Oxidation of 51 micropollutants during drinking water ozonation: Formation of transformation products and their fate during biological post-filtration.

Micropollutants (MP) with varying ozone-reactive moieties were spiked to lake water in the influent of a drinking water pilot plant consisting of an ozonation followed by a biological sand filtration. During ozonation, 227 transformation products (OTPs) from 39 of the spiked 51 MPs were detected after solid phase extraction by liquid chromatography high-resolution mass spectrometry (LC-HRMS/MS). Based on the MS/MS data, tentative molecular structures are proposed.

Oxidant-reactive carbonous moieties in dissolved organic matter: Selective quantification by oxidative titration using chlorine dioxide and ozone.

The application of oxidants for disinfection or micropollutant abatement during drinking water and wastewater treatment is accompanied by oxidation of matrix components such as dissolved organic matter (DOM). To improve predictions of the efficiency of oxidation processes and the formation of oxidation products, methods to determine concentrations of oxidant-reactive phenolic, olefinic or amine-type DOM moieties are critical. Here, a novel selective oxidative titration approach is presented, which is based on reaction kinetics of oxidation reactions towards certain DOM moieties.

Quantification of the electron donating capacity and UV absorbance of dissolved organic matter during ozonation of secondary wastewater effluent by an assay and an automated analyzer.

Ozonation of secondary wastewater treatment plant effluent for the abatement of organic micropollutants requires an accurate process control, which can be based on monitoring ozone-induced changes in dissolved organic matter (DOM). This study presents a novel automated analytical system for monitoring changes in the electron donating capacity (EDC) and UV absorbance of DOM during ozonation. In a first step, a quantitative photometric EDC assay was developed based on electron-transfer reactions from phenolic moieties in DOM to an added chemical oxidant, the radical cation of 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonate) (ABTS).

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

Ozonation of drinking and wastewater relies on ozone (O) and hydroxyl radical (OH) as oxidants. Both oxidants react with dissolved organic matter (DOM) and alter its composition, but the selectivity of the two oxidants and mechanisms of reactivity with DOM moieties are largely unknown. The reactions of O and OH with two DOM isolates were studied by varying specific ozone doses (0.

Chlorothalonil transformation products in drinking water resources: Widespread and challenging to abate.

Chlorothalonil, a fungicide applied for decades worldwide, has recently been banned in the European Union (EU) and Switzerland due to its carcinogenicity and the presence of potentially toxic transformation products (TPs) in groundwater. The spread and concentration range of chlorothalonil TPs in different drinking water resources was examined (73 groundwater and four surface water samples mainly from Switzerland). The chlorothalonil sulfonic acid TPs (R471811, R419492, R417888) occurred more frequently and at higher concentrations (detected in 65-100% of the samples, ≤2200 ngL) than the phenolic TPs (SYN507900, SYN548580, R611968; detected in 10-30% of the samples, ≤130 ngL).

Kinetic and mechanistic aspects of selenite oxidation by chlorine, bromine, monochloramine, ozone, permanganate, and hydrogen peroxide.

Selenium (mainly in the forms of selenite (Se(IV)) and selenate (Se(VI)) is a regulated drinking water contaminant, but there is little information on the kinetics and mechanisms of Se(IV) oxidation during water treatment. Species-specific and apparent second-order rate constants for the oxidation of Se(IV) at pH 7.0 were determined in buffered solutions and they decrease in the order bromine (5.

Two analytical approaches quantifying the electron donating capacities of dissolved organic matter to monitor its oxidation during chlorination and ozonation.

Electron-donating activated aromatic moieties, including phenols, in dissolved organic matter (DOM) partially control its reactivity with the chemical oxidants ozone and chlorine. This comparative study introduces two sensitive analytical systems to directly and selectively quantify the electron-donating capacity (EDC) of DOM, which corresponds to the number of electrons transferred from activated aromatic moieties, including phenols, to the added chemical oxidant 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonate) radical cation (i.e.

Ozone and chlorine reactions with dissolved organic matter - Assessment of oxidant-reactive moieties by optical measurements and the electron donating capacities.

