Engineering Bulletin: Chemical Dehalogenation Treatment: APEG Treatment

&EPA
Office of Emergency and
Remedial Response
Washington, DC 20460
^
Office of *', ~ 'v. /;'
Research and Development
Cincinnati, OH 46268 ,
Superfund
EPA/54Q/2-90VQ15
September 1990
Engineering Bulletin
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Chemical Dehalogenation
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Purpose

Section 121(b) of the Comprehensive Environmental
Response, Compensation, and Liability Act (CERCLA) mandates
the Environmental Protection Agency (EPA) to select remedies
that "utilize permanent solutions and alternative treatment
technologies or resource recovery technologies to the
maximum extent practicable" and to prefer remedial actions
in which treatment "permanently and significantly reduces
the volume, toxicity, or mobility of hazardous substances,
pollutants and contaminants as a principal element." The
Engineering Bulletins are a series of documents that summarize
the latest information available on selected treatment and site
remediation technologies and related issues. They provide
summaries of and references for the latest information to help
remedial project managers, on-scene coordinators, contractors,
and other site cleanup managers understand the type of data
and site characteristics needed to evaluate a technology for
potential applicability to their Superfund or other hazardous
waste site. Those documents that describe individual treatment
technologies focus on remedial investigation scoping needs.
Addenda will be issued periodically to update the original
bulletins.
Abstract

The chemical dehalogenation system discussed in this
report is alkaline metal hydroxide/polyethylene glycol (APEG)
which is applicable to aromatic halogenated compounds.
The metal hydroxide that has been most widely used for this
reagent preparation is potassium hydroxide (KOH) in
conjunction with polyethylene glycol (PEC)[6, p. 461]*
(typically, average molecular weight of 400 Daltons) to form
a polymeric alkoxide referred to as KPEG [16, p. 835]. However,
sodium hydroxide has also been used in the past and most
likely will find increasing use in the future because of patent
applications that have been filed for modification to this
technology. This new approach will expand the technology's
applicability and efficacy and should reduce chemical costs by
facilitating the use of less costly sodium hydroxide [18]. A
variation of this reagent is the use of potassium hydroxide or
sodium hydroxide/tetraethylene glycol, referred to as ATEG,
that is more effective on halogenated aliphatic compounds
[21]. In some KPEG reagent formulations, dimethyl sulfoxide
(DM SO) is added to enhance reaction rate kinetics, presumably
by improving rates of extraction of the haloaromatic
contaminants [19][22].

Previously developed dehalogenation reagents involved
dispersion of metallic sodium in oil or the use of highly
reactive organosodium compounds. The reactivity of metallic
sodium and these other reagents with water presented a
serious limitation to treating many waste matrices; therefore,
these other reagents are not discussed in this bulletin and are
not considered APEG processes [1, p. 1].

The reagent (APEG) dehalogenates the pollutant to form
a glycol ether and/or a hydroxylated compound and an alkali
metal salt, which are water soluble byproducts. This treatment
process chemically converts toxic materials to non-toxic
materials. It is applicable to contaminants in soil [11, p. 1],
sludges, sediments, and oils [2, p. 183]. It is mainly used to
treat halogenated contaminants including polychlorinated
biphenyls (PCBs) [4, p. 137], polychlorinated dibenzo-p-dioxins
(PCDDs) [11, p. 1 ], polychlorinated dibenzofurans (PCDFs),
polychlorinated terphenyls (PCTPs), and some halogenated
pesticides [8, p. 3][14, p. 2]. This technology has been
selected as a component of the remedy for three Superfund
sites. Vendors should be contacted to determine the availability
of a treatment system for use at a particular site. The estimated
costs of treating soils range from $200-$500/ton. This bulletin
provides information on the technology applicability, the types
of residuals resulting from the use of the technology, the
latest performance data, site requirements, the status of the
technology, and where to go for further information.
Technology Applicability

This technology is primarily for treating and destroying
halogenated aromatic contaminants. The matrix can be soils,
sludges, sediments, or oils. If a waste site has contaminants
other than halogenated compounds, other alternatives should
be considered.

