Do contaminants originating from state-of-the-art treated wastewater impact the ecological quality of surface waters?

Since the 1980s, advances in wastewater treatment technology have led to considerably improved surface water quality in the urban areas of many high income countries. However, trace concentrations of organic wastewater-associated contaminants may still pose a key environmental hazard impairing the ecological quality of surface waters. To identify key impact factors, we analyzed the effects of a wide range of anthropogenic and environmental variables on the aquatic macroinvertebrate community. We assessed ecological water quality at 26 sampling sites in four urban German lowland river systems with a 0–100% load of state-of-the-art biological activated sludge treated wastewater. The chemical analysis suite comprised 12 organic contaminants (five phosphor organic flame retardants, two musk fragrances, bisphenol A, nonylphenol, octylphenol, diethyltoluamide, terbutryn), 16 polycyclic aromatic hydrocarbons, and 12 heavy metals. Non-metric multidimensional scaling identified organic contaminants that are mainly wastewater-associated (i.e., phosphor organic flame retardants, musk fragrances, and diethyltoluamide) as a major impact variable on macroinvertebrate species composition. The structural degradation of streams was also identified as a significant factor. Multiple linear regression models revealed a significant impact of organic contaminants on invertebrate populations, in particular on Ephemeroptera, Plecoptera, and Trichoptera species. Spearman rank correlation analyses confirmed wastewater-associated organic contaminants as the most significant variable negatively impacting the biodiversity of sensitive macroinvertebrate species. In addition to increased aquatic pollution with organic contaminants, a greater wastewater fraction was accompanied by a slight decrease in oxygen concentration and an increase in salinity. This study highlights the importance of reducing the wastewater-associated impact on surface waters. For aquatic ecosystems in urban areas this would lead to: (i) improvement of the ecological integrity, (ii) reduction of biodiversity loss, and (iii) faster achievement of objectives of legislative requirements, e.g., the European Water Framework Directive

Influence of ozonation and activated carbon treatment on the ecotoxicity of wastewater treatment plant effluents

