By Nick
Lavars
May 08, 2022
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A new study has found that fertilizer made from sewage sludge and used widely in agriculture operations is introducing vast amounts of microplastics into Europe's soils Photo credit: Depositphotos
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Sewage sludge serves as an appealing and sustainable source
of fertilizer, for both large-scale agriculture operations and home gardeners.
But studies are starting to illustrate that its contents may not be entirely
benign, neither for the environment or living organisms.
A study published last year that analyzed home
fertilizer products found unsafe levels of toxic PFAS "forever
chemicals" in every sample. That research found that typical sewage
treatment methods don't break down these persistent chemicals, and as sludge is
widely applied to lands across the US, it introduces huge amounts of them to
food crops and waterways.
This new study was carried out by scientists at Cardiff
University and the University of Manchester and focused on the farmlands of
Europe, and the risks posed to them by fertilizers made from sewage sludge. The
work involved analyzing samples from a wastewater plant in Newport, South
Wales, which treats sewage from a population of around 300,000.
This showed that the plant was collecting larger plastic
particles between 1 and 5 mm in size with a 100-percent strike rate,
preventing them from slipping through into the waterways. Each gram of the
sewage sludge created through this process, however, was then found to contain
up to 24 microplastic particles, amounting to around one percent of its total
weight.
The scientists then extrapolated on this by using data on
the use of sewage sludge as a fertilizer across the continent from the European
Commission and Eurostat. This indicated that somewhere between 31,000 and
42,000 tonnes of microplastics, or many trillions of particles, are being
applied to the soils of Europe each year. According to the authors, this rivals
the concentration of microplastics in the surface waters of the ocean.
“Our research questions whether microplastics are in fact
being removed at wastewater treatment plants at all, or are effectively being
shifted around the environment,” said lead author of the study James Lofty,
from Cardiff University’s School of Engineering. “A clear lack of strategy from
water companies to manage microplastics in sewage sludge means these
contaminants are transported back into the soil and will eventually return to
the aquatic environment.”
The findings offer new insights into the way microplastics
migrate around the environment, but perhaps aren't all that surprising in light
of recent research in the area. A 2018 study found microplastics in human
stool samples all around the world, and we've also seen scientists discover
plastic particles in the human
bloodstream and deep
in the lungs for the first time. Other research has demonstrated how
microplastics in wastewater treatment plants can foster
the growth of superbugs, and how they can carry
dangerous pathogens far out to sea.
“Our results highlight the magnitude of the problem across
European soils and suggest that the practice of spreading sludge on
agricultural land could potentially make them one of the largest global
reservoirs of microplastic pollution,” said Lofty. “At present, there is
currently no European legislation that limits or controls microplastic input
into recycled sewage sludge based on the loads and toxicity of microplastic
exposure."
The research was published in the journal Environmental Pollution.
Source: Cardiff University