Munitions constituents manufacturing and load/assemble/pack (LAP) operations generate liquid waste streams from various plant activities. Manufacturing generates wastewater containing both organics (munitions constituents) and inorganics (nitrate). The waste stream volume is lower and more easily handled during the initial munitions constituents development and test stage than during the acquisition stage, where flows as high as five million gallons a day may be generated. For LAP operations, the volumes also tend to be smaller, and the main constituents are munitions constituents, with traces of processing agents. While efforts are made to keep solid munitions constituents out of the liquid waste stream using crystallization, settling, and filtration, the presence of micron-sized munitions constituents is still probable.
The established treatment trains at specific manufacturing and LAP facilities vary, but some generalizations can be made. Manufacturing facilities tend to use sequential anaerobic/aerobic biological treatment to remove both the inorganic nitrate and the organic munitions constituents using traditional wastewater treatment plant processes, with discharge to surrounding surface water. While these processes have been reasonably effective for treating manufacturing wastewaters containing legacy munitions constituents (e.g., TNT, RDX, HMX, DNT, nitrocellulose), a stricter regulatory environment and the need to produce a range of new munitions constituents, including IHE like NTO, DNAN, and NQ, is putting demands on existing systems. For instance, while the legacy munitions constituents are considered to be not very soluble (e.g., 10’s to 100’s mg/L), newer IHE constituents like NTO have a solubility of 20,000 mg/L, leading to both high concentration wastewater and a much larger loss of the end product to the waste stream. Additionally, while legacy munitions constituents are amenable to the current biological treatment approaches, not enough is known about the degradative pathways of IHE to assure the existing wastewater treatment trains will be sufficient to meet release criteria.
LAP facilities tend to use diatomaceous earth filters combined with granular activated carbon (GAC), and run their processing water in closed loops through the plant (e.g., zero discharge), with spent GAC removal and disposal as a hazardous waste. It is likely that the more highly soluble IHE (like NTO and NQ) will sorb less to GAC than the legacy munitions constituents, thereby reducing the effectiveness of the existing LAP wastewater treatment process, and requiring new technologies to ensure effective IHE treatment.
The co-manufacturing of both legacy munitions constituents (e.g., RDX) and newer IHE (e.g., NTO) is expected to continue for several decades. Additionally, new IHE are continually being developed. Therefore, technologies capable of handling mixed waste streams are a critical need. Workshop participants identified a number of research needs associated with improved treatment of wastes from manufacturing of munitions constituents. It is essential that proposers view the Workshop Report to obtain additional detail concerning these discussions.
