The biotransformation of hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) in liquid and solid matrices using a prospective consortium
AdvisorOgden, Kimberly L.
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PublisherThe University of Arizona.
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AbstractThe biotransformation of hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) has been researched in three situations: batch liquid phase, micro soil slurry reactors, and in-situ studies. A prospective consortium of bacteria found in horse manure was used as the primary source of microorganisms. From this consortium, five major strains were isolated. Serratia marcescens, one of the isolates, was found to be the most effective microorganism at biotransforming RDX in liquid phase. The growth and the biotransformation mechanism of RDX were characterized for both the consortium and Serratia marcescens. The biotransformation of RDX from soil matrices was tested in well-mixed micro soil slurry reactors and in undisturbed in-situ reactors. In the micro soil slurry reactors, carbon sources were varied (nutrient broth and corn steep liquor) and different bacteria were inoculated into the systems which already contained bacteria indigenous to the contaminated soil. There were two distinguishable pathways for the biotransformation of RDX in the soil slurry reactors. Different carbon sources promoted the biotransformation through the pathways differently. The addition of inocula to the systems did not provide any benefit as to the biotransformation rates. In the in-situ studies, a lag period of about 50 days was observed before biotransformation of RDX began. This lag period was believed to be due to mass transfer limitation and adaptation time for the bacteria. Again, adding other inocula to the indigenous bacteria did not provide any benefit towards the rate of biotransformation of RDX. In this study, bacteria indigenous to non-contaminated soil was tested as well and found not to biotransform RDX.
Degree ProgramGraduate College
Chemical and Environmental Engineering