United States
                            Environmental Protection
                            Agency
Office of Emergency and
Remedial Response
Washington, DC 20460
Office of
Research and Development
Cincinnati, OH 45268
                            Superfund
EPA/540/2-91/008
May 1991
                            Engineering Bulletin
                            Thermal  Desorption  Treatment
Purpose

    Section 121 (b) of the Comprehensive Environmental Re-
sponse, 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 maxi-
mum extent practicable" and to prefer remedial actions in
which treatment "permanently and significantly reduces the
volume, toxicity, or mobility of hazardous substances, pollut-
ants  and  contaminants as a principal element." The Engi-
neering 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,  contrac-
tors,  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 hazard-
ous 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

    Thermal  desorption is an ex situ means to  physically
separate volatile and some semivolatile contaminants from
soil, sediments, sludges, and filter cakes. For wastes contain-
ing up to 10% organics or less, thermal desorption can be
used alone for site remediation.  It also may find applications
in conjunction with other technologies or be appropriate to
specific operable units at a site.

    Site-specific treatability studies  may be  necessary to
document  the  applicability and performance  of a thermal
desorption system. The EPA contact indicated at the end of
this bulletin can assist in the definition of other contacts and
sources of information necessary for such treatability studies.

    Thermal  desorption is applicable to organic wastes and
generally is not used for treating metals and other inorganics.
Depending on the specific thermal desorption vendor se-
lected, the technology heats contaminated media between
200-1000°F,  driving  off water  and volatile contaminants.
  Offgases may be burned in  an afterburner, condensed to
  reduce the volume to be disposed, or captured by carbon
  adsorption beds.

      Commercial-scale units exist and are in operation. Ther-
  mal desorption has been selected at approximately fourteen
  Superfund sites [1]* [2]. Three Superfund Innovative Technol-
  ogy Evaluation demonstrations are planned for the next year.

      The final determination of the lowest cost alternative will
  be more  site-specific than process equipment dominated.
  This bulletin provides information on the technology applica-
  bility,  limitations, the types of residuals produced, the latest
  performance data, site requirements, the status of the tech-
  nology, and sources for further information.
  Technology Applicability

      Thermal desorption has been proven effective in treating
  contaminated soils, sludges, and various filter cakes. Chemi-
  cal contaminants for which bench-scale through full-scale
  treatment data exist include primarily volatile organic com-
  pounds (VOCs), semivolatiles, and even higher boiling point
  compounds, such as  polychlorinated biphenyls  (PCBs)
  [3][4][5][6].  The technology is not  effective in separating
  inorganics from the contaminated medium.  Volatile metals,
  however, may  be removed by higher temperature thermal
  desorption systems.

      Some metals may be volatilized by the thermal desorp-
  tion process as the contaminated medium is heated.  The
  presence of chlorine in the waste can also significantly affect
  the volatilization of some metals, such as lead.  Normally the
  temperature of the medium achieved by the process does not
  oxidize the metals present in the contaminated medium [7, p.
  85].

      The process is applicable for the separation of organics
  from refinery wastes, coal tar wastes, wood-treating wastes,
  creosote-contaminated soils, hydrocarbon-contaminated soils,
  mixed (radioactive and hazardous) wastes, synthetic rubber
  processing wastes, and paint wastes [8, p. 2][4][9].

      Performance data presented in this bulletin should not be
  considered directly applicable to other Superfund sites.  A
  number of variables, such as the specific mix and distribution
* [reference number, page number]
                                                                                         Printed on Recycled Paper

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                       Table I
           RCRA Codes for Wastes Treated
                by Thermal Desorption
   Wood Treating Wastes                      K001
   Dissolved Air Flotation (DAF) Float             K048
   Slop Oil Emulsion Solids                     K049
   Heat Exchanger Bundles Cleaning Sludge       K050
   American Petroleum Institute (API)
     Separator Sludge                         K051
   Tank Bottoms (leaded)                      K052
                       Table 2
        Effectiveness of Thermal Desorption on
        General Contaminant  Groups for Soil,
         Sludge, Sediments, and Filter Cakes


