Static and Continuous flow-through pulsed light technology for pesticide abatement in water.

Perspectives concerning pulsed light (PL) technology as a novel water decontamination treatment are overviewed in this work. Degradation of atrazine, malathion, chlorpyriphos-methyl and bromopropylate in aqueous solutions at different concentrations was performed employing static and continuous flow-through PL units. Results for both PL systems were compared in terms of efficacy of pesticides degradation and derived photoproducts formed. The pesticides degradation increased with the applied total fluence for both PL systems. In general, PL induced rapid degradation of all studied compounds although some differences were observed in the rate of degradation among them. The most intense treatment in the static unit (11J/cm) yielded degradations between 60 and 85% whereas degradations between 74 and 93% were observed after exposure to slightly lower fluences (10J/cm) in the dynamic unit. For both PL systems bromopropylate was the most affected compound. Photodegradation products arose from chemical reactions involving structural changes like dehalogenation, desulfuration, dealkylaytion and oxidation of the alkyl chains. Although further research is needed before an efficient application in full-scale systems, PL appears as a promising technology in order to reduce the presence of pesticides residues in process or waste waters, allowing thereby recirculation of these waters with the subsequent economic and environmental advantages.