United States
                        Environmental Protection
                        Agency
  Municipal Environmental Research
  Laboratory
  Cincinnati OH 45268
                        Research and Development  EPA-600/D-81-104  August 1982
                        ENVIRONMENTAL
                        RESEARCH    BRIEF
                    Stabilization, Testing, and Disposal of
                          Arsenic Containing Wastes

                            Jaret C. Johnson and Robert L. Lancione
                        JBF Scientific Corporation, Wilmington, MA 01887
Commercially  available  treatment  processes
intended to reduce leaching of contaminants from
wastes were evaluated for arsenic-laden industrial
wastes. Three wastes were selected: (1) residues
from the production of arsenical herbicides, (2) filter
cake from the refinement of food-grade phosphoric
acid, and (3) flue, dusts  from nonferrous  metal
smelters. Each  of these wastes was treated with
many treatment (fixation) processes. The processes'
ability to retard the leaching of arsenic was evaluated
through  the results of  laboratory  leaching  tests.
Several processes reduced arsenic leaching rates by
at least four orders of magnitude. Other processes
were much less effective.

Introduction

Arsenic is present in many industrial solid wastes,
and improper disposal of some of these wastes has
caused contamination of some groundwaters. More
properly managed arsenic-bearing wastes have often
been kept in dry storage, which is only a temporary
option. The need for improved methods for managing
arsenic-bearing wastes was the stimulus for this
work.

The passage of the  Resource Conservation and
Recovery Act of 1976 (RCRA, PL 94-580) also added
importance to this work. Rules for implementing this
law have recently been promulgated, and the rule-
making process is continuing to resolve issues  left
uncertain by those rules. In particular, the develop-
ment of rules for Section 3001 of RCRA (identification
and listing of hazardous waste) prompted some of the
work in this project.

Purpose and Scope

This study was done to develop recommendations,
based on laboratory test data, forthe environmentally
safe disposal of arsenic-bearing wastes. The labora-
tory tests were to .evaluate the fixation processes'
ability  to  retard the leaching of arsenic. The major
efforts were to:

 1.  Identify the arsenic-bearing wastes of greatest
    environmental significance.

 2.  Identify new and availablefixation technologies.
    Both  commercially available processes and
    generic methods that might be performed with
    ease and economy by waste generators were
    evaluated. This effort was carefully coordinated
    with experimental work on arsenic-laden flue
    dusts being conducted at the  Montana Tech
    Foundation  Mineral Research Center so that
    duplication would be avoided.

 3.  Test the effectiveness of fixation processes.
    Four tests were performed assessing several
    aspects of leaching potential.

 4.  Evaluate the potential for increased commercial
    use  of arsenic  and its compounds to reduce
    amounts requiring disposal.

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Definitions and Identifications

The terms fixation, immobilization, and stabilization
are used interchangeably throughout this report for
the processes applied to the wastes.

Publicity or endorsement of any specific commercial
processes was not the purpose of this work. The goal
was determining whether any commercial processes
effectively reduced arsenic leaching from each waste
and to what extent. In this way, EPA can use the work
to assess the state of the art and to help develop
regulations.  Therefore, leaching  test  results for
commercial products identified  the  processors by
code letters in all project reports.

Generation and Potential Use of Wastes

The principal domestic sources of industrial wastes
that contain arsenic are nonferrous metal smelters,
chemical  process  industries producing  food-grade
phosphoric  acid  (by  removing  arsenic from the
product),  pesticide  manufacturers,  and veterinary
Pharmaceuticals producers. Of these  sources,  only
the nonferrous metal smelters produce arsenic as a
commodity.

We also acquire a supply of arsenic through importa-
tion.  Although annual  figures of supply  of,  and
demand  for,  arsenic and  its compounds  are  very
erratic, some  generalizations can be made.  During
the 1970's, approximate typical annual figures were
(all data in metric tons of arsenic):
    Imports

    Domestic Production

    (Including net
     transfers to/from
     storage)

          TOTAL SUPPLY

          TOTAL DEMAND
 9,000

19,000
       28,000

       19,000
                 specific uses of the product). Other users are also
                 uncertain, primarily because of workplace exposure
                 regulations. These users include the glass industry
                 and wood preservative manufacture and those using
                 arsenic  as an alloying element in metals or as a
                 component of semiconductors and photovoltaic cells.

