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Mechnanistischer Ansatz zur Identifizierung von Quellen von Mutagenität, welche während der Ozonung von Abwasser gebildet wird

English title A mechanistic approach for identifying sources of mutagenicity formed during wastewater ozonation
Applicant von Gunten Urs
Number 157143
Funding scheme Project funding
Research institution Swiss Federal Institute of Aquatic Science and Technology (EAWAG)
Institution of higher education Swiss Federal Institute of Aquatic Science and Technology - EAWAG
Main discipline Other disciplines of Environmental Sciences
Start/End 01.05.2015 - 30.06.2017
Approved amount 283'544.00
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All Disciplines (2)

Discipline
Other disciplines of Environmental Sciences
Other disciplines of Engineering Sciences

Keywords (7)

Water treatment; Mutagenicity; Modeling; Micropollutants; Mechanisms; Ozonation; Transformation products

Lay Summary (German)

Lead
In der Schweiz wurden Massnahmen beschlossen, um die Emission von organischen Spurenstoffen aus Kläranlagen in die Vorfluter zu vermindern. Dazu ist geplant ca. 100 von 700 Kläranlagen mit einer weiteren Stufe zur weitergehenden Abwasserreinigung aufzurüsten, um die Fracht an Spurenstoffen in die Gewässer um 50% zu reduzieren. Dazu stehen heute zwei Technologien, eine Ozonung oder der Einsatz von Pulveraktivkohle zur Verfügung. Im vorliegenden Projekt wird die Ozonung bezüglich Bildung von potentiell toxischen Abbauprodukten der Edukte von Spurenstoffen untersucht. Dazu werden sowohl experimentelle als auch in silico Methoden verwendet, um eine möglichst breite Auswahl von Spurenstoffen zu beurteilen.
Lay summary

Die Ozonung ist eine Technologie, die zur geplanten weitergehenden Abwasserreinigung zur Entfernung von Spurenstoffen zur verfügen steht. Es konnte in zahlreichen Studien gezeigt werden, dass Ozon viele Spurenstoffe, wie z. B., hormonaktive Substanzen, Arzneimittel und Kosmetika, die im Ablauf von Kläranlagen gefunden werden, effizient oxidieren kann. Allerdings werden diese Stoffe für typischer Ozondosen nicht mineralisiert, sondern es werden Transformationsprodukte gebildet, welche mehr oder weniger ähnliche Strukturen wie die Edukte haben. Für viele Zielsubstanzen konnte eine vollständige Elimination der ursprünglichen Effekte nachgewiesen werden, obwohl die Strukturen dieser Verbindungen z. T. nur geringfügig verändert wurden. Ähnliche Resultate mit einer geringeren biologischen Aktivität der behandelten Proben, wurden auch bei der Ozonung von Kläranlagenabläufen erzielt. Trotz diesen positiven Effekten der Ozonung, wurde in einzelnen Fällen beobachtet, dass behandelte Proben eine höhere biologische Aktivität aufwiesen. Ein Endpunkt, der bei der Ozonug verschiedener Spurenstoffe beobachtet wurde und der zu Sorge Anlass gibt, ist die Mutagenität, d.h., Schädigung der DNA mit möglichen Langzeitfolgen, wie der Ausbildung von Krebs.  Es ist im Moment schwierig diese Befunde bei Einzelsubstanzen einzustufen und es gibt keine Möglichkeit alle Substanzen zu testen oder die Bildungspotentiale für mutagene Substanzen abzuschätzen. Basierend auf einem Modell zur Vorhersage von Ozonungsprodukten, welches gegenwärtig in Bearbeitung ist, werden wir im vorliegenden Projekt eine Methode zum automatischen Screening von Edukten auf ihr Potential zur Bildung von mutagenen Substanzen entwicklen. Bei einem positiven Befund aus dem Modell wird die Mutagenität in vitro getestet und bei einer experimentellen Bestätigung des Modells werden die verantwortlichen Produkte isoliert. So können kritische Substanzen identifiziert und mögliche Massnahmen an der Quelle ergriffen werden.

Direct link to Lay Summary Last update: 05.02.2015

Responsible applicant and co-applicants

Employees

Publications

Publication
Gas-Phase Ozone Reactions with a Structurally Diverse Set of Molecules: Barrier Heights and Reaction Energies Evaluated by Coupled Cluster and Density Functional Theory Calculations
Trogolo Daniela, Arey J. Samuel, Tentscher Peter R. (2018), Gas-Phase Ozone Reactions with a Structurally Diverse Set of Molecules: Barrier Heights and Reaction Energies Evaluated by Coupled Cluster and Density Functional Theory Calculations, in The Journal of Physical Chemistry A, 123(2), 517-536.
Ozonation of Para -Substituted Phenolic Compounds Yields p -Benzoquinones, Other Cyclic α,β-Unsaturated Ketones, and Substituted Catechols
Tentscher Peter R., Bourgin Marc, von Gunten Urs (2018), Ozonation of Para -Substituted Phenolic Compounds Yields p -Benzoquinones, Other Cyclic α,β-Unsaturated Ketones, and Substituted Catechols, in Environmental Science & Technology, 52(8), 4763-4773.

