Description

The Barreiro site is a former industrial site in Portugal. For many years, industrial waste such as ash from pyrite roasting has been deposited, resulting in a complex mixture of heavy metals in the sediment and groundwater. The investigations focused primarily on arsenic and zinc. The groundwater level was approx. 2.5-3 meters below ground, had a thickness of approx. 35 meters and consisted of medium to fine sand. The groundwater velocity was 0.08-0.10 meters per day. Since no remediation target was defined by the property owner, the target for this demonstration test was to reduce the main pollutant load to 50% of the untreated values.

ColFerroX – Pilot

A pilot test (single injection well) was carried out to ensure the particle mobility and applicability in this fine-grain aquifer. Particle delivery was confirmed by taking cores 1 meter from the injection point in two different directions. The analysis of the soil sample taken from the barrier after injection showed that the iron concentrations increased from originally about 400-800 mg Fe/g sediment to about 1200-2000 mg Fe/g sediment. Therefore, it could be ensured that the injected ColFerroX™ particles were successfully precipitated near the injection site.

Results from the pilot test shows reduction in heavy metals in all wells. A case for Arsenic is shown.

For large-scale demonstration, a barrier of 22 m width was installed using 9 injection points in two rows. Normal monitoring wells were placed upstream and downstream of the barrier to record the pollutant concentrations before and after the barrier. Injection was carried out in low pressure (< 1.5 bar). A total volume of ca. 105 m3 was injected during 5 days of injection.

Results:

Reduction of all toxic metal concentrations was observed after applying the ColFerroX technology (day 0). An exemplary case for Zinc is shown where the concentrations decreased to much lower values.