Ciechanow Wastewater Treatment Plant: Serving Ciechanów, Poland under EU UWWTD

The Ciechanow wastewater treatment plant is a municipal facility located in Szczurzynek, Ciechanów, in the Mazowieckie region of Poland. It serves a population of approximately 165,726 people, classifying it as a large agglomeration under EU regulations. The plant is situated inland, more than 50 km from the Baltic Sea coast. As a Polish facility serving over 150,000 population equivalent, the plant is subject to the EU Urban Waste Water Treatment Directive (91/271/EEC). This directive requires secondary biological treatment for all agglomerations above 2,000 PE, and more stringent tertiary treatment for discharges into sensitive areas. The plant's treatment processes are designed to meet these standards, ensuring compliance with Polish and EU water quality regulations. The treated effluent is discharged into local watercourses that ultimately drain into the Vistula River basin, which flows northward into the Baltic Sea. The plant plays a critical role in protecting the region's surface waters from nutrient pollution and organic load, supporting aquatic life and downstream ecosystems in the Vistula catchment.

The Ciechanow plant discharges into the Łydynia River, a tributary of the Wkra River, which flows into the Narew River and eventually the Vistula River. The Vistula drains into the Baltic Sea, a semi-enclosed sea sensitive to eutrophication from nutrient inputs. The plant's treatment helps reduce nitrogen and phosphorus loads, mitigating algal blooms and supporting biodiversity in the Vistula delta and Baltic coastal waters.