SULLENS Wastewater Treatment Plant, Penthaz, Vaud, Switzerland

SULLENS is a wastewater treatment plant located in Penthaz, within the District du Gros-de-Vaud in the canton of Vaud, Switzerland. It serves a population of 1,122 and operates with advanced treatment processes, ensuring high-quality effluent. The plant has a designed capacity of 1,875 m³/day and currently discharges 509.30 m³/day of treated wastewater. As an advanced treatment facility, SULLENS meets the stringent requirements of Swiss water protection legislation, which aligns with the EU Urban Waste Water Treatment Directive. For a small agglomeration of this size, advanced treatment is typically required in sensitive areas to protect receiving waters from nutrient pollution. The plant's treated effluent is discharged into local watercourses that eventually drain into the Rhône River basin, which flows into Lake Geneva (Lac Léman) and then the Mediterranean Sea. The proximity to Lake Geneva, a large and ecologically important lake, underscores the need for high treatment standards to protect water quality and aquatic life.

The SULLENS plant discharges into local streams that are part of the Rhône River basin, ultimately reaching Lake Geneva and the Mediterranean Sea. Lake Geneva is a large, deep lake that supports diverse aquatic ecosystems, including fish species such as Arctic char and whitefish. The advanced treatment helps minimize nutrient loading, which is critical to prevent eutrophication and maintain the lake's ecological balance.