title: Novel test procedure to evaluate the treatability of wastewater with ozone.
abstract: Organic micropollutants such as pharmaceuticals, estrogens or pesticides enter the environment continuously through the effluent of municipal wastewater treatment plants (WWTPs). Enhanced treatment of wastewater (WW) by ozone (O3) is probably one of the simplest measures for abatement of organic micropollutants to avoid their discharge to the aquatic environment. During ozonation most organic micropollutants present in treated WW are oxidized either by a direct reaction with O3 or by secondarily formed hydroxyl radicals (OH). However, undesired oxidation by-products from the oxidative transformation of matrix components can also be formed. A modular laboratory decision tool based on the findings of previous investigations is presented to test the feasibility of ozonation as an option to upgrade specific WWTPs. These modules consist of investigations to assess (i) the matrix effects on ozone stability, (ii) the efficiency of micropollutant removal, (iii) the oxidation by-product formation, as well as (iv) bioassays to measure specific and unspecific toxicity of the treated WWs. Matrix effects on ozone stability (quantified as O3 and OH exposures) can give first indications on the suitability of an ozonation step. Ozonation of WWs yielding O3 and OH exposures and micropollutant abatement similar to reference values evoked a significant improvement of the water quality as indicated by a broad range of bioassays. Irregular behavior of the ozonation points towards unknown compounds, possibly leading to the formation of undesired degradation products. It has been observed that in such WWs ozonation partly enhanced toxicity. In summary, the presented tiered laboratory test procedure represents a relatively cheap and straight-forward methodology to evaluate the feasibility of ozonation to upgrade specific WWTPs for micropollutant removal based on chemical and biological measurements.
authors.affiliation: Eawag, Swiss Federal Institute of Aquatic Science and Technology, P.O. Box 611, 8600 Dübendorf, Switzerland; Federal Office for the Environment (FOEN), Water Division, 3003 Bern, Switzerland. Electronic address: yael.schindler@eawag.ch.
authors.forename: Yael
authors.initials: Y
authors.lastname: Schindler Wildhaber
authors.affiliation: Eawag, Swiss Federal Institute of Aquatic Science and Technology, P.O. Box 611, 8600 Dübendorf, Switzerland. Electronic address: hana.mestankova@eawag.ch.
authors.forename: Hana
authors.initials: H
authors.lastname: Mestankova
authors.affiliation: Federal Office for the Environment (FOEN), Water Division, 3003 Bern, Switzerland. Electronic address: michael.schaerer@bafu.admin.ch.
authors.forename: Michael
authors.initials: M
authors.lastname: Schärer
authors.affiliation: Eawag, Swiss Federal Institute of Aquatic Science and Technology, P.O. Box 611, 8600 Dübendorf, Switzerland; School of Architecture, Civil and Environmental Engineering (ENAC), Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland; Institute of Biogeochemistry and Pollutant Dynamics, ETH Zurich, 8092 Zürich, Switzerland. Electronic address: kristin.schirmer@eawag.ch.
authors.forename: Kristin
authors.initials: K
authors.lastname: Schirmer
authors.affiliation: Eawag, Swiss Federal Institute of Aquatic Science and Technology, P.O. Box 611, 8600 Dübendorf, Switzerland. Electronic address: elisabeth.salhi@eawag.ch.
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Salhi
authors.affiliation: Eawag, Swiss Federal Institute of Aquatic Science and Technology, P.O. Box 611, 8600 Dübendorf, Switzerland; School of Architecture, Civil and Environmental Engineering (ENAC), Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland; Institute of Biogeochemistry and Pollutant Dynamics, ETH Zurich, 8092 Zürich, Switzerland. Electronic address: vongunten@eawag.ch.
authors.forename: Urs
authors.initials: U
authors.lastname: von Gunten
mesh_terms: D010126:Ozone / Q000737:chemistry*; D018675:Toxicity Tests; D014865:Waste Disposal, Fluid / Q000379:methods*; D062065:Wastewater / Q000032:analysis*; D014874:Water Pollutants, Chemical / Q000737:chemistry*; D060753:Water Quality
chemical_list: D010126:Ozone; D062065:Wastewater; D014874:Water Pollutants, Chemical
keywords: Bioassays; Effluent toxicity; Micropollutant oxidation; Oxidation by-products; Ozonation; Transformation products