A Belgian trial where hemp is being used to remove PFAS from soil is witnessing some significant improvements.
The trial is currently being conducted at Campus Vesta, a multidisciplinary training centre in Emblem, Ranst. Willows, hemp and enzymes are being used to remove PFAS from the soil and groundwater that was contaminated with PFAS following the use of PFAS containing fire-fighting foam for the fire brigade training courses in 2011.
PFAS are also being used in a very small quantity by some synthetic turf yarn producers.
“Worldwide, they are watching,” says Erik De Bruyn, Project Manager at C-biotech, the organisation that is conducting the study. “This plant-based remediation can really be a game changer.”
In three months, the presence of PFAS has decreased by no less than 67 percent. On the most polluted plot, the PFAS concentration has gone from 25 to 30 micrograms to 4.5 to 6 micrograms.
The hemp was so successful that two-thirds of the polluted site has now been virtually remediated. Remediation projects with industrial hemp are not new in themselves and have also been carried out in other places.
Soil additives
What makes the project at Campus Vesta unique is that for the first time, experiments were conducted with the addition of various soil additives. The aim of these additives is to accelerate the absorption of PFAS. “And that has been a great success,” says De Bruyn, the driving force behind the phytoremediation project. “The PFAS level has decreased in all 25 plots. In most plots, there is about eight times more PFAS in the hemp leaves than in the soil.”
Moreover, the PFAS are no longer so much in the soil, but mainly in the leaves or in part of the root. In most plots, there is about eight times more PFAS in the hemp leaves than in the soil. In the best performing plot, that is even 27 times more.
All contained
Another positive aspect is that the PFAS do not end up in the groundwater. Samples from half a metre deep show that the contamination remains in the top 20 centimetres of the soil and that nothing changes in the groundwater. This means that the PFAS cannot have been washed away either.
At the start of the project, one in four contaminated plots at Campus Vesta was below the Flemish remediation standard of 3.8 micrograms. Now, two-thirds are already below that legal standard. The fact that this has already happened in one cultivation cycle is spectacular.
The secret lies in the interaction between the plant and a specific soil additive. “This pilot project is a milestone for our province,” says Deputy Jinnih Beels, responsible for Campus Vesta. “It shows how innovative techniques can sustainably restore contaminated soils.”