In partnership with Los Alamos Technical Associates (Albuquerque, NM), Shimizu Corporation (Tokyo, Japan) has begun testing soil washing technologies on per- and polyfluoroalkyl substances (PFAS) contaminated soil with proprietary and field-established techniques. Using proven soil washing techniques in a laboratory-scale test, Shimizu has recently confirmed that up to 99% of PFAS can be removed from soil and wastewater. The small-scale tests were highly effective and now field-scale testing is being planned. Lab testing has been conducted at the Amarillo College STEM Research Center in Amarillo, TX.
PFAS are a large group of synthetic compounds that exhibit both hydrophobic and hydrophilic, surfactant-like properties. They have been used in a wide variety of products, such as coatings and fire-extinguishing foam because of their heat resistance and ability to repel both water and oil. However, due to their resistance to natural degradation in the environment, concerns have been raised about their persistence and accumulation in the environment and living organisms. For these characteristics, PFAS have been dubbed “forever chemicals” and their regulations are being tightened worldwide.
The United States is one of the world-leading countries for PFAS regulation. In April 2024, the U.S. Environmental Protection Agency (EPA) released a final rule on six PFAS compounds and their Maximum Containment Levels (MCLs) in public drinking water. Public water providers have until 2027 to implement PFAS water monitoring procedures and testing. Early 2024 saw EPA add more PFAS compounds to the recognized list of chemicals as well as updated testing standards. PFAS regulation and cleanup are expected to increase as the potential for hazards to human consumption continues to grow. PFAS compounds are found to cause damage to the liver as well as adverse effects on the human immune system.
Shimizu’s soil washing technology includes particle size separation by which contaminants are concentrated, as well as flotation – a process which enhances the quality of the cleaned soil through the attachment of contaminant-bearing particles separated from the soil to the surface of air bubbles rising in water. Cleaned soil can then be reused for backfilling and other purposes. The greatest advantage of soil washing is that it reduces the amount of soil requiring further cleanup, such as incineration, resulting in lower overall treatment costs.
Shimizu has been developing PFAS-contaminated soil remediation technology since 2023 by adapting its proprietary technologies to the characteristics of PFAS. Shimizu is a world-recognized leader in soil washing, including large-scale clean-up of mineral oils, heavy metals, agrichemicals, dioxins and radiological materials. During laboratory-scale testing in the U.S., 99% of PFAS removal was achieved from both contaminated soil and soil washing process water. Moving forward, Shimizu is currently planning a small-scale field test to demonstrate the validity of its technology, followed by PFAS-contaminated soil remediation projects in the U.S, as well as in Japan.
Flotation Test
Laboratory-scale testing in progress
Laboratory-scale testing results
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