Pilot demonstration of a Novel In Situ Technology for Simultaneous Contaminant Degradation and Immobilization in Groundwater and Soil

Arsenic (As) and polycyclic aromatic hydrocarbons (PAH) were used in Sweden for decades in wood preservatives, leading to severe soil and groundwater contamination. Remediation of such areas is complex and costly, often conflicting with principles of sustainable resource use, while effective in situ techniques are lacking. In this project, we propose an entirely new approach to soil remediation, immobilizing As and degrading PAH without soil excavation through electricity-induced processes. The project aims to demonstrate the method on a pilot-scale and assess its impact on the environment, resource and energy consumption, and overall sustainability. The project comprises collaboration between owner of contaminated areas Trafikverket, environmental consultant Afry, and LTU researchers specializing in soil remediation and electronic systems. The outcome of this project will contribute to long-term protection of groundwater resources, ensuring safer water and healthier ecosystems in Sweden and potentially in other regions facing similar contamination challenges.

Old wood impregnation plants have left behind serious contamination in the soil and groundwater in Sweden. Two particularly problematic substances are arsenic (As) and polycyclic aromatic hydrocarbons (PAH), which are both dangerous to humans and the environment. Although the use of these substances has been banned, they remain in the soil and can slowly leach into the groundwater. Digging up and disposing of contaminated soil is currently the most common method, but it is expensive, energy-intensive and creates large amounts of waste. At the same time, there is a risk of spreading the contaminants further during handling.

This project tests a completely new and sustainable method for remediating contaminated soil – directly on site, without digging. By using electricity to control how iron moves in the soil, we can both break down organic contaminants (PAH) and bind the arsenic so that it is no longer mobile or dangerous. The iron comes from degradable electrodes in the soil and forms reactive substances that capture the arsenic. At the same time, the PAH is broken down through electrochemical reactions.

The aim of the project is to demonstrate a new method for in situ remediation that simultaneously reduces the soil's toxicity and prevents the further spread of contaminants to groundwater. It is about creating an effective, sustainable and energy-efficient technology for dealing with complex contaminated areas - especially where traditional excavation is not possible or desirable.

The method combines new technology in electronics and environmental science. It has already been successfully tested in the lab, and now we are taking the next step: a pilot trial in the field at a contaminated site that is still used for industrial activities. This means that we can test the technology in a real environment without disturbing existing infrastructure, which is a major advantage. The project is run by researchers at Luleå University of Technology together with the Swedish Transport Administration and the environmental consultancy firm AFRY.

In addition to reducing environmental and health risks, the method can also save both resources and emissions. By avoiding transport and landfill, the climate impact is reduced – something that is completely in line with the circular economy and sustainable development. The technology has the potential to be applied in other places in Sweden and internationally, where similar pollution problems exist.

This project belongs to Forma's priority area "Sea and Water", with a particular focus on groundwater protection and pollution control. By developing integrated solutions for soil and water purification, the project addresses the urgent need for long-term groundwater protection in Sweden.

By linking remediation and groundwater protection in one and the same system, a comprehensive solution is created for the environmental work of the future. In the long term, it contributes to healthier ecosystems, safer drinking water and new opportunities for reusing land that is currently unusable due to pollution.

This project is funded by Formas under project number 2025-01366.