SUEZ (Paris) announced the inauguration of the Eaux Blanches wastewater treatment plant in Sète, France. The new plant treats 89% of the wastewater from seven municipalities of Sète agglopôle méditerranée – representing 6.5 million m3 of wastewater treated per year, equivalent to 165,000 inhabitants, with a capacity that can be extended to 190,000 population equivalent.
The Eaux Blanches wastewater treatment plant uses ultrafiltration membrane technology to treat wastewater. It meets the strictest regulatory requirements and removes over 90% of organic pollution to achieve “Class A” or “bathing water” quality discharge, thereby preserving the Mediterranean Sea and the Thau Basin, a sensitive ecosystem located near the plant.
The plant is equipped with a storm basin to store excess wastewater during rainy periods and a differentiated operating system that adapts to high rainfall. These devices are designed to minimize overflow risk and optimize the quality of wastewater released into the natural environment. These innovative processes contribute to the preservation of aquatic environments and local economic activities, particularly shellfish farming, which is essential to the region.
The Eaux Blanches wastewater treatment plant produces both reusable wastewater and renewable energy for local use. Located within the Val’Thau ecopole, the plant is connected to the neighboring waste-to-energy plant and the industrial company SAIPOL to optimize water, energy and material flows. This collective governance, led by Sète agglopôle méditerranée, contributes to the region’s water and energy resilience.
The plant recovers sludge from wastewater treatment to produce 500,000 Nm³ of biomethane per year, which is fed back into the GRDF network. It also recovers 2,800 MWh of steam from the waste-to-energy plant to dry the sludge. From 2025, this steam will be used to heat the digester, thereby improving the performance of the methanization process. The residual sludge is then composted and used in local agriculture, thus closing the recovery chain.
Additionally, a Treated Wastewater Reuse unit helps preserve drinking water resources. Currently, more than 60,000 m³ of treated water per year is used by the waste-to-energy plant. Starting in 2026, an additional 540,000 m³ per year will be used for SAIPOL’s industrial activities. These strictly regulated initiatives address climate and water issues while supporting the region’s strategic activities.
The new Eaux Blanches wastewater treatment plant is a model of innovation by Sète agglopôle méditerranée to tackle the challenges of preserving resources and sensitive natural environments while promoting regional development. In 2018, the local authority launched a project to modernize the sanitation infrastructure and build a new plant. This major project led by Sète agglopôle méditerranée, the Rhône Méditerranée Corse Water Agency and Thau Maritima (a project company created by SUEZ and the investment company Vauban Infrastructure Partners), represents an investment of more than €64 million.
“We have chosen a plant with high environmental and territorial added value. The Eaux Blanches wastewater treatment plant is an investment that perfectly meets our needs and will shape the future of the regionm,” said Loïc Linares, President of Sète agglopôle méditerranée.
“The Eaux Blanches wastewater treatment plant demonstrates the ability of local authorities to address the challenges of water transition, aquatic environment preservation and climate change adaptation. It is a concrete response resulting in facilities that are simple, smart and integrated,” said Karine Bonacina, Director of the Montpellier delegation of the Rhône Méditerranée Corse Water Agency.