Ketrzyn Wastewater Treatment Plant, Biedaszki Małe, Poland

The Ketrzyn wastewater treatment plant is located in Biedaszki Małe, within the warmińsko-mazurskie voivodeship of Poland. It serves a population equivalent of 46,902, classifying it as a medium-sized agglomeration under EU regulations. The plant is situated inland, approximately 50 km from the Baltic Sea coast. As a Polish facility, the plant operates under the EU Urban Waste Water Treatment Directive 91/271/EEC, which requires secondary treatment for agglomerations between 10,000 and 150,000 population equivalent. Poland's national regulations transpose this directive, and the plant is subject to permits issued by the Regional Water Management Board (RZGW). The regulatory framework ensures compliance with effluent standards. The plant discharges treated wastewater into local watercourses that eventually drain into the Baltic Sea via the Pregola River basin. The warmińsko-mazurskie region is known for its numerous lakes and wetlands, which support diverse aquatic life and migratory birds. Proper treatment is essential to protect these sensitive ecosystems from nutrient pollution and eutrophication.

The Ketrzyn plant discharges into the Pregola River basin, which flows through the Vistula Lagoon and ultimately into the Baltic Sea. The region features numerous lakes and wetlands that are ecologically sensitive, supporting diverse aquatic life and serving as important migratory corridors for birds. Nutrient removal is critical to prevent eutrophication in the Baltic Sea, a semi-enclosed sea already affected by excessive nitrogen and phosphorus loads.