Common Treatment Technologies for Explosives in Ground Water, Surface Water, and Leachate

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Explosives-contaminated process waste waters can be subdivided into two categories: red water, which comes strictly from the manufacture of TNT, and pink water, which includes any washwater associated with load, assemble, and pack (LAP) operations or with the demilitarization of munitions involving contact with finished explosive. Despite their names, red and pink water cannot be identified by color. Both are clear when they emerge from their respective processes and subsequently turn pink, light red, dark red, or black when exposed to light. The chemical composition of pink water varies depending on the process and explosive operation from which it is derived; red water has a more defined chemical composition. For this reason, it is not possible to simulate either red or pink water in the laboratory.

The United States stopped production of TNT in the mid-1980s, so no red water has been generated in this country since that date (Hercules Aerospace Company, 1991). Most process waters found in the field are pink waters that were generated by LAP and demilitarization operations conducted in the 1970s. In these operations, munitions were placed on racks with their fuses and tops removed. Jets of hot water then were used to mine the explosives out of the munitions. The residual waters were placed in settling basins so that solid explosive particles could be removed, and the remaining water was transferred into lagoons. Contaminants often present in these lagoon waters and the surrounding soils include TNT, RDX, HMX, 2,4-DNT, 2,6-DNT, 1,3-DNB, 1,3,5-TNB, and nitrobenzene.

These past waste-handling practices at explosives manufacturing and LAP plants often used unlined lagoons or pits to contain process wastewaters. As a result of this practice, some explosive residues have leached through the soil and contaminated ground water. Therefore, ground water treatment may be required. Based upon process wastewater treatment experience, potentially applicable treatment technologies are available. However, the similarities and differences between process wastewaters and explosives-contaminated ground water should be considered before transferring technologies from one application to another.

Granular-activated carbon (GAC) adsorption is commonly used for explosives-contaminated ground water treatment. GAC does not work for red water treatment.

In the 1980s, the Army discontinued the practice of disposing of untreated process waters from the production and maintenance of munitions in open lagoons. Every Army ammunition plant currently employs some type of GAC system to treat process waters as they are generated. GAC is very effective at removing a wide range of explosive contaminants from water.

GAC can be used to treat explosives-contaminated water, including process waters from the manufacture and demilitarization of munitions (pink water) and ground water contaminated from disposal of these waters.

Ultraviolet (UV) oxidation has not been used extensively for remediating water contaminated with explosives because of the widespread use of GAC treatment. Nevertheless, UV oxidation can be an effective treatment for explosives-contaminated water and, unlike carbon treatment, actually destroys target compounds rather than just transferring them to a more easily disposable medium. UV oxidation can be used to treat many types of organic explosives-contaminated water, including process waters from the demilitarization of munitions (pink water) and ground water contaminated from disposal of these process waters.

USAE-WES is evaluating a perozone system for explosives-contaminated ground water treatment. This system uses hydrogen peroxide and ozone to oxidize explosive constituents without UV light. The perozone system may offer economic advantages in UV oxidation systems.

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