Staff

Christa McArdell

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Dr. Christa McArdell

Senior scientist / group leader

Department Environmental Chemistry

About Me

RESEARCH INTERESTS

Input and fate of organic contaminants from different urban sources, including hospitals and industries, in the aquatic environment.

Wastewater treatment processes and strategies for the removal of organic micropollutants in conventional and advanced treatment with ozone and activated carbon; formation and fate of ozonation transformation products.

Development of analytical techniques for the determination of organic pollutants and (ozonation) transformation products with LC-(HR)MS/MS in sewage and ambient waters.

PROJECT OVERVIEW

See my research project page

Curriculum Vitae

1996-present Eawag, Department of Environmental Chemistry, Duebendorf, Group Leader.
2021-present Teaching at ETH Zurich, Department of Chemistry and Applied Biosciences as lecturer.
1997-2001 Teaching at ETH Zurich, Department of Civil, Environmental and Geomatic Engineering (2000-2001) as laboratory course lecturer; at Department of Environmental Sciences (1997-2000) as lecturer and laboratory course coordinator.
2001-2005 Eawag, Duebendorf, and Swiss National Science Foundation (SNF), Bern, Assistant for the evaluation of SNF proposals.
1994-1996 The Johns Hopkins University, Department of Geography and Environmental Engineering, Baltimore, USA, Postdoctoral researcher.
1990-1994 ETH Zurich, Institute of Terrestrial Ecology, Switzerland, PhD student (PhD Sc. Nat.)
1992 ETH Zurich, Dept. of Social Sciences and Humanities and Dept. of Chemistry,  “Höheres Lehramt” (teaching certificate in Chemistry).
1985-1990 ETH Zurich, Dept. of Chemistry, Diploma studies in Chemistry.

Links to publications

researcherID      ORCID      researchgate     institutional repository

Publications

GAK-Filter für die Spurenstoffentfernung. Erfahrungen und Betriebsergebnisse der Pilotstudien ARA Furt/Bülach und Glarnerland

Auf den Kläranlagen Furt/Bülach und Glarnerland des Abwasserverbandes Glarnerland (AVG, Bilten) wurden zwischen 2014 und 2019 umfangreiche Untersuchungen zur Elimination von Mikroverunreinigungen mittels granulierter Aktivkohle (GAK) durchgeführt. Ziel war es, unter Schweizer Praxisbedingungen die Machbarkeit, Effizienz und Wirtschaftlichkeit des Verfahrens zu evaluieren. Fazit beider Forschungsprojekte ist, dass sich die GAK-Filtration zur Spurenstoffelimination gemäss Schweizer Gesetzgebung eignet. Das Verfahren ist technisch und wirtschaftlich realisierbar und hat sich als praxistauglich erwiesen.
Böhler, M. A.; Joss, A.; McArdell, C. S. (2022) GAK-Filter für die Spurenstoffentfernung. Erfahrungen und Betriebsergebnisse der Pilotstudien ARA Furt/Bülach und Glarnerland, Aqua & Gas, 102(1), 48-54, Institutional Repository

Evaluation of a full-scale wastewater treatment plant with ozonation and different post-treatments using a broad range of in vitro and in vivo bioassays

Micropollutants present in the effluent of wastewater treatment plants (WWTPs) after biological treatment are largely eliminated by effective advanced technologies such as ozonation. Discharge of contaminants into freshwater ecosystems can thus be minimized, while simultaneously protecting drinking water resources. However, ozonation can lead to reactive and potentially toxic transformation products. To remove these, the Swiss Federal Office for the Environment recommends additional "post-treatment" of ozonated WWTP effluent using sand filtration, but other treatments may be similarly effective. In this study, 48 h composite wastewater samples were collected before and after full-scale ozonation, and after post-treatments (full-scale sand filtration, pilot-scale fresh and pre-loaded granular activated carbon, and fixed and moving beds). Ecotoxicological tests were performed to quantify the changes in water quality following different treatment steps. These included standard in vitro bioassays for the detection of endocrine, genotoxic and mutagenic effects, as well as toxicity to green algae and bacteria, and flow-through in vivo bioassays using oligochaetes and early life stages of rainbow trout.
Results show that ozonation reduced a number of ecotoxicological effects of biologically treated wastewater by 66 - 93%: It improved growth and photosynthesis of green algae, decreased toxicity to luminescent bacteria, reduced concentrations of hormonally active contaminants and significantly changed expression of biomarker genes in rainbow trout liver. Bioassay results showed that ozonation did not produce problematic levels of reaction products overall. Small increases in toxicity observed in a few samples were reduced or eliminated by post-treatments. However, only relatively fresh granular activated carbon (analyzed at 13,000 - 20,000 bed volumes) significantly reduced effects additionally (by up to 66%) compared to ozonation alone. Inhibition of algal photosynthesis, rainbow trout liver histopathology and biomarker gene expression proved to be sufficiently sensitive endpoints to detect the change in water quality achieved by post-treatment.
Kienle, C.; Werner, I.; Fischer, S.; Lüthi, C.; Schifferli, A.; Besselink, H.; Langer, M.; McArdell, C. S.; Vermeirssen, E. L. M. (2022) Evaluation of a full-scale wastewater treatment plant with ozonation and different post-treatments using a broad range of in vitro and in vivo bioassays, Water Research, 212, 118084 (13 pp.), doi:10.1016/j.watres.2022.118084, Institutional Repository

