Constructed wetlands aim to improve wastewater treatment at the output of wastewater treatment plants by using the physical-chemical and ecological mechanisms of aquatic ecosystems. How can their treatment performance be improved? Which processes can be used to eliminate micropollutants? The ZHART research project, launched by SUEZ in 2012 in collaboration with a number of public and private players, aimed to address these questions, and many more.
Ywann Penru, Project Manager within the Wastewater Treatment and Recovery Department at the CIRSEE , and the pilot of the ZHART project, reviews the conduct of the project, which was completed in 2016.
Can you tell us what the ZHART project involved?
Ywann Penru: To begin with, we studied the hydraulic, purificatory and ecological workings of existing constructed wetlands in order to define their particular features according to their size, form, design and performance. The results achieved by a 10 m2 pond are different from those of a 3-hectares area.
Once we had collected this information, we were able to enrich our knowledge and draw a number of conclusions that enable us to choose a particular type of zone according to the objectives, be they educational and/or environmental. In parallel with this analysis of existing zones, the ZHART project looked at the treatment performances of five constructed wetlands in order to carry out specific studies on the removal of emerging pollutants. Thanks to this work, and for the first time ever in France, we are now able to propose constructed wetlands that guarantee the treatment of micropollutants.
How was the project run?
Y.P.: The ZHART project was based on a collaborative initiative. It benefited from the expertise of numerous partners: the RIVE and Nymphea SMEs, the UMR CITERES (inter-disciplinary centre for cities, regions, the environment and societies) at Tours University and the biodiagnostics unit of the LERES (environmental and health research laboratory) of the high school of public health studies (EHESP).
Together, we developed an innovative concept of constructed wetlands that represents a response both to possible regulatory changes and ecological needs, and that guarantees the elimination of micropollutants, while taking into account biodiversity as well as social and territorial considerations. The project developed a methodology that defines the needs according to the territory, and offers a suitable response in cooperation with all the stakeholders (citizens, politicians, NGOs, etc.) to guarantee its success.
How do you view the future of these new constructed wetlands?
Y.P.: Promising! This new constructed wetlands concept is an innovative solution intended for local authorities committed to preserving natural ecosystems and to combating micropollutants in urban waters. There are already plans for further developments, such as a SMART monitoring system, which will optimise the management of these wetlands.