
Cu, Pb, Cd, and Cr. The selection of trace metals to be
analyzed was based upon the nature of the particular waste.
Determination of COD in each leachate gave an indication
of the quantity of organic matter present. Some leachates
were analyzed by GC-MS for specific organic compounds. The
pH and conductivity of each leachate were also measured.
The analyses (Table 5) revealed that the design of the syn-
thetic leachate test (including both the synthetic leachate
and HaO) yielded the highest concentrations and highest
release of inorganic parameters among the tests. In com-
paring the leaching media, the synthetic leachate was the
most aggressive for extracting the metals from the wastes.
The synthetic leachate gave the highest concentration
74 percent of the time (52 percent for Procedure C and
22 percent for Procedure R) for parameters measured in both
acidic and HaO leachates. As might be expected, the acidic
solutions as a whole were more effective then H20 for
leaching the inorganic species. The acidic leachates gave
the highest concentrations of inorganic species 89 percent
of the time and the highest release 96 percent of the time.
The reproducibility of the synthetic leachate test was de-
termined using nine replicates of leachates from a paint
waste generated by both Procedure R and Procedure C (Table 6).
The relative standard deviations were less than 15 percent
for K, Mg, Pb, Fe, and Zn using Procedure R (maximum release).
However, standard deviations were generally higher for the
same metals from Procedure C (maximum concentration). The
variation in the Zn and Fe data was especially high. No
explanation was given for the Zn results, but the Fe data
indicated that Fe was precipitating out of solution with
successive elutions.
One of the problems in applying the synthetic leachate to the
Environmental Assessment Program is the toxicity of the leach-
ing medium to bioassay tests. Another limitation for its
use as a standard leaching test is the care required by the
analyst to handle the leachate. The iron-pyrogallol complex
is air sensitive and could oxidize and form a precipitate if
exposed to air during the procedure. To avoid this, con-
tainers should be purged with N2 and filtering should be done
in a dry box under a nitrogen atmosphere. If these precau-
tions are not taken, the precipitation of the Fe-pyrogallol
complex could cause the coprecipitation and adsorption of
some species in solution. A nonaerobic leachate has been de-
veloped by the same researchers to avoid this problem, but it
contains no ferrous sulfate and does not model the redox
capacity of the landfill. It also contains the acetate buffer
and thus retains its toxicity to bioassay tests.
21
-------
TABLE 5. THE NUMBER OF TIMES ACID OR H20 LEACHING
SOLUTIONS GAVE HIGHEST CONCENTRATIONS OR
RELEASE OF AN INORGANIC PARAMETER FROM
A WASTE3
(Only for Parameters Measured in Both
Acid and H20 Leachates)
SLT Minn. IUCS Total
Acid(SL) H20 Acid H20 H20 Acid H20 Total tests
Number of Times Giving Maximum Concentration
K
Mg
Zn
Pb
Cu
Cd
10 1
811
11 2
2 4
2 1
1
1 10
9
13
6
1 2
1
/. i
2
1
0
0
2
0
c
12
10
13
6
4
1
7Tb
Total, % 89 11
Number of Times Giving Maximum Release
K
Mg
Zn
Pb
Cu
Cd
8
8 1
8
1
1
2
4
2
4
5
2
1
12
10
12
6
1 3
3
0
1
0
0
1
0
12
11
12
6
4
3
46 2 48
Total, % 96 4
rt
From Reference 4.
Totals are not equal because two tests may both give
the maximum concentration but have different maximum
releases. In cases where the maximum concentration
or release were the same, the results were not
tabulated.
22
-------
TABLE 6. STANDARD DEVIATION CALCULATIONS FOR MULTIPLE REPLICATES OF PAINT WASTE
LEACHED WITH SYNTHETIC LEACHATE USING SLT PROCEDURES3
Procedure R
Param-
eter Day
K
Mg
Zn
Pb
Cu
Fe
1
2
3
1
2
3
1
2
3
1
2
3
1
2
3
1
2
3
(N
Mean
value
3.
2.
1.
9.
1.
0.
16.
3.
1.
0.
0.
0.
b.d.
b.d.
b.d.
1180.
1166.
1094.
86
10
58
9
4
51
92
40
44
52
27
22
c
- 9)
0
0.
0.
0.
0.
0.
0.
1.
0.
0.
0.
0.
0.
87.
80.
58.
16
22
18
87
07
03
31
23
08
02
02
04
%
4.1
10.7
11.6
8.8
4.9
6.1
7.74
6.8
5.4
4.4
8.2
17.2
7.4
7.0
5.6
Procedure C
(N - 9)
Mean
value
4.00
6.49
10.50
8.6
16.3
33.
22.68
70.5
123.
0.50
0.93
1.32
b.d.
b.d.
0.32
1123.
904.
585.
0
0.
1.
0.
0.
2.
7.
10.
22.
51.
0.
0.
0.
0.
71.
146.
204.
17
84
49
69
3
5
33
5
03
14
18
09
%
4.3
28.3
4.7
8.1
14.0
22.7
45.6
31.9
41.3
6.0
15.4
13.8
28.3
6.4
16.3
35.
Both procedures
Day lb
Mean
value o 7»
3.93 0.17 4.7
9.3 1.1 11.9
19.4 7.8 40.
0.51 0.025 5.0
1152. 80. 7.0
*From Reference 4.
bgn j)ay 1, procedures C and R are the same,
cb.d. " below detection.
23
-------
Several significant results obtained during the course of
the Wisconsin investigation are highlighted below:
(a) A widely-applicable liquid-solid separation scheme
was developed. Anything that will not filter
thro.ugh a 0.45 urn filter or separate during cen-
trifugation is considered a solid and is used in
the leaching test.
(b) Five agitation methods, including continuous
shaking with a Gyrotory shaker, stirring
with a mechanical paddle, intermittent shak-
ing by hand, swing type shaking, or using a
rotating disk shaker, were tested and results
indicated that all methods provided nearly
equal release.
(c) For the same wastes, cumulative release varies
for times 24 hours or more, indicating that the
effect of reaction time for periods greater
than 24 hours is not consistent. Systems do
not appear to reach equilibrium within a 24- to
72-hour period.
(d) For some wastes, multiple elutions indicate
that steady-state conditions may continue
over a very long time period.
(e) The amount leached from fly ash after 18 elu-
tions ranged from 0.07 to 7 percent for Na and
Fe, respectively, compared to the amount ob-
tained by total digestion of the fly ash.
(f) Agents added to inhibit bacterial action (Ag,
NO3, Thymol, and CuSOit) exhibited no consis-
tent effect on the test results. For the wastes
tested, bacterial action had little effect on
the leaching characteristics within the time
frame of the test.
3. "Trace Element Characterization of Coal Wastes -
Second Annual Progress Report," E.M. Wewerka, et al.7
High sulfur coal cleaning wastes from the Illinois Basin
were subjected to leaching tests to determine the trace
element levels in the drainage from the coal refuse dumps.
The coal refuse samples were composed of clay minerals,
quartz, pyrite, and raarcasite.
The shake tests, with distilled water for the leachate,
revealed that the amount of dissolved solids increases
as the pH of the leachate decreases. The pH of the
24
-------
leachates is largely determined by the oxidation of pyrite
and marcasite in the samples.
FeS2 + A02 + H2 -* FeSOi* + H2SOi,
High percentages of iron, calcium, manganese, cobalt,
nickel, zinc, and cadmium were leached from the refuse
samples under all of the experimental conditions used.
Thermodynamically, all of these elements (except cal-
cium) have a tendency to exist as sulfides in the samples.
It was also observed that changes in surface area of the
refuse produce little change in the leaching characteris-
tics of the sample. This is indicative of a heterogeneous
reaction, whose rate is controlled by a diffusion process.
Thus, the rate of acid formation and solids dissolution
would be determined by the movement of reactants to the
sample surface or products away from the surface.
The coal refuse samples were also subjected to column
leaching studies using distilled water for the leachate.
The data from these tests show that the greatest release
of trace elements occurs during the early contact of the
leachate with the solid. Several elements, such as cobalt,
nickel, cadmium, manganese, and zinc were rapidly leached
from the refuse and were classified as "environmentally
active." A second column test used discontinuous flow
of the solution through the solid. This experiment was
designed to simulate the intermittent contact of some
dumps with surface or ground waters.
When the leachate flow is halted and the material is
allowed to dry out, the refuse material is regenerated
and, when leaching is resumed, large amounts of acid
and dissolved salts are released again. This implies
that disposal areas, which experience seasonal variations
in precipitation, may contaminate the environment to a
greater extent than a disposal site in constant contact
with water.
4. "Toxicity of Leachates, Interim Progress Report,"
(April 1, 1978 to January 1, 1979), J.L, Epler, et al.1
Personnel at Oak Ridge National Laboratory have extracted
several wastes (fly ash, scrubber sludge, bottom ash, and
soybean process cake) using the Extraction Procedure rec-
ommended by EPA. The extracts were subjected to various
bioassays to evaluate their toxicity. The effect of the
acetic acid medium upon the bioassay tests was also
investigated.
25
-------
During the course of the project, the analysis of trace
metals by AAS was compared with five other instrumental
methods, including isotope dilution-spark source mass spectrom-
etry (ID-SSMS), inductively coupled argon plasma emission
spectrometry (ICAPS), optical emission spectrometry (OES),
and neutron activation analysis (NAA). The data for these
methods are compared in Table 7. As indicated in Table 7,
the AAS data compared favorably with the results of the
other methods. Since AAS instrumentation is available in
most laboratories, it was recommended as the method to
quantitate the trace metals in the extracts.
The results of the inorganic analyses for the EP leachates
are presented in Table 8. The results for an arsenic-
contaminated groundwater sample are included in the table.
The arsenic-contaminated groundwater sample would be con-
sidered toxic, based on the RCRA criteria. The arsenic
and cadmium levels exceed the level of 10 times the EPA
Primary Drinking Water Standard allowed for each element.
The cadmium value for the fly ash leachate equals the
threshold level, and this extract could be labeled toxic.
The effects of the extracts on the bioassay tests was
difficult to determine because of the low concentrations
of organic constituents. Methods for concentrating and
separating the organics present in the extracts were
investigated. Solvent extraction with methylene chloride
or cyclohexane was compared with concentration by XAD-2
resin. Methylene chloride proved to be the most effective
solvent for concentrating and extracting the organic species
from the EP extract, but methylene chloride may cause
problems with the bioassays. The use of XAD-2 was
selected as the most cost-effective means of preparing
the organic concentrates, since the extraction of several
leachates can be conducted simultaneously with a peristaltic
pump.
After concentrating the organic components, the nonpolar
compounds are separated from polar species by column chrom-
atography using Florisil. The nonpolar compounds are
separated further on alumina into a monoaromatic fraction,
a diaromatic fraction, a polyaromatic fraction, and a
heteroaromatic fraction. These fractions can then be
tested separately for their effects on the bioassay tests,
and the toxicity in the leachates can be attributed to a
specific class of organic compounds.
5. "Technical Aspects of the Resource Conservation and Recovery
Act Upon Coal Combustion and Conversion Systems,"
U.W. Weeter, et al.a
As part of the program, the literature was surveyed for the
metal concentrations found in the reactants and products
26
-------
TABLE 7. COMPARISON OF METALS ANALYSES FOR SEWAGE SLUDGE EP EXTRACT3
M
Average concentration ± S.D. (rag/liter) for method**
Metal
Ag
As
Be
Cd
Cr
Cu
Hg
Ni
Pb
Sb
Se
Tl
Zn
AAS ID-SSMS SSMS ICAPS OES
0.0002 ± 0.00001 - <0.02 <0.02 -
0.03 ± 0 - <0.02 - -
0.0004 ± 0.00002 - - - <0.1
1.2 ±0 1.1 ± 0 - 0.08 ± 0.08 -
0.03 ± 0.0008 <0.2 - <0.5 -
0.7 ± 0.01 0.75 ± 0.07 - 0.7 ± 0.07 -
0.00003 ± 0.000001 -
3.4 ± 0.2 4.1 ± 0.27 - 3.0 ± 0.3
0.03 ± 0.003 <0.05 - <0.1 -
0.10 ± 0.002 - ~0.01 - -
<0.002 - £0.01 - -
0.01 ± 0.001 - <0.01 - -
36.7 ± 0.68 39.0 ± 2.2 - 45.0 ± 4.0
NAA
<0.01
0.08 ± 0.003
1.03 ± 0.03
0.06 ± 0.006
0.041 ± 0.005
<0.02
55 ± 1.5
From Reference 1.
AAS, atomic absorption spectrophotometry; ID-SSMS, isotope dilution-spark source
mass spectroscopy; ICPS, inductively coupled plasma emission spectrometry; OES,
optical emission spectrometry; NAA, neutron activation analysis.
-------
TABLE 8. TRACE ELEMENTAL ANALYSES OF As-CONTAMINATED GROUNDWATER
SAMPLE, EP EXTRACTS, AND BLANK3
N)
00
Concentration (mg/liter) in
EP extracts of
Element
Ag
As
Ba
Be
Cd
Cr
Cu
Hg
Ni
Pb
Sb
Se
Tl
Zn
F
As-contaminated
groundwater Fly ash
<0.01
412
<0.01
0.49
<0.01
0.01
<0.01
0.94
0.12
0.30
0.01
7.72
0.25
<0.01
<0.01
<0.50
0.01
0.10
<0.01
0.05
<0.01
0.66
<0.01
0.04
<0.01
0.02
1.55
8.00
Scrubber
sludge
<0.01
0.05
<0.50
<0.01
0.01
0.01
0.02
<0.01
0.14
<0.01
0.03
0.03b
0.01
0.24b
3.0
Bottom Soybean
ash process cake Blank
<0.01
<0.01
<0.50
<0.01
<0.01
<0.01
0.01
<0.01
0.02
<0.01
<0.01
<0.01b
<0.01
0.03b
<0.10
<0.01
<0.01
<0.50
<0.01
<0.01
<0.01
0.07
<0.01
0.02
<0.01
<0.01
<0.01b
<0.01
O.llb
<0.10
<0.001
<0.001
<0.500
<0.001
0.001
0.001
0.004
<0.001
0.013
<0.001
<0.002
<0.001
<0.001
0.283
<0.100
From Reference 1.
Single determination.
-------
of coal-combustion, coal-conversion processes. Metal con-
centrations were tabulated for coal, ash, char, tar, ash
slurries and leachates of the waste products. The energy
processes included coal combustion with electrostatic
precipitators, flue gas desulfurization, fluidized-bed
combustion, coal gasification, and coal liquefaction.
The acceptable metal concentrations in the leachates were
based on the 1962 Drinking Water Standards and the 1975
National Interim Primary Drinking Water Standards. Since
most of the leachate data in the literature was generated
by a distilled water extraction, the lower of the two
water standards was chosen for the maximum allowable metal
concentration in the leachates. It was thought that the
lower value would be more appropriate for this milder ex-
traction. The RCRA proposal uses a stronger acidic medium
and the maximum acceptable metal concentration, which is
10 times the 1975 drinking water standards, reflects this
more agressive leaching solution.
Table 9 reviews the leachate data for the energy wastes
studied in this program. If all of the leachate data found
in the literature for a specific waste exceeded the acceptable
level, then that waste was considered to have a definite
hazardous potential (denoted by an X in Table 9) with respect
to that element. The values in parentheses indicate the
dilution required to equal the drinking water criteria.
If only some of the leachate data exceeds the criteria,
then the waste is labeled as having a probable hazardous
potential with respect to that element. For leachate
data that never exceeds the criteria, the waste is classified
as having no hazardous potential.