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. Reaction mechanisms for the formation of a large number of OTPs are suggested by combination of the kinetics of formation and abatement and state-of-the-art knowledge on ozone and hydroxyl radical chemistry. OTPs forming as primary or higher generation products from the oxidation of MPs could be differentiated. However, some expected products from the reactions of ozone with activated aromatic compounds and olefins were not detected with the applied analytical procedure. 187 OTPs were present in the sand filtration in sufficiently high concentrations to elucidate their fate in this treatment step. 35 of these OTPs (19%) were abated in the sand filtration step, most likely due to biodegradation. Only 24 (13%) of the OTPs were abated more efficiently than the parent compounds, with a dependency on the functional group of the parent MPs and OTPs. Overall, this study provides evidence, that the common assumption that OTPs are easily abated in biological post-treatment is not generally valid. Nevertheless, it is unknown how the OTPs, which escaped detection, would have behaved in the biological post-treatment.
Gulde, R.; Clerc, B.; Rutsch, M.; Helbing, J.; Salhi, E.; McArdell, C. S.; von Gunten, U. (2021) Oxidation of 51 micropollutants during drinking water ozonation: formation of transformation products and their fate during biological post-filtration, Water Research, 207, 117812 (20 pp.), doi:10.1016/j.watres.2021.117812, Institutional Repository

Formation of transformation products during ozonation of secondary wastewater effluent and their fate in post-treatment: from laboratory- to full-scale

Ozonation is increasingly applied in water and wastewater treatment for the abatement of micropollutants (MPs). However, the transformation products formed during ozonation (OTPs) and their fate in biological or sorptive post-treatments is largely unknown. In this project, a high-throughput approach, combining laboratory ozonation experiments and detection by liquid chromatography high-resolution mass spectrometry (LC-HR-MS/MS), was developed and applied to identify OTPs formed during ozonation of wastewater effluent for a large number of relevant MPs (total 87). For the laboratory ozonation experiments, a simplified experimental solution, consisting of surrogate organic matter (methanol and acetate), was created, which produced ozonation conditions similar to realistic conditions in terms of ozone and hydroxyl radical exposures. The 87 selected parent MPs were divided into 19 mixtures, which enabled the identification of OTPs with an optimized number of experiments. The following two approaches were considered to identify OTPs. (1) A screening of LC-HR-MS signal formation in these experiments was performed and revealed a list of 1749 potential OTP candidate signals associated to 70 parent MPs. This list can be used in future suspect screening studies. (2) A screening was performed for signals that were formed in both batch experiments and in samples of wastewater treatment plants (WWTPs). This second approach was ultimately more time-efficient and was applied to four different WWTPs with ozonation (specific ozone doses in the range 0.23-0.55 gO3/gDOC), leading to the identification of 84 relevant OTPs of 40 parent MPs in wastewater effluent. Chemical structures could be proposed for 83 OTPs through the interpretation of MS/MS spectra and expert knowledge in ozone chemistry. Forty-eight OTPs (58%) have not been reported previously. The fate of the verified OTPs was studied in different post-treatment steps. During sand filtration, 87-89% of the OTPs were stable. In granular activated carbon (GAC) filters, OTPs were abated with decreasing efficiency with increasing run times of the filters. For example, in a GAC filter with 16,000 bed volumes, 53% of the OTPs were abated, while in a GAC filter with 35,000 bed volumes, 40% of the OTPs were abated. The highest abatement (87% of OTPs) was observed when 13 mg/L powdered activated carbon (PAC) was dosed onto a sand filter.
Gulde, R.; Rutsch, M.; Clerc, B.; Schollée, J. E.; von Gunten, U.; McArdell, C. S. (2021) Formation of transformation products during ozonation of secondary wastewater effluent and their fate in post-treatment: from laboratory- to full-scale, Water Research, 200, 117200 (16 pp.), doi:10.1016/j.watres.2021.117200, Institutional Repository

Characterization of advanced wastewater treatment with ozone and activated carbon using LC-HRMS based non-target screening with automated trend assignment

