Undløse Wastewater Treatment Plant, Undløse, Denmark - Closed Facility

Undløse wastewater treatment plant is located in the small town of Undløse, Holbæk Kommune, in Denmark's Region Sjælland. It served a population of approximately 809 people, classifying it as a small agglomeration under Danish and EU regulations. The plant is currently closed. The plant provided secondary treatment, which is the standard required by the EU Urban Waste Water Treatment Directive for discharges into freshwater and estuaries from agglomerations of this size. Its designed capacity was 2,600 m³/day, with an average discharge volume of 160.29 m³/day, indicating low utilization before closure. The plant operated under Denmark's implementation of the EU directive, which mandates treatment levels based on receiving water sensitivity. The treated effluent was discharged into local watercourses that eventually drain into the Isefjord or the Great Belt, part of the Baltic Sea. The region's watershed supports diverse aquatic life and is important for migratory birds. The closure likely means wastewater is now diverted to a larger regional plant, improving treatment efficiency and environmental protection.

The plant's discharge entered local streams that flow into the Isefjord, a shallow fjord connected to the Kattegat and the Baltic Sea. This coastal ecosystem supports diverse marine life, including fish spawning grounds and bird habitats. The region's watershed is sensitive to nutrient loading, making secondary treatment important for protecting water quality in downstream coastal areas.