United States
Environmental Protection
Agency
EPA/540/MR-94/508
April 1994
SUPERFUND INNOVATIVE
TECHNOLOGY EVALUATION
Demonstration
Bulletin
Ex-Situ Anaerobic Bioremediation System: Dinoseb
J.R. Simplot Company
TECHNOLOGY DESCRIPTION: The J.R. Simplot Ex-situ
Anaerobic Bioremediation System is a technology designed to
destroy nitroaromatic compounds without forming any toxic inter-
mediates. The nitroaromatic compound of interest during this
demonstration was dinoseb (2-sec-butyl-4,6-dinitrophenol) an ag-
ricultural herbicide used to defoliate potatoes and other legumes.
(NOTE: A separate demonstration of this technology is being
undertaken with 2,4,6-trinitrotoluene (TNT) as the contaminant of
. interest. The results of this demonstration will be reported inde-
pendently.) The theory of operation behind the J.R. Simplot
bioremediation process is that dinoseb-contaminated soils (or
liquids) can be treated using an anaerobic consortium of soil
microorganisms. Under aerobic conditions, degradation of dinoseb
forms polymerization products that are potentially toxic. Anaero-
bic degradation of dinoseb takes place without the formation of
these polymerization products. The J.R. Simplot technology mixes
a carbon source with contaminated soil and then adds water and
a phosphate buffer to create a slurry. This prompts aerobic
microorganisms to consume the carbon source and oxygen, thus
lowering the redox potential (Eh) of the slurry and creating anaero-
bic oanditions. Anaerobic microorganisms are then stimulated to
consume toxins present in the slurry.
Figure 1 presents a schematic flow diagram of the J.R. Simplot
bioremediation system. Initially, excavated soil is sent through a
vibrating screen to remove large rocks and other debris. The
rocks and debris are washed to remove surface contamination.
This jrinse waiter is combined with make-up water and added to
the bioreactor. Sufficient water is added until the bioreactor con-
tains an amount of water sufficient to provide 1 liter of water for
each kg of soil to be treated. A phosphate buffer is added to the
system to control the pH. Batches of soil and potato starch (2%
by wbight) are homogenized together and added to the bioreactor
until ihe system is 75% full. Optimum conditions for the degrada-
tion [of dinoseb are a temperature of 30 to 35°C and a pH
between 7 and 7.5.
WASTE APPLICABILITY: This technology is suitable for soils
and liquids contaminated with nitroaromatic compounds. How-
ever,! the medium to be treated must be free of toxic metals or
Contaminated Soil
Vibrating Screen
Potato
Waste
Addition
contaminated
soil
> 12.7mm
contaminated
soil
I f < 12.7mm
Homogenization
(using a pug mill)
Mixer
Water From
Screen Overs
Washing
* Clean rejects if contaminants in the soil are water soluble.
Figure 1. Schematic flow diagram of the J.R. Simplot Ex-Situ Anaerobic Bioremeciation Process - Dinoseb.
pH, Redox
Potential, &
Temperature
Probe
Printed on Recycled Paper
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I
any other compounds that may be detrimental to the appropriate
microorganisms.
DEMONSTRATION RESULTS: Two demonstrations of the
J.R. Slmptot Ex-Shu Anaerobic Btoremediation System has been
performed under the Superfund Innovative Technology Evaluation
(SITE) Program. The first demonstration occurred in June/July
1993 at Bowers Field, a municipal airport in the Ellensburg,
Washington area. The source of the contamination can be traced
to crop dusters in Central Washington during the agricultural
season.
During the demonstration 30 m3 (40 yd3} of soil contaminated with
dinoseb at an average level of 28 mg/kg was placed in the
bioroactor. If a larger volume of soil or a molecular bioreactor was
to be used for the Demonstration Test, then a lined pit would have
boon more appropriate than a molecular bioreactor. The demon-
stration was anticipated to last approximately 6 weeks, however,
sampling at the anticipated mid-point of the test (23 days) showed
that dJnoseb was not detected in any of the samples. This was in
sptta of the fact that the average ambient temperature during this
period maintained the bioreactor at an unseasonable 18°C. Thus,
post-treatment sampling was initiated.
Demonstration Testing of the J.R. Simplot Ex-Srtu Anaerobic
Btoremediation System gave the following results:
• The process can reduce the levels of dinoseb in the feed soil to
below detection limits. Based on an average pre-treatment
concentration of 28 mg/kg and af inal post- treatment concentra-
tion beiow the detection limit of the analytical instrumentation a,
>99.8% reduction of dinoseb was achieved.
• No known polymerization products were found in the analysis of
the post-treatment samples.
• Other pesticides (nitroanaline, malathion, and parathion) were
reduced from parts per million levels in the feed soil to belowthe
analytical detection limit in the treated slurry.
• Theprocesscansuccessfullyoperatewithbioreactortempera-
tures as low as 18°C, much below optimum.
• Treatabil'rty studies and, to a limited extent, the Demonstration
Test has shown that continuous mixing of the bioreactor is not
required. A static system can achieve acceptable results pro-
viding the soil, water, and potato starch are well-mixed during
loading of the bioreactor.
The presence of other herbicides and pesticides in the feed soil
negated the meaningful purpose of performing toxicity tests on
the pre- and post-treatment samples as part of the dinoseb
Demonstration Test. However, toxicity tests will be performed as
part of the demonstration for TNT degradation.
An Innovative Technology Evaluation Report describing the com-
plete Demonstration and other pertinent information will be avail-
able in the Summer of 1994.
FOR FURTHER INFORMATION:
EPA Project Manager:
Dr. Wendy Davis-Hoover
U.S. EPA Risk Reduction EEngineering Laboratory
5995 Center Hill Avenue
Cincinnati, OH 45224
(513) 569-7206
•U.S. Government Printing Office: 1994— 550-067/80238
United States
Environmental Protection Agency
Center for Environmental Research Information
Cincinnati, OH 45268
Official Business
Penatty for Private Use
$300
BULK RATE
POSTAGE & FEES PAID
EPA
PERMIT No. G-35
EPA/S40/MR-94/508
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