STEP SEPE Wastewater Treatment Plant, Porrentruy, Jura, Switzerland

STEP SEPE is a municipal wastewater treatment plant located in Porrentruy, in the canton of Jura, Switzerland. The plant serves a population of approximately 16,117 people, making it a medium-sized facility within the Swiss wastewater infrastructure. As a Swiss plant, STEP SEPE operates under the Swiss Water Protection Act (Gewässerschutzgesetz), which mandates advanced treatment standards. For agglomerations of this scale, secondary treatment with nutrient removal is typically required to protect sensitive water bodies. The plant's treatment processes are designed to meet these stringent national regulations. The treated effluent from STEP SEPE is discharged into the local watershed, which ultimately drains into the Rhine River basin via the Allaine River. The Rhine is a major European waterway that flows into the North Sea, supporting diverse aquatic ecosystems and providing drinking water for millions. The plant plays a key role in maintaining water quality in this transboundary river system.

STEP SEPE discharges into the Allaine River, a tributary of the Doubs River, which flows into the Rhine River basin. The Rhine ultimately reaches the North Sea, supporting a rich ecosystem including migratory fish species such as salmon and eel. The plant's location in the Jura region, with its karst geology, requires careful management to prevent groundwater contamination. The Swiss regulatory framework ensures high treatment standards to protect these downstream waters.