Advanced Oxidation Processes (AOP)
Advanced Oxidation reactions are an extension of the process whereby UV alone is used to reduce Total Organic Carbon (TOC) through the lysing of water molecules into hydroxyl radicals. Hydroxyl radicals (•OH) are produced with the help of one or more primary oxidants (usually ozone or hydrogen peroxide) and ultraviolet light. This reactive species is the strongest oxidant that can be applied in water and can oxidize virtually any compound present in the water. Hydroxyl radicals react unselectively once formed and contaminants will be quickly fragmented into small inorganic molecules. In general, when applied in properly controlled conditions, AOPs can reduce the concentration of contaminants from several hundred ppm to less than 5 ppb. The overall process often leads to mineralization (i.e. conversion to CO2, H2O and mineral acids) of the pollutants. The processes are called “Advanced” because the overall reactions of pollutants are the same as slow degradation reactions occurring in the environment, but are highly accelerated. AOPs are often used in treating industrial and municipal water to remove biologically toxic or non-degradable materials such as aromatics, pesticides, petroleum constituents and volatile organic compounds.