The concentrations of PCBs that have been treated are
reported to be as high as 45,000 ppm. Concentrations were
* [reference number, page number]

-------
United States
Environmental Protection
Agency
Office of Emergency and
Remedial Response
Washington, DC 20460
Research and Development
Cincinnati, OH 45268 ,
Superfund
EPA/540/2-90/Q15
September 1980
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oEPA Chemical Dehalogenation
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Purpose

The chemical dehalogenation system discussed in this
report is alkaline metal hydroxide/polyethylene glycol (APEC)
which is applicable to aromatic halogenated compounds.
The metal hydroxide that has been most widely used for this
reagent preparation is potassium hydroxide (KOH) in
conjunction with polyethylene glycol (PEG)[6, p. 461]*
(typically, average molecular weight of 400 Daltons) to form
a polymeric alkoxide referred to as KPEG [16, p. 835], However,
sodium hydroxide has also been used in the past and most
likely will find increasing use in the future because of patent
applications that have been filed for modification to this
technology. This new approach will expand the technology's
applicability and efficacy and should reduce chemical costs by
facilitating the use of less costly sodium hydroxide [18]. A
variation of this reagent is the use of potassium hydroxide or
sodium hydroxide/tetraethylene glycol, referred to as ATEC,
that is more effective on halogenated aliphatic compounds
[21]. In some KPEG reagent formulations, dimethyl sulfoxide
(DMSO) is added to enhance reaction rate kinetics, presumably
by improving rates of extraction of the haloaromatic
contaminants [19][22].

The reagent (APEG) dehalogenates the pollutant to form
a glycol ether and/or a hydroxylated compound and an alkali
metal salt, which are water soluble byproducts. This treatment
process chemically converts toxic materials to non-toxic
materials. It is applicable to contaminants in soil [11, p. 1],
sludges, sediments, and oils [2, p. 183]. It is mainly used to
treat halogenated contaminants including polychlorinated
biphenyls (PCBs) [4, p. 137], polychlorinated dibenzo-p-dioxins
(PCDDs) [11, p. 1], polychlorinated dibenzofurans (PCDFs),
polychlorinated terphenyls (PCTPs), and some halogenated
pesticides [8, p. 3][14, p. 2]. This technology has been
selected as a component of the remedy for three Superfund
sites. Vendors should be contacted to determine the availability
of a treatment system for use at a particular site. The estimated
costs of treating soils range from $200-$500/ton. This bulletin
provides information on the technology applicability, the types
of residuals resulting from the use of the technology, the
latest performance data, site requirements, the status of the
technology, and where to go for further information.
Technology Applicability

The concentrations of PCBs that have been treated are
reported to be as high as 45,000 ppm. Concentrations were
* [reference number, page number]

-------
reduced to less than 2 parts per million per individual PCB
congener. Polychlorinated dibenzo-p-dioxins (PCDDs) and
polychlorinated dibenzofurans (PCDFs) have been treated to
nondetectable levels at part per trillion sensitivity. The process
has successfully destroyed PCDDs and PCDFs contained in
contaminated pentachlorophenol oil. For a contaminated
activated carbon matrix, direct treatment was less effective
and the reduction of PCDDs/PCDFs to concentrations less
than 1 ppb was better achieved by first extracting the carbon
matrix with a solvent and then treating the extract [15, p. 1].

