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IOA AND IUVA - 3rd Joint WORLD CONGRESS AND EXHIBITION – Las Vegas, NV (2013) O3 AND O3/H2O2 OXIDATION OF PIROXICAM, KETOPROFEN, AND NAPROXEN IN SURFACE WATERS
Ling Feng1, Michael J. Watts2, Daniel Yeh3, Eric van Hul ebusch1 1 Laboratoire Géomatériaux et Environnement, Université Paris-Est, Marne-la-Vallée, France 2 Department of Civil & Environmental Engineering, Florida State University, Tallahassee, FL 3 Department of Civil & Environmental Engineering, University of South Florida, Tampa, FL
Keywords: Ozone, Hydrogen Peroxide, Emerging Contaminants
Objectives. Aqueous ozone is a recognized strong disinfectant, and oxidant of taste and odor
compounds in surface waters. However, in certain waters, further treatment may be required to remove
harmful by-products formed during oxidation. With respect to ozone oxidation of trace xenobiotics, the
goal of treatment is to reduce the contaminant to organic compounds which do not remember the bio-
activity or toxicity of the original molecule. It has been previously demonstrated that these ozone
intermediates from oxidized pollutants are often more bio-degradable than the parent compound and
can be readily removed with biological filtration following ozonation.
The presented work was conducted at Florida State University in 2012, with investigators from Université Paris-Est (France) and the University of South Florida. The goal of the investigation was to observe the kinetics of oxidation for 3 emerging aquatic pollutants of concern (the pharmaceuticals: piroxicam, ketoprofen, and naproxen) under varying ozone treatment regimes, and to both quantitatively and qualitatively assess the pathways for intermediate formation. Finally, bench-scale biological filtration was employed to determine the bio-degradability of chemical intermediates formed in an ozonated surface water. Methodology. Saturated O3 solutions were prepared on the laboratory bench from compressed oxygen
using a plasma arc O3 generator (4 g/hr). Neat standards of the 3 pharmaceuticals were purchased and
dissolved in laboratory-grade water to prepare stock solutions. Aliquots of O3-rich, pH 6 phosphate
buffer were dispensed into solutions of known concentrations of a pharmaceutical. All direct
measurements of pharmaceutical concentration were performed using high-pressure liquid
chromatography with UV detection. Surface water was sampled from a north Florida lake (Lake
Bradford). Before laboratory ozonation, the surface water samples were pre-filtered (0.45 µm) and
diluted with lab-grade water to achieve a DOC of 3 mg/L as C. Media from an operating biologically-
active granular activated carbon filter plant (Tampa, FL) was sampled and shipped overnight to Florida
State University. Loose media was then measured for mass and volume and packed into laboratory
filtration columns for testing. Microbial toxicity in treated samples was measured with the Microtox
Acute Starter Pack (Modern Water, New Castle, DE), according to manufacturer’s specifications.
Results. All 3 target pharmaceuticals were proved labile in ozonated solutions. In dilute buffer solutions
(pH 7), 24%, 60%, and 92% oxidation of piroxicam, ketoprofen, and naproxen was observed with an O3
C∙t of 0.33 mg-min/L. Using competition kinetics, the rate of direct ozone oxidation of piroxicam was
measured on the order of 106 M-1s-1. Maximum inhibition of bacterial luminescence was observed for all
3 oxidized pharmaceutical solutions at O3 C∙t from 0.33 to 0.66 mg-min/L. Results correlating ozone
IOA AND IUVA - 3rd Joint WORLD CONGRESS AND EXHIBITION – Las Vegas, NV (2013) dose, hydrogen peroxide dose, empty-bed contact time for biological GAC filtration, and residual solution toxicity will also be presented. The implications of this study for control of trace xenobiotics and their potentially toxic oxidation intermediates will be discussed in the context of background water quality, careful control of ozone dosing, and the importance of coupling ozonation with biological filtration.

Source: http://worldcongress2013.org/media/docs/abstracts/Abstract_final.pdf

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