Previous work in our laboratory over the past four years has shown that the high explosives hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) and octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) can be readily destroyed by alkaline hydrolysis. The hydrolysis process produces large quantities of concentrated but conventional wastewaters, containing acetate, formaldehyde, formate, ammonia and nitrite. To treat these wastewaters, a denitrifying (anoxic) biological process was developed that converts the hydrolysates to harmless endproducts, such as N2 and CO2. The nitrite is produced during the hydrolysis process as the electron acceptor, but additional nitrite is required to completely oxidize the carbon compounds. Over 90 percent of each organic carbon source can be removed in a packed-bed, upflow reactor in 3 hours hydraulic retention time. Formaldehyde and acetate are first degraded at approximately the same rate, and formate is degraded more slowly. Results closely match the stoichiometry predicted by the empirical redox equations describing the process.

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