Measurement of the initial phase of ozone decomposition in water and wastewater by means of a continuous quench-flow system: application to disinfection and pharmaceutical oxidation |
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Authors: | Buffle Marc-Olivier Schumacher Jochen Salhi Elisabeth Jekel Martin von Gunten Urs |
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Affiliation: | Department of Water Resources and Drinking Water, Swiss Federal Institute for Environmental Science and Technology (eawag), Switzerland. |
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Abstract: | Due to a lack of adequate experimental techniques, the kinetics of the first 20s of ozone decomposition in natural water and wastewater is still poorly understood. Introducing a continuous quench-flow system (CQFS), measurements starting 350 ms after ozone addition are presented for the first time. Very high HO. to O3 exposures ratios (Rct=integralHO.dt/integralO3dt) reveal that the first 20s of ozonation present oxidation conditions that are similar to ozone-based advanced oxidation processes (AOP). The oxidation of carbamazepine could be accurately modeled using O3 and HO. exposures measured with CQFS during wastewater ozonation. These results demonstrate the applicability of bench scale determined second-order rate constants for wastewater ozonation. Important degrees of pharmaceutical oxidation and microbial inactivation are predicted, indicating that a significant oxidation potential is available during wastewater ozonation, even when ozone is entirely decomposed in the first 20s. |
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Keywords: | Ozone Hydroxyl radicals AOP Ozone demand Quench-flow system Kinetics Disinfection Pharmaceuticals Wastewater Drinking water |
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