Contaminant Croups



.S
1
0





.a
§
21
g


1

Halogenated volatiles
Halogenated semivolatiles
Nonhalogenated volatiles
Nonhalogenated semivolatiles
PCBs
Pesticides
Dioxins/Furans
Organic cyanides
Organic corrosives
Volatile metals
Nonvolatile metals
Asbestos
Radioactive materials

Inorganic corrosives
Inorganic cyanides
Oxidizers
Reducers
Effectiveness
Sedi- Filter
Soil Sludge ments Cakes







T
a
•
a
a
a

a
a
a
a
V
V
T
T
T
V
V
T
a
T
a
a
a

a
a
a
a
T
V
T
V
T
T
T
T
a
T
a
a
a

a
a
a
a
•
•
•
•
T
T
T
T
a
T
a
a
a

a
a
a
a
• Demonstrated Effectiveness: Successful treatability test at some scale
completed
T Potential Effectiveness: Expert opinion that technology will work
Q No Expected Effectiveness: Expert opinion that technology will not
work
of contaminants, affect system  performance.   A thorough
characterization of the site and a well-designed and con-
ducted treatability study are highly recommended.

    Table 1 lists the codes for the specific Resource Conserva-
tion and Recovery Act (RCRA) wastes that have been treated
by this technology  [8, p. 2][4][9]. The indicated codes were
derived from vendor data where the objective was to deter-
mine thermal desorption  effectiveness for these specific in-
dustrial wastes. The  effectiveness of thermal desorption on
general contaminant groups for various matrices is shown in
Table 2. Examples of constituents within contaminant groups
are provided in "Technology Screening Guide For Treatment
of CERCLA Soils and Sludges" [7, p. 10]. This table is based on
the current available information  or  professional judgment
where 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
efficiencies 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 the tech-
nology was effective for that particular contaminant and me-
dium.  The ratings of potential effectiveness or no expected
effectiveness are both based upon expert judgment.  Where
potential effectiveness is indicated, the technology is believed
capable of successfully  treating the contaminant group in a
particular medium. When the technology is not applicable or
will probably not work for a particular combination of con-
taminant group and medium, a no  expected  effectiveness
rating is given. Another source of general observations and
average removal efficiencies for different treatability groups is
contained in the Superfund Land Disposal Restrictions (LDR)
Guide #6A, "Obtaining  a Soil and Debris Treatability Variance
for Remedial Actions,"  (OSWER Directive 9347.3-06FS, Sep-
tember 1990)  [10] and Superfund LDR Guide #6B, "Obtain-
ing a Soil and Debris Treatability Variance for  Removal Ac-
tions," (OSWER  Directive 9347.3-06BFS,  September  1990)
[11].


Limitations

    The primary technical factor affecting thermal desorption
performance is the maximum bed temperature achieved. Since
the basis of the process is physical removal from the medium
by volatilization, bed temperature directly determines which
organics will be removed.

    The contaminated  medium must contain at least 20 per-
cent solids to  facilitate  placement of the waste  material into
the desorption equipment [3, p. 9].  Some systems specify a
minimum of 30 percent solids [12, p. 6].

    As the medium is heated and passes through the kiln or
desorber, energy is lost in heating moisture contained in the
contaminated  soil. A very high moisture content can result in
low contaminant volatilization or a need to recycle the soil
through  the  desorber.  High moisture  content,  therefore,
causes increased treatment costs.

    Material handling of soils that are tightly aggregated or
largely clay, or that contain rock fragments or particles greater
than 1 -1.5 inches can result in poor processing performance
due to caking. Also, if a high fraction of fine silt or clay exists
in the matrix, fugitive dusts  will be generated [7, p. 83] and a
greater dust loading will be placed on the downstream air
pollution control equipment [12, p. 6].

    The  treated medium will typically contain less than 1
percent moisture.  Dust can easily form in the transfer of the
treated medium from the desorption unit, but can be mitigated
by water sprays.  Normally,  clean water from air pollution
control devices can be used for this purpose.

    Although  volatile organics are the primary target of the
thermal desorption technology, the total organic loading is
limited by some systems to up to  10 percent or  less [13, p. II-
                                                       Engineering Bulletin: Thermal Desorption Treatment

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30]. As in most systems that use a reactor or other equipment
to process wastes, a medium exhibiting a very high pH (greater
than 11) or very low pH (less than 5) may corrode the system
components [7, p. 85].