Background. There is growing public and scientific concern about the occurrence of anthropogenic chemicals in the aquatic environment. Surface and groundwater serve as main drinking water resource. Especially in metropolitan areas these water reservoirs are impacted by organic pollutants predominantly originating from wastewater treatment plant (WWTP) effluents. The impact of wastewater derived anthropogenic chemicals is therefore related to environmental and human health concerns. In order to lower the potential environmental and human health risk from wastewater associated pollutants, strategies for enhanced pollutant removal are applicable in a medium-term perspective. Ozonation and powdered activated carbon treatment are the two advanced wastewater treatment technologies, which are technically mature as well as economically feasible for the application in large-scale wastewater treatment plants. While powdered activated carbon removes substances by adsorption, ozonation degrades a parent compound into oxidation products. Most of the available research has been done at lab-scale while onsite ecotoxicity tests and chemical analyses are rare. Objectives. For a comparative evaluation of advanced wastewater treatments' potential to alter toxicity, a broad spectrum of ecotoxicological data need to be collected. The focus has been set on three major objectives: A) Evaluation of the endocrine activity; B) Evaluation of the unspecific toxicity; C) Evaluation of genotoxicity and mutagenicity. Methods. The advanced treatment methods, ozonation and powdered activated carbon treatment of secondary wastewater effluents, – each equipped with subsequent sand filtration as additional post treatment step – were ecotoxico-logically characterized at a pilot-scale WWTP. For process control the elimination of 35 selected pharmaceuticals was identified by chemical analyses using HPLC-MS/MS. The endocrine activity ((anti-)estrogenic, (anti-)androgenic, dioxin-like activity)) was characterized by yeast-based in vitro bioassays and cytotoxicity by cell based assays. Genotoxicity and mutagenicity was assessed using umuC'assay and Ames assay, respectively. All in vitro assays were performed using extracts of the wastewater samples. In vivo toxicity was assessed with the fish early life stage test with rainbow trout (Oncorhynchus mykiss). Ozonation was additionally assessed at a full-scale WWTP with in-vitro tests on endocrine activity and cytotoxicity and in vivo toxicity tests using five aquatic model organisms: Lemna minor, Daphnia magna, Chironomus riparius, Lumbriculus variegatus, Potamopyrgus antipodarum. Results. In conventional activated sludge treated effluents the residual estrogenicity, antiandrogenicity, aryl hydrocarbon receptor agonistic activity and cytotoxicity were considerably reduced while antiestrogenicity was increased by both advanced treatment technologies. Ozonation led to an increase in genotoxic effects detected with Ames assay and with single cell gel electrophoresis of rainbow trout erythrocytes. Furthermore, mortality of rainbow trout was increased and reproduction of L. variegatus was decreased. Sand filtration lessened the genotoxic effects and adjusted reproduction of L. variegatus and mortality of rainbow trout to a similar level as conventional treatment. Conclusions. This work demonstrates that conventional activated sludge treatment induces in vitro and in vivo toxicity. Advanced wastewater treatment combined with subsequent sand filtration can reduce in vitro and in vivo toxicity. An observed increase of endocrine activity after advanced wastewater treatment is an indication for different removal efficiencies of chemicals causing agonistic or antagonistic activity, respectively. Ozonation of wastewater generates ecotoxicity, which is largely removed by subsequent sand filtration. After a comprehensive investigation and after assurance of the removal of adverse effects, advanced treatment technologies could have beneficial effects on the ecological quality of the receiving water.Das Vorkommen von Chemikalien anthropogenen Ursprungs in der aquatischen Umwelt ist für Wissenschaft und Gesellschaft von außerordentlichem Interesse. Besonders in dicht besiedelten Regionen werden Oberflächen- und Grundwasser als Trinkwasserressource in erheblichem Maße genutzt. Diese Wasserreservoire sind jedoch häufig noch mit organischen, aus Kläranlagen entlassenen Substanzen und Schadstoffen belastet. Abwasserbürtige Chemikalien können somit potentiell die aquatische Biozönose und auch die menschliche Gesundheit beeinflussen. Kommunale Kläranlagen, die mit dem biologischen Belebtschlammverfahren arbeiten, haben die primäre Aufgabe, Nährstoffe, wie anorganischen Stickstoff (Nitrat, Ammonium, Nitrit), Phosphate und adsorbierbare (Schwer') Metalle, zu reduzieren. Bei diesem Reinigungsprozess werden auch organische Chemikalien zu einem erheblichen Teil biologisch abgebaut oder vom Klärschlamm adsorbiert und somit aus der Wasserphase entfernt. Hier gibt es Einzelstoffe oder Stoffgruppen, die nur zu einem geringen Anteil biologisch und/oder vom Klärschlamm kaum adsorptiv entfernbar sind und somit kontinuierlich in Oberflächengewässer eingeleitet werden. Unter ihnen befinden sich Substanzen mit hoher biologischer Wirksamkeit, neben Pharmaka auch Substanzen aus Konsumartikeln, wie Flammschutzmitteln, UV-Schutzmitteln, Additive aus Plastikverpackungen, Kosmetika und Kleidung, Pestizide und Inhaltsstoffe weiterer Haushaltschemikalien. Seit Mitte der neunziger Jahre stehen diese Substanzen im Fokus der Aufmerksamkeit, da die instrumentelle Ausrüstung von Geräten und die Techniken zur chemischen Analyse im Nano' bis Pikogramm-Bereich befähigt wurde. Einige dieser Chemikalien, die in Kläranlagen nur mäßigem Abbau unterliegen, stehen im Verdacht, auch in niedrigen Konzentrationsbereichen Effekte in der aquatischen Flora und Fauna zu verursachen. Die Datenlage zu chronischen Toxizitätstests mit abwasserrelevanten Substanzen im Spurenbereich ist unvollständig. Dies gilt insbesondere für die Situation in abwasserbelasteten Oberflächengewässern, da es sich dabei um Mischungen einer großen Anzahl von Chemikalien handelt. Um das von Abwasser ausgehende Risiko durch eine Reduktion von organischen Schadstoffen zu minimieren, sind sogenannte End'of'Pipe'Techniken mittelfristig anwendbar. Ozonierung als oxidatives Verfahren und Pulveraktivkohlebehandlung als adsorptives Verfahren sind dabei zwei erweiterte Abwasserbehandlungstechniken, die sowohl technisch ausgereift als auch aus ökonomischer Sicht im großtechnischen Maßstab durchführbar sind. Während Pulveraktivkohle Substanzen durch Adsorption entfernt, baut die Ozonierung die Ausgangssubstanzen überwiegend zu Oxidationsprodukten ab. Die meisten Oxidationsprodukte werden jedoch im Ozonreaktor nicht vollständig mineralisiert und die wenigsten sind strukturell aufgeklärt noch ökotoxikologisch charakterisiert. Diese Techniken betreffende, bisherige Forschungsergebnisse beruhen überwiegend auf Experimenten mit Einzelsubstanzen im Labormaßstab während ökotoxikologische Tests und chemische Analytik im Großmaßstab selten sind oder fehlen. Das zentrale Thema dieser Arbeit ist die Bestimmung der Ökotoxizität von Abwasser, das zusätzlich mit Ozon oder Pulveraktivkohle gereinigt wurde. Die zugrundeliegende Hypothese lautet: ‚Die Ökotoxizität von konventionell gereinigtem Abwasser sinkt durch erweiterte Abwasseraufbereitungstechnologien.’ Die Verwendung des Begriffs "konventionelle Abwasserreinigung" bezieht sich hier auf die Reinigungsschritte: Vorklärung (Grobrechen, Sandfang, Fettabscheidung), biologische Reinigung nach dem Belebtschlammverfahren (inkl. Nitrifikation und Denitrifikation) und Nachklärung. Im praktischen Teil dieser Arbeit wurden die Ozonierung an zwei und die Pulveraktivkohlebehandlung an einer Kläranlage parallel zur Ozonierung untersucht. Zu diesem Zweck wurde eine Kombination aus In-vitro- und In-vivo-Tests angewandt sowie natives Abwasser für die In-vivo- und aufkonzentrierte Abwasserextrakte für die In-vitro-Tests verwendet

