A novel method for PFAS removal in water for human use
Ubaldini A., Rizzo A., Telloli C., Lo Meo S.
Poster Conferenza Internazionale con referaggio
Industrial society requires an ability to treat waste water or generally with the presence of pollutants and the ability of doing it in a profitable way is an important environmental and technological challenge, which requires a combination of multiple processes, chemical, physical and biological. There are different methods of purification, depending on the nature of the contaminants present in the waters, however they are often very expensive and in many cases lead to the production of sewage sludge, which can be special waste and in turn need further specific treatments. Without prejudice to the absolute need to reduce pollutants before the reintroduction of water in the cycle, it is clear that the possibility of reducing the costs necessary to make them safe is an aspect of sure interest for companies that deal with remediation procedures and represents a significant savings of public money In any case, the reduction of pollutants upstream of the reintroduction of water in the cycle remains a fundamental requirement of all processes, but it is clear that the possibility of reducing the costs necessary to make high the quality of water leaving the treatments is an aspect of sure interest for companies that deal with reclamation procedures and represent a significant saving of public money. In many cases, the technologies required for water purification are well established, but in the case of perfluoroalkyl substances (PFAS), traditional methods are not particularly valid due to their nature and their chemical-physical properties. In 2006, the European PERFORCE study investigated the presence of perfluoroderivatives in the waters and sediments of the major European rivers, at the end of which it turned out that the Po river had the maximum concentrations of perfluorooctanoic acid (PFOA) among all. This initial discovery was confirmed and deepened by subsequent experimental investigations in other areas of the basin. This highlights a situation of potential ecological and health risk. The Veneto Regional Council has recently imposed strict limits on the presence of these substances in surface waters intended for anthropogenic use. Therefore, private companies and public consortia involved environmental remediation operations need to reduce, if not completely eliminate, the presence of these pollutants. PFAS are organic compounds formed by an alkyl chain of various length totally fluorinated and by a hydrophilic group, generally an acid, carboxylic or sulfonic group. The most common molecules of this family are perfluorooctanoic acid (PFOA) and perfluorooctansulfonic acid (PFOS). These compounds have good surfactant properties and have been of great interest for various industrial applications since the 1950s, but unfortunately they are persistent pollutants, harmful to human health and very resistant to natural degradation. Therefore, they can persist in the environment, even for several years. They can cause tumors, changes in the endocrine system and increase the neonatal mortality rate. Unfortunately, they are easily found in surface waters, also in the Italian ones. Having an effective method of removing is extremely important. Purification techniques using ion exchange resins are often used, but they are not effective. Other technologies based on photocatalytic degradation give excellent results, but are slow, expensive and not suitable for large plants. The method proposed by the Traceability Laboratory (FSN-SICNUC TNMT) of ENEA in Bologna has the potential to be efficient for PFAS as it is able to degrade them into substances that can be more easily removed. Furthermore, this method would allow to treat even large volumes, it can also be useful for other possible contaminants and has germicidal effects. This method is based on the destruction by electrobeam plasma combined with chemical purification, it has proved, in similar cases, very efficient in the purification of waters and soils. The machines used in the field of water and wastewater treatment generally work between a few hundred keV and a few MeV. A practical limitation to be overcome for the use of these radiolytic processes is the limited penetration of the electron beams into the water, which can be a few cm or less. However, this difficulty can be overcome with a suitable design of the device to allow the irradiation, in continuous flow, of the liquids. The problem that should be solved is making sure that the entire volume of water to be treated is exposed to the beam. At the end of the process, the PFAS and any other pollutants are degraded to simpler substances, such as inorganic salts, soluble or not, simple organic compounds. They can be easily removed from the water being treated by consolidated technologies, among which the simplest and most economically advantageous is the exchange on ionic resins. This step can be considered fairly standard in surface water purification processes, with well-established know-how.
REMTECH EXPO: Emerging pollutants and diffuse pollution. Ferrara (Italy)