Oxidation processes are impacted by the type, concentration and reactivity of the dissolved organic matter (DOM). In this study, the reactions between various types of DOM (Suwannee River fulvic acid (SRFA), Nordic Reservoir NOM (NNOM) and Pony Lake fulvic acid (PLFA)) and two oxidants (ozone and chlorine) were studied in the pH range 2-9 by using a combination of optical measurements and electron donating capacities. The relationships between residual electron donating capacity (EDC) and residual absorbance showed a strong pH dependence for the ozone-DOM reactions with phenolic functional groups being the main reacting moieties.

Formation of brominated trihalomethanes during chlorination or ozonation of natural organic matter extracts and model compounds in saline water.

Oxidation experiments (chlorine, ozone and bromine) were carried out with synthetic saline waters containing natural organic matter (NOM) extracts and model compounds to evaluate the potential of these surrogates to mimic the formation of brominated trihalomethanes (Br-THMs) in natural saline waters. Synthetic saline water with Pony Lake fulvic acid (PLFA) showed comparable results to natural brackish and sea water for Br-THMs formation during chlorination and ozonation for typical ballast water treatment conditions ([Cl] ≥ 5 mg/L or [O] ≥ 3 mg/L). The molar CHBr yield in synthetic saline waters is higher for chlorination than for ozonation, since ozone reacts slower with bromide and faster with THM precursors.

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.

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 plants (WWTPs). As a consequence, selected WWTPs must be upgraded by an advanced treatment for micropollutant abatement with suitable and economic options such as (powdered) activated carbon treatment or ozonation. WWTP Neugut (105'000 people equivalent) was the first WWTP in Switzerland to implement a long-term full-scale ozonation.

Inactivation of Antibiotic Resistant Bacteria and Resistance Genes by Ozone: From Laboratory Experiments to Full-Scale Wastewater Treatment.

Ozone, a strong oxidant and disinfectant, seems ideal to cope with future challenges of water treatment, such as micropollutants, multiresistant bacteria (MRB) and even intracellular antibiotic resistance genes (ARG), but information on the latter is scarce. In ozonation experiments we simultaneously determined kinetics and dose-dependent inactivation of Escherichia coli and its plasmid-encoded sulfonamide resistance gene sul1 in different water matrixes. Effects in E.

Kinetic and Mechanistic Aspects of the Reactions of Iodide and Hypoiodous Acid with Permanganate: Oxidation and Disproportionation.

Oxidation kinetics of iodide and HOI/OI(-) by permanganate were studied in the pH range of 5.0-10.0.

Reaction of bromine and chlorine with phenolic compounds and natural organic matter extracts--Electrophilic aromatic substitution and oxidation.

Phenolic compounds are known structural moieties of natural organic matter (NOM), and their reactivity is a key parameter for understanding the reactivity of NOM and the disinfection by-product formation during oxidative water treatment. In this study, species-specific and/or apparent second order rate constants and mechanisms for the reactions of bromine and chlorine have been determined for various phenolic compounds (phenol, resorcinol, catechol, hydroquinone, phloroglucinol, bisphenol A, p-hydroxybenzoic acid, gallic acid, hesperetin and tannic acid) and flavone. The reactivity of bromine with phenolic compounds is very high, with apparent second order rate constants at pH 7 in the range of 10(4) to 10(7) M(-1) s(-1).

Combination of UV absorbance and electron donating capacity to assess degradation of micropollutants and formation of bromate during ozonation of wastewater effluents.

In this study, the changes in UV absorbance at 254 nm (UVA254) and electron donating capacity (EDC) were investigated as surrogate indicators for assessing removal of micropollutants and bromate formation during ozonation of wastewater effluents. To measure the EDC, a novel method based on size exclusion chromatography followed by a post-column reaction was developed and calibrated against an existing electrochemical method. Low specific ozone doses led to a more efficient abatement of EDC than of UVA254.

Novel test procedure to evaluate the treatability of wastewater with ozone.

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).

