The field of high-resolution mass spectrometry has undergone a rapid progress in the last years due to instrumental improvements leading to a higher sensitivity and selectivity of instruments. A variety of qualitative screening approaches, summarized as nontarget screening, have been introduced and have successfully extended the environmental monitoring of organic micropollutants. Several automated data processing workflows have been developed to handle the immense amount of data that are recorded in short time frames by these methods. Most data processing workflows include similar steps, but underlying algorithms and implementation of different processing steps vary. In this study the consistency of data processing with different software tools was investigated. For this purpose, the same raw data files were processed with the software packages MZmine2, enviMass, Compound Discoverer, and XCMS online and resulting feature lists were compared. Results show a low coherence between different processing tools, as overlap of features between all four programs was around 10%, and for each software between 40% and 55% of features did not match with any other program. The implementation of replicate and blank filter was identified as one of the sources of observed divergences. However, there is a need for a better understanding and user instructions on the influence of different algorithms and settings on feature extraction and following filtering steps. In future studies it would be of interest to investigate how final data interpretation is influenced by different processing software. With this work we want to encourage more awareness on data processing as a crucial step in the workflow of nontarget screening.

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Effluents from municipal wastewater treatment plants (WWTPs) are known to be point sources of micropollutants for surface waters. The aim of this study was to examine a reconstructed full-scale ozonation equipped with a pump-injector system for ozone (O) dosage and a fluidized moving-bed reactor as biological posttreatment at a municipal WWTP utilizing an effect-directed approach. This approach consists of chemical analysis in combination with toxicological tests for the assessment of treatment efficiency of the plant. Chemical analysis showed elimination rates > 80% for pharmaceuticals and industrial chemicals. Analysis of endocrine disruptors was limited due to substance concentrations below the limit of detection (LOD). Estrogenic activity was detected by the Arxula Adeninivorans yeast estrogen screen (A-YES) at low concentrations (pg to ng EEQ/l range). Estrogenic activity was reduced by more than 90% after ozonation. In contrast, androgenic activity (measured in the Adeninivorans yeast androgen screen, A-YAS) was still found after O treatment and after biological posttreatment, which is consistent with the data obtained by chemical analysis. Furthermore, no marked genotoxic or cytotoxic effects were observed after ozonation using the alkaline comet and 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazoliumbromid (MTT) assays, respectively. Results suggest that the applied specific O dose of 0.4 mg/mg is a safe operation setup in terms of toxicologically relevant transformation products. In addition, no adverse effects on primary producers, as evidenced by algae growth inhibition tests, were detected. The monitored biofilm growth in the biological posttreatment exhibited a steady state after one month. Based on computational fluid dynamics (CFD) simulations and biomass, one might conclude that O did not apparently enter biological posttreatment to a great extent and that hydraulic retention time in the O reactor was sufficient. Our data demonstrate the effectiveness of a full-scale O treatment in combination with a fluidized moving-bed reactor as biological posttreatment for the reduction of a majority of micropollutants without the release of relevant toxic transformation products as assessed by a chemical and toxicity-based approach.

Endocrine-disrupting chemicals are mainly discharged into the environment by wastewater treatment plants (WWTPs) and are known to induce adverse effects in aquatic life. Advanced treatment with ozone successfully removes such organic micropollutants, but an increase of estrogenic effects after the ozonation of hospital wastewater was observed in previous studies. In order to investigate this effect, estrogenic and androgenic as well as anti-estrogenic and anti-androgenic activities were observed during treatment of hospital wastewater using three different effect-based reporter gene bioassays. Despite different matrix influences, sensitivities, and test-specific properties, all assays used obtained comparable results. Estrogenic and androgenic activities were mainly reduced during the biological treatment and further removed during ozonation and sand filtration, resulting in non-detectable agonistic activities in the final effluent. An increased estrogenic activity after ozonation could not be observed in this study. Antagonistic effects were removed in the biological treatment by up to 50 % without further reduction in the advanced treatment. Due to the presence of antagonistic substances within the wastewater, masking effects were probable. Therefore, this study showed the relevance of antagonistic activities at hospital WWTPs and illustrates the need for a better understanding about antagonistic effects.