Biodegradation of HD and Tetrytol Hydrolysates in a Pilot Scale Immobilized Cell Bioreactor

To address public concerns over the safe destruction of the U.S. chemical weapon stockpile, the Assembled Chemical Weapons Assessment (ACWA) Program identified neutralization followed by biodegradation as having potential for destroying the chemical agent and burster charge fills of chemical agent projectiles. This report describes the pilot scale study conducted by the authors at the U.S. Army Edgewood Chemical Biological Center (ECBC), APG, MD. This research builds upon the neutralizationBIODEGRADATION PROCESS DEVELOPED AT ECBC and expands that process to include the burster fills found in mustard (HD) agent projectiles. A 1000-gal immobilized cell bioreactor (ICB) system was used to demonstrate the ability of an activated sludge consortium to degrade the chemical constituents of the US Army's 105-mm chemical agent projectile. The study demonstrated the ability of the Water Hydrolysis of Energetic and Agent Technologies (WHEAT) and the ICB to degrade 99.999% of hydrolyzed HD and its schedule-two breakdown products. During the test period, the ICB system processed 16,896 lb of HD hydrolysate and 660 lb of tetrytol hydrolysate. During the system validation, HD hydrolysate and its breakdown products were degraded to below detectable limits in all system effluents. Through a three-step process, 50% of the effluent was recycled into the ICB. Liquid effluents were characterized as non-toxic by the Toxicity Characteristic Leaching Procedure (TCLP). The ICB, process, and study findings are presented. Prepared in collaboration with Honeywell International, Des Plaines, IL and GEO-Centers, Inc., Gunpowder, MD.