&EPA
             United States
             Environmental Protection
             Agency
             Municipal Environmental Research  EPA 600 8 79 001
             Laboratory          May 1979
             Cincinnati OH 45268
             Research and Development
Comparison of
Three Waste
Leaching Tests
             Executive Summary

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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 "SPECIAL" REPORTS series This series is
reserved for reports targeted to meet the technical information needs of specific
user groups The series includes problem-oriented reports, research application
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analyses, technology assessments, design manuals, user manuals, and reports
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This document is available to the public through the National Technical Informa-
tion Service, Springfield, Virginia  22161.

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                                            EPA-600/8-79-001
                                            May 1979
       COMPARISON  OF  THREE  WASTE  LEACHING  TESTS

                   Executive  Summary
                          by

                     Robert  K.  Ham
                   Marc  A. Anderson
                    Rainer Stegmann
                   Robert  Stanforth
   Department of Civil and Environmental  Engineering
            University of  Wisconsin-Madison
               Madison,  Wisconsin   53706
                 Grant No.  R-804773-01
                   Project Officers

                   Michael  Gruenfeld
         Industrial  Pollution Control  Division
Industrial  Environmental  Research  Laboratory-Cincinnati
               Edison,  New Jersey   08817

                    Donald Sanning
      Solid and Hazardous Waste Research  Division
      Municipal Environmental Research Laboratory
                Cincinnati, Ohio  45268
     INDUSTRIAL ENVIRONMENTAL RESEARCH LABORATORY
          OFFICE OF RESEARCH AND DEVELOPMENT
         U.S.  ENVIRONMENTAL PROTECTION AGENCY
                CINCINNATI, OHIO  45268

      MUNICIPAL ENVIRONMENTAL RESEARCH LABORATORY
          OFFICE OF RESEARCH AND DEVELOPMENT
         U.S.  ENVIRONMENTAL PROTECTION AGENCY
                CINCINNATI, OHIO  45268

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                                 DISCLAIMER
      This Executive Summary has been reviewed by the Industrial  Environmental
Research Laboratory, the Municipal Environmental Research Laboratory and the
Office of Solid Waste, U.S. Environmental Protection Agency and approved for
publication.  Approval does not signify that the contents necessarily reflect
the views and policies of the U.S. Environmental Protection Agency, nor does
mention of trade names or commercial products constitute endorsement or
recommendation for use.

      The selection or design of any leachate test will ultimately be decided
by a number of practical, rather than theoretical, considerations.  The class-
ification of whether or not a waste is hazardous, via a leaching test, must
assume less than ideal disposal conditions, in order that, its potential for
causing environmental harm can be minimized.  It is recognized that a single
test will not be optimal for all disposal conditions.  Nevertheless from a
regulatory point of view, developing different tests for each different waste
and disposal option is clearly impractical and probably unworkable.

      This Executive Summary is published with the intent of providing quick
and concise information on the results and findings of this project.
                                      11

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                                  FOREWORD
     This research effort is a combined response to  an  environmental  need by
two Office of Research and Development Laboratories.   The Edison,  New Jersey
office of the Industrial  Environmental  Research  Laboratory assisted the Muni-
cipal  Environmental  Research Laboratory in  this  effort.

     The Industrial  Environmental  Research  Laboratory-Cincinnati  develops cost
effective techniques to prevent,  control, or abate multi-media  (air,  water,
solid wastes, etc.)  pollutional  impacts associated with  the extraction, trans-
portation, processing, benefication,  conversion, and  use of mineral  resources
and with industrial  processing and manufacturing.  The  Municipal  Environmental
Research Laboratory develops new and  improved technology and systems  for pre-
venting, treating, and managing waste water and  solid and hazardous waste
pollutant discharges from municipal  and community sources, for  preserving and
treating public drinking water supplies, and for minimizing the adverse eco-
nomic, social, health, and aesthetic  effects of  pollution.  The related pollu-
tional impacts on our environment and the interplay  between its components
require a concentrated and integrated attack on  the  problem.

     This report deals with the investigation of three  leaching tests as
reliable predictors  of the potential  environmental effects of the  disposal of
thirteen industrial  wastes.  The  advantages and  disadvantages of each test
based on the leaching characteristics of the thirteen wastes and the  useful-
ness of each procedure as a standard  test are analyzed  and compared.   The re-
port will provide data for decision makers  of both government and  industry
alike contemplating  residue leachate  control  from industrial sludge
impoundment/municipal  landfill  co-disposal  operations.
David G. Stephan                        Francis  T.  Mayo
Director                                Director
Industrial  Environmental                 Municipal  Environmental
Research Laboratory                     Research Laboratory
                                      m

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                                  ABSTRACT
      A comparison of three leaching tests was performed with thirteen indus-
trial wastes to evaluate the potential of each test for use as a standard
leaching test procedure.  Such a procedure could be used to assess the leach-
ing characteristics of industrial wastes for land disposal.  The study was
done in conjunction with a background study on the development of a standard
leaching test.  The advantages and disadvantages of each test based on the
leaching characteristics of the thirteen wastes and the usefulness of each
procedure as a standard test are analyzed and compared.  Finally, comments
are provided on the need for careful interpretation of test results.

