Remediating the forever chemicals in soil and water
From US drinking water to the soil in Europe and even the Arctic snow. More and more info is surfacing on the alarming levels of PFAS chemicals in our environment. Consequently, many public and private organisations have come to realise that they own toxic land. And the matter becomes even more pressing when they have civil engineering or marine projects in mind. How do we handle enormous volumes of polluted soil without putting public health in danger? Our environmental department worked out an effective solution – which is more circular than you’d think.
Facts about PFAS
- PFAS – the acronym for per- and polyfluoroalkyl substances – is a collective name for over 4,000 chemicals. PFOS and PFOA are the most used and know.
- High levels of PFAS can lead to severe health conditions, such as decreased fertility, increased risk of some cancers and higher cholesterol levels.
- PFAS are called ‘forever chemicals’ because their carbon-fluorine bond is one of the strongest ever created in organic chemistry. This gives them the unique properties of being resistant to heat, moisture and stains. Very useful for our daily activities – but less so for its degradability.
Fighting the good fight
Since 2016, we have been testing several techniques to remediate PFAS, both in soil and water. The results of innovative and more tradition techniques all lead to the same best-practice – soil washing. This technique consists of a series of washing and separation processes. Over 80% of an average polluted soil is turned into PFAS-free coarse sand. This can be reused in various civil applications. The PFAS fine fraction is dewatered and afterwards disposed of. The process water is first reused for numerous washing cycles, after which it gets completely purified and released in the environment. Only the contaminated fine fraction – which is less than 20% for an average soil – needs to be processed further.
Emma Vanderveken, Project Engineer R&D
One of those techniques, is immobilisation. Here, we prevent PFAS from spreading to groundwater. Another is soil flushing – a technique where we extract PFAS from the soil by flushing it repeatedly with water and biodegradable additives. Both techniques can be done on site, reducing our carbon footprint and optimising cost-effectiveness.
To reduce PFAS concentrations in process water and groundwater, we are investigating foaming. PFAS is thereby attracted to a foam and separated from the main water stream. However, the ultimate goal remains to destroy PFAS and break its organic bond. An optimised destruction technique therefore holds an important place in our research. While some of these techniques are still in research phase, others are now being rolled out in pilot projects.
Discover how
