Today's sewage treatment plants use an "activated sludge process" where wastewater pollutants are oxidized to carbon dioxide by microorganisms with the addition of oxygen and rendered harmless. However, the energy potential of the wastewater is also almost completely lost. In Europe, around 1600 gigawatt hours of electricity are used annually for this cleaning process. After all, this is the annual energy production of two large power plants with an output of 1000 MW.
In order to prove that sewage treatment plants can be not only energy destroyers but also energy producers, the Kompetenzzentrum Wasser Berlin (KWB) together with 15 European partners from industry and research carried out the 3-year research project POWERSTEP.
The scientists tested various technical approaches to generating more electrical energy from the wastewater treatment plants than they consume. The organic substances contained in the wastewater contain so much chemical energy that, using innovative technologies, the energy previously required for the purification process could be completely compensated and even an excess could be achieved.