Environment: From ENEA a new technology application to remove PFAS from water

A team of researchers at the ENEA Bologna Center is working on a new application of the technology based on a controlled energy electron beam to remove PFAS[1] from water for civil use.

The chemical-physical action of the electron beam would allow these pollutants, highly persistent in the environment, to be degraded into substances easier to remove and, at the same time, treat large volumes of water in a very short time.

“In practice, the electron beam breaks the carbon-fluorine bond of PFAS- one of the strongest in organic chemistry- which leads to the release of fluorides, still polluting but definitely easier to treat and break down. Similar technologies for the treatment of wastewater with various types of pollutants are already in use in various parts of the world [2] and make it possible to significantly reduce the operating costs of the plants.

In the case of PFAS, this could be the only effective technique to achieve satisfactory results", explained Antonietta Rizzo, head of the ENEA Laboratory "Nuclear Methods and Techniques for Safety, Monitoring and Traceability", part of the network of the High Technology Network in Emilia-Romagna.

PFAS are widely used in everyday products like waterproof and stain-resistant clothing, fire-fighting foams and fireproof fabrics, non-stick coatings of pots and pans, packaging of microwave popcorn bags and numerous fast-foods, cosmetics, furnishing fabrics, paints, chrome plating, films that cover solar panels and also building materials such as coatings for metals and tiles. Over 4,700 types of PFAS molecules are listed in the OECD database and they all have an extremely high persistence.

"These chemicals are highly soluble in water and hardly degrade due to their chemical stability, contaminating drinking water, food and feed wherever they are used. Even if we stopped producing them immediately, they would persist in the environment for generations, considering that PFAS are the most persistent chemical substance to date, with a significant impact on surface and deep aquifers ", said Chiara Telloli of the same ENEA laboratory.

So far, conventional purification methods based on ion exchange resins or activated carbon have not proved effective. In addition to being expensive, they often generate special waste, to be treated later in suitable plants with a further cost increase and an unavoidable environmental impact. "Hence the need to study alternative technologies to be transferred to the national industry. An Italian company specializing in water purification, Tintess of Thiene (Vicenza), has already shown interest and is evaluating possible developments in the technological feasibility and sustainability of the process”, pointed out Alberto Ubaldini, researcher at the same ENEA laboratory.

In detail, the ENEA team intends to treat the water contaminated by PFAS with electronic plasmas, a technology that - using only electricity - converts water into a mixture of highly reactive chemical species[3], which perform a rapid degradation action of multiple pollutants, including PFAS, with the possibility of treating a large volume of liquids in a limited time or possibly even continuously.

“The benefits don't end there. These chemical species produced from the electron beam, although very 'aggressive', are short-lived, of the order of a few milliseconds, and do not introduce any contamination since, at the end of the process, they cannot survive in the plant. This means that no residual radiation remains in the irradiated water after the treatment. The only practical limitation is the limited penetration of electrons in water, which is a few centimeters. But a study is underway to evaluate  penetration efficiency and thickness of treatable water[4]”, explained Antonietta Rizzo.

The generation of a high voltage electron beam (or electron beam) is very advantageous and converts input energy into beam power with efficiencies up to 95% (compared to 30% obtained in UV lamps). In this way, the operating costs of the purification plants could be significantly reduced and the chemical residues, still present after the process, could be easily eliminated by well-established technologies, such as precipitation or coagulation that use simple chemical reagents added at the end of the process. "The Laboratory has recently supervised a degree thesis in energy engineering, in which theoretical evaluations of investment costs of about 14 million euro were made, showing that this type of plants offers an important economy of scale”, concluded Rizzo.

Antonietta Rizzo, ENEA – Laboratory of Nuclear Methods and Techniques for Safety, Monitoring and Traceability, 

Chiara Telloli, ENEA – Laboratory of Nuclear Methods and Techniques for Safety, Monitoring and Traceability, 

Alberto Ubaldini, ENEA – Laboratory of Nuclear Methods and Techniques for Safety, Monitoring and Traceability, 

[1] PFOS and PFOAs are considered the most representative contaminants among PFAS (or perfluoroalkyl substances), since they are the final degradation products of most fluorinated compounds and have been identified as PBT (Persistent Bioaccumulative and Toxic) substances.

[2] Oxides of sulfur and nitrogen, volatile organic compounds (VOCs), polycyclic hydrocarbons (PAHs) and dioxins.

[3] Active ions, free hydroxyl radicals, free hydrogen atoms and solvated electrons including OH-, O--, H +, HO2, O2 -, H2, O2, H2O2

[4]  The numerical simulations with Montecarlo codes are conducted by Sergio Lo Meo at the ENEA Laboratory of Nuclear Methods and Techniques for Safety, Monitoring and Traceability