United States
Environmental Protection
Agency
Hazardous Waste Engineering.
Research Laboratory
Cincinnati OH 46268
Research and Development
EPA/600/S2-85/083 Dec 1985
vvEPA Project Summary
Interim Report on the
Feasibility of Using UV
Photolysis and APEG Reagent
for Treatment of Dioxin
Contaminated Soils
Charles J. Rogers, Albert J. Klee, Alfred Kernel,
James B. White, Keith B. Leese, and Andy C. Clayton
Alkali polyethylene glycolate (APEG)
was field tested at Shenandoah Stables
in Moscow Mills, Missouri, to evaluate
its potential to dechlorinate 2,3,7,8-
tetrachlorodibenzo-p-dioxin [2,3,7,8-
TCDD] under field conditions. Two tests
were scheduled for early summer 1984,
one inside the stable arena and the
other outside, in an area known as the
"slough." However, acces to the site
was delayed until fall 1984 due to diffi-
culties in obtaining the owner's ap-
proval. Because of extremely wet
weather during the fall, the outside test
was postponed until the summer of
1985.
An experimental design employing a
Latin square was used to compare five
levels of treatments. The treatments
were designated: (1) APEG-treated and
covered, (2) APEG-treated and uncov-
ered, (3) not treated and covered,
(4) not treated and uncovered, and
(5) methoxypolyethylene glycol
(MPEG) control and uncovered. In addi-
tion to the arena site, two sections of
bleachers were tested with APEG to de-
termine the ability of the chemical to
decontaminate dustcovered surfaces.
An analysis of variance was per-
formed on the sample data. It was de-
termined that there was not a statisti-
cal difference between those plots
treated with APEG and those treated
with the MPEG control. The deactiva-
tion of APEG was directly attributable
to the fact that APEG is moisture-
sensitive. In addition to the general
humidity produced by the continual
rainfall during the project, high soil
moisture was present inside the stable.
This soil moisture was determined to
be on the order of 18 to 21 percent by
water weight. The APEG has since been
determined to be extremely hygro-
scopic and capable of pulling moisture
from out of the surrounding environ-
ment, resulting in its deactivation. The
bleachers test showed approximately a
32-percent and a 16-percent reduction
in 2,3,7,8-TCDD in the final dust sam-
ples after a single application of APEG.
This Project Summary was devel-
oped by EPA's Hazardous Waste Engi-
neering Research Laboratory, Cincin-
nati, OH, to announce key findings of
the research project that is fully docu-
mented in a separate report of the same
title (see Project Report ordering infor-
mation at back).
In 1982, numerous sites of 2,3,7,8-
tetrachlorodibenzo-p-dioxin (dioxin,
2,3,7,8-TCDD) contamination were iden-
tified by the U.S. Environmental Protec-
tion Agency (EPA) in Eastern Missouri.
The sites were contaminated in the
early 1970's when waste oil containing
traces of dioxin were applied to horse
arenas and road surfaces to control
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dust. Due to the number of sites and the
volume of soil that must be handled, it
is possible that in situ treatment may
provide the only practical solution to the
dioxin problem.
The Hazardous Waste Engineering
Research Laboratory (HWERL-Ci), in
conjunction with Wright State Univer-
sity, in Dayton, Ohio, previously estab-
lished the ability of alkali polyethylene
glycolates (APEGs) to destroy 2,3,7,8-
TCDD in soil samples under laboratory
conditions. Subsequently, EPA devel-
oped plans to evaluate the applicability
of APEGs to dioxin decontamination in
a controlled field test.
The objective of this study was to
evaluate a selected APEG reagent and
ultraviolet light (UV) under ambient
conditions to determine its capability to
dechlorinate and hence "destroy"
2,3,7,8-TCDD. A statistical sampling de-
sign that would facilitate the compari-
son of results before and after treatment
was to be used. With this approach,
data essential to the development of a
reliable and cost-effective technique for
the destruction detoxification of toxic
halogenated organics such as TCDD
would be obtained.
In conjunction with the Research Tri-
angle Institute (RTI), EPA implemented
the statistical design in a field study
conducted in October through Novem-
ber 1984 at Shenandoah Stables.
The test plan involved the construc-
tion of two sites, one inside the stable
arena and one outside the stable at a
site referred to as the "slough."
