The wastewater treatment plant (WWTP) of Vigo is the main source of microplastic particles in the estuary, according to an article published in Marine Pollution Bulletin by researchers from CESAM/DFis (Portugal), in collaboration with the EphysLab team from the Marine Research Center of the University of Vigo. The study, available on the ScienceDirect platform, aims to determine what percentage of these contaminants remains in the estuary and how much disperses into the open sea. To achieve this, researchers carried out different simulations to understand how wind and tides affect microplastic concentrations in the Vigo estuary.
The research concludes that the areas of Canido and Samil are the most exposed to these contaminants, since the Lagares WWTP acts as the main entry point of microplastics into the estuary. These particles, smaller than five millimeters and invisible to the naked eye, degrade the environment and accumulate in living organisms, including humans. In fact, several scientific studies warn that they may cause serious health effects. Researchers also indicated that, during the study, “half a million particles were instantly released at the surface” from the Lagares WWTP.
Normally, treated water from the Vigo WWTP is discharged near the seabed through a submarine outfall. However, in the case of microplastics, the behavior is different, as they do not remain on the bottom: “they rapidly rise through the water column and reach the surface within a few minutes (between 4 and 9 minutes),” they explain.
The study also highlights that wind strength “exerts a dominant influence on the fate and dynamics of floating microplastics in the Vigo estuary.” Thus, strong winds, combined with upwelling events and neap tides, favor the transport of most microplastics toward the continental shelf (open sea). In contrast, during spring tides, contaminants tend to concentrate in coastal areas, especially in Samil and Canido. Under these conditions, researchers conclude that up to 40% of the emitted particles may remain trapped in the area.
The researchers conclude that these results demonstrate “the importance of considering atmospheric variability when defining effective management strategies for the region.” Likewise, they emphasize that their work highlights “the need to integrate these processes into wastewater management practices to improve monitoring and mitigate microplastic pollution from treatment plants.”
Original news and photograph: La Voz de Galicia, 26 March 2026