U"
United States
Environmental Protection
Agency
Off ice of
Solid Waste and
Emergency Response
EPA/542/F-92/005
March 1992
&EPA
A Citizen's Guide To
Glycolate Dehalogenation
Technology Innovation Office
.Technology Fact Sheet
CONTENTS
Page
What to Glycolate
Dehalogenation? 1
How Does It Work?
Why Consider
Glycolate
DehsJogenatfon? 3
What Contaminants
Can It Treat? 3
Will Dehatogenatlon
Work At Every Site? 4
Where Is
Dehalogenation
Being Selected? 4
For More information 4
What Is Glycolate
Dehalogenation?
Glycolate dehalogenation is the process
of using a chemical reagent (a glycol in
this case) to remove halogen from
contaminants, consequently rendering
them less hazardous. A chemical
reagent is a substance used to react with
and change another substance. This
dehalogenation process can be used on
halogenated contaminants such as PCBs
and dioxins that may be found in soil
and oils.
One chemical reagent that removes
halogen is called an APEG reagent. It
consists of two parts: an alkali metal
(hence the A in APEG) and
Polyethylene Glycol (PEG), which is a
substance similar to antifreeze. Alkali
metals, such as sodium and potassium,
have basic (high pH) properties, as do
ammonia and milk of magnesia.
A conceptual diagram of
dehalogenation is shown in Figure 1.
The process is illustrated in greater
detail on page 3 and the following
discussion.
What Are Halogens?
Halogens are non-metallic elements such as Chlorine, Bromine, Iodine,
and Fluorine. Halogens sre Incorporated into larger chemical
structures to form halogenated compounds. Companies manufacture
haloganated compounds because they provide a variety of uses for
humans. For example, one type of halogenated compound,
polychforlnated btphenyls (PCBs), was once used in high voltage
electrical transformers because It conducted heat well while being a
good electrical Insulator, in addition, halogenated compounds are
used to produce pesticides because their addition causes the toxtelty
needed to control pests. Halogenated compounds are also commonly
used in water treatment, swimming pools, plastic piping and textiles,
among other materials.
Glycoiate Dehalogenation Profile
Mainly used to treat halogenated aromatic organic contaminants, particularly PCBs and dfoxins.
Chemically converts toxic materials to toss toxic materials.
Involves heating and physically mixing contaminated soils with chemical reagents.
is a transportable technology that can be brought to the site.
U.S. Environmental Protection Agency
Producedbythe
(PH2J)
77 West Jackson Boulevard, 12th
Chicago, IL 60604-3590
Printed on Recycled Paper
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How Does It Work?
A contaminant being treated with glycolate dehalogenation
undergoes five major phases, which are shown in Figure 2
on page 3. These five phases are preparation, reaction,
separation, washing, and dewatering. During the first
phase, the contaminated waste is dug up and moved to a
staging area — a place where the contaminated material is
prepared For treatment. The waste is then sifted to remove
debris and large objects, such as boulders and logs.
Contaminated soils and the APEG (Alkaline PolyEthylene
Glycol) reagent are then put into a treatment vessel where
they are heated and mixed to form a sludge. The heating
helps the PEG part of the APEG reagent replace some of the
halogens in the halogenated compound. The halogen and
the A part of the APEG reagent chemically combine to form
a salt. This reaction is shown in Figure 1.
During the heating process, some volatile air emissions,
which may be contaminated, are given off. These vapors
are collected in a condenser, where they are separated into
water and air emissions. The water can be used during a
later step in the process, while the air emissions are captured
by activated carbon filters. These filters are then
transported off-site for either regeneration, incineration, or
disposal into an environmentally safe landfill regulated by
the Resource Conservation Recovery Act (RCRA) or the
Toxic Substance Control Act (TSCA). A slurry—less toxic
wet mixture of soil and APEG reagent—is the result of the
reactor phase.
The resulting slurry then goes to the separator, where the
APEG reagent is physically separated and recycled for
future use in the treatment vessel. The soil contains the by-
products of the dehalogenation reaction and some residual
APEG reagent. These by-products (shown in Figure 1)
are a halogen salt, which consists of an Alkali metal (A)
and a halogen, and a partially halogenated compound.
This partially halogenated compound does not accumulate
in living tissue and is therefore less hazardous than the
original compound which does accumulate in living tissue.
The soil then goes to a washer, where the water from the
condenser is added. The residual APEG reagent is extracted
from the soil and recycled. The glycolate dehalogenation
treatment can make the soil basic because of the addition of
the APEG reagent which has basic properties. Therefore
during the washing phase, acid is added in order to
neutralize the soil. Neutralization reactions involve mixing
acids and bases in appropriate amounts in order to get a
compound that is neither highly basic (high pH) or highly
acidic (low pH).
The soil then goes to a dewatering phase where the water
and soil are separated. The water is treated until it meets the
appropriate pollution levels set forth by the local National
Pollutant Discharge Elimination System. When the water is
free of contaminants, it can be discharged to a Publicly
Owned Treatment Works, a receiving stream, or other
appropriate discharge areas. The soil is tested for
contaminants. Following testing, the soil is either retreated,
redeposited, or put into an environmentally safe RCRA or
TSCA landfill.
What is An Innovative Treatment
Technology?
Treatment technologies are processes applied
to the treatment of hazardous waste or
contaminated materials to permanently alter
their condition through chemical, biological, or
physical means. Technologies that have been
tested, selected or used for treatment of
hazardous waste or contaminated materials but
lack well-documented cost and performance 0
data under a variety of operating conditions are
called Innovative treatment technologies.