                 Three types of arsenic-laden wastes are particularly
                 important: The volume and arsenic concentration of
                 flue  dusts from  the  primary nonferrous smelting
                 industry, filter cake from the purification  of food-
                 grade phosphoric acid, and  salt residues from the
                 manufacture of organic arsenical herbicides. These
                 byproducts of industrial activities vary in the chemical
                 form of arsenic and in the physical-chemical proper-
                 ties of the bulk  matrix.  Testing  of these wastes
                 therefore provided a  range of challenges to the
                 fixation processes.
Effectiveness of Fixation Processes

Fourteen proprietary processes  and nine generic
processes were appliedtothe three types of wastes; a
few of the waste/process combinations were incom-
patible. Most effort was given to  vendor processing
rather  than developing generic  processes.  Three
factors guided this approach: (1) The broad range of
concepts used by commercial or academic process
developers. (2) Development of new approaches is
time-consuming and involves therisk of being unsuc-
cessful.  (3) Vendors  furnished  approximate  cost
estimates that appeared not to be prohibitively high,
so the economic need to develop  "do-it-yourself"
processes for waste generators was not great.

Four kinds  of leaching tests were  applied to each
treated waste. For control and reference, each waste
without treatment and each fixation process reagent
mix without waste was subjected to the same leach-
ing test. These  leaching  tests  demonstrated the
existence of several  processes, both proprietary and
generic, that can significantly reduce the amount of
arsenic  release and the rate of  release relative to
untreated  wastes.  Also  demonstrated  was  the
importance of the type of leaching test on the results.
These figures show that the excess of supply over
demand  is approximately equal  to the  amount of
arsenic imported. If imports were banned, however,
the arsenic disposal problem would not necessarily
be eliminated.

The. primary users of arsenic have  an  uncertain
future. Arsenic-containing pesticide manufacturers,
the  major users, are  under  constant regulatory
pressure regarding workplace exposure to arsenic as
well as maintaining registrations (EPA approval for
                 Shake Tests

                 During the shake test, each material was immersed in
                 distilled water, with gentle agitation to prevent fluid
                 stratification. Every 2 days the water was changed,
                 with an aliquot taken for analysis. Leaching behavior
                 was thus assessed over a period of up to 2 months for
                 each sample. Each test was duplicated, and analytical
                 quality control was achieved through internal checks
                 and more than 200 blind replicate comparisons with
                 an outside laboratory.

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These tests show  commercially available fixation
processes  offer a wide  range of effectiveness in
reducing the  leaching of arsenic from  the  three
wastes. Some processes reduced leaching rates by
more than  four orders of magnitude relative to raw
wastes, and some were less effective. Processes also
vary in their behavior with time:  leaching rates for
some waste/process combinations increased with
time whereas  others decreased. Detailed results of
the shake tests are  provided in a paper prepared for
submittal to a  peer-review journal.

Brief Elutriate  Tests on Crushed Samples

A violent 24-hour shake test with crushed samples
was performed in distilled water. In this test, breaking
the monolithic structures was intended to simulate
physical breakdown in the field.

The  samples  of treated  pesticide manufacturing
waste all released much of their arsenic; the percent
leached from both proprietary and generic samples
ranged  from 28% to 100%.  Arsenic leaching from
treated samples of other wastes was much lower and
more variable  from  process  to  process.  These test
results, viewed as process effectiveness, were quite
different from the  shake test results  on   intact
samples. The  two tests therefore can be used to
provide information about fundamentally different
aspects of leaching  behavior.

Elutriate tests  on samples fixed by generic (nonpro-
prietary) methods in the laboratory suggested that
molten  sulfur, cements,  and materials  containing
sulfhydryl groups have promise as relatively easy-to-
use fixing agents.

