UV/peroxide treatments

In 1994, Rayox developers generated cost estimates for the technology based on bench-scale studies. Using a proposed cleanup site in Canada as a model, researchers compared these estimates with the costs of using an air stripper/liquid carbon/catalytic oxidizer (air/carbon) option. Results indicated that UV/peroxide treatment, with or without an iron catalyst, was found to have an estimated capital cost equal to the air/carbon option at the site (D12302U). 

At the Brown and Bryant Superfund Site, in Arvin, California, soil washing operations resulted in the production of 100,000 gal of wash water containing 400 to 600 ppm of Dinoseb. A Rayox system was implemented at the site that used ozonation followed by UV/peroxide treatment. The operating cost for this project was 40 per 1000 gal (D17097S, Appendix II). 

Commercially viable systems for the decolorisation of spent dyebaths can be based on hydrogen peroxide treatment initiated by UV radiation. A representative selection of six disulphonated monoazo acid dyes and two disazo disulphonated types was exposed for various times in a pilot-scale photochemical reactor of this kind. The controlling parameters were dye structure, pH, peroxide dosage and UV light intensity [39]. In a wider survey of the response of various classes of dyes to the combination of UV radiation and hydrogen peroxide, viable candidates for further in-plant treatment trials were the water-soluble reactive, direct, acid and basic classes. On the other hand, water-insoluble colorants such as disperse and vat dyes did not appear to be viable [40]. 

Adams, C.D., Fusco, W., and Kanzelmeyer, T., Ozone, hydrogen peroxide/ozone and UV/ozone treatment of chromium- and copper-complex dyes decolorization and metal release, Ozone Sci. Eng., 17, 149-162, 1995. 

Fig. 3 Treatment of Hispamin Black CA by UV(366nm)/peroxide (a) Variation of the normalized absorption at 471 nm with irradiation time under UV irradiation and under UV irradiation in the presence of hydrogen peroxide (b) variation of TOC during reaction with UV/peroxide. Conditions [Hispamin Black CA] = 40 mg L-1, pH 7.5, [H202] =565.8 mg L-1 [27]...

Trichloroethylene is mixed with an excess of combustible solvent and burned in a chemical incinerator equipped with an afterburner and scrubber. It may be destroyed in aqueous waste streams or groundwater by UV peroxidation, involving treatment with hydrogen peroxide in the presence of UV light (Yost 1989 Sundstrom et al. 1990). Oku and Kimura (1990) have reported reductive dechlorination using sodium naphthalenide in tetrahydrofuran at 0°C for 10 minutes. Chlorine is removed as sodium chloride to the extent of 97-100%. 

UV radiation is used to produce hydroxyl radicals (for example, by homolytic splitting of hydrogen peroxide) and in some cases for the degradation of compounds sensitive to UV radiation. When colored chemicals are present (dyes, for example) solar light could be used, with the dye also acting as photosensitizer. The costs of UV radiation treatment processes are largely dependent on the absorption properties... 

In a simple approach, monomers of the guest polymer are first impregnated into a preformed porous silicate film, and subsequently polymerization is initiated either by a free radical initiator (UV, peroxides), by thermal treatment, or by electrochemical means. On the positive side, this procedure is favorable for the incorporation of linear polymers in silicates, but on the downside, some of the major advantages of composites, such as biocompatibility and adhesion to the substrate, are lost. The polymerization of organic moieties within the interconnected pores of the organic material can be carried out by two general methods that are addressed in the following text. 

Hydrogen peroxide can also be activated by ultraviolet radiation or o2one and ultraviolet radiation (178,188,189). One of the most active fields in waste treatment is ultraviolet-cataly2ed oxidation with hydrogen peroxide (190—194). The uv light activates the hydrogen peroxide converting it to hydroxyl radicals (195). 

Another cleaning process for the removal of tetrahydrothiophene process uses an advanced oxidation technique, consisting of water treatment by UV-radiation in combination with a dosage of hydrogen peroxide [1392]. It is possible to keep the concentrations of odorant and condensate in the effluent below 0.1 ppb. 

AOPs are less appropriate for the complete treatment of wastewater streams containing high concentration of organic pollutants. The main reason is that the energy costs and costs of chemicals such as ozone and hydrogen peroxide are relatively high. In case of UV also the equipment costs may be substantially. To treat these concentrated waste streams the application of AOPs has to be focused on the selective oxidation of specific toxic pollutants or on the partial oxidation of pollutants. 

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