As indicated in Table 9, dry disposal of fly ash poses the
greatest hazardous potential. Arsenic, cadmium, chromium,
copper, and lead showed definite hazardous potentials in
the leachates. Most of the wastes could be classified as
having a definite hazardous potential for at least one
element, and only the bottom ash leachate was classified
as a probable hazardous potential for all the elements
reviewed. Arsenic, cadmium, chromium, iron, lead, and
manganese exceed the criteria for most of the wastes tested.
6. "Evaluation of the Procedures for Identification of Hazardous
Waste," Interim Report, E.P. Meier, et al.9
The objectives of this ongoing study are to evaluate the
sampling, extraction, and analytical procedures proposed
in the RCRA regulations. The 11 sites sampled include
waste streams from paint, chemical, petrochemical, and
steel manufacturers. A total of 26 different wastes were
obtained from these industrial facilities.
29
-------
TABLE 9. HAZARDOUS POTENTIAL SUMMARY
.a
Coal combustion
Electrostatic precipitators
Wet disposal
Element
Arsenic
Barium
Cadmium
Chloride
Chromium
Copper
Cyanide
Fluoride
Iron
Lead
Manganese
Nitrate
Selenium
Silver
Sulfate
Zinc
Bottom
ash
liquid
Ob
-
-
-
-
-
-
H
X(A)d
-
X(7)e
-
0
-
-
Fly
ash
liquid
0
-
0
-
0
0
-
-
X(700)
0
X(6)
-
X(12)
-
0
Combined
liquid
XC(3)
-
-
-
-
-
0
-
0
-
-
-
-
-
Dry disposal
Bottom
ash
leachate
0
0
0
0
0
-
0
0
0
-
-
0
-
Fly ash
leachate
X(3200)
X(46)
-
X(75)
X(4)
-
-
-
X(61)
-
-
-
0
Flue
desulfur
Bottom
ash
leachate
0
0
0
0
0
-
0
0
0
0
-
-
gas
ization
Fly ash
leachate
0
0
-
0
0
-
0
-
-
0
-
X(10)
Coal conversion
Fluidized
bed
combustion
leachate
X(5)
-
-
-
-
-
0
X(1.3)
X(218)
0
Coal
gasifi-
cation
ash
leachate
X(64)
X(2.7)
-
0
-
X(2.3)
0
0
0
-
Coal
lique-
faction
char /tar
leachate
X(2)
-
X(47)
X(4)
0
-
From Reference 8.
0 - probable hazardous potential
"X - definite hazardous potential
(A) - taken from FGD bottom ash
"(7) - dilution required for mean value to equal criteria
-------
The proposed EP Is being evaluated to determine:
(a) The reproducibility of the method,
(b) Whether the procedure is sufficiently explicit
for use by nonexperienced personnel,
(c) What effect various extractors have upon the
final leachate data,
(d) Whether the liquid-solid separation scheme
is suitable for the wastes encountered.
The EP extracts were first analyzed for arsenic, lead,
cadmium, barium, and chromium by I CAP emission spectroscopy.
The ICAPS was used to qualitatively survey the concentra-
tions found in the leachates. For more quantitative results,
the extracts were analyzed by flame atomic absorption
spectroscopy. The ICAPS results are presented in
Table 10. Pond 0 at Site A, which is a titanium dioxide
process waste from a waste disposal facility, showed high
concentrations of As, Cd, Cr, and Pb in the leachate.
Other extracts from sulfonation tars (Site A, Pond 10),
pesticide waste (Site C), and the filter cake (Site 6)
had metal concentrations below the ICAPS detection
limits.
It was observed that barium, chromium, and lead had high
concentrations in the EP leachates and these elements
were selected for AAS analysis. The AAS data were used
to calculate the relative standard deviation (RSD) of
replicate extractions and replicate determinations on the
same extract (Tables 11 and 12).
For much of the AAS data, the RSD is not available because
the elemental concentrations were lower than the flame AAS
detection limits. The relative standard deviation is less
than 5 percent for both chromium and lead. However, the
barium results indicate an RSD of less than 17 percent
(Table 12). It appears from Table 11, though, that most
of the barium variability is due to the analytical method.
The quality control data for the extracts spiked with barium
(Table 13) indicate a low spike recovery. This seems to
indicate that the matrix interferes with the barium analysis
and suppresses the signal. Another problem occurred during
the aspiration of the sample into the nitrous oxide flame.
Beads formed on the burner head causing a fluctuation of the
flame, which can lead to variation in the detector signal.
The standard solutions did not show this problem, and it
appears to be a matrix effect. This variability of the
signal would increase the standard deviation of the barium
31
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TABLE 10. 1CAPS SCREENING ANALYSIS OF EP EXTRACTS: APPROXIMATE
ELEMENTAL COMPOSITION OF EXTRACTS FROM SELECTED
WASTE SAMPLES3
Approximate Concentration (mg/1)
Sample (No. of Extracts Analyzed)
Site A, Pond 13, Location 1 (1)
Site A, Pond 0, Location 2 (15)
Site A, Pond P, Location 2 (7)
Site A, Pond 10,
Sulfonation Tars (2)
Site B, Paint Sludge,
Sampled 4-19-79 (3)
Site B, Paint Sludge,
Sampled 6-13-79 (1)
Site C, Pesticide Waste (2)
Site D, Chromate Oxidation Paste
Site D, API Oil-Water Separator (3)
Site E, Electric Furnace
Baghouse Dust (1)
Site E, Blast Furnace Scrubber Filter
Cake (1)
Site E, Lime Sludge from Ammonia
Still (1)
Site E, Mill Scale from Water Treatment
Plant (1)
Site C, Filter Cake, Cl/Hg Process
Stream (1)
Site 1, Chlorine Process Sludge (1)
From Reference 9.
As
1.3
168
0.6
<0.4
0.8
0.6
<0.4
0.8
<0.4
1.6
0.6
1.6
<0.4
<0.4
1.8
Chemical, physical and spectral interferences
Ba
0.2
10.8
14.2
1.08
1.13
18
1.26
0.6
<1.002
0.8
1.3
<0.002
<0.002
<0.002
0.07
were not
Cd Cr
0.5 1
4.2 1400
<0.2 124
<0.02 <0
0.06 7
0.02 4
<0.02 <0
0.6 4
<0.02 3
<0.5 3
<0.02 0
<0.02 2
<0.02 3
<0.02 <0
0
minimized.
Pb
.8 0.5
168
1.2
.02 <0.25
.1 1.2
.1 0.25
.02 <0.25
.5 0.4
.6 <0.25
.5 0.5
.4 7
.3 0.4
.1 <0.25
.02 <0.25
.3 0.9
Results
are corrected for dilution. Data for Ponds 0 and P, Site A, represent
averages from analyses of extracts from replicate samples; in some cases,
extracts had to be diluted to bring values within the linear range of the
instrument.
32
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TABLE 11. AVERAGE RELATIVE STANDARD DEVIATION
FOR AAS ANALYSES OF EP EXTRACTS51
RSD (%)
Analysis
(Sample source: Ponds 0 and P, Site A) Barium Chromium Lead
Differences between replicate
determinations on a given
EP extract
Differences between replicate
extractions on a given sample
of waste
14.9
11.0
1.3
1.8
2.0
3.0
From Reference 9.
TABLE 12. EVALUATION OF EXTRACTION PROCEDURE (EP): AVERAGE
MEANS AND STANDARD DEVIATIONS FOR AAS ANALYSES*1
OF EP EXTRACTS OF WASTES FROM PONDS 0 AND P, SITE A
Barium (mg/1)
Sample
Pond 0
Pond P
extracted
2A
2B
2A
2B
X
1.65
1.34
29.9
27.8
RSDC
s (%)
0.17 10.3
0.05 3.7
4.9 16.4
3.7 13.3
Chromium (mg/1) Lead
X
1040
943
77.6
82.5
S
17
21
2.4
2.0
RSD
(%) X
1.6 45.7
2.2 43.5
3.1 -
2.4
(mg/1)
RSD
S (%)
0.5 1.1
2.0 4.6
aFlame Atomic Absorption analyses performed in triplicate on each of
three aliquots of sample extracts.
bFrom Reference 9.
CRSD - Relative Standard Deviation.
Note: n-3
33
-------
TABLE 13. QUALITY CONTROL DATA: COMPARISON OF BARIUM SPIKE
RECOVERY FROM SELECTED SAMPLES (MATRICES)3
Sample
Site A, Pond P
Site B, Paint Sludge
Site D, Chromate
Oxidation Paste
Site D, API Oil
Separator
Site G, Filter Cake
Sample
cone.
(mg/1)
3.10
1.96
0.44
0.33
0.15
Spike
(mg/1)
2.00
2.00
2.00
2.00
2.00
Spiked
cone.
(mg/1)
4.96
3.98
1.94
2.11
1.84
Spike
Recovery
93
101
76
89
84
RSDb
(Analysis)
11
33
18
33
7
Site I, Chlorine
Process Sludge 0.39 2.00 2.28 94 23
Blank, Filtration
Apparatus 0.10 2.00 2.10 100 1
From Reference 9.
Relative Standard Deviation.
34
-------
analysis. No analytical problems were noticed for the
chromium and lead and the percent recovery of spiked
samples was very good.
One problem observed with the EP extract was the forma-
tion of a precipitate after several days, especially
in leachates that had a high concentration of inorganic
salts and organic matter. Even preserving the extract
with acid at pH<2 did not prevent the precipitate from
forming. During this precipitation process, metal species
could coprecipitate with the solid being formed or they
could adsorb onto the precipitate and be removed from the
leachate. This problem is still being investigated.
7. "Final Report: Evaluation of Solid Waste Extraction Procedures
and Various Hazard Identification Tests," R.M. Burd et al.10
Some of the objectives of this program were to determine the
reproducibility of the EP, indicate problems encountered
during the extractions, and to determine the suitability of
the EP for waste materials. Seven solid waste samples were
collected for the program, including coal-fired power plant
fly ash, basic oxygen furnace (EOF) slag, fluid catalytic
cracker (FCC) catalyst fines, petroleum refinery sludge,
organic chemical production still bottoms, paint and pigment
sludge, and spent grain from beer production. Only the
leachates of the first four of these wastes were subjected
to analysis for metals. The samples were sent to three state
laboratories and six commercial laboratories for extraction
by the EP. After extraction, the leachates were sent to a
single laboratory for metal and organic analyses.
The estimation of EP reproducibility is presented in Table 14.
The overall elemental precision is expressed in terms of
the mean value (X) and standard deviation (o) for the nine
extracts of each waste. For analyses that yielded "less than"
values, the mean was not calculated and no precision is re-
ported. The relative standard error (RSE) at the 95 percent
level is calculated from the equation:
RSE = (reported as % of X).
The analytical error reported in Table 14 is based only on
sample analysis, using paired results for a number of sam-
ples (usually 26) . The net EP reproducibility is calculated
by subtracting the square of the analytical RSE from the
square of the overall RSE and taking the square root of the
result.
The net reproducibility for the EP ranged from ±9.2 percent
for As in refinery sludge extract to ±63 percent for As in
fly ash leachate. In all cases, the correction for the
analytical error accounts for only a small change in the pre
cision of the EP. Unfortunately, since the metal analyses
35
-------
TABLE 14. EP REPRODUCIBILITY'
Sample
Fly ash
BOF Slag
Catalyst
fines
Refinery
sludge
Overall precision
Metal (mean, standard deviation, RSE)
As X = 0.227 ± 0.226, ± 66%
Cd -
Cr X = 0.080 ± 0.032, = 26%
Cu -
Cr -
Pb X = 0.441 ± 0.107, ± 16%
Ni X = 0.134 ± 0.060, ± 30%
As -
Pb
Ni
V -
As X = 0.017 ± 0.006, ± 22%
Cd -
Cr -
Pb -
Net EP
Analytical error reproducibility
(RSE) (RSE)
- 20% ± 63%
NCb
=4.6% ± 26%
NC
- NC
± 11% ± 12%
±7% ± 29%
NC
NC
NC
NC
± 20% ± 9.2%
- NC
NC
- NC
From Reference 10.
NC - Not calculated; "less than" values reported for some of the leachates.
-------
were done using flame atomic absorption (as specified in the
EP) more data on the precision of the EP were not obtained
because the concentrations were below the flame AAS detection
limits. For example, arsenic, lead, and vanadium could not
be quantitated for the leachate of catalyst fines.
37
-------
SECTION 6
EXPERIMENTAL
Details of the four leachate generation procedures and the analyses of
the metals and anions are provided below.
EPA-OSW EXTRACTION PROCEDURE
The extraction procedure is described in 43 FR 58956-58957.
Apparatus
The extractor used in the procedure is a stainless steel extractor and
is ba.sed upon the diagram in 43 FR 58961, which is reproduced in Figure 1.
Stirring was accomplished by a high torque stirrer purchased from the Fisher
Scientific Company.
An Orion Research Model 701A pH meter, equipped with a combination glass
electrode, was used to manually monitor the pH.
Procedure
A representative sample (minimum size 100 grams) is separated into solid
and liquid phases by either the filtration or centrifugation method outlined
in the Federal Register. None of the solid wastes examined for this project
existed as two phases, and further separation was unnecessary. The minimum
size of 100 grams was used for the EP.
The solid portion must pass through a 9.5 mm (3/8 inch) standard sieve.
If the particle is too large, the material must be ground or subjected to the
structural integrity procedure. For the energy wastes studied, the particle
.size was small enough to allow passage through a 9.5 mm sieve without grinding
or subjection to the structural integrity test.
An amount of distilled, deionized water equal to 16 times the weight of
solid was added to the waste.
The extraction mixture was stirred at 60 to 65 rpm and the pH maintained
at 5.0 ' 0.2 through the manual addition of 0.5N acetic acid. The pH of the
solution is adjusted at 15-, 30-, and 60-minute intervals, moving to the next
longer Interval if the pH did not have to be adjusted more than 0.5 pH units.
The pH adjustment is to be continued for at least 6 hours. A maximum addition
of 4 ml of acid per gram of solid is allowed during the extraction. If the
38
-------
NON CLOGGING SUPPORT BUSHING
1 Inch BLADE AT 30* TO HORIZONTAL
Figure 1. EP Extractor.
39
-------
maximum amount of acid is added, the 24-hour extraction is completed without
adding any additional acid. The temperature is maintained at 20 to 40°C during
the extraction.
After 24 hours, the mixture is separated into two phases using the filtra-
tion or centrifugation methods indicated above. In this project, the extract
was vacuum-filtered through a 0.45 vim Millipore filter (Type HAWP 047). The
volume of the filtrate was adjusted with distilled, deionized water to 20 times
the initial weight of the solid waste. Since 100 grams of material was ex-
tracted, the final volume was 2 liters.
Enough liquid was removed to completely fill an 8-ounce Nalgene LPE bot-
tle ( 275 ml) and the aliquot was refrigerated for analysis by ion chromatog-
raphy. An equivalent volume was removed, acidified to pH 2 with 1:1 Ultrex
nitric acid, and stored in an 8-ounce Nalgene LPE bottle for atomic absorption
analysis. The remainder of the extract was stored and refrigerated in a
1-liter Nalgene LPE bottle.
ASTM-A METHOD (WATER EXTRACTION)
This water extraction procedure is currently proposed by the American
Society for Testing and Materials as a method for leaching waste materials.
The proposed method follows.
Apparatus
Agitation Equipment
An Eberbach Variable-Speed Reciprocating Shaker capable of operating at
60 to 250 1-inch cycles per minute was utilized for generating the leachates.
Most of the wastes were agitated at 60 cycles per minute, although a shaking
rate of 120 cycles per minute was also used on some samples for comparison
of the data.
