ARA Frenke 2 Wastewater Treatment Plant, Niederdorf, Basel-Landschaft

ARA Frenke 2 is a municipal wastewater treatment plant located in Niederdorf, within the canton of Basel-Landschaft, Switzerland. It serves a population of around 7,092 residents, placing it in the small-to-medium agglomeration category for Swiss wastewater infrastructure. Switzerland's Water Protection Act (Gewässerschutzgesetz) requires treatment plants of this scale to meet stringent effluent standards, typically through mechanical-biological treatment with nutrient removal. Swiss plants generally achieve high removal rates for organic matter and phosphorus to protect sensitive receiving waters. The plant discharges into local watercourses that drain into the Rhine River basin, ultimately reaching the North Sea. Its operation helps maintain water quality in the region's streams and supports the ecological health of downstream aquatic habitats.

The treated effluent from ARA Frenke 2 flows into small streams in the Waldenburg valley, which are part of the Rhine River basin. These waters eventually reach the North Sea. The region's aquatic ecosystems support diverse macroinvertebrate and fish communities, and the plant's treatment helps prevent nutrient enrichment and maintain oxygen levels in these sensitive water bodies.