Vienna’s wastewater management and water protection plan

Vienna Main Wastewater Treatment Plant Simmering

In 1998, Wien Kanal developed a plan for "Ecological and economical optimisation of wastewater disposal and water protection in Vienna" together with wastewater treatment plan operator Entsorgungsbetriebe Simmering and Municipal Department 45 - Water Management (MA 45).

The principle of this approach was to consider all elements of Vienna’s wastewater treatment and water protection as a holistic project that can be optimised ecologically and economically, starting not at the drain but the source. It seeks to address the global problem of constantly increasing wastewater and its disposal with new, economically efficient approaches. The principle "avoidance before disposal" means no longer relying primarily on end-of-pipe solutions. Instead, the city promotes quantitative and qualitative measures directly at the source:

• Uncontaminated rainwater runoff is allowed to soak into the ground
• Reduction of paved and sealed surfaces
• Awareness-raising campaigns à la "the sewer is not a waste bin"

Numerous simulations during the programme development showed that this has considerable economic benefits as less storage reservoirs are needed and the required mixed water throughput of the wastewater treatment plants is reduced. The innovative approach made it possible to reduce the maximum inflow to the treatment plant from 24 to 18 cubic metres per second. This made the expansion of the wastewater treatment plant considerably more economical due to a smaller required size and created more stable conditions for its operation.

Steering the wastewater flows

New measures were also implemented in the sewer network management. Enormous storage sewers underneath the Liesingbach brook and the River Wien as well as a city-wide network of regulating valves ensure a steadier flow of sewage to the wastewater treatment plant. 20 precipitation monitoring stations and 40 flow rate measuring stations provide real-time wastewater data for the whole city, making it possible to control wastewater flows via regulating valves and distribute them in the sewer system so as to mitigate peak loads in the wastewater treatment plant.