Velika Gorica Wastewater Treatment Plant, Općina Rugvica, Croatia

The Velika Gorica wastewater treatment plant is located in Općina Rugvica, Zagrebačka županija, Croatia. It serves the local population as part of the region's municipal wastewater infrastructure. The plant has a designed capacity of 35,000 cubic meters per day, indicating it handles a significant volume of wastewater from the surrounding communities. As a secondary treatment facility, the plant employs biological processes to reduce organic matter and suspended solids. Under the EU Urban Waste Water Treatment Directive (91/271/EEC), secondary treatment is the standard requirement for inland discharges, ensuring compliance with European environmental standards. The plant's capacity suggests it serves a medium to large agglomeration, which would typically require advanced treatment if discharging into sensitive areas. The treated effluent is discharged into local watercourses that eventually drain into the Sava River basin, a major tributary of the Danube. The Sava River supports diverse aquatic life and is an important ecological corridor in the region. Proper treatment at Velika Gorica helps protect downstream water quality and the broader Danube ecosystem.

The plant's discharge enters local streams that flow into the Sava River, which ultimately joins the Danube River before reaching the Black Sea. The Sava River basin is ecologically significant, supporting diverse fish populations and serving as a migratory route for birds. The region's continental climate and agricultural land use mean that nutrient loading from wastewater could impact downstream water quality, making secondary treatment essential for maintaining ecological balance.