United States
Environmental Protection
Agency
Hazardous Waste Engineering
Research Laboratory
Cincinnati OH 45268
Research and Development
EPA/600/S2-87/033 June 1987
Project Summary
Destruction of Dioxin-
Contaminated Solids and
Liquids by Mobile Incineration
Helge Mortensen, Alan Sherman, William Troxler, Richard Miller, and
Charles Pfrommer
The EPA Mobile Incineration System,
which consists of a kiln, secondary
combustion chamber, air pollution
control unit, and separate continuous
stack gas analysis capabilities, was
rigorously tested in 1982-1983 using
PCB-contaminated liquids and other
chlorinated organic fluids. Destruction
and removal efficiencies of at least
99.9999% were consistently attained
at a heat release of 10 GJ/hr.
As a result of these favorable
performance data, a project was
initiated to evaluate the technical,
economic, and administrative feasibil-
ity of on-site incineration of dioxin-
contaminated materials. During 1984,
the system was extensively modified
for field use and performance-tested
with a variety of uncontaminated soils
and other solid wastes at the EPA
facility in Edison, NJ.
Based on the results of laboratory and
pilot plant studies conducted to estab-
lish optimum kiln conditions and the
available literature, the EPA system
was judged to be more than adequate
for detoxifying dioxin-contaminated
solids and liquids, and thus could be
expected to accomplish a successful
dioxin trial burn. Accordingly the
system was transported in December
1984 to the Denney Farm site in
McDowell, Missouri, which had been
selected for the trial burn in the inter-
vening months.
Destruction and removal efficiencies
exceeding 99.9999% were achieved
for 2,3,7,8-TCDD during a trial burn
on dioxin-contaminated liquids and
solids conducted in April 1985. The kiln
ash and process wastewater by-
products had no detectable dioxins and
were in accordance with guidelines
identified by EPA's Office of Solid
Waste.
A field demonstration on a variety of
dioxin-contaminated materials was
conducted between July 1985 and
February 1986. A total of 0.9 million
kg of solids and 81,600 kg of liquids
was successfully decontaminated dur-
ing that time. Operations were sus-
pended on February 6, 1986 pending
Superfund reauthorization. When oper-
ations resume, the Field Demonstration
will be completed and a second trial
burn will take place on materials
designated by the Resource Conserva-
tion and Recovery Act and the Toxic
Substances Control Act.
This Project Summary was deve-
loped by EPA's Hazardous Waste
Engineering Research Laboratory, Cin-
cinnati, OH, to announce key findings
of the research project that is fully
documented in a separate report of the
same title (see Project Report ordering
information at back).
Introduction
The continued discovery of abandoned
hazardous waste sites by Superfund
investigations, decreasing availability of
landfill sites, and increasing public
opposition to toxic and hazardous waste
transport have placed increasing pres-
sure on the U.S. Environmental Protec-
tion Agency (EPA) to find alternatives for
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treating and disposing of toxic and
hazardous wastes. The treatment and
disposal problem is particularly acute in
the case of the highly toxic dioxin isomer
2,3,7,8-tetrachlorodibenzodioxin
(2,3,7,8-TCDD). In recognition of these
difficulties and as a result of preliminary
favorable tests of the technology, EPA's
"Dioxin Strategy" (November 28, 1983)
recommended that high-temperature
incineration of dioxin-contaminated
materials be evaluated further by the
Office of Research and Development
(ORD).
The EPA Mobile Incineration System
(MIS) was designed and constructed for
ORD to provide such treatment at the
actual site of dioxin contamination. The
system consists of a refractory-lined
rotary kiln, a secondary combustion
chamber (SCC), and air pollution control
equipment mounted on three heavy-duty
semi-trailers. Monitoring equipment is
carried by a fourth trailer. The ability of
the MIS to destroy tetrachloromethane
(carbon tetrachloride), dichlorobenzene,
trichlorobenzenes, tetrachlorobenzenes,
and PCBs while complying with applica-
ble Federal and State regulations for the
emissions of HCI and particulate matter
was demonstrated during a Liquid Trial
Burn conducted between September
1982 and January 1983 at the EPA
facility in Edison, NJ.
