Arising from unique engineering developed by SUEZ, the Dragonfly Zone complements the conventional treatment provided by wastewater plants with the purification capacity of nature. It is an artificial wetland that can be established downstream from a wastewater treatment plant, in which the development of biodiversity intensifies the fight against micropollutants and limits their spread in freshwater or seawater.
The Dragonfly Zone consists of a series of basins of varying shapes and sizes, planted with local species selected specifically for each project (reeds, irises, water mint, sage, rushes, cress, water lilies etc.). The treated wastewater circulating through these basins is purified by a combination of biological actions (biodegradation by microfauna, removal by plants) and physical effects (degradation by the sun, settling). The succession of varying wetland environments, with different flow speeds and depths of water, mobilises these different mechanisms for pollutant degradation or absorption, adapting the treatment to each site's objectives.
Five years of research led by CIRSEE, our main centre of research and expertise, as part of the ZHART project
(2012-2016), led to the Dragonfly Zone concept being finalised. Its scale can be adapted to the treatment goals for the macro- and micropollutants being targeted and to the local context.
Unlike other planted discharge zones, the Dragonfly Zone is able to meet quantified targets
for water regulation, micropollutant treatment
and ecological benefit