Collaboration

Group / person Country
Types of collaboration
Prof. Beate Escher, UFZ Leipzig Germany (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Research Infrastructure

Scientific events

Active participation

Title Type of contribution Title of article or contribution Date Place Persons involved
ACS Spring Meeting 2017 Talk given at a conference Ozonation of substituted phenolic model compounds: Yields and toxicology of p-benzoquinones and polyphenols 02.04.2017 San Francisco, United States of America Bramaz Nadine; Tentscher Peter; von Gunten Urs; Schirmer Kristin;
ACS Spring Meeting 2017 Poster QSAR prediction of rate constants for the reaction of ozone with organic compounds using quantum chemical descriptors beyond HOMO 02.04.2017 San Franciso, United States of America Tentscher Peter; von Gunten Urs;


Awards

Title Year
ACS Editor's Choice des Artikels "Tentscher, P. R., M. Bourgin and U. von Gunten (2018). "Ozonation of Para-Substituted Phenolic Compounds Yields p-Benzoquinones, Other Cyclic α,β-Unsaturated Ketones, and Substituted Catechols." Environmental Science & Technology 52(8): 4763-4773." Erschienen in ES&T am 17. April, 2018 inklusive Titelbild. 2018

Associated projects

Number Title Start Funding scheme
162331 Oxidation of Cr(III) during ozonation of municipal wastewater 01.07.2015 International short research visits
149711 Next-generation environmental biotransformation pathway prediction system - NGE-PPS 01.04.2014 Interdisciplinary projects
181975 Reactions of ozone with water matrix components: reactive sites and oxidation by-product formation 01.11.2018 Project funding

Abstract

Ozonation is one of the two options considered for the planned upgrade of Swiss wastewater treatment plants, aiming at the removal of micropollutants. Ozone has been shown to be effective for the elimination of micropollutants such as endocrine disruptors, pharmaceuticals and personal care products, which can be found in wastewater effluents. However, for typical ozonation processes in water treatment, mineralization of these compounds cannot be achieved. Rather, transformation products with more or less structural similarities to the parent compound are formed. A complete abatement of the intended biological effects has been observed for e.g., estrogenic compounds, antibiotics, antiviral compounds and herbicides, upon sometimes minor changes in the structure of the parent compound. This has been demonstrated for individual compounds, and similar trends have also been observed for whole wastewater effluents, for which lower levels of specific biological activities were measured after ozonation. Despite these positive effects of ozonation, it was found in certain cases that transformation products exerted increased biological activity with potential negative consequences for exposed organisms. One of the activities of main concern is mutagenicity, i.e. damage to DNA with suspected long-term consequences, such as cancer. Mutagenicity has been detected in mixtures of ozone transformation products of several parent compounds, and in oxidized wastewater effluents. Owing to the large number of micropollutants present in wastewater effluents, it is impossible to test each compound individually for development of mutagenicity; a high throughput pre-screening approach is necessary to reduce the experimental effort. Based on a prediction tool for ozone transformation reactions (O3-PPS), which is currently being developed in our group, we will implement an automatic screening for mutagenicity to identify parent compounds that may lead to mutagenic products upon ozonation. In case of a positive alert from the model, we will measure mutagenicity of the ozonation reaction mixtures resulting from ozonation of the respective parent compounds, and elucidate the transformation products leading to this effect. Furthermore, we aim at studying parent compounds which might yield mutagenic ozonation products that have not yet been reported before: epoxides, a-chlorinated aldehydes, and quinones. We hypothesize that these compounds have been overlooked because they may form as side reactions in small concentrations only. Finally, we will investigate the formation of mutagenic compounds from model compounds representative of structures of dissolved organic matter (DOM) and selected well-characterized natural organic matter. The main objectives of the project are:1.To test of the robustness of O3-PPS to correctly treat a large variety of complex molecules. 2.To identify reaction pathways which lead to mutagenic epoxides, a-chlorinated aldehydes and quinones and to include these pathways in the O3-PPS.3.To develop an automated in silico pre-screening workflow, based on transformation product prediction (O3-PPS) and structure-based prediction of the mutagenicity of these transformation products.4.Application of this in silico pre-screening workflow to the ozonation of common wastewater pollutants, followed by in vitro screening for mutagenicity of prioritized pollutants.5.Experimental confirmation of the identity of mutagenic transformation products. 6.In vitro assessment of mutagenic ozonation byproducts of the wastewater matrix DOM and DOM model compounds.
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