United States
Environmental Protection
Agency
EPA/540/MR-93/5Q4
March 1993
vvEPA
SUPERFUND INNOVATIVE
TECHNOLOGY EVALUATION
Demonstration; Bulletin
° i
).
Low Temperature Thermal Aeration (LTTA®) Process
Canonie Environmental Services, Inc.
Technology Description: The Low Temperature Thermal Aeration
(LTTA®) process was developed by Canonie Environmental Services, Inc.
(Canonie), as a treatment system that desorbs organic contaminants from
soils by heating the soils up to 800 °F. The main components of the LTTA*
process include the following: (1) a materials dryer, (2) a pug mill, (3) two
cyclonic separators, (4) a baghouse, (5) a wet Venturi scrubber, (6) a
' Squid-phase granular activated carbon (GAG) column, and (7) two vapor-
phase GAC beds (see figure 1).
A front-end loader transports contaminated soils to feed hoppers, which
release the soil onto a conveyor bet The conveyor belt transports "the
contaminated soils into the materials dryer. Contaminated soils in the
materials dryer are heated by a parallel-flow hot air stream heated by a
propane/fuel oil burner. The materials dryer is a rotating drum 8 ft in
diameter and 40 ft long equipped with longitudinal flights for soil mixing.
Processed soil is discharged to an enclosed pug mill, where water is
added to cool it and to control fugitive dust emissions. Treated soil is
released onto a discharge conveyor and stodpled. The stockpiled soil is
tested onsite to confirm that the treated soil meets clean-up goals and then
disposed of onsite or recreated, as required.
Thel exhaust air stream from the materials dryer, containing vaporized
organic contaminants and airborne soil particulates, is treated with a series
of standard air pollution control devices before being vented to the
atmosphere. The exhaust air stream is first vented into two cyclonic
separators operating in parallel to remove coarse particulates. The ex-
haust air stream from the cyclonic separators is then directed to a
baghouse that removes the remaining coarse particulates. The particu-
lates collected at the base of the cyclonic separators and at the baghouse
are transferred by a screw auger to the pug mill, where they are incorpo-
rated into the treated soil.
Following removal of coarse particulates, the exhaust air stream is directed
to a wet Venturi scrubber that (1) removes fine particulates, (2) neutralizes
acid vapors, and (3) removes any water-soluble organic contaminants.
Sodium hydroxide is added as needed to the scrubber liquor to maintain a
system pH above 7.0. Scrubber blowdown is treated by a liquid-phase
GAC column before being used as quench water in the pug mill; no
scrubber wastewater is discharged from the process.
The > final portion of the air pollution control system includes two vapor-
phsse GAC beds operating in parallel that remove any remaining organic
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Figure 1. LTTA9 soil processing equipment layout
Printed on Recycled Paper
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contaminants. The treated exhaust air stream is then vented to the
Waste Applicability: The LTTA* process has remediated contami-
nated sells st six sites including three Superfund sites. More than 90,000
tons of goi have been treated by the LTTA* process. The LTTA* process
can remove voJatle organic compounds (VOC), semh/otatite organic com-
pounds (SVOG), organochlorhe pesticides (OOP), organophosphorous
pestteldes (OPP), and total petroieum hydrocarbons (TPH) from soife,
sediments, and sludges. FuB-scate LTTA9 operations has/a been used to
remove VOCs such as benzene, toluene, tetrachloroethene (PCE),
Ufchferoethono (ICE), and dichbroethene (DCE); SVOCs such as
acanapntheno, chrysone, naphthalene, and pyrene; OCPs such as tox-
aphorvQ and dichbrodiphenyltrichbroethane (DDT) and its metabolites;
OPPs such as ethyl parathfon and methyl parathbn; and TPHs. Canonie
reports removal efficiencies of greater than 99% for VOCs at concentra-
tions up to 5,400 mffigrams per kilogram (mg/kg), greater than 92% for
p&stfcoes up to 1,500 mg/kg, and 67 to 96% for SVOCs up to 6.5 mg/kg.