Advanced treatment is increasingly being applied to improve abatement of micropollutants in wastewater effluent and reduce their load to surface waters. In this study, non-target screening of high-resolution mass spectrometry (HRMS) data, collected at three Swiss wastewater treatment plants (WWTPs), was used to evaluate different advanced wastewater treatment setups, including (1) granular activated carbon (GAC) filtration alone, (2) pre-ozonation followed by GAC filtration, and (3) pre-ozonation followed by powdered activated carbon (PAC) dosed onto a sand filter. Samples were collected at each treatment step of the WWTP and analyzed with reverse-phase liquid chromatography coupled to HRMS. Each WWTP received a portion of industrial wastewater and a prioritization method was applied to select non-target features potentially resulting from industrial activities. Approximately 37,000 non-target features were found in the influents of the WWTPs. A number of non-target features (1207) were prioritized as likely of industrial origin and 54 were identified through database spectral matching. The fates of all detected non-target features were assessed through a novel automated trend assignment method. A trend was assigned to each non-target feature based on the normalized intensity profile for each sampling date. Results showed that 73±4% of influent non-target features and the majority of industrial features (89%) were well-removed (i.e., >80% intensity reduction) during biological treatment in all three WWTPs. Advanced treatment removed, on average, an additional 11% of influent non-target features, with no significant differences observed among the different advanced treatment settings. In contrast, when considering a subset of 66 known micropollutants, advanced treatment was necessary to adequately abate these compounds and higher abatement was observed in fresh GAC (7,000-8,000 bed volumes (BVs)) compared to older GAC (18,000-48,000 BVs) (80% vs 56% of micropollutants were well-removed, respectively). Approximately half of the features detected in the WWTP effluents were features newly formed during the various treatment steps. In ozonation, between 1108-3579 features were classified as potential non-target ozonation transformation products (OTPs). No difference could be observed for their removal in GAC filters at the BVs investigated (70% of OTPs were well-removed on average). Similar amounts (67%) was observed with PAC (7.7-13.6 mg/L) dosed onto a sand filter, demonstrating that a post-treatment with activated carbon is efficient for the removal of OTPs.
Schollée, J. E.; Hollender, J.; McArdell, C. S. (2021) Characterization of advanced wastewater treatment with ozone and activated carbon using LC-HRMS based non-target screening with automated trend assignment, Water Research, 200, 117209 (13 pp.), doi:10.1016/j.watres.2021.117209, Institutional Repository

Removal of pharmaceuticals from human urine during storage, aerobic biological treatment, and activated carbon adsorption to produce a safe fertilizer

Urine has great potential to be an effective fertilizer due to its high nutrient content, however, it can contain potentially worrying pharmaceuticals. Our objective was to study whether urine storage and aerobic biological treatment, i.e. nitrification, was sufficient to remove pharmaceuticals or an additional treatment with activated carbon was necessary to produce a fertilizer from urine. We investigated the abatement of twelve pharmaceuticals, including antibiotics and antivirals, in laboratory experiments representing the treatment steps of anaerobic storage of source-separated human urine, stabilization using partial and full nitrification under acclimatized and non-acclimatized conditions, and treatment of nitrified urine using powdered activated carbon (PAC). Two-month-long-term storage of urine was insufficient to substantially degrade the pharmaceuticals, except for hydrochlorothiazide (>90%). In the partial and full nitrification fed-batch reactors, atazanavir, ritonavir, and clarithromycin were rapidly removed, with biotransformation rate constants greater than 10 L gSS−1d−1. Darunavir, emtricitabine, trimethoprim, N4-acetylsulfamethoxazole, sulfamethoxazole, atenolol, diclofenac, and hydrochlorothiazide were degraded slowly, with biotransformation rate constants of < 1 L gSS−1d−1. With 200 mg PAC L−1, at least 90% of each investigated pharmaceutical was removed. Yeast estrogen screen tests and bioluminescence inhibition tests revealed efficient removal of estrogenicity (99%) and toxicity (56%) using nitrification, and a reduction of 89% and 64%, respectively, using 200 mg PAC L−1. With our study, we provide biotransformation rate constants of compounds never previously investigated. We also show that a combination of nitrification and PAC adsorption enables the production of a safe fertilizer with sufficiently low pharmaceutical concentrations and no removal of beneficial nutrients.
Özel Duygan, B. D.; Udert, K. M.; Remmele, A.; McArdell, C. S. (2021) Removal of pharmaceuticals from human urine during storage, aerobic biological treatment, and activated carbon adsorption to produce a safe fertilizer, Resources, Conservation and Recycling, 166, 105341 (10 pp.), doi:10.1016/j.resconrec.2020.105341, Institutional Repository

Best available technologies and treatment trains to address current challenges in urban wastewater reuse for irrigation of crops in EU countries

Conventional urban wastewater treatment plants (UWTPs) are poorly effective in the removal of most contaminants of emerging concern (CECs), including antibiotics, antibiotic resistant bacteria and antibiotic resistance genes (ARB&ARGs). These contaminants result in some concern for the environment and human health, in particular if UWTPs effluents are reused for crop irrigation. Recently, stakeholders' interest further increased in Europe, because the European Commission is currently developing a regulation on water reuse. Likely, conventional UWTPs will require additional advanced treatment steps to meet water quality limits yet to be officially established for wastewater reuse. Even though it seems that CECs will not be included in the proposed regulation, the aim of this paper is to provide a technical contribution to this discussion as well as to support stakeholders by recommending possible advanced treatment options, in particular with regard to the removal of CECs and ARB&ARGs. Taking into account the current knowledge and the precautionary principle, any new or revised water-related Directive should address such contaminants. Hence, this review paper gathers the efforts of a group of international experts, members of the NEREUS COST Action ES1403, who for three years have been constructively discussing the efficiency of the best available technologies (BATs) for urban wastewater treatment to abate CECs and ARB&ARGs. In particular, ozonation, activated carbon adsorption, chemical disinfectants, UV radiation, advanced oxidation processes (AOPs) and membrane filtration are discussed with regard to their capability to effectively remove CECs and ARB&ARGs, as well as their advantages and drawbacks. Moreover, a comparison among the above-mentioned processes is performed for CECs relevant for crop uptake. Finally, possible treatment trains including the above-discussed BATs are discussed, issuing end-use specific recommendations which will be useful to UWTPs managers to select the most suitable options to be implemented at their own facilities to successfully address wastewater reuse challenges.
Rizzo, L.; Gernjak, W.; Krzeminski, P.; Malato, S.; McArdell, C. S.; Sanchez Perez, J. A.; Schaar, H.; Fatta-Kassinos, D. (2020) Best available technologies and treatment trains to address current challenges in urban wastewater reuse for irrigation of crops in EU countries, Science of the Total Environment, 710, 136312 (17 pp.), doi:10.1016/j.scitotenv.2019.136312, Institutional Repository