Filtration
A Millipore 0.45 ym (47 mm) membrane filter supported on a fritted glass
filter separated the extract from the solid waste.
Conta iners
Round, wide-mouthed, 2-liter Nalgene LPE bottles with screw tops were used
for the extraction. Samples were stored in 8-ounce LPE bottles.
Fifty grams of solid material was dried at 104 ± 2°C for 18 ± 2 hours to
determine the percentage of moisture in the sample. If necessary, the drying
was repeated until a constant weight was achieved.
A representative sample of waste (350.0 grams) was weighed to the nearest
tenth of a gram in a 2-liter LPE bottle.
40
-------
Distilled, deionized water was boiled and cooled to maintain an approxi-
mate starting pH of 6.0 (ASTM Type IV water). The quantity of water added
(1400 ml) is equal to four times the weight in grams of the sample.
The container was closed and agitated continuously for 48 ± 0.5 hours
at 20 ± 2°C. The samples were shaken at the rate indicated above.
After 48 hours, the aqueous phase was separated by filtering through a
0.45 urn Millipore membrane filter.
An 8-ounce LPE bottle was completely filled with the filtrate (~ 275 ml)
and refrigerated for future 1C analysis. Another portion of the extract was
acidified to pH 2 with 1:1 Ultrex nitric acid for AAS analysis and added to
an 8-ounce LPE bottle to completely fill it. The remainder of the aqueous
solution was stored in a 1-liter LPE bottle and refrigerated.
ASTM-B METHOD (ACETATE BUFFER EXTRACTION)
This method is also being investigated by ASTM as a procedure for the
toxic waste program. This method is proposed as an acid complement to the
ASTM water extraction.
Apparatus
The equipment used for the ASTM-B procedure is identical to that described
for the ASTM-A Method.
Procedure
Fifty grams of material was dried as outlined previously in the ASTM
water extraction. The percentage of moisture in the sample is reported.
A representative sample of the waste (350.0 grams) was weighed to the
nearest tenth of a gram and placed in a 2-liter LPE bottle.
An acetic acid-acetate buffer was prepared by dissolving 14.7 grams of
glacial acetic acid and 11.1 grams of sodium acetate in 3 liters of distilled,
deionized water. The pH of the buffer solution was adjusted to 4.5 ± 0.1, with
the dropwise addition of acetic acid (1 M) or sodium hydroxide (1 M), as
required.
The container was closed tightly and shaken at 60 1-inch cycles per
minute for 48 t 0.5 hours.
After 48 hours, the liquid phase was separated from the solid by filtering
through a 0.45 pm Millipore membrane filter.
The aliquots for 1C and AAS analyses were removed and treated in the
manner described above for the ASTM-A Method.
41
-------
CARBONIC ACID EXTRACTION
This extraction was examined as an alternative to the methods using acidic
media.
Apparatus
The equipment is the same as that used for the other shaking tests (ASTM-A
and ASTM-B Methods).
Procedure
A 100.0 gram portion of the sample was weighed and placed in a 2-liter
LPE bottle.
Distilled, deionized water was saturated with gaseous C02 via a gaseous
dispersion tube. A saturation period of 1 hour was required to achieve a
minimum pH of 3.9 to 4.0. A 16:1 liquid-to-solid ratio was employed for the
extraction and 1600 ml of COa-saturated water was added to the waste sample.
Aftfr adding the carbonic acid solution, the bottle was closed tightly
and agitated as in the ASTM extractions for 48 ± 0.5 hours.
A 0.45 ym Millipore membrane filter separated the solid and liquid phases.
Allquots for 1C and AAS analyses were removed as described previously for
the ASTM water extraction.
ATOMIC ABSORPTION
The atomic absorption analyses were done on a Perkin-Elmer Model 460
Spectrophotometer, equipped with deuterium arc background correction. Calibra-
tion curves were used to quantitate the data and determine the linear working
ranges for the metals. The standard solutions were prepared in the matrix
appropriate for each method. Distilled, deionized water was used in the
standard solutions for the CAE Method.
A]1 metals except Ca and Hg were analyzed by the flameless AAS technique
with a Perkin-Elmer HGA-2100 Graphite Furnace. The drying, charring, and
atomization cycles were optimized for each element and each matrix. Data for
the standard solutions and leachate samples were recorded in the peak height
mode of the instrument. Aliquot volumes of 50 or 25 pi were pipetted into
the furnace with an Eppendorf pipet. For the analyses of As and Se, the solu-
tions contained 1000 ppm Ni (as Ni(N03)2) to minimize matrix or chemical
interferences.
Since the concentration of Ca was found to be in the ppm range, Ca was
analyzed in a nitrous oxide-acetylene flame, with the results recorded in the
absorption mode. The ionization interferences present with the nitrous
oxide-acetylene flame were controlled by the addition of a 2000 ppm potassium
solution.
42
-------
Mercury was analyzed using the cold vapor AAS technique. Mercury species
are reduced in acidic solution with stannous chloride. The elemental mercury
formed is swept through a quartz cell with nitrogen where its absorption is
monitored at 253.7 nm.
For quality control purposes, EPA trace metal samples were analyzed.
Some leachates for each matrix were also analyzed by the method of standard
additions to ensure that no matrix interferences existed.
ION CHROMATOGRAPHY
The anionlc analyses of the leachatets were accomplished with a Dionex
Model 14 Ion Chromatograph. The column system employed a 3 x 150 ram anion
pre-column, a 3 x 250 mm anion separator column with the resin in the HCOa
form, and a 6 x 250 mm anion suppressor column with the resin in the H form.
For the F~, Cl", and SOfT determinations, a 0.003 M NaHC03/0.0024 M Na2C03
solution was used as the eluent at a 30 percent flow rate. A 1 N HzSOi* rolu-
tion regenerated the suppressor column after an 8-hour period. The injection
loop had a volume of 100 yl and the sample was introduced from a 5 ml disposable
syringe fitted with a Millipore filter to remove particulate matter.
SPARK SOURCE MASS SPECTROGRAPHY
Spark Source Mass Spectrography (SSMS) was used to perform a semiquanti-
tative elemental survey analysis on the EP leachate of bituminous coal fly ash.
The analysis was performed with a JEOL Analytical Instruments, Inc., Model
JMS-01BM-2 Mass Spectrograph. The instrument is a high resolution, double
focusing mass spectrometer with Mattauch-Herzog ion optics and ion sensitive
photoplate detection.
The electrodes were prepared as follows:
Sample aliquots (20 ml) were placed in vycor dishes and mixed
with an internal standard (7.027 vg of In), approximately 200 rag
of graphite, and 2 ml of distilled, deionized water.
This mixture was slurried and dried under an infrared lamp.
After repeating the slurrying process, the dried mixtures were
placed in agate containers and further homogenized with a Spex
mixer mill for 30 minutes.
The homogeneous mixtures were then packed into polyethylene
slugs and pressed into electrodes under 10 to 11 ton/in2
pressure.
For analysis, the sample electrodes were mounted in the ion source of the
mass spectrometer where they were "sparked" by a high voltage discharge which
decomposed and ionized the electrode mixture. The positively charged ions were
accelerated and the ion beam formed was energy focused and momentum dispersed
for collection on an ion sensitive photoplate. Instrumental parameters are
listed below:
43
-------
Pulse Repetition Rate (Hz) 1000
Pulse Length (microsec) 40
Magnet Current (A) 4.00
Accelerating Voltage (kV) 28.4
Analyzer Pressure (torr) 4 x 10~9
Source Pressure (torr) ~ 1 x 10~7
44
-------
SECTION 7
RESULTS AND DISCUSSION
GENERAL APPLICABILITY OF THE LEACHATE METHODS
To evaluate the general applicability of the leachate methods, the four
procedures were applied to a variety of energy process wastes, including oil
shale* fluidized-bed combustion waste, bituminous coal fly ash, bituminous
coal boiler slag, lignitic coal scrubber sludge, and hopper ash from a coal-
fired power plant. Except for the hopper ash the samples were supplied by
Engineering-Science as part of an ASTM interlaboratory test program to assess
three extraction procedures, the ASTM-A, ASTM-B, and EP methods.11 The pro-
gram was conducted under the auspices of the American Society for Testing and
Materials (ASTM) Subcommittee, D-19.12 and participating Energy Technology
Centers of the U.S. Department of Energy (DOE). The data available on the
samples are given in Table 15. For some of the samples, a description and
analysis of the coal is included, along with the analysis of the sample itself.
Host of these wastes were essentially dry, since no weight was lost when the
percent moisture was determined for the ASTM methods. The only exception was
the scrubber sludge, which had a weight loss of 28 percent upon drying. For
the wastes tested, no procedural problems were encountered with any of the
leaching methods. All of the samples were extracted in the form in which they
were received. None of the wastes had to be ground or subjected to the struc-
tural integrity test, as prescribed in the EP method.
Since the samples were basically dry solids, the separation schemes of
the leachate methods have not been tested thoroughly. For more complex in-
dustrial wastes, a protocol for liquid-solid separation may not be adequately
addressed by some of the procedures. The EP method uses either filtration or
centrifugation to separate the component phases in the original sample. The
filtration procedure uses a pressurized (75 psi) system with a 0.45 urn mem-
brane filter to separate solid and liquid phases. The filtration is stopped
when no more fluid is removed from the waste. The solid and any material
retained by the filter pads are combined for the extraction. For the EP
centrifugation method, the sample is centrifuged for 30 minutes at 2300 rpm.
The heights of the liquid and solid layers are measured to calculate the
liquid-to-solid ratio. Centrifugation is repeated until the liquid-to-solid
ratio is constant for two consecutive centrifugations. Either separation
technique can accommodate some of the wastes that might be encountered, but
A tnore comprehensive approach, possibly using both filtration and centrifuga-
would make the EP separation scheme more effective.
45
-------
TABLE 15. DESCRIPTION AND ANALYSIS OF WASTE SAMPLES3
Sample; Oil Shale
Source: The sample was collected 1 February 1979 from the DOE's
Laramie Energy Technology Center, research retort site, having
been shipped there over the past two years.
General Description:
QS-1; Retorted (spent) oil shale from Green River Formation near
Rifle, Colorado, Run No. 16; ground to pass through No. 8
mesh screen.
Analysis:
Total Mineral Organic Oil Yield
Carbon Carbon Carbon Nitrogen Sulfur gal/ton
OS^-l: 8.86% 5.08% 3.77% 0.18% 0.45% 23.6%
2. SampJLe: Fluidized-Bed Combustion (FBC) Waste
Source: FBC is from the Pope, Evans, and Robbins pilot FBC boiler in
Alexandria, Virginia. The sample was obtained April 1978,
directly from the boiler and stored in sealed containers at
Valley Forge Laboratories in Devon, Pennsylvania.
Approximate analysis of coal used for FBC (Western PA, Sewickley):
Carbon - 72% Loss on Ignition - 87.8%
Sulfur - 3.8% Ash - 12.2%
Chemical and physical analysis of FBC by sample source:
Loss on Ignition - 7.59% CaO - 47.19%
Si02 - 15.34% MgO - 1.00%
Combined Fe & Al oxides - 7.95% SO^ - 19.80%
Specific gravity - 2.76%
Chemical analysis of FBC by receiving lab:
Combined Fe and Al oxides - 1.16%
CaO - 50.23%
MgO - 0.24%
(continued)
46
-------
TABLE 15 (continued)
Bituminous Coal Fly Ash No. 1
The sample was obtained from the Keystone Station of Pennsyl-
vania Electric Company, near Indiana, Pennsylvania. Date of
sampling is unknown. Sample was provided by L. John Minnick,
Consultant.
Approximate analysis of coal used for this waste:
Moisture - 3.5%
. . M--, Heat Value - 12,000 Btu/lb
Asn - lb
Chemical and physical analysis of waste by sample source:
Loss on Ignition - 1.40% Si02 - 50.60%
Combined Fe & Al oxides - 40.1% CaO - 2.2%
Moisture - 0.3% MgO - 2.0%
Specific gravity - 2.29% SO 3 - 0.4%
Amount retained on
No. 325 sieve - 23.54%
Chemical analysis of waste by receiving lab:
Combined Fe & Al oxides - 22.74%
CaO - 7.9%
MgO - 3.19%
4. Sample: Bituminous Coal Fly Ash No. 2
Source: The sample was obtained from the Kammer Plant of Ohio Power
Co. , Moundsville, West Virginia, Unit No. 3. Samples were
taken in February 1979 and were provided by John Faber,
National Ash Association.
Approximate analysis of coal used for waste not available.
Chemical and physical analysis of waste by sample source:
No analysis was completed on the samples used in the program.
A representative analysis of the fly ash is as follows:
Si02
A1203
Fe203
- 35.5%
- 19.4%
- 21.6%
Ti02
Calcium
Magnesium
(continued)
47
- 0.7%
- 3.1%
- 0.6%
-------
TABLE 15 (continued)
Na?0
K20
SO 3
Carbon
- 0.8%
- 1.7%
- 4.1%
- 9.0%
Water loss at 110°C -
Net ignition loss
pH of 1% slurry
after 1 hour
@ 24.5°C
0.8%
2.0%
4.31
Giemical analysis of waste by receiving lab:
A1203 - 18.42% CaO - 1.75% Na20 - 1.08%
Fe203 - 27.69% MgO - 0.97% K20 - 1.20%
Ti02 - 1.07%
5. Sample: Bituminous Coal Boiler Slag
Source: The Ohio Power's Rammer Plant, as referenced for sample 4.
Approximate analysis of coal used for waste:
Moisture - 5.46% Fixed carbon - 45.41%
Ash - 14.47% Sulfur - 4.09%
Volatile matter - 34.66%
Chemical and physical analysis of waste by sample source not available.
Chemical analysis of waste by receiving lab cannot be compared to sample
source results.
6. Sample: Lignite Scrubber Sludge
Source: Sample obtained from Unit No. 2 of the Milton Young Power
Station (430 MW) of the Minnkota Power Cooperative, Center,
North Dakota. The sample was collected on 28 February 1979,
and was taken directly from the vacuum filter. The sample
was provided by Oscar Manz, Coal By-Products Utilization
Institute.
Approximate analysis of coal used for waste:
Moisture - 37.1% Fixed carbon - 25.5%
Ash - 9.74% Sulfur - 0.64%
Volatiles - 27.66% Btu/lb - 6,422
(continued)
48
-------
TABLE 15 (continued)
Chemical and physical analysis of waste by sample source:
SOI+ - 26.83%
S02 -<0.02%
Water content - 42.38%
pH - 4.86
Chemical analysis of waste by receiving lab:
- 6.00%
- 1.66%
The sample was collected 14 February 1979 at Southwestern
Public Services Harrington Station, Unit No. 2 in Amarillo,
Texas.
Analyses of coal used for this waste:
Moisture - 28.04%
Volatiles - 32.81%
Fixed carbon - 33.64%
Chemical analysis of Hopper Ash by
A1203 - 13.3%
CaO - 22.9%
Fe203 - 6.4%
K20 - 0.37%
Ash
Sulfur
Btu/lb
GCA Laboratories:
MgO
Si02
Ti02
- 5.51%
- 0.31%
- 8594
- 3.75%
- 20.5%
- 1.3%
aFrom Reference 11.
^Only the parameters corresponding to sample source analyses appear here.
This will be true for all samples described.
49
-------
The ASTM methods pay little attention to the separation of solid and
liquid components in the waste. No mention is made of a preliminary separa-
tion step prior to the leaching test. For both the EP and ASTM methods, a
widely applicable solid-liquid separation scheme should be included in the
leachate test.