Figure 1
Conceptual Diagram of Dehalogenation
Hazardous Halogen Compound
Halogen Halogen
Treated
and
APEG
Reagent
Halogen
Halogen
Treatment
Vessel
Nonhazardous Dehalogenated Compound
Peg Halogen
and
A-Halogen
(a salt)
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Figure 2
Glycolate Dehalogenatlon Process Flow
Emissions
Emissions Control
(Activated Carbon)
Treated
Emissions
Water
Water
to Publicly
Recycled
Reagent
-*-J
Treatment
Works
Treated
Soils
J
Oversized Rejects
(Boulders, Logs, Etc.)
to Other Treatment/Disposal
Further
Testing and
Treatment If
Necessary
Why Consider Glycolate Dehalogenation? What Contaminants Can It Treat?
Dehalogenation has proven to be effective in removing
halogens from hazardous halogenated organic compounds,
such as dioxins, furans, PCBs and certain chlorinated
pesticides, and therefore rendering them non-toxic. An
advantage of this technology is that it is usually less
expensive than incineration. It requires standard treatment
vessel equipment to mix and heat the soils and reagents, and
the energy requirements are moderate. In addition, the
treatment time required is short, and operation and
maintenance costs are relatively low. The technology can
be brought to the site, allowing hazardous wastes to be
excavated and treated onsite.
Glycolate dehalogenation reactors have been successfully
applied to sites containing PCB-contaminated waste oil.
One such full-scale treatment vessel has a single batch
capacity of 80 cubic yards and can treat 160 to 200 cubic
yards of waste per day. Presently, significant advances are
being made to further improve this technology. These
advances will shorten the reaction times, reduce the energy
required, and make the process more cost effective.
This technology is most successful in treating contaminants
that have acquired cancer-causing or toxic properties as a
result of having chlorine in their chemical structure. Such
contaminants include dioxins, furans, PCBs, and some
pesticides.
What Is Chemical Treatment?
Chemical treatment Is the process of changing
the structure of a hazardous material either by
adding, deleting, or rearranging smaller chemi-
cal components of the material. The purpose of
chemical treatment Is to reduce the hazardous
characteristics of chemically contaminated
material. This structural change (I.e., add,
delete, rearrange) Is accomplished through the
action of chemical reagents. One specific type
of chemical reagent wilt not act on all types of
hazardous waste. It Is the chemical composi-
tion of the hazardous material that determines
the reagent to be used. This matching of
reagent with the type of contaminant must be
precise If chemical treatment Is to be effective.
U.S. Environmental Protection Agency
Region 5. library (PL-12
// WCCT Jackson Boulevard, 12th Hoor
Chicago, IL 60604-3590
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Will Dehalogenation Work At Every Site?
Glycolate dehalogenation is limited as a treatment method
to halogenated compounds. It is not effective in situations
where the contamination is highly concentrated, such as
pure waste oils. Other characteristics of the contaminated
material that interfere with its effectiveness are high water
content, acidity, high natural organic content of the soil,
and/or the presence of other alkaline materials similar to the
reagents, such as aluminum and other metals. The proven
effectiveness of the technology for a particular site or waste,
as shown in Table 1, does not guarantee that it will be
effective at all sites. Finally, the end products of the
dehalogenation process may require further treatment to
eliminate the by-products still left in the soil and water.
Where Is Dehalogenation Being Selected?
Table 1 at right lists some examples of Superfund sites
where glycolate dehalogenation has been selected as a
treatment method. There are other types of dehalogenation
processes being considered and tested as well. Additionally,
there are treatment technologies that enhance the
effectiveness of dehalogenation.
Table 1
Site Locations Where Glycolate
Dehalogenation Has Been Selected*
Site Name
Re-Solve
Palmetto
Wood
Preserving
Sol Lynn/
Industrial
Transformers
Location Type of Facility
Massachusetts
South
Carolina
Texas
Chemical
reclamation
Wood preserving
Transformer and
solvent recycler
'All waste types and site conditions are not similar.
Each site must be individually investigated and tested.
Engineering and scientific judgment must be used to
determine if a technology is appropriate for a site.
For More Information
EPA prepared this fact sheet to provide basic information on glycolate dehalogenation. Additional technical
reports are listed below. The documents containing a "PB" designation are available by contacting the
National Technical Information Service (NTIS) at 1-800-336-4700. Mail orders can be sent to:
National Technical Information Service
Springfield, VA 22161
Other documents may be obtained by contacting:
Center for Environmental Research Information
26 West Martin Luther King Drive
Cincinnati, OH 45268
(513)569-7562
There may be a charge for these documents.
Catalytic Dehydrohalogenation: A Chemical Destruction Method for Halogenated Organlcs, Project
Summary, EPA/600/52-86/113.
Comprehensive Report on the KPEG Process for Treating Chlorinated Wastes, PB90-163643.
• innovative Technology: Glycolate Dehalogenation, EPA/9200.5-254FS; PB90-274226.
Lauch, R. and others. "Evaluation of Treatment Technologies for Contaminated Soil and Debris";
Proceedings of the Third international Conference on New Frontiers for Hazardous Waste Manage-
ment. Pittsburgh, PA, 1989, EPA/600/9-89/072.
• Technology Screening, Guide for Treatment of CERCLA Soils and Sludges, EPA/540/2-88/004.
NOTICE: This fact sheet is intended solely as general guidance and information. It is not intended, nor can it be relied upon, to create any rights enforceable by any
party in litigation with the United States. The Agency also reserves the right to change this guidance at any time without public notice.
•U.S. Government Printing Office: 1992 — 648-080/60005
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