Microplastics filtered by sewage treatment plants re-enter the environment through soil fertilizers.
This is the main conclusion of a research team of TecnATox, led by Dr. Joaquim Rovira
and Dr. Nora Expósito
, who analyzed several samples of water and sludge from different units at a wastewater treatment plant. The results showed that, although 96% of the microplastics disappear from the treated water, these are deposited in the sewage sludge, which is often used as fertilizer in agriculture and can pose significant risks to to health and ecosystems.
In every kilogram of sludge, the researchers estimated an approximate amount of 100,000 microplastics.
As they highlighted, "these particles can help to accumulate and transport heavy metals and other chemical pollutants, thus increasing environmental and human health risks". In addition, "microplastics can be ingested by terrestrial microorganisms and enter our food chain".
Pollution by microplastics is a global environmental problem, present in all natural ecosystems (water, soil and air) and which concerns not only the scientific community, but also society in general. Microplastics are non-biodegradable synthetic particles with a diameter of less than 5 mm, which can enter natural ecosystems in several ways, one of the main ways being water treatment plants.
More information from this study can be found at the following scientific paper:
Lara Dronjak, Nora Exposito, Jordi Sierra, Marta Schuhmacher, Karin Florencio, Beatriz Corzo, Joaquim Rovira, Tracing the fate of microplastic in wastewater treatment plant: A multi-stage analysis of treatment units and sludge
, Environmental Pollution, Volume 333, 2023,122072, ISSN 0269-7491, https://doi.org/10.1016/j.envpol.2023.122072
TV3, the Catalan public television, echoed this news at TN Comarques: https://www.ccma.cat/tv3/alacarta/telenoticies-comarques/un-estudi-de-la-urv-questiona-el-tractament-dels-microplastics-a-les-depuradores/video/6244264/