Grunenbach Wastewater Treatment Plant, Schönau, Bayern

The Grunenbach wastewater treatment plant is located in Schönau, within the municipality of Grünenbach in the Landkreis Lindau district of Bayern, Germany. It serves a population of approximately 7,200, placing it in the small-to-medium agglomeration category under German and EU regulations. The plant employs advanced treatment processes, which go beyond the secondary treatment required by the EU Urban Waste Water Treatment Directive (91/271/EEC) for agglomerations of this size. With a designed capacity of 11,250 m³/day and an average discharge volume of 317.66 m³/day, the facility operates well below its capacity, indicating robust infrastructure for current loads. The treated effluent is discharged into local watercourses that eventually drain into the Rhine basin and ultimately the North Sea. The plant's advanced treatment helps protect downstream aquatic ecosystems, including sensitive areas in the Alpine foothills, by reducing nutrient loads and pollutants.

The plant discharges into small streams in the Argental region, which flow into the Weißach River, a tributary of the Bregenzer Ach. This river system drains into Lake Constance (Bodensee), a major drinking water reservoir and ecologically sensitive lake, before continuing via the Rhine to the North Sea. The advanced treatment helps safeguard water quality in this transboundary watershed, supporting diverse aquatic life and recreational uses.