This report summarizes the current situation on End-of-waste (EoW) applications and procedures for circular products from water. Based on a review of reports, stakeholder interviews and workshops, it describes status and challenges of different routes to achieve EoW status for water-related products. EU-wide harmonisation of related EoW criteria has a low political priority, mainly due to low-volume products and niche markets addressed. However, there are on-going initiatives and enabling political frameworks that could facilitate EoW applications for new products from the water sector. Next steps are proposed to overcome the existing bottlenecks for successful EoW applications.

The use of activated sludge models (ASMs) is a common way in the field of wastewater engineering in terms of plant design, development, optimization, and testing of stand-alone treatment plants. The focus of this study was the development of a joint control system (JCS) for a municipal wastewater treatment plant (mWWTP) and an upstream industrial wastewater treatment plant (iWWTP) to create synergies for saving aeration energy. Therefore, an ASM3 + BioP model of the mWWTP was developed to test different scenarios and to find the best set-points for the novel JCS. A predictive equation for the total nitrogen load (TN) coming from the iWWTP was developed based on real-time data. The predictive TN equation together with an optimized aeration strategy, based on the modelling results, was implemented as JCS. First results of the implementation of the JCS in the real environment showed an increase in energy efficiency for TN removal.

Potenziale einer Substitution von Trinkwasser durch andere Wässer wurden für Frankfurt am Main in einer fachübergreifenden Studie mit Hilfe von Sekundärdaten und Szenariobetrachtungen abgeschätzt. Für das Stadtgebiet insgesamt sind sie erst langfristig und mit politischer Anstrengung umfassend realisierbar. Die Verwendung von Betriebswasser könnte ab 2050 nennenswert dazu beitragen, den Aufwand bei der Produktion von Trinkwasser zu reduzieren. Kosten- und CO2-Bilanzen verdeutlichen, dass der höhere Ressourcen- und Energieaufwand für Bau und Betrieb stark von örtlichen Voraussetzungen abhängt.