The municipality of Rüti operates a wastewater treatment plant (WWTP) in Gruebensteg for about 14,500 inhabitants (approx. 16,750 population equivalents, including industry and commerce). The municipalities involved are Dürnten, with the village part Tann (2,650 PE) and Bubikon, area Kämmoos-Egelsee (350 PE).
In rainy weather, up to 250 l/sec of wastewater can be fed to the WWTP. Larger quantities are retained in stormwater tanks and later fed to the WWTP. After the 3-stage, i.e. mechanical-biological-chemical treatment, the wastewater is discharged into the Jona. Every year, about 11,500 m3 of digested sludge is dewatered and sent for incineration. The digester gas produced is processed in a combined heat and power plant and the electrical energy generated, approx. 250,000 kWh per year, is fed into the Rüti public utility grid. The waste heat is used to heat the digester rooms and the plant operation.
The WWTP was expanded between 1989 and 1994 and has been adapted to the new regulations to date. In the future, too, adjustments and renovations will be necessary on an ongoing basis due to new findings. Current planning goes up to 2020 and expects a load of up to 20,000 PE.
https://www.rueti.ch/topics/politik-verwaltung/verwaltung/abteilungen/klaranlage