All field applications of this technology to date have been
in various matrices and not on specific Resource Conservation
and Recovery Act (RCRA) listed wastes. The effectiveness of
APEG on general contaminant groups for various matrices is
shown in Table 1. Examples of constituents within contaminant
groups are provided in Reference 23, "Technology Screening
Guide for Treatment of CERCLA Soils and Sludges". This table
is based on the current available information or professional
judgment when no information was available. The proven
effectiveness of the technology for a particular site or waste
does not ensure that it will be effective at all sites or that the
treatment efficiency achieved will be acceptable at other sites.
For the ratings used for this table, demonstrated effectiveness
means that, at some scale, treatability was tested to show
that, for that particular contaminant and matrix, the technology
was effective. The ratings of potential effectiveness and no
Table 1
Effectiveness of APEG Treatment on
General Contaminant Groups for Various Matrices

Contaminant Groups

§
o

u
O
I

s
u
2
QC
Halogenated volatiles
Halogenated semivolatiles
Nonhalogenated volatiles
Nonhalogenated semivolatiles
PCBs
Pesticides (halogenated)
Dioxins/Furans
Organic cyanides
Organic corrosives
Volatile metals
Nonvolatile metals
Asbestos
Radioactive materials
Inorganic corrosives
Inorganic cyanides
Oxidizers
Reducers
Effectiveness
Sediments Oils Soil Sludge
V
T
Q
a
T
•
a
a
a
a
a
a
a
a
a
a
T
T
a
a
•
•
a
a
a
a
a
a
a
a
a
a
T
T
a
a
•
•
a
a
a
a
a
a
a
a
a
a
T
T
a
a
T
•
a
a
a
a
a
a
a
a
Q
• Demonstrated Effectiveness: Successful treatability test at
some scale completed
V Potential Effectiveness: Expert opinion that technology will work
Q No Expected Effectiveness: Expert opinion that technology will not
work
expected effectiveness are based upon expert judgment.
Where potential effectiveness is indicated, the technology is
believed capable of successfully treating the contaminant group
in a particular matrix. When the technology is not applicable
or will probably not work for a particular combination of
contaminant group and matrix, a no-expected-effectiveness
rating is given.

Limitations

The APEG technology is not intended as an in situ
treatment. APEG will dehalogenate aliphatic compounds if
the mixture is reacted longer and at significantly higher
temperatures than for aromatic compounds, it is
recommended that a related reagent KTEG be considered for
these contaminants. KTEG has been shown at laboratory
scale to be effective on halogenated aliphatic compounds
such as ethylene dibromide, carbon tetrachloride, ethylene
dichloride, chloroform, and dichloromethane (methylene
chloride) [18, p. 2]. The necessary treatment time and
temperature for KTEG use can be determined from laboratory
tests.

Treatability tests should be conducted prior to the final
selection of the APEG technology to identify optimum operating
factors such as quantity of reagent, temperature, and treatment
time. These tests can be used to identify such things as water
content, alkaline metals and high humus content in the soils,
glycol extractables content, presence of multiple phases, and
total organic halides that have the potential to affect processing
times and costs [19].

The treated soil may contain enough residual reagent
and treatment byproducts that their removal could be required
before final disposal. If necessary, such byproducts are usually
removed by washing the soil two or three times with water.
The soil will have to be neutralized by lowering the pH prior to
final disposal.

Specific safety aspects for the operation must be
considered. Treatment of certain chlorinated aliphatics in high
concentrations with APEG may produce compounds that are
potentially explosive (e.g., chloroacetylenes) and/or cause a
fire hazard. The use of DMSO or similar reagents may lead to
formation of highly flammable volatile organics (e.g., methyl
sulfide) [18, §IV C]. Severe corrosivity can be a concern when
DSMO is teamed with other APEG reagents. Alkaline reactive
materials such as metallic aluminum will compete with the
contaminants for the reagent and may produce hydrogen gas
(explosive). Vapors from heating oily soils, which are often
the matrix in which PCBs are found, can also create such
potential problems as fires and noxious fumes. These problems
can often be solved by taking appropriate corrective actions
during elevated temperature processing.

The operation must also be conducted with care because
of the elevated temperatures and production of steam, the
use of caustics in the process, and the presence of acids that
are used for neutralization. If DMSO is used, care must be
taken to prevent its coming into contact with skin, for it
enhances transport of PCBs through the skin, thus increasing
the risk of exposure.
Engineering Bulletin: Chemical Dehalogenation Treatment: APEG Treatment

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r
Technology Description

Figure 1 is a schematic of the APEG treatment process.