    There is evidence with some system configurations that
polymers may foul and/or plug heat transfer surfaces [3, p. 9].
Laboratory/field  tests  of thermal  desorption systems have
documented the deposition of insoluble brown tars (presum-
ably phenolic tars) on internal system components  [14, p.
76].

    High concentrations of inorganic  constituents  and/or
metals will likely not be effectively treated by thermal desorp-
tion.  The maximum bed temperature and the presence of
chlorine can result in volatilization of some inorganic constitu-
ents in the waste, however.

Technology Description

    Thermal desorption is any of a number of processes that
use either indirect or direct heat exchange to vaporize organic
contaminants from soil or sludge. Air, combustion  gas,  or
inert gas is used as the transfer medium  for the vaporized
components.  Thermal desorption systems are physical sepa-
ration processes and are not designed to provide high levels
of organic destruction, although the higher temperatures of
some systems will result in localized oxidation and/or pyroly-
sis.  Thermal desorption is not incineration, since the destruc-
tion of organic contaminants is not the desired result.  The
bed temperatures  achieved and residence times designed
into thermal desorption systems will volatilize selected con-
taminants, but typically not oxidize or destroy them.   System
performance is typically measured by comparison of untreated
soil/sludge  contaminant levels with those of the  processed
soil/sludge. Soil/sludge is typically heated to 200 - 1000° F,
based on the thermal desorption system selected.

    Figure 1 is a general schematic of the thermal desorption
process.
    Waste material handling (1) requires excavation of the
contaminated soil or sludge or delivery of filter cake to the
system. Typically,  large objects greater than 1.5  inches are
screened from the medium and rejected. The medium is then
delivered by gravity to  the desorber inlet or conveyed  by
augers to a feed hopper [8, p. 1 ].

    Significant system variation exists in the desorption step
(2). The dryer can  be an indirectly fired rotary asphalt kiln, a
single (or set of) internally heated screw auger(s), or a series of
externally heated distillation chambers.  The latter process
uses annular augers to move the medium from one volatiliza-
tion zone to the next. Additionally, testing and demonstration
data exist for a fluidized-bed desorption system [12].

    The waste is intimately contacted with a heat transfer
surface, and highly volatile components (including water) are
driven off. An inert gas, such as nitrogen, may be injected in a
countercurrent sweep stream to prevent contaminant com-
bustion and to vaporize and remove the contaminants [8, p.
1][4].  Other systems simply direct the hot gas stream from
the desorption unit [3, p. 5][5].

    The actual bed temperature and residence time are the
primary factors affecting performance in thermal desorption.
These parameters are controlled in the desorption unit  by
using  a series of increasing temperature zones [8, p. 1 ], mul-
tiple passes of the medium through the desorber where the
operating temperature  is  sequentially  increased, separate
compartments where the heat transfer fluid  temperature is
higher, or sequential processing into higher temperature zones
[15][16]. Heat transfer fluids used to date include hot com-
bustion gases, hot oil, steam, and molten salts.

    Offgas from desorption is typically processed (3) to  re-
move particulates. Volatiles in the offgas may be burned in an
afterburner, collected on activated carbon, or recovered in
condensation equipment. The selection of the gas treatment
system will depend on the concentrations of the contaminants,
cleanup standards, and  the economics of the offgas treat-
ment system(s) employed.
                                                      Figure 1
                                     Schematic Diagram of Thermal Desorption
                                                                               Clean Offgas
                                                                     Gas Treatment
                                                                       System
                                                                         (3)
                                                                   r
              itment I
              »m   1^


              I—*~  Cone
Spent
Carbon





Mat
Han<
d

anal
>
	 hk-
h-

Desorption
(2)


•I I
f

\
Tre
                    Concentrated Contaminants

                    Water
                                                                       Medium
Engineering Bulletin: Thermal Desorption Treatment

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Process Residuals

    Operation of thermal desorption systems typically cre-
ates  up to six  process residual streams:  treated medium,
oversized medium rejects, condensed contaminants and wa-
ter, paniculate control system dust, clean  offgas, and spent
carbon (if used). Treated medium, debris, and oversized
rejects may be suitable for return onsite.

