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Urs von Gunten

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Related publications (155)

Page 4 of 8

Comparison of the impact of ozone, chlorine dioxide, ferrate and permanganate pre-oxidation on organic disinfection byproduct formation during post-chlorination

Urs von Gunten

Pre-oxidation is commonly used to mitigate the formation of byproducts during post-disinfection. A comparative study of the impact of four pre-oxidants, ozone (O-3), chlorine dioxide (ClO2), permanganate (Mn(vii)) and ferrate (Fe(vi)), on the formation of ...

ROYAL SOC CHEMISTRY2020

Molecular-Level Transformation of Dissolved Organic Matter during Oxidation by Ozone and Hydroxyl Radical

Urs von Gunten

Ozonation of drinking and wastewater relies on ozone (O-3) and hydroxyl radical ((OH)-O-center dot) as oxidants. Both oxidants react with dissolved organic matter (DOM) and alter its composition, but the selectivity of the two oxidants and mechanisms of re ...

AMER CHEMICAL SOC2020

Micropollutant Oxidation Studied by Quantum Chemical Computations: Methodology and Applications to Thermodynamics, Kinetics, and Reaction Mechanisms

Urs von Gunten, Peter Rudolf Tentscher, Minju Lee

The abatement of organic micropollutants during oxidation processes has become an emerging issue for various urban water systems such as drinking water, wastewater, and water reuse. Reaction kinetics and mechanisms play an important role in terms of effici ...

American Chemical Society2019

Oxidation of cetirizine, fexofenadine and hydrochlorothiazide during ozonation: Kinetics and formation of transformation products

Urs von Gunten

The efficiency of wastewater ozonation for the abatement of three nitrogen-containing pharmaceuticals, two antihistamine drugs, cetirizine (CTR) and fexofenadine (FXF), and the diuretic drug, hydrochlorothiazide (HCTZ), was investigated. Species-specific s ...

Elsevier2016

Iodate and Iodo-Trihalomethane Formation during Chlorination of Iodide-Containing Waters: Role of Bromide

Urs von Gunten

The kinetics of iodate formation is a critical factor in mitigation of the formation of potentially toxic and off flavor causing iodoorganic compounds during chlorination. This study demonstrates that the formation of bromine through the oxidation of bromi ...

2012

Fingerprinting the reactive toxicity pathways of 50 drinking water disinfection by-products

Urs von Gunten

A set of nine in vitro cellular bioassays indicative of different stages of the cellular toxicity pathway was applied to 50 disinfection by-products (DBPs) to obtain a better understanding of the commonalities and differences in the molecular mechanisms of ...

Elsevier2016

Mechanistic Study on the Formation of Cl-/Br-/I-Trihalomethanes during Chlorination/Chloramination Combined with a Theoretical Cytotoxicity Evaluation

Urs von Gunten

Chlorination followed by chloramination can be used to mitigate the formation of potentially toxic iodinated disinfection byproducts (I-DBPs) while controlling the formation of regulated chloro-bromo-DBPs (Cl-/Br-DBPs). Water samples containing dissolved o ...

American Chemical Society2015

Evaluation of a full-scale wastewater treatment plant upgraded with ozonation and biological post-treatments: Abatement of micropollutants, formation of transformation products and oxidation by-products

Urs von Gunten

To protect the ecosystem and drinking water resources in Switzerland and in the countries of the downstream catchments, a new Swiss water protection act entered into force in 2016 aiming to reduce the discharge of micropollutants from wastewater treatment ...

2018

Reactivity of Bromine Radical with Dissolved Organic Matter Moieties and Monochloramine: Effect on Bromate Formation during Ozonation

Urs von Gunten, Sung Eun Lim

Bromine radical (Br center dot) has been hypothesized to be a key intermediate of bromate formation during ozonation. Once formed, Br center dot further reacts with ozone to eventually form bromate. However, this reaction competes with the reaction of Br c ...

AMER CHEMICAL SOC2023

Proxies to monitor the inactivation of viruses by ozone in surface water and wastewater effluent

Urs von Gunten, Tamar Kohn, Camille Wolf

Ozone treatment is an effective barrier against viral pathogens, therefore it is an integral part of many water and wastewater treatment trains. However, the efficacy of ozone treatment remains difficult to monitor, due to the lack of methods to track viru ...

