A Nature-Inspired Solution: Treatment Wetlands

Treatment wetlands, also known as constructed wetlands, present a nature-inspired approach to wastewater treatment. Embracing the richness of natural processes, these systems hold promise for the challenges posed by tropical and island environments. The three Caribbean nations—Cuba, Dominica, and Saint Lucia—have embarked on a collective endeavor to enhance access to sanitation and safeguard their unique ecosystems through the implementation of treatment wetlands.

Preliminary Studies: Backbone of the Subsequent Construction Phases

Before breaking ground on construction, the partners engage in rigorous preliminary studies. These studies ensure optimal sizing and efficiency in eliminating pollution. The multidisciplinary approach involves several key components:

1. Wastewater Characterization

• Volume Assessment: Determining the volumes of water consumed and discharged by residents.
• Pollution Concentration: Evaluating expected levels of pollution concentration in wastewater.

2. Topographical Studies

• Natural Topography Assessment: Examining whether natural topography supports the flow of wastewater through the treatment wetland or necessitates pumping and transport systems.

3. Soil and Hydrogeological Studies

• Subsurface Water Exploration: Investigating the presence of groundwater and determining excavation limits for construction.

4. Botanical Studies

• Plant Selection: Identifying the most suitable native and non-invasive plant species with underground stems to facilitate efficient infiltration of wastewater and oxygen.

Progress in CARIBSAN partner countries: Cuba, Dominica and Saint Lucia

1. Cuba's Pogolotti Site

• Following wastewater analyses and preliminary studies, precise plans for the Pogolotti site in Havana are taking shape.
• Cuban partners collaborate on a shared research project with institutions from Martinique, Saint Lucia, Dominica, and France1 to explore plants best adapted to the Caribbean context.
• The goal is to test the technology at the Pogolotti pilot site and replicate the model of treatment wetlands elsewhere in the country.

2. Dominica's La Plaine and Cotton Hill Sites

• In Dominica, two pilot sites have been identified: La Plaine site (south-east), whose construction will be financed by CARIBSAN 2, and the Cotton Hill site (north-west), partially supported by the Global Water Partnership - Caribbean.
• Geotechnical, soil, and hydrogeological studies have been conducted, as well as sampling campaigns to characterize wastewater effluents, providing crucial data for the layout of the treatment wetland plant.
  

3. Saint Lucia's Black Bay Vieux-Fort Site

• Saint Lucia plans to upgrade the Black Bay Vieux-Fort site by replacing septic tanks with treatment wetland plants.
• Topographical, hydrogeological, and geotechnical studies are completed, and data on wastewater effluents since 2020 are being translated into the layout of the plant.
  

Towards Phase 2: Finalizing Design and Construction

CARIBSAN's Phase 2 will translate the rich insights from these preliminary studies into the final design and construction of the treatment wetland plants. Simultaneously, the project emphasizes capacity-building and communication to ensure the long-term success and sustainability of these sanitation solutions.
On World Toilet Day, CARIBSAN underscores the commitment to resilient, nature-inspired solutions for the sanitation challenges faced by island nations in the Caribbean. The journey continues, with each step bringing us closer to improved sanitation and a healthier, more sustainable environment for all.

^{1: Conservatoire National Botanique de Martinique, the Ministry of the Environment of Saint Lucia, the Ministry of Agriculture and Forestry of Dominica, the Botanical Garden of Havana, and the French National Institute for Research in Agriculture, Food and the Environment (INRAE)}