Comparative toxicity assessment of ozone and activated carbon treated sewage effluents using an in vivo test battery

Wastewater treatment plants do not eliminate micropollutants completely and are thus important point sources for these substances. Ozonation and activated carbon treatment might be beneficial for ecosystem health as these techniques provide effective barriers to organic contaminants. However, a toxicity evaluation is required to investigate toxicity reduction and to assess the potential formation of toxic oxidation byproducts during ozonation.Therefore a comparative toxicity evaluation of different treated wastewater effluents was performed on site at a half scale treatment plant equipped with an ozonation step and an activated carbon treatment step in parallel subsequent to conventional activated sludge treatment. For this purpose four invertebrate and one higher plant toxicity test were selected to assess potential biological effects on whole organisms.The reproduction test with the mudsnail Potamopyrgus antipodarum exhibited a decreased reproductive output after advanced treatment compared to conventional treatment. This indicates an effective estrogenicity removal by ozonation and activated carbon treatment and is confirmed by results of the yeast estrogen screen with a reduction of in vitro estrogenic activity by >75%. The Lumbriculus variegatus test revealed a significantly enhanced toxicity after ozonation compared to conventional treatment whereas this effect was reduced following subsequent sand filtration. When ozonation was applied, a significantly increased genotoxicity was observed, detected with the comet assay using haemolymph of the zebra mussel. Again, this effect was removed by subsequent sand filtration to the level of conventional treatment. Activated carbon treatment even resulted in a significant reduction of genotoxicity.Adverse effects after the ozone reactor are possibly a result of the formation of toxic oxidation byproducts. Biologically active sand filtration obviously is an effective barrier to such compounds

Deriving bio-equivalents from in vitro bioassays: Assessment of existing uncertainties and strategies to improve accuracy and reporting

Bio-equivalents (e.g., 17β-estradiol or dioxin equivalents) are commonly employed to quantify the in vitro effects of complex human or environmental samples. However, there is no generally accepted data analysis strategy for estimating and reporting bio-equivalents. Therefore, the aims of the present study are to 1) identify common mathematical models for the derivation of bio-equivalents from the literature, 2) assess the ability of those models to correctly predict bio-equivalents, and 3) propose measures to reduce uncertainty in their calculation and reporting. We compiled a database of 234 publications that report bio-equivalents. From the database, we extracted 3 data analysis strategies commonly used to estimate bio-equivalents. These models are based on linear or nonlinear interpolation, and the comparison of effect concentrations (ECX). To assess their accuracy, we employed simulated data sets in different scenarios. The results indicate that all models lead to a considerable misestimation of bio-equivalents if certain mathematical assumptions (e.g., goodness of fit, parallelism of dose-response curves) are violated. However, nonlinear interpolation is most suitable to predict bio-equivalents from single-point estimates. Regardless of the model, subsequent linear extrapolation of bio-equivalents generates additional inaccuracy if the prerequisite of parallel dose-response curves is not met. When all these factors are taken into consideration, it becomes clear that data analysis introduces considerable uncertainty in the derived bio-equivalents. To improve accuracy and transparency of bio-equivalents, we propose a novel data analysis strategy and a checklist for reporting Minimum Information about Bio-equivalent ESTimates (MIBEST). © 2013 SETAC

Number of EPT taxa (Ephemeroptera, Plecoptera, Trichoptera) correlating with the first component of the PCA with organic contaminants (OC1).

<p>Displayed are results for sampling campaign in spring (A) and autumn (B). Please note different scaling of y-axes in A and B.</p

Multiple linear regression models testing the effect of environmental parameters and contaminants on biotic response variables: the total number of individuals and taxa, Simpson and Shannon diversity, number of EPT taxa and the saprobic index.

<p>Given are df-, R²-, F- and p-values for full models after stepwise deletion of non-significant terms (n.s.) and of significant model parameters.</p>★<p>, p<0.05;</p>★★<p>, p<0.01;</p>★★★<p>, p<0.001; n.a., not available.</p

Analyzed contaminants.

<p>Analyzed contaminants.</p

River systems with respective streams, abbreviations (abbr.), and number of sampling sites (no.).

<p>River systems with respective streams, abbreviations (abbr.), and number of sampling sites (no.).</p

NMDS biplot of taxa and environmental variables.

<p>Displayed are variables with a significant impact (p<0.05) for sampling campaign in spring (A) and autumn (B). HM, components of the principal component analysis (PCA) with heavy metals; OC, components of the PCA with organic contaminants; structure, structural degradation. Spring: two convergent solutions, two dimensions, stress = 0.17; autumn: two convergent solutions, two dimensions, stress = 0.21).</p