Case: BTEX

BTEX remediation with sulfate injection

Location: Former industrial site, Belgium
Contamination: BTEX in groundwater
Area: ± 3,000 m²
Depth: Up to 20 meters
Period: 2017-2024
Status: Closure document delivered by OVAM

About this project:

A former industrial site was facing severe groundwater contamination with BTEX, caused by historical underground solvent storage. After the demolition of buildings and tanks and conventional remediation of the unsaturated zone, persistent contamination remained in the groundwater. A previous remediation attempt with biosparging failed due to the poor permeability of the soil.

Sodecon proposed an alternative technique: the injection of sulfate to stimulate sulfate-reducing bacteria in the soil. Although these bacteria work more slowly than aerobic bacteria, sulfate is ideal for poorly permeable soils:

It can be injected at high concentrations
It remains active in the soil for extended periods
It stimulates long-term biodegradation

Results:

A successful pilot test was conducted in 2017
Large-scale remediation began in 2019 with 160 injection wells
In 2020, the first sulfate injection was performed, with marked decreases in BTEX concentrations
A second injection followed in 2022 on 40 wells
Increased microbial activity remained noticeable up to 4 years after injection
In March 2024, remediation was officially completed with a Closure document from OVAM

Thanks to this innovative approach, the site is once again ready for industrial development. Moreover, biodegradation continues actively even after the remediation process has been completed, ensuring long-term effectiveness.