LEACHING CHARACTERISTICS
The results of the leachate tests are presented in Appendix A. The con-
centrations of the species in solution are given in ug per liter except for
Ca, F~, Cl~, and SO^ . The final pH of the leachate is given along with the
volume of 0.5 N acetic acid added during the EP procedure. The final pH data
are also collected and summarized in Table 16. Unless otherwise noted in
Appendix A, the leachates generated by the ASTM-A, ASTM-B, or CAE methods were
agitated at 60 1-inch cycles/minute.
TABLE 16. SUMMARY OF FINAL pH FOR WASTES TESTED3
Waste sample ASTM-A ASTM-B EP CAE
Oil shale
FBC waste
Bituminous coal
Fly ash No. 1
9.
11.
10.
10.
12.
12.
10.
88U
13b
74C
74C
52
54
4
5
5
11
4
.09
.32
.94
.5
8.
8.
12.
12.
5.
5.
5.
70
50
28
32
0
0
0
6.
6.
11.
64
58
74
Bituminous coal 3'28,i 3'11!i
Fly ash No. 2 3.51 3.08d
Bituminous coal 3.55 4.27 4.22d
Boiler slag
Lignitic coal 5.0 4.5 5.1 5.43
Scrubber sludge
Hopper ash 12.13 11.03 9.44 7.30
12.16 11.04 10.37 7.25
12.16 11.02 10.22 7.33
Extraction blank 6.72 4.5 4.7 4.08
unless otherwise noted, the agitation rate for
ASTM-A, ASTM-B and CAE was 60 cycles/minute.
Sample leached with bottle lying horizontally on
shaker.
Sample leached with no agitation.
Agitated at 120 cycles/minute.
50
-------
Fly ash has been shown to affect the pH of the aquatic environment.12
The change in pH, which may be either acidic or basic, is a function of iron
and/or calcium in the fly ash. The amorphous iron oxides produce an acidic
solution while the lime (Ca(OH>2) yields a basic extract in distilled water.
For many of the wastes, the pH of the H20 extraction correlates with the pre-
dominance of Ca or Fe oxide (Table 16). An exception to this is the bituminous
coal fly ash No. 1, which gave a basic pH in distilled water although the major
oxide was iron. For the FBC waste and hopper ash, the predominance of the CaO
offset the acidic media of the ASTM-B, EP, and CAE leachates and produced a
final basic pH.
The release of trace metals has been correlated with the pH of the aque-
ous extract.12 The desorption of trace metals from fly ash surfaces decreases
with increasing pH. The extent of trace metal solubilization is determined
largely by the degree of solubilization of the surface oxide associated with
the trace metal. Therefore, a surface analysis of the wastes may be necessary
to interpret the solubility trends of the four leachate tests. Arsenic was
unique in its increased release at pH 12. If arsenic is present as an anion,
as AsOif3", it could form insoluble compounds at lower pH values (e.g., FeAsOjj,
v m 1.8 * 1CT20). With an increase in pH, the free metal ions would be pre-
cipitated as hydroxides and the arsenic concentration would increase.
Some of the initial metals analyses were done by flame atomic absorption.
This applies to the results for the bituminous coal fly ash No. 1 and the
lignite coal scrubber sludge. Since many of the results for these leachates
were below the flame AAS detection limits, it was necessary to use the graphite
furnace, with its greater sensitivity, for the AAS analyses. Those metals,
including all calcium data, analyzed by flame AAS are indicated in the tables
in Appendix A. Arsenic and selenium were determined only by graphite furnace
methods, and mercury was analyzed using the cold vapor technique. The detec-
tion limits for the AAS and 1C analyses are given in Table 17.
AAS analyses were done on the leachates preserved for metals (i.e., pH
adjusted to <2 with Ultrex nitric acid) and on the reserved (unpreserved)
portion of the extract. Since the preservation methods for the leachates are
either not defined (as in the EP) or poorly defined (as in the ASTM methods),
the reserve portion of some of the leachates was analyzed to determine the
effect upon the AAS results. For most of the metals, there is little differ-
ence between analyses of the preserved and unpreserved leachates. However,
the time lapse between extraction and analysis may not have been sufficient
to cause a loss of metals from the reserve solution. It is certainly advis-
able to preserve the extracts for subsequent analyses, and proper preservation
methods should be explicitly defined in any standard leaching test.
The metal concentrations in the leachates, which exceeded the RCRA
threshold levels, are indicated in the data tables in Appendix A. Based on
the RCRA criteria, five of the energy wastes would be classified as hazardous
by at least one of the leachate methods and the findings are summarized in
51
-------
Table 18. The hazardous leachates were extracts of oil shale, bituminous
coal fly aah, scrubber sludge, and hopper ash. Hazardous leachates for the
scrubber sludge and hopper ash were produced by all four methods. In most
cases, the concentration of selenium exceeded the maximum acceptable concen-
tration of 10 times the National Interim Primary Drinking Water Standards
(0.1 mg/1 for Se). In the interlaboratory program conducted by Engineering-
Science, selenium levels were often in excess of proposed EPA limits.11
Arsenic, cadmium, chromium, and lead also exceeded the concentration limits
in some of the leachates.
TABLE 17. DETECTION LIMITS FOR ATOMIC ABSORPTION
AND ION CHROMATOGRAPHIC ANALYSES
Detection limits for atomic absorption
Metal
Ag
As
Ba
Ca
Cd
"Cr
Pb
Se
Hg
Flame (ppm)
0.06
0.4
0.08
0.025
0.10
0.5
1.0 ppb by
Graphite furnace (ppb)
0.5
1.0
1.0
0.1
1.0
1.0
5.0
cold vapor method
Detection limits for ion chromatography
Anion 1C (ppm)
F" 0.1
Cl" 0.1
0.2
Four toxic leachates were produced by each of the ASTM methods, while
the KP and CAE methods each yielded three hazardous extracts. Presumably,
the larger quantity of solid waste leached in the ASTM methods (350 grams
verwus 100 grams) coupled with the lower liquid-to-solid ratio employed by
the ASTM procedures yields leachates with high trace metal concentrations.
This would also imply that common ion effects are not a problem at this 4:1
liquid-to-solid ratio and did not limit the concentrations of some of the
inorganic contaminants. The higher solution concentrations and the number
of toxic extracts produced by the ASTM methods also emphasizes the subjectiv-
ity involved in deciding upon a single leachate test to determine the hazards
of waste disposal. For example, it is conceivable that some metals would be
52
-------
TABLE 18. WASTES CLASSIFIED AS TOXIC BY RCRA CRITERIA
Waste
Oil shale
Fluldized-bed
combustion waste
Bituminous coal
fly ash No. 1
Bituminous coal
fly ash No. 2
Bituminous coal
boiler slag
Lignitic coal
scrubber sludge
Hopper ash
Procedure
ASTM-A
ASTM-B
EP
CAE
ASTM-A
ASTM-B
EP
CAE
ASTM-A
ASTM-B
EP
CAE
ASTM-A
ASTM-B
EP
CAE
ASTM-A
ASTM-B
EP
CAE
ASTM-A
ASTM-B
EP
CAE
ASTM-A
ASTM-B
EP
CAE
Element (s) exceeding
threshold value
Se
Nonea
None
None
None
None
None
None
Se
As, Se
As, Se
NRb
NR
As, Cr, Se
NR
As, Cr
None
None
NR
None
Se
Se
Se
Se
Se
Cr, Se
Se
Se
wone no elements exceeded the threshold value.
NR not run.
53
-------
leached to a greater extent (on a Mg/g basis) in the EP or CAE methods, but
the higher liquid-to-solid ratio could lower the concentration below the
threshold level. Thus, the leachate would not be classified as hazardous
and disposal of the waste would not be considered an environmental problem.
To avoid this dependence upon the liquid-to-solid ratio, the criteria could
be based on the micrograms of metal extracted per gram of waste.
To illustrate this point, the concentration data in Appendix A have been
converted to the mass of species extracted per gram of dry sample. The gen-
eral equation used to calculate the data in Tables 19 through 27 can be ex-
pressed as:
leachate concentration
leachate volume (1) _ yg
weight of dry sample (g) g
For all wastes except the scrubber sludge, the weight of sample used in the
leachate procedure was the same as the dry sample weight (either 350 or 100
grams). The scrubber sludge lost 28 percent of its weight upon drying and
the dry sample weight was adjusted accordingly. The trace metals are expressed
in ug/g, while calcium and the anions are reported as mg/g. The weight/weight
data facilitates intermethod comparisons.
TABLE 19. COMPARISON OF LEACHATE DATA (IN yg/g)3 FOR OIL SHALE
Species
Ca (mg/g)
Ag
As
Ba
Cd
Cr
Hg
Pb
Se
F~ (mg/g)
Cl~ (mg/g)
SO,,2' (mg/g)
ASTM-A
0
<0
0
<1
<0
0
<0
0
0
0
0
4
.88
.004
.44
.6
.0004
.019
.004
.064
.17
.016
.009
.9
4
<0
0
0
0
0
<0
<0
<0
1
ASTM-B
.8
.002
.26
.14
.088
.12
.004
.004
.02
c
c
.6
6
<0
0
0
0
0
<0
<0
<0
2
b
.4
.002
.23
.12
.092
.072
.004
.004
.02
c
c
.0
EPb
22
<0.01
0.24
2.8
<0.002
0.28
<0.02
0.64
<0.1
c
c
12.6
CAEb
22
<0.01
0.32
6.8
0.006
0.19
0.02
0.30
0.26
c
c
9.4
2.
0.
1.
4.
0.
0.
<0.
0.
1.
0.
0.
12.
7
010
4
0
006
022
016
11
1
08
034
5
2.9
0.010
1.3
4.3
0.003
<0.016
<0.016
0.091
1.0
0.075
0.034
14.6
Unless otherwise indicated, concentration given in pg/g of dry waste.
Leached in duplicate.
°Acetate interference.
54
-------
TABLE 20. COMAPRISON OF LEACHATE DATA (IN yg/g)a
FOR FBC WASTE
Species
Ca (mg/g)
Ag
As
Ba
Cd
Cr
Hg
Pb
Se
F~ (mg/g)
Cl" (mg/g)
S0it2~ (mg/g)
ASTM-Ab
3.8
<0.002
0.15
<1.6
0.002
0.25
<0.004
0.036
0.16
0.005
0.02
3.8
4
<0.002
0.14
<1.6
0.002
0.12
<0.004
0.048
0.16
0.005
0.03
4.9
ASTM-B
10.8
<0.002
0.25
0.22
0.068
0.44
<0.004
<0.004
<0.02
c
c
2.0
EPb
5J6
<0.01
0.17
7.2
0.004
0.24
<0.02
0.16
0.24
c
c
17
56
<0.01
0.13
7.6
0:018
0.30
0.02
0.21
0.24
c
c
25.6
CAE
4.3 "
0.010
0.40
1.1
<0.002
0.27
<0.016
0.093
0.45
0.010
0.048
2.6
*Unless otherwise indicated, concentration given in yg/g of
dry waste.
Leached in duplicate.
Acetate interference.
TABLE 21. COMPARISON OF LEACHATE DATA (IN v»g/g)a
FOR BITUMINOUS COAL FLY ASH NO. 1
Species
Ca
Ag
As
Ba
Cd
Cr
Hg
Pb
.Se
F"
Cl"
sog
(mg/g)
(mg/g)
(mg/g)
" (mg/g)
ASTM-A
0.76
<0.24
1.5
<1. 6
<0.1
<0.4
<0.004
<2.0
0.64
<0.004.
<0.004
1.0
ASTM-B
1.1
<0.24
9.7
<1.6
<0.1
1.2
<0.004
<2.0
0.56
c
c
1.2
2.2
<1.2
22.4
<8.0
<0.5
<2.0
<0.02
<10
2.2
c
c
3.6
EPb
3.2
<1.2
28.8
<8.0
<0.5
<2.0
<0.02
<10
2.8
c
c
4.0
3.2
<1.2
36.6
<8.0
<0.5
<2.0
<0.02
<10
0.9
c
c
4.2
"unless otherwise indicated, concentration given
in yg/g of dry waste.
Leached in triplicate.
cAcetate interference.
55
-------
TABLE 22. COMPARISON OF LEACHATE DATA
(IN ug/g)a FOR BITUMINOUS
COAL BOILER SLAG
TABLE 23. COMPARISON OF LEACHATE DATA
(EJ ug/g)a FOR LIGNITIC COAL
SCRUBBER SLUDGE
Species
Ca (ing/g)
Ag
As
Ba
Cd
Cr
Hg
Pb
Se
F~ (mg/g)
Cl~ (mg/g)
SO/*2" (mg/g)
ASTM-A
0
<0
<0
<1
<0
<0
<0
<0
<0
<0
<0
0
.006
.002
.004
.6
.0004
.004
.004
.004
.02
.004
.004
.048
ASTM-B
0
<0
0
0
0
0
<0
<0
<0
0
.028
.002
.096
.12
.015
.018
.004
.004
.02
c
c
.13
CAEb
0
<0
<0
0
<0
<0
0
<0
<0
<0
0
0
.010
.008
.016
.19
.002
.016
.019
.016
.08
.016
.024
.066
Species
Ca (mg/g)
Ag
As
Ba
Cd
Cr
Hg
Pb
Se
F~ (mg/g)
Cl~ (mg/g)
S0^2~ (mg/g)
ASTM-A
3.2
<0.33
0.83
<2.2
<0.14
<0.56
<0.006
<2.8
0.67
<0.006
0.012
10.9
ASTM-B
3.9
<0.33
2.0
<2.2
<0.14
<0.56
0.006
<2.8
0.73
b
b
12.6
EP
14.2
<1.7
3.9
<11.1
<0.56
<4.0
<0.03
<14.0
3.1
b
b
36.4
CAE
13.3
0.022
3.6
1.7
0.031
0.027
<0.022
0.031
3.4
0.049
0.087
33.6
unless otherwise indicated, concen-
tration given in Mg/g of dry waste.
Agitated at 120 cycles/minute.
c
Acetate interference.
Unless otherwise indicated, concentration
given in ug/g of dry waste.
Acetate interference.
-------
TABLE 24. COMPARISON OF LEACHATE DATA (IN pg/g) GENERATED
BY THE ASTM-A PROCEDURE FOR HOPPER ASH
Species
Ca (mg/g)
Ag
As
8a
Cd
Cr
HK
Ph
Se
F~ (mg/K)
Cl~ (mg/g)
SO,/~ (mg/g)
First
replicate
1.9
<0.002
0.11
7.5
<0.0004
0.48
<0.004
0.031
1.6
0.038
0.004
0.60
.j ( It
Second
replicate?
2.0
<0.002
0.11
9.0
0.0004
0.48
<0.004
0.032
2.2
0.039
0.004
0.76
Third
replicate
1.7
<0.002
0.10
7.2
<0.0004
0.44
<0.004
0.034
1.9
0.039
0.004
0.80
Muan c
1.9
<0.002
0.11
7.9
<0.0004
0.47
<0.004
0.032
1.9
0.039
0.004
0.72
i . . _ 1
Standard
leviation (n)
0.15
-
0.006
0.96
-
0.023
-
0.0015
0.25
0.00058
0
0.11
ft.
TABLE 25. COMPARISON OF LEACHATE DATA (IN yg/g) GENERATED
BY THE ASTM-B PROCEDURE FOR HOPPER ASH
Species
Ca (mg/g)
Ag
An
Ba
Cd
Cr
Hg
Pb
Se
F~ (mg/g)
Cl" (mg/g)
SO,,*' (mg/g)
First
replicate
9.2
<0.002
0.28
0.48
0.027
2.2
<0.004
<0.004
5.8
b
b
9.8
Second
replicate
8.8
<0.002
0.28
0.52
0.020
2.0
<0.004
<0.004
7.7
b
b
8.4
Third
replicate
8.8
<0.002
0.24
0.52
0.028
2.0
<0.004
<0.004
6.8
b
b
6.9
Mean
8.9
<0.002
0.27
0.51
0.025
2.1
<0.004
<0.004
6.8
-
8.4
Standard
deviation (o)
0.23
-
0.023
0.023
0.004
0.12
-
-
0.95
-
1.45
Unless otherwise Indicated, concentration given in ug/g of dry waste.