Tha LTTA* process is best suSed for dry granular sofe, however soils
containing sit and day have been successfully treated, and sludges are
potentially treatable by the LTTA* process.
Demonstration Results: The LTTA* demonstratbn was conducted in
September, 1992, as part of ongoing remediation of a pesticide-contami-
nated ste in western Arizona. Soils at tie site had been impacted with
toxapbena, DDT, its derivatives ODD and DDE as well as other pesticides.
Feod ad consisted of a dry, clayey bam that was preheated by removing
largo cobble-sized particles with a vibrating screen prior to entry into the
feed hopper. Sofe were heated to 730 °F. A feed rate ranging between 34
and 33 tons/tir was utized during the demonstratbn.
Throe 8-hr repicato test runs were conducted. For each run, samples of
intake water, feed sol, treated soil, Venturi scrubber liquor, treated scrubber
iquor, stock gas emissions, and the vapor-phase GAG beds were col-
lected, Sofci, liquid, and gas samples were analyzed for pesticides, VOCs,
SVOCs, dfoxins, and furans. To quaSatively trace the fate of chloride
through the system, samples were analyzed for chbride and total organic
haSdos. A variety of other parameters were also analyzed to characterize
the food and treated sol Key findings from tie SITE demonstratbn are
summarized below:
• TbeLTTA*processmetth0speciiedcteanupcrteiTaf^
scale criteria correlating the concentratbns of DDT family compounds
(ODD, DDE,arxiDDT)wiicc)ncertrationsoftoxaphene.Themaxirnum
•U.S. Oovwnmtol Priming Otfc»: 1993— 750-071/80103
allowable pesticide concentratbns In the treated soil were 3.52 mg/kg
of DDT family compounds and 1.09 mg/kg of toxaphena
Residual levels of all the pesticides in the treated soil were generally
bebwordosetbthe laboratory detection limit, with the exceptbnof 4,4-
DDE which was found at residual concentratbns of 0.1 to 1.5 rng/kg.
Removal efficiencies for pesticides found in the feed soil at quantifiable
concentrations are summarized below:
Compound
4,4'-DDD
4,4'-DDE
4,4'-DDT
Endrin
Toxaphene
Endosutfan I
>99.97%
9026%
99.97%
>99.85%
>99.83%
>99.98%
The LTTA8 process old not generate dioxins-orfurans as products of
incomplete combustion or thermal transformation.
Some thermal breakdown products were formed within the LTTA8
process, which mainly included acetone, acrybn'rtrile, benzob acid,
benzyl alcohol, benzaldehyde, dihydrofuranone, phenol, and methyl
phenol These products were extensively removed hi the untreated
scrubber liquor and the vapor-phase GAC beds. The stack emissions
included some of the compounds at bw concentrations.
The average emissions rate for compounds detected at quantifiable
levels in the stack gas included 4,4-DDE at 0.000043 plb/hr,
chbromethane at 0.020 b/rir, benzene at 0.053 b/hr, and toluene at
0.008 b/hr. The presence of acetonMe and acrytonitrile in the stack
emissions are currently being confirmed.
The LTTA® process performed efficiently with no down time during the
denranstrBtbn,Astaffd6to8terequiredtoopeiatetheLTTA*process,
including site supervisors, an excavation crew, support staff, and
laboratory chemists for next day confirmatbn testing. The LTTA*
process layout requires space for eight to 10 flat-bed trailers and
sufficiert area (150'x 150') to stage feed arid treated soils.
For Further Information:
EPA Project Manager.
Paul R. dePercin
U.S. EPA Risk Reduction Engineering Laboratory
26 West Martin Luther King Drive
Cincinnati, OH 45268
(513)569-7797; FAX (513) 569-7620
United States
Environmental Protection Agency
Center for Environmental Research Information
Cincinnati, OH 45268
Official Business
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EPA
PERMIT No. G-35
EPA/540/MR-93/504
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