Olesnica Wastewater Treatment Plant, Wojnów, Poland

The Olesnica wastewater treatment plant is located in Wojnów, a village in the gmina of Oleśnica, świętokrzyskie voivodeship, Poland. It serves a small population of 168 residents, reflecting its role in a rural community. The plant is situated in a region characterized by agricultural landscapes and scattered settlements. The plant provides secondary treatment, which is the standard biological treatment required under the EU Urban Waste Water Treatment Directive (91/271/EEC) for agglomerations with a population equivalent (PE) between 2,000 and 10,000. Although the population served is below this threshold, the plant's designed capacity of 3,500 m³/day suggests it may also handle industrial or seasonal loads. The actual discharge volume is 23.95 m³/day, indicating low utilization relative to capacity. The treated effluent is discharged into local watercourses that eventually drain into the Vistula River basin, which flows northward to the Baltic Sea. The plant's operation helps protect the region's surface waters from nutrient pollution, supporting aquatic life and downstream ecosystems in the Vistula delta and the Baltic Sea.

The plant discharges into small streams that are part of the Vistula River basin, Poland's largest river system. The Vistula flows into the Baltic Sea via the Gdańsk Bay. The region's watershed supports diverse aquatic habitats and is important for migratory fish species. The plant's secondary treatment reduces organic load and nutrients, helping to mitigate eutrophication risks in the Baltic Sea, a semi-enclosed sea sensitive to nutrient inputs.