Wisznice Wastewater Treatment Plant, Dubica Dolna, Poland

The Wisznice wastewater treatment plant is located in Dubica Dolna, within the gmina Wisznice in województwo lubelskie, Poland. It serves a population of approximately 1,334 people, classifying it as a small agglomeration under Polish and EU regulations. The plant operates under the framework of the EU Urban Waste Water Treatment Directive (91/271/EEC), which requires secondary treatment for settlements of this size discharging into freshwater. The plant provides secondary treatment, which typically involves biological processes to reduce organic matter and suspended solids. Its designed capacity is 3,480 cubic meters per day, with an actual discharge volume of 190.21 cubic meters per day, indicating significant spare capacity. The plant's operations are subject to Polish water law and EU directives, ensuring compliance with effluent standards for inland waters. The treated effluent is discharged into local watercourses that eventually drain into the Bug River, a major tributary of the Narew and Vistula rivers, which flow into the Baltic Sea. The plant plays a key role in protecting the local watershed from nutrient pollution, supporting aquatic life and downstream ecosystems in the Bug River basin.

The plant discharges into local streams that feed into the Bug River, which flows through eastern Poland and forms part of the border with Belarus and Ukraine. The Bug River is an ecologically significant waterway, supporting diverse fish populations and riparian habitats. Downstream, the river joins the Narew and eventually the Vistula, which empties into the Baltic Sea. The plant's secondary treatment helps reduce organic and nutrient loads, mitigating eutrophication risks in this sensitive river system.