Waste preparation includes excavation and/or moving
the soil to the process where it is normally screened (1) to
remove debris and large objects and to produce particles that
are sufficiently small to allow treatment in the reactor without
binding the mixer blades.

Typically, the reagent components are mixed with the
contaminated soil in the reactor (2). The material must be
well mixed with the reagent to allow effective treatment.
Treatment proceeds inefficiently without mixing. This mixture
is heated to between 100° and 180° C. The reaction proceeds
for 1 to 5 hours depending upon the type, quantity, and
concentration of the contaminants. The treated material
goes from the reactor to a separator (3) where the reagent is
removed and can be recycled (4).

During the reaction, water is vaporized in the reactor,
condensed (5) and collected for further treatment or recycled
through the washing process, if required. Carbon filters (7)
are used to trap any volatile organics that are not condensed.
In the washer (6), the soil is neutralized by the additions of
acid. It is then dewatered (8) before disposal.
Process Residuals

There are three main waste streams generated by this
technology: the treated soil, the wash water, and possible air
emissions. The treated soil will need to be analyzed to
determine if it meets the regulatory requirements for the site
before final disposition can be made. The soil's pH must be
adjusted before disposal. The chemistry of this technology is
specific to halogenated organics and, based upon a test
conducted by the EPA in 1985, results in byproduct compounds
that appear to be neither toxic nor of concern. In that test the
EPA checked for 1) mutagenicity, 2) toxicity, and 3)
bioaccumulation/bioconcen-tration of the byproducts of two
different contaminants: tetrachlorobenzene and 2,3,7,8 -
TCDD that had been treated by the process [3, p. 80]. The
individual byproduct chemical compounds were not
determined. These compounds and the residual levels of
reagent or catalyst did not present a serious health or
environmental problem [12, p. 2].

Waste wash water contains only trace amounts of
contaminants and reagents and would be expected to meet
appropriate discharge standards, enabling it to be discharged
to a local, publicly owned treatment works or receiving stream.
Volatile air emissions can be released due to the heating and
mixing that occurs with the process. They are usually captured
by condensation and/or on activated carbon. The
contaminated carbon is usually incinerated.
Site Requirements

APEG treatment units are transported by trailers [13, p.
54]. Therefore, adequate access roads are required to get the
unit to the site. The system that operated in Guam, which
used a 1.5- ton batch reactor, required an area of 100 feet by
100 feet.

Energy requirements involve heating the reactor and
removing the water by volatilization. For the reactor used in
Guam, a standard 440V, three-phase electrical service was
required along with a diesel steam-generating plant rated at
Figure 1
APEG Treatment Process
Emissions
Treated
Emissions
Water Acid

Waste
Preparation
0)

Screened
Soil

Reactor
(2)
j

_^b.

Separator
(3)

Soil

t t
Washer
(6)

Soil

Dewater
(8)

Reagent Recycle (4)
.Oversized
Rejects
Engineering Bulletin: Chemical Dehalogenation Treatment: APEG Treatment

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600 Ib/h and 80 psi [13, p. 53]. A standard municipal water
supply, or equivalent, is adequate for this process.

Contaminated soils or other waste materials are hazardous
and their handling requires that a site safety plan be developed
to provide for personnel protection and special handling
measures.

A means of containing and cleaning up accidental spills
must be provided. The reagents (KOH, acids, etc.) should be
stored in drums with containment beneath and provisions to
pump any spills to a holding area for neutralization [19, p. 2].

The process residuals normally must be stored until their
level of contaminants are verified to be below those established
for the site. Depending upon the site, a method to store
waste may be necessary. Storage capacity will depend on
waste volume.

