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The aim of this study, conducted in accordance with both European Union and national legislation, was to evaluate the physicochemical conditions of the Rega River in northern Poland, where efforts are underway to restore its watershed for migratory fish. From 2018 to 2022, water temperature, dissolved oxygen (DO), pH, total suspended solids (TSS), conductivity, alkalinity, total hardness (TH), biochemical oxygen demand (BOD5), chemical oxygen demand (CODCr), nitrite nitrogen (NO2-N), ammonium nitrogen (NH4-N), and total phosphorus (TP) were measured at nine monitoring sites. The results showed that TSS and nitrite nitrogen (NO2-N) were the main factors threatening the suitability of the Rega River as a habitat for salmonid fishes. Additionally, maximum water temperatures occasionally exceeded the tolerance limits for these fishes. Seasonal variations in nitrogen and phosphorus forms, and the dependency of nitrogen forms on DO, indicated disruptions in natural biochemical processes due to surface runoff pollutants from the watershed. This includes fertilizer runoff from agricultural fields and municipal pollution from the towns through which the river flows. The findings underscore the need for continuous monitoring of Rega River waters to safeguard the habitat conditions required by environmentally sensitive fish species.

The health benefits and detrimental effects of coffee consumption may be linked to chemical compounds contained in coffee beans. The aim of our study was to evaluate the concentration of sodium (Na), potassium (K), calcium (Ca), magnesium (Mg), iron (Fe), copper (Cu), zinc (Zn), aluminum (Al), nickel (Ni), lead (Pb) and cadmium (Cd) in green and roasted samples of coffee beans purchased in Bosnia and Herzegovina, and to determine the potential health implications at current consumption level.

The aim of the study was to analyze and assess the possibility of using a two-stage filtration system with ceramic membranes: a 3-tube module with 1.0 kDa cut-off (1st stage) and a one-tube module with 0.45 kDa cut-off (2nd stage) for treating effluent water from a juvenile African catfish aquaculture. The study revealed that during the 1st filtration stage of the effluent water, the highest degrees of retention were obtained with respect to: suspended solids SS (rejection coefficient RI=100%), turbidity (RI=99.40%), total iron (RI=89.20%), BOD5 (RI=76.0%), nitrite nitrogen (RI=62.30%), and CODCr (RI=41.74%). The 2nd filtration stage resulted in a lower reduction degree of the tested indicators in comparison to the 1st filtration stage. At the 2nd stage, the highest values of the rejection coefficient were noted in for the total iron content (RIV=100%), CODCr (RIV=59.52%; RV=64.28%, RVI=63.49%) and turbidity (RIV and RV = 45.0%, RVI=50.0%). The obtained results indicate that ceramic membranes (with 1.0 and 0.45 kDa cut-offs) may be used in recirculation aquaculture systems as one of the stages of effluent water treatment.