Ultraviolet oxidation

Ultraviolet (UV) oxidation has not been used extensively for remediating water contaminated with explosives, because of the widespread use of granular activated carbon (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-con-taminated water, including process waters from the demilitarization of munitions (pink water) and groundwater contaminated from disposal of these process waters. 

In 1981, the Army conducted a pilot-scale study of UV oxidation for treating waters from the Kansas AAP contaminated with RDX. RDX concentrations in the process water ranged from 0.8 to 21.0 mg/l. The UV oxidation system consisted of thirty 40-watt, UV lamps, and an ozone generator, which provided ozone to the treatment process. Treatment times in this system ranged from 37 to 375 minutes at flow rates of 0.2 to 2.0 gpm. Final RDX concentrations in the effluent ranged from 0.1 to 1.7 mg/ , which would not have met current regulatory criteria. 

Similar studies have been conducted at Crane AAP, Iowa AAP, Holston AAP, and Picatinny Arsenal. It is difficult to compare performance data from these studies, however, because each study operated under different treatment conditions. Some used 40-watt, low pressure, UV bulbs others used 65-watt, medium pressure, UV bulbs. Some amended the water with hydrogen peroxide (HjOj) others did not. The studies also used different concentrations and species of contaminant, different total residence times, and different concentrations of ozone. In addition, some of the studies used simulated pink water, which usually lacks many of the constituents of real pink water. 

UV oxidation is being considered at Picatinny Arsenal for the treatment of groundwater containing 6.0 ppb of RDX. The Waterways Experiment Station in Vicksburg, Mississippi ran a pilot test on the proposed UV oxidation system and a parallel test of an activated carbon system to compare the economic feasibility of the two. 

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U.S. Environmental Protection Agency, demonstration Bulletin CAW-OX Ultraviolet Oxidation Process, Magnum Water Technology, EPA/540/MR-93/520, Cincinnati, Ohio, 1993. 

Both the persulfate and ultraviolet oxidation methods have much to recommend them. Ultraviolet photo-oxidation methods have an advantage in that they are easily automated. 

Williams [81,84] found that a high-energy ultraviolet oxidation method gave dissolved organic carbon results for seawater samples that were higher than those obtained by the wet persulfate oxidation method described by Menzel and Vaccaro [46]. Other variations on the method have been published. 

UVOX [Ultraviolet oxidation] A process for purifying seawater before clarification, using chlorine and exposure to sunlight. Developed in South Africa. 

As mentioned above, many variants of the Dohrmann total organic carbon analyser are available, ranging from low-cost non-automated analysers based on sample combustion in a platinum boat (DC8JA) or using persulphate oxidation/ultraviolet irradiation (DC 88) to top-of-range fully automated and computerized systems based on combustion in a ceramic tube (DC 90) or combined simultaneous persulphate-ultraviolet oxidation (DC 180). Only one of these systems, the DC 180, is discussed below in any detail. 

Pollution of soils and waters by human activities is an important and widespread problem. This pollution by, organic and inorganic substances can affect individual organisms, human populations, and ecosystems, each in its own unique way. In particular former military installations, often used for weapons production and nuclear power plants represent a ongoing and substantial threat to environment and human health because of the specific pollutants that can be released Solvents, explosives, fuels, radionuclides, heavy metals, and metalloids all have been identified in the environment around these installations. Remediation technologies for these contaminated sites have been developed based on conventional systems utilising physical and chemical treatments, such as excavation and incineration, pump-and-treat methods, ultraviolet oxidation, soil washing, etc. 

Figuro 12 Ultrox ultraviolet/oxidation process flow schematic. Equipment includes an O3 generation and feed system and an oxidation reactor mounted with UV lamps inside H2O2 feed is optional. (Courtesy of Ultrox International.)...

T0833 Ultraviolet Oxidation (UV/Oxidation)—General T0853 UV Technologies, Inc., UV-CATOX Technology T0855 Vapor-Phase Biofiltration—General... 

T0826 U.S. Filter/Zimpro Products, Powdered Activated Carbon Treatment (PACT) T0833 Ultraviolet Oxidation (UV/Oxidation)—General... 

T0728 Solox, Hybrid Solar/Electric Ultraviolet Oxidation System T0732 Solvent Extraction—General... 

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