Coordinators:

UR REVERSAAL:

Contact:

Pascal MOLLE – pascal.molle(at)inrae.fr

Stéphanie PROST-BOUCLE –  stephanie.prost-boucle(at)inrae.fr

Active period:

2025-2027

Financing:

French Office of Biodiversity (OFB): 60%
INRAE: 40%

Partners:

None

Background:

The development of wastewater treatment in the French overseas territories (Martinique, Mayotte, Guadeloupe, Guyane, and La Réunion) has been the focus of a research partnership between the French Office of Biodiversity and INRAE REVERSAAL since 2008. The work carried out as part of this research initiative has enabled the French vertical flow treatment wetland system to be adapted to the tropical context. The deliverables produced are available (in French only) on the Epnac website in the Overseas section (https://www.epnac.fr/outre-mer):

• LOMBARD-LATUNE, R., & MOLLE, P. (2015). Quelles plantes pour les filtres plantés de végétaux dans les DOM ? (p. 76 pages) [Rapport final projet ATTENTIVE]. IRSTEA et Office National de l’Eau et des Milieux Aquatiques.

• LOMBARD-LATUNE, R., & MOLLE, P. (2017). Les filtres plantés de végétaux pour le traitement des eaux usées domestiques en milieu tropical (Guide de dimensionnement de la filière tropicalisée) (Guides et protocoles, p. 72 pages). Agence française de la biodiversité.

ROSSE, M.-C., LEBRET, C., LACOMBE, G., & MOLLE, P. (2022). Traitement des eaux usées à l’échelle individuelle par FPV en milieu tropical : Retour d’expérience en Guyane (p. 51 pages).

In collaboration with local actors (Water offices, DREAL Mayotte), new research priorities have been identified for 2022 onwards. These priorities aim to support small and medium-sized local authorities in developing urban water management strategies (wastewater and stormwater) that are more relevant to local issues.

The three-year period 2022-2024 has made it possible to achieve the following objectives:

• Initiate the development and achieve a beta version of ELAN, a GIS tool to help decision-making on the centralization/decentralization of sanitation. For more information, visit the project page.
•  Explore the issue of decentralized stormwater management through nature-based solutions in the study areas: https://hal.inrae.fr/hal-05163428v1/document (French only).
• Instrument and initiate monitoring of a site where stormwater is managed at source by infiltration on the territory of La Réunion (study in progress).
• Carry out an inventory of sludge and wastewater disposal methods common to the five territories: https://hal.inrae.fr/hal-04910047v1/document (French only).

Objectives:

The three-year period 2025 - 2027 is a continuation of the previous one, with the following objectives:

• Continue the development of ELAN, a QGIS extension for decision support on the issue of centralization/decentralization, aimed at public and private stakeholders in the sanitation sector.
• Monitor the site instrumented at La Réunion for stormwater infiltration, in order to provide initial feedback after 2 years of data acquisition, as well as recommendations in terms of sizing.
•  Instrument and monitor the first sludge treatment wetland with vegetation commissioned in one of the study areas (Marie-Galante, Guadeloupe), and draw up feedback to specify the sizing and management rules for this process (for activated sludge and sewage) in a tropical context.

Organization:

The project is coordinated by Pascal Molle and Stéphanie Prost-Boucle. It is structured along three axes, led by researchers from REVERSAAL:

1 - ELAN tool: Nicolas Forquet.

2 - Decentralized Stormwater management: Rémi Clément.

3 - Sludge treatment: Stéphanie Prost-Boucle.

It relies on local relays: OFB delegations, Water Offices, DEALM in Mayotte, inter-municipalities. A full-time research engineer is working on this project: Gabrielle Favreau.

Anticipated benefits:

• Appropriation by local actors of the GIS tool developed and of the issues involved in decentralization.
• A better understanding of how decentralized stormwater management solutions work in a tropical context.
• Identification of possible adaptations of decentralized stormwater management solutions to the tropical context.
• Mobilization of local players on the subject of decentralized stormwater management.
• Provide insight on the sizing and performance of sludge treatment wetlands for the treatment of sewage sludge.