Trosa Avloppsreningsverk - Advanced Wastewater Treatment Plant in Trosa, Sweden

Trosa Avloppsreningsverk is a municipal wastewater treatment plant located in Trosa, Södermanlands län, Sweden. The facility serves a population of approximately 4,134 residents, making it a small-scale plant within the Swedish wastewater infrastructure. The plant employs advanced treatment processes, which go beyond secondary treatment to remove nutrients and other pollutants. With a designed capacity of 6,000 m³/day and a current discharge volume of about 649 m³/day, the plant operates well within its capacity. As a Swedish facility, it complies with national regulations that implement the EU Urban Waste Water Treatment Directive (91/271/EEC), which requires advanced treatment for sensitive areas. The treated effluent is discharged into the local watershed, which ultimately drains into the Baltic Sea. The plant plays a key role in protecting the coastal and marine environment of the Baltic Sea, a sensitive water body prone to eutrophication. By providing advanced treatment, Trosa Avloppsreningsverk helps reduce nutrient loads and supports the ecological health of the region.

The plant discharges treated wastewater into the local water system, which flows into the Baltic Sea via the Trosaån river or nearby coastal waters. The Baltic Sea is a brackish, semi-enclosed sea with limited water exchange, making it highly sensitive to nutrient pollution. Advanced treatment at this plant helps mitigate eutrophication, supporting diverse aquatic life and maintaining water quality in the coastal zone.