D4.3 – Recommendations on EAOP-CW based treatment system for water reuse applications

The increasing presence of industrial persistent, mobile and toxic compounds (iPM(T)s) and per- and  polyfluoroalkyl substances (PFAS), presents a critical barrier to advancing sustainable water management and the circular economy. To address these challenges, the PROMISCES project, part of the Horizon 2020 Green Deal initiative, aims to develop and demonstrate advanced water treatment technologies integrating electrochemical advanced oxidation processes (EAOP) with constructed wetlands (CW) focuses on reducing the concentration of potentially harmful substances in reclaimed water for agricultural irrigation.
This study contributes to the European Union's goals outlined in the Green Deal, the Zero Pollution Action Plan, and the Circular Economy Action Plan by addressing the removal of persistent contaminants from wastewater to enable safe agricultural irrigation. This initiative is particularly significant for water scarce regions such as Catalonia, Spain. The Besòs case study focused on the Montornès del Vallès Wastewater Treatment Plant (WWTP), where approximately 60% of the incoming wastewater flow comes from industrial sources. The PROMISCES project complies with stringent European and Spanish regulations for wastewater treatment and reuse, addressing the 
demand for advanced systems to adhere to evolving directives, such as the new Urban Wastewater Treatment Directive 2024/3019 and Spanish Royal Decree 1085/2024, approving the EU Water Reuse Regulation (2020/741) in Spain.
This hybrid system combines electrochemical oxidation and ozonation (e-Peroxone or EAOP), generating hydroxyl radicals for the efficient degradation of iPM(T)s and PFAS, while minimizing the energy consumption and reducing the toxic by-product formation. The system also includes a constructed wetland (CW) system, which mimic natural wetlands for pollutant filtration and nutrient absorption. Using plant species such as Phragmites australis and Iris pseudacorus, CWs serve as a post-treatment stage, enhancing effluent quality and providing additional environmental benefits, including promoting biodiversity.
Based on the results, this technological integration tackles the water scarcity challenges commonly faced by Mediterranean regions, positioning reclaimed water as a sustainable and viable solution for agricultural irrigation. Ongoing research and investment in such innovations are essential for driving the advancement of circular water economies.