Green filter

The Tancat de la Pipa, an artificial wetland designed as a 'green filter' for the Albufera de València, reduces microplastic pollution in the natural lagoon by 36%, according to research conducted by the Institute of Water and Environmental Engineering (IIAMA) at the Universitat Politècnica de València (UPV) and the Faculty of Environmental Sciences and Engineering at Babe?–Bolyai University in Romania.

The study indicates that the Tancat de la Pipa draws water from the Catarroja and Poyo canals to treat it and reduce the inflow of microplastics and other pollutants, which originate from rainwater runoff or from human and industrial activities such as shipping, agriculture or wastewater treatment. According to their analysis, the difference in microplastic concentrations between the inlet and outlet of the Tancat de la Pipa indicates that the wetland retains approximately 36% of the incoming microplastics.

"Vegetation and sedimentation processes retain particles, but they cannot completely prevent their transport downstream, especially in the case of the smallest particles," notes Carmen Hernández–Crespo, a researcher at the UPV's IIAMA institute and co-author of the study.

The research helps to better understand the role of constructed wetlands as a nature-based solution for mitigating microplastic pollution. "It demonstrates that a conceptual assessment of sources, combined with field observations across a series of sampling points, enables the identification of the main pathways of microplastic pollution and allows for an initial assessment of the wetland's retention performance," the researcher explains.

Optimising the design of artificial wetlands

As Carmen Hernández-Crespo explains, artificial wetlands such as the Tancat de la Pipa capture and accumulate microplastics through processes such as sedimentation, filtration and retention by vegetation. "However, the retention of microplastics should not be interpreted as a permanent removal from the environment: retained particles can be stored in sediments and organic matter, and can be remobilised by increases in flow, flooding or sediment disturbance. To optimise their retention capacity, it is important to assess their performance in terms of their design, hydrology and the characteristics of the particles."

Flooded with plasticMicroplásticos

As the research highlights, there are two categories of microplastics: primary microplastics, manufactured at a microscopic scale as raw material for larger plastics, cosmetics or cleaning products; and secondary microplastics, which result from the degradation of packaging or tyres.

The study notes that around 245 tonnes of microplastics are produced worldwide each year and end up in bodies of water, where they can be ingested and incorporated into the tissues of marine organisms. Furthermore, only 9% of discarded plastic products are recycled, meaning that the accumulation of plastics in the environment is projected to reach 3,100 million tonnes by 2050.