Chapter 6 - Advanced Oxidation and Reduction Processes

Abstract

Water contamination by micropollutants, such as pesticides, pharmaceuticals and personal care products (PPCPs), polycyclic aromatic hydrocarbons (PAHs), perfluorinated compounds (PFCs), surfactants, plasticizers, and pathogens is a global issue of immense attention, owing to the frequency of incidences of waterborne diseases, including human deaths. Advanced oxidation processes (AOPs, e.g., photolysis, photochemical, photocatalysis, cavitation, and electrochemical processes), advanced reduction processes (ARPs, e.g., UV/sulfite process), or combined advanced oxidation/reduction processes (AO/RPs, e.g., electron beam and gamma radiation), have emerged to be very promising for the degradation of micropollutants. This review describes the fundamentals of AOPs, ARPs, or combined AO/RPs for water decontamination. Factors affecting the efficiency of AO/RPs, including solution pHs, initial concentrations of pollutant, the presence of natural organic matter and inorganic ions, dissolved oxygen, oxidant concentrations and catalyst loadings, dose rates, and wavelength and intensity of light, are discussed. The mechanisms of pollutant degradation by AO/RPs are described. Recent advances, current challenges and future opportunities in the field of AO/RPs are addressed. Pilot-plant studies and full-scale extension of AO/RPs toward water purification are also discussed, considering practical applications. Cost comparison of various AO/RPs is also made according to the data provided by various suppliers. It is concluded that AO/RPs are promising in the decontamination of water, especially for selected applications.