Sampling campaign in Croatia

The Croatian sampling sites

First sampling campaign November 2024

Sampling sites for wastewater in Croatia were selected both in the sub-basin of Sava river and sub-basin of Drava and Danube river. An emphasis was on treated urban wastewaters at the outlet of wastewater treatment plants in four agglomerations with different total generated load – agglomeration Zagreb with 850.000 PE, Osijek 141.500 PE, Slavonski Brod 76.000 PE and Sisak 39.700 PE. Although total load is mostly generated by resident population, in large cities the discharges of industrial sites are also connected to the public collecting system, significantly contributing to possible pollution with dangerous substances such as metals or different organic compounds. Main sources of industrial wastewaters are from food industry (milk and dairy, brewery, confectionary, oil, bakery), from chemical industry (detergents and cleaning products, cosmetics, pharmaceutical industry), metal industry waste disposal sites but also from clinical hospitals.

Sampling points were also determined on the rivers in order to examine the possible presence of contamination by selected dangerous substances in the surface waters. In Croatia, four sampling locations were selected - two on the Drava river (near Botovo and downstream from Osijek, 4 km before confluence with Danube), one on the Kupa river (near Donje Mekušje) and one on the Sava river (near Oborovo).

The first sampling campaign was successfully carried out during the first week of the November at all four selected wastewater treatment plants. During November, sampling at monitoring points on the rivers was also carried out as planned.

The weather conditions were stable during the entire sampling period, completely without precipitation or bad weather, which ensured a significant prerequisite for uniform sample quality, especially for wastewaters which were sampled as 7-days composite.

Wastewater treatment plants