UWWTP Vrhnika Tojnice - Primary Wastewater Treatment Plant in Vrhnika, Slovenia

UWWTP Vrhnika Tojnice is a municipal wastewater treatment plant located in the Tojnice industrial-commercial zone near Vrhnika, Slovenia. The plant serves a population of approximately 5,702 people and is part of the country's wastewater infrastructure managed under Slovenian environmental regulations. The plant provides primary treatment, which involves physical processes such as sedimentation to remove settleable solids. With a designed capacity of 15,500 m³/day and an average discharge volume of 890.62 m³/day, the facility operates well below its capacity. Under the EU Urban Waste Water Treatment Directive (91/271/EEC), agglomerations of this size (5,702 PE) are generally required to provide secondary treatment, though primary treatment may be acceptable if the receiving waters are not sensitive. The treated effluent is discharged into local watercourses that eventually drain into the Ljubljanica River basin, part of the Sava River catchment, which flows into the Danube River and ultimately the Black Sea. The plant plays a key role in protecting the local aquatic environment from untreated wastewater pollution.

The plant discharges into the Ljubljanica River basin, a karstic watershed in central Slovenia. The Ljubljanica flows into the Sava River, a major tributary of the Danube, which drains into the Black Sea. The region supports diverse aquatic life, including fish species such as the Danube salmon, and the karst geology makes groundwater particularly vulnerable to contamination. Effective treatment is essential to protect both surface and groundwater quality in this ecologically sensitive area.