Earthworms can help clean up the environment

Scientists from the Warsaw University of Technology (WUT) believe that the use of certain species of earthworms can be a cheap and effective method for cleaning up soils contaminated with crude oil, including the most polluted ones, such as those in Kuwait.

For cultivation in soils contaminated as a result of an oil spill, scientists from Warsaw University of Technology used a mix of the earthworm species Eisenia andrei/Eisenia fetida.

"We observed that earthworms are able to survive in such an unfavorable environment, and the final results of the content of petroleum derivatives indicated intensive biodegradation processes," Prof. Małgorzata Kacprzak, PhD, DSc, Eng., from the Faculty of Civil Engineering, Mechanics and Petrochemistry of the Warsaw University of Technology, told the Science in Poland Service.

She explained that earthworms are used in environmental biotechnology, primarily for vermicomposting processes. Vermicomposting is the most natural process for composting organic waste – thanks to the work of selected species of earthworms. These so-called composting earthworms are commercially available and can be safely used even in a home composter.

Using earthworms to clean soil, however, is a different story. Earthworms are capable of accumulating metals in their bodies. A scientist from Warsaw University of Technology conducted research on how earthworms remove metals from contaminated soils in collaboration with the University of Lille (France).

"Earthworms act as natural soil engineers. Their physical activity and gut microflora support the biodegradation of organic pollutants, including petroleum hydrocarbons," emphasized Professor Kacprzak.

As the scientist explained, when it comes to oil contamination, earthworms' role is more related to soil aeration, which directly translates into increased bacterial decomposition of pollutants. She noted that the role of the earthworm microbiome is rather minor here.

Scientists from Warsaw University of Technology believe the method is attractive because it is relatively inexpensive and does not require complex equipment. "It's a promising path towards sustainable environmental cleanup," said Professor Kacprzak.

Research was conducted, among other things, on heavily contaminated soils in Kuwait, in collaboration with one of Poland's leading companies specializing in soil remediation technologies. In 1991, during Operation Desert Storm, 10 million tons of crude oil seeped into Kuwait's soil, contaminating a significant area of ​​the country. Despite the passage of time, remediation work continues on an unprecedented scale – the area requiring remediation is approximately 300 square kilometers.

"This is the largest environmental cleanup operation inland, with an estimated value of approximately USD 3 billion," reads PW's information.

Scientists were curious whether it would be possible to introduce earthworms into such soils, as they are highly polluted and too dry, with little organic matter. "This is obviously a challenge for the earthworms. However, the preliminary results are very promising," said Professor Kacprzak.

The researcher emphasized that earthworms have a chance to make a difference in the fight against environmental pollution and the revitalization of industrial areas, because they play an extremely important role in the environment.

In her opinion, however, biotechnological enhancement of their potential is needed. "Possible directions include supporting earthworms with appropriate symbiotic microorganisms, engineering the earthworm gut microbiome to better degrade petroleum compounds, pesticides, or phenols, or genetic selection or modification that increases the ability to immobilize heavy metals," she said.

She added that, under controlled conditions, special "soil bioreactors" with earthworms could be used to purify soil from contaminated areas. "However, methods would need to be developed that would allow for the introduction of earthworms in controlled numbers and monitor the effects (to avoid disrupting local ecosystems)," the scientist emphasized.

Anna Mikołajczyk-Kłębek, Science in Poland (PAP)

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