What happens to our wastewater? Entsorgung + Recycling Zürich (ERZ) invites you to visit the Werdhölzli wastewater treatment plant in Zurich—a state-of-the-art facility with five treatment stages. On a guided tour featuring various stops, you’ll discover how the Werdhölzli plant is preparing for the future.

It all began in 1926 with a simple settling tank. The current Werdhölzli plant was built in the 1980s. Today, it is the largest wastewater treatment plant in Switzerland: About 2,200 liters of wastewater flow through it every second, and during heavy rain, that figure can rise to as much as 6,000 liters.

To keep pace with population growth and meet legal requirements, the facility will need to be expanded in the coming years. The pilot phase is currently underway. Using the biological treatment stage as an example, ERZ demonstrates how technological innovations and capacity expansions are implemented during ongoing operations: from preliminary studies through a pilot plant to implementation.