Pilotversuche zur erweiterten Abwasser-behandlung mit granulierter Aktivkohle (GAK) und kombiniert mit Teilozonung (O3/GAK) auf der ARA Glarnerland (AVG). Ergänzende Untersuchungen zur PAK-Dosierung in die biologische Stufe mit S::Select®-Verfahren in Kom

Auf der Kläranlage Glarnerland wurde im Rahmen des Forschungsprojektes «Pilotversuche zur erweiterten Abwasserbehandlung mit granulierter Aktivkohle (GAK) und kombiniert mit Teilozonung (O3/GAK)» die Machbarkeit und Effizienz der genannten Verfahrenstechniken zur Spurenstoffelimination untersucht. Im weiteren Verlauf der Untersuchungen wurde zudem auch die Option der Dosierung von Pulveraktivkohle (PAK) in die biologische Stufe, welche mit dem S::Select®-Verfahren betrieben wird, als Vorstufe zur GAK erprobt.

Ziel der Pilotierung war die Erarbeitung von Entscheidungsgrundlagen zur Auswahl eines optimalen Verfahrens oder einer Verfahrenskombination für die angestrebte Realisierung der Spurenstoffelimination beim Abwasserverband Glarnerland. Zudem sollten Langzeiterfahrungen zum Betrieb von GAK-Filtrationen bezüglich Effizienz, Betrieb und vor allem Standzeiten (erreichte Bettvolumina) von verschiedenen GAK-Typen bei unterschiedlichen Kontaktzeiten bei einem Abwasser mit hohem gelöstem organischen Kohlenstoff (DOC) gesammelt werden.

Die Pilotanlage Vorozonung/GAK-Filtration ging Ende Januar 2017 auf der ARA Glarnerland in Betrieb und wurde im August 2019 ausser Betrieb gesetzt. Es wurden vier verschiedene GAK-Produkte untersucht (CSC «HC HK 1000», CarboTech «Pool W1-3», Jacobi «Aquasorb 5010», CabotNorit «GAC 1020 EN»). Parallel wurden alle GAK-Kolonnen (ausser Jacobi «Aquasorb 5010») während der gesamten Betriebsdauer mit einer Vorozonung bei einer spezifischen Ozondosis von rund 0.2 gO3/gDOC betrieben. [...]
McArdell, C. S.; Böhler, M.; Hernandez, A.; Oltramare, C.; Büeler, A.; Siegrist, H. (2020) Pilotversuche zur erweiterten Abwasser-behandlung mit granulierter Aktivkohle (GAK) und kombiniert mit Teilozonung (O3/GAK) auf der ARA Glarnerland (AVG). Ergänzende Untersuchungen zur PAK-Dosierung in die biologische Stufe mit S::Select®-Verfahren in Kom, 146 p, Institutional Repository
Dulio, V.; Hofman, J.; von der Ohe, P.; Brack, W.; McArdell, C.; Slobodnik, J.; Valsecchi, S.; Regan, F.; Lawler, J.; White, B.; Aït-Aïssa, S.; Reemtsma, T.; Budzinski, H.; Assoumani, A.; Staub, P.-françois (2019) Contaminants of emerging concern in urban wastewater, 21 p, Institutional Repository

Consolidated vs new advanced treatment methods for the removal of contaminants of emerging concern from urban wastewater

Urban wastewater treatment plants (WWTPs) are among the main anthropogenic sources for the release of contaminants of emerging concern (CECs) into the environment, which can result in toxic and adverse effects on aquatic organisms and consequently on humans. Unfortunately, WWTPs are not designed to remove CECs and secondary (e.g., conventional activated sludge process, CAS) and tertiary (such as filtration and disinfection) treatments are not effective in the removal of most CECs entering WWTP. Accordingly, several advanced treatment methods have been investigated for the removal of CECs from wastewater, including consolidated (namely, activated carbon (AC) adsorption, ozonation and membranes) and new (such as advanced oxidation processes (AOPs)) processes/technologies. This review paper gathers the efforts of a group of international experts, members of the NEREUS COST Action ES1403 who for three years have been constructively discussing the state of the art and the best available technologies for the advanced treatment of urban wastewater. In particular, this work critically reviews the papers available in scientific literature on consolidated (ozonation, AC and membranes) and new advanced treatment methods (mainly AOPs) to analyse: (i) their efficiency in the removal of CECs from wastewater, (ii) advantages and drawbacks, (iii) possible obstacles to the application of AOPs, (iv) technological limitations and mid to long-term perspectives for the application of heterogeneous processes, and (v) a technical and economic comparison among the different processes/technologies.
Rizzo, L.; Malato, S.; Antakyali, D.; Beretsou, V. G.; Đolić, M. B.; Gernjak, W.; Heath, E.; Ivancev-Tumbas, I.; Karaolia, P.; Lado Ribeiro, A. R.; Mascolo, G.; McArdell, C. S.; Schaar, H.; Silva, A. M. T.; Fatta-Kassinos, D. (2019) Consolidated vs new advanced treatment methods for the removal of contaminants of emerging concern from urban wastewater, Science of the Total Environment, 655, 986-1008, doi:10.1016/j.scitotenv.2018.11.265, Institutional Repository