    Condensed water may be used as a dust suppressant for
the treated medium.  Scrubber purge water can be purified
and  returned to the site wastewater treatment facility (if
available), disposed to the sewer [3, p. 8] [8, p. 2] [4, p. 2], or
used for rehumidification and cooling of the hot, dusty me-
dia.   Concentrated,  condensed organic contaminants are
containerized for further treatment or recovery.

    Dust collected from particulate control devices may be
combined with the treated medium or, depending on analy-
ses for carryover contamination, recycled  through  the  des-
orption unit.

    Clean offgas is released to the atmosphere. If used, spent
carbon may be recycled by the original supplier or other such
processor.

Site Requirements

    Thermal desorption systems are transported typically on
specifically adapted flatbed semitrailers.  Since most systems
consist of three components (desorber, particulate control,
and gas treatment), space requirements on site are typically
less than 50 feet by 150 feet, exclusive of materials handling
and decontamination  areas.

    Standard 440V, three-phase electrical  service is needed.
Water must be  available at the site. The  quantity of water
needed is vendor and site specific.

    Treatment of contaminated soils or other waste materials
require that a site safety plan be developed to provide for
personnel protection and special handling measures. Storage
should be provided to hold the process product streams until
they have been tested to determine their acceptability for
disposal or release. Depending upon the  site, a  method to
store waste that has  been prepared for treatment may be
necessary.  Storage capacity will depend on waste volume.
    Onsite analytical equipment capable of determining site-
specific organic compounds for performance assessment make
the operation more efficient and provide better information
for process control.
Performance Data

    Several thermal desorption vendors report performance
data for  their respective systems ranging from laboratory
treatability studies to  full-scale operation at designated
Superfund sites [17][9][18].  The quality of this information
has not been determined.   These data are  included as a
general guideline to the performance of thermal desorption
equipment, and may not be directly transferrable to a specific
Superfund site.  Good  site characterization and treatability
studies are essential in further  refining and  screening the
thermal desorption technology.

    Chem Waste Management's (CWM's) X*TRAX™ System
has been tested at laboratory and pilot scale. Pilot tests were
performed at CWM's Kettleman Hills facility  in  California.
Twenty tons  of  PCB- and organic-contaminated  soils were
processed through the  5  TPD pilot system. Tables 3 and 4
present the  results of  PCB separation  from  soil and total
hydrocarbon  emissions from the system, respectively [4].

    During a non-Superfund project for the Department of
Defense, thermal desorption was used in a full-scale demon-
stration at the Tinker Air Force Base in Oklahoma. The success
of this project led to the patenting of the process by Weston
Services,  Inc.   Since then, Weston has applied its low-tem-
perature thermal treatment (LT3) system to various contami-
nated  soils at bench-scale through full-scale projects [19].
Table 5 presents a synopsis of system  and performance data
for a full-scale treatment of soil contaminated with No. 2 fuel
oil and gasoline at a site in Illinois.

    Canonie  Environmental has extensive performance data
for its Low Temperature Thermal Aeration (LTTASM) system at
full-scale operation (15-20 cu. yds. per hour). The LTTASM has
been  applied at the McKin (Maine), Ottati and Coss (New
Hampshire) and Cannon  Engineering  Corp. (Massachusetts)
Superfund sites.  Additionally, the LTTASM has been used at
the privately-funded site in South Kearney (New jersey). Table
                        Table 3
                PCB Contaminated Soils
                   Pilot X*TRAX™[4}
Matrix
Clay
Silly Clay
Clay
Sandy
Clay
Feed
(ppm)
5,000
2,800
1,600
1,480
630
Product
(ppm)
24
19
4.8
8.7
17
Removal
(%)
99.3
99.5
99.7
99.1
97.3
                        Table 4
                     Pilot X*TRAX™
            TSCA Testing - Vent Emissions [4]
Total Hydrocarbons
(ppm-V)
Before
Carbon
1,320
1,031
530
2,950
2,100
After
Carbon
57
72
35
170
180
Removal
(%)
95.6
93.0
93.3
94.2
91.4
VOC
(Ibs/day)
0.02
0.03
0.01
0.07
0.08
PCB*
(mg/m 3)
<0.00056
<0.00055
<0.00051
<0.00058
<0.00052
                                                                *Note:  OSHA permits 0.50 mg/m3 PCB (1254) for 8-hr
                                                                  exposure.
                                                       Engineering Bulletin: Thermal Desorption Treatment

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6 presents a summary of Canonic LTTASM data [5]. The Can-
non Engineering (Mass) site, which was not included in Table
6, successfully treated a total of 11,330 tons of soil, containing
approximately 1803 Ibs. of VOC [20].