Acetate Interference.
57
-------
TABLE 26. COMPARISON OF LEACHATE DATA (IN ug/g) GENERATED
BY THE EXTRACTION PROCEDURE FOR HOPPER ASH
Species
Cn '(mK/g)
Ag
As
11 a
Cd
Cr
»r,
Pb
Se
F (mg/p,)
(-)" (mg/g)
SO,/" (mg/g)
First Second
replicate replicate
44
^0.01
0.30
4.2
0.01
3.8
^0.02
0.26
4.0
b
13.4
' Unless otherwise Indicated
44
<0.01
0.60
3.6
0.002
3.0
<0.02
0.28
3.0
b
b
Third
replicate
44
=0.01
0.34
3.4
0.002
6.6
<0.02
0.34
3.0
b
b
Mean
44
<0.01
0.41
3.7
0.005 '
4.5
<0.02
0.29
3.3
-
9.0 11 11.1
, concentration given in iig/g
Standard
deviation (n)
0
-
0.16
0.42
0.0046
1.9
-
0.042
0.58
-
' 2.2
of dry waste.
Acetate Interference.
TABLE 27. COMPARISON OF LEACHATE DATA (IN yg/g)3 GENERATED
BY THE CARBONIC ACID EXTRACTION FOR HOPPER ASH
Species
Co (mg/g)
AK
Af)
Bn
Cd
Cr
HP,
Pb
S,
V (mfc/g)
C1~ (mg/g)
S(>,,?~ (r.ir./g)
First
replicate
3.0
0.008
1.4
11.4
0.006
2.9
<0.016
0.13
5.6
0.032
0.026
4.0
Second
replicate
3.4
<0.008
1.8
11.4
0.010
3.4
<0.016
0.13
7.5
0.034
0.026
4.5
Third
replicate
3.4
<0.008
1.8
11.2
0.006
3.2
<0.016
0.13
8.0
0.053
0.024
4.8
Mean
3.3
<0.008
1.7
11.3
0.007
3.2
<:0.016
0.13
7.0
0.040
0.025
4.4
Standard
deviation (a)
0.23
-
0.23
0.12
0.002
0.25
-
0
1.3
0.016
0.001
0.40
aUnle«K otherwise indicated, concentration given in Mg/g of dry waste.
58
-------
As indicated in Tables 19 through 27, the major components in the
leachates are calcium and sulfate. The soluble trace metals exist primarily,
then, as sulfates in these energy process wastes. This conclusion is sup-
ported by the findings of a previous study.13 The 1C analyses of aqueous
extractions of oil-fired and coal-fired fly ashes indicated that the pre-
dominant anion in solution was SOi,2'. Fourier transform infrared analysis
of the water-soluble fractions supported the assumption that the soluble
metals nickel, vanadium, and magnesium are sulfate forms. Cations contained
in the insoluble portion of the fly ash were assumed to be oxides. An
investigation of vanadium special:ion in the oil-fired fly ashes revealed
that the water soluble fraction contains V^+OSO^ X H20 with V^Os in the
insoluble portion of the ash.
It is also interesting to note that, regardless of the method used for
extraction, selenium often exceeded the RCRA threshold value. In a study of
the solubility of trace elements in coal fly ash,14 it was determined that
acidic, neutral, and basic solutions could solubilize selenium from fly ash. A
1 M HNOs solution was the most efficient for extracting the selenium, while
the H20 and NHi+OH extracts were comparable in the amounts leached from the
fly ash, but were much lower than the acidic solution. The anionic character
of selenium in the fly ash could account for its partial solubility in the
H20 extraction (ASTM-A method). Selenium is probably present as the selenate
anion (SeOj*2 ) which is leached more readily in H20 than a cationic species
uch as Cd or Cu.
As an aid to evaluating the leachate data, the number of times each
leachate method gave the highest concentration or highest quantity (in mass/g
of dry sample) of an inorganic contaminant is tabulated in Tables 28 and 29,
respectively. The results were compared only for the four wastes extracted
by all four leachate procedures. These four wastes were oil shale, FBC waste,
lignite coal scrubber sludge, and hopper ash. When a waste was extracted
more than once by a method, the results were averaged before comparing the
data. In some cases, the results were below the detection limits of the
analytical technique, and an intercomparison of the leachate tests was not
made. This omission of some data sets is reflected in the number of compar-
isons made for each inorganic species (the maximum number of tests for each
species would be four). No comparisons were made for fluoride and chloride
because these anions could not be analyzed in the leachates generated by the
ASTM-B and EP methods.
It is evident from Table 28 that for most of the inorganic constituents
in the leachates, the ASTM methods gave the highest concentration. The ASTM
methods account for the highest leachate concentration 71 percent of the
time. These results are also reflected in the leachates found to be hazardous.
The ASTM methods produced more toxic leachates than the other two methods.
However, the quantity of metal (or anion) leached per gram of dry solid is
generally higher for the EP and CAEjnethods. These latter methods gave the
largest quantities of metal or SO^2" for many of the wastes extracted. This
indicates that the maximum amount of material, whether trace or major com-
ponent, has not been released from the solid during the leachate generation
by the ASTM methods.
59
-------
TABLE 28. NUMBER OF TIMES EACH LEACHATE TEST GAVE THE HIGHEST
CONCENTRATION OF AN INORGANIC CONTAMINANT. (ONLY
FOR WASTES EXTRACTED BY ALL FOUR LEACHATE METHODS.)
Contaminant
Ca
Ag
As
Ba
Cd
Cr
Hg
Pb
Se
SOU2~
Totals
Percent Of
ASTM-A
1
1
1
1
1
2
7
total comparisons 23
ASTM-B
3
2
3
3
1
1
2
15
48
For some leachates, the concentration is below
comparison
TABLE 29.
Contaminant
Ca
Ag
As
Ba
Cd
Cr
Hg
Pb
Se
S0n2~
Totals
is made.
EP
1
2
2
5
16
the
CAE Total
1
1
2
4
13
comparisons
4
2
4
1
3
3
3
3
4
4
31a
detection limit and no
NUMBER OF TIMES EACH LEACHATE TEST GAVE THE LARGEST QUANTITY
(MASS/g OF SAMPLE) OF AN INORGANIC CONTAMINANT. (ONLY FOR
WASTES EXTRACTED BY ALL FOUR LEACHATE METHODS.)
ASTM-A ASTM-B
0
Percent of total comparisons 0
3
1
4
13
EP
4
1
2
2
2
3
3
17
53
CAE Total
2
3
1
4
1
11
34
comparisons
4
2
4
3
3
3
2
3
4
4
32a
Comparisons are not made when "less than" values are reported for each
leachate method.
60
-------
Based on the results in Table 29, some leachate procedures exhibit an
elemental selectivity. More cadmium is extracted by the ASTM-B method than
by the other procedures. This trend is also observed for the extraction of
selenium, arsenic, and silver by the CAE method. The EP method extracts the
largest quantity of materials, especially the major components, Ca2+ and SOi^2"".
This is probably due to the higher liquid-to-solid ratio and the EP's more
aggressive agitation method. However, more vigorous stirring in the EP could
cause the particles to break up and expose new surfaces to the leaching medium.
The results, then, might be higher for the EP, and unrealistic in predicting
the environmental impact of the waste disposal.
It is difficult to explain some of the elemental selectivity indicated
above. Except for the hopper ash, cadmium is preferentially extracted by the
leachate solution that has the lowest pH. In most cases, this is the leachate
generated by the ASTM-B method. Cadmium, which exists as a cationic species
In fly ash, has been shown to be leached more readily in acidic solutions.14
The concentration of certain elements on the surface of fly ash may also
account for some of the solubility trends. The surface predominance of an
element is probably related to its volatility. The surface predominance of
some trace metals has been studied by numerous instrumental surface techniques,
Including ion microprobe mass spectrometry, secondary ion mass spectrometry,
and Auger electron spectrometry.15 The enrichment of selenium on the surface
of fly ash nas been based on a volatilization-condensation concept.16 In
this concept, the selenium is volatilized during the combustion process and
subsequently condenses or preferentially adsorbs onto small airborne particles
that have a large surface area per unit mass. Thus, selenium may be extracted
to a greater extent by the four leachate procedures than some other elements.
This is evident in Table 18, where the selenium concentration often exceeded
the RCRA criteria.
Arsenic and chromium are also known to concentrate on the surface of fly
ash particulate. The study on trace metal solubility in coal fly ash11* dem-
onstrated that arsenic and chromium could be solubilized in acidic media, but
they were sparingly soluble in H20. This information is reflected in the data
for the fly ash and hopper ash samples. When the quantity of As and Cr
leached by the ASTM-A method is compared with the other three methods, more
As and Cr have been extracted in the acidic solutions. When arsenic and
chromium exceeded the RCRA threshold values, it was only in the fly ash and
hopper ash wastes and only for the leaching tests that used acidic solutions
for extraction (Table 18).
The association of some trace metals with a particular surface oxide has
also been investigated.12 Most of the trace metals are associated with the
iron oxides on the surface of the fly ash, but cadmium and nickel were found
to exhibit a preference for the manganese portion of the fly ash coating.
This preference for surface oxides is expected to influence the release of
trace metals in aqueous solutions.
The association of trace metals with the major oxides is partially
caused by specific interactions at the furnace temperature. It is also sug-
gested that the distribution of trace metals in the fly ash particles is due
61
-------
co its geochcmical association wich the various mineral forms in the coal. For
example, arsonic was associated preferentially with iron on the surface of the
fly ash. Arsenic probably exists in coal as an arsenical pyrite. Since the
sulfidfis of arsenic and iron are volatile, these species could co-condense on
the surface of the cooling particles.
The percentages of metals leached from the energy process wastes have been
calculated in Tables 30 to 35. Except for the hopper ash, the elemental analyses
were done by inductively coupled argon plasma spectrometry (ICAPS) and were sup-
plied by Engineering-Science in conjunction with the ASTM round-robin program to
evaluate leachnte procedures. No ICAPS data were reported for the oil shale.
Analysis of the hopper ash was conducted by the GCA Analytical Laboratory.
After total digestion of the hopper ash, the metals were measured by flame AAS
The results are reported in yg/g, except for Ca which is listed as percent Ca.
No percentage is reported for results that were below the detection limits for
either ICAPS or flameless AAS.
Many of the results indicate that less than 1 percent of the metal was
leached from the waste. Chromium was extracted in a greater percentage than
the othor trace metals. The percentage of chromium extracted is especially
high for the fly ash samples leached by the ASTM-B and CAE methods. This re-
emphaaizes the availability of Cr on the surface of fly ash and its solubility
in acidic media. It appears that most of the other trace metals may be bound
to the sample matrix in a manner that makes them unavailable for leaching.
Another possibility is that the compound forms of the trace metals are not
solubilized by the leaching media.
PRECISION OF LEACHATE METHODS
Another means of evaluating the four leachate procedures is to compare
the precision of replicate extractions. The relative standard error (RSE) was
chosen to indicate the precision of a method and is expressed as a percentage
of the mean. It measures the extent to which a sample mean can be expected
to fluctuate due to chance. The equation used to calculate the RSE incorporates
che number of replicate extractions performed and can be expressed:
RSE (%) = -=£-=: x 100 %
X
where o is the standard deviation, n is the number of replicates, and X is the
mean. The standard deviation (a) is calculated using the equation:
N - 1
62
-------
TABLE 30. PERCENTAGE LEACHED FROM THE FBC WASTE
Metal
Ca
Ag
As
Ba
Cd
Cr
Hg
Pb
Se
Concentration of
*i
metal in waste
35.9%
<150
<600
80
<30
22
<0.0002
<450
<300
ASTM-A ASTM-B EP CAE
1.1 3.0 16 1.2
_ _ _ _
_ _ _ _
0.3 9.3 1.4
0.8 2.0 1.2 1.2
_ _ _ _
_ _ _ _
_ _ _ _
Q
otherwise indicated.
TABLE 31. PERCENTAGE LEACHED FROM THE
BITUMINOUS COAL FLY ASH NO. 1
Metal
Ca
Ag
As
Ba
Cd
Cr
Hg
Pb
Se
Concentration of AgTM_A ASTM_fl
metal in waste3
5.65% 1.3 1.9
178
5157
_ _ _
19 - 6.3
0.0006 - -
594
771 0.1 0.1
EP
4.5
0.3
"T» 1 j _ f -i- /» A T* o ^ _ - i _ _ i _ -.»_ _*- _/_
unless otherwise indicated.
63
-------
TABLE 32. PERCENTAGE LEACHED FROM THE
BITUMINOUS COAL FLY ASH NO. 2
ASTM-B
Metal
Ca
Ag
As
Ba
Cd
Cr
Hg
Pb
Se
Concentration of -
metal in waste3
1.25%
265
482
312
0.0002
954
1193
First
run
19
0.07
0.08
15
0.3
Second
run
18
0.04
0.09
15
0.4
CAEb
51
0.02
0.8
10
0.2
0.04
unless otherwise indicated.
Agitated at 120 cycles/min.
TABLE 33. PERCENTAGE LEACHED FROM THE
BITUMINOUS COAL BOILER SLAG
Metal
Ca
Ag
As
Ba
Cd
Cr
Hg
Pb
Se
Concentration of . b
. , . . a AS1M-A ASTM-B CAE
metal in waste
0.52% 0.1 0.5 0.2
188 -
302 - 0.04 0.06
_ _
175 - 0.01 -
0.0003 - -
629 - - -
958 - -
c
Results of ICAPS analysis given in pg/g
unless otherwise indicated.
Agitated at 120 cycles/min.
64
-------
TABLE 34. PERCENTAGE LEACHED FROM THE
LIGNITE SCRUBBER SLUDGE
Metal
Ca
Ag
As
Ba
Cd
Cr
Hg
Pb
Se
Concentration of
metal in waste3
6.96%
<150
950
4800
70
13
0.0003
<450
<300
ASTM-A ASTM-B EP CAE
4.6 5.6 20 19
_ _ _ _
0.09 0.2 0.4 0.4
- 0.04
- - - 0.04
0.2
_ _ _ _
_ _ _ _
_ _ _ _
rt
Results of ICAPS analysis given in yg/g unless
otherwise indicated.
TABLE 35- PERCENTAGE LEACHED FROM THE
HOPPER ASH
Metal Concentration of ^-l ^_^ ^
metal in waste1*
Ca
Ag
As
Ba
Cd
Cr
Hg
Pb
Se
16.4%
32.9
4800
6.06
134
0.46
97
1.2
0.3
0.2
0.4
0.03
5.4
0.8
0.01
0.4
1.6
27
1.2
0.08
0.08
3.4
0.3
2.0
5.2
0.2
0.1
2.4
0.1
Tlesults of AAS analysis given in pg/g unless
otherwise indicated.
-------
Tin; relative standard error has been calculated for the replicate extrac-
tions of aome wastes and is presented in Tables 36 to 40. If the RSE is com-
pared for the hopper ash leachates (Table 36), the precision for the ASTM methods
in comparable, with the ASTM-A method having slightly better reproducibility.
The Carbonic Acid Extraction (CAE) is a close third in precision behind the
ASTM methods. The Extraction Procedure had the worst reproducibility for the
hopper ash extractions. A comparison of the precision for other wastes also
indicated that the RSE for the EP was below that of the other methods.
