PFAS: how to better clean soil from ‘forever chemicals’
Soil contaminated with harmful perfluorinated and polyfluorinated alkyl substances (PFAS) is difficult to clean, a complete remediation is often not possible.
To improve the remediation process, researchers at the University of Augsburg are trialling various cleaning methods. In order to find the best cleaning method for fine soil particles, the researchers are building a ‘soil washing machine’ on a laboratory scale. Their work is now being financially supported by the Bavarian Research Foundation.
Perfluorinated and polyfluorinated alkyl substances (PFAS) are extremely durable, water-, grease- and dirt-repellent industrial chemicals. They are found in many everyday products such as rain jackets and pizza boxes, but are also released into the environment through the production of textiles, printed matter, refrigerants, propellants and fire extinguishing foams and accumulate in soil, food and drinking water. PFAS are considered highly problematic: they are probably carcinogenic and are practically not broken down in the environment or the human organism.
If PFAS are found in the soil – e.g. when excavating soil for a construction project – it must either be cleaned or disposed of. PFAS can be removed with a special soil washing process. In this process, the contaminated soil is excavated and cleaned in a plant similar to a giant washing machine drum through targeted interaction with water.
Complete cleaning of fine-grained soils
This cleaning process already works for coarse soil fractions (sand, gravel), but the so-called fine fractions – very small soil particles with a diameter of less than 0.1 mm – are still problematic. They have to be disposed of in special landfill sites. Scientists from the Chair of Resource and Chemical Engineering (Prof. Dr Daniel Vollprecht, Samuel Griza), the Institute of Environmental Medicine and Integrative Medicine (Prof. Dr Claudia Traidl-Hoffmann, Dr Jamie Afghani), the Chair of Technology Assessment (Prof. Dr Ing. Jan Paul Lindner) and the User Centre for Materials and Environment (Dr. Timo Körner, Dr.-Ing. Christian Oblinger) at the University of Augsburg are now working together with industrial partner Züblin Umwelttechnik GmbH on a solution that enables the complete cleaning of PFAS-contaminated excavated soil.
The research project is entitled ‘Further development of soil washing for PFAS-contaminated soils with a view to recycling the fine fractions – BoReF’. As part of the project, the PFAS adhering to the fine soil particles are to be removed. The idea is to use wet-mechanical and wet-chemical processes for this purpose, for example through chemical oxidation, flotation or the use of detergent additives. To detect PFAS contamination, a new, cost-saving analysis method is being developed to characterise the large number of samples required
In order to find the best cleaning method for fine soil particles, the researchers are rebuilding the ‘soil washing machine’ on a laboratory scale.
Funding from the Bavarian Research Foundation
The BoReF project is coordinated by Prof Dr Daniel Vollprecht and is being carried out as a joint project with Züblin Umwelttechnik GmbH.
