Bioremediation%20of%20Explosive%20Contaminants

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Bioremediation of Explosive Contaminants

• Matt Mahler

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Introduction

• In the late 19th century many nitramine compounds
  were created through the process of nitration.
• During WW I and WW II their application for
  industrial and military purposes was
  investigated.
• By 1945 an estimated 1.2 million tons of soil
  surrounding production plants had been
  contaminated.
• (Lewes et.al, 2004)

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Introduction Contd

• Enter the environment through wastewater from
  production plants.
• Many bioremediation techniques are currently
  being investigated.
• Compounds Discussed TNT, RDX, HMX and CL-20
• (Lewes et.al, 2004)

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Bioremediation of RDX

• Readily degradable in a
• variety of environments.
• Aerobic and Anaerobic Mechanisms
• Two-Electron Reductive Pathway and Denitration
• (Crocker et. al, 2006)

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RDX - Two Electron Reductive Pathway
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RDX - Two Electron Reductive Pathway Contd

• Special Notes
• Mechanism II No Ring Cleavage
• Mechanism III Uses Oxireductase
• Still Disagreement Among Researchers

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RDX - Denitration

• Believed to be the most common method of RDX
  Degradation.
• Occurs aerobically and anaerobically

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RDX - Denitration Contd
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RDX - Denitration Contd

• Special Notes
• Aerobic
• NDAB is Readily Degraded by Many Organisms
• In the anaerobic denitration process two
  electrons are added prior to ring cleavage.

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Bioremediation of HMX

• Most methods that degrade RDX have
• also been shown to degrade HMX.
• Also involves aerobic and anaerobic
• processes.

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Bioremediation of HMX

• Aerobic
• Methylobacterium Cometabolize HMX with Carbon
  Dioxide

• Anaerobic
• Some process as RDX , however McCormicks Pathway
  not aplicable.

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Bioremediation of CL-20

• Recently Developed Nitramine
• 20 More Powerful Than HMX
• Degradation Mechanisms Similar To Those of RDX
  and HMX.

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Bioremediation of CL-20

• Anaerobic Degradation
• Cloistridium Utilizes CL-20 for Cell Growth
• Catalyzed by Dehydrogenase
• End Products Acetic Acid, Glyoxal, Nitrous Oxide
  and Nitrogen Dioxide

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Bioremediation of CL-20

• Aerobic Degradation
• While possible, CL-20 most occur in high
  concentrations for process to take place.
• In environments that support fungal growth,
  white-rot fungi is responsible for aerbic
  mineralization of CL-20.

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Enhancing Anaerobic Nitramine Treatment

• Anaerobic Treatment of HMX, RDX and TNT
• Current Limiting Step in Process is the
  Availability of Substrate.
• Historically Starch Has Been Used

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Enhancing Anaerobic Nitramine Treatment

• Anaerobic Treatment of HMX, RDX and TNT
• Recent Research Introduced Propylene Glycol and
  Ethanol to Cultures
• Consumption of these Molecules Produces Hydrogen
  Gas

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Enhancing Anaerobic Nitramine Treatment
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Enhancing Anaerobic Nitramine Treatment

• Conclusion
• Addition of Propylene Glycol and Ethanol Did
  Increase Rate of Degradation
• Not Necessary for TNT and RDX Degradation.

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Enhancing Nitramine Treatment

• Enhancing Treatment CL-20
• Added Sucrose, Pyruvate, Yeast, Acetate, Glucose
  and Starch to act as Carbon Sources

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Enhancing Ntramine Treatment

• Conclusions
• The addition of these substrates does increase
  the rate of CL-20 Degradation.
• Process is independent of microbial cell growth.
• Over half randomly selected microbes could
  degrade CL-20.

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Aerobic Degradation of CL-20

• Researchers investigated the use of P.
  Chrysosporium for its use as a CL-20 degrading
  molecule.
• At the end of the 8 day experiment concentrations
  of CL-20 were virtually non-existant.
• Growth of fungi was observed.

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Case Study

• Louisiana Army Ammunition Plant
• Currently disposes of waste through dumping and
  incineration.
• Experiment performed to analyze the potential use
  of land farming and soil slurry as potential
  methods of waste treatment

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Case Study

• Results
• Soil Slurry showed 99 removal of TNT and near
  complete removal of HMX and RDX at the end of the
  182 day experiment
• Land Farming showed 82 removal of TNT and little
  to know RDX and HMX removal after same amount of
  time.

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Conclusion

• The production of nitramines is only expected to
  increase.
• More efficient and economical degradation
  mechanisms must be found.

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Conclusion
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QUESTIONS?