Differences in the chemical composition of the waste samples may account for
some of the irreproducibility of the four extraction procedures. However, the
precision of the EP was always below that of the other methods for the wastes
tested.
The precision of the methods tested in this study can be compared with
results of previous investigators. One study found that the intralaboratory
reproducibility for the EP was quite good with chromium and lead having relative
standard deviations of less than 5 percent.9 Another investigation into the
inter laboratory precision of the EP demonstrated that the relative standard
error ranged from ' 9.2 percent for As in refinery sludge extract to t 63 percent
for As in fly ash leachate.10 Eighteen laboratories participated in the round-
robin program conducted by Engineering-Science and the leachate results show
extreme variability for the three procedures tested (i.e., ASTM-A, ASTM-B, and
EP).1' Ono conclusion drawn from the data was that the precision exhibited no
consistent difference between the extraction methods.
A comprehensive study was undertaken by the Electric Power Research
Institute (EPRI) to evaluate the reproducibility of the proposed RCRA Extraction
Procedure.'J An analytical scheme was devised to address the following sources
of variability:
1. Interlaboratory extraction variability.
2. Intralaboratory extraction variability.
3. Interlaboratory analysis variability.
4. Intralaboratory analysis variability.
5. Unallocated variability observed variability cannot
be attributed to any of the previous causes of variation.
Since the results presented in this report represent intralaboratory extrac-
tion and analysis, the intralaboratory variabilities cited in the EPRI study are
highlighted. For the wastes tested and all metals except chromium, only a
small portion of the variability (usually less than 10 percent) was attributed
to intralaboratory extraction variability. The intralaboratory extraction vari-
ability was more than 20 percent for chromium. The intralaboratory analysis
variability contributed a significant portion to the variation of the flameless
AAS analyses for lead and selenium.
66
-------
TABLE 36. CALCULATION OF RELATIVE STANDARD ERRORa FROM RESULTS OF HOPPER ASH EXTRACTIONS
Ca
Ag
As
Ba
Cd
Cr
Hg
Pb
Se
F~
Cl~
SOit2"
X
1.9
<0.002
0.11
7.9
<0.0004
0.47
<0.004
0.032
1.9
0.039
0.004
0.72
ASTM-A
a
0.15
0.006
0.96
0.023
0.0015
0.25
0.00058
0
0.11
ASTM-B
n
3
3
3
3
3
3
3
3
3
3
3
3
RSE
(%)
4.6
3.2
6.9
2.8
2.7
7.5
0.9
0
8.7
X
8.9
<0.002
0.27
0.51
0.025
2.1
<0.004
<0.004
6.8
b
b
8.4
a
0.23
0.023
0.023
0.004
0.12
0.95
1.45
n
3
3
3
3
3
3
3
3
3
3
3
3
RSE
(%)
1.5
4.9
2.6
9.2
3.3
8.1
9.8
X
44
<0.01
0.41
3.7
0.005
4.5
<0.02
0.29
3.3
b
b
11.1
EP
a
0
0.16
0.42
0.0046
1.9
0.042
0.58
2.2
n
3
3
3
3
3
3
3
3
3
3
3
3
RSE
U)
0
23
6.4
53
24
8.1
10
12
X
3.3
<0.008
1.7
11.3
0.007
3.2
<0.016
0.13
7.0
0.04
0.025
4.4
CAE
a
0.23
0.23
0.12
0.002
0.25
0
1.3
0.016
0.001
0.40
n
3
3
3
3
3
3
3
3
3
3
3
3
RSE
(%)
4.0
8.1
0.64
17
4.5
0
11
23
2.3
5.3
Relative Standard Error (RSE)
(expressed as % of X)
where a = standard deviation
X = mean
n - number of replicate extractions
,Art
" 10° Percent
Acetate interference.
-------
TABLE 37. CALCULATION OF RELATIVE STANDARD ERROR (RSE)a ₯OR EACH LEACHATE
GENERATED BY THE ASTM-A METHOD
00
Oil shaleb
Ca
Ag
As
Ba
Cd
Cr
Hg
Pb
Se
F"
Cl~
SOi+2~
X
0.46
0.0055
0.52
0.41
0.002
0.025
<0.004
0.052
0.84
0.012
0.013
6.9
a
0.085
0.0007
0.057
0.014
0
0.005
0
0
0
0.004
1.4
n
2
2
2
2
2
2
2
2
2
2
2
2
RSE
(%)
13
9.0
7.8
2.4
0
14
0
0
0
22
14
X
3.9
<0.002
0.15
<1.6
0.002
0.19
<0.004
0.042
0.16
0.005
0.025
4.4
FBC
a
0.14
0.007
0
0.092
-^
0.0085
0
0
0.007
0.78
Hopper ash
n
2
2
2
2
2
2
2
2
2
2
2
2
RSE
(%)
2.5
3.3
0
34
-
14
0
0
20
13
X
1.9
<0.002
0.11
7,9
<0.0004
0.47
<0.004
0.032
1.9
0.039
0.004
0.72
0
0.15
0.006
0.96
0.023
0.0015
0.25
0.00058
0
0.11
n
3
3
3
3
3
3
3
3
3
3
3
3
RSE
(%)
4.6
3.2
6.9
2.8
2.7
7.5
0.9
0
8.7
RSE = r~^ * 100 percent.
Leachate generated without agitation.
-------
TABLE 38. CALCULATION OF RELATIVE STANDARD ERROR
(RSE)a FOR EACH LEACHATE GENERATED BY
THE ASTM-B METHOD
Oil shale
Ca
Ag
As
Ba
Cd
Cr
Hg
Pb
Se
F~
Cl~
SOU2'
a
RSE -
.
X
5.6
<0.002
0.25
0.13
0.09
0.096
<0.004
<0.004
<0.02
b
b
1.8
o
p - x
Jn X
RSE
o ri / °/ \
1.13 2 14
- 2 -
0.021 2 5.9
0.014 2 7.6
0.003 2 2.4
0.034 2 25
- 2 -
2
2
- 2 -
- 2 -
0.28 2 11
100 percent.
Hopper ash
_
X a
8.9 0.23
<0.002 -
0.27 0.023
0.51 0.023
0.025 0.004
2.1 0.12
<0.004 -
<0.004 -
6.8 0.95
b
b -
8.4 1.45
n
3
3
3
3
3
3
3
3
3
3
3
3
RSE
1.5
4.9
2.6
9.2
3.3
8.1
9.8
Acetate interference.
69
-------
TABLE 39. CALCULATION OF RELATIVE STANDARD ERROR (RSE)a FOR EACH LEACHATE GENERATED BY THE EP
Oil shale
Ca
Ag
As
Ba
Cd
Cr
Hg
Pb
Se
F~
Cl~
so,,2-
a
RSE =
X
22
<0.01
0.28
4.8
<0.002
0.24
<0.02
0.47
<0.1
b
b
11
a
r~ - x
Jn X
RSE
CT n , ^,
0 20
2 -
0.057 2 14
2.83 2 42
2 -
0.064 2 19
2 -
0.24 2 36
2 -
2 -
2 -
2.26 2 15
100 percent .
FBC waste
X a
56 0
<0.01
0.15 0.028
7.4 0.28
0.011 0.010
0.27 0.042
<0.02
0.19 0.035
0.24 0
b
b
21.3 6.1
n
2
2
2
2
2
2
2
2
2
2
2
2
Bitur
flv
RSE
(%) X
0 2.9
- <1.2
13 29.3
2.7 <8.0
64 <0.5
11 <2.0
- <0.02
13 <10
0 2.0
b
b
20 3.9
linous coal
ash No. 1
RSE
0.58 3 12
3
7.1 3 14
3 -
3 -
3 -
3 -
- 3 -
0.97 3 28
3 -
- 3 -
0.31 3 46
Hopper ash
X a
44 0
<0.01
0.41 0.16
3.7 0.42
0.005 0.0046
4.5 1.9
<0.02
0.29 0.042
3.3 0.58
b
b
11.1 2.2
n
3
3
3
3
3
3
3
3
3
3
3
3
RSE
0
-
23
6.4
53
24
-
8.1
10
-
12
b
Acetate interference.
-------
TABLE 40. CALCULATION OF RELATIVE STANDARD ERROR (RSE)a FOR EACH LEACHATE
GENERATED BY THE CAE METHOD
Oil shale
Ca
Ag
As
Ba
Cd
Cr
Hg
Pb
Se
F~
Cl"
SO,,2"
a
RSE =
X
2.8
0.01
1.4
4.2
0.005
<0.016
<0.016
0.10
1.1
0.078
0.034
13.6
a
a
0.14
0
0.07
0.21
0.002
0.013
0.07
0.004
0
1.5
100 pen
n
2
2
2
2
2
2
2
2
2
2
2
2
cent
RSE
3.5
0
3.5
3.5
28
9.2
4.5
3.6
0
7.8
c.
Bituminous
fly ash No.
X
6.4
0.04
21
3.7
2.2
32
<0.016
2.2
0.52
0.17
0.11
45
a
0.71
0
0.71
0.21
0
3.5
0.071
0.021
0.021
0.007
0.71
coal
, 2
n
2
2
2
2
2
2
2
2
2
2
2
2
RSE
7.8
0
2.4
4.0
0
7.7
2.3
2.9
8.7
4.5
1.1
Hopper ash
X
3.3
<0.008
1.7
11.3
0.007
3.2
<0.016
0.13
7.0
0.04
0.025
4.4
a
0.23
0.23
0.12
0.002
0.25
0
1.3
0.016
0.001
0.4
n
3
3
3
3
3
3
3
3
3
3
3
3
RSE
4.0
8.1
0.64
17
4.5
0
11
23
2.3
5.3
Agitated at 120 cycles/minute.
-------
The following conclusions can also be drawn from the EPRI study:
1. Most of the variation in the results of the As, Ba, Cd,
and Pb analyses by graphite furnace and Ba and Se analysis
by flame AAS could be attributed to interlaboratory analysis
variability.
2. For all metals, most of the variation in the flame and
furnace results was due to the analytical method.
In addition to variation in the analyses, the reduced precision of the EP may
also be caused by several other factors. The EP was the only leachate test
that was not done in a closed system. In the open system, conditions are not
an strictly controlled and this could result in reduced precision. In the
EPRI study, a significant proportion of the variation in the graphite furnace
analyses of chromium and selenium was due to either interlaboratory or intra-
Inboratory extraction variability. Another source of nonreproducibility could
be the agitation method of the EP. The stirring device can grind particles on
the walls and bottom of the cylinder. This reduction in particle size exposes
new surfaces to be leached and is probably done in an irreproducible manner.
VARIATIONS IN LEACHATE PROCEDURES
Some of the leachate procedures were varied to determine the effect on the
leachate results. For example, data are presented in Table 41 for oil shale
leachate generated by altering the ASTM-A procedure. Since the agitation rate
suggested by ASTM is not very vigorous, the oil shale was extracted without
agitation (third and fourth run). The quantities extracted from the oil shale
without shaking are comparable to the concentrations leached while shaking at
60 cycles/minute. This is an indication that the agitation rate suggested by
ASTM do«s little to promote the exposure of the solid to the leaching solution.
The solubilization of species from the waste is largely a diffusion-controlled
process. In support of the slower agitation rate, it can be said that the
physical size of the sample will remain intact but this could be accomplished
under more vigorous conditions, too.
The oil shale was also leached by the ASTM-A method with the extraction
bottle lying horizontally on the reciprocating shaker. In this position, more
waste is exposed to the leachate and even the shaking rate of 60 cycles/minute
creates a wave motion that aids in exposing fresh solid to the solution. This
more effective mixing is evident in the analytical data (second run). For many
of the inorganic species, the amount leached has nearly doubled with the bottle
in a horizontal position.
The results are presented in Table 42 for extracts of bituminous coal fly
ash No. 2 generated by the ASTM-B and CAE methods. The leachates of ASTM-B
were generated at the normal agitation rate and at twice the rate (120 cycles/
minute) with the bottle in an upright position. There is little difference in
the data between the two leachates. The CAE method was conducted in duplicate
at the higher shaking rate to examine the effect on precision. The reproduci-
bility is comparable to that for the CAE method at the lower shaking rate.
72
-------
TABLE 41. COMPARISON OF ANALYTICAL DATA (IN
yg/g)a GENERATED BY VARIATIONS OF
ASTM-A PROCEDURE FOR OIL SHALE
Species
Ca (mg/g)
Ag
As
Ba
Cd
Cr
Hg
Pb
Se
F~ (mg/g)
Cl~ (mg/g)
SO!,2" (mg/g)
First
run
0.88
<0.004
0.44
<1.6
<0.0004
0.019
<0.004
0.064
0.17
0.016
0.009
4.9
Second
runb
1.8
0.008
0.92
0.36
0.002
0.048
<0.004
0.096
2.1
0.026
0.015
9.5
Third
runc
0.52
0.006
0.56
0.40
0.002
0.028
<0.004
0.052
0.84
0.012
0.016
7.9
Fourth
run0
0.4
0.005
0.48
0.42
0.002
0.021
<0.004
0.052
0.84
0.012
0.010
5.9
a
Unless otherwise indicated, concentration in
Ug/g of dry waste.
Leachate generated with bottle lying horizon-
tally on shaker.
Q
Leachate was not shaken.
The combined results for the variations in the ASTM methods suggest that
the means of agitation must be changed if the leachate is to be an indication
of the maximum impact of the waste disposal upon the environment. It appears
that merely increasing the rate of the reciprocating shaker, as has been sug-
aested by ASTM in a recent revision to its proposed methods, will not yield
f significant increase in the mixing of the solid and leaching medium. Recent
data generated by ASTM have shown statistical significance when the ASTM-A was
at 180 cycles/minute vs. 60 cycles /minute.
COMPATIBILITY WITH ENVIRONMENTAL ASSESSMENT PROCEDURES
The inherent toxic ity of the EP leachate to various bioassay tests has been
documented by the results of the work at Oak Ridge National Laboratory.1 The
acetate ion poses problems with aquatic toxicity and phytotoxicity tests. Ex-
periments have shown that acetate ion is phytotoxic. The chronic aquatic bio-
assay uses the reproduction of daphnia magna to determine the toxicity of waste
extracts. It is believed that the acetate in the extracts may serve as a aub-
atrate for the bacteria. The bacteria are fed on by the daphnids causing an
artificial increase in the production of young. In control experiments, the
73
-------
production of young was significantly higher for acetic acid solutions than for
extracts using only water. The same would be true of the buffer solution in
the ASTM-B method and this problem was a source of major concern in the synthetic
leachate developed by Ham at the University of Wisconsin. **
TABLE 42. COMPARISON OF LEACHATE DATA (IN
Wg/g)a FOR BITUMINOUS COAL FLY
ASH NO. 2
ASTM-B
CAE
Species
First Secondb First Secondb
Ca (mg/g)
Ag
As
Ba
Cd
Cr
Hg
Pb
Se
F~ (mg/g)
Cl~ (mg/g)
SOt,2' (mg/g)
2.4
0.18
17
0.38
1.6
46
<0.004
2.4
<0.02
c
c
41
2.2
0.10
18
0.44
1.9
46
<0.004
3.7
<0.02
c
c
46
6.9
0.04
21
3.8
2.2
34
<0.016
2.2
0.53
0.15
0.11
45
5.9
0.04
20
3.5
2.2
29.0
0.019
2.1
0.50
0.18
0.10
44
f\
given in Mg/g of dry waste.
Agitated at 120 cycles/minute.
C
Acetate interference.
