Advanced Oxidation Processes

Oxidation is defined as the transfer of one or more electrons from an electron donor (reductant) to an electron acceptor (oxidant), which has a higher affinity for electrons. These electron-transfers result in the chemical transformation of both the oxidant and the reductant, in some cases producing chemical species with an odd number of valence electrons.

These species, known as radicals, tend to be highly unstable and, therefore, highly reactive because one of their electrons is unpaired. Oxidation reactions that produce radicals tend to be followed by additional oxidation reactions between the radical oxidants and other reactants (both organic and inorganic) until thermodynamically stable oxidation products are formed.

The ability of an oxidant to initiate chemical reactions is measured in terms of its oxidation potential. The most powerful oxidants are fluorine, hydroxyl radicals (•OH), ozone, and chlorine with oxidation potentials of 2.85, 2.70, 2.07 and 1.49 electron volts, respectively. The end products of complete oxidation (i.e., mineralization) of organic compounds such as benzene etc are carbon dioxide (CO2) and water (H2O).

Applications include:
• Oxidation of inorganic species (ferrous iron, manganous manganese, sulphides)
• Oxidation of various organic compounds (NOM and organic pollutants)
• Oxidation of odorous organic compounds (geosmin and 2-Methylisoborneol)
• Oxidation of chlorinated organic compounds
• Improve the performance of / reduce the required coagulant dosage
• Control nuisance aquatic growth of for instance algae
• Disinfection of various microorganisms

Advantages Of AOP Are:
• Rapid reaction rates and relatively small footprint
• Potential to reduce toxicity and possibly complete mineralization of organics treated
• Destruction of numerous organic compounds
• Established technologies for drinking water treatment
• Non selective pathway allows for the treatment of multiple organics
• Improvement of Biodegradability in Pre-Treatment
• Toxicity Removal
• Secondary disinfection capability