Lindholmen Avloppsanlaggning - Norrtälje Wastewater Treatment Plant, Sweden

Lindholmen Avloppsanlaggning is a wastewater treatment plant located in Norrtälje, a coastal town in Stockholm County, Sweden. The facility serves a population of approximately 29,801, placing it in the medium-agglomeration category under EU regulations. As part of Sweden's municipal wastewater infrastructure, the plant plays a key role in protecting local water quality. Under the EU Urban Waste Water Treatment Directive (91/271/EEC), agglomerations of this size (between 10,000 and 100,000 population equivalent) are required to provide secondary treatment as a minimum. In sensitive areas, such as those draining into the Baltic Sea, more stringent tertiary treatment may be mandated to reduce nutrient loads. The plant's designed capacity is 1.00 (likely in thousands of cubic meters per day or similar unit), indicating a facility scaled to its service population. The treated effluent from Lindholmen is discharged into the local watershed, which ultimately drains into the Baltic Sea. The Baltic Sea is a semi-enclosed brackish sea with limited water exchange, making it highly sensitive to nutrient pollution. Effective treatment at plants like Lindholmen is critical to reducing eutrophication and maintaining the ecological health of coastal and marine environments in the region.

The plant's receiving waters flow into the Baltic Sea, a brackish inland sea with limited circulation and high sensitivity to nutrient inputs. Eutrophication from nitrogen and phosphorus is a major ecological concern, leading to algal blooms and oxygen depletion. The plant's location in Stockholm County places it within a region where stringent nutrient removal is often required to protect coastal ecosystems and support biodiversity, including fish spawning grounds and migratory bird habitats.