      This report was submitted in partial fulfillment of Grant No.
R-804773-01 by the Department of Civil and Environmental Engineering, Univer-
sity of Wisconsin-Madis.on.  The work was completed July 1978.
                                      IV

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                                 CONTENTS

Foreword .    .      	                .        .    -    i i 1

Abstract .  .        	              .               iv

Figures and Tables	      .        .             vi

     1.  Introduction    ...        .                .....      1

     2.  Summary and Conclusions        .                                    2

     3.  Experimental Procedures  .....                          7

             Leaching tests  used                                            7

             Wastes used and sample preparation                             7

             Release calculations  .      .  .    .      	       10

     4.  Test Comparison .                                          .  .     11

             Leachate composition                      ....         11

             Solid-liquid ratio   .                        .    .             16

             Number of elutions       .      .              ...             18

             Agitation technique  and  surface
               area of contact          	          .    .             19

             Additional  test comparisons    .          .        ....       22

References  .  .          ......                        .  .           23

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                                  FIGURES

Number                                                                 Page

  1   Cu concentration and release from a
                     sludge in test leachates  ............   15
  2   Variation in Na and K concentration and release
          from an ink and paint waste with solid-
          liquid ratio, using a distilled water
          leachate ........................   17

  3   Napthalene concentration and release from
          a coal tar waste in test leachates .............   20

  4   Na concentration and release from a
          CuO-Na2S04 sludge in test leachates  ............   21


                                  TABLES

Number                                                                 Page

  1    Some features of an ideal standard leaching test  .......    2

  2   Abilities and limitations of each test in
          comparison to an ideal  test  ................    3

  3   A summary of the leaching tests used in
          the test comparison  ....................    8

  4   Wastes used in the test comparison ...............    9

  5   A summary of test comparison results for
          selected parameters from selected wastes  ..........   12

  6   The number of times each test leaching
          solution gave the highest concentration
          of an inorganic parameter from a waste  for the
          different test leachates ..................   13
  7   Number of times acid or h^O leaching  solutions  gave
          highest concentrations  or release of  an  inorganic
          parameter from a waste  for parameters measured in
          both acid and t^O leachates  ................   14

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                                 SECTION 1

                                INTRODUCTION


      Developing awareness of the potential  of landfilled industrial  wastes to
pollute groundwater has led to an interest in a standardized test to  discern
the relative leaching potential  of a waste.   A background study on such a test
has been done by the authors for the U.S.  Environmental  Protection Agency (EPA)
{!).  During this background study a leaching test was developed, called the
SLT.  In order to evaluate the SLT, and other leaching tests which might be
used as the standard test, a comparison of three leaching tests was made by
running the tests on a wide variety of industrial  wastes and comparing the
relative ease, practicality and amount of information obtained in each of the
tests.  The results of the test comparison  are given in  this report.   The test
comparison also serves as a practical  evaluation of the  SLT.

      This report constitutes an Executive  Summary of the complete report of
the study as submitted to EPA (2).

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                                  SECTION  2

                          SUMMARY AND CONCLUSIONS


      Certain features of an  ideal standard leaching test following the
concepts discussed  in Section 4 are given  in Table 1.  An ideal leach-
ing test is defined herein as a standardized procedure which works on all
wastes and is able to predict quickly and with accuracy the potential water
quality degradation within a  landfill represented by the landfill  disposal  of
a particular waste.  It does  not evaluate any changes in leachate quality
arising from passage through  soils or dilution.  The major abilities and
limitations of each test used in this study with regard to these features are
given in Table 2.  Column tests are not included in the concept of an ideal
leaching test because of the  difficulty of using a column test on a wide
variety of wastes.


         TABLE 1.  SOME FEATURES OF AN IDEAL STANDARD LEACHING TEST*
1.    Use of leaching media corresponding to liquids likely to be in contact
      with the waste in the landfill (such as use of both an acid synthetic
      municipal landfill leachate and distilled water leaching solutions for
      modeling leaching in actively decomposing and stabilized municipal
      landfills, respectively).

2.    Incorporates procedures to indicate both concentration and release of
      parameters likely to be leached from a waste.

3.    Use of multiple elutions so secondary effects can be observed.

4.    Use of an effective agitation procedure which does not unnaturally or
      unnecessarily abrade waste particles.

5.    Use of a solid/liquid ratio high enough to minimize analytical and
      sampling errors, yet low enough to allow rapid determination of crit-
      ical concentration and release information for most parameters.

6.    Use of convenient, yet justifiable, elution times and numbers of elu-
      tions.


      *It is assumed that any useable test would incorporate sampling proce-
dures and sufficient replicates to gain statistical reliability.

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             TABLE 2.   ABILITIES AND LIMITATIONS OF EACH TEST IN

                        COMPARISON TO AN IDEAL TEST*
SLT

  Positive aspects:

      1.   Use of two separate  procedures  to  allow prediction  of both  concen-
          tration and release  of parameters  from waste.

      2.   Flexibility of leaching media selection such  as  the use  of  both
          acid synthetic municipal  landfill  leachate  and distilled water as
          leaching solutions to  model  co-disposal  with  muncipal  solid waste.


      3.   Use of an  effective, yet  gentle, agitation  technique.

      4.   Use of multiple elutions.

      5.   Use of an  intermediate solid/liquid  ratio which  lessens  the chance
          of analytical  errors of the  Minn,  test while  generally allowing  more
          rapid evaluation of  release  characteristics than  does  the IUCS test.

      6.   Incorporates procedures which allowed  its direct  use on  all  the
          wastes tested in this  study.


  Limitations:

      1.   Use of an  oxygen sensitive leachate, required for proper modeling
          of leachate generated  in  actively  decomposing municipal  solid  waste
          landfills.

