From Sand to Sludge: The Fight Against Forever Chemicals for a Cleaner Future An Investigation into the Removal of PFAS from Water

Per- and polyfluoroalkyl substances (PFAS), often called “forever chemicals,” are highly persistent compounds widely used in industrial and consumer products. Their resistance to degradation, caused by the strong carbon–fluorine bond, enables accumulation in the environment and living organisms, raising concerns about ecological and human health impacts. Consequently, effective PFAS remediation technologies are increasingly needed. The ultimate goal is to develop a cost-effective and practical technique to remove these chemicals that could be used widely and integrate into the existing treatment techniques. This study evaluated three PFAS remediation approaches: coated sand filtration, biological treatment using sewage sludge, and chemical solvent treatment. The aim was to assess their effectiveness and identify the underlying removal mechanisms. Batch adsorption experiments showed that sand coated with cationic polymers, particularly chitosan and polyDADMAC, enhanced PFAS removal compared to uncoated sand, especially for long-chain compounds such as PFOS and PFOA. However, a subsequent column filtration experiment demonstrated limited removal under continuous-flow conditions. Biological treatment with aerobic and anaerobic sewage sludge resulted in substantial PFAS removal, particularly for longer-chain PFAS. Comparisons between active and
inactive sludge indicated that adsorption was the primary removal mechanism, although anaerobic microorganisms may also have contributed to PFAS uptake. Chemical treatment using acetonitrile (ACN) and ethanol (EtOH) was largely ineffective, reflecting the high stability of PFAS. An exception was GenX, which showed a notable concentration decrease in ACN, suggesting that some PFAS structures may be more
susceptible to chemical modification. Overall, adsorption-based methods, particularly coated sand and sewage sludge treatment, showed the greatest potential for PFAS removal, while chemical degradation remained challenging. The results highlight the importance of contact time, PFAS chain length, and treatment conditions in determining removal