UV紫外线杀菌器在水和废水处理中的应用英文原版研究论文_C04.pdf

4 Use of Ultraviolet in Photochemical Synergistic Oxidation Processes in Water Sanitation 4.1 BASIC PRINCIPLES 4.1.1 GENERAL Photochemical synergistic oxidation processes are a recent development in water treatment, related to the necessary removal of pollutants that are resistant to the more classical methods of treatment. The techniques, still in further development, are often termed commercially advanced oxidation processes (AOPs). Besides the chemistry specifically related to ozone (for an overview, see Hoigné [1998]), these technologies involve several aspects related to the application of ultraviolet (UV): • Direct photolytic action on compounds dissolved in the water sources • Photochemically assisted production of oxidants (mainly supposed to be hydroxyl free radicals) • Photochemically assisted catalytic processes Although effects have been observed on the ground, it must not be forgotten that an overall energetic balance is required. Considerable amounts of data have been reported in the literature related to water treatment, both in laboratory experiences, pilot plant investigations, and full- scale applications. However, even when the conditions and methods applied have been described with precision, it is often not possible to formulate general guidelines for design from the positive evidence as reported. These oxidation methods are applicable for the removal of compounds resisting the more classical techniques. This effect is often considered as secondary in technical literature. More investigation on this subject is required. It certainly plays a role in combined ozone-UV processes [Denis et al., 1992; Masschelein, 1999; Leitzke and Friedrich, 1998]. The aim of this ch