Switzerland: Stereau at the forefront of the fight against micropollutants


Interior view of the Penthaz wastewater treatment plant (Switzerland)

In 2006, the FOEN (Swiss Federal Office for the Environment) launched the “MicroPoll Strategy” project to explore techniques for eliminating micropollutants from wastewater. In 2016, the revision of the Water Protection Act came into force forcing certain wastewater treatment plants to improve their efficiency in treating these molecules. Since 2018, Saur and its subsidiary Stereau have been effectively supporting Swiss wastewater treatment plants in improving their performance with the patented CarboPlus® process.

The treatment obligation applies not only to large treatment plants, but also to smaller ones discharging into a body of water used as a source of drinking water or for fishing and recreation. In all, almost a hundred of the 700 wastewater treatment plants in Switzerland must comply with the standard. The Swiss law aims for an 80% reduction in a dozen molecules, mainly drug residues.

Commissioned in 2018, the CarboPlus® at the Penthaz wastewater treatment plant (324 m3/h) is the first to be installed. The performance and reliability of the process have given rise to other projects:

  • Delémont – 1,940 m3/h: operational since 2022.
  • Yverdon-les-Bains – 1,764 m3/h, in progress.
  • Rosenbergsau – 2,448 m3/h, under construction.
  • Villette – 4,140 m3/h: currently under construction, this facility will treat water from 12 communes in the Canton of Geneva, as well as effluent from the Annemasse Agglo wastewater treatment plant. A great example of cross-border cooperation!

Five plants will soon be equipped with the CarboPlus® process.

On the other side of the Alps and in France, Stereau and the Saur group have deployed over 20 CarboPlus® installations, to meet the health and ecological treatment objectives of wastewater treatment plants, drinking water plants and industrial plants.

"CarboPlus® soutient les stations d'épuration suisses dans leur engagement en faveur de la protection de l'environnement et de la biodiversité".
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