United States
                      Environmental Protection
                                                Off ice of
                                                Solid Waste and
                                                Emergency Response
               March 1992
                     A  Citizen's  Guide  To
                     Glycolate  Dehalogenation
Technology Innovation Office
                                                                 .Technology Fact Sheet
 What to Glycolate
 Dehalogenation?     1
  How Does It Work?
 Why Consider
 DehsJogenatfon?      3
 What Contaminants
 Can It Treat?         3
 Will Dehatogenatlon
 Work At Every Site?   4
 Where Is
 Being Selected?      4
 For More information  4
                            What Is Glycolate

                            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
                               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	
           77 West Jackson Boulevard, 12th
           Chicago, IL  60604-3590
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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

                                        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
Nonhazardous Dehalogenated Compound

    Peg          Halogen
                                (a salt)

                                                  Figure 2
                                  Glycolate Dehalogenatlon Process Flow
                                                                 Emissions Control
                                                                 (Activated Carbon)
                                                                                                  to Publicly
      Oversized Rejects
    (Boulders, Logs, Etc.)
 to Other Treatment/Disposal
                                                                                     Testing and
                                                                                     Treatment If
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
           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

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


Sol Lynn/
Location        Type of Facility


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

    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