Modelling the distribution of microplastics released by wastewater treatment plants in Ria de Vigo (NW Iberian Peninsula)

The accumulation of plastic waste in estuaries is growing due to the increase in their use in daily life and their inadequate treatment on wastewater plants (WWTPs). Hydrodynamic and particle-tracking models were validated and used to improve the knowledge about the distribution and concentration of microplastics released by WWTPs in the Ria de Vigo. Results showed that the Vigo WWTP is the main driver of microplastics to the Ria de Vigo. Besides, 21% of the released microplastics reach the adjacent ocean, 24% remain anchored around the Cies Islands, and a negligible percentage reaches the upper estuary when the emission occurs under ebb on spring tide conditions. A negligible number of released microplastics is exported to the nearby ocean when the emission occurs under neap tide conditions. This research can provide a useful tool to support the identification of monitoring processes and debris removal.

Automated summary

This research validated hydrodynamic and particle-tracking models to study the distribution of microplastics released by WWTPs in Ria de Vigo, finding that the Vigo WWTP is the main source. Results showed that most of the released microplastics either remain around the Cies Islands or reach the adjacent ocean, with only a small portion reaching the upper estuary.