OBFELDEN Wastewater Treatment Plant, Obfelden, Zurich, Switzerland

OBFELDEN is a wastewater treatment plant located in Obfelden, a municipality in the Bezirk Affoltern district of the canton of Zürich, Switzerland. The plant serves a population of about 5,208 people, reflecting its role in managing domestic wastewater for this small agglomeration within the Zurich metropolitan area. As a Swiss treatment facility, OBFELDEN operates under the Swiss Water Protection Act (Gewässerschutzgesetz), which mandates appropriate treatment levels based on receiving water sensitivity. For plants of this scale, secondary treatment with nutrient removal is typically required to protect local water bodies. Swiss regulations ensure compliance with stringent effluent standards. The treated effluent from OBFELDEN is discharged into the local hydrological network, which ultimately drains into the Reuss River via the Lorze and then into the Rhine River. The Rhine basin is a major European waterway supporting diverse aquatic ecosystems and providing drinking water for millions. The plant's operations contribute to maintaining water quality in this ecologically significant catchment.

OBFELDEN discharges into the local stream system that feeds the Lorze River, a tributary of the Reuss, which flows into the Rhine River. The Rhine basin is a critical freshwater resource supporting diverse fish species, including salmon and eel, and provides habitat for numerous aquatic organisms. The plant's location in the Zurich uplands means its effluent influences downstream water quality in this sensitive alpine-to-lowland transition zone.