In March 1984, the ORD Releases
Control Branch (RGB) of the Hazardous
Waste Engineering Research Laboratory
(HWERL), at the request of the EPA
Region VII, embarked on a field validation
project to evaluate the MIS for on-site
treatment and disposal of toxic and
hazardous wastes, particularly soils
contaminated with 2,3,7,8-TCDD. The
purpose of this research was to deter-
mine the economic feasibility of the
technique and to establish: (1) test burn
protocols; (2) health and safety protocol;
(3) site specific, risk assessment protocol;
(4) an economic model for estimating the
cost of treatment per unit of material
processes; and (5) national and state
permit protocol.
Site Selection and Planning
Agreements were reached in April
1984 to operate the Mobile Incineration
System on the Denney Farm near McDo-
well, MO, where over 90 drums of dioxin-
contaminated wastes had been exca-
vated and stored in a diked shelter. A
second covered concrete basin on the
site contained over 180 m3 of soil that
had become contaminated when the
buried drums leaked.
The Denney Farm was chosen in part
because the safe removal and destruc-
tion of dioxin that contaminated soil,
liquids, drums, trash, and chemical solids
on the site would demonstrate the
versatility of the MIS. Further, the variety
of soil types available in the immediate
area would demonstrate that incinera-
tion could decontaminate dioxin-
containing soil found elsewhere in
Missouri.
Laboratory and Pilot Studies
These studies, performed concurrently
with the Federal and State permitting
processes, investigated whether the
objective of decontaminating the soil to
less than 1 ppb dioxin was feasible given
the operating limits of the MIS, and to
develop recommended operating condi-
tions for the trial burn and field
demonstration.
Soils from two Missouri sites with
confirmed dioxin contamination were
selected for laboratory treatability test-
ing. The average 2,3,7,8-TCDD concen-
trations were relatively high in both soils
(563 ppb in Denney Farm soils; 338 ppb
in Piazza Road soils), enabling investi-
gation of the maximum treatability range.
In addition, soils from both sites had wide
ranges of pH, conductivity, organic
matter content, and particle size
distributions.
Three series of treatability tests were
conducted. The first determined the
optimal kiln residence time and temper-
ature that would produce the target
treatment effectiveness of 1 ppb or less
of 2,3,7,8-TCDD residue. The second
series characterized the effect of soil type
(Piazza or Denney), initial soil mositure
content, and gas phase composition on
treatability under fixed residence time
and temperature conditions. The third
series included additional treatment
conditions to fill in data gaps and also
several special tests in which 5-cm
"cubes" (to simulate clay lumps) of
Piazza Road soil were tested under
various conditions.
A linear regression analysis of the
treatability data for Denney farm soil
allowed prediction of the final 2,3,7,8-
TCDD concentrations at different time-
temperature conditions as shown in
Figure 1 and Table 1. There was no
significant correlation between soil
treatability and either moisture or atmos-
phere; soil type had a relatively minor
influence.
In the third series of tests, a substant
lag in achieving the target test tempe
ature within a cube core was attribut
largely to the drying process. The eva
oration rate of the initial 20% moistu
content from the cube was dependent i
the heat and mass transfer character!
tics of the cube and the external g
temperature, which in the MIS kiln wou
be higher than 500°C.
The results from the laboratory testii
demonstrated that the clean-up criterii
of 1 ppb could be achieved at reasonab
kiln operating conditions and provid
part of the information needed to proj€
the specific kiln residence time ai
temperature for various feed rates a
feed conditions for the MIS.
Modifications to the MIS
Several changes were made in t
original MIS design, including genei
modifications affecting the refractoi
the burner controls; the stack g
monitoring system; the electrical syste
and the design, specification, procur
ment, installation, and shakedown of
solids feed system.
