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APPLICATION OF ALTERNATIVE TECHNOLOGIES TO THE DESTRUCTION OF THE U.S. CHEMICAL WEAPONS 190 STOCKPILE to subsequent processing steps that accomplish irreversible conversion by oxidation. Low-Temperature, Low-Pressure, Liquid-Phase Oxidation Although demilitarization goals can be met by detoxification, oxidation of all carbon to carbon dioxide (CO2) is highly desirable for final disposal. There has been little investigation of the use of low-temperature oxidation processes for waste streams resulting from low-and medium-temperature detoxification processes. However, treatment of contaminated groundwater by low-temperature oxidation is an active field of investigation that provides some leads on treating wastes from agent detoxification. At temperatures below the boiling point of water, very active oxidizing agents (with catalysis) are required for oxidation. Peroxydisulfate salts are capable of oxidizing most organic compounds to CO2 but would produce a very large solids waste stream. It has been proposed that to optimize the process, spent reagent be recycled to electrolytic regeneration and catalyzed H2O2 be used to convert the more reactive components (Cooper, 1992). Ultraviolet light can activate mixtures of ozone (O2) and H2O2 and is an option in treating contaminated groundwater. However, the large electricity requirements of this process for treating large reaction product streams are disadvantageous compared with other options. Biological oxidation is commonly applied for industrial and municipal waste streams. Although applications to the waste stream from demilitarization have not been developed, research on such processes might well prove successful. Moderate-Temperature, High-Pressure Oxidation Both wet air oxidation (WAO) and supercritical water oxidation (SCWO) processes can detoxify and convert residual organic materials to CO2. WAO is carried out at lower temperatures then SCWO, and requires residence times greater than 1 hour. Even then, more refractory organic compounds remain. However, these residuals are judged by the committee to be suitable for biological degradation. SCWO, at higher temperatures and pressures, can achieve a greater conversion of all organics in about 10 minutes. Because pure oxygen is used in this process, waste gas is primarily CO2, which can, if necessary, be removed as solid calcium carbonate (CaCO3) or limestone). Adaptation of WAO to use pure oxygen would require a pilot plant program.
