Pieniezno Wastewater Treatment Plant, Pieniężno | Poland

The Pieniezno wastewater treatment plant is located in the town of Pieniężno, within the warmińsko-mazurskie province of northern Poland. It serves a population of approximately 3,287 residents, classifying it as a small agglomeration under Polish and EU regulations. The plant provides secondary treatment, which is the minimum standard required by the EU Urban Waste Water Treatment Directive (91/271/EEC) for inland freshwater discharges from agglomerations of this size. Its designed capacity is 6,000 m³/day, with an average daily discharge volume of about 469 m³, indicating ample reserve capacity for future growth. The treated effluent is discharged into local watercourses that ultimately drain into the Baltic Sea via the Pasłęka River basin. This region is part of the Vistula Lagoon catchment, an ecologically sensitive area that supports diverse aquatic life and migratory bird populations. Proper wastewater treatment is essential to protect the lagoon's water quality and the broader Baltic Sea ecosystem.

The plant's discharge flows into the Pasłęka River basin, which drains into the Vistula Lagoon and then the Baltic Sea. The lagoon is a shallow coastal water body that supports diverse aquatic life, including fish spawning grounds and migratory bird habitats. Nutrient loading from wastewater can contribute to eutrophication, making secondary treatment crucial for maintaining ecological balance in this sensitive coastal environment.