ReNutriWater: Closing the Water Loop in the Baltic Sea Region

Three Sets of Pilots, One Goal

The project was built around three interconnected pilot phases. The first focused on disinfection — testing technologies such as ozonation, UV radiation, active carbon filtration, and peracetic acid to ensure reclaimed water meets EU Regulation 2020/741 standards for agricultural reuse. Researchers found that all tested methods could reliably meet the highest quality class for reclaimed water, and many treatment steps reduced emerging pollutants such as pharmaceuticals to below detectable levels.

The second pilot tested how the nutrient composition of reclaimed water could be adjusted for practical uses such as irrigating urban green spaces. The third evaluated greenhouse cultivation across four locations, comparing how different plant species responded to reclaimed water of varying compositions.

From Science to Practice

The project developed sustainable business models for wastewater treatment plants, focusing on water, energy, and material streams, and showing how reclaimed water can be economically viable alongside its environmental benefits. A key practical output was the WaterSafe IT tool, which allows municipalities and companies to input wastewater parameters, select a target water quality class, and receive tailored guidance on suitable treatment technologies — simplifying decision-making for those looking to implement water reuse in practice.

A mentoring programme complemented the technical work, helping participating organisations translate project insights into concrete action plans and circular economy strategies.

A Contribution to a Healthier Baltic Sea

By recovering and reusing nutrients such as nitrogen and phosphorus within treated water, the project reduced reliance on artificial fertilisers while curbing nutrient loads entering water bodies — directly addressing the Baltic Sea’s persistent eutrophication challenge. The results align with the EU Strategy for the Baltic Sea Region (EUSBSR) and contribute to SDG 6 on Clean Water and Sanitation.

The project reached its formal conclusion with a final online meeting on 31 March 2026. All project outputs, including guidelines and scientific publications, remain publicly available on the Interreg Baltic Sea Region website, ensuring the knowledge generated continues to support practitioners, municipalities, and policymakers working toward resilient, circular water systems across the Baltic Sea Region and beyond.

Programme Manual Online

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