Renewal of biological stage and filtration (Capacity: 500'000 m3/d)

The Werdhölzli WWTP is the largest wastewater treatment plant in Switzerland and cleans the wastewater of the city of Zurich (approx. 600,000 inhabitants).
The project comprised the structural and mechanical renewal of the biological treatment stage and the filtration.

Special features:

• Conversion during on-going operations
• Conversion of aeration tanks from activated sludge to an alternating intermittent A/I process
• Convert the filtration cells with the bottom nozzle system to a spatial filter with pipeline drainage system

All the buildings were comprehensively renovated while certain objects were rebuilt. The mechanical equipment and almost all the electrical equipment was replaced with state-of-the-art technology.

The following structures and installations were renewed within the scope of the project:

• Construction of 2 new pumping stations
•  Biological stage
• Refurbishment of aeration tanks and replacement of aeration equipment including turbo compressors
• Replacement of precipitant treatment and dosing
• Revision of the final clarifiers
• Renewal of filtration
• Replacement of building technical systems
• Replacement of the EI&C installations

Services provided by SWISSWATER:

SWISSWATER received the entire engineering contract and implemented the project from concept, planning, cost and deadline monitoring to site management and acceptance.