Despite very limited space, the Birsig wastewater treatment plant in Therwil had to increase its capacity and install a new process stage for the elimination of micropollutants. Thanks to a new primary clarification stage, the biological stage can be maintained at its current size. Biogas is produced from the sludge in the primary treatment stage in a digester and converted into electricity in a combined heat and power plant (CHP). This enables the treatment plant to meet part of its own electricity needs. Excess heat is fed into a district heating network.

Our tasks

  • Development of a resource-saving solution
  • Planning and support


Dr. Michael Mattle

Head of Wastewater Technology