Active carbon deals quickly with PFOS/PFAS/PFOA
PFOS/PFAS/PFOA (perfluorinated compounds) are not really best friends with people and nature. These three components, which used to be used on a large scale including in fire extinguishing foam and industrial surfactant, are persistent organic pollutants (POPs). These are highly toxic and do not degrade once they are present in nature. This means that there is a risk that these can enter the human body via drinking water or other sources. These compounds are also present in polluted groundwater or industrial wastewater. PFOS/PFAS/PFOA are already harmful at low concentrations.
A large refinery in Northern Europe was also recently confronted with PFOS/PFAS/PFOA. This factory has expansion plans involving the initial excavation of a construction pit. During the required groundwater extraction it became apparent that the groundwater was polluted with PFOS/PFAS/PFOA. The pollutants present made it impossible to continue building works, and these first needed to be removed. The excess rainfall during the excavation works also meant that the rainwater first needed to be purified.
DESOTEC was already working for this customer. We had installed the mobile active carbon filter MOBICON 2000 for the periodic cleaning of catalyst beds that produce contaminated water. This meant we were the first point of contact for the refinery. Following careful consideration, the best choice appeared to be to use a new type of mobile active carbon filter, MOBICON 2000, as pilot system for the PFOS/PFAS/PFOA contamination. The results proved extremely positive. As a huge amount of water needed to be purified, the first system was supported by a second MOBICON-type mobile active carbon filter, with a capacity of 8.5 tonnes of active carbon.
This necessary purification required a decisive approach. The combined ground and rainwater were collected in a buffer tank, from which a flow of 50 m³/h was pumped across the mobile active carbon filter. This method enabled us to succeed in purifying the original concentration of PFOS/PFAS/PFOA (several hundred nanograms per m³) to below the detection limit. This is necessary to meet the strict discharge standards. The purification process has now been operational for several weeks and continues to deliver positive results, which means that the refinery can continue its building activities.