Eaux usées

Strategies to determine the removal efficiency of micropollutants in wastewater treatment plants (WWTPs) are widely discussed. Especially the evaluation of the potential benefit of further advanced treatment steps such as an additional tertiary treatment based on ozonation or activated carbon have come into focus. Such evaluation strategies are often based on the removal behavior of known micropollutants via target or suspected analysis. The utilization of nontarget analysis is considered to lead to a more comprehensive picture as also unknown or not expected micropollutants are analyzed. Here, the results of an evaluation via target and nontarget analysis were compared for biological treatment (BT) processes of eleven full-scale WWTPs and three different post-treatments (PTs): one sand filter (SF) and two granular activated carbon (GAC) filters. The similarity of the determined removals from target and nontarget analysis of the BTs increased significantly by excluding easily degradable "features" from the nontarget evaluation. A similar ranking of the removal trends for the BTs could also be achieved by comparing this new subset of nontarget features with a set of nine readily to moderately biodegradable micropollutants. This observation suggests that a performance ranking of BTs based either on target or nontarget analysis is plausible. In contrast to the BTs, the evaluation of the three PTs revealed that the difference of feature removal between SF and the two GACs was small, but large for the target analytes with substantially higher removal effciencies for the GACs compared to the SF. In addition to the removal behavior, the nontarget analysis provided further information about the number and quantity of transformation products (TPs) in the effluent from the BTs. For all BTs more than half (55–67%) of the features detected in the effluent were not found in the influent. A comparable proportion of TPs was also detected after GAC and sand filtration due to their microbial activities.

Ozone treatment is an effective barrier against viral pathogens, wherefore 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 virus inactivation in real-time. The goal of this work was to identify easy-to-measure proxies to monitor virus inactivation during water and wastewater treatment by ozone. Proxies considered were the abatement in UV absorbance at 254 nm (UV₂₅₄) and carbamazepine (CBZ), a ubiquitous organic micropollutant with a similar abatement rate constant as human viruses. The proxies, as well as the inactivation of two viruses (MS2 coliphage and coxsackievirus B5) were measured in surface water and in a secondary wastewater effluent as a function of the specific ozone dose (mgO₃/mg dissolved organic carbon). Virus inactivation was rapid in both matrices, but was more efficient in surface water. This trend was also evident when inactivation was assessed as a function of the ozone exposure to account for the different ozone demand of the two water types. Both proxies, as well as the specific ozone dose, were correlated with virus inactivation. The correlations depended only weakly on the virus species, but – with the exception of CBZ abatement – differed between the two water types. Finally, predictive relationships were established using Bayesian power models, to estimate virus inactivation based on the measurement of a proxy. The models were then applied to estimate the MS2 inactivation in a pilot-scale ozone reactor that treats surface water of Lake Zurich. All proxies yielded good estimates of the actual MS2 inactivation in the pilot plant, indicating that the proxy-inactivation relationships established in the laboratory can also be applied to flow-through reactors. This study confirms that ozone is a highly effective disinfectant for viruses in both surface water and wastewater, and that the abatement of UV₂₅₄ and CBZ can be used to track virus inactivation during water and wastewater treatment.

Efforts to predict the environmental fate of engineered nanomaterials (ENMs) are frequently based on the physiochemical properties and behavior of the ENMs in their pristine, “as-produced” state. However, it is well-established that ENMs can be physically, biologically, and chemically transformed, resulting in altered physiochemical properties and behavior. Wastewater treatment plants (WWTPs) represent an important stage in an ENM's life-cycle where they can be transformed. To better understand the properties of ENMs discharged from WWTPs into surface waters, we investigated how the transformation processes of aggregation and corona formation are influenced by the surface coating applied to ENMs during their manufacture. Using 40 nm gold nanoparticles coated with polyethylene glycol, lipoic acid, or branched polyethylenimine as model ENMs, batch experiments were performed to investigate aggregation and corona formation during the primary clarification and activated sludge treatment stages. A tangential flow filtration system was used to evaluate if the initial transformations were altered as the aquatic chemistry of the background matrix was changed, mimicking the varying conditions ENMs would experience during transport through a WWTP. Using a combination of corroborative techniques including dynamic light scattering, phase analysis light scattering, ultraviolet-visible light spectroscopy, and transmission electron microscopy, we find that the model ENMs aggregated in each wastewater matrix, regardless of the initial surface coating. Differences in the UV-vis spectra indicate that the nature of the corona acquired by the ENMs differed as a function of the surface coating of the pristine ENMs. In addition, initial ENM transformations during exposure to the influent wastewater persisted even as the background matrix changed. These results support the finding that ENMs discharged from WWTPs will not resemble their pristine analogs. Furthermore, the corona acquired by ENMs in WWTPs may vary in relation to their pristine properties and be dictated by conditions during early stage exposures.