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. Differing specific ozone doses in the range of 0.35–0.97 g O3/g DOC were applied to determine the adequate ozone dose to fulfill the requirements of the Swiss water protection act. Based on this assessment, a specific ozone dose of 0.55 g O3/g DOC is recommended at this plant to ensure an average abatement of the twelve selected indicator substances by ≥80% over the whole treatment. A monitoring of 550 substances confirmed that this dose was very efficient to abate a broad range of micropollutants by >79% on average. After ozonation, an additional biological post-treatment is required to eliminate possible negative ecotoxicological effects generated during ozonation caused by biodegradable ozonation transformation products (OTPs) and oxidation by-products (OBPs). Three biological treatments (sand filtration, moving bed, fixed bed) and granular activated carbon (GAC, fresh and pre-loaded) filtration were evaluated as post-treatments after ozonation. In parallel, a fresh GAC filter directly connected to the effluent of the secondary clarifier was assessed. Among the three purely biological post-treatments, the sand filtration performed best in terms of removal of dissolved organic carbon (DOC), assimilable organic carbon (AOC) and total suspended solids (TSS). The fresh activated carbon filtration ensured a significant additional micropollutants abatement after ozonation due to sorption. The relative abatement of the indicator substances ranged between 20 and 89% after 27′000 bed volumes (BV) and was still substantial at 50′000 BV. In an identical GAC filter running in parallel and being fed with the effluent of the secondary clarifier, the elimination was less efficient. Seven primary OTPs (chlorothiazide and six N-oxides) formed during ozonation could be quantified thanks to available reference standards. Their concentration decreased with increasing specific ozone doses with the concomitant formation of other OTPs. The seven OTPs were found to be stable compounds and were not abated in the biological post-treatments. They were sorbed in the fresh GAC filter, but less efficiently than the corresponding parent compounds. Two OBPs, bromate (BrO3−) and N-nitrosodimethylamine (NDMA), were formed during ozonation but did not exceeded 5 μg/L for bromate and 30 ng/L for NDMA at the recommended specific ozone dose of 0.55 g O3/g DOC. NDMA was well abated in all post-treatments (minimum 41% during fixed bed filtration, maximum 83% during fresh GAC filtration), while bromate was very stable as expected.
Bourgin, M.; Beck, B.; Boehler, M.; Borowska, E.; Fleiner, J.; Salhi, E.; Teichler, R.; von Gunten, U.; Siegrist, H.; McArdell, C. S. (2018) 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, Water Research, 129, 486-498, doi:10.1016/j.watres.2017.10.036, Institutional Repository

Organic micropollutant control

About 100,000 chemical substances have economic uses, of which 4,600 substances are produced annually in quantities exceeding 1,000 tons in the OECD member states. During production and disposal, as well as after regular use, a significant portion of these substances will unavoidably enter the aquatic environment, where they can have ecotoxicological effects, such as fish feminization. Organic compounds are increasingly being detected in water bodies and in sewage sludge in low concentration ranges (μg/L and ng/L), being referred to as organic micropollutants. T he removal of micropollutants by conventional municipal wastewater treatment is incomplete and a multitude of compounds are only slightly abated. To significantly reduce eco-toxicological effects of micropollutants in receiving waters and water resources, additional treatment steps (e.g. ozonation or activated carbon adsorption) are required in combination with measures taken at the source. Ozonation requires complete nitrification and it might not be suitable for wastewater with high industrial wastewater fractions and high bromide concentrations due to the production of bromate and increased oxidation by-products. Powdered activated carbon (PAC) addition is already broadly applied. PAC can be recycled to the activated sludge treatment to improve micropollutant removal and therefore reduce PAC consumption. Recently granular activated carbon (GAC) filters are increasingly investigated and built in full scale for micropollutant and dissolved organic carbon (DOC) removal. Additional measures in wastewater treatment should be based on careful micropollutant mass flux studies to identify critical catchment areas so that relevant hot spots can be addressed.
Siegrist, H.; Joss, A.; Boehler, M.; McArdell, C. S.; Ternes, T. (2019) Organic micropollutant control, In: Mannina, G.; Ekama, G.; Ødegaard, H.; Olsson, G. (Eds.), Advances in wastewater treatment, 231-260, doi:10.2166/9781780409719_0231, Institutional Repository

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

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 second-order rate constants for the reactions of the molecular, protonated (CTR, FXF) or deprotonated (HCTZ) forms of these compounds with ozone were determined. All three compounds are very reactive with ozone (apparent second order rate constants at pH 7: kO3,pH7 = 1.7·105 M−1s−1, 8.5·104 M−1s−1 and 9.0·103 M−1s−1 for CTR, HCTZ and FXF, respectively). Transformation product (TP) structures were elucidated using liquid chromatography coupled with high-resolution tandem mass spectrometry, including isotope-labeled standards. For cetirizine and hydrochlorothiazide 8 TPs each and for fexofenadine 7 TPs were identified. The main TPs of cetirizine and fexofenadine are their respective N-oxides, whereas chlorothiazide forms to almost 100% from hydrochlorothiazide. In the bacteria bioluminescence assay the toxicity was slightly increased only during the ozonation of cetirizine at very high cetirizine concentrations. The main TPs detected in bench-scale experiments were also detected in full-scale ozonation of a municipal wastewater, for >90% elimination of the parent compounds.
Borowska, E.; Bourgin, M.; Hollender, J.; Kienle, C.; McArdell, C. S.; von Gunten, U. (2016) Oxidation of cetirizine, fexofenadine and hydrochlorothiazide during ozonation: kinetics and formation of transformation products, Water Research, 94, 350-362, doi:10.1016/j.watres.2016.02.020, Institutional Repository