Further design modifications, inclu
ing a wet electrostatic precipitator, a
planned.
Site Preparation and
Community Relations
After selection of the Denney Farm 1
the MIS demonstration, detailed eni
neering and design were started
satisfy operating and permitting requir
ments. The actual incinerator site w
determined by the physical dimensio
of the solids feed handling system a
the location of the contaminated mat
rials in a prefabricated metal buildir
Further site contamination was pi
vented by maintaining the incinerator
an uncontaminated area and the fe
system in a contaminated area with
connecting sealed conveyor system.
After several changes in the origir
design and hot and cold shakedown tes
to ensure reliable operation, the MIS w
transported to and set up on the Denn
Farm site in mid-December 1984.
Field Shakedown and Trial
Burn
Final preparations, component chec!
and on-site personnel safety traini
were completed by early January 19E
The incineration system was then start
up with fuel oil to check its performan
after transport from New Jerse
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900
800
700.
600-
5OO-
400-
300.
Residual Concentration of 2,3,7.8- TCDD
0.1 ppb
~- -
Ijipb
10 ppb
0 10 20 30 40 SO 60 70
Time Required (Minutest
Figure 1. Effect of time and temperature on removal of 2.3.7,8- TCDD from Denney Farm soil.
80
90
100
Mechanical and weather-related prob-
lems delayed the start of the Trial Burn.
Dioxin-contaminated liquids and solids
were fed to the incinerator for the first
time at the end of February. Several more
minor problems were encountered and
corrected, and by April 1985, four dioxin
trial burn runs had been completed.
Trial Burn Plan
The trial burn program was originally
designed to consist of three tests.
However, due to the operational prob-
lems noted above. Test 1, a burn using
a PCB matrix mixed with 5 wt % hex-
achloroethane to achieve a 5% PCB
concentration and liquid tetrachlorome-
thane, was postponed to the end of the
field demonstration. The two tests that
were performed are described below.
Test 2
2,3,7,8-TCDD (dioxin)-contaminated
soil and dioxin-containing waste liquids
(primarily trichlorophenol in a solvent
mix of methylene chloride and butanol)
were fed to the rotary kiln to demonstrate
the ability of the MIS to destroy dioxin
with a destruction and removal efficiency
(DRE) of 99.9999%.
Test3
Bromine-contaminated industrial
chemical sludge was fed to the rotary kiln
to demonstrate the ability of the MIS to
control bromine/hydrogen bromide
emissions while incinerating bromine-
contaminated wastes.
The Quality Assurance Project Plan
(QAPP) for the Trial Burn ensured that
the trial burn data were technically sound
and acceptable to regulatory offices.
Standard analytical protocols were used
whenever possible, but the determina-
tion of 2,3,7,8-TCDD in incinerator
emissions and by-products required
state-of-the-art analyses to demonstrate
the required DRE. The samples were
analyzed in two laboratories to provide
independent verification of test results.
The incinerator operating conditions
during the Dioxin Trial Burn were essen-
tially the same as those during the
previous Liquid Trial Burn successfully
conducted in New Jersey. Waste liquids
and solids were fed to the rotary kiln.
The solids were retained in the rotary
kiln, which operated at a gas exit
temperature of 845-955°C, for approx-
imately 30 minutes before being dis-
charged at 750°C into drums. The gases
from the combustion of wastes flowed
into the SCC where they were heated
to 1150-1230°C. The combustion gases
in the SCC were mixed with excess
oxygen (air) to a control level of 4-7%
02 and were retained for 2.4-3 sec. The
relatively long retention time was due to
the operation of the incineration system
at low gas flow rates to minimize
particulate carryover from the kiln into
the SCC, not to a DRE-related
requirement.
The combustion gases then passed
through three stages of air pollution
control equipment to cool, filter, and
remove acid gases (by-products from
waste combustion) and particulate mat-
ter (from the solid wastes processed).