This study presents the development and validation of a comprehensive quantitative target methodology for the analysis of 2316 emerging pollutants in water based on Ultra-Performance Liquid Chromatography Quadrupole-Time-Of-Flight Mass Spectrometry (UPLC-Q-ToF-HRMS/MS). Target compounds include pesticides, pharmaceuticals, drugs of abuse, industrial chemicals, doping compounds, surfactants and transformation products, among others. The method was validated for 195 analytes, chosen to be representative of the chemical space of the target list, enabling the assessment of the performance of the method. The method involves a generic sample preparation based on mixed mode solid phase extraction, a UPLC-QTOF-MS/MS screening method using Data Independent Acquisition (DIA) mode, which provides MS and MS/MS spectra simultaneously and an elaborate strong post-acquisition evaluation of the data. The processing method was optimized to provide a successful identification rate >95 % and to minimize the number of false positive results (< 5 %). Decision limit (CCα) and detection capability (CCβ) were also introduced in the validation scheme to provide more realistic metrics on the performance of a HRMS-based wide-scope screening method. A new system of identification points (IPs) based on the one described in the Commission Decision 2002/657/EC was applied to communicate the confidence level in the identification of the analytes. This system considers retention time, mass accuracy, isotopic fit and fragmentation; taking full advantage of the capacities of the HRMS instruments. Finally, 398 contaminants were detected and quantified in real wastewater.

The sorption of thallium (Tl) onto manganese (Mn) oxides critically influences its environmental fate and geochemical cycling and is also of interest in water treatment. Combined quantitative and mechanistic understanding of Tl sorption onto Mn oxides, however, is limited. We investigated the uptake of dissolved Tl(I) by environmentally relevant phyllo- and tectomanganates and used X-ray absorption spectroscopy to determine the oxidation state and local coordination of sorbed Tl. We show that extremely strong sorption of Tl onto vacancy-containing layered δ-MnO₂ at low dissolved Tl(I) concentrations (log K_d ≥ 7.4 for ≤10^-8 M Tl(I); K_d in (L/kg)) is due to oxidative uptake of Tl and that less specific nonoxidative Tl uptake only becomes dominant at very high Tl(I) concentrations (>10^-6 M). Partial reduction of δ-MnO₂ induces phase changes that result in inhibited oxidative Tl uptake and lower Tl sorption affinity (log K_d 6.2-6.4 at 10^-8 M Tl(I)) and capacity. Triclinic birnessite, which features no vacancy sites, and todorokite, a 3 × 3 tectomanganate, bind Tl with lower sorption affinity than δ-MnO₂, mainly as hydrated Tl⁺ in interlayers (triclinic birnessite; log K_d 5.5 at 10^-8 M Tl(I)) or tunnels (todorokite). In cryptomelane, a 2 × 2 tectomanganate, dehydrated Tl⁺ replaces structural K⁺. The new quantitative and mechanistic insights from this study contribute to an improved understanding of the uptake of Tl by key Mn oxides and its relevance in natural and engineered systems.

Niederschlags- und Mischabwasserentlastungen aus Siedlungen tragen zu Mikroverunreinigungen in Gewässern bei. Mit Passivsammlern wurden erstmals Konzentrationsbereiche an 20 Standorten für insgesamt 95 Ereignisse bestimmt, was die Analyse von Unterschieden zwischen Standorten sowie die Identifikation relevanter Eintragspfade unterstützt. An 13 Standorten waren bei mindestens einer Substanz die Konzentrationen im Mischabwasser höher als akute Qualitätskriterien.

Durch die Belastung mit Antibiotika können sich in der Umwelt vermehrt Resistenzen dagegen bilden, was eine potenzielle Gefahr für die menschliche Gesundheit darstellt. Antibiotikaresistenzbildung wird zurzeit nicht in der Methode zu Herleitung von Umweltqualitätskriterien (UQK) berücksichtigt. Nun wurde für acht Antibiotika untersucht, ob die verfügbaren UQK auch protektiv für Antibiotikaresistenzbildung sind. Basierend auf diesem Vergleich werden Handlungs- sowie Forschungsvorschläge abgeleitet.

Die ARA Sihltal wird heute ohne Vorklärung betrieben, soll jedoch aufgrund der zukünftigen Bevölkerungsentwicklung und zur energetischen Optimierung mit einer Vorklärung erweitert werden. Wegen der sehr engen Platzverhältnisse kann eine maschinelle Vorklärung (Trommelsieb) einfacher realisiert werden als eine konventionelle Vorklärung. Die Pilotversuche bestätigen, dass das Trommelsieb aus betrieblicher Sicht und bezüglich Abscheideleistung eine gleichwertige Vorklärung bietet.