Hospital-use pharmaceuticals in Swiss waters modeled at high spatial resolution

A model to predict the mass flows and concentrations of pharmaceuticals predominantly used in hospitals across a large number of sewage treatment plant (STP) effluents and river waters was developed at high spatial resolution. It comprised 427 geo-referenced hospitals and 742 STPs serving 98% of the general population in Switzerland. In the modeled base scenario, domestic, pharmaceutical use was geographically distributed according to the population size served by the respective STPs. Distinct hospital scenarios were set up to evaluate how the predicted results were modified when pharmaceutical use in hospitals was allocated differently; for example, in proportion to number of beds or number of treatments in hospitals. The hospital scenarios predicted the mass flows and concentrations up to 3.9 times greater than in the domestic scenario for iodinated X-ray contrast media (ICM) used in computed tomography (CT), and up to 6.7 times greater for gadolinium, a contrast medium used in magnetic resonance imaging (MRI). Field measurements showed that ICM and gadolinium were predicted best by the scenarios using number of beds or treatments in hospitals with the specific facilities (i.e., CT and/or MRI). Pharmaceuticals used both in hospitals and by the general population (e.g., cyclophosphamide, sulfamethoxazole, carbamazepine, diclofenac) were predicted best by the scenario using the number of beds in all hospitals, but the deviation from the domestic scenario values was only small. Our study demonstrated that the bed number-based hospital scenarios were effective in predicting the geographical distribution of a diverse range of pharmaceuticals in STP effluents and rivers, while the domestic scenario was similarly effective on the scale of large river-catchments.
Kuroda, K.; Itten, R.; Kovalova, L.; Ort, C.; Weissbrodt, D. G.; McArdell, C. S. (2016) Hospital-use pharmaceuticals in Swiss waters modeled at high spatial resolution, Environmental Science and Technology, 50(9), 4742-4751, doi:10.1021/acs.est.6b00653, Institutional Repository

Prediction of micropollutant elimination during ozonation of a hospital wastewater effluent

Determining optimal ozone doses for organic micropollutant elimination during wastewater ozonation is challenged by the presence of a large number of structurally diverse micropollutants for varying wastewater matrice compositions. A chemical kinetics approach based on ozone and hydroxyl radical (·OH) rate constant and measurements of ozone and ·OH exposures is proposed to predict the micropollutant elimination efficiency. To further test and validate the chemical kinetics approach, the elimination efficiency of 25 micropollutants present in a hospital wastewater effluent from a pilot-scale membrane bioreactor (MBR) were determined at pH 7.0 and 8.5 in bench-scale experiments with ozone alone and ozone combined with H2O2 as a function of DOC-normalized specific ozone doses (gO3/gDOC). Furthermore, ozone and ·OH exposures, ·OH yields, and ·OH consumption rates were determined. Consistent eliminations as a function of gO3/gDOC were observed for micropollutants with similar ozone and OH rate constants. They could be classified into five groups having characteristic elimination patterns. By increasing the pH from 7.0 to 8.5, the elimination levels increased for the amine-containing micropollutants due to the increased apparent second-order ozone rate constants while decreased for most micropollutants due to the diminished ozone or ·OH exposures. Increased ·OH quenching by effluent organic matter and carbonate with increasing pH was responsible for the lower ·OH exposures. Upon H2O2 addition, the elimination levels of the micropollutants slightly increased at pH 7 (<8%) while decreased considerably at pH 8.5 (up to 31%). The elimination efficiencies of the selected micropollutants could be predicted based on their ozone and ·OH rate constants (predicted or taken from literature) and the determined ozone and ·OH exposures. Reasonable agreements between the measured and predicted elimination levels were found, demonstrating that the proposed chemical kinetics method can be used for a generalized prediction of micropollutant elimination during wastewater ozonation. Out of 67 analyzed micropollutants, 56 were present in the tested hospital wastewater effluent. Two-thirds of the present micropollutants were found to be ozone-reactive and efficiently eliminated at low ozone doses (e.g., >80% for gO3/gDOC = 0.5).
Lee, Y.; Kovalova, L.; McArdell, C. S.; von Gunten, U. (2014) Prediction of micropollutant elimination during ozonation of a hospital wastewater effluent, Water Research, 64, 134-148, doi:10.1016/j.watres.2014.06.027, Institutional Repository

Urban wastewater treatment plants as hotspots for the release of antibiotics in the environment: a review

