Years : 2024 - 2027

Name of the project : FreezePee : Evaluation of an innovative cryoconcentration process: development, analysis and demonstration of a new urine-based fertilizer.

Funding: APR GRAINE de l’ADEME.

1. Context and proposal

In the current wastewater management model ("everything down the drain"), most urban effluents are collected and directed to treatment plants where they are processed. This approach is predominantly linear, with nitrogen primarily denitrified and released into the atmosphere, and with only 4% being recycled in the Île-de-France region, even though the excretions of its residents could cover the region’s fertilizer needs. Urine has the advantage of containing most of the excreted nutrients. Moreover, it is generally low in pathogenic and metal contamination, although the question of pharmaceutical contaminants remains. Various treatments can be applied to urine to produce different urine-based fertilizers.

The Agrocapi project (APR Graine 2018) demonstrated the strong potential of urine-based fertilizers to increase agricultural resilience and reduce its environmental footprint. Building on Agrocapi’s findings, the FreezePee project aims to establish a new inventory of existing and emerging urine valorization pathways in agriculture and evaluate them.

Ultimately, in alignment with the OCAPI research-action program, this project seeks to support the emergence of the most relevant human urine valorization pathways tailored to different territorial contexts. Positioned at the intersection of multiple disciplines (agronomy, environmental science, process engineering, etc.), this project brings together multidisciplinary and complementary research teams along with non-scientific partners.

2. Objectives

A comprehensive literature review compiling current knowledge will be conducted and supplemented by an evaluation of emerging pathways. Particular attention will be given to the three major challenges highlighted in the Agrocapi project: achieving low-energy urine concentration, minimizing nitrogen volatilization, and improving understanding of the fate of organic micropollutants.

Experiments will be conducted on recent advancements in nutrient concentration through freezing, new nitrogen stabilization methods (acidification, passive nitrification), and the fate of micropollutants. The anticipated new urine-based fertilizers include acidified granulated urine ("granurin") and fertilizers derived from freezing processes (some of which will be produced ad hoc following passive nitrification). These products will be characterized (nutrient concentrations, composition, pharmaceutical residues), particularly through field trials (agronomic interest, ammoniacal nitrogen volatilization). Their production chains will also be analyzed (energy and water consumption, avoided pollution, etc.).

Finally, the project aims to promote the dissemination of alternative solutions by showcasing its results through the creation of a pedagogical demonstrator, highlighting the challenges and solutions available and presenting the pathways studied within this project.

Partners

• Université Paris-Est Créteil - LEESU
• Ecole Nationale des Ponts et Chaussées - LEESU
• INRAE - UMR ECOSYS
• Terre et Cité
• Chambre d’Agriculture de Région Ile-de-France

Contacts: Julien Le Roux, Corentin Eschenbrenner, Fabien Esculier