Onsite analytical capabilities are highly desirable.
Extraction equipment and gas chromatography/mass
spectometer capabilities should be available to measure
contaminants of interest and to provide information for process
control.
Performance Data

This technology's performance has been evaluated from
bench-scale tests to field tests in large reactors. Table 2
summarizes the results of several more important applications
of the technology and their results.

RCRA Land Disposal Restrictions (LDRs) that require
treatment of wastes to best demonstrated available technology
(BOAT) levels prior to land disposal may sometimes be
determined to be applicable or relevant and appropriate
requirements (ARARs) for CERCLA response actions. The
APEG treatment technology can produce a treated waste that
meets treatment levels set by BOAT, but may not reach these
treatment levels in all cases. The ability to meet required
treatment levels is dependent upon the specific waste
constituents and the waste matrix. In cases where APEG
treatment does not meet these levels it still may, in certain
situations, be selected for use at the site if a treatability
variance establishing alternative treatment levels is obtained.
EPA has made the treatability variance process available in
order to ensure that LDRs do not unnecessarily restrict the use
of alternative and innovative treatment technologies.
Treatability variances may be justified for handling complex
soil and debris matrices. The following guides describe when
Table 2
APEG Field Performance Data
Site/Date
Signo Trading
NY/1982
Montana Pole
Butte, MT/1986
(16, p. 838)
Western
Processing
Kent, WA/1 986
[16, p. 838]
Wide Beach
Erie County, NY/
1985
Guam
U.SA/1988
793 gal. reactor
[13, p. 43]
Bengart & Memel
Buffalo, NY/1986
55 gal. drum
[10, p. 13]
Economy
Products
Omaha, NE/1 987
Contaminant/
Waste Form
dioxin/liquid
dioxin
furans/oil
dioxin/liquid
and sludge
PCBs (Aroclor
1 254)/soil
PCBs/soil
PCBs/soil
TCDD, 2, 4-D,
2, 4, 5-T/liquid
Concentration
Before
1 35ppb
147-83,923 ppb
120 ppb
1 20 ppm
2500* ppm with
hot spots as high
as 45,860 ppm
51 out of 52
drums, 1 08 ppm
1.3 ppm
1 7,800 ppm
2,800 ppm
Concentration
After
<1 ppb
<1 ppb
<0.3 ppb
<2 ppm
<1ab ppm
<27 ppm
ND
334 ppm
55 ppm
Volume
Treated
15 gallons
1 0,000 gallons
7,550 gallons
1 ton
22 tons soil
3.4 tons
crushed rock
52 fifty-five
gallon drums
20 gallons
a = value is an average value

b = per resolvable PCB cogener
Engineering Bulletin: Chemical Dehalogenation Treatment: APEG Treatment

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and how to seek a treatability variance for soil and debris:
Superfund LDR  Guide #6A, "Obtaining a Soil and Debris
Treatability Variance for Remedial Actions," (OSWER Directive
9347.3-06FS)  [20]; and Superfund  LDR  Guide #6B,
"Obtaining a Soil and Debris Treatability Variance for Removal
Actions"  (OSWER Directive 9347.3-07FS) [17].  Another
approach could be to use other treatment techniques in series
with APEG treatment to obtain desired treatment levels.
Technology Status

    The APEG process has been selected for cleanup of PCB-
contaminated soils at three Superfund sites:  Wide Beach,
New  York (September  1985), Re-Solve,  Massachusetts
(September 1987), and Sol Lynn, Texas (March 1988). Wide
Beach is expected to start operation in the summer of 1990
[9, p. 99] [19].

    This  technology has received approval  from the EPA's
Office of Toxic Substance under the Toxic Substances Control
Act for PCB treatment.

    Significant advances are currently being  made to the
APEG technology. These advances employ water rather than
costly PEG to wet the soil  and require shorter reaction times
and less energy.  These advances should greatly enhance the
economics of the process.  Performance information on this
modified process is not available at this time for  inclusion in
this bulletin [18].

