Challenge

Ratification by the U.S. Congress of the Chemical Weapons Convention requires the destruction of all chemical warfare materiel (CWM). The U.S. Army Program Manager for the Elimination of Chemical Weapons oversees destruction of the U.S. CWM stockpile, and has established the Non-Stockpile Chemical Materiel Program (NSCMP) for destruction of non-stockpile chemical warfare material.

The NSCMP is responsible for the destruction of binary chemical weapons; former production facilities; miscellaneous chemical warfare material; recovered chemical weapons; and buried chemical warfare material; and is committed to investigating non-incineration based technologies.

Stone & Webster, a Shaw Group company, has been contracted to investigate dozens of treatment technologies for fulfilling this commitment, and in 2001, contacted Siemens Water Technologies to test the Zimpro® wet air oxidation (WAO) system on neutralized feeds.

Solution

WAO was studied extensively on the waste streams in a laboratory and pilot plant setting. The test program included the bench testing of four possible chemical feeds.

The WAO process is a low-temperature, liquid-phase, flameless process for the destruction of toxic and waste materials. It is a liquid phase reaction in water using dissolved oxygen to oxidize wastewater contaminants. Oxidation reactions generally occur at moderate temperatures of 150°–320°C (275°–610°F) and at pressures from 150 to 3200 pounds per square inch (10 to 220 bar). The process converts organic contaminants to carbon dioxide, water, and biodegradable short chain organic acids. Inorganic constituents such as sulfides and cyanides are also destroyed.

Siemens Water Technologies performed three phases of testing in the prospective feeds in this case, including batch autoclave WAO treatment and materials of construction tests on simulants of each of the four candidate feeds; continuous flow pilot testing of neutralized mustard simulant; and continuous flow pilot treatability and materials of construction testing on neutralized nerve agents and precursors.

Overall objectives of the project were to:

• demonstrate process efficacy for treatment of the NSCMP feeds.
• demonstrate safe, steady state, continuous operation of the pilot plant.
• evaluate the performance of the materials of construction.
• develop engineering data for future full-scale development.

Results

WAO was found to be a suitable treatment process for treating neutralized chemical warfare material feeds. Successful treatment of each feed was demonstrated in the laboratory and in the continuous flow pilot plant, and a suitable material of construction was identified and tested.

Wet Oxidation was then applied as a suitable alternative to incineration to the wastestreams generated by the destruction of the chemical warfare material. Click here to read about how Wet Oxidation solved the destruction requirements of the Non-Stockpile Chemical Materiel Program (NSCMP).