      2.   The laboratory procedures and the  amount of information  obtained,
          especially if both concentration and release  results are desired,
          require more laboratory effort  and interpretive  care.

IUCS TEST

  Positive aspects:

      1.   Use of a generally effective agitation technique.

      2.   Use of multiple elutions.

      3.   Use of a high solid/liquid ratio gives relatively high concentra-
          tions of many parameters.

                       —                                      (continued)
      *i .e.,  Table  1

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                            TABLE 2 (continued)

      4.  Use of a relatively straightforward laboratory procedure.

  Limitations:

      1.  Use of only a distilled water leachate.

      2.  Lack of a procedure to evaluate the max-imum concentration of a
          parameter in leachate.

      3.  Use of an elution time and number such that work needs to be con-
          tinued over weekends.

      4.  Required adaptations on a waste by waste basis to allow some wastes
          to be tested.

      5.  The fewer numerical results require more careful interpretation and
          extrapolation of data than the SLT to apply the results to actual
          landfill situations.


MINNESOTA TEST

  Positive aspects:

      1.  Use of both acid and distilled water leachates.

      2.  Simple and rapid to perform.


  Limitations:

      1.  Acetate buffer models only one aspect of municipal  solid waste
          leachate affecting its leaching aggressiveness.

      2.  Low solid/liquid ratio emphasizes subsampling, weighing, and
          analytical errors.

      3.  Use of only one elution gives much less information than either of
          the other two tests.  No information is provided regarding the
          approach to stable results, the rate at which such  stability is
          reached, or possible secondary effects.

      4.  Agitation technique allows significant concentration gradients in
          the bulk solution, slowing the time needed to approach equilibrium
          and reducing the reproducibility of the results.

      5.  Required adaptations on a waste by waste basis to allow some wastes
          to be tested.

                                                        (continued)

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                            TABLE 2 (concluded)


      6.  Neither concentration nor release information can be obtained with
          confidence because it is not known how close the results are, after
          one elution, to maximum values attainable or to practical values
          reached in actual landfills.  Application of test results to actual
          landfills is difficult to justify.
      A number of different tests could be designed which meet the criteria
of Table 1 and, yet, have considerable differences between them.   Thus, once
a standard leaching test has been designed, interpretation of the test
results becomes a crucial factor in determining the applicability of the test.
A standard leaching test provides a reproducible set of numbers that are a
function of the interaction of a waste with a specific leaching solution
under a specific set of conditions.  It is up to the decision maker to evalu-
ate those numbers and make a prediction regarding the behavior of the waste
in a landfill.  Unfortunately, the multiplicity of factors affecting the
wastes' leaching characteristics, both in the test and in the landfill, and
the variability of landfill conditions, dictate that interpretation be done
with care and with consideration of the waste and landfill characteristics.
Tests results should not be interpreted rigidly; i.e., a certain  concentra-
tion of a given parameter in the test leachate should not be taken to indicate
automatically that the waste is hazardous in the landfill.  Rather, consider-
ation should be given to such factors as the amount of waste to be disposed,
the annual net infiltration of water or movement of groundwater through the
landfill, the factors affecting the leaching of the waste (as far as can be
determined from the test results), possible waste-leachate interactions, and
the fate of the landfill leachate after it leaves the waste and passes through
additional wastes or soil.

      As an example of the need for careful interpretation, consider the
distilled water leachates from the CuO-Na2S04 sludge.  These leachates con-
tained low concentrations of copper (<1 mg/1), yet, very high concentrations
of Na (~10,000 mg/1 in the SLT Elution 1 leachates).   With regard to Na, the
leachate is probably not very hazardous, at least no more hazardous than sea
water which has approximately the same Na concentration.   Yet, in a landfill
or in the soil underneath, the high ionic strength could solubilize potentially
hazardous trace metals through ion exchange mechanisms.   Thus, the leachate
itself may not be hazardous, but it may solubilize hazardous materials in
landfill environments.  Likewise, several wastes released large amounts of
unidentified organic compounds, as evidenced by the very high COD values in
the distilled water leachates.  The potential hazard of these wastes may not
come from the organic compounds released by the waste, if these are not
hazardous, but from the ability of the released organics to solubilize other-
wise insoluble hazardous compounds such as PCBs, chlorinated organic pesti-
cides,  or heavy metals.  On the other hand, a waste may release small amounts
of hazardous materials which will most likely be removed from the leachate
by passage through the soil under the landfill.  The waste might appear to be

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hazardous due to the release of this material in a leaching test, while in
the landfill it would actually be of no practical concern.  Several  wastes
which released trace metals in low concentrations might fall into this cate-
gory.  It should be noted that leaching modeled by the test in one or two days
may simulate years of leaching in the field.  During this time, bacteria may
convert hazardous compounds into innocuous ones, or vice versa, or they may
completely alter the leaching characteristics of a waste through their action
on the waste matrix.

      When interpreting test results, it is important to consider the physical
condition of the landfilled waste.  For example, a waste which is landfilled
in large stable chunks or with a stable impervious coating would most likely
behave far differently in a landfill than in a test in which it were ground.
The test results need to be interpreted with regard to particle surface area
both in the test and in the landfill and in light of the .stability of the
chunks of waste or coatings on the waste in the landfill..