Urban wastewater treatment plants (UWTPs) are among the main sources of antibiotics' release into various compartments of the environment worldwide. The aim of the present paper is to critically review the fate and removal of various antibiotics in wastewater treatment, focusing on different processes (i.e. biological processes, advanced treatment technologies and disinfection) in view of the current concerns related to the induction of toxic effects in aquatic and terrestrial organisms, and the occurrence of antibiotics that may promote the selection of antibiotic resistance genes and bacteria, as reported in the literature. Where available, estimations of the removal of antibiotics are provided along with the main treatment steps. The removal efficiency during wastewater treatment processes varies and is mainly dependent on a combination of antibiotics' physicochemical properties and the operating conditions of the treatment systems. As a result, the application of alternative techniques including membrane processes, activated carbon adsorption, advanced oxidation processes (AOPs), and combinations of them, which may lead to higher removals, may be necessary before the final disposal of the effluents or their reuse for irrigation or groundwater recharge.
Michael, I.; Rizzo, L.; McArdell, C. S.; Manaia, C. M.; Merlin, C.; Schwartz, T.; Dagot, C.; Fatta-Kassinos, D. (2013) Urban wastewater treatment plants as hotspots for the release of antibiotics in the environment: a review, Water Research, 47(3), 957-995, doi:10.1016/j.watres.2012.11.027, Institutional Repository

Elimination of micropollutants during post-treatment of hospital wastewater with powdered activated carbon, ozone, and UV

A pilot-scale hospital wastewater treatment plant consisting of a primary clarifier, membrane bioreactor, and five post-treatment technologies including ozone (O3), O3/H2O2, powdered activated carbon (PAC), and low pressure UV light with and without TiO2 was operated to test the elimination efficiencies for 56 micropollutants. The extent of the elimination of the selected micropollutants (pharmaceuticals, metabolites and industrial chemicals) was successfully correlated to physical-chemical properties or molecular structure. By mass loading, 95% of all measured micropollutants in the biologically treated hospital wastewater feeding the post-treatments consisted of iodinated contrast media (ICM). The elimination of ICM by the tested post-treatment technologies was 50–65% when using 1.08 g O3/gDOC, 23 mg/L PAC, or a UV dose of 2400 J/m2 (254 nm). For the total load of analyzed pharmaceuticals and metabolites excluding ICM the elimination by ozonation, PAC, and UV at the same conditions was 90%, 86%, and 33%, respectively. Thus, the majority of analyzed substances can be efficiently eliminated by ozonation (which also provides disinfection) or PAC (which provides micropollutants removal, not only transformation). Some micropollutants recalcitrant to those two post-treatments, such as the ICM diatrizoate, can be substantially removed only by high doses of UV (96% at 7200 J/m2). The tested combined treatments (O3/H2O2 and UV/TiO2) did not improve the elimination compared to the single treatments (O3 and UV).
Kovalova, L.; Siegrist, H.; von Gunten, U.; Eugster, J.; Hagenbuch, M.; Wittmer, A.; Moser, R.; McArdell, C. S. (2013) Elimination of micropollutants during post-treatment of hospital wastewater with powdered activated carbon, ozone, and UV, Environmental Science and Technology, 47(14), 7899-7908, doi:10.1021/es400708w, Institutional Repository

Hospital wastewater treatment by membrane bioreactor: performance and efficiency for organic micropollutant elimination

A pilot-scale membrane bioreactor (MBR) was installed and operated for one year at a Swiss hospital. It was fed an influent directly from the hospital’s sanitary collection system. To study the efficiency of micropollutant elimination in raw hospital wastewater that comprises a complex matrix with micropollutant concentrations ranging from low ng/L to low mg/L, an automated online SPE-HPLC-MS/MS analytical method was developed. Among the 68 target analytes were the following: 56 pharmaceuticals (antibiotics, antimycotics, antivirals, iodinated X-ray contrast media, antiinflamatory, cytostatics, diuretics, beta blockers, anesthetics, analgesics, antiepileptics, antidepressants, and others), 10 metabolites, and 2 corrosion inhibitors. The MBR influent contained the majority of those target analytes. The micropollutant elimination efficiency was assessed through continuous flow-proportional sampling of the MBR influent and continuous time-proportional sampling of the MBR effluent. An overall load elimination of all pharmaceuticals and metabolites in the MBR was 22%, as over 80% of the load was due to persistent iodinated contrast media. No inhibition by antibacterial agents or disinfectants from the hospital was observed in the MBR. The hospital wastewater was found to be a dynamic system in which conjugates of pharmaceuticals deconjugate and biological transformation products are formed, which in some cases are pharmaceuticals themselves.
Kovalova, L.; Siegrist, H.; Singer, H.; Wittmer, A.; McArdell, C. S. (2012) Hospital wastewater treatment by membrane bioreactor: performance and efficiency for organic micropollutant elimination, Environmental Science and Technology, 46(3), 1536-1545, doi:10.1021/es203495d, Institutional Repository

Elimination of organic micropollutants in a municipal wastewater treatment plant upgraded with a full-scale post-ozonation followed by sand filtration

