Using the geotube for dehydrating slurry, France

Cleaning industrial ponds

In March 2017, REMEA handled cleaning of the main waste ponds covering 2,200m² at ArcelorMittal’s site in Fos-sur-Mer, southern France.

The extraction of the slurry was carried out using a dredging pump equipped with a protection skirt to limit the solid matter going back into suspension. After pumping and homogenisation in an agitation tank, the liquid slurry was flocculated with the aim of agglomerating the solid particles to facilitate filtering.

After flocculating, the slurry was wrung out and dehydrated in two geotubes covering an area of 250m². The filtrate from the wringing process was pumped back into the reservoir inlet after treatment in separator to capture any floating hydrocarbons.

The microfiltration membrane technology in the geotube was used to reduce the volume of the pumped slurries. As a result, of the 1800m3 of liquid slurry removed from the bottom of the ponds, only 400m3 of dried sediment was removed off-site, or less than a quarter of the initial volume.

During the process, the position of the pump was monitored in real time by a GPS system. The waste and slurry were regularly analysed on site using portable equipment to check turbidity, matter in suspension and dry matter, which was followed up by further analysis in an approved external laboratory. The volume pumped was confirmed by two depth measurements taken before and after the treatment.

The results from the analysis showed that the cleaning work in the reservoir had no impact on the quality of the waste, thus guaranteeing the respect for thresholds under the site’s local operating permit.