Authors: Yakup Nurdogan, Craig Myler, George Lecakes, Paul Usinowicz, Eric Blumenstein

The Pueblo Chemical Agent-Destruction Pilot Plant is being constructed for demilitarization of chemical weapons stored at the U.S. Army Pueblo Chemical Depot, Pueblo, Colorado. The Pueblo stockpile consists of projectiles and mortars filled with blister agents (93.4% of total stockpile), explosives (4.2%), and propellants (2.4%).

Agents contain approximately 98% distilled mustard, β,β’-dichloroethylsulfide. 2% is a mixture of distilled mustard and bis 2-2-chlorethylthioethyl ether. The process chosen for demilitarization involves collection of the chemical agent from the munitions, hot water hydrolysis of the agent to produce an agent-free hydrolysate, caustic neutralization of hydrolysate, biological treatment of the hydrolysate to reduce organic content, and effluent treatment to separate salts and recover water for reuse. The biological process selected for hydrolysate treatment is the Immobilized Cell Bioreactors.

This paper will describe the design of the bioreactors for use at the Pueblo Chemical Depot. The design is based on laboratory and pilot testing results, which provided determination of organic loading rates, hydraulic retention times, aeration and nutrient requirements, operational parameter ranges and controls (temperature, dissolved oxygen, and pH).

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