      An evaluation of the hazardous nature of a waste must include an evalu-
ation of the landfill environment.  A waste's hazardous nature is a situation
specific characteristic.  A waste may be hazardous to an organism under one
set of environmental conditions, yet, completely innocuous under a different
set of conditions.  Furthermore, its hazard may be organism specific; i.e.,
it may be hazardous to one organism and not to another under the same set of
conditions.  Thus, a determination of the hazardous nature of a waste must
include an evaluation of its hazardousness to specific organisms under spe-
cific conditions.

      The limitations of a standard leaching test and the care needed in in-
terpreting the results do not mean that a standard test is not worth develop-
ing and using.  A standard test should provide a rapid evaluation of the param-
eters that are likely to be leached from a waste, and an indication of their
maximum concentrations in the leachate and the total amount to be released
per unit weight of waste.  That the test is not perfect in predicting the
long term leaching pattern of a waste or the precise concentration of a par-
ticular parameter in a particular landfill, means that the test results need
to be interpreted with care to avoid unnecessary expenditures for control of
wastes that are not actually hazardous in a particular landfill, or to avoid
unexpected environmental degradation from improper land disposal of a waste.

      In summary, of the three tests compared in this study, the SLT gave the
most information in the shortest amount of time.  The IUCS test could be
improved if several modifications were incorporated, such as use of an acidic
synthetic municipal landfill leachate when co-disposal of the waste being
tested with municipal solid waste is possible, and if a procedure for measur-
ing maximum concentration were added.  The Minn, test would require several
modifications in order to be a widely applicable standard test.

      Whatever standard test is used, interpretation of test results is the
crucial factor in determining the test's ultimate value in predicting whether
a waste is hazardous when placed in a landfill.  Virtually any leaching test
which is properly interpreted would be more useful in making such a predic-
tion than would be a well designed leaching test which is poorly interpreted.

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                                 SECTION 3

                          EXPERIMENTAL PROCEDURES
LEACHING TESTS USED

      The two tests used in addition to the SLT were selected by EPA as being
among the best tests currently available and as having some variety in the
test conditions.   The tests used were the SLT,  an IU Conversion System modi-
fied 48-hour shake test (the IUCS test) and a test developed by the Minnesota
Pollution Control Agency (the Minn.  test).   There are several IUCS shake tests
available, so particular care should be taken to specify the test conditions
when discussing the test.   A summary and comparison of the test conditions is
given in Table 3.  Note that the IUCS test uses fresh leaching media for each
elution, as does  the SLT test procedure R (see  note in Table 3).

      In addition to the tests mentioned above, a municipal  leachate was used
as a leaching medium, using a modified SLT procedure R.   The difficulty in
working with highly air sensitive real leachate necessitated the modifications.
The purpose of the real leachate test (RLT) was not to verify the accuracy of
the synthetic leachate used in the SLT, as might be supposed, but rather to
obtain an idea of the leaching ability of a real leachate sample.  The leach-
ate was not as aggressive  as the leachate upon  which the synthetic leachate
was modeled, and  so cannot be used as a verification of the synthetic leachate.


WASTES USED AND SAMPLE PREPARATION

      Fourteen wastes were used in the test comparison.   The wastes and the
tests they were used in are listed in Table 4.   Since the intent of the com-
parison was to evaluate the tests themselves, the sample preparation procedure
was kept the same for all  tests.  This preparation included a solid/liquid
separation procedure that  is recommended for sample preparation in the SLT
background study.  This technique is not included in either the IUCS or Minn-
tests.  Both of these tests, however, were designed for solid or semi-sol id
wastes rather than for predominantly liquid wastes.  As many of the wastes
used in the test  comparison were predominantly  liquid, the designers of both
the IUCS and Minn, tests were asked how to prepare predominantly liquid wastes
for their tests.   Both agreed that a solid/liquid separation might be one
approach to sample preparation, although both emphasized that their tests were
not designed for such wastes, and that a solid/liquid separation might not be
the approach they would use to prepare predominantly liquid wastes for their
tests.

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TABLE 3.  A SUMMARY OF THE LEACHING TESTS USED IN THE TEST COMPARISON
                       SLT
                          IUCS Test
             Minnesota Test
Leaching
  Solution
 Solid/Liquid
   Ratio
Synthetic Leachate'
    1:10  (Proc.  R)
   Varied (Proc.  C)
1:4
             Acetate  Buffer"1

                 H20§
1:40
Time per
Elution
Number of
Elutions
Temperature
Shaking
Technique
24 hrs
3 or more
Room
Slow Tumbling
(rotating)
48 hrs
5
Room
Back and
Forth Shaking
(reciprocal )
24 hrs
1
Room
1 min. shake,
24 hr rest
(separatory funnel )
      *Two procedures used,  in one of which the solid-linuiH  ratio  is
 varied,  replacing the waste with fresh waste in successive elutions
 (C),  while in the other it  is kept constant, replacing the leaching
 media in successive elutions (R), maximizing concentration  (C)  and
 release  (R),  respectively.

       A  synthetic municipal landfill leachate, with a pH of  4.5 and
 composed as follows:

                        0.15M  Acetic Acid
                        0.15M  Sodium Acetate
                        0.050M Glycine
                        0.008M Pyrogallol
                        0.024M Ferrous Sulfate

      ^pH of 4.5.