    This technology uses standard equipment. The reaction
vessel must be equipped to mix and heat the soil and reagents.
A detailed engineering design for a continuous feed, full-scale
system for use in Guam  is currently being completed.. It is
estimated that a full-scale system can be fabricated and placed
in operation in 6 to 12 months. Costs to use APEG treatment
are expected to be in a range of $200-$500/ton.
 EPA Contact

     Technology-specific questions regarding APEG technology
 may be directed to:

     Charles j. Rogers
     U.S. EPA Risk Reduction Engineering Laboratory
     26 West Martin Luther King Drive
     Cincinnati, Ohio 45268
     Telephone:  FTS 684-7757 or (513) 569-7757
                REFERENCES
1.   Adams, G.P., and R.L Peterson.  Non-Sodium Process
    for Removal of PCBs From Contaminated Transformer
    Oil, Presented at the APCA National Meeting in
    Minneapolis, 1986.
2.   Brunelle, D.J., and D. Singleton. Destruction/Removal
    of Polychlorinated Biphenyls From Non-Polar Media —
    Reaction of PCB with Poly (Ethylene Glycol)/KOH.
    Chemosphere, 12:  183-196,1983.
3.   Carpenter, B.H. PCB Sediment Decontamination
    Processes—Selection for Test and Evaluation, Research
    Triangle Institute, 1987.
4.   Carpenter, B.H., and D.L Wilson.  Technical/Economic
    Assessment of Selected PCB Decontamination
    Processes.  Journal of Hazardous Materials, 17:  125-
    148, 1988.
5.   des Rosiers, Paul E. APEG Treatment of Dioxin- And
    Furan-Contaminated Oil at an Inactive Wood Treating
    Site in Butte, Montana, Presented at the Annual
    Meeting of the American Wood Preserves Institute,
    Washington, D.C., 1986.
6.   Kernel, A., Charles j. Rogers, and H. Sparks. KPEG
    Application From the Laboratory to Guam.  In:
    Proceedings of the Third International Conference on
    New Frontiers for Hazardous Waste Management. EPA/
    600/9-89/072, Pittsburgh, Pennsylvania, 1989.
 7.    Lauch, R., and others. Evaluation of Treatment
    Technologies for Contaminated Soil and Debris. In:
     Proceedings of the Third International Conference on
     New Frontiers for Hazardous Waste Management. EPA/
     600/9-89/072, Pittsburgh, Pennsylvania, 1989.
 8.   Locke, B. and others. Evaluation of Alternative
     Treatment Technologies for CERCLA Soils and Debris
     (Summary of Phase I and Phase II). EPA Contract No.
     68-03-3389, U.S. Environmental Protection Agency,
     Risk Reduction Engineering Laboratory, Cincinnati,
     Ohio,  (no date).
 9.   NATO/CCMS.  Demonstration of Remedial Action
     Technologies for Contaminated Land and
     Groundwater. In: Proceedings of the NATO/CCMS
     Second International Workshop, Hamburg, Federal
     Republic of Germany, 1988. pp. 97-99.
 10.  Novosad, C.F., E. Milicic, and R. Peterson.
     Decontamination of a Small PCB Soil Site by the Galson
     APEG Process, Presented before the Division of
     Environmental Chemistry, American Chemical Society,
     New Orleans, 1987.
 11.  Peterson, R.L, M. Edwins, and C. Rogers.  Chemical
     Destruction/Detoxification of Chlorinated Dioxins in
     Soils.  In:  Proceedings of the Eleventh Annual Research
     Symposium, Incineration and Treatment of Hazardous
     Wastes. EPA/600/9-85/028,1985.
 12.  Peterson, R.L., and others. Comparison of Laboratory
     and Field Test Data in the Chemical Decontamination
     of Dioxin Contaminated Soils, Presented at the ACS
     Meeting in New York, New York, 1986.
  Engineering Bulletin: Chemical Dehalogenation Treatment: APEG Treatment

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