GROLLEY Wastewater Treatment Plant, Grolley-Ponthaux, Fribourg/Freiburg, Switzerland

GROLLEY wastewater treatment plant is located in Grolley-Ponthaux, in the canton of Fribourg/Freiburg, Switzerland. The plant serves a population equivalent of 1,746 and treats wastewater to secondary level before discharge. Its designed capacity is 2,917.00 m³/day, with an average daily flow of 792.55 m³/day. As a Swiss facility, GROLLEY operates under the Swiss Water Protection Act (Gewässerschutzgesetz), which mandates secondary treatment for agglomerations of this size. The plant's secondary treatment process ensures compliance with national standards for organic matter and suspended solids removal, protecting receiving waters from pollution. The treated effluent is discharged into local watercourses that drain into the Sarine River, a tributary of the Aare River, which ultimately flows into the Rhine River and the North Sea. The plant plays a key role in safeguarding the ecological health of the Sarine basin, supporting aquatic life and downstream water quality.

The plant discharges into the Sarine River basin, part of the Rhine watershed that drains to the North Sea. The receiving waters support diverse aquatic ecosystems, including fish species such as brown trout and grayling. The plant's secondary treatment helps maintain water quality in this ecologically sensitive region, where agricultural and urban pressures require careful nutrient management.