Mettmann Obschwarzbach Wastewater Treatment Plant, Mettmann, Germany

Mettmann Obschwarzbach is a former wastewater treatment plant located in the Obschwarzbach district of Mettmann, in the state of Nordrhein-Westfalen, Germany. The plant was designed to serve a small population of 1,495 people, with a designed capacity of 2,500 cubic meters per day and a recorded discharge volume of 378.35 cubic meters per day. It is now closed and no longer operational. As an advanced treatment facility, Mettmann Obschwarzbach would have met the stringent requirements of the EU Urban Waste Water Treatment Directive (91/271/EEC), which mandates advanced (tertiary) treatment for sensitive areas. The plant's small scale aligns with Germany's decentralized wastewater management approach, where smaller communities often operate local treatment systems. The plant's discharge likely flowed into the Obschwarzbach stream, a tributary of the Rhine River basin. The Rhine is a major European waterway that drains into the North Sea, supporting diverse aquatic ecosystems and serving as a critical water resource for millions.

The plant's receiving water body was likely the Obschwarzbach, a small stream in the Rhine River basin. The Rhine flows through Germany and the Netherlands before discharging into the North Sea. This watershed supports important fish populations, including salmon and eel, and is a vital migratory corridor for aquatic species. The advanced treatment level would have helped protect local water quality and downstream ecosystems.