ARNEX SUR ORBE Wastewater Treatment Plant, Arnex-sur-Orbe, Vaud, Switzerland

ARNEX SUR ORBE is an advanced wastewater treatment plant located in Arnex-sur-Orbe, a municipality in the canton of Vaud, Switzerland. The plant serves a small population of approximately 400 residents, reflecting the rural character of the Jura-Nord vaudois district. Its design capacity of 938 cubic meters per day indicates it is sized for local community needs. The plant employs advanced treatment processes, which go beyond secondary treatment to remove nutrients and micropollutants. Under Swiss water protection law (Gewässerschutzgesetz), advanced treatment is required for plants discharging into sensitive water bodies. The plant's current discharge volume of 182 m³/day suggests it operates well below capacity, with room for future growth. The treated effluent from ARNEX SUR ORBE flows into the Orbe River, a tributary of the Thièle, which eventually joins the Zihl Canal and drains into Lake Biel (Bielersee). This lake is part of the Aare-Rhine system, ultimately reaching the North Sea. The plant plays a key role in protecting the Orbe River and downstream aquatic habitats from nutrient pollution.

The plant discharges into the Orbe River, which flows through the Jura region into the Thièle River and then into Lake Biel (Bielersee). Lake Biel is an ecologically important water body that supports diverse fish populations and serves as a migratory corridor for birds. The advanced treatment at ARNEX SUR ORBE helps reduce nutrient loads, protecting the lake from eutrophication and maintaining water quality for downstream ecosystems.