      §Distilled,  deionized  water used.
                                     8

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TABLE 4.   WASTES USED IN THE TEST COMPARISON

1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
Waste Waste Abbreviation
Adhesive Waste #1
Ink & Paint Waste I.P.W.
Coal Tar Waste
Health and Beauty u 0 r
r> 1 1 j. n.o.u.
Care Waste
Food Grade Waste
Adhesive Waste #6
Petrochemical
Industry-Water/ Petrochemical Sludge
Oil Sludge
Grain Process-
ing Lipids and Grain Fats
Fats
Food Wastes, Clay
Marble Wash
Copper Oxide-
S±te CuO-Na2S04 Sludge
Sludge
Electroplating Fpc-
Sludge
Wastewater Treat- WT<.
ment Sludge ^
Papermill Sludge, pMC. rnn
Test Used in
SLT,
STL,
SLT,
SLT,
SLT,
SLT,
SLT,
SLT,
SLT,
SLT,
SLT,
SLT,
SLT,
SLT
Minn,
Minn,
Minn,
Minn,
Minn,
Minn,
Minn,
Minn,
Minn,
Minn,
Minn,
Mi nn ,
Minn,

IUCS
IUCS
IUCS
IUCS
IUCS
IUCS
IUCS
IUCS
IUCS
IUCS
IUCS RLT
IUCS RLT
RLT


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RELEASE CALCULATIONS

      The release of a parameter per unit mass waste for each of the tests
was calculated using the equation given below:


                        N

                       2~^ (conc(i), mg/L)(leachate volume, mL)(l L/1000 mL)


   Releaseelution(i)          (dry weight of solid in test, g )(1 kg/lOOOg)


where i is the elution number and N the total number of elutions.  Leachate
volume and dry weight of solid is constant for each test, except for SLT pro-
cedure C.  Since the purpose of procedure C is to evaluate maximum concentra-
tion, release using this procedure was not calculated.  Except for unusual
release patterns, release  in procedure R will be greater than or equal to that
in procedure C.
                                       10

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                                 SECTION 4

                              TEST COMPARISON


      In order to compare results of the different test procedures and leach-
ing media, a comparison can be made of the  concentration in the different test
leachates of a single parameter leached from a waste.   This has been done in
Table 5 for selected parameters from selected wastes.   Such a single parameter
comparison does little good in understanding the relative aggressiveness of
the tests unless the factors affecting the  parameter concentration in the
leachates are known.  However, the  relative aggressiveness of the tests can
be analyzed by comparing the number of times each test gave the highest con-
centration (or release) of a parameter for  all  the parameters analyzed through-
out the test comparison.  This has  been done for parameter concentration in
Table 6.  As can be seen for the parameters measured,  the SLT gave the high-
est concentration much more frequently than the other tests.   Table 7 shows a
similar comparison for acid and water leachates, comparing only parameters
that were measured in both.  It is  obvious  from the table that acid leachates
are much more aggressive than distilled water leachates.

      A more complete comparison of the tests entails  an analysis of the
effects of the differences between  the tests on the test results, and the
importance of these differences for interpreting the test results.   The tests
were compared as whole units with several factors differing between them.
Therefore, it is not possible with  any degree of certainty to isolate one
factor and explain differences between the  tests as based on  that single fac-
tor.  Rather, one can only say that a given factor varied between tests and
that it seems reasonable to ascribe a given difference in the test results to
this factor, as in the following sections.


LEACHATE COMPOSITION

      The profound effect of leaching solution composition on the materials
and concentrations leached from a waste is  shown with  several wastes used in
the test comparison, most notably the CuO-Na2S04 sludge.   Using the CuO-Na2S04
sludge as an example, acidic leachates—the synthetic  leachate and the acetate
buffer—leached potentially hazardous trace metals in  significant concentra-
tions as shown in Figure 1.  These  metals were either below detection limits
or leached in very low concentrations in the water leachates.  The copper
concentrations in the acidic leachates were four orders of magnitude (10,000
times) higher than the copper concentrations in the water leachates.  Since
landfills produce acidic leachates  comparable with respect to both pH and
buffering capacities to the synthetic leachate used in the tests during part

                                       11

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              TABLE 5.   A  SUMMARY OF TEST  COMPARISON  RESULTS



                FOR SELECTED PARAMETERS FROM SELECTED  WASTES
Concentration, no/L
Waste
Parar«ter S

.L.*
Proc C
Ink 1 Paint Waste:
Na
K
V.g
Zn
Pb
Cu
Cd
Cyclohexanone
Napthalene
COO
Coal Tar Waste:
Napthalene
Phenol
Cresol
Quinoline
COO
Health J Beauty Care
Zn
Cd
ft
Cu

COO
Food Intfjstry,
COD
Marble Wash:
fb
CK>










12.7
493
138
307
Uaste:
25.0
0.92
5.60
0 86

1.8
0.95
0.60
SLT
S.L.* H2
-------
TABLE 6.   THE NUMBER OF TIMES EACH TEST LEACHING SOLUTION GAVE THE
 HIGHEST  CONCENTRATION OF AN INORGANIC PARAMETER FROM A WASTE FOR
                  THE DIFFERENT TEST LEACHATES

Na
K
Mg
Fe
Zn
Pb
Cu
Cd
COD
Total
Number
Total %
Total %
for Each
Test
SLT
Proc C Proc R Minn IUCS
Hr\ ci u n ci A/~ot" u r\ u n
oU oi_ hoU oL HLC L n^u n«u
*
8 -- -- - 4
1 10 1
17 11
1 -- 1 1
6 52
1 1 4
1 2 1
2
4
16 24 1 11 8 0 6
60.6 18.2 12.0 0 9
SLT Minn IUCS
79% 12% 9%
    *Not measured.
                                13

