v-/EPA
                                    United States
                                    Environmental Protection
                                    Agency
                 EPA/540/MR-94/507
                 April 1994
                                   SUPERFUND INNOVATIVE
                                   TECHNOLOGY EVALUATION
                                    Demonstration Bulletin
                                                               I
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                                      Thermal Desorpticn System

                                            Clean Berkshires, Inc.
Technology Description:  A thermal desorption system
(TDS) has been  developed  by Clean Berkshires,  Inc. (CBI),
Lanesboro, Massachusetts for ex-situ treatment of soils and other
media contaminated with organic pollutants. The TDS uses heat
as both a physical separation mechanism and as a means to
destroy contaminants. The process is continuous and is com-
posed of  three different  operations: feed preparation,  contami-
nant volatilization, and gas treatment.

Feed preparation begins with a sequence consisting of crushing,
shredding, and screening excavated or dredged waste material
to reduce maximum particle size to 3/4-inch.  Next, using a front-
end loader, the waste is repeatedly folded into itself in an attempt
to distribute moisture and pollutants evenly. This step is particu-
larly important since it helps protect the system  from severe,
sudden thermal shocks caused by "hot spots" in the waste. The
prepared material is then dumped into surge bins and fed into a
kiln through a two-stage conveyor belt system.

Contaminant  volatilization begins after the prepared material en-
ters the kiln.   The temperature of the  soil is increased through
contact with an air stream heated by a natural gas burner located
at the entrance of the kiln. The kiln is equipped with  specially
designed  flights which lift  and veil the  soil, exposing greater
surface area  to the hot gases, improving volatilization.  Treated
soil exits  the kiln and enters a pug mill which  combines the
material with  solid residuals from gas treatment.  Water recycled
from the quench tower is added at this time to cool  the treated
materials and to control fugitive dust emissions.  The solids are
deposited onto a discharge conveyor and stockpiled.

Gas treatment begins when the gas stream from the kiln, which
contains volatilized contaminants and entrained paniculate, en-
ters a multi-stage treatment sequence. The sequence  uses the
following:  a cyclone to remove  coarse particulate,  a  high-effi-
ciency afterburner to destroy organics, a quench tower to cool
the gas stream, and a baghouse to remove filterable particulate
still suspended in the gas stream. A scrubber could be  added to
remove sulfur dioxide if levels are high  enough  to impact air
quality standards. Treated gases exit the system through a 75-
foot high  stack.  Solid residuals from  gas treatment are trans-
ferred by  a screw auger to the pug mill and are combined with
the treated waste material.

The TDS is transportable and is monitored and controlled by a
computer-based data acquisition system.
Waste Applicability:  The  CBI TDS process  has been
successfully applied at two sites processing soils from throughout
New England and New York. To date, over 250,000 tons of solid
wastes have been treated using this technology.  The CBI TDS
can  remove volatile  organic compounds (VOCs), semivolatile
organic compounds (SVOCs), organometallic complexes, and
total petroleum hydrocarbons (TPHs).  Full-scale CBI TDS opera-
tions] have been used to remove VOCs such as  benzene, tolu-
ene, ethylbenzene, and xylene (BTEX); SVOCs such as naphtha-
lene, phenanthrene, chrysene, benzo(a)pyrene, and other poly-
nuclear aromatic hydrocarbons (PAHs); organometallic complexes
such; as  ferricyanides; and TPHs in  the  range  of  C4
toC,'.
Demonstration  Results:  The CBI  TDS  Demonstration
took place at the Niagara Mohawk Power Corporation's Reme-
diation Technologies Demonstration Facility at Harbor Point in
Uticaj New York between November 15 and December 13,1993.
Figure 1 is a photo of the TDS used at this site.  Harbor Point is
the site of a former manufactured gas plant (MGP) and is con-
taminated with BTEX and PAHs, ferricyanide compounds, and a
variety of  heavy metals.   Four different types  of  MGP  solid
wastes were tested: (1) coke plant residuals; (2) purifier wastes;
(3)  water gas plant residuals; and (4) Utica Terminal Harbor
sediments.  Maximum pollutant concentrations were 320 milli-
grams per kilogram (mg/kg) BTEX; 3500 mg/kg PAHs; 1200 mg/
kg cyanide; 60 mg/kg arsenic; and 320 mg/kg lead.

Three 4-hr replicate runs were conducted for each waste type.
For each run, samples were collected from feed soil, treated  soil,
cyclone solids, baghouse solids, quench water, intake water, and
stack gases. Samples were analyzed for PAHs, BTEX, cyanide
and metals.  Feed  soil samples were also analyzed for other
chemical and geotechnical parameters.

Critical operating parameters were optimized and monitored for
each {waste type.  Soil  feed rate and kiln soil exit temperature
were varied for each waste stream, based on preliminary results
from an experimental test phase. The range for each parameter
was as follows: feed rate, 16 to 22 tons per hour; kiln soil exit
temperature, 620 to 860 °F; afterburner residence time, 0.82 to
0.87 seconds; and afterburner temperature,  1810 to 1820°F.
                                                                                              Printed on Recycled Paper

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                                    Hgure 7. Ctean Berkshlres, Inc. Thermal Desorption System
Preliminary results from the SITE Demonstration are summarized
below:                                              *

    • The CBITDS achieved DREs of 99.99 percent or better in
      alt 12 runs using total xylenes as a volatile principal  or-
      ganic hazardous constituent (POHC).

    * DREs of 99.99 percent or better were achieved in 11 of 12
      runs using naphthalene as a semivolatile POHC.

    * Average concentrations  for critical pollutants in  treated
      soils were 0.066 mg/kg, BTEX; 12.4 mg/kg, PAHs; and 5.4
      mg/kg total cyanide.

    • Comparison of the dry weight basis concentration of pollut-
      ants  in the feed and  treated soil showed the following
       average removal efficiencies:  99.8  percent, BTEX; 986
       percent, PAHs; and 97.4 percent total cyanides.
        ""' >  ' "  ..... n" "" ' ' ' "   " . J i  '     "    " ' ' '  '   ' '    ' ' '      !  ' ' ' ' '
                            ' n v !» ...... I" 5 !, , t  "SI ' pi ' . 'i . ...... ' ii* f
     • The CBI TDS showed good operating stability during the
       Demonstration with only a minor amount of down time.

 An Innovative technoiogyEvaiuatiori Report describing the com-
 plete Demonstration will be available in the Fall of 1994.

 For Further Information:
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 EPA Project Manager
 Ronald F. Lewis
 U.S Environmenta.1 Protection Agency
 Risk Reduction Engineering Laboratory
 26 W. Martin Luther King Drive
 Cincinnati, OH 45268
 (513) 569-7856          -u.S. Government Printing Office: 1994— 650-067/80267
    United States
    Environmental Protection Agency
    Center for Environmental Research Information
    Cincinnati, OH 45268

    Official Business
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                                PERMIT No. G-35
    EPA/540/MR-94/507

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