GOALS

The general objective of the Frac-In-Ox Eurostars project is the development of a soil remediation technology for applying oxidative biological and chemical remediation concepts at sites where the subsoil is poorly or limitedly permeable. This project ran from March 2021 until February 2024.

The technological concept builds on the Frac-in technology successfully developed within a recently concluded Eurostars project. The Frac-in technology is already capable of facilitating reductive remediation concepts at impermeable sites by controlled application and filling of permeable, reactive fractures in the subsoil. However, the technology was developed for applying reductive remediation concepts: stimulated anaerobic bioremediation and in situ chemical reduction. Consequently, the technology is currently incompatible with oxidative concepts: stimulated aerobic bioremediation and in situ chemical oxidation.

Two main achievements are necessary to obtain a version of the Frac-in technology compatible with oxidative remediation concepts.

• Objective 1: Development of a slurry that contains both oxidative properties (for reactivity) and proppant material (for the permeability of the fractures).

• Objective 2: Development of a mixing and injection setup capable of creating and injecting the slurry under field conditions.

For Objective 1, the challenges and risks are mainly related to the combination of a gelling agent (necessary to make the slurry manageable) and oxidative reagents. Current gelling agents are organic carbon compounds, which are broken down by oxidative reagents. Various approaches will be investigated: a) the development of a slurry with gelling agents that do not or only slightly react with oxidants, and b) the development of a 'phased' slurry, where the oxidants come into contact with the slurry only during injection.

For Objective 2, the challenges and risks are mainly related to developing a mixing and injection setup compatible with the developments of Objective 1. An important element here is managing the corrosive effects related to the oxidative components: this can be addressed through further developments in the materials used as well as in the operational methods.

PROject outcomes

The successful development of the Frac-In-Ox remediation technology will represent a significant added value to the range of remediation techniques that we can offer. The Frac-In-Ox technology targets a specific contamination issue for which there are often no efficient, very costly, or unsustainable solutions currently available.