Xylem’s ozone technology helps Zurich wastewater plant to meet new Swiss regulations


Werdholzi wastewater treatment plant in Zurich, Switzerland has awarded a contract to Xylem to provide ozone water treatment technology.

The wastewater treatment plant in Zurich is considered to be one of the largest facilities in Switzerland that serves more than 434,000 people. The water treatment technology from Xylem will help Zurich in meeting new Swiss regulations in protecting water bodies and particularly in eliminating micropollutants.

For upgrading the Werdholzi wastewater treatment plant, Xylem will supply eight of Wedeco SMOevo ozone systems at a cost of CHF50m ($51.17m).

With the installation of these machines, the plant in Zurich will be able to produce 153 kilograms of ozone per hour (kgO3/h) which will be used in treating at least 6,500 litres per second (l/s). Xylem claims that this will be the largest ozone utilizing plant for removing micropollutants in the world.

According to Xylem, many countries in the world today are facing the issue of treating wastewater containing micropollutants released from everyday products such as industrial chemicals, pharmaceuticals, personal care products, pesticides and hormones and these pollutants cannot be removed from conventional treatment technologies.

Xylem key account manager Florian Milz said: “The elimination of micropollutants from wastewater is a challenge which more and more facilities must address. While conventional treatment processes do not remove them completely, oxidation with ozone is proving to be one of the most efficient methods for reducing these contaminants.

“Pollutants, colored substances, odors and microorganisms are directly destroyed by oxidation, without creating harmful chlorinated by-products or significant residues.

“We are pleased to support this ambitious project in partnership with Carl Heusser AG, Xylem’s official distributor in Switzerland, by providing our Wedeco SMOevo ozone systems which combine maximum flexibility and reliable operating characteristics for operations of varying capacities.”

The European Union has put up a list of prioritised substances that have become a threat to both ground and surface water resources. Switzerland has taken up a process to upgrade major wastewater treatment plant after about 20 years. Under a new rule in the country, wastewater treatment plants had to remove additional micropollutants.

Entsorgung + Recycling Zürich chief operating officer Peter Wiederkehr said: “Wastewater treatment plants serving a population of 5,000 or more must be equipped now with a new treatment stage which ensures that up to 80% of pre-selected micropollutants are removed.

“Extensive research has confirmed ozone as a preferred technology for this stage. Xylem’s Wedeco SMOevo ozone systems will enable us to meet the new treatment regulations with a reliable, environmentally-friendly and cost-effective solution.”