Removal of Emerging Contaminants in Waste-water Treatment: Removal by Photo-catalytic Processes

Abstract

Although advanced oxidation processes (AOPs) are well known for their capacity to oxidize and mineralize almost any organic contaminant, commercial applications are still scarce. Future applications of these processes could be improved through the use of catalysis and solar energy. Therefore, their investigation increasingly focuses on the two AOPs that can be powered by solar radiation (i.e. light with a wavelength greater than 300 nm), namely homogeneous catalysis by the photo-Fenton reaction and heterogeneous catalysis by the UV/TiO₂ process. This work summarizes the main characteristics of both photo-Fenton and heterogeneous photo-catalysis, noting the main advantages and drawbacks, and focuses mainly on applications related to emerging contaminants. The solar photo-catalytic degradation of these new environmental contaminants, many of which had been unknown until recently, is the focus of a great deal of research. The work also comments on different technological issues that should be taken into account and points out the distinctiveness of each treatment, on a case by case basis: MTBE, lincomycin, diclofenac, and dipyrone.