On 22 April 2026, the city of Salamanca hosted the 1st Community of Practice on Circular Cities, held at the International Spanish Centre of the University of Salamanca within the framework of the European Horizon Europe project UNITED CIRCLES.

This international event brought together representatives from public administrations, companies, research organisations and other key stakeholders to share success stories and foster synergies in the circular economy, with a particular focus on transforming waste and by‑products into valuable resources. The meeting highlighted the strong potential of urban‑industrial symbiosis as a driver to optimise the use of materials, energy and water, minimise waste and emissions, and advance towards more sustainable cities and regions.

The event was opened by Carlos García Carbayo, Mayor of Salamanca, together with Ángel Luis Pérez Buitrago, Director of Aqualia’s Central Region Delegation, who underlined the city’s strong commitment to innovation and circularity. This was followed by presentations on local and European initiatives, including the circular actions being implemented in Salamanca and the vision of the UNITED CIRCLES project, aimed at identifying symbiosis opportunities, connecting stakeholders and developing new circular business models.

The agenda featured inspiring contributions, such as that of Theresa Zabell, a two-time Olympic champion and a pioneer in marine environmental protection, alongside technical presentations and practical case studies from project partners within the Salamanca Hub. Concrete solutions were addressed in key areas such as the integrated water cycle, waste valorisation, nutrient recovery, the social economy, and circularity in industrial sectors including paper, fertilisers, food and biosolids management. International experiences were also showcased, including the Danish BIOFOS model.

During the session dedicated to invited cities and projects, the role of municipalities, cooperatives and territorial initiatives as drivers of the circular transition was highlighted, emphasising the importance of adapting solutions to local contexts and promoting public‑private collaboration.

The day concluded with a visit to the Innovation Centre for the Integrated Water Cycle at the Salamanca WWTP, where participants were able to learn first‑hand about the Ecofactory concept and its practical application in closing water, energy and resource loops, key elements within the UNITED CIRCLES project. From UNITED CIRCLES, we would like to thank all organisations and professionals for their active participation and valuable contributions to the success of this Community of Practice. The event reinforces the project’s role as a European platform for knowledge exchange and the co‑creation of solutions towards a more circular, resilient and sustainable future.