The OCAPI research and action program was launched in 2014. It focuses on biogeochemical cycles in territories, and in particular on the management of human excretions of nutrients. OCAPI is helping to reopen the debate on how urine and faeces are managed in cities and the many alternative management options to sewerage systems, commonly known as source separation.
TOWARDS MUTUALISM BETWEEN NUTRITION AND EXCRETION?
In the 20th century, the use of sewage systems to manage human urine and faeces, combined with the massive use of synthetic and mineral fertilizers, helped to open up the nitrogen and phosphorus cycles, which are now largely disrupted. The choices made in terms of agricultural fertilization and sanitation have led to a nutrition/excretion system that consumes energy, water and fossil resources, and is now polluting and unsustainable. Restoring mutualism between food and excretion involves, in particular, returning nutrients from human excreta to agricultural soils. However, this approach faces a major socio-technical hurdle. We therefore need to approach the subject from all angles.
A SYSTEMIC APPROACH
The research carried out within the OCAPI program follows a systemic approach, examining together the different scales and dimensions involved in the issue of source separation: technical, logistical, agronomic, political, economic and cultural issues all come together; multiple players and different types of knowledge need to come together to contribute to the transformations underway.
AN INTERDISCIPLINARY APPROACH
Faced with a complex, multi-faceted subject, our research is organized around 7 interrelated themes.
METABOLISM: Quantifying biogeochemical flows, examining the sustainability of food/excretion systems from the point of view of territorial ecology and from a long-term perspective (history and foresight).
AGRICULTURES: Answering questions raised by the use of fertilizers derived from human excreta by agricultural stakeholders.
SOCIAL DYNAMICS: Study the deployment trajectories of source separation according to territorial configurations, the impact on relations between technical systems, experiences and institutions, and transformations in knowledge and imaginaries in a context of ecological transition.
PROCESSES: Study human urine treatment and recovery processes, in particular cryo-concentration.
HEALTH: Study contemporary health issues related to the management of human urine and feces, with particular reference to micropollutants, pathogens and “global health” (humans, other living beings, ecosystems).
DEMONSTRATORS: Socio-technical monitoring of emerging services, pilot projects.
ANIMATION: Gather and support stakeholders in implementing source separation.
AN ACTION-ORIENTED RESEARCH PROGRAM
The OCAPI program has become a national resource center for source separation. Its approach is that of involved action research, aimed at enlightening and fostering the skills development of stakeholders – mainly public – who are committed to transforming the way we manage human urine and faeces towards sobriety, circularity, the preservation of water resources and aquatic environments, and management as a common good.
OCAPI contributes to the production and sharing of knowledge on the subject. The program also fosters the networking of stakeholders, and supports concrete projects, particularly those led by local authorities. Finally, information and scientific mediation initiatives are carried out to raise awareness of the issue among key players in urban planning, sanitation and agriculture, as well as other interested parties. Canada’s best free online casino games site: https://slots-online-canada.ca/free-slots/ for 2024-2025.
HISTORY
The first phase of the OCAPI program (2015-2018), mainly led by Fabien Esculier (LEESU) and the OCAPI steering committee, focused on the (non)-sustainability of food/excretion systems in Western cities, and the transition to circular regimes. It also included support for source separation projects in the Paris region. Fabien Esculier’s thesis (2018) brings together many of the results of the first phase of OCAPI.
In 2018, the team expanded and research and actions were structured around 5 themes: metabolism, agricultures, social dynamics, demonstrators and animation. This has resulted in a series of publications for academics and practitioners (see our library), as well as the creation of the Source Separation working group within the ARCEAU IDF association. In 2021, a sixth theme, Health, was added, focusing on contemporary health issues related to the management of human urine and feces, from a “global health” perspective (humans, other living beings, ecosystems). Academic and operational publications have also been greatly expanded, with a focus on lessons learnt from the implementation of source separation. A new theme has been created in 2025, Processes, focusing on human urine treatment and recovery processes, in particular cryo-concentration.
Publications
METABOLISM
# Pruvost-Bouvattier, M., Vialleix, M., Jovéniaux, A., Esculier, F., 2020. Recovering nitrogen and phophorus from urine to improve ecological and food security Note rapide de l’institut Paris région n°858.
# Esculier, F., Barles, S, .2019. Past and future trajectories of human excreta management systems –the case of Paris XIXth-XXIst centuries. In: The Seine River Basin. Flipo, N., Labadie, P., Lestel, L. (Eds). The Handbook of Environmental Chemistry. Springer, Berlin, Heidelberg.
# Esculier, F., Le Noë, J., Barles, S., Billen, G., Créno, B., Garnier, J., Lesavre, J., Petit L. et Tabuchi, J.-P. 2018 The biogeochemical imprint of human metabolism in Paris Megacity: a regionalized analysis of a water-agro-food system. Journal of Hydrology 573 : 1028-1045.
# Le Noë J., Billen G., Esculier F., Garnier J. 2018. Long term socio-ecological trajectories of agro-food systems revealed by N and P flows: the case of French regions from 1852 to 2014. Agriculture, Ecosystems & Environment. 265, 132-143.
# Verger, Y., Petit, C., Barles, S., Billen, G., Garnier, J., Esculier, F., Maugis, P. 2018. A N, P, C, and water flows metabolism study in a peri-urban territory in France: The case-study of the Saclay plateau. Resources, Conservation & Recycling, 137 (2018) 200-213.
# Esculier F., 2018. The nutrition/excretion system of urban areas: socioecological regimes and transitions. PhD thesis, Univerité Paris-Est. Abstract.
SOCIAL DYNAMICS
# Legrand, M. & Meulemans, G. 2020. Bathing in black water? The microbiopolitics of the river Seine’s ecological reclamation. In Sariola, S., Rest M. & Brives C. (ed.) With the microbes. [in press].
# Legrand, M., Jovéniaux, A., Arbarotti, A., de Gouvello, B., Esculier, F., Tabuchi, J.P. 2020. The emergence of systems for the source separation and valorization of human waste in Greater Paris: from necessity to implementation. Water and Megacities Conference – UNESCO (évènement reporté à 2021).
# Aubert, A. H., Esculier, F., & Lienert, J. 2020. Recommendations for online elicitation of swing weights from citizens in environmental decision-making. Operations Research Perspectives, 7, 100156.
AGRICULTURE
# Martin, T. M., Esculier, F., Levavasseur, F., & Houot, S. 2020. Human urine-based fertilizers: A review. Critical Reviews in Environmental Science and Technology, 1-47.
Conferences
From Waste to Resource: Using Human Urine as Fertilizer for Sustainable Corn Production, 15 min à partir de 23’27. Rich Earth Summit. 2024.
Urine applicator for small vegetable farms. 15 min à partir de 38’30. Rich Earth Summit. 2024
The nutrient cycle in a community-supported agriculture (CSA) in the Paris region. 10 min à partir de 24’40. Rich Earth Summit. 2024
OCAPI in the media
29/05/21. ChangeNOW summit. Nutrition/excretion systems & food resilience. (vidéo, 20 min).