Ammonium nitrate solution (ANSOL), a mixed waste stream byproduct from the production of energetic materials, contains residual explosive content and toxic metals that require it to be treated as hazardous waste under the Resource Conservation and Recovery Act (RCRA). Although its composition depends on the particular production operations, ANSOL is usually comprised of ammonium nitrate, amine nitrates, water, nitramine explosives (RDX, HMX), decomposition products, and high levels of trace contaminants, particularly chromium, that pose long term health risks for potential reuse or disposal of ANSOL.

To combat this issue, SERDP is investing in the development of processes to convert ANSOL into useful products. The following four efforts have been selected for funding in 2021 to develop innovative and cost-effective processes for transforming ANSOL:

• At the U.S. Naval Laboratory, Dr. Igor Medintz will demonstrate the proof-of-concept that ANSOL can be converted into useful industrial feedstock, like amino acids and some of their non-natural analogs, by applying significant bioenzymatic remediation. This project will provide valuable data on nanoparticile-immobilized enzymatic catalysis for converting ANSOL into useful products. (Project Overview)

• A project led by Dr. Philip Larese-Casanova at Northeastern University will explore the potential for electrochemical and adsorption technologies to selectively remove nitramine compounds and chromium from ANSOL to develop a purified, salable product. His team will develop a three-stage purification system and a technology that generates a variety of nonspecific reductants and oxidants that are applicable to any nitramine compound. This project will also provide valuable insights to nitramine and chromium transformation processes. (Project Overview)
• Dr. David Jassby with University of California, Los Angeles and his team will demonstrate an electrochemical transformation process for ANSOL using electrically conducting membranes that produce ammonia and nitric acid, destroy high energy compounds, and remove chromium. Because electrochemical reactions can be carried out across an expansive temperature range, his team will be able to test ANSOL treatment across this range and determine the economic viability of this process with a range of product endpoints. Additionally, this project will improve understandings of electrochemistry-assisted separation processes, which have the potential to transform other waste streams into useful products. (Project Overview)
• Dr. Sarah Headrick with BAE Systems and her team will address ANSOL reuse at the Holston Army Ammunition Plant by purifying ANSOL product through a combination of adsorbent resin treatment and crystallization of ammonium nitrate. The second task will be to evaluate the isolated solid ammonium nitrate for use in synthesis reactions to produce RDX and HMX. (Project Overview)

Converting ANSOL into products of use would benefit program managers and installations across all services. As more information becomes available, individual web pages for these projects will be updated with reports and related work documenting their progress.