Peracetic acid oxidation of saline waters in the absence and presence of H ₂O ₂: secondary oxidant and disinfection byproduct formation.

Peracetic acid (PAA) is a disinfectant considered for use in ballast water treatment, but its chemical behavior in such systems (i.e., saline waters) is largely unknown.

Chlorination of iodide-containing waters in the presence of CuO: formation of periodate.

It has been shown previously that the disproportionation of halogen-containing oxidants (e.g., HOCl, HOBr, and ClO2) is enhanced by a CuO-catalyzed process.

Chemical oxidation of dissolved organic matter by chlorine dioxide, chlorine, and ozone: effects on its optical and antioxidant properties.

In water treatment dissolved organic matter (DOM) is typically the major sink for chemical oxidants. The resulting changes in DOM, such as its optical properties have been measured to follow the oxidation processes. However, such measurements contain only limited information on the changes in the oxidation states of and the reactive moieties in the DOM.

Prediction of micropollutant elimination during ozonation of municipal wastewater effluents: use of kinetic and water specific information.

Ozonation is effective in improving the quality of municipal wastewater effluents by eliminating organic micropollutants. Nevertheless, ozone process design is still limited by (i) the large number of structurally diverse micropollutants and (ii) the varying quality of wastewater matrices (especially dissolved organic matter). These issues were addressed by grouping 16 micropollutants according to their ozone and hydroxyl radical ((•)OH) rate constants and normalizing the applied ozone dose to the dissolved organic carbon concentration (i.

Iodate and iodo-trihalomethane formation during chlorination of iodide-containing waters: role of bromide.

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 bromide by chlorine significantly enhances the oxidation of iodide to iodate in a bromide-catalyzed process. The pH-dependent kinetics revealed species specific rate constants of k(HOBr + IO(-)) = 1.

Kinetics and mechanisms of N-nitrosodimethylamine formation upon ozonation of N,N-dimethylsulfamide-containing waters: bromide catalysis.

N,N-Dimethylsulfamide (DMS), a newly identified, ubiquitous degradation product of the fungicide tolylfluanide, has been shown to be a N-nitrosodimethylamine (NDMA) precursor during ozonation. In this study, batch ozonation experiments in ultrapure buffered water, surface water, and tap water were performed to determine the kinetics and elucidate the mechanism of NDMA formation from DMS. It was found that at circumneutral pH, DMS reacts slowly with ozone (k approximately 20 M(-1) s(-1)) and moderately with hydroxyl radicals (k=1.

Ozonation of reverse osmosis concentrate: kinetics and efficiency of beta blocker oxidation.

Reverse osmosis (RO) concentrate samples were obtained from a RO-membrane system that uses effluents of wastewater treatment plants (WWTP) as feed water for the production of drinking water. A number of different pharmaceuticals (e.g.

Permeability of low molecular weight organics through nanofiltration membranes.

The removal of natural organic matter (NOM) using nanofiltration (NF) is increasingly becoming an option for drinking water treatment. Low molecular weight (LMW) organic compounds are nevertheless only partially retained by such membranes. Bacterial regrowth and biofilm formation in the drinking water distribution system is favoured by the presence of such compounds, which in this context are considered as the assimilable organic carbon (AOC).

Formation of assimilable organic carbon (AOC) and specific natural organic matter (NOM) fractions during ozonation of phytoplankton.

Ozonation of natural surface water increases the concentration of oxygen-containing low molecular weight compounds. Many of these compounds support microbiological growth and as such are termed assimilable organic carbon (AOC). Phytoplankton can contribute substantially to the organic carbon load when surface water is used as source for drinking water treatment.

Mechanistic and kinetic evaluation of organic disinfection by-product and assimilable organic carbon (AOC) formation during the ozonation of drinking water.

Ozonation of drinking water results in the formation of low molecular weight (LMW) organic by-products. These compounds are easily utilisable by microorganisms and can result in biological instability of the water. In this study, we have combined a novel bioassay for assessment of assimilable organic carbon (AOC) with the detection of selected organic acids, aldehydes and ketones to study organic by-product formation during ozonation.