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Table 1. Summary of Time-Temperature Effect on Removal of 2,3,7.8-TCDD
Nominal
Test
Temperature
PC)
429
430
429
428
429
475
478
477
479
550
550
554
616
616
.. . 616
803
808
803
Time at
Test
Temperature*
(minj
0
15
30
90
90
0
15
30
30
0
0
15
0
15
30
30
30
90
Soil
Type"
A
A
A
A
B
A
A
A
A
A
A
A
A
A
A
A
B
A
Residual
2,3.7,8-TCDD
Concentration
(ppo)
377
60
30.8
10.2
2.86
67
8.4
3.7
3.37/3.30"
24
27.5
0.16
0.2
NO (0.08)
NO (0.06)
NO (0.02)
NO (0.04)
ND (0.08)
'This time begins when the target test temperature is reached; therefore, zero time is actually
six to nine minutes after start of heat-up.
"A: Denney Farm Soil; B: Reference Soil.
Analytical duplicate; separate aliquots of treated soil were analyzed.
Other process by-product streams (kiln
ash, CHEAP mat, and purge water) were
collected and analyzed in accordance
with delisting guidelines and the Trial
Burn Plan. The incinerator performance
during the trial burn was actually better
than reported since the actual emissions
were lower than what is measurable by
current sampling and analytical technol-
ogy. No 2,3,7,8-TCDD was detected in
the stack, using state-of-the-art high
resolution mass spectrometry. The low-
est ORE for 2,3,7,8-TCDD was
99.999973%; the best DRE of
99.99999% during the trial burn
occurred in Test 2, Run 4, which had the
greatest analytical sensitivity. The
results of Test 3 were also satisfactory
in that no bromine or chlorine was
detected in the stack gas.
In summary, the Trial Burn obtained
data, which, when combined with data
from the Liquid Trial Burn in Edison, NJ,
verified that (1) dioxins and other hazard-
ous organic liquid and solid materials are
destroyed by incineration in the EPA MIS
to a residual ash concentration of less
than 1 ppb, (2) by-product ash, CHEAP
media, and water met delisting stand-
ards, and (3) the resulting stack emis-
sions do not pose an unacceptable health
or safety risk to the surrounding
communities.
Field Demonstration
The objective of the field demonstra-
tion is to determine the rates at which
various types of dioxin-contaminated
liquids and solids can be fed into the
system and decontaminated. In addition,
the demonstration will result in the
cleanup of the majority of dioxin-
contaminated material in southwestern
Missouri. As of February 6, 1986, more
than 900,000 kg of solids and 81,600
kg of liquids have been incinerated.
Recommendations
The following recommendations are
the result of the experience gained
during the design, operation, and main-
tenance of the MIS Trial Burn and Field
Demonstration in Missouri. The recom-
mendations center around the need to
prepare for the following circumstances:
• extreme weather conditions
• mechanical failures
• road bed failure due to inadequate site
preparation
• unavailability of spare parts
In addition, it is recommended that the
permitting process be started as soon at
the site is chosen. The delisting protoco
required analytical tests on every tank
of wastewater and on relatively small
quantities of treated soil to confirm that
the extracts of the material met RCRA
Extraction Procedure (EP) toxicity criteria
before discharge or disposal. In retro-
spect, securing a National Pollution
Discharge Elimination System (NPDES]
permit may have allowed more efficient
site preparations and decreased analyt-
ical costs (due to. longer analytical
turnaround time) since NPDES permits
normally require less frequent sampling
and reporting of analytical results.
Economic Analysis
The unit cost ($/Mg) of waste material
processed by a mobile incinerator
strongly depends on its capacity, on-
stream factor, and the associated cost.
The capacity of the MIS results from a
complex interaction between the phys-
ical size of its components; the operating
conditions necessary to meet the DRE
and delisting requirements; and the
waste characteristics. The EPA MIS
utilizes the largest size components that
can be accommodated on semi-trailers.