    T.D.I. Services, Inc. has demonstrated its HT-5 Thermal
Distillation Process at pilot- and full-scale for a variety of RCRA-
listed and other wastes that were prepared to simulate Ameri-
can Petroleum Institute (API)  refinery sludge [8].  The com-
pany has conducted pilot- and full-scale testing with the API
sludge to demonstrate the system's ability to meet Land Ban
Disposal requirements for K048 through K052 wastes.  Inde-
pendent evaluation by Law Environmental confirms that the
requirements  were met, except for TCLP levels of nickel,
which were blamed on a need to "wear-in" the HT-5 system
[21, p- ii].

    Remediation Technologies,  Inc. (ReTec) has performed
numerous tests on RCRA-listed petroleum refinery wastes.
Table 7 presents results from treatment of refinery vacuum
                       Table 5
            Full-Scale Performance Results
                for the LT3 System [19]
                       Table 6
            Summary Results of the LTTASM
              Full-Scale Cleanup Tests [5]
Soil Range Treated Range
Contaminant (ppb) (ppb)
Benzene 1 000
Toluene 24000
Xylene 1 1 0000
Ethyl benzene 20000
Napthalene 4900
Carcinogenic
Priority PNAs <6000
Non-carcinogenic
Priority PNAs 890-6000
Table 7
5.2
5.2
4.8
<330

<330-590

<330-450

Range of
Removal
Efficiency
99.5
99.9
>99.9
99.9
>99.3

<90.2-94.5

<62.9-94.5



Contam- Soil
Site Processed inont (ppf)
S.Kearney 16000 tons VOCs 177.0 (avg.)
PAHs 35.31 (avg.)
McKin >9500cuyds VOCs ND-3310
2000 cu yds PAHs
Ottati & 4500 cu yds VOCs 1500 (avg.)
Goss




Table 8
Treated
(ppm)
0.87 (avg.)
10.1 (avg.)
ND-0.04
<0.2 (avg.)





ReTec Treatment Results-Refinery ReTec Treatment Results-Creosote
Vacuum Filter Cake (A) [3]
I
Original
Sample
Compound (ppm)
Naphthalene <0.1
Acenaphthylene <0.1
Acenaphthene <0.1
Fluorene 10.49
Phenanthrene 46.50
Anthracene 9.80
Fluoranthrene 73.94
Pyrene 158.37
Benzo(b)anthracene 56.33
Chrysene 64.71
Benzo(b)fluoranthene 105.06
Benzo(k)fluoranthene 225.37
Benzo(a)pyrene 1 74.58
Dibenz(ab)antracene 477.44
Benzo(ghi)perylene 163.53
lndeno(1 23-cd)pyrene 122.27
Treatment Temperature: 450°F

Treated
Sample
(ppm)
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
1.43
<0.1
2.17
3.64
1.89
10.25
5.09
4.16


Removal
Efficiency
...
...
...
>98.9
>99.3
>96.6
>99.8
>99.9
97.5
>99.9
97.9
98.4
98.9
97.8
96.6
96.6


Contaminated Clay [3]

Original Treated Removal
Sample Sample Efficiency
Compound (ppm) (ppm) (%)
