A total of 1,060 cubic yards of TCDD
contaminated soil were removed from
the stable, deposited in the slough area
immediately southeast of the stable,
and capped with clay in the 1970s. The
TCDD concentration in this area aver-
aged 1,175 ppb. On the 25 test plots in-
side the arena, the TCDD concentration
averaged 110 ppb.
Extremely wet weather forced the
postponement of the outside UV and
APEG tests until summer 1985.
The basic experimental design for the
Shenandoah Stable site consisted of a
5x5 Latin square involving 25 plots
(identified by row and column). The five
treatments, designated by the letters A
through E as shown below, were ran-
domly assigned within the Latin square
configuration:
• A = APEG treated, covered
• B = Not treated, covered
• C = APEG treated, uncovered
• D = Not treated, uncovered
• E = Methyoxypolyethylene glycol
(MPEG)-treated, uncovered
Two sections of bleachers that were
liberally coated with dust were identi-
fied. Each section contained two seating
planks 31.5-feet long and 9.6-feet wide,
and arranged in tiers. The planks were
coated with dust ranging in depth from
1 16 inch to 1/8 inch. It was assumed
that since all four planks had been ex-
posed to the same environment, each
would contain approximately the same
levels of 2,3,7,8-TCDD. Therefore, one
plank of each set could be treated with
APEG.
APEG and MPEG (polyethylene glycol
monomethyl ether, average molecular
weight 350) were applied to designated
3-foot by 3-foot test plots. A plastic cov-
ering was then placed over the appro-
priate plots. To prepare the APEG
reagent, the MPEG was combined with
potassium hydroxide and also used
alone as a reagent control.
The plots designated A and C (Fig-
ure 1) were given a single treatment of
APEG. The initial treatment consisted of
filling a 2-gallon steel watering can hav-
ing a perforated spray cap with 7-liters
of APEG. The reagent was then dis-
persed over the surface of a plot and
allowed to fill the frame. The surface of
the treated plots was then raked and
stirred to a depth of approximately
3 inches with a 3-pronged garden tool in
order to mix the APEG and the soil.
Those plots designated as E received a
similar treatment using 7 liters of
MPEG. Plots designated as B and D
were left untreated; however, their sur-
Rear of stable (\): Top of site
From of stable (\): Bottom of site
Figure 1. Plot assignments for the arena site.
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faces were raked to simulate the mixing
that had occurred in A, C, and E.
The plots designated by A and B were
covered with 0.5 mm black polyethyl-
ene plastic. A3 1/2-foot, 1-inch by 1-inch
dowel was centered horizontally over
the sampling frame to provide central
elevation for the covering and to pro-
mote the drainage of condensate to the
sides of the plot. The 5-foot by 5-foot
plastic squares were then placed over
the frame.
Additional treatments involved the
application of a 2 to 1 toluene-APEG
mixture to those sites previously
treated with APEG alone. The MPEG
treatments were not modified.
The previously identified bleacher
sections were treated during the third
visit. A standard 3-gallon hand1
pressurized agricultural sprayer was
used to apply the APEG. The sprayer
was filled with a 2 to 1 toluene-APEG
mixture and the spray nozzle was tested
to see that it would emit a uniform
spray.
After adjusting the spray nozzle, the
can was refilled and two 31-foot by 9.6-
foot (302.4 square feet) planks of
bleacher were each sprayed with ap-
proximately 1 1/2 gallons of APEG
reagent.
The concentration of 2,3,7,8-TCDD at
Shenandoah Stables had been previ-
ously determined by EPA to have a
nonuniform distribution. Consequently,
the goal of the sampling protocol was to
characterize each plot over time that
would account for the potential variabil-
ity. By compositing and analyzing a se-
ries of point samples from within each
plot, a representative 2,3,7,8-TCDD con-
centration could be determined. The
sample points were based on a regular
pattern, the starting point of which was
to be randomly selected for each
sample.
The analyses of the soil and bleacher
samples for 2,3,7,8-TCDD were per-
formed under the auspices of the Super-
fund National Dioxin Study. Conse-
quently, four contract laboratories were
assigned by the Sample Management
Office in Alexandria, Virginia, to per-
form the TCDD analyses. All analyses
were performed in accordance with the
established EPA TCDD analysis protocol
requirements for laboratories in the
study.
Duplicate measurements of dioxin
concentration levels within each of the
plots were made at four times: the first
pair of measurements during a baseline
Dioxin
Concentration (ppb)
150-
140-
130-
120-
110-
100-
90-
80-
70-
60
.00
-Cr
- 9 days -
- 13 days -
Measurement Time
- 12 days -
Legend- APEG
MPEG
Untreated
Covered •
Uncovered O
Figure 2. Estimated mean dioxin concentrations versus measurement time.
period (before application of any treat-
ment), and the remaining pairs, after
each of the three treatment applica-
tions. A total of 200 measurements
(2 measurements per plot; 25 plots;
4 time periods) were finally taken. Due
to miscommunications between the
Sample Management Office and the
contract laboratories, all sample results
were not received. Consequently, there
were 31 measurements for which the
dioxin concentrations were not avail-
able for analysis. However, each of
100 cells (25 plots, 4 time periods) had
at least one good dioxin determination.
A multivariate analysis of variance
was performed on the sample data
using the dioxin data from the four sam-
pling visits, looking at them over time as
the dependent variables, and looking at
row, column, and treatment as the inde-
pendent variables.
When only the initial measurement
versus the final measurements are in-
spected (Figure 2), there is an effect for
APEG versus no treatment as well as for
MPEG versus no treatment. When the
effects of the no treatment "treatments"
are compared, both show a statistically
significant increase in dioxin levels. The
effects of the MPEG and APEG treat-
ments show a decrease in dioxin levels
but are not statistically significant.
The results from one application of
APEG to TCDD contaminated bleachers
are summarized in Table 1.
The results from field tests of APEG
are not comparable to the achieved
68 percent reduction of TCDD in soil
after 21 days under ambient conditions
in the laboratory. A recently completed
study has established that both APEG
and MPEG are hygroscopic and can ab-
sorb within 9 days greater than 10 per-
cent of its weight in moisture from the
air. Moisture in excess of four percent
tends to deactivate the APEG reagents
and reduce their ability to destroy TCDD
and other haloorganic compounds.
Soil moisture in test plots at Shenan-
doah Stables reached levels of 18 to 20
Table 1. Percent Reduction of TCDD on
Bleacher Surfaces
Shenandoah Stable bleacher dust
Initial TCDD in
dust (PPB)
76.9
65.5
TCDD after
12 days
of treatment
64.0
44.0
Percent
reduction
16.8
32.8
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percent of the weight of the soil during
the study. Also, the humidity remained
high due to unseasonably heavy rainfall
during the test period of October
through November 1984; the average
air temperature at the test site was 35°F.
This low temperature did not contribute
to drying of soil, nor could it enhance
the APEG rate of TCDD destruction in
the soil or on the bleacher planks.
To overcome the adverse influence of
soil and air moisture on APEG, two new
TCDD destruction processes are being
developed and demonstrated success-
fully on the laboratory scale. They are
heated slurry and heated in situ
processes.
In the slurry process, the TCDD-
contaminated soil is excavated and
placed in an onsite reactor containing
APEG. The soil is processed for 1 hour
at 70° to 100°C to decompose the dioxin
to levels below 1 ppb. The APEG is re-
covered and reused. In the in situ pro-
cess, the soil is treated in-place by
adding the reagent directly to the soil,
as was done at the Shenandoah site,
followed by heating the soil to 70°C with
radio frequency or passive solar tech-
niques. Both the heated slurry and
heated in situ processes are scheduled
to be tested in the field during fiscal
years 1985-1986.
The EPA authors, Charles J. Rogers (also the EPA Project Officer, see below),
Albert J. Klee, and Alfred Kornel, are with Hazardous Waste Engineering
Research Laboratory, Cincinnati, OH 45268: and James B White, Keith B.
Leese, and Andy C. Clayton are with Research Triangle Institute, Research
Triangle Park, NC 27709
The complete report, entitled "Interim Report on the Feasibility of Using UV
Photolysis and APEG Reagent for Treatment of Dioxin Contaminated Soils,"
(Order No. PB 85-232 619/AS; Cost: $11.50, subject to change) will be
available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Hazardous Waste Engineering Research Laboratory
U.S. Environmental Protection Agency
Cincinnati, OH 45268
United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
Official Business
Penalty for Private Use $300
EPAy600/S2-85/083
0000329 PS
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