Advanced Reduction and OxidationReduction Processes for Water Treatment

AbstractOxidationreduction reactions are important processes for water treatment because they chemically change contaminants, rather than only transfer them from the water phase. However, the rates of many oxidationreduction reactions limit their use as treatment processes. This limitation can be overcome by using highly reactive free radicals as the chemical reductant, and treatment processes that do this can be called advanced reduction processes (ARPs). Treatment processes that rely on both oxidizing and reducing radicals can be called advanced oxidationreduction processes, and both are similar to advanced oxidation processes that apply oxidizing radicals to water treatment. This article reviews a number of applications of ARPs and summarizes the characteristics of some AORPs. ARPs have been applied to a wide range of contaminants including halogenated organics and oxidized inorganic compounds. The effects of important process variables such as incident photon flux, reagent concentration, target compound concentration, and solution pH are reviewed for ARPs, and a simple kinetic model is presented that describes much of their behavior that has been observed. The basic aspects of two important AORPs (electron beam irradiation and photocatalysis) are discussed, and a kinetic model describing the dose coefficient for electron beam treatment is presented.

Advanced Reduction and OxidationReduction Processes for Water Treatment Chapter