Naphthalene 1 321 <0.1
Acenaphthylene <0.1 <0.1
Acenaphthene 293 <0.1
Fluorene 297 <0.1
Phenanthrene 409 1 .6
Anthracene 113 <0.1
Fluoranthrene 553 1.5
Pyrene 495 2.0
Benzo(b)anthracene 59 <0.1
Chrysene 46 <0.1
Benzo(b)fluoranthene 1 4 2.5
Benzo(k)fluoranthene 14 <0.1
Benzo(a)pyrene 15 <0.1
Dibenzo(ab)anthracene <0.1 <0.1
Benzo(ghi)perylene 7 <0.1
lndeno(123-cd)pyrene 3 <0.1
>99.9
—
>99.96
>99.96
99.6
>99.7
99.7
99.6
>99.99
>99.8
82.3
>99.8
>99.9
...
>99.4
>99.3
Treatment Temperature: 500°F

Engineering Bulletin:  Thermal Desorption Treatment

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                       Table 9
           ReTec Treatment Results-Coal Tar
                Contaminated Soils [3]
Compound
Benzene
Toluene
Ethylbenzene
Xylenes
Naphthalene
Fluorene
Phenanthrene
Anthracene
Fluoranthrene
Pyrene
Benzo(b)anthracene
Chrysene
Benzo(b)fluoranthene
Benzo(k)fluoranthene
Benzo(a)pyrene
Benzo(ghi)perylene
lndeno(1 23-cd)pyrene
Original
Sample
(ppm)
1.7
2.3
1.6
6.3
367
114
223
112
214
110
56
58
45
35
47
24
27
Treated
Sample
(ppm)
<0.1
<0.1
<0.1
<0.3
<1.7
<0.2
18
7.0
15
11
<1.4
3.7
<1.4
<2.1
<0.9
<1.1
<6.2
Removal
Efficiency
(%)
>94
>95
>93
>95
>99
>99
91.9
93.8
93.0
90.0
>97
93.6
>97
>94
>98
>95
>77
I  Treatment Temperature: 450°F
filter cake.  Tests with creosote-contaminated clay and coal
tar-contaminated soils showed significant removal efficiencies
(Tables 8 and 9).  All data were obtained through  use  of
ReTec's 100 Ib/h pilot scale unit processing actual industrial
process wastes [3].

    Recycling Sciences International, Inc. (formerly American
Toxic Disposal, Inc.) has tested its Desorption and Vaporiza-
tion Extraction System (DAVES), formerly called the Vaporiza-
tion  Extraction System  (VES), at Waukegan Harbor, Illinois.
The pilot-scale test demonstrated PCB removal from material
containing  up to 250 parts per million (ppm) to levels less
than 2 ppm [12].

    RCRA LDRs that require treatment of wastes to best dem-
onstrated available technology (BOAT) levels  prior to  land
disposal may sometimes be determined to be applicable  or
relevant and appropriate requirements for CERCLA response
actions.  Thermal desorption 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 re-
quired treatment levels is dependent upon the specific waste
constituents and the  waste matrix.  In cases where thermal
desorption  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.
Treatability variances are justified for  handling complex soil
and debris matrices. The following guides describe when 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, September 1990) [10], and Superfund LDR Guide
#6B, "Obtaining a Soil and Debris  Treatability Variance for
Removal Actions" (OSWER Directive 9347.3-06BFS, Septem-
ber 1990) [11].   Another  approach could be to use other
treatment techniques  in series with thermal desorption  to
obtain desired treatment levels.

Technology Status

    Significant theoretical  research is ongoing [22][23],  as
well as direct demonstration of thermal desorption through
both treatability testing and full-scale cleanups.

    A successful pilot-scale demonstration of Japanese soils
"roasting" was conducted in 1980 for the recovery of mercury
from highly contaminated (up to 15.6 percent) soils at a plant
site in  Tokyo.  The high  concentration of mercury made
recovery and refinement to  commercial grade (less than 99.99
percent purity) economically feasible [24].

    In this country, thermal desorption technologies  are the
selected remedies for one or more operable units at fourteen
Superfund sites.   Table 10 lists each site's location, primary
contaminants, and present status [1][2].

    Most of the hardware components of thermal desorption
are available off the shelf and represent no significant problem
of availability.  The engineering and  configuration  of the
systems are similarly refined, such that once a system is de-
signed full-scale, little or no prototyping or redesign is required.

    On-line availability of the full-scale systems described in
this bulletin is not documented.  However, since the ex situ
system can be operated in batch mode, it is expected that
component failure can be  identified and spare components
fitted quickly for minimal downtime.