The acetic acid matrices of the ASTM-B and EP also caused some analytical
problems. It is possible that none of these problems was observed in
previous investigations because the amount of 0.5 N acetic acid added during
the EP varies from one waste to another. In many of the wastes tested in this
study, the maximum volume of acetic acid (400 ml) was added during the experi-
ment. These acidic media caused rapid deterioration of the graphite tubes.
Standard solutions had to be injected more frequently to monitor the condition
of the graphite tubes. This resulted in increased analytical time, and, with
more frequent tube replacement, increased expense. The acetic acid matrices
produced some initial background problems. Analyses for lead in the leachates
generated by the ASTM-B and CAE methods could be achieved only by using the
deuterium background correction capabilities of the instrument.
74
-------
It is also possible that the acetic acid matrix caused some of the varia-
tion in the results observed for the EP. The injection of strong acidic solu-
tions into the graphite furnace can degrade the analytical precision. The
strong acidic solutions "wet" the inner surface of the graphite tube and cause
variable distribution of the injected sample. This variable distribution will
reduce the precision of replicate injections. If the absorbance data are
examined for the injections of the EP leachates, it is apparent that the repro-
ducibility has been degraded for replicate injections. However, the reduced
analytical precision for the EP does not sufficiently account for the differences
in precision between the EP and the other three leachate tests.
The acetate ion in the ASTM-B and EP solutions interfered with the deter-
mination of fluoride and chloride in the 1C analyses. The retention time of
the acetate ion is comparable to the retention times of the fluoride and chloride
iona and its presence in large excess masked the determination of the fluoride
and chloride concentrations.
No problems were encountered during the analysis of the leachates generated
by the ASTM-A or CAE methods. The presence of carbonic acid is effectively
suppressed during the 1C analysis.
Since SSMS is utilized in EA programs for the elemental analysis of various
environmental samples, the compatibility of the leachate with SSMS analysis
was investigated. SSMS data for the EP leachate of bituminous coal fly ash No. 1
and the EP leachate blank are presented in Appendix B. The EP leachate of the
fly ash posed no problems during the electrode preparation and subsequent SSMS
analysis. Although no SSMS data are reported in this study for leachates gen-
erated by the ASTM-A method, SSMS analyses of ASTM-A leachates generated pre-
viously in our laboratory have not indicated any analytical problems.
It can be argued that the analytical problems indicated in this study
would not be encountered in the proposed RCRA analytical scheme. Since AAS
analys68 are to be done by flame techniques, the problems associated with the
graphite furnace would not exist. In addition, it is not necessary to determine
the exact concentration of the metal in the leachate, but just show that its
concentration is below the proposed threshold level. To do this, flame AAS
would be sufficient. Since 1C analyses of the anions is not specified in the
RCRA procedures, the acetate problem associated with the 1C is not important
cither.
However, it is possible that in the future the RCRA criteria could become
more stringent and the maximum allowable concentrations would be reduced. This
reduction in the threshold level might necessitate the use of the graphite fur-
nace to quantitate the metals in the leachate. If this were to happen, the
problems cited above would become relevant to the selection of a standard
leachate test.
75
-------
REFERENCES
1. Epler, J.L., W.H. Griest, M.R. Guerin, M.P. Maskarinec, D.A. Brown
N.T. Edwards, C.W. Gehrs, B.R. Parkhurst, B.M. Ross-Todd, D.S. Shriner,
H.W. Wilson, F.W. Larimer, and T.K. Rao. Toxicity of Leachates. Interim
Progress Report. April 1, 1978 to January 1, 1979. Oak Ridge National
Laboratory, Oak Ridge, Tennessee. Prepared for Office of Solid Waste and
U.S. Environmental Protection Agency. EPA-IAG-78-D-X0372. 121 pp.
2. Ham, R., M.A. Anderson, R. Stegmann, and R. Stanforth. Background Study
on the Development of a Standard Leaching Test. EPA-600/2-79-109.
U.S. Environmental Protection Agency, Cincinnati, Ohio. 1979. 249 pp.
3. Lowenbach, W. Compilation and Evaluation of Leaching Test Methods.
EPA-600/2-78-095. U.S. Environmental Protection Agency, Cincinnati,
Ohio. 1978. 102 pp.
4. Ham, R.K., M.A. Anderson, R. Stegmann, and R. Stanforth. Comparison of
Three Waste Leaching Tests. EPA-600/2-79-071. U.S. Environmental
Protection Agency, Cincinnati, Ohio. 1979. 214 pp.
5. Methods for Chemical Analysis of Water and Wastes. EPA-600/4-79-020.
U.S. Environmental Protection Agency, Cincinnati, Ohio. 1979. 430 pp.
6. Ham, R.K., M.A. Anderson, R. Stegmann, and R. Stanforth. Comparison of
Three Waste Leaching Tests, Executive Summary. EPA-600/8-79-001.
U.S. Environmental Protection Agency, Cincinnati, Ohio. 1979. 24 pp.
7. Wewerka, E.M., J.M. Williams, N.E. Vanderborgh, A.W. Harmon, P. Wagner,
P.L. Wanek, and J.D. Olsen. Trace Element Characterization of Coal Wastes
Second Annual Progress Report. EPA-600/7-78-028a. U.S. Environmental
Protection Agency, Washington, D.C. 1978. 144 pp.
8. Weeter, D.W., and M.P. Bahor. Technical Aspects of the Resource Conserva-
tion and Recovery Act Upon Coal Combustion and Conversion Systems. Depart-
ment of Civil Engineering, University of Tennessee, Knoxville, Tennessee.
Prepared for Office of Environmental Policy Analysis, Oak Ridge National
Laboratory, Oak Ridge, Tennessee. ORNL/OEPA-10. 1979. 73 pp.
9. Meier, E.P., L.R. Williams, R.G. Seals, L.E. Holboke, and D.C. Hemphill.
Evaluation of the Procedures for Identification of Hazardous Waste,
Interim Report, August 1979. EPA Environmental Monitoring Systems
Laboratory, Las Vegas, Nevada. 1979. 43 pp.
76
-------
10. Kurd, R.M., and J.M. Riddle. Evaluation of Solid Waste Extraction Pro-
cedures and Various Hazard Identification Tests. Cyrus Wm. Rice Division,
NUS Corporation, Pittsburgh, Pennsylvania. EPA Contract No. 68-01-4725.
1979. 85 pp.
11. American Society for Testing and Materials, interlaboratory evaluation of
EP and ASTM Methods. Report submitted for publication 1979.
12. Theis, T.L., and J.L. Wirth. Sorptive Behavior of Trace Metals on Fly Ash
in Aqueous Systems. Environmental Science and Technology, 11, 1096-1100.
1977.
13. Henry, W.M. Methods for Analyzing Inorganic Compounds in Particles Emitted
from Stationary Sources, Interim Report. EPA-600/7-79-206. U.S. Environ-
mental Protection Agency, Research Triangle Park, North Carolina. 1979.
122 pp.
14. Dreesen, D.R., L.I. Wangen, E.S. Gladney, and J.W. Owens. Solubility of
Trace Elements in Coal Fly Ash. In: Environmental Chemistry and Cycling
Processes, proceedings of a symposium held at Augusta, Georgia. 1976.
pp. 240-252.
15. Linton, R.W., A. Loh, D.F.S. Natusch, C.A. Evans, Jr., and P. Williams.
Surface Predominance of Trace Elements in Airborne Particles. Science,
191, 852-854. 1976.
16. Natusch, D.F.S., J.R. Wallace, and C.A. Evans, Jr. Toxic Trace Elements:
Preferential Concentration in Respirable Particles. Science, 183, 202-204.
1974.
17. Electric Power Research Institute. Proposed RCRA Extraction Procedure:
Reproducibility and Sensitivity. Palo Alto, California. 27 pp.
77
-------
APPENDIX A
TABLES OF LEACHATE CONCENTRATIONS OF INORGANIC CONTAMINANTS
(UNLESS OTHERWISE INDICATED IN THE TABLES,
THE CONCENTRATIONS ARE GIVEN IN yg/1)
TABLE A-l. CONCENTRATIONS OF INORGANIC SPECIES
IN OIL SHALE LEACHATE GENERATED BY
THE ASTM-A METHODa
Species
Ca Ug/l)b
Ag
As
Bab
Cd
Cr
Hg
Pb
Se
F~ (mg/1)
Cl~ (mg/1)
SOiT (mg/1)
Preserved
220
1.0
110
<400
<0.1
4.7
<1.0
16
41
3.9
2.3
1230
Reserve
220
1.6
83
<400
<0.1
5.5
<1.0
18
41
Final pH: 9.88.
Analyzed by flame AAS.
78
-------
TABLE A-2. CONCENTRATIONS OF INORGANIC SPECIES IN OIL
VO
SHALE LEACHATE GENERATED
BY VARIATIONS OF
TABLE A-3
THE ASTM-A METHOD
Final pH
Species
Cac (mg/1)
Ag
As
Ba
Cd
Cr
Hg
Pb
Se (yg/1)
F~ (mg/1)
Cl~ (mg/1)
S0^~ (mg/1)
a
First
a
run
11.13
460
2.0
230
90
0.6
12.0
<1.0
24
530d
6.6
3.8
2370
2L LPE Bottle placed
b
Second
b
run"
10.74
130
1.5
140
100
0.4
7.1
<1.0
13.0
210d
2.9
3.9
1960
horizontally on
Third run
10.74
100
1.3
120
105
0.4
5.2
<1.0
13.0
210d
3.0
2.4
1480
shaker .
Leaching mixtures were not shaken.
Analvzed bv flamp AAS .
Final pH
Species
Ca (mg/l)a
Ag
As
Ba
Cd
Cr
Hg
Pb
Se
_ f 1 1 \
F (mg/1)
Cl" (mg/1)
S0%~ (mg/1)
. CONCENTRATIONS OF
INORGANIC SPECIES
IN OIL SHALE
LEACHATE GENERATED
BY THE ASTM-B
\j"C"T»Tj/-\Tx
METHOD
First Second
replicate replicate
5.09 5.32
1200 1600
<0.5 <0.5
64 58
34 31
22 23
31 18
<1.0 <1.0
<1.0 <1.0
<5.0 <5.0
Acetate interference
Acetate interference
400 510
Exceeds RCRA criteria.
Analyzed by flame AAS.
-------
TABLE A-4. CONCENTRATIONS OF INORGANIC
SPECIES IN OIL SHALE
LEACHATE GENERATED BY THE EP
TABLE A-5. CONCENTRATIONS OF INORGANIC SPECIES IN
OIL SHALE LEACHATE GENERATED BY THE CAE
First Second
replicate replicate
Initial pH
Final pH
Volume acid added (ml)
Species
Ca (mg/l)a
Ag
As
oo Ba
o
Cd
Cr
Hg
Pb
Se
F~ (mg/1)
Cl~ (mg/1)
10.7
8.7
400
1100
<0.5
12
140
<0.1
14
<1.0
32
<5.0
Acetate
Acetate
630
10.8
8.5
400
1100
<0.5
16
340
0.3
9.3
1.0
15
13
interference
interference
470
First replicate
Final pH
Species
Ca (mg/1) a
Ag
As
Ba
Cd
Cr
Hg
Pb
Se
F~ (mg/1)
Cl~ (mg/1)
S02- (rag/1)
Analyzed by
6.64
Preserved
170
0.6
85
250
0.4
1.4
<1.0
7.1
66
5.0
2.1
780
flame AAS.
Second replicate
6.58
Reserve
130
0.5
89
240
0.7
1.0
<1.0
6.1
59
Preserved
180
0.6
82
270
0.2
<1.0
<1.0
5.7
63
4.7
2.1
910
Reserve
160
0.
87
260
0.
<1.
1.
5.
"60
5
3
0
2
6
Analyzed by flame AAS.
-------
oo
TABLE A-6. CONCENTRATIONS OF INORGANIC SPECIES IN
FBC WASTE LEACHATE GENERATED BY THE
ASTM-A METHOD
TABLE A-7,
First replicate
Final pH
Species
Ca (mg/l)3
Ag
As
Baa
Cd
Cr
Hg
Pb
Se
F- (mg/1)
Cl~ (mg/1)
S0£~ (mg/1)
12.
Preserved
960
<0.5
37
<400
0.4
62
<1.0
9.0
40
1.2
5.0
950
52
Reserve
930
<0.5
33
<400
0.3
58
<1.0
7.9
44
Second replicate
12.
Preserved
1000
<0.5
34
<400
0.4
29
<1.0
12
40
1.2
7.5
1230
54
Reserve
1020
<0
33
<400
0
34
<1
10
42
.5
.4
.0
Species
Ca (mg/1)1
Ag
Cd
Cr
Hg
Pb
Se
F~ (mg/1)
Cl~ (mg/1)
SQ2- (mg/1)
CONCENTRATIONS OF
INORGANIC SPECIES
IN FBC WASTE
LEACHATE GENERATED
BY THE ASTM-B
METHOD3
2700
<0.5
17
110
<1.0
<5.0
Acetate interference
Acetate interference
510
Analyzed by flame AAS.
Final pH: 11.94.
Analyzed by flame AAS.
-------
oo
ro
TABLE A-8. CONCENTRATIONS OF INORGANIC SPECIES IN
FBC WASTE LEACHATE GENERATED BY THE EP
First Second
replicate replicate
Initial pH 12.47 12.52
Final pH 12.28 12.32
Volume acid added (ml) 400 400
TABLE A-9.
Species
Preserved Reserve Preserved Reserve
Caa (mg/1)
Ag
As
Ba
Cd
Cr
Hg
Pb
Se
F~ (mg/1)
Cl~ (mg/1)
2800
<0.5
8.5
360
0 .2
12
<1. 0
8.2
12
2800
<0.5
6.3
310
2.5
38
1.2
9.9
13
2800
<0.5
6.7
380
0.9
15
1.0
10
12
2800
<0.5
6.3
350
2.3
40
1.3
12.6
13
SO
(mg/1) 850
Acetate interference
Acetate interference
1280
CONCENTRATIONS OF
INORGANIC SPECIES
IN FBC WASTE
LEACHATE GENERATED
BY THE CAEa
Species
Cab (mg/1)
Ag
As
Ba
Cd
Cr
Hg
Pb
Se
F" (mg/1)
Cl~ (mg/1)
SO£- (mg/1)
Preserved
270
0.6
25
71
<0.1
16.7
<1.0
5.8
28
0.6
3.0
160
Reserve
190
0.5
30
83
0.2
17.1
1.2
4.1
40
Final pH: 11.74.
Analyzed by flame AAS.
Analyzed by flame AAS.
-------
TABLE A-10.
oo
CONCENTRATIONS OF
INORGANIC SPECIES
IN BITUMINOUS COAL
FLY ASH NO. 1
LEACHATE GENERATED
BY THE ASTM-A
METHOD3
TABLE 11.
Cab (mg/1)
Agb
As
Bab
Cdb
Crb
Hg
Pbb
Se
F- (mg/1)
Cl~ (mg/1)
SOj- (mg/1)
190
<60
370
<400
<25
<100
1.0
<500
160C
1.0
1.0
260
Final pH: 10.4.
Analyzed by flame AAS.
"Exceeds RCRA criteria.
CONCENTRATIONS OF
INORGANIC SPECIES
IN BITUMINOUS COAL
FLY ASH NO. 1
LEACHATE GENERATED
BY THE ASTM-B
METHOD3
Cab (mg/1)
Agb
As
Bab
Cdb
Crb
Hg
Pb
Se
F~ (mg/1)
Cl" (mg/1)
soj~
270
<60
2430C
<400
<25
300
<1.0
<500
140C
d
d
300
Final pH: 4.5.
Analyzed by flame AAS.
c
Exceeds RCRA criteria.
Acetate interference.
-------
TABLE A-12. CONCENTRATIONS OF INORGANIC SPECIES IN
BITUMINOUS COAL FLY ASH NO. 1 LEACHATE
GENERATED BY THE EP
Initial pH
Final pH
Volume acid added (ml)
Caa (mg/1)
Aga
As
Baa
Cda
Cra
Hg
Pba
Se
F~ (mg/1)
Cl~ (mg/1)
S0'{~ (mg/1)
First
replicate
8.9
5.0
15.7
108
<60
1120b
<400
<25
<100
<1.0
<500
110b
c
c
180
Second
replicate
9.0
5.0
22.9
158
<60
1440b
<400
<25
<100
<1.0
<500
140b
c
c
200
Third
replicate
8.3
5.0
24.4
161
<60
1830b
<400
<25
<100
<1.0
<500
45
c
c
210
Analyzed by flame AAS.
Exceeds RCRA criteria.
"Acetate interference.
84
-------
TABLE A-13. CONCENTRATIONS OF INORGANIC SPECIES IN
BITUMINOUS COAL FLY ASH NO. 2 LEACHATE
GENERATED BY THE ASTM-B METHOD
Final pH
Species
Cab Ug/1)
Ag
As
Ba
Cd
Cr
Hg
Pb
Se
F~ (mg/1)
Cl" (mg/1)
SO*' (mg/1)
Run 1
(60 cycles /min)
3.28
600
44
4300C
95
400
11,400C
<1.0
600C
<5.0
Acetate
Acetate
10,300
Run 2
(120 cycles/min)a
3.51
540
26
4500°
110
480
11,500C
<1.0
930C
<5.0
interference
interference
11,400
Agitation rate.
Analyzed by flame AAS.
"Exceeds RCRA criteria.
85
-------
00
TABLE A-14. CONCENTRATIONS OF INORGANIC SPECIES IN
BITUMINOUS COAL FLY ASH NO. 2 LEACHATE
GENERATED BY THE CAE
First replicate
(120 cycles /min)
Final pH
Species
Cab (mg/1)
Ag
As
Ba
Cd
Cr
Hg
Pb
Se
F" (mg/1)
Cl~ (rag/1)
SO*" (mg/1)
3.
Preserved
430
2.5
1320C
240
140
2150C
<1.0
140
33
9.3
6.7
2830
11
Reserve
420
1.9
1280C
270
140
2090C
<1.0
100
32
Second replicate
(120 cycles/min)3
3.
Preserved
370
2.5
1270C
220
140
1810°
1.2
130
31
11.0
6.1
2740
08
Reserve
370
2.1
1310C
230
140
1740C
1.5
150
34
Agitation rate.
Analyzed by flame AAS.
^
'Exceeds RCRA criteria.
TABLE A-15.
CONCENTRATIONS OF
.INORGANIC SPECIES
IN BOILER SLAG
LEACHATE GENERATED
BY THE ASTM-A
METHOD3
Species Preserved
Cab (mg/1) 1.5
Ag <0 . 5
As < 1 . 0
Bab <400
Cd <0.1
Cr <1.0
Hg <1.0
Pb <1.0
Se <5.0
F' (mg/1) <1.0
Cl~ (mg/1) <1.0
S0*~ (mg/1) 12
Reserve
1.8
<0.5
<400
7.9
*Final pH: 3.55.
Analyzed by flame AAS.
-------
TABLE A-16.
00
CONCENTRATIONS OF
INORGANIC SPECIES
IN BOILER SLAG
LEACHATE GENERATED
BY THE ASTM-B
TABLE A-17.
CONCENTRATIONS OF
INORGANIC SPECIES
IN BOILER SLAG
LEACHATE GENERATED
BY THE CAEa»b
TABLE A-18.
CONCENTRATIONS OF
INORGANIC SPECIES
IN SCRUBBER SLUDGE
LEACHATE GENERATED
BY THE ASTM-A
Species
Cab (mg/1)
Ag
As
Ba
Cd
Cr
Hg
Pb
Se
F~ (mg/1)
Cl" (mg/1)
SO£~ (mg/1)
METHOD"
7.1
<0.5
24
29
3.8
4.4
<1.0
<1.0
<5.0
Acetate interference
Acetate interference
33
Species
Cac (mg/1)
Ag
As
Ba
Cd
Cr
Hg
Pb
Se
F~ (mg/1)
Cl~ (mg/1)
SQ2- (mg/1)
f\
Preserved
0.6
<0.5
<1.0
12.0
<0.1
<1.0
1.2
<1.0
<5.0
<1.0
1.5
4.1
= L" METHC
p,b (Tno./i\
oa vmg/ i i
°'6
<0'5 As
-------
TABLE A-19.
oo
00
CONCENTRATIONS OF
INORGANIC SPECIES
IN SCRUBBER SLUDGE
LEACHATE GENERATED
BY THE ASTM-B
TABLE A-20.
Analyzed by flame AAS.
»
"Exceeds RCRA criteria.
Acetate interference.
CONCENTRATIONS OF
INORGANIC SPECIES
IN SCRUBBER SLUDGE
LEACHATE GENERATED
BY THE EPa
TABLE 21.
CONCENTRATIONS OF
INORGANIC SPECIES
IN SCRUBBER SLUDGE
LEACHATE GENERATED
BY THE CAEa
METHC
Cab (mg/1)
*»&
As
Bab
Cdb
Crb
Hg
Pbb
Se
F~ (mg/1)
Cl~ (mg/1)
4
a
Final r>H; 4.5.
)Da
690
<60
350
<400
<25
<100
1.0
<500
130C
d
d
2260
Cab (mg/1)
As
Bab
f*. «D
Cd
K
CrD
Hg
Pbb
Se
F~ (mg/1)
Cl~ (mg/1)
alnitial pH: 5.6
Pir.=,1 T>H- SI
510
<60
140
<400
<25
<100
<1.0
<500
110
A. A V/
d
d
1300
Species
K
Ca (mg/1)
Ag
As
Ba
Cd
Cr
Hg
Pb
Se
F~ (mg/1)
Cl~ (mg/1)
SQ2- (mg/1)
Preserved
600
1.0
160
73
1.4
1.2
<1.0
13.9
15QC
2.2
3.9
1480
Reserve
620
0.8
170
77
1.3
1.4
1.4
14.2
120C
Volume acid added (ml): 13.5
Analyzed by flame AAS.
cExceeds RCRA criteria.
Acetate interference.
Final pH: 5.43.
Analyzed by flame AAS.
cExceeds RCRA criteria.
-------
00
TABLE 22. CONCENTRATIONS OF INORGANIC
SPECIES IN HOPPER ASH LEACHATE
GENERATED BY THE ASTM-A METHOD
Analyzed by flame AAS.
[j
Exceeds RCRA criteria.
TABLE A-23. CONCENTRATIONS OF INORGANIC
SPECIES IN HOPPER ASH LEACHATE
GENERATED BY THE ASTM-B METHOD
Final pH
Species
Ca (mg/1)
Ag
As
Ba
Cd
Cr
Hg
Pb
Se
F~ (mg/1)
Cl" (mg/1)
SOJ|~ (mg/1)
First
replicate
12.13
470
<0.5
27
1870
<0.1
120
<1.0
7.7
410b
9.6
1.0
150
Second
replicate
12.16
490
<0.5
27
2250
0.1
120
<1.0
7.9
550b
9.7
1.0
190
Third
replicate
12.16
430
<0.5
24
1810
<0.1
110
<1.0
8.5
470b
9.8
1.0
200
Final pH
Species
Caa (mg/1)
Ag
As
Ba
Cd
Cr
Hg
Pb
Se
F~ (mg/1)
Cl~ (mg/1)
S02- (mg/1)
First
replicate
11.03
2300
<0.5
70
120
6.8
540b
<1.0
<1.0
1460b
Acetate
Acetate
2450
Second
replicate
11.04
2200
<0.5
70
130
4.9
510b
<1.0
<1.0
1930b
Third
replicate
11.02
2200
<0.5
60
130
6.9
490b
<1.0
<1.0
1700b
interference
interference
2100
1720
Analyzed by flame AAS.
^Exceeds RCRA criteria.
-------
VD
O
TABLE A-24. CONCENTRATIONS OF INORGANIC SPECIES IN
HOPPER ASH LEACHATE GENERATED BY THE EP
TABLE A-25. CONCENTRATIONS OF INORGANIC
First Second Third
replicate replicate replicate
Initial pH
Final pH
Volume acid added (ml)
Species
Caa (mg/1)
Ag
As
Ba
Cd
Cr
Hg
Pb
Se
F~ (mg/1)
Cl~ (mg/1)
S02~ (mg/1)
12.05
9.44
400
2200
<0.5
15
210
0.5
190
<1.0
13
200b
Acetate
Acetate
670
12.03 12.00
10.37 10 .,22
400 400
2200 2200
<0.5
30
180
0.1
150
<1.0
14
150b
interference
interference
450
<0.5
17
170
0.1
330
<1.0
17
150b
550
SPECIES IN HOPPER ASH LEACHATE
GENERATED BY THE CAE
Final pH
Species
Caa (mg/1)
Ag
As
Ba
Cd
Cr
Hg
Pb
Se
F~ (mg/1)
Cl~ (mg/1)
sojf
a
Analyzed by
First
replicate
7.30
190
<0.5
89
710
0.4
180
<1.0
8.4
350b
2.0
1.6
250
flame AAS.
Second
replicate
7.25
210
<0.5
110
710
0.6
210
<1.0
8.0
470b
2.1
1.6
280
Third
replicate
7.33
210
<0.5
110
700
0.4
200
<1.0
8.2
500b
3.3
1.5
300
Analyzed by flame AAS.
Exceeds RCRA criteria.
Exceeds RCRA criteria.
-------
APPENDIX B
SPARK SOURCE MASS SPECTROGRAPHY DATA FOR THE EP
LEACHATE OF BITUMINOUS COAL FLY ASH NO. 1 AND
THE EP LEACHATE BLANK
91
-------
TABLE B-l. SSMS DATA FOR THE EP LEACHATE OF BITUMINOUS
COAL FLY ASH NO. 1
Element Concentration (ug/ml) Element Concentration (ug/ml)
Uranium
Thorium
Bismuth
Lead
Thallium
Mercury
Gold
Platinum
Iridium
Osmium
Rhenium
Tungsten
Tantalum
Hafnium
Lutecium
Ytterbium
Thulium
Erbium
Ho Imium
Dysprosium
Terbium
Gadolinium
Europium
Samarium
Neodymium
Praseodymium
Cerium
Lanthanum
Barium
Cesium
Iodine
TeJ lurium
Antimony
TJn
Ind ium
Cadmium
Silver
Pal lad ium
Rhodium
NDa
ND
ND
ND
ND,
NRb
ND
NR
ND
ND
ND
ND
NR
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
0.12
0.005
0.007
ND
0.043
ND
ISC
0.001
NR
ND
ND
Ruthenium
Molybdenum
Niobium
Zirconium
Yttrium
Strontium
Rubidium
Bromine
Selenium
Arsenic
Germanium
Gallium
Zinc
Copper
Nickel
Cobalt
Iron
Manganese
Chromium
Vanadium
Titanium
Scandium
Calcium
Potassium
Chlorine
Sulphur
Phosphorus
Silicon
Aluminum
Magnesium
Sodium
Fluorine
Oxygen
Nitrogen
Carbon
Boron
Beryllium
Lithium
ND
0.14
ND
ND
ND
0.88
0.037
0.033
0.069
0.49
0.80
ND
0.16
0.069
0.15
0.022
0.023
0.14
0.003
0.35
0.065
NR
210
11
0.23
5.7
0.94
4.4
0.28
4.8
4.9
0.032
NR
NR
NR
0.084
<0.001
0.10
ND - not detected.
NR - not reported.
"IS - internal standard.
92
-------
TABLE B-2. SSMS DATA FOR THE EP LEACHATE BLANK
Element Concentration (vig/ml)
Uranium
Thorium
Bismuth
Lead
Thallium
Mercury
Gold
Platinum
Iridium
n mium
Rhenium
Tungsten
Tantalum
f nium
Lutecium
Ytterbium
Thulium
X «
Erbium
Dysprosium
Terbium
Gadolinium
Europium
Samarium
Neodymium
praseodymium
Cerium
Lanthanum
Barium
Cesium
Iodine
Tellurium
Antimony
Tin
Indium
Cadmium
Silver
Palladium
Rhodium
<0.005
<0.006
<0.002
O.003
<0.002
NRa
<0.001
NR
<0.002
<0.002
<0.001
<0.008
NR
<0.014
<0.002
<0.013
-------
TECHNICAL REPORT DATA
(Please read I untrue turns on the reverse before completing)
i Rt PORT NO
EPA-600/7-80-118
2.
3. RECIPIENT'S ACCESSION NO.
4. TITLE AND SUBTITLE Comparison of Four Leachate-
generation Procedures for Solid Waste Characteriza-
tion in Environmental Assessment Programs
5. REPORT DATE
May 1980
6. PERFORMING ORGANIZATION CODE
7. AUTHORIS)
Daniel E. Bause and Kenneth T. McGregor
8. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORGANIZATION NAME AND ADDRESS
GCA/Technology Division
213 Burlington Road
Bedford, Massachusetts 01730
1O. PROGRAM ELEMENT NO.
1AB604
11. CONTRACT/GRANT NO.
68-02-3129, Task 103
12. SPONSORING AGENCY NAME AND ADDRESS
EPA, Office of Research and Development
Industrial Environmental Research Laboratory
Research Triangle Park, NC 27711
PERIOD COVERED
14. SPONSORING AGENCY CODE
EPA/600/13
16. SUPPLEMENTARY NOTES IERL_RTp
919/541-2557.
officer is Frank E. Briden , Mail Drop 62,
ie. ABS RACT The report gives results of an evaluation of four leachate-generating pro-
cedures in terms of their general applicability, reproducibility, compatibility with
environmental assessment methods, and leaching characteristics. The generated
leachates were analyzed for nine metals by atomic absorption, and for F(-), Cl(-),
and SO4(-~) by ion chromatography. Seven energy process wastes (oil shale, FBC
waste, two flyashes, boiler slag, scrubber sludge, and hopper ash) were extracted
to evaluate the general applicability of the leachate tests. The ASTM methods had
the best reproducibility, and the EP method, the poorest. The EP and CAE proce-
dures leached the largest quantities of trace metals from the wastes. However,
based on the total metal concentration in the sample, the leachate methods generally
extracted < 1%. The EP and ASTM-B methods caused some problems with flameless
AA analyses. Based on the RCRA criteria, five of the energy wastes would be class-
ified as hazardous by at least one leachate procedure. Se usually exceeded the thres-
hold value for the leachate. Based on this study, the ASTM-A and CAE procedures
are preferred for leachate generation. Regardless of the leachate-generating method
selected for waste characterization, the experimental procedure must be defined
more precisely with respect to preparation, preservation, and other aspects.
7.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
Ipollution
Leaching
Wastes
Analyzing
Properties
Assessments
Qil Shalp
Fluidized Bed Pro-
cessing
Combustion
Fly Ash
Slags
Sludge
Ashes
b.IDENTIFIERS/OPEN ENDED TERMS
Pollution Control
Stationary Sources
Leachates
Solid Waste
Characterization
Environmental Assess-
ment
COSATi Held/Group
13B
07D,07A
14G
14B
13H
21B
18. DISTRIBUTION STATEMENT
Release to Public
19. SECURITY CLASS (This Report)
Unclassified
21. NO. OF PAGES
105
20. SECURITY CLASS (This page)
Unclassified
22. PRICE
form 2220-1 (t-73)
95
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