Mikosze II Wastewater Treatment Plant, Mikosze-Osada, Poland

Mikosze II is a municipal wastewater treatment plant located in Mikosze-Osada, within the gmina of Orzysz in the Warmian-Masurian Voivodeship of Poland. The plant serves a population of approximately 6,600 residents, classifying it as a small to medium agglomeration under Polish and EU regulations. The plant provides secondary treatment, which is the minimum standard required by the EU Urban Waste Water Treatment Directive (91/271/EEC) for agglomerations of this size. With a designed capacity of 18,000 m³/day and an actual discharge volume of about 943 m³/day, the plant operates well below its capacity, indicating room for future growth or seasonal variations. The treated effluent is discharged into local watercourses that drain into the Pisa River, a tributary of the Narew River, which ultimately flows into the Vistula River and then the Baltic Sea. The plant plays a key role in protecting the region's lakes and rivers from nutrient pollution, supporting aquatic biodiversity and recreational water quality.

The plant discharges into the local watershed, which feeds into the Pisa River and then the Narew River, part of the Vistula basin that drains into the Baltic Sea. The Warmian-Masurian region is known for its numerous lakes and ecologically sensitive areas, making effective nutrient removal critical to prevent eutrophication. The secondary treatment helps reduce organic load and suspended solids, supporting the health of downstream aquatic ecosystems.