Influence of chloride concentration on the formation of AOX in UV oxidative system

In this study, the effects of chloride ion concentration and pH on UV oxidation treatment were examined. Acetone and sodium dodecyl sulfate (ABS) were used as organic substances. The treatment efficiencies of these chemicals by UV/H2O2 oxidation using a laboratory scale UV-free surface reactor (UV-FSR) with or without Cl- addition at different pH values was compared. Results of this study indicated that Cl- concentration and the chemical structure of the substances are more decisive than pH in the oxidation process. There was no AOX at the start of the experiments but as a result of oxidation a de novo synthesis of AOX was observed, and these AOX(de novo) compounds were destroyed during the treatment. Treatment was followed by TOC and AOX measurements. Approximately 98% and 95% TOC removal efficiencies were obtained for the treatment of acetone and ABS containing wastewaters, respectively. (C) 2006 Elsevier B.V. All rights reserved

Effect of chloride concentration on the oxidation of EDTA in UV-FSR oxidative system

This study focused on the effect of chloride concentration and pH on the photochemical degradation of ethylenediaminetetraacetic acid-disodium salt (C10H14N2Na2O8 center dot 2H(2)O, EDTA) under advanced oxidation using UV/H2O2 system. The treatment of this chemical by UV/H2O2 oxidation using a laboratory scale UV-free surface reactor (UV-FSR) with (1000 and 10,000 mg/l Cl-) and without Cl- addition at different pH values (pH 3, 7 and 10) was compared. Results of this study indicated that Cl- concentration is more decisive than pH in the oxidation process. There was no AOX at the start of the experiments but as a result of oxidation a de novo synthesis of AOX was observed, and these AOX(de novo) compounds were destroyed during the treatment. Treatment was followed by TOC and AOX measurements. Approximately 95% TOC removal efficiency was obtained for the treatment of EDTA-containing synthetic water. Owing to kinetic studies, it was found that the TOC degradation in all experiments fitted to the first order reaction law. (C) 2007 Elsevier B.V. All rights reserved