On the occasion of the World Day for Biological Diversity, the Société Martiniquaise des Eaux and the Polynésienne des Eaux highlight Nature-Based Solutions2 to preserve and restore our ecosystems in order to “Build a common future for all forms of life”, theme of the 2022 edition of this World Day.
Biodiversity and sanitation: a Purification Solution based on Nature in Martinique
It was in 2014 that the Taupinière wastewater treatment plant was inaugurated by Espace Sud in the town of Diamant in Martinique. It uses a Nature-Based Solution which allows the depollution of the wastewater of some 800 inhabitants of the districts of Taupinière, Fond Manoël, O’Mullane Haut and Bas.
The technology of filters planted with plants3 is a fine example of partnership with nature in direct connection with a daily human activity: wastewater treatment.
The technology of the Taupinière wastewater treatment plant or that of Mansarde Rancée at François, relies on the natural action of plants (here birds of paradise) to ensure the different stages of wastewater treatment, in particular the bacteria oxygenation. The Taupinière station, in its depollution process by dumping on 4 beds planted with macrophytes, thus contributes to the preservation of the ecosystem.
The transformation and absorption of pollutants take place in the soil, through the action of a wide variety of bacteria that treat both wastewater and suspended solids.
Plants, through the action of their roots, essentially play a mechanical role, and promote gas exchange between the soil and the air.
On a visit to Martinique with a team of inspectors on the occasion of a technical mission and a seminar which brings together all the agents of the OFB in the West Indies and Guyana, Odile Cruz, head of the support for actors, knowledge and mobilization of Territories at the OFB explains: “The OFB is very concerned about the preservation of natural environments and biodiversity. This treatment alternative is for us a preferred system for small stations. Firstly because the results are very convincing and the quality and technicality of operation are much easier than on more sophisticated systems of the activated mud type. We have a sanitation system that is based on a Nature-Based Solution with plants that will be used for purification, with a
rejection quality which will be completely adapted to the sensitivity of the receiving environment”.
The Société Martiniquaise des Eaux, which has been operating the two stations with filters planted with plants for four years – properties of the Espace Sud – confirms the ecological, economic and also technical interest of this technique of “filters planted with plants”.
In Bora Bora, rhizomes treat wastewater from the “Pearl of the Pacific”
In the Pacific, Moanatea Leu, Vaitehi – Polynésienne des Eaux operations manager in Bora Bora (French Polynesia) uses another Nature-Based Solution for the purification of wastewater from the “Pearl of the Pacific”: “Originally, wastewater was treated in a lagoon. In 1997, in order to increase treatment capacity, the Povai lagoon was transformed into an activated sludge treatment plant. With this process change, it was necessary to manage the continuous production of sludge. This is where rhizomes come in. Rhizomes are part of the reed family. They were implanted in the sludge drying beds at that time. The primary benefit of using reeds in drying beds centers on their ability to create a dense root network. They contribute
thus to the aeration of the sludge, to a better drainage of the water and to prevent the sludge from rotting in the drying beds. Odors are also avoided thanks to the rhizomes.
Another advantage of rhizomes: absorbing, while developing, part of the pollution contained in the sludge. This sludge is then recycled for composting. On average, 36 tons of sludge are extracted annually at the Povai wastewater treatment plant”.