Removal of perfluorinated compounds from industrial water effluents. A pilot technology Sergio Manzetti, Fjordforsk A/S Midtun, 6894 Vangsnes. www.fjordforsk.no

Perfluorinated compounds Perfluorinated compounds are a highly stable family of chemical compounds use for coating, flame-retardation and physical stabilization of materials(Manzetti et al, 2014). Perfluorinated compounds are on the list of priority pollutants to remove from fabrication and industrial production cycles, given their bioaccumulating potential in living organisms. All major continents and countries are exposed to PFC contamination in soil and groundwater, particularly, USA, China, India and Europe. Norway is the first country to impose a maximum level of PFC allowed in exposed soils. PFC are planned to be discontinued from the industry and be replaced by other more bio-friendly materials, such as degradable nanomaterials and polymers.

Elimination methods PFCs are difficult to remove from soil, water and other phases, as they do not undergo chemical reactions easily given their organofluorine bonds. PFCs are neither water-soluble or oil-soluble, and present therefore a challenge in purification methods. Active carbon has been used to filter PFCs from water, however some studies show low efficacy(40-50% removal rate), while others show good sorption[2]. Active carbon is however limited in that it cannot easily be removed from water after purification and is poorly compatible with soil- purification approaches. Other studies show that active carbon can be used as a stationary matrix for binding PFCs[3]. Active carbon has the disadvantage in that it does not induce catalysis or chemical reactions that decompose the PFCs.

Using Norwegian mineral nanoparticles to remove PFCs from water/soil A pilot study developed since 2014 shows that a combination of a mineral from Norway in nanoparticle form, produced at a low cost, can be an efficient mode of binding and expectedly catalyzing PFC- degradation. Removal rates reach 98% for the heaviest PFCs. Minimum removal rates of 35% for short-chained PFCs (Pentafluoro- variants). The method is scalable and requires engineering and fabrication for testing. The method is applicable for water and soil purification of PFCs.

Purification performance from contaminated water. Click to add text Far left column shows 21 different purification runs, delineated by concentration changes in each following column towards the right. For instance, in 1 liter sample purified a concentration change of PFOS from before (51.4 ppb) to after (3.1 ppb) results with the given method.

How the technology works Industrial water effluent containing PFCs, with alkyl groups, sulphonic groups, up to gram/liter quantities, dispersed, solubilized or colloided in water. - Method is scalable. - PFCs not the only pollutant that can be removed. - Mineral nanoparticles may be re-used before discard. - Mineral nanoparticles has to be discarded as chemical waste(to municipal reception) after use(x-cycles). - Effluent water is highly purified, but may contain residual small fragments of PFCs which are more degradable and less hazardous to the environment. - Critical parts of the filter/column system require replacement after x-runs. Purification procedure(with potential of re-cycliing)

References 1. Manzetti, S., van der Spoel, E. R., & van der Spoel, D. (2014). Chemical properties, environmental fate, and degradation of seven classes of pollutants. Chemical research in toxicology, 27(5), 713-737. 2. Ochoa-Herrera, V., & Sierra-Alvarez, R. (2008). Removal of perfluorinated surfactants by sorption onto granular activated carbon, zeolite and sludge. Chemosphere, 72(10), 1588-1593. 3. Yu, Q., Zhang, R., Deng, S., Huang, J., & Yu, G. (2009). Sorption of perfluorooctane sulfonate and perfluorooctanoate on activated carbons and resin: kinetic and isotherm study. Water Research, 43(4), 1150-1158.