-------
TABLE 7.  NUMBER OF TIMES ACID OR H20 LEACHING SOLUTIONS GAVE HIGHEST
CONCENTRATIONS  OR  RELEASE  OF  AN  INORGANIC  PARAMETER FROM A WASTE FOR
        PARAMETERS MEASURED IN BOTH ACID AND H20 LEACHATES
SLT
Acid H20
Minn
Acid H20
IUCS Total
H20 Acid hLU
TOTAL TESTS
          Number of Times GJving Maximum Concentration

K     10     1                      1        10       2          12
Mg     8     1        1                       9       1          10
Zn    11              2                      13       0          13
Pb     2              4                       606
Cu     2     1                      122           4
Cd     1                                     J_       0          J_
                                             41       5          46*
             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^
46
0
1
0
0
1
0
2
12
11
12
6
4
_3^
48*
      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.
                                   14

-------
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        A   REAL  LEACHATE
        NOTE:  Cu concentrations in all  distilled water leachates were less
              than  0.6ppm.
        Figure I.   Cu concentration and release from a CuO-Na?SO.
                  sludge in  test leachates.

-------
of their life span, and would leach Cu from the CuO-Na2S04 sludge, the need
for such a leachate in the leaching test is apparent.  The comparison of the
synthetic leachate and actual leachate is indicated by the results of the SLT
leaching test using municipal landfill leachate.  Although not as acidic as
either of the acid leachates, the municipal landfill leachate still leached
much higher concentrations of copper than were obtained using distilled water
as the leachate.

      The synthetic leachate gives a more accurate view than does the acetate
buffer of the leaching that would occur in a young municipal landfill.  This
is because it models more aspects of municipal leachate than does the acetate
buffer, which models only pH.  The synthetic leachate models an anaerobic
municipal leachate.  Being anaerobic, it is air sensitive and requires careful
handling to avoid changes brought about by air contact.  The most readily
observed change  is the formation of an iron precipitate which forms an oxida-
tion.  Precipitation introduces the possibility of loss from solution of mate-
rials by either  occlusion in or adsorption on the precipitate.  Thus, simple
air contact of the synthetic leachate may cause inaccurate results.  An alter-
native, an aerobic synthetic leachate, has been developed.  This leachate
avoids the oxidation-precipitation problem, but does so at the cost of not
modeling the redox potential of real leachate as completely as does the
anaerobic synthetic leachate.

      The anaerobic synthetic leachate is designed to model the leaching
environment found in actively decomposing municipal landfills.  Since many
wastes will be landfilled by themselves or with other industrial wastes, other
leaching solutions are needed to model the leaching environment found in those
landfills.  For  such situations, the SLT procedure recommends use of other
leaching media such as distilled water or that obtained by prior contact of
distilled water  with the other wastes in question, or the media may be spe-
cially formulated to relate to the leachate expected from the other wastes.
All three tests  use a distilled water leachate which would be more realistic
than synthetic municipal landfill leachate in many landfill situations.


SOLID-LIQUID RATIO

      A direct dependence of concentration on solid/liquid ratio was frequently
seen with very soluble parameters, such as Na and K.  Good examples of this
behavior are found in the Na and K data derived from leaching ink and paint
waste.  A graph  of the Na and K concentrations in the first H20 leaching from
ink and paint waste versus the amount of solid present per 100 ml leachate
(Figure 2) shows that the Na or K concentrations fall nearly on a straight
line.  This indicates that the concentration in solution is directly dependent
on the amount of solid present for these parameters.

      At the other extreme is a parameter whose concentrations are controlled
strictly by solubility equilibrium.  In this case, the concentration in solu-
tion would appear to be independent of the amount of solid present and would
be the same in all tests.  Such a situation has been ecnountered with the
wastes studied.   For most parameters, concentration will probably be controlled
                                      16

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        O  SLT,

        O  IUCS,

        V  MINNESOTA

  Figure 2.  Variation  in  Na and K concentration and release from
           an ink and paint waste with solid-liquid ratio (in
           grams waste per 100 ml leaching media), using a dis-
           tilled water  leachate.
                              17

-------
by a number of competing factors—amount present, solubility, sorption or
desorption, etc.—and the effect of solid/liquid ratio on the concentration
will be more complicated than simple solubility relationships would suggest.
However, several practical considerations enter into the choice of a solid/
liquid ratio for a reliable standard test.  A very low ratio, such as that
used in the Minn, test, requires small amounts of solid and generally produces
low concentrations of eluted parameters.  This emphasizes analytical and sam-
pling errors.  Also, a very low solid/liquid ratio models a much longer leach-
ing time in a landfill than does a higher ratio.  While this might at first
appear to be an advantage, the accuracy with which a short test models long-
term leaching in a landfill probably decreases as the landfill time span
modeled gets longer.  Thus, a test with a very low solid/liquid ratio is less
accurate for both modeling reasons as well as analytical ones in comparison
with tests using higher ratios.  On the other hand, a test with a very high
solid/liquid ratio, while decreasing subsampling and analytical errors,
requires more elutions to deplete a partially soluble parameter in a waste in
order to determine maximum release than does a test with a lower ratio.  A
solid/liquid ratio should, therefore, be selected between these two extremes.
Experiments conducted during development of the SLT (1) suggest that the 1 to
40 ratio used in the Minn, test is rather low and that both the 1:10 and 1:4
ratios used in the SLT and IUCS tests, respectively, are reasonable.  Either
ratio could be used in a reliable standard test.

