The European Horizon 2020 ULTIMATE promoted circular economy concepts withinthe framework of water smart industrial symbioses. It focused on industrial wastewaterstreams as resource for water, energy and material recovery. ULTIMATE, in nine casestudies, developed and demonstrated 24 circular economy related technologies. Inseven out of the nine case studies, a total of eleven water-related technologies wereinvestigated. D1.3 focuses on wastewater treatment and reuse technologies in various Europeanregions and contributes to building a circular water economy. By promoting efficientwastewater management and reducing reliance on freshwater resources, it supportsindustries, and agriculture in some cases, while preserving natural ecosystems. Most of the lessons learned outlined in this document focus on the more technical andscientific aspects of the proposed technologies in the various case studies, althougheconomic and regulatory aspects are also discussed. This is why the findingspresented in this report also aim to contribute to shape policies, drive innovation, andfoster cooperation, ultimately promoting sustainable practices that benefit both theenvironment and the economy across Europe.