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.  By 1945 an estimated 1.2 million tons of soil surrounding production plants had been contaminated. (Lewes et.al, 2004)  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)

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)  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)

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

RDX - Two Electron Reductive Pathway

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

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

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

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

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

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

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

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.  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.

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

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

Enhancing Anaerobic Nitramine Treatment

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

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

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.  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.

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.  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.

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  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

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.  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.

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

Conclusion

QUESTIONS?