Pesticide chemical oxidation: state-of-the-art

The various currently used chemical oxidation processes (AOPs), for pestici de elimination from wastewater are reported. Heterogeneous TiO2 pholocataly sis, ozonation and photo-Fenton's reagent are the most intensively investig ated technologies. Theoretical and practical advantages and limitations of each method are discussed. Degradation mechanism and experimental condition s employed for the optimization of each technology are reviewed. Performanc es such as the achieved degree of mineralization and obtained degradation r ates are detailed. The various analytical approaches for studying pesticide degradation by AOPs are also discussed. Formation of by-products is unavoi dable during cost effective treatments. Their detection and identification are required in order to determine which kind of chemical structures are le ft at the end of the process. For this purpose, the crucial role of gas and liquid mass spectrometry is emphasized. The review reveals a general lack of data on kinetics of formation and disappearance of the major by-products . The efficiency of AOPs has scarcely been investigated at industrial scale s, i.e. in presence of a mixture of active ingredients together with their formulating agents and at concentration levels above 10 mg/l. The more pola r by-products are largely unknown and their toxicity is usually not address ed. (C) 1999 Elsevier Science Ltd. All rights reserved.