Removing PFAS from the soil/groundwater with the aid of plants: it proves to be a promising technology for the future. TAUW investigated the possibilities of phytoremediation and concluded that this technology can become an effective and sustainable alternative for the current PFAS remediation methods, which are often complex, costly and can be a burden for other environmental compartments.
Removing PFAS from the soil/groundwater is a challenging problem. At present, there are only a limited number of effective, cost-efficient technologies suitable for full-scale applications. In addition, the existing technologies often have limitations, such as the matrix (soil/groundwater/sludge) that can be treated. The soil type (sand/clay) is sometimes also limiting. Many of the currently applicable technologies are also not sustainable, as they do not completely destroy PFAS to unharmful substances, produce large volumes of waste products that must be disposed of, or consume huge amounts of energy.
TAUW is continuously searching for innovative and sustainable technologies that make sustainable and future-proof remediation of PFAS possible. A great example of a sustainable technology that we are already using at full scale is the PFAS soil washing method. Alongside this method, which has already been proven very suitable for ex-situ treatment of sandy soils, we have searched for nature based methods of removing PFAS from the soil, preferably without the need for excavation. This led us to phytoremediation, a proven in-situ method that uses plants to remove contamination from the soil and/or groundwater. We investigated the potential of this method for removing PFAS, which turns out to be considerable. Wageningen University graduate Odeke Koning concluded that phytoremediation can become not just technically possible, but also an economically viable method for sustainable treatment of soils/groundwater contaminated with PFAS.
In this study, various plant species were identified that are capable of extracting large amounts of PFAS from the soil/groundwater (hyperaccumulation). Particularly in situations involving larger areas where more time is available, phytoremediation (possibly combined with other methods) can be a (cost-)effective approach for managing/containment of PFAS contamination. From literature, we identified various factors and circumstances that influence the effectiveness of phytoremediation of PFAS. From lab experiments and field studies carried out factors were identified that affect the effectiveness of phytoremediation. It was concluded that factors like water availability, organic matter content and the functional group of the PFAS we significant. This is because these factors affect the bioavailability, translocation and bioaccumulation of PFAS in various plant species.
Phytoremediation has potential as a nature based solution to extract PFAS contamination from soil, and groundwater but it is not yet applied on full scale. This is because the technology has only been subjected to limited lab/fieldtesting, which means for instance that it is still difficult to estimate how long it will take to effectively remediate a contaminated location. Due to phytoremediation , PFAS is stored in various parts of plants (phytoextraction). However, it appears that it is not destroyed by the plants themselves. This could lead to undesirable further migration of the contamination in the ecosystem (bioaccumulation/biomagnification). Ideally, PFAS would be completely broken down in the plant system, which for other organic contaminants has be proven to be able to transform/degrade complex organic compounds biologically. Bacterial strains have already been found that can transform PFAS, but the decomposition process is slow, only occurs under very specific conditions and often does not lead to completely harmless endproducts. To completely remove PFAS from the environment, plants/plantparts (for instance leaves) containing PFAS currently must be harvested and processed. While various technical concepts for this are available, these must be investigated further to determine their cost effectiveness etc. This means that before phytoremediation can be applied effectively, further research (lab and field studies and pilot projects) is still required.
At TAUW, we believe that phytoremediation can contribute to tackling PFAS contamination. To continue researching the feasibility and cost effectiveness of this technology, we are aiming to work in partnership with other European organisations as much as possible. This is also promoted by the EU, which challenges organisations to develop innovative solutions to protect human health, the environment and natural resources from persistent and mobile substances such as PFAS. TAUW France and TAUW Netherlands were part of the CHEMSHIELD initiative led by KU Leuven University (B) and 15 other research partners. In this context, we recently contributed to the preparation and submission of a project proposal for a research programme for the development of analytical technologies, risk assessment, chemical-physical water treatment technologies and also specific biological remediation of PFAS compounds by phytoremediation and biopiling of soil. TAUW Germany was part of the REMSHELL initiative with another consortium, which also focused on demonstrating sustainable treatment technologies for PFAS in soil and groundwater.
Alongside these European research projects, we aim to continue investigating the feasibility of using phytoremediation for PFAS and possibly other emerging contaminants. Various TAUW clients have already been approached and have agreed to submit samples for testing and demonstration locations for pilot projects. If you are interested in the phytoremediation concept and the possibilities for PFAS and other emerging substances, or wish to contribute to further research of this technology, then please contact us. We would be happy to work together.