Can wastewater treatment plants (WWTPs) contribute to the production of green hydrogen? To answer this question, the consortium formed by the Institute of Photonic Sciences (ICFO), Apria Systems and Sorigué is investigating the effectiveness of electrolysis with water that is not 100% purified, as is the case with water from a WWTP. 

The project, named RES2H2, is funded by the NextGenerationEU recovery plan for Europe under the PERTE for Renewable Energies, Renewable Hydrogen and Storage. For its development, it relies on ICFO’s knowledge in photonics and electrolysers, Apria’s engineering work in electrolysis systems, and Sorigué’s experience in wastewater treatment. 

Between May and December 2026, the RES2H2 pilot plant operates in the real environment of the Montornès del Vallès WWTP, under the supervision and control of the Department of Innovation at Sorigué, which is responsible for deploying R&D&I projects that can be applied to the business. 

What is the main innovation of RES2H2? 

The most innovative aspect of the project is the use of an unusual resource, treated wastewater from a treatment plant, in combination with an emerging technology, the anion exchange membrane electrolyser (AEM). 

Typically, conventional electrolysers use highly purified and deionised water to obtain hydrogen, but in this case, a more sustainable, efficient and accessible production model is proposed, without the need for advanced water purification.  

Why is it important to work with the AEM electrolyser? 

Currently, AEM is one of the most promising technologies for green hydrogen production, as it combines the best of the high efficiency of PEM (proton exchange membrane) systems with the low costs of alkaline electrolysers that use non-precious metal catalysts such as nickel.

What does the RES2H2 project pilot test consist of? 

The RES2H2 project pilot test will take place at the Montornès del Vallès wastewater treatment plant, one of the largest sewerage systems in the Besòs river basin, Catalonia, with a daily flow of 40,000 m³. 

The pilot plant will process a flow rate of 1.2 m³/h through pretreatment and its subsequent passage through a 6 kW AEM electrolyser. Thus, the research seeks to contribute to the promotion of H₂ generation systems from wastewater and, at the same time, to the elimination of pollutants and pathogens through oxidative processes. 

Sorigué will carry out various tests to evaluate the technical viability of the procedure in a real environment with flows from rural, urban, industrial and agricultural settings. 

Should the RES2H2 project be successful, what applications could it have? 

Currently, water from treatment plants is used to irrigate fields or wash down streets, among other applications, so, if its usefulness as a source of green hydrogen is proven, it could represent a pioneering solution for decentralising the production of this clean fuel. 

With over 70 years of experience, Sorigué participates in innovation projects with European impact that seek sustainable solutions and can add value to its activity. 

Currently, and particularly in the water sector, the company is part of the Solucir project, which seeks much more resilient and flexible urban cycle management models; the Asterisk project for hydrogen production with seawater, and Life Biodaph20 to test a tertiary wastewater treatment system using microcrustaceans, among other research projects.