Efecte de les nanopartícules metàl·liques en presència de diferents tipus de (micro)plàstics sobre la Daphnia magna, usada en els tractaments terciaris d’aigües Residuals

Freshwater scarcity represents an increasingly urgent global challenge, requiring efficient strategies to ensure safe water access, such as wastewater reuse. In this context, recent regulations establish standards to minimize contaminants in treated water, including emerging contaminants such as microplastics (MPs), which are increasingly present in the aquatic environment. For this reason, it is necessary to improve existing wastewater treatments to reduce this type of contaminants. Daphnia magna (D. magna) is a filter-feeding crustacean with the capacity to remove microscopic particles and bacteria. Its use as a biofilter may represent a sustainable alternative to conventional wastewater treatments. In this work, the capacity of D. magna to remove silver nanoparticles (AgNPs) from water in the presence and absence of different types of MPs has been studied. AgNPs have been chosen because they are widely used for their antimicrobial properties, and MPs have been selected because they can adsorb other pollutants, in addition to their persistence in the environment. First, various parameters have been tested to ensure good stability of the AgNPs during the experiments. Then, experiments have been carried out with D. magna to evaluate its efficiency for removing AgNPs in the presence and absence of MPs of different materials, aging times and origin. The effect of the type of water (mineral and wastewater) has also been tested. The results of the stability studies have shown that AgNPs are stable in plastic material and in media containing 4 mg·kg-1 of humic acids and 0.01% of surfactant. The data obtained in the studies evaluating the potential of D. magna to remove AgNPs from water indicate that these organisms accumulate much more AgNPs in the presence of MPs from everyday products than in the presence of commercial MPs. With respect to the type of MP material, it has generally been observed that these organisms ingest AgNPs similarly in the presence of polyethylene and polystyrene MPs. Tests with different waters have shown no differences in the accumulation of silver in D. magna. Finally, the survival of D. magna has been seen to be one of the critical factors since after 48h many of these individuals had died