Treatment technologies for removal of per- and polyfluoroalkyl substances (PFAS) in biosolids

Abstract

PFAS (per- and polyfluoroalkyl substances) possess hydrophobic and hydrophilic characteristics, recalcitrant nature due to a strong C-F bond, and have the potential to endure adverse environmental situations and greater surface activity. Biosolids are the side-resultant in the sludge treatment process, which are primarily applied as soil conditioners. These PFAS have been detected at an abnormal level in biosolids and through various routes retained in the human and animal systems. However, for PFAS, in-depth consideration of physical and chemical properties and exposure pathways is still limited, ultimately curbing the development of new technologies which pave the trails for PFAS destruction. Several attempts have been carried out using the biological approach, and hydrolytic methods, but the carbon–fluorine bond being resistant to these approaches limits them. Therefore, impactful end-of-life technologies are required for PFAS remediation in biosolids. The current review provides new insights into PFAS destruction technologies. Different emerging PFAS destruction technologies such as incineration, hydrothermal liquefaction, pyrolysis, thermal hydrolysis, supercritical water oxidation, and several other processes, their latest advancements and limitations have been discussed in detail in this current study. Classification of PFAS, exposure of PFAS to the environment and human exposure, ways in which humans can avoid PFAS, and different detection techniques for PFAS analysis along with their merits and demerits have been broadly discussed in this review. The mechanism of PFAS degradation during thermal processes has also been covered.