2019

Determinants of disinfectant pretreatment efficacy for nitrosamine control in chloraminated drinking water

Urs von Gunten

Utilities using chloramines need strategies to mitigate nitrosamine formation to meet potential future nitrosamine regulations. The ability to reduce NDMA formation under typical post-chloramination conditions of pretreatment with ultraviolet light from a ...

Elsevier2015

Ozonation of organic compounds in water and wastewater: A critical review

Urs von Gunten, Sung Eun Lim

Ozonation has been applied in water treatment for more than a century, first for disinfection, later for oxidation of inorganic and organic pollutants. In recent years, ozone has been increasingly applied for enhanced municipal wastewater treatment for eco ...

PERGAMON-ELSEVIER SCIENCE LTD2022

Fate of Cr(III) during ozonation of secondary municipal wastewater effluent

Urs von Gunten, Caroline Gachet Aquillon

In the present study, the fate of trivalent chromium (Cr(III)) during ozonation of ultrapurified water and wastewater effluent was investigated. In experiments conducted in phosphate buffered ultrapurified water, O3 alone in excess was inefficient to oxidi ...

2018

Reactivity of Cyanobacteria Metabolites with Ozone: Multicompound Competition Kinetics

Urs von Gunten

Cyanobacterial blooms occur at increasing frequency and intensity, notably in freshwater. This leads to the introduction of complex mixtures of their products, i.e., cyano-metabolites, to drinking water treatment plants. To assess the fate of cyano-metabol ...

Amer Chemical Soc2024

Effect of Dissolved Organic Matter on the Transformation of Contaminants Induced by Excited Triplet States and the Hydroxyl Radical

Urs von Gunten

Dissolved organic matter (DOM) has recently been shown to reduce the transformation rate of various aqueous organic contaminants submitted to oxidation by excited triplet states, apparently by inhibiting the transformation of oxidation intermediates. The m ...

2011

Oxidative treatment of bromide-containing waters: Formation of bromine and its reactions with inorganic and organic compounds - A critical review

Urs von Gunten, Michèle Bernadette Heeb, Saskia Gisela Zimmermann-Steffens

Bromide (Br-) is present in all water sources at concentrations ranging from similar to 10 to >1000 mu g L-1 in fresh waters and about 67 mg L-1 in seawater. During oxidative water treatment bromide is oxidized to hypobromous acid/hypobromite (HOBr/OBr-) a ...

Elsevier2014

Impact of Combined Chlorination and Chloramination Conditions on N-Nitrosodimethylamine Formation

Urs von Gunten

Bench-scale chloramination under uniform formation conditions was used to examine N-nitrosodimethylamine (NDMA) formation in settled and (bio)filtered drinking water and treated wastewater. In this study, water temperature, pH, postchloramination time, and ...

WILEY2018

Aqueous Equilibrium Constants Of Formation For Bromamines, Chloramines, And Bromochloramines: Quantum Chemistry Estimates

Urs von Gunten, Jeremy Samuel Arey, Daniela Trogolo

Royal Soc Chemistry2016

Nitrate formation during ozonation as a surrogate parameter for abatement of micropollutants and the N-nitrosodimethylamine (NDMA) formation potential

Urs von Gunten, Florian Frédéric Vincent Breider, Jun Ma

In this study, nitrate formation from ammonium and/or dissolved organic nitrogen (DON) was investigated as a novel surrogate parameter to evaluate the abatement of micropollutants during ozonation of synthetic waters containing natural organic matter (NOM) ...

Elsevier2017

Iodide sources in the aquatic environment and its fate during oxidative water treatment - A critical review

Urs von Gunten

Iodine is a naturally-occurring halogen in natural waters generally present in concentrations between 0.5 and 100 mu g L-1. During oxidative drinking water treatment, iodine-containing disinfection by-products (I-DBPs) can be formed. The formation of I-DBP ...

PERGAMON-ELSEVIER SCIENCE LTD2022