Extraction Procedure

This work was conducted while EPA was developing
methods to identify hazardous wastes under Section
3001  of RCRA.  An  early version of the  extraction
procedure (EP) was used in this project in support of
EPA's rulemaking. The version used here called for
sample  crushing, 48-hour exposure to water, main-
tenance of pH near 5.0,  and moderate agitation.
Results were  generally similar to those from the
elutriate test.  Some   samples,  however,   were
adversely affected by the pH control in the EP. Cement
matrices, for example, maintain some arsenic forms
as\ insoluble   primarily  because  of the matrices'
alkalinity. This effect is nullified by the acid additions
in the EP.

Shake 1[est With Landfill Leachates

The shake  tests were repeated. This time two real
landfill leachates collected from municipal landfills in
 Enfield (Connecticut) and Barre (Massachusetts),
 rather than distilled water, were used. Data were of
 limited applicability  because  attempts  to  avoid
 chemical  precipitation in  the water samples after
 filtration were not completely successful. A negative
 bias resulted in the data for arsenic leaching.

 Recommendations

The  following recommendations are presented  in
order of priority:

The present form of the EP should be applied to the
 more  promising  waste/product  combinations
 evaluated  in this project. This test now allows use of
 monolithic structures that survive a compaction test.

 Field  lysimeter tests should  be conducted on fixed
 arsenic-laden wastes to confirm and extend the find-
 ings  of this   laboratory  study.  Stresses  such  as
freeze/thaw,  wet/dry, and hot/cold cycles can thus
 be assessed. Co-disposal with municipal solid waste
 can also be assessed under  field conditions in this
 manner.  Without such  field  data,  EPA cannot
 adequately judge the full-scale use of the waste/
 process combinations assessed in  this laboratory
 study.

A protocol  should  be  designed  and  used that
 eliminates the problem of chemical precipitation in
 shake tests with landfill  leachates.  Other studies
 have  investigated pollutant attenuation with oxygen-
free test conditions, as well as analytical methods for
 leachates.  Some of the techniques used  in those
 studies may be adaptable to  the development of a
 shake  test/sample   processing/sample  analysis
 protocol that accurately simulates anoxic conditions
 in a landfill. For example, shake testing, filtration, and
 sample storage might be done in glove bags with a
 nitrogen or CC"2 atmosphere.

A study should be made of the effect of the OSHA
 standard for arsenic exposure in the workplace on the
 generation of unmarketable arsenic-laden flue dusts.
 Predictions reviewed in  this study suggest that
 markets for arsenic derived from these dusts will
 decline because of industries'  cost to  achieve the
 OSHA standard and  because of some industries'
 discontinued  use of arsenic. Actual developments
 should be followed, not only for EPA to keep abreast of
the problems with arsenic-laden wastes, but also to
 gain  general  insight  into  secondary  effects of one
 agency's  actions (e.g., OSHA) on other agencies'
 responsibilities (e.g., EPA).

The  economic and environmental  implications  of
 arsenic imports should be assessed. Limiting imports
 could  lessen  disposal  problems  because  more
  « U.S. GOVERNMENT PRINTING OFFICE: 1982-559-017/0777

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       domestic arsenic wastes  would be converted to a
       useable commodity. This, however, would adversely
       affect importers and may be politically undesirable as
       a restraint of international trade.  Also,  domestic
       production may be unable to satisfy demand.

       Further development work should be conducted on
       molten  sulfur, cements, and  materials containing
       sulfhydryl groups. Sulfur and cements simply require
       optimization of waste loadings and conducting more
       leaching tests.  Using  sulfhydryl  groups  requires
       selecting materials, optimizing waste loadings,  and
       probably selecting  an encapsulation  system (e.g.,
       cement). These  generic processes may  not yield
       improvements   in  leaching  resistance over
       commercial processes, but they may yield savings in
       cost or provide methods that can be directly used by
       waste generators.

       This Research Brief  describes  work  done  under
       Contract No. 68-03-2503 by JBF Corporation under
       the sponsorship of the U.S. Environmental Protection
       Agency.

       Donald E. Sanning, the EPA Project Officer, is with
       the Municipal Environmental Research Laboratory,
       Cincinnati, OH 45268.
United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
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Fees Paid
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Agency
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Penalty for Private Use $300

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