The US military is increasing use of insensitive munitions that are less sensitive to shock and high temperatures thus avoiding unintentional detonation. Manufacturing and load/assemble/pack (LAP) of munitions containing IMX 101, IMX 104 and PAX-21 generate wastewater with mixtures of legacy and new insensitive high explosives such as DNAN (2,4-dinitroanisole), NTO (3-nitro-1,2,4-triazol-5-one), NQ (nitroguanidine), RDX, and ammonium perchlorate. These wastewaters present a challenge for existing treatment plants as more soluble compounds such as NTO are less likely to adsorb to activated carbon and various munitions have been shown to interfere with one another during biological degradation or ion exchange. Additionally, some of these compounds require a sequence of anaerobic and aerobic environments to completely degrade to non-toxic end products and the need for this sequence complicates bioreactor design. Research is needed to elucidate the most cost effective and efficacious treatment technologies for these challenging waste streams. Cost effective and efficient wastewater treatment trains are needed to meet stringent wastewater discharge requirements imposed on Department of Defense (DoD) manufacturing and LAP facilities. The objective of this project is to study various treatment systems to determine the most efficient and cost effective treatment train employing an integration of biotic and abiotic approaches to accomplish nearly complete remediation of target munitions.

Ion Exchange and Granular Reactor Treatment Trains for Combined IX-Brine Bioregeneration for Wastewater Containing NTO.

Granules Capable of Mineralizing Munitions Containing Wastewater

This project will first evaluate chemical and physical separation processes (ion exchange and low pressure membranes) for munitions segregation into biologically treatable streams, and second high rate granulation based, innovative biological treatment of segregated munition constituents and bioregeneration of ion exchange (IX) brines. This project will study various treatment systems previously shown to treat the individual munitions constituents and leverage prior research on interferences among constituents when mixed in wastewater. Specifically, it will test two treatment trains utilizing physical, chemical and biological treatment technologies. First, it will test (1) chemical adsorption of perchlorate, nitrate and NTO to anion exchange resins with recharge of the IX resin with salt brines, (2) bioregeneration of the IX brine to reduce treatment cost, by biological treatment of perchlorate, nitrate and NTO in the brine in innovative halophilic enriched, high rate granular reactors, and (3) anaerobic granular reactors for treatment of IX flow through containing RDX, DNAN, and NQ. Simultaneously, the project will also evaluate the other most technically feasible treatment system (1) physical separation of perchlorate and nitrate from mixed munitions wastewater in reverse osmosis (RO) permeate, (2) biologically treat perchlorate and nitrate in reverse RO permeate with anaerobic, high rate granular reactors, and (3) biologically treat RO retentate containing RDX, DNAN, NQ, and NTO in aerobic/anaerobic granular reactors.

Schematic Diagram of Treatment Train

This project will test the most technically feasible and economically viable technologies for mixed munitions wastewater. It will use prior research results, current literature, and state of the knowledge of munitions wastewater to test cost effective and efficient treatment technologies to achieve stringent discharge limits for munitions wastewater from DoD facilities. The inclusion of innovative biological treatment with high rate granular reactors and anion exchange resins for NTO is novel and will advance the state of the science. Inclusion of a DoD wastewater advisory board will ensure realistic design of treatment trains and provide the DoD with timely and transparent performance data regarding available treatment systems. (Project Completion - 2023)

Cavanaugh, S., P. Smith, and J. Weidhaas. 2022. Experimental Diffusivity of Energetic Compounds Determined by Peak Parking. Journal of Hazardous Materials, 424(D):127681. doi.org/10.1016/j.jhazmat.2021.127681.

Cavanaugh, S. J. and J. Weidhaas. 2023. Response Surface Methodology for Performance Evaluation of Insensitive Munitions Wastewater Membrane Filtration. Cleaner Engineering and Technology, 12:100603. doi.org/10.1016/j.clet.2023.100603.

Stein, N., A. Goswami, and R. Goel. 2023. Anoxic Granular Activated Sludge Process for Simultaneous Removal of Hazardous Perchlorate and Nitrate. Journal of Hazardous Materials, 485: 131809. https://doi.org/10.1016/j.jhazmat.2023.131809.

Stein, N., A. Podder, J. Weidhaas, and R. Goel. 2022. Simultaneous Reduction of Perchlorate and Nitrate using Fast-Settling Anoxic Sludge. Chemosphere, 286(2):131788. doi.org/10.1016/j.chemosphere.2021.131788.

Stein, N., A. Podder, and R. Goel. 2023. Biodegradation of Insensitive Munition (IM) Formulations: IMX-101 and IMX-104 using Aerobic Granule Technology. Journal of Hazardous Materials, 449:130942. doi.org/10.1016/j.jhazmat.2023.130942.

Tran, D. and J. Weidhaas. 2022. Ion Exchange for Effective Separation of 3-Nitro-1,2,4-triazol-5-one (NTO) from Wastewater. Journal of Hazardous Materials, 436:129215. doi.org/10.1016/j.jhazmat.2022.129215.

Zebelean, D., D. Tran, R. Goel, and J. Weidhaas. 2023. Halophilic Biodegradation of 3-Nitro-1,2,4-triazol-5-one (NTO) in Brine. Journal of Environmental Engineering, 149(9). https://doi.org/10.1061/JOEEDU.EEENG-7319.