Norsa Avloppsreningsverk - Köping Wastewater Treatment Plant, Sweden

Norsa Avloppsreningsverk is a municipal wastewater treatment plant located in Köping, Västmanland County, Sweden. It serves a population of around 18,500, classifying it as a medium-sized agglomeration under EU standards. The plant is situated near the coast of Lake Mälaren, a major freshwater lake that drains into the Baltic Sea. As a Swedish facility, the plant operates under the EU Urban Waste Water Treatment Directive (91/271/EEC), which requires secondary treatment for agglomerations of this size. Sweden's national regulations enforce strict nutrient removal standards, particularly for phosphorus and nitrogen, to protect sensitive water bodies like the Baltic Sea. The plant's designed capacity is 1.00 (likely in thousands of cubic meters per day), indicating a moderate scale. The treated effluent is discharged into the local watershed, which ultimately flows into Lake Mälaren and then through the Stockholm archipelago to the Baltic Sea. This region is ecologically sensitive due to eutrophication risks, and the plant's treatment processes are critical for maintaining water quality in the lake and downstream marine environment.

The plant discharges into the Köping River system, which flows into Lake Mälaren, Sweden's third-largest lake. Lake Mälaren drains via the Stockholm archipelago into the Baltic Sea, a brackish sea vulnerable to nutrient pollution. The watershed supports diverse aquatic life and provides drinking water for millions. Nutrient removal at the plant helps mitigate algal blooms and oxygen depletion in the Baltic Sea.