SBR Radocza Wastewater Treatment Plant, Sopotnia Wielka, Poland

SBR Radocza is a municipal wastewater treatment plant located in Sopotnia Wielka, a village in the Żywiec County of southern Poland's Silesian Voivodeship. The plant serves a small population of 661 residents and operates with a designed capacity of 1,401 m³/day, currently discharging 94.25 m³/day of treated effluent. The plant provides secondary treatment, which is the standard biological treatment required under the EU Urban Waste Water Treatment Directive (91/271/EEC). For small agglomerations under 2,000 population equivalent, the directive mandates appropriate treatment to meet receiving water quality objectives. The plant's treatment process is based on sequencing batch reactor (SBR) technology, a variant of the activated sludge process that combines biological treatment and sedimentation in a single reactor. The treated effluent is discharged into a local watercourse that eventually drains into the Soła River, a tributary of the Vistula River. The Vistula flows northward through Poland to the Baltic Sea. The plant plays a key role in protecting the Soła River basin from nutrient pollution, supporting aquatic life and downstream water quality in the Vistula catchment.

The plant discharges into a small stream in the Carpathian foothills, which flows into the Soła River, a major tributary of the Vistula. The Soła River supports diverse aquatic ecosystems and is used for hydropower and recreation. Downstream, the Vistula River empties into the Baltic Sea via the Gdańsk Bay. The region is ecologically sensitive due to its mountainous terrain and proximity to the Żywiec Landscape Park, which hosts protected habitats. Proper treatment helps prevent eutrophication in the Baltic Sea, a concern under the Helsinki Convention.