The removal efficiency for 220 micropollutants was studied at the scale of a municipal wastewater treatment plant (WWTP) upgraded with post-ozonation followed by sand filtration. During post-ozonation, compounds with activated aromatic moieties, amine functions, or double bonds such as sulfamethoxazole, diclofenac, or carbamazepine with second-order rate constants for the reaction with ozone >104 M−1 s−1 at pH 7 (fast-reacting) were eliminated to concentrations below the detection limit for an ozone dose of 0.47 g O3 g−1 dissolved organic carbon (DOC). Compounds more resistant to oxidation by ozone such as atenolol and benzotriazole were increasingly eliminated with increasing ozone doses, resulting in >85% removal for a medium ozone dose (0.6 g O3 g−1 DOC). Only a few micropollutants such as some X-ray contrast media and triazine herbicides with second-order rate constants <102 M−1 s−1 (slowly reacting) persisted to a large extent. With a medium ozone dose, only 11 micropollutants of 55 detected in the secondary effluent were found at >100 ng L−1. The combination of reaction kinetics and reactor hydraulics, based on laboratory- and full-scale data, enabled a quantification of the results by model calculations. This conceptual approach allows a direct upscaling from laboratory- to full-scale systems and can be applied to other similar systems. The carcinogenic by-products N-nitrosodimethylamine (NDMA) (≤14 ng L−1) and bromate (<10 μg L−1) were produced during ozonation, however their concentrations were below or in the range of the drinking water standards. Furthermore, it could be demonstrated that biological sand filtration is an efficient additional barrier for the elimination of biodegradable compounds formed during ozonation such as NDMA. The energy requirement for the additional post-ozonation step is about 0.035 kWh m−3, which corresponds to 12% of a typical medium-sized nutrient removal plant (5 g DOC m−3).
Hollender, J.; Zimmermann, S. G.; Koepke, S.; Krauss, M.; McArdell, C. S.; Ort, C.; Singer, H.; von Gunten, U.; Siegrist, H. (2009) Elimination of organic micropollutants in a municipal wastewater treatment plant upgraded with a full-scale post-ozonation followed by sand filtration, Environmental Science and Technology, 43(20), 7862-7869, doi:10.1021/es9014629, Institutional Repository

Removal of pharmaceuticals and fragrances in biological wastewater treatment

The removal of seven pharmaceuticals and two fragrances in the biological units of various full-scale municipal wastewater treatment plants was studied. The observed removal of pharmaceuticals was mainly due to biological transformation and varied from insignificant (10%, carbamazepine) to>90% (ibuprofen). However, no quantitative relationship between structure and activity can be set up for the biological transformation. Overall, it can be concluded that for compounds showing a sorption coefficient (Kd) of below 300 L kg-1, sorption onto secondary sludge is not relevant and their transformation can consequently be assessed simply by comparing influent and effluent concentrations. The two fragrances (HHCB, AHTN) studied were mainly removed by sorption onto sludge. For the compounds studied, comparable transformation and sorption was seen for different reactor types (conventional activated sludge, membrane bioreactor and fixed bed reactor) as well as for sludge ages between 10 and 60-80 days and temperatures between 12 °C and 21 °C. However, some significant variations in the observed removal currently lack an explanation. The observed incoming daily load of iopromide and roxithromycin in medium-sized municipal wastewater treatment plants (up to 80,000 population equivalents) is generated by only a small number of patients: the consequences for representative 24 h composite sampling are discussed. Generally, the paper presents a method for setting up mass balances for micropollutants over entire wastewater treatment plants, including an estimation of the accuracy of the quantified fate (i.e. removal by sorption and biological transformation).
Joss, A.; Keller, E.; Alder, A. C.; Göbel, A.; McArdell, C. S.; Ternes, T.; Siegrist, H. (2005) Removal of pharmaceuticals and fragrances in biological wastewater treatment, Water Research, 39(14), 3139-3152, doi:10.1016/j.watres.2005.05.031, Institutional Repository

Occurrence and sorption behavior of sulfonamides, macrolides, and trimethoprim in activated sludge treatment

The occurrence of sulfonamide and macrolide antimicrobials, as well as trimethoprim, was investigated in conventional activated sludge treatment. Average daily loads in untreated wastewater correlated well with those estimated from annual consumption data and pharmacokinetic behavior. Considerable variations were found during a day, and seasonal differences seem to occur for the macrolides, probably caused by a higher consumption of these substances in winter. The most predominant macrolide and sulfonamide antimicrobials were clarithromycin and sulfamethoxazole, respectively. In the case of sulfamethoxazole, the main human metabolite, N4- acetylsulfamethoxazole, was included as an analyte, accounting for up to 86% of the total load in untreated wastewater. The results obtained illustrate the importance of considering retransformable substances, for example human metabolites, when investigating the behavior and fate of pharmaceuticals, Average concentrations of sulfapyridine, sulfamethoxazole, trimethoprim, azithromycin, and clarithromycin in activated sludge ranged between 28 and 68 μg/kg of dry weight. Overall the sorption to activated sludge was shown to be low for the investigated antimicrobials, with estimated sorption constants for activated sludge below 500 L/kg. Elimination in activated sludge treatment was found to be incomplete for all investigated compounds. In final effluents, the median concentrations for sulfamethoxazole and clarithromycin were 290 and 240 ng/L, respectively.
Göbel, A.; Thomsen, A.; McArdell, C. S.; Joss, A.; Giger, W. (2005) Occurrence and sorption behavior of sulfonamides, macrolides, and trimethoprim in activated sludge treatment, Environmental Science and Technology, 39(11), 3981-3989, doi:10.1021/es048550a, Institutional Repository

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activated carbon, wastewater treatment, mass fluxes, micropollutants, ozonation

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