Photochemical advanced oxidation processes for water and wastewater treatment

Abstract

Advanced Oxidation Processes (AOPs) are excellent systems for remediation of contaminated wastewaters containing recalcitrant organic pollutants. The most studied AOPs are photochemical-based processes (PAOPs), as UV/hydrogen peroxide, heterogeneous photocatalysis (HP), photo-Fenton (PF), UV plus ozone and combination of these technologies. All AOPs are based on the production of very reactive species (especially hydroxyl radicals, HO•) able to degrade or transform chemical pollutants, provoking ultimately total mineralization. One of the major drawbacks of AOPs is that the operational costs are relatively high compared to less expensive technologies such as biological treatments, use of activated carbon, etc. However, these technologies can be used combined with themselves or with conventional technologies. In spite of a huge amount of scientific publications, applications and patented methods on PAOPs are scarce. In this article, a brief review on the most used PAOPs, together with recent patents on the field are presented. The patents describe mostly inventions on HP and PF, most of them using catalysts supported on membranes, perovskites, zeolites or other materials, and combination of PAOPs with conventional technologies.