Energy consumption of wastewater treatment being the largest cost component, Stadtwerke Trier [SWT] took a major step forward in 2013 to improve the energy and resource efficiency of its WWTP not only to reduce the costs but also to improve the environmental compatibility of its operations. Key drivers for resource efficiency at SWT WWTP include process optimisation, energy­‐efficient technologies, onsite renewable energy generation, and integrated intelligent process management technology.

A key highlight of this plant is the production of renewable energy

a.) via  the utilization of organic matter of  sewage  sludge  in  an anaerobic digester (ca. 2.7 million kWh/a),
b.) through a roof-­mounted PV plant (ca. 70,000 kWh/a), and
c.) through flow­‐turbines and energy recovery etc. (ca. 0.51 million kWh/a) making the complete wastewater treatment process an energy autarky system.

As can be seen, the bulk of the energy is produced through biogas, which is used in an on-site CHP unit to produce heat and electricity.


  • SWT WWTP has saved ca. one million kWh per annum through energy efficiency implementation whereas it produces ca. 3.3 million kWh/a
  •  The GHG abatement of the plant amounts to 2kt CO2-­‐eq/a
  • Energy surplus of the plant as of 2016 amounts to 0.2 million kWh/a