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LOW-TEMPERATURE, LIQUID-PHASE PROCESSES 131 BIODEGRADATION OF REACTION PRODUCTS FROM THE CHEMICAL PROCESSING OF GB AND VX An alternative to the direct biological or biochemical treatment of GB or VX would be to couple initial chemical processing of the agent with biological degradation of the reaction product, especially for the complete destruction of the products of well-defined chemical reactions (see the earlier sections in this chapter on chemical processes). Biological systems offer much promise to manage bulk materials of lower toxicity. The potential hazards of the longer reaction times and storage of these systems, and associated fermentation safety concerns would all be greatly reduced because of the lower toxicity of the chemical process streams. For this application, there are several major issues that require consideration: ⢠What are the reaction products of chemical processing of the primary agent and of the contaminants present with the agent? ⢠Are there efficient biological systems that have been adequately characterized for each specific purpose? ⢠What is the impact of carrier materials in the streams? For example, how much dilution of the products from chemical processing of GB and VX is necessary to provide concentrations of organic compounds appropriate for biological processing? ⢠What are the management considerations for the volume and characteristics of the resulting biomass and neutralization salts? Each chemical process discussed earlier in this chapter results in reaction products that could be further treated by biodegradation (see earlier section on chemical detoxification processes). As an example, the biodegradation of the reaction products of H will be discussed in the next section. When organic solvents are used for the chemical degradation of GB and VX, subsequent biodegradation must contend with the reaction solvent, reaction products, and impurities or their products. For example, reaction with potassium hydroxide in methanol would require degradation of the methanol carrier solvent as well as the reaction products; the aqueous reaction of GB and VX with ethanolamine would require degradation of ethanolamine as well as the reaction products. Biodegradation of the solvents is readily achievable; however, biodegradation of many of the reaction products has not been directly investigated. The most likely biodegradation pathways include the following: ⢠cleavage of the phosphonate ester linkage followed by oxidation of the resulting alcohol;
