vvEPA
United States
Environmental Protection
Agency
EPA/540/MR-95/529
August 1995
SUPERFUND INNOVATIVE
TECHNOLOGY EVALUATION
Demonstration Bulletin
Ex-Situ Anaerobic Bioremediation Technology - TNT
J. R. Simplot Company
Technology Description: The J. R. Simplot Ex-Situ Anaerobic
Bioremediation System, also known as the J.R. Simplot Anaero-
bic Biological Remediaton Process (the SABRE Process), is a
technology designed to destroy nitroaromatic and energetic com-
pounds. The process does not evolve any known toxic intermedi-
ates at the completion of treatment. The nitroaromatic analyte of
interest during this demonstration was 2,4,6-trinitrotoluene (TNT),
an explosive compound used in ordnance operations. [NOTE: A
separate Demonstration of this technology was previously under-
taken with dinoseb (2-sec-butyl-4,6-dinitrophenol) as the con-
taminant of interest. The results of this Demonstration are reported
independently.] The theory of operation behind the J. R. Simplot
bioremediation process is that TNT-contaminated soils (or liq-
uids) can be treated using an anaerobic consortium of soil micro-
organisms. Under aerobic conditions, degradation of TNT forms
polymerization products that are potentially toxic. Anaerobic deg-
radation of TNT takes place without the presence of these toxic
polymerization products at the completion of treatment. The J.R.
Simplot technology mixes a carbon source with contaminated soil
and then adds water and phosphate buffers to create a slurry
adjusted to the required pH. This prompts aerobic microorgan-
isms to consume the carbon source and thus the oxygen. This
lowers the redox potential (Eh) of the slurry and creates anaerobic
conditions. Anaerobic microorganisms are then stimulated to con-
sume toxins present in the slurry. The J.R. Simplot Company
proposes to mix the carbon source with the slurry water prior to
contaminated soil addition in the future.
Figure 1 presents a schematic flow diagram of the J. R. Simplot
Ex-Situ Anaerobic Bioremediation System that was used during
the Demonstration Test. Initially, excavated soil was sent through
a vibrating screen to remove large rocks and other debris. The
oversize rocks and debris can be treated by a separate technol-
ogy onsite or transported offsite and disposed of at a licensed
waste disposal facility. V/hen the oversize rocks and debris com-
prise a large fraction of the contaminated soil, they may be
passed through a rock/soil washing system with the water being
added to the bioreactor or, alternately, crushed to an appropriate
diameter and then added to the bioreactor for treatment. Enoygh
water was added to the bioreactor to provide one liter of water for
each kilogram of soil to be treated. Phosphate buffers were
added to the system to control the pH. Batches of soil and a J.R.
Simplot potato-processing starch byproduct (2% by weight) were
mixed together by hand and added to the bioreactor until loading
was completed. After fill>ng the bioreactor, 0.02 m3 (a 5-gal pail)
of soil previously treated by the J.R. Simplot process was added
Contaminated soil
h .-, v~ ,% ....ft..,".
1
i
Vibrating Screen
| * ;w-" --
Contaminated soil
> 15.9mm
Figure 1. J.R. simplot process flow diagram for the TNT SITE demonstration test.
Printed on Recycled Paper
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to the bioreactor. This previously treated soil contained the natu-
rally selected microorganisms necessary for the degradation of
TNT using the anaerobic process. The entire contents of the
bioreactor were mixed together (lanced) on a biweekly basis.
Based on laboratory studies, the preferred operating conditions
for the degradation of the nitroaromatics are between 35 and
37°C and a pH below 8 (ideally between 6.0 and 7.0 for TNT
degradation and between 7.5 and 8.0 for dinoseb degradation).
Waste Applicability: This technology is suitable for soils and
liquids contaminated with nitroaromatic and energetic compounds.
However, the media to be treated must not contain total hydrocar-
bons >1,000 mg/kg as measured by EPA Method 418.1 (TRPH).
