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APPLICATION OF ALTERNATIVE TECHNOLOGIES TO THE DESTRUCTION OF THE U.S. CHEMICAL WEAPONS 197 STOCKPILE ⢠minimize risks of agent release to nearby communities, risks both associated with continued storage of agent and with the demilitarization operation itself; ⢠ensure the reduction of toxic materials from air in gaseous wastes to acceptable levels; and ⢠minimize final disposal problems for solid and liquid wastes by oxidizing all organic material in solid wastes and minimizing water discharge. The current program schedule has some flexibility, with completion of demilitarization set as late as December 31, 2004, under the international treaty on disarmament. Even so, this outside date will be difficult to meet at sites where construction and operations are delayed. (Treaty requirements for demilitarization are briefly reviewed in Chapter 1.) The risk of catastrophic agent release from continued storage provides an additional incentive for prompt and acceptable choices of technology. Strategies for Disposal At U.S. chemical stockpile disposal facilities, chemical munitions and bulk agents must be removed from storage and transported to the treatment site, where they will be unpacked and disassembled before disposal. Two major demilitarization strategies can be identified: Strategy 1. On-site disassembly and agent detoxification to meet demilitarization requirements and permit transportation to another site or continued local storage of residues. Strategy 1 allows treaty demilitarization requirements to be met with liquid-phase processes that do not produce a significant quantity of gas emissions. Final oxidation of all organic residues, energetics destruction, and decontamination of metals can be deferred by continued local storage or conducted at another site to which materials can be transported for final treatment. This strategy is illustrated in Figure 8-1. Drained agent is destroyed by conversion to less toxic compounds, as through chemical hydrolysis, or completely oxidized and converted to CO2, water, and salts, as through low- pressure, liquid-phase oxidation or high-pressure, wet air or supercritical water oxidation. Energetics and contaminated metal parts and containers would be treated with decontamination fluid to reduce toxicity to level 3X before transportation to another site. Strategy 1 has the advantages of nearly eliminating local discharge of flue gas, meeting the requirements for demilitarization, and eliminating the
APPLICATION OF ALTERNATIVE TECHNOLOGIES TO THE DESTRUCTION OF THE U.S. CHEMICAL WEAPONS 198 STOCKPILE FIGURE 8-1 Unit processes in demilitarization Strategy 1: disassembly and agent detoxification, with storage or transportation of residue. risk of agent release from continued storage. It has the disadvantage of requiring additional time (5 to 12 years) for the research, development, and demonstration of new technologies. It would also delay final disposal of energetics and contaminated metal. It is assumed here that the small amounts of waste gas could be treated along with ventilation air by the activated-carbon adsorption beds that are part of the baseline design. Strategy 2. Conversion of agent and disassembled weapons to salts, CO2 water, and decontaminated metal (mineralization). In Strategy 2, mineralization is completed without long-term storage of agent, energetics, or metal parts and containers. This strategy meets all stated goals by oxidation and heat treatment to produce the waste streams noted. Strategy 2 is illustrated in Figure 8-2.
APPLICATION OF ALTERNATIVE TECHNOLOGIES TO THE DESTRUCTION OF THE U.S. CHEMICAL WEAPONS 199 STOCKPILE FIGURE 8-2 Unit processes for demilitarization Strategy 2: mineralization. For agent, detoxification (as in Strategy 1) can precede the final mineralization processes, or agent can be directly mineralized, as in the baseline technology. The two-step procedure of detoxification by hydrolysis followed by incineration to complete oxidation has been used in the United States and worldwide. It is apparently of some continuing interest for the Russian stockpile disposal program. In this approach, primary oxidation products are treated with an afterburner to destroy any remaining trace organic components, and acid gases (HF, HCl, P2O5, and SO2) are neutralized and removed in the gas cleanup system.2 2 The mineralized oxidation products from halogens, phosphorus, and sulfur are all acidic and readily removed from gas streams by alkaline scrubbers, leaving CO2 and water vapor as the principal gaseous wastes. However, the gas scrubber effluents must be monitored and disposed of as hazardous wastes. All of these can be reacted with lime at high temperatures to avoid liquid wastes.
