Osiek Wastewater Treatment Plant, Karszanek | Poland

Osiek wastewater treatment plant is located in the village of Karszanek, within the gmina of Osiek in the powiat starogardzki of Poland's Pomeranian Voivodeship. The plant serves a population of 706 residents, making it a small-scale municipal facility. It operates under Poland's implementation of the EU Urban Waste Water Treatment Directive (91/271/EEC), which requires secondary treatment for agglomerations of this size. The plant provides secondary treatment, a standard biological process that removes organic matter and suspended solids. Its designed capacity is 2,167 m³ per day, with an actual discharge volume of about 101 m³ per day, indicating significant spare capacity. As a small inland facility, it does not face the stringent nutrient removal requirements applied to larger plants discharging into sensitive areas. The treated effluent is discharged into local surface waters, likely a small stream or river within the Vistula River basin. The Vistula flows northward into the Baltic Sea, making the plant part of a larger watershed that supports diverse aquatic life and contributes to the ecological health of the Baltic coastal zone.

The plant discharges into a local watercourse within the Vistula River basin, which drains into the Baltic Sea. The Baltic Sea is a semi-enclosed, brackish sea with limited water exchange, making it sensitive to nutrient pollution. The plant's secondary treatment helps reduce organic load, but without tertiary nutrient removal, it may contribute to eutrophication in downstream waters. The surrounding area is rural and agricultural, with potential diffuse pollution sources.