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Bioremediation of Explosive Contaminants

Bioremediation of Explosive Contaminants. Matt Mahler. 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.

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Bioremediation of Explosive Contaminants

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  1. Bioremediation of Explosive Contaminants Matt Mahler

  2. 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)

  3. Introduction Cont’d • 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)

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

  5. RDX - Two Electron Reductive Pathway

  6. RDX - Two Electron Reductive Pathway Cont’d • Special Notes • Mechanism II: No Ring Cleavage • Mechanism III: Uses Oxireductase • Still Disagreement Among Researchers

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

  8. RDX - Denitration Cont’d

  9. RDX - Denitration Cont’d • Special Notes • Aerobic: • NDAB is Readily Degraded by Many Organisms • In the anaerobic denitration process two electrons are added prior to ring cleavage.

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

  11. Bioremediation of HMX • Aerobic • Methylobacterium Cometabolize HMX with Carbon Dioxide • Anaerobic • Some process as RDX , however McCormick’s Pathway not aplicable.

  12. Bioremediation of CL-20 • Recently Developed Nitramine • 20% More Powerful Than HMX • Degradation Mechanisms Similar To Those of RDX and HMX.

  13. 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

  14. 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.

  15. 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

  16. 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

  17. Enhancing Anaerobic Nitramine Treatment

  18. Enhancing Anaerobic Nitramine Treatment • Conclusion • Addition of Propylene Glycol and Ethanol Did Increase Rate of Degradation • Not Necessary for TNT and RDX Degradation.

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

  20. 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.

  21. 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.

  22. 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

  23. 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.

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

  25. Conclusion

  26. QUESTIONS?

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