NCD980602163_19920301_Warren County PCB Landfill_SERB C_A Citizen's Guide to Glycolate Dehalogenation-OCR

&EPA
United States
Environmental Protection
Agency
Office of
Solid Waste and
Emergency Response
EP A/542/F-92/005
March 1992
A Citizen's Guide To
Glycolate Dehalogenation
Technology Innovation Office Technology Fact Sheet
What Is Glycolate
Dehalogenatlon?
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.
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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 I .
The process is illustrated in greater
detail on page 3 and the following
discussion.
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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 haz.ardous 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 Worlcs, 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 AnJnnovit1ve freatffierrt /•··· · ··
Technology?·
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data. under II variety e>f <>P4tfatlng con~IW:>l'ls 11re >
called /nnovat/vetr.iatmenft~chn~logles; .
Figure 1
i g,
iii
J:
Conceptual Diagram of Dehalogenatlon
Ha2ardous Halogen Compound ----,►~ Treated --►-Nonhazardous Dehalogenated Compound
Halogen
Halogen
Halogen
and
Halogen
APEG
Reagent
Peg
2
Halogen
and
Peg
A-Halogen
(a salt)
Figure 2
Glycolate Dehalogenatlon Proceu Flow
• Over1lzed Reject•
(Boulder,, Log,, Etc.)
to Other Treatment/Dl1po1■I
Conden1or
l
Eml1llon1
Recycled
Reagent
Why Consider Glycolate Dehalogenation?
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.
3
EmlNlon1 Control
(Activated Cwbon)
Water
Treated
Eml11lon1
Water
to Publicly
Owned
Treatment
Work• t
• ~
Treated
Solle
~ Further
Teellng ■nd
Treatment If
Nec1111ry
What Contaminants Can It Treat?
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.
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WIii Dehalogenatlon 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.
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Table 1
SHe Locations Where Glycolate
Dehalogenatlon Has Been Selected*
Site Name
Re-Solve
Palmetto
Wood
Preserving
Sol Lynn/
Industrial
Transformers
Location Type of Faclllty
Massachusetts Chemical
South
Carolina
Texas
·reclamation
Wood preserving
Transformer and
solvent recycler
•All waste types and site conditions are not similar.
Each site must b9 individually investigated and tested.
Engineering and scientific judgment must be used to
determine if a technology is appropriate for a site.
: ~~A ,1~,~;~ thl; f~ct sheet t~ p;ov~• bas1J<1~f~~.tldh 6H ;,~cci~tj di1t•iogeri;tr«ihY~aJit~n!ltechnlc#tl :
? reports are listed below/ The documents containing a "PB" designation are available by'contactlng Jhe . . .
Natlori~fTechnlcal Information Service (NT1S)at1-800-336:-4100. Mall or~ers can be untto: .. ·· .
. Natl~nai Technlcannfo;matlon· S..~l<:e · Sprlngfleld, VA 22161
t ~Wr ct~iti,,,;nts rtiay be obtained by contacting:)) ... ·•·.·
{ ) _· .... Center for Envlronn,ental.Research>l~to~f1o~·-•···· .
>>••••••-•••••••· <• <•tr\••••••••~W,•t•-,...r1111•P.1tti•r•1<1tjg· 0r1ve · ····. ><Cincinnati, OH 45268 ··
[phone] . ·.
·······f ~erJ···~Y--~~···~•·~harg:••for the~•·de>eurnents.·•
~~~l~lc Dehydre>halogeriatlon:IA Chemical Destr~ctlon.Method for Halogenated Organl~s. Proje~}
! j ;> !it~i::::~:-::: J;Ef'·.P,oco .. 1o,JrNtk1g Ch~rh\ated W•S!"~ ~;~1~~,
> ~ jg,,o;lt1v: Tec~hology: ~lycolate Dehalogenat~~. ·. EPAl9200.5-254FS; P~~274;26 .. · ..
•••···•·•··•···••·•···••:li··•···••1•·••···. ···•·.I;J~h,••n.••·•nd· others; _-;·Eva1uat1on•·of _Treatment•••T~hric,1og1~ --,o,···eont~i~ited·••~1i•••~~d•·o.br1'··;•··•····••·•·•··•·••••·•···•··•••• •·• ptOCHdlngs of the Third lnterriatlonal Conference on New Frontiers for HazardousWijste Manage:. < > }< < ment/eltt$burgh, PA, 1989, EPA/600/9~/072; . .. .. . . ··
/ 1'~hi,c,logy Scre:nlng, Gulde for Treatment of CE~tu<So;,; .~ct . Sludges, EPA.1540/2-88IC>04.
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.
4 •u.s. Government Printing Office: 1992 -648-080/60005