OBERNZENN Wastewater Treatment Plant, Unternzenn, Bavaria

OBERNZENN is a former wastewater treatment plant located in Unternzenn, a district of Obernzenn in the Bavarian region of Germany. It served a small population of 1,194 people, typical of a rural agglomeration. The plant is now closed, and its operational history reflects the infrastructure needs of this community. The plant provided secondary treatment, which is the standard biological treatment required under the EU Urban Waste Water Treatment Directive (91/271/EEC) for agglomerations of this size. Although the designed capacity was 2,500 m³/day, the actual discharge volume was 302.17 m³/day, indicating the plant operated well below its capacity. Secondary treatment typically involves biological processes such as activated sludge or trickling filters. The treated effluent was discharged into local water bodies that ultimately drain into the Rhine River basin via the Regnitz and Main rivers. The plant's closure may be due to consolidation of wastewater services in the region. The surrounding area is characterized by agricultural land and small settlements, with the Zenn River flowing nearby.

The plant discharged into the Zenn River, a tributary of the Aisch, which flows into the Regnitz and then the Main River, part of the Rhine basin. The Rhine is a major European waterway supporting diverse aquatic life and providing drinking water for millions. The region's watershed is sensitive to nutrient pollution from agriculture, and the plant's secondary treatment helped reduce organic load before discharge.