Stawiski Wastewater Treatment Plant - Secondary Treatment in Podlaskie, Poland

The Stawiski wastewater treatment plant is located in the town of Stawiski, within the gmina of Stawiski, powiat kolneński, in województwo podlaskie, Poland. This facility serves a small population of 251 residents, reflecting its role in a rural community. The plant is part of Poland's municipal wastewater infrastructure, which operates under the EU Urban Waste Water Treatment Directive (91/271/EEC). The plant provides secondary treatment, which is the minimum standard required by the EU directive for agglomerations of this size. The designed capacity is 2,451 m³/day, and the current discharge volume is 35.79 m³/day, indicating that the plant operates well below its capacity. As a secondary treatment facility, it removes organic matter and suspended solids, but does not include advanced nutrient removal. The treated effluent is discharged into local watercourses that eventually drain into the Narew River basin, a major tributary of the Vistula River. The region is characterized by agricultural landscapes and small water bodies. The plant's operation helps protect the local watershed from untreated sewage, supporting water quality in downstream ecosystems.

The Stawiski plant discharges into the local drainage network that feeds into the Narew River, which flows into the Vistula River and ultimately the Baltic Sea. The area is part of a sensitive watershed where nutrient pollution from agriculture and wastewater can impact downstream aquatic habitats. The plant's secondary treatment reduces organic load, but without tertiary treatment, nutrient removal is limited, which is a consideration for the Baltic Sea eutrophication concerns.