Operating conditions are selected con-
servatively to process a variety of waste
materials and meet the DRE and delisting
requirements. For the specific compo-
nent sizes and operating conditions, the
capacity of the MIS was about 450 kg/
hr for 8.8 MJ/kg heating value lagoon
sludge and about 900 kg/hr for a low
heating value soil.
The MIS, being a prototype system,
experienced a low (45-55%) on-stream
factor during its operation at Missouri.
Based on the lessons learned from its
operation, a similar mobile system can
be expected to demonstrate an on-
stream factor of 70%. The costs of an
MIS can be grouped into three general
categories: capital costs, including all
costs that can be amortized over the
service life of the system; mobilization/
demobilization costs that are associated
with the startup and shutdown at a given
site and can be amortized while the unit
is located (and operated) at a given site;
and operating and maintenance costs.
Capital costs include the costs for
design and fabrication; development of
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operating procedures; providing operator
training; initial startup and shakedown;
application costs for a permit; and trial
burn costs for general performance data.
Mobilization/demobilization costs
include the costs for site preparation and
logistics; transportation and system
setup; on-site system checkout; site-
specific testing for proof-of-performance;
and decontamination and demobiliza-
tion. A review of the operating costs
during the 116 days that El was the
operating contractor (October 3, 1985 to
February 6, 1986, less the Christmas
holiday shutdown of 10 days) showed
that the MIS operating is field-labor
intensive.
A simplified economic analysis was
performed for an incineration system
designed and fabricated utilizing all the
EPA MIS data and drawings. The actual
MIS associated cost factors were used.
The capital cost of $5.1 million and
mobilization/demobilization costs of
$0.9 million were used. Site-specific cost
factors such as costs for site preparation
and logistics and system transportation
were not included.
An on-stream factor of 70% was
assumed for this analysis. Operating
costs extrapolated from the actual field
operation of 116 days were $4.2 million/
yr. Based on a 15-year system life with
equipment relocation assumed every 2
years, the unit cost of the incineration
system was calculated to vary between
$750/Mg for low heat content soil to
$1500/Mg for lagoon sludge.
The planned modifications to the
system will double its capacity, increase
the on-stream factor to 80%, increase the
capital costs by about 20%, and increrase
the mobilization/demobilization and
operating costs by about 10%. Therefore,
the unit costs for the modified system
is expected to be approximately $3607
Mg for low heat content soil and $7207
Mg for lagoon sludge.
Future Use of the MIS
Further use of the EPA MIS after the
field demonstration at Denney Farm will
be at the direction of the EPA Office of
Solid Waste and Emergency Response.
The intention of future operations of
the MIS is to encourage commercializa-
tion of on-site cleanup technologies
rather than to use the system strictly for
cleanup activities. The private sector is
likely to build improved, more reliable,
larger capacity, lower-cost systems of at
least equivalent performance for use in
routine cleanup operations.
The full report was submitted in
fulfillment of Contract Number 68-03-
3255 by Enviresponse, Inc., under the
sponsorship of the U.S. Environmental
Protection Agency. The report covers a
period from February 1984 to February
1986 and work was completed as of April
15, 1987.
H. Mortensen and A. Sherman are with Enviresponse, Inc.. Livingston NJ
07039; W. Troxler, R. Miller, and C. Pfrommer are with IT Corp.. Knoxville
TN 37923.
Frank Freestone is the EPA Project Officer (see below).
The complete report, entitled "Destruction of Dioxin-Contaminated Solids and
Liquids by Mobile Incineration." (Order No. PB 87-188 512/AS; Cost: $18.95
subject to change) will be available only from:
National Technical Information Service
5285 Port Royal Road
Springfield. VA 22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Re/eases Control Branch
Hazardous Waste Engineering Research Laboratory—Cincinnati
U.S. Environmental Protection Agency
Edison, NJ 08837
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