      It is important to note how the weight of waste material is measured
when calculating the solid/liquid ratio.  Dry weight, which is commonly used,
can present analytical difficulties for wastes containing volatile or semi-
volatile components other than water.  Experiments with a variety of wastes
during development of the SLT suggested the use of drying at 105°C in a forced
air convection oven for 24 hours as a reasonable procedure to define dry
weight (1).

      The choice of a solid/liquid ratio generally is not directly based on
landfill conditions (unless calculated from waste and rainfall conditions)
and, within a range between the extremes discussed above, is, therefore,
arbitrary.


NUMBER OF ELUTIONS

      Both the SLT and IUCS tests use multiple elutions.  Far more information
can be obtained from multiple elutions than from a single elution as used in
the Minn. test.  The IUCS test uses five elutions, while the SLT uses three
(unless the pH in the synthetic leachate samples has not returned to below
5.0, in which case additional elutions are suggested until the pH does return
to 5.0 (1)).  The extra elutions in the IUCS test provide more information
than the three elutions in the SLT; however, they also require more work.  A
compromise needs to be made between the value of added information obtained.
from the extra elutions and the added work involved in obtaining it.

      Multiple elutions provide information about the kinetics of release;
for example, whether the release of a particular parameter is controlled by
solubility or by the release of another parameter (i.e., matrix or surface

                                      18

-------
decomposition triggering subsequent release of parameters held in the matrix
within the waste particles).   With one elution, some species may not be
observed leaching from a waste when,  in reality, they release in significant
amounts in later elutions.   On the other hand, the last elution generally
yields successively less information  as more elutions are specified.  Thus,
the twentieth elution in a  twenty-elution test is likely to yield substan-
tially less information than  the third elution in a three-elution test.  For
some wastes, one elution will  give all the information obtainable; some wastes
will require three elutions,  some five, a few wastes, perhaps, fifty.   There
is no way of knowing the required number of elutions for a given waste without
running extensive tests to  determine  when some relative equilibration is
reached.  This, obviously,  is  contrary to the concept of a standard test.
Experiments performed with  a  variety  of wastes in developing the SLT indicated
that more elutions than three  generally provided little or no additional
information (1).  This was  also found to be true in the present study.

      Another factor in the selection of the number of elutions for a  stand-
ard leaching test is simply convenience.  When it is technically feasible,
the number of elutions chosen  should  be convenient for laboratory personnel.
The IUCS test is more inconvenient and/or expensive than the other tests in
that it requires working on weekends  to perform five 48-hour elutions.

      It is concluded that  selection  of the number of elutions should  be based
on the number of elutions found useful for a variety of extensively tested
wastes and on convenience.  The author's experience is that three is generally
sufficient, but if some key parameter with a particular waste suggests  addi-
tional elutions (e.g., pH remaining above 5 using the synthetic leachate),
additional elutions should  be  run.
AGITATION TECHNIQUE AND SURFACE AREA OF CONTACT

      The SLT and the IUCS tests had generally effective agitation  techniques
in that little particle abrasion was observed and particle and  leaching media
movement was sufficient to avoid visually obvious concentration profiles in
the media.  The Minn, test developed pronounced concentration  differences
which were observable between the liquid located near the waste particles and
that located away from the particles when colored components were being
leached.  These concentration differences are not surprising,  since the waste
is not agitated for 24 hours following the initial  shaking.

      For two wastes, namely, the coal tar waste and the CuO-Na2S04 waste, the
SLT agitation method in itself appeared to be one reason for the higher
release with the SLT test than with the IUCS test.   In the SLT agitation pro-
cedure, the waste is always gently tumbling through the leachate.  This
exposes more surface area of the waste to leachate contact.  The IUCS test
agitation procedure did not provide such particle agitation of the waste,
resulting in approximately the same waste surface being in contact with the
leachate.  With coal tar waste, the concentration of napthalene was higher
in the SLT H20 leachates than in the IUCS H20 leachates (Figure 3).  Given
the physical nature of coal tar, it is reasonable to ascribe  the higher con-
                                      19

-------
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       D  IUCS-H20
                                              MINN-ACETATE

                                              MINN-H20
       Figure 3.  Napthalene concentration and  release from a coal tar
                waste in test leachates.
                               20

-------
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MINN -ACETATE BUFFER

MINN - H20

REAL LEACHATE
Figure 4.  Na concentration and release from a CuO-Na?SO.
         sludge in  test leachates.
                          21

-------
centrations to the greater surface area in contact with the leaciiate.  Coal
tar is impervious to water and viscous enough to inhibit internal diffusion.
Thus, for unsaturated parameters, the concentration in leachate will depend
on the surface area of contact with the waste.  Another probable example of
the effects of agitation on release can be seen in the Na release from the
CuO-Na2S04 sludge (Figure 4).  A comparison of the Na release in the SLT and
IUCS tests using H20 as the leaching media shows a more rapid drop off in
release in the IUCS test such that the fifth elution, for example, provided
little additional release beyond that of the fourth elution.  The SLT data
indicate that the Na is continuing to be released in the later elutions.  It
appears that the waste in the IUCS test formed a thick layer in the test ves-
sel and was subsequently released slowly by diffusion.  In the SLT, the
tumbling agitation constantly mixed the waste and leachate in order to mini-
mize the amount of stagnant interstitial water.  Thus, the more complete mix-
ing in the SLT promoted continued dissolution of very soluble components.


