the dragonfly zone (zone libellule)

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The fight against the presence of emerging substances (pesticides, medication etc) and their derivatives which degrade water quality represents a veritable stake which is clearly reflected in regulatory evolutions.

In effect, the European Union imposes that new pollutants (endocrine disruptors, pharmaceutical residues, hazardous substances…) must disappear from our water within the next 20 years.

Currently, only between 30 and 80% of micro-pollutant flows, depending on substances, are stopped by treatment facilities.

These molecules appear in environments at an exponential rate and can disrupt elements from the trophic chain via accumulation or synergy, whilst we can detect them in water at very low concentrations which are often below detection limits.

Whilst absorption treatments using activated carbon and ozone oxidation provide a treatment solution, other disposal routes must be developed, namely for smaller facilities.

Among them, we can mention the Artificial Wet Zones (Zones Humides Artificielles).
The natural diversity of wet zones (biofilms, diatoms, plancton, microphytes, macrophytes, fauna..) and root symbioses provide a wealth of complementarity to biological processes and standard treatment systems.

All of these reactions consequently ensure more refined water treatment. To resolve the problems of micro-pollutants, SUEZ has developed a new wet zone concept known as the Dragonfly Zone.

The Dragonfly Zone is an artificial wet area able to be placed downstream of the wastewater treatment plant and in which the development of biodiversity contributes towards combatting micro-pollutants, limiting their diffusion into fresh or salt water sources.

The various successive zones (which among others include basins, phytoplancton, reed beds, damp pastures…), based on the purification capacities of various aquatic eco-systems, are planted with locally selected plants. Thanks to a complex hydraulic run-off, the Dragonfly Zone protects the receiving environment whilst generating a better quality water at both a chemical and a bacteriological level.

Faunal and plant dynamics also permit a particularly rich educational and recreational biodiversity support to be developed.

The surface area of these wet zones can range from several hundred m2 to several hectares depending on the flow reduction and local biodiversity development objectives.