    Several vendors have documented processing costs per
ton of feed processed. The overall range varies from $80 to
$350 per ton processed  [6][4, p.  12][5][3, p. 9].  Caution is
recommended in using costs out of context because the base
year of the estimates vary.  Costs also are highly variable due
to the quantity  of waste to be processed,  term of the reme-
diation contract,  moisture content, organic constituency of
the contaminated medium, and cleanup standards to  be
achieved. Similarly, cost estimates should include such items
as preparation of Work  Plans, permitting, excavation, pro-
cessing itself, QA/QC verification  of treatment performance,
and reporting of data.
EPA Contact

    Technology-specific questions regarding thermal desorp-
tion may be directed to:
    Michael Gruenfeld
    U.S. Environmental Protection Agency
    Risk Reduction Engineering Laboratory
    Releases Control Branch
    2890 Woodbridge Ave.
    Bldg. 10(MS-104)
    Edison, NJ  08837
    FTS 340-6625 or (908) 321-6625
                                                       Engineering Bulletin:  Thermal Desorption Treatment

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                                                   Table 10
                       Superfund Sites Specifying Thermal Desorption as the Remedial Action
Site
Cannon Engineering
(Bridgewater Site)
McKin
Ottati & Goss
Wide Beach
Metaltec/Aerosystems
Caldwell Trucking
Outboard Marine/
Waukegan Harbor
Reich Farms
Re-Solve
Waldick Aerospace
Devices
Wamchem
Fulton Terminals
Stauffer Chemical
Stauffer Chemical
Location
Bridgewater, MA (1 )
McKin, ME (1)
New Hampshire (1 )
Brandt, NY (2)
Franklin Borough, N| (2)
Fairfield, N| (2)
Waukegan Harbor, IL (5)
Dover Township, NJ (02)
North Dartmouth, MA (1)
New Jersey (2)
Burton, SC (4)
Fulton, NY (2)
Cold Creek, AL (4)
Le Moyne, AL (4)
Primary Contaminants
VOCs (Benzene, TCE &
Vinyl Chloride)
VOCs (TCE, BTX)
VOCs (TCE; PCE; 1, 2-DCA,
and Benzene)
PCBs
TCE and VOCs
VOCs (TCE, PCE, and TCA)
PCBs
VOCs and Semivolatiles
PCBs
TCE and PCE
BTX and SVOCs
(Naphthalene)
VOCs (Xylene, Styrene, TCE,
Ethylbenzene, Toluene) and
some PAHs
VOCs and pesticides
VOCs and pesticides
Status
Project completed 1 0/90
Project completed 2/87
Project completed 9/89
In design
• pilot study available 5/91
In design
• remedial design complete
• remediation starting Fall '91
In design
In design
• treatability studies complete
Pre-design
In design
• pilot study |une/)uly '91
In design
In design
• pilot study available 5/91
Pre-design
Pre-design
Pre-design
Acknowledgements

    This bulletin was prepared for the U.S.  Environmental
Protection  Agency,  Office  of  Research and Development
(ORD), Risk Reduction Engineering Laboratory (RREL), Cin-
cinnati, Ohio, by Science Applications International Corpora-
tion (SAIC) under contract no. 68-C8-0062. Mr.  Eugene
Harris served as the EPA Technical Project Monitor. Mr. Gary
Baker (SAIC) was the Work Assignment Manager and author
of this bulletin.  The author is especially grateful to Mr. Don
Oberacker, Ms. Pat Lafornava, and Mr. Paul de Percin of EPA,
RREL, who  have contributed significantly by serving as tech-
nical consultants during the development of this document.
    The following other Agency  and contractor  personnel
have contributed their time and comments by participating in
the expert review meetings and/or peer reviewing  the docu-
ment:
   Dr. James Cudahy
   Mr. James Cummings
   Dr. Steve Lanier
                         Focus Environmental, Inc.
                         EPA-OERR
                         Energy and Environmental
                         Research Corp.
Ms. Evelyn Meagher-Hartzell SAIC
Mr. James Rawe            SAIC
Ms. Tish Zimmerman       EPA-OERR
Engineering Bulletin: Thermal Desorption Treatment

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 8
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