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Combined Perchlorate and RDX Treatment in Biological Fluid Bed Reactors

Combined Perchlorate and RDX Treatment in Biological Fluid Bed Reactors. PRESENTATION AT THE NDIA 30 TH ENVIRONMENTAL AND ENERGY SYMPOSIUM APRIL 7, 2004 Presented by William J. Guarini. Acknowledgements Aerojet U.S. Army U.S. Army Corps of Engineers U.S. Navy US Filter SERDP ESTCP

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Combined Perchlorate and RDX Treatment in Biological Fluid Bed Reactors

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  1. Combined Perchlorate and RDX Treatment in Biological Fluid Bed Reactors PRESENTATION AT THE NDIA 30TH ENVIRONMENTAL AND ENERGY SYMPOSIUM APRIL 7, 2004 Presented by William J. Guarini

  2. Acknowledgements Aerojet U.S. Army U.S. Army Corps of Engineers U.S. Navy US Filter SERDP ESTCP AMEC

  3. Presentation Overview • Biodegradation of Perchlorate/RDX/MNX • Fluidized Bed Reactor • Case Histories – Full Scale FBR • Aerojet • Longhorn • MMR Demo – Perchlorate/RDX/MNX • Summary

  4. Perchlorate Biodegradation Biomass + CO2 Substrate ClO2- ClO3- Cl- + H2O ClO4- * Highly Favorable Reaction (-801 kJ/mol acetate) * Several Different Genera Isolated (Wolinella, Ideonella, Dechlorospirillum, Dechlorisoma)

  5. Chemical Structures Octahydro-1,3,5,7-tetranitro- 1,3,5,7-tetrazocine (HMX) 2,4,6-Trinitrotoluene (TNT) Hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX)

  6. Generalized Biodegradadtion In most cases, transformation and/or biodegradation appears to be a gratuitous activity, often times “cometabolic” in nature. Ability to transform explosives seems to be widespread, and has been observed in: • bacteria (both Gram+ and Gram- genera) • fungi (mostly white rot species) • Plants Most commonly observed mechanism is sequential reduction of the NO2- groups, followed by eventual ring cleavage.

  7. Generalized Biodegradation Pathways RDX DNX TNX Formaldehyde Methanol Hydrazine Hexahydro-1-nitroso- 3,5-dinitro- 1,3,5-triazine (MNX) CO2 N2O Bis(hydroxymethyl) nitramine Methylenedinitramine

  8. Utilization of Electron Acceptors

  9. Fluidized Bed Reactor Flow Schematic FLUIDIZED BED REACTOR EFFLUENT Biomass Control RECYCLE FEED CONTAMINATED GROUNDWATER NUTRIENT(S) ELECTRON DONOR Distribution Headers INFLUENT

  10. Fluidization of Media FBR FBR Microbes 40-60% 25-30% Set Specific Density of Sand Particles As the Biomass Grows, the Specific Density Decreases as Combined Volume of the GAC and Biomass Increases Post Start-up Start-up

  11. FBR Advantages • High biomass concentration means long SRT and short HRT • High volumetric efficiency translates to compact system; • Simplicity of operation minimizes need for operator attention

  12. Key Mechanical Components • Device and method used to distribute influent flow to the reactor • Device and method used to control the expansion of the fluidized bed due to biofilm growth • Method to control electron donor dosage rate

  13. Full-Scale Perchlorate Treatment System Aerojet Facility - Rancho Cordova California • FBR SYSTEM • 2 - 8 mg/L perchlorate • 6,000 GPM flow rate • Four 14-ft diameter units • Ethanol as electron donor • GAC media Atlas V

  14. Aerojet

  15. Aerojet FBR Performance Start-up data shown: <4 g/L for > 5 years

  16. Full-Scale FBR System #2 Longhorn Army Ammunition Plant – Karnack, Texas FBR System 15 mg/L perchlorate design 50 gallons per minute flow rate One 5-ft diameter unit Acetic acid as electron donor GAC media

  17. Longhorn

  18. LHAAP FBR Performance Influent Effluent Currently operating 3+ years. Effluent consistently <4 µg/L.

  19. Other FBR Sites • McGregor NWIRP • Kerr-McGee Chemical, LLC • Jet Propulsion Lab

  20. MMR FBR Site Evaluation Can FBR systems remediate low concentrations of perchlorate? Less than 100 g/L (ppb) Can FBR systems concurrently degrade explosives as well as perchlorate? Both biological processes are anoxic reductive processes requiring electron donors Can a single FBR replace traditional lead-lag arrangement of FBR and GAC? What treatment levels are attainable?

  21. MMR Groundwater Contaminant Concentrations Perchlorate 100 g/L RDX 190 g/L HMX 20 g/L Nitrate 8 mg/L

  22. FBR Treatability Study - Set-up Granular activated carbon (GAC) FBR #1 fed acetate (simple organic substrate) FBR #2 fed molasses (complex organic substrate) FBR #3 was a control (no substrate or nutrients) Each column fed groundwater until perchlorate effluent concentrations approached influent concentrations meaning GAC saturated with perchlorate Each column wrapped with cooling coil to maintain temperature at ~17C

  23. FBR Treatabililty Results - Perchlorate

  24. FBR Treatability Results - RDX

  25. RDX Mass Balance

  26. RDX Intermediates and Other Explosives

  27. FBR Treatability Study Conclusions Success with FBR utilizing acetate and electron donor substrate (FBR #1) At HRT of 80 minutes Perchlorate reduced from 100 g/L to < 1.5 g/L RDX reduced from 190 g/L to < 2 g/L HRT of 35 minutes Perchlorate reduced from 100 g/L to < 1.5 g/L RDX could be removed by secondary GAC unit

  28. FBR Treatability Study Conclusions The molasses fed FBR (FBR #2) degraded perchlorate and RDX, but to a lesser extent RDX that sorbed to the GAC in FBR #1 (acetate) was consistently 2 orders of magnitude lower than in FBR #2 and FBR #3 (control). This tells us that the biologically active film on the GAC in FBR #1 was effective at destroying a significant amount of sorbed RDX FBR can perform as a stand alone alternative to traditional lead-lag multiple step treatment trains for perchlorate and explosives

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