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      Advances in predicting organic contaminant abatement during ozonation of municipal wastewater effluent: reaction kinetics, transformation products, and changes of biological effects

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          Abstract

          Ozonation of municipal wastewater effluent has been considered in recent years as an enhanced wastewater treatment technology to abate trace organic contaminants (micropollutants).

          Abstract

          Ozonation of municipal wastewater effluent has been considered in recent years as an enhanced wastewater treatment technology to abate trace organic contaminants (micropollutants). The efficiency of ozonation for micropollutant abatement depends on (1) the reactivity of ozone and OH radical (˙OH) with the target micropollutant, (2) the dosage of ozone and the stability of ozone and ˙OH in a given water matrix, (3) the removal of undesirable effects ( e.g., biological activities) of a micropollutant after structural transformation, and (4) the biodegradability of transformation products in biological post-treatment. In this article, recent advances in predicting organic micropollutant abatement during ozonation of municipal wastewater effluents are reviewed with a focus on (i) principle-based approaches for describing and modeling the reaction kinetics of ozone and ˙OH, (ii) transformation products and pathways, (iii) changes of biological activities, and (iv) biodegradation of transformation products in biological post-treatment. Using the chemical kinetics based on ozone and ˙OH rate constants ( i.e., compound-specific information) and exposures ( i.e., water matrix-specific information), a generalized prediction of the abatement efficiency of various micropollutants in varying water quality appears to be possible. QSAR-type correlations based on Hammett coefficients or quantum chemical energy calculations or (semi)empirical models have been developed for predicting the ozone and ˙OH rate constants and exposures, respectively. Models based on the ozone and ˙OH reaction rules can be used to predict the transformation products of micropollutants by ozone and ˙OH. Reaction rule-based models in combination with the chemical kinetics information will enable the prediction of transformation product evolution during ozonation. The biological activities of transformation products have been assessed by an effect-driven approach using in vitro bioassays. Biological activities with specific modes of action ( e.g., receptor-binding activities) were found to be quite efficiently removed, upon slight structural modifications by ozone or ˙OH. The formation of new biological activities has also been observed, which warrants identification of the responsible toxicophore(s) and quantitative exposure-based risk assessment. Finally, there is only limited experimental information on the biodegradability of transformation products; however, biodegradability probability models can be used to make first estimates. In future research, the discussed principle-based approaches can be more actively applied to determine and predict not only the abatement levels of the parent micropollutants but also the formation of transformation products and the consequent changes of biological activities and biodegradability, which determines the overall treatment efficiency.

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          Most cited references149

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          Critical Review of rate constants for reactions of hydrated electronsChemical Kinetic Data Base for Combustion Chemistry. Part 3: Propane

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            Collapse of a fish population after exposure to a synthetic estrogen.

            Municipal wastewaters are a complex mixture containing estrogens and estrogen mimics that are known to affect the reproductive health of wild fishes. Male fishes downstream of some wastewater outfalls produce vitellogenin (VTG) (a protein normally synthesized by females during oocyte maturation) and early-stage eggs in their testes, and this feminization has been attributed to the presence of estrogenic substances such as natural estrogens [estrone or 17beta-estradiol (E2)], the synthetic estrogen used in birth-control pills [17 alpha-ethynylestradiol (EE2)], or weaker estrogen mimics such as nonylphenol in the water. Despite widespread evidence that male fishes are being feminized, it is not known whether these low-level, chronic exposures adversely impact the sustainability of wild populations. We conducted a 7-year, whole-lake experiment at the Experimental Lakes Area (ELA) in northwestern Ontario, Canada, and showed that chronic exposure of fathead minnow (Pimephales promelas) to low concentrations (5-6 ng x L(-1)) of the potent 17 alpha-ethynylestradiol led to feminization of males through the production of vitellogenin mRNA and protein, impacts on gonadal development as evidenced by intersex in males and altered oogenesis in females, and, ultimately, a near extinction of this species from the lake. Our observations demonstrate that the concentrations of estrogens and their mimics observed in freshwaters can impact the sustainability of wild fish populations.
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              Ozonation of drinking water: part I. Oxidation kinetics and product formation.

              The oxidation of organic and inorganic compounds during ozonation can occur via ozone or OH radicals or a combination thereof. The oxidation pathway is determined by the ratio of ozone and OH radical concentrations and the corresponding kinetics. A huge database with several hundred rate constants for ozone and a few thousand rate constants for OH radicals is available. Ozone is an electrophile with a high selectivity. The second-order rate constants for oxidation by ozone vary over 10 orders of magnitude, between < 0.1 M(-1)s(-1) and about 7 x 10(9) M(-1)s(-1). The reactions of ozone with drinking-water relevant inorganic compounds are typically fast and occur by an oxygen atom transfer reaction. Organic micropollutants are oxidized with ozone selectively. Ozone reacts mainly with double bonds, activated aromatic systems and non-protonated amines. In general, electron-donating groups enhance the oxidation by ozone whereas electron-withdrawing groups reduce the reaction rates. Furthermore, the kinetics of direct ozone reactions depend strongly on the speciation (acid-base, metal complexation). The reaction of OH radicals with the majority of inorganic and organic compounds is nearly diffusion-controlled. The degree of oxidation by ozone and OH radicals is given by the corresponding kinetics. Product formation from the ozonation of organic micropollutants in aqueous systems has only been established for a few compounds. It is discussed for olefines, amines and aromatic compounds. Copyright 2002 Elsevier Science Ltd.
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                Author and article information

                Journal
                ESWRAR
                Environmental Science: Water Research & Technology
                Environ. Sci.: Water Res. Technol.
                Royal Society of Chemistry (RSC)
                2053-1400
                2053-1419
                2016
                2016
                : 2
                : 3
                : 421-442
                Affiliations
                [1 ]School of Environmental Science and Engineering
                [2 ]Gwangju Institute of Science and Technology (GIST)
                [3 ]Gwangju 500-712
                [4 ]Republic of Korea
                [5 ]School of Architecture, Civil, and Environmental Engineering (ENAC)
                [6 ]École Polytechnique Fédérale de Lausanne
                [7 ]Lausanne
                [8 ]Switzerland
                [9 ]Eawag
                Article
                10.1039/C6EW00025H
                5535f0c8-7519-48b9-a437-6ada3a180d0c
                © 2016
                History

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