New technology for the environmentally friendly wastewater treatment is now to be installed: By the end of 2022, the Eifel-Rur Water Association is investing around 4,00 million Euros in the conversion of four secondary settling tanks at Wastewater Treatment Plant Aachen-Soers in order to effectively relieve the polluted water load. The ozonation plant has already been built and, as the largest in Europe, integrated into the existing wastewater treatment system. The wastewater treatment plant has been treating the wastewater of the city of Aachen since 1913 and is dimensioned for 458,300 population equivalents. By 2022, four secondary settling tanks will be upgraded step by step with new stainless steel central structures and height-adjustable inlet structures. The DN 700 return sludge pipes will be replaced by new stainless steel pipes. The optimization of the secondary clarification system is expected to increase the capacity by approx. 20%. A joint venture with DAHLEM as lead company has been commissioned with the project and specialist planning. The state of NRW is funding both the large-scale technical implementation and the accompanying research on the entire project of the wastewater treatment plant.