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

Abstract

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

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