Upgrading wastewater treatment plants (WWTPs) with advanced technologies is one key strategy to reduce micropollutant emissions. Given the complex chemical composition of wastewater, toxicity removal is an integral parameter to assess the performance of WWTPs. Thus, the goal of this systematic review is to evaluate how effectively ozonation and activated carbon remove in vitro and in vivo toxicity. Out of 2464 publications, we extracted 46 relevant studies conducted at 22 pilot or full-scale WWTPs. We performed a quantitative and qualitative evaluation of in vitro (100 assays) and in vivo data (20 species), respectively. Data is more abundant on ozonation (573 data points) than on an activated carbon treatment (162 data points), and certain in vitro end points (especially estrogenicity) and in vivo models (e.g., daphnids) dominate. The literature shows that while a conventional treatment effectively reduces toxicity, residual effects in the effluents may represent a risk to the receiving ecosystem on the basis of effect-based trigger values. In general, an upgrade to ozonation or activated carbon treatment will significantly increase toxicity removal with similar performance. Nevertheless, ozonation generates toxic transformation products that can be removed by a post-treatment. By assessing the growing body of effect-based studies, we identify sensitive and underrepresented end points and species and provide guidance for future research.

Im Rahmen des Forschungsvorhabens „Phorwärts“ wurde auf Basis aktuell erhobener Daten die konventionelle Phosphatdüngemittelherstellung (vom Abbau des Phosphaterzes in der Mine bis zur Anwendung auf dem Feld) mit ausgewählten Verfahren der P-Rückgewinnung aus dem Abwasserpfad ökobilanziell verglichen. Die verschiedenen Düngemittel wurden hinsichtlich ihrer Kontaminationen wie den Schwermetallen, den organischen Schadstoffen und den Pharmaka-Rückständen zusätzlich in einer vergleichenden Risikobewertung der Düngemittelanwendung für die Wirkungspfade Bodenorganismen, Grundwasser und im Hinblick auf die menschliche Gesundheit untersucht. Eine Kostenschätzung der verschiedenen Produktionswege komplettiert den Vergleich der konventionellen Phosphatdüngemittelproduktion mit der Produktion von Recyclingdüngern aus der Kläranlage. Die Ergebnisse der Studie zeigen, dass eine technische Phosphatrückgewinnung aus dem Abwasserpfad unter bestimmten Bedingungen ökologisch und wirtschaftlich sinnvoll ist. Neben dem eigentlichen Phosphatrückgewinnungsverfahren sind in hohem Maße die lokalen Randbedingungen bezüglich der Ergebnisse der vergleichenden Bewertung entscheidend. Unter Berücksichtigung der kommenden gesetzlichen Randbedingungen der Dünge- und der Klärschlammverordnung wird in Zukunft voraussichtlich die Monoverbrennung als primäre Option für die Klärschlammentsorgung dienen und die Phosphatrückgewinnung vorwiegend aus der Klärschlammasche erfolgen. Da bei der Rückgewinnung aus der Klärschlammasche hohe Rückgewinnungsraten, die den Vorgaben der Klärschlammverordnung genügen, erzielt werden können, ist ab dem Kalenderjahr 2029 mit etwa 30.000 bis 40.000 Tonnen Phosphor pro Jahr in Form von Phosphatrezyklaten zu rechnen. Inwieweit und zu welchen Preisen diese Rezyklate durch den Markt angenommen werden, kann aus heutiger Sicht noch nicht abgeschätzt werden.

The focus of this study investigation was laid on the plant-specific applicability of a NaOH and thermal pretreatment of activated sludge AS with following mesophilic digestion and the influence on the biomethane potential BMP. Firstly, the hydrolysis of activated sludge from the granular sludge process of the Nereda technology, which differs from conventional activated sludge in terms of sludge formation, sludge stabilization, and sludge age, was investigated for the first time. A higher dose of NaOH (0.02 - 0.08 g NaOH per gVS, 70 °C) raised the COD and phosphate degree of digestion and the digester gas yield by 22 - 47 %. Different hydrolysis temperatures (50 - 90 °C, 0.05 g NaOH per gVS) also increased the sludge parameters. However, the BMP only enhanced by 12 % at temperatures higher than 70 °C. With increasing hydrolysis temperature, the digestion time was reduced by 2 - 5 days. Despite the process-related differences between conventional AS (from the Stahnsdorf wastewater treatment plant) and AS from the granular sludge processing, comparable results were obtained in the BMP test, with and without pretreatment. Due to a lack of time, the experiments could only be carried out once or twice. As there are currently no further experience and references on this subject, additional attempts for achieving significant results will follow. In the second part, sludges from the Waßmannsdorf sewage treatment plant were used. Laboratory tests have shown that primary sludge has no influence on the digestion process. The calculated BMP of 176.5 NmL/gCSB deviates by 3% from the value of 181.9 NmL/gCSB measured in the laboratory test. It is directly related to the ratio of the used sludges. Hydrolysis according to PONDUS (70 °C; 2 h; 2.5 mL NaOH 50 % per L AS) at laboratory revealed a comparable influence on the sludge parameters as with hydrolysis on a pilot scale. During the BMP test, the laboratory sample achieved a maximum gas yield of 143 NmL/gCSB, which is a 9 % higher BMP in comparison to the pilot sample with 132 NmL/gCSB. The laboratory results can, therefore, be transferred to the pilot scale, so that the effects of changes in operation can be reliably assessed by cost, time and effort saving laboratory tests. This thesis was written within the framework of the project “Evaluation of process options for the reduction of energy consumption and greenhouse gas emissions of Berlin sewage treatment plants" at the Berlin Centre of Competence for Water.

This paper presents the assessment of a planned scheme of indirect potable reuse (IPR) in the Vende´e region of France in its potential risks for human health and ecosystems, and also in its overall environmental impacts. Methods of risk assessment (quantitative microbial and chemical risk assessment) and life cycle assessment (LCA) are used to characterize the risk associated with the use of reclaimed water for IPR, but also the environmental benefits compared with other options for additional drinking water supply. The LCA results show that IPR is competitive with other options of water supply in its energy demand and greenhouse gas emissions. Pathogens as the main health hazard are controlled effectively by existing and planned preventive measures. For chemicals the number of potentially relevant substances could be reduced substantially by the assessment.

Objectives: (i) To ensure that knowledge developed during the project is properly captured and dissemination is effectively targeted and carried out systematically (ii) To promote a continuous knowledge exchange and transfer for project outcomes with interested stakeholders beyond the consortium (iii) To formulate fact based policy recommendations that stimulate the transition towards a circular economy (iv) To create public awareness concerning the need for a circular economy and the actions required to move towards its realisation