ROWP Calinesti Oas Wastewater Treatment Plant, Călinești-Oaș, Romania

ROWP Calinesti Oas is a municipal wastewater treatment plant located in Călinești-Oaș, Satu Mare County, Romania. The facility serves a small population of 450 residents, reflecting the rural character of the area. As a secondary treatment plant, it provides biological treatment to reduce organic matter and suspended solids before discharge. The plant operates under Romania's implementation of the EU Urban Waste Water Treatment Directive (91/271/EEC), which requires secondary treatment for agglomerations with a population equivalent (PE) between 2,000 and 10,000. Although the population served here is below that threshold, the plant still meets secondary treatment standards, indicating a commitment to environmental protection. The designed capacity is 1,562 m³/day, with an actual discharge volume of 44.06 m³/day, suggesting ample capacity for current loads. The treated effluent is discharged into a local watercourse that eventually drains into the Tisza River basin, part of the larger Danube River system. This water body supports diverse aquatic life and is important for regional biodiversity. The plant's operation helps protect downstream water quality in the Tisza and Danube catchments.

The plant discharges into a small tributary of the Tisza River, which flows through the Carpathian Basin before joining the Danube River and ultimately the Black Sea. The local watershed supports mixed forest and agricultural land uses, and the water body provides habitat for fish and macroinvertebrates. Protecting water quality here is important for maintaining the ecological health of the Tisza-Danube system, which is a major European river corridor.