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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