This technology is a sulfate reducing process, therefore, toxic
metals will be reduced to their sulfide form, making the metals
less toxic to the microorganisms.
Demonstration Results: Two evaluations of the J. R. Simplot
Ex-Situ Anaerobic Bioremediation System have been performed
tinder the Superfund innovative Technology Evaluation (SITE)
Program. The first Demonstration occurred in June/July 1993 at
Bowers Field, a municipal airport in the Ellensburg, WA.-This-site-
was contaminated with dinoseb, an agricultural herbicide. The
source of the contamination at this site is suspected to be from
crop dusting activities in Central Washington during the agricul-
tural season. The results of this successful Demonstration are
reported in a separate Demonstration Bulletin. The second Dem-
onstration Test is the subject of this Bulletin. This Demonstration
was initiated at the Weldon Spring Ordnance Works (WSOW) site
in September 1993 and concluded in late June 1994. The WSOW
was a U. S. Army World War II Ordnance Works for the manufac-
ture of TNT that ceased production in 1945. The present day soil
contamination is the result of previous Ordnance Works opera-
tions.
During the second Demonstration, approximately 23 m3 (30 yd3)
of soil contaminated with TNT at an average concentration of
1,500 mg/kg (on a dry basis) based on 41 samples using an
HPLC procedure was placed in the portable bioreactor onsite. If a
larger volume of soil had been used for the Demonstration, then
one or more in-ground, lined pits would have been more appropri-
ate for use as bioreactors than the small, portable bioreactor. The
Demonstration was anticipated to last approximately six weeks,
however, daily sampling (using a field test kit) showed that TNT
was still present at low levels in the slurry up to approximately 9
mon later when post-treatment sampling was initiated. The ex-
tended length of treatment time may be due, in part, to the cold
temperatures encountered over the harsh winter of 1993 that
prompted the installation of heaters to maintain a suitable bioreactor
temperature.
United States
Environmental Protection Agency
National Risk Management Research Laboratory (G-72)
Cincinnati, OH 45268
Official Business
Penally for Private Use
$300
EPA/540/MR-95/529
Demonstration testing of the J. R. Simplot Ex-Situ Anaerobic
Bioremediation Technology for TNT gave the following results:
Theprocesscan reduce the levels of TNT in thefeed soil. Based
on an average pre-treatment slurry concentration of 1,500 mg/
kg (on a dry basis) and a final post-treatment slurry concentra-
tion of 8.7 mg/kg (on a dry basis) of 40 samples analyzed by an
HPLC procedure, a 99.4% reduction of TNT was achieved. The
95% Confidence Interval for this Removal Efficiency is 98.3% to
99.9%.
A 95% Removal Efficiency, the critical objective of this Demon-
stration, was achieved in approximately 5 mo of remediation.
Intermediate byproducts from the biological degradation of TNT
were found to increase during the course of treatment and then
decrease to below the analytical detection limit at the comple-
tion of the Demonstration.
Relative toxicity studies (early seedling growth, root elongation,
and earthworm reproduction) from the commencement of the
treatment process to the 95% Reduction Efficiency point showed
that the technology successfully reduced the toxicity of the
contaminated soil.
«^The soil-type remediated-was clayey-gravel with-sand.-This
provided good adhesion properties for the TNT and made
degradation more difficult.
The ITER describing the complete demonstration and other perti-
nent information will be available in the Fall of 1995.
For Further Information:
EPA Project Manager
Wendy Davis-Hoover
U. S. EPA National Risk Management Research Laboratory
5995 Center Hill Avenue
Cincinnati, OH 45224-1701
(513) 569-7206
Technology Developer Contact:
Russ Kaake
J. R. Simplot Company
P.O. Box 912
Pocatello, ID 83201
(208) 234-5367
Tom Yergouich
J.R. Simplot Company
P.O. Box 912
Pocatello, ID 83201
(208) 238-2850 (800) 635-9444
BULK RATE
POSTAGE & FEES PAID
EPA
PERMIT No. G-35
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