On June 28th, 2024, Shimizu Construction Co., Ltd., led by President Kazuyuki Inoue, conducted indoor purification tests using our company's unique soil washing technology on contaminated soil containing perfluorinated compounds (PFAS), harmful substances to the human body that have been identified, targeting actual contaminated soil collected within the United States, and confirmed that about 99% of PFAS content can be removed from the soil. This purification test has been conducted since June 2023 in Texas, USA, in collaboration with Los Alamos Technical Associates, Inc, an engineering company in the United States, and Amarillo College, and this test result demonstrates the effectiveness of our cleaning technology for PFAS contaminated soil. In the future, we plan to build a small plant in the United States and work on the technological verification on a plant scale.
PFAS is an artificial compound that has the properties of a surfactant that combines hydrophilic and hydrophobic groups, and has the unique characteristic of being resistant to heat and repelling both water and oil. Therefore, it has been used in a wide range of products, such as coating agents and foam fire extinguishers. On the other hand, PFAS is also known as the "forever chemical" due to its resistance to decomposition in the natural environment, which has raised concerns about its residual and accumulative effects on the environment and living organisms, resulting in regulations such as bans on manufacturing, exportation, and use, as well as setting water quality management targets for tap water and other measures in countries around the world.
Especially in the United States, which is leading the way in regulation, PFOS (perfluorooctanesulfonic acid) and PFOA (perfluorooctanoic acid), typical substances of PFAS, were designated as target substances under the Superfund Law, which established the principle of responsibility for cleaning up pollution caused by hazardous substances, in April 2024, making the need for cleaning up PFAS contaminated soil a pressing issue.
Our soil washing technology, which we have, combines a classification method that aggregates pollutants into fine particles of soil with a foam separation method (flotation) that attaches contaminated particles to the surface of foam in water and separates and recovers them, maximizing the purification quality of the cleaned soil. The cleaned soil can be reused for burial, etc., reducing soil treatment costs as it greatly reduces the volume of concentrated polluted soil that requires secondary treatment such as incineration.
Since the need for cleaning up PFAS contaminated soil has become apparent from fiscal 2021, we have been developing PFAS decontamination technology using our own soil washing technology. In the indoor purification test using actual contaminated soil this time, we succeeded in removing about 99% of PFAS content from the soil and confirmed that about 99% of the residual PFAS in the washing water can also be removed.
In the future, we aim to expand our PFAS contaminated soil decontamination business in Japan by demonstrating the processing performance on a plant scale through purification tests in small-scale plants, accumulating processing achievements in the US market.
In the future, we aim to demonstrate the processing performance at plant scale through purification tests in small-scale plants, accumulate processing results in the US market, and eventually expand the PFAS-contaminated soil remediation business in Japan.
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Indoor purification test of PFAS contaminated soil in the United States
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