ADDITIONAL TEST COMPARISONS

      The SLT uses either or both of two elution procedures:  one in which
fresh waste is contacted with leachate fromthe previous elution (procedure C),
and one in which fresh leachate is contacted with a previously eluted waste
(procedure R).  The IUCS test uses only a procedure similar to procedure R;
whereas, the Minn, test uses only one elution.  Procedure C gives an indica-
tion of what will happen to a given parameter as the leachate passes through
a large volume of waste; i.e., the procedure will give results which approxi-
mate or approach saturated conditions.  As landfills will generally have very
high solid/liquid ratios, at least temporarily, and the leachates will often
be saturated, this information can be very useful.  On the other hand, an
estimation of the total amount of a parameter which may potentially be
released to the environment requires information about the maximum release
under landfill conditions per unit mass of waste.  The two procedures in the
SLT allow an estimation of both maximum concentration and  maximum release.
Neither of the other tests, nor any others known to the authors, allow both
estimations.  The IUCS test gives an estimate of maximum release, since it
also involves multiple Teachings of the same waste sample.

      The Minn, test results cannot be used by themselves to provide with any
degree of certainty either maximum concentration or release information.  The
results may have practical value bv being comparable to results from some full
scale landfills, but there is no way of knowning this in advance without hav-
ing an extensive data base from monitoring actual landfills.

      The effects of two test conditions, namely, time per elution and tem-
perature, could not be analyzed from the test results.  All the tests were
run at the same temperature (ambient or 20°C).  The IUCS test uses a 48-hour
elution time, while both the Minn, and SLT tests use a 24-hour elution time.
The effect of elution time cannot be separated from other variables in compar-
ing the three tests.
                                      22

-------
                                 REFERENCES

1.     Ham, R.K.,  M.A.  Anderson,  R.  Stegmann,  and R.  Stanforth.   Background
      Study on the Development of a Standard  Leaching Test.   Final  Report on
      EPA Grant  R-804773-01,  submitted to EPA August, 1978.

2.     Ham, R.K.,  M.A.  Anderson,  R.  Stegmann,  and R.  Stanforth.   Comparison of
      Three Waste Leaching Tests.   Final  Report on the extension of EPA Grant
      R-804773-01, submitted  to  EPA October,  1978.
                                      23

-------
                                   TECHNICAL REPORT DATA
                            (Please read Instructions nn thi rt < me hifon1 l
1 REPORT NO.
 EPA-600/8-79-001
                              2.
                                                           3. RECIPIENT'S ACCESSION NO.
4. TITLE ANOSUBTITLE
                                                           5. REPORT DATE
 COMPARISON  OF THREE WASTE LEACHING  TESTS
 Executive Summary
                                                           6. PERFORMING ORGANIZATION CODE
                                                            May  1979  (Issuing Date)
7 AUTHOR(S)
 Robert  K.  Ham,  Marc A. Anderson,  Rainer Stegmann,
 and Robert Stanforth
                                                           8 PERFORMING ORGANIZATION REPORT NO.
9 PERFORMING ORGANIZATION NAME AND ADDRESS
 Department  of  Civil  and Environmental  Engineering
 University  of  Wisconsin-Madison
 Madison, Wisconsin  53706
                                                            10. PROGRAM ELEMENT NO.

                                                             1DC818,  SOS 1,  Task 38A
                                                            11. CONTRACT/GRANT NO
                                                            Grant  No.  R-804773-01
12. SPONSORING AGENCY NAME AND ADDRESS
 Municipal  Environmental Research  Laboratory—Gin. ,OH
 Office  of  Research and Development
 U.S.  Environmental Protection  Agency
 Cincinnati,  Ohio  45268
                                                            13. TYPE OF REPORT AND PERIOD COVERED
                                                           Final Report,Executive Summary
                                                            14. SPONSORING AGENCY CODE
                                                            EPA/600/14
15. SUPPLEMENTARY NOTES
 See also  main report "Comparison  of Three Waste Leaching Test,"  EPA-600/2-79-071
 Project Officer:  Donald Sanning   513/684-7871
16 ABSTRACT
 A comparison of three leaching  tests was performed with  thirteen  industrial  wastes to
 evaluate  the potential of each  test for use as a standard  leaching  test procedure.
 Such  a  procedure would be used  to  assess the leaching characteristics of industrial
 wastes  for land disposal.  The  study was done in conjunction  with a background study
 on the  development of a standard  leaching test.

 The advantages and disadvantages  of each test based on the leaching characteristics
 of the  thirteen wastes and the  usefulness of each procedure as  a  standard test are
 analyzed  and compared.  Finally,  comments are provided on  the need  for careful
 interpretation of test results.
17
                                KEY WORDS AND DOCUMENT ANALYSIS
                  DESCRIPTORS
 Leaching
 Tests
 Methodology
 Selection
 Interpretation
 Assessments
 Evaluation
                                               b. IDENTIFIERS/OPEN ENDED TERMS
                                                Leaching Tests
                                                Industrial Sludges
                                                                         t.  COSATl l-icld/Ciroup
       14B
18 DISTRIBUTION STATEMENT
 Release to  Public
                                              19 SECURITY CLASS (Tliiv Report/

                                                Unclassified
21 NO. OF PAGES

       30
                                              20 SECURITY CLASS /Tins page)
                                                Unclassified
                                                                         22. PRICE
EPA Form 2220-1 (Rev. 4-77)
                                             24
                                                       S. GOVERNMENT PRINTING OFFICE: 1979-657-060/1670 Region No. 5-11

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