In comparison to other water treatment technologies, advanced oxidation processes (AOPs) offer the opportunity to completely convert hazardous substances into carbon dioxide, water and salts without producing residues. However, a key challenge is to combine them with other unit operations in order to increase overall process efficiency: AOPs' most significant disadvantages are high energy consumption and the possibility of producing critical intermediates. New knowledge in the production of oxidative species with higher yields, reaction pathways, reactor design, process combination, determination of hazardous intermediates by e.g. genetic test methods, as well as applications for water reuse were amongst the subjects of nearly 150 papers presented at the fourth AOP conference; a particular focus was the elimination of recalcitrant and anthropogenic micro-pollutants even at low concentrations from municipal and industrial effluents, a most promising application for AOPs.
This issue contains 49 papers, selected after full peer review and grouped according to subject area: process fundamentals; Fenton reactions; photocatalysis; applications; disinfection; process combinations; innovations and special topics. They represent the most recent advances in research into the fundamentals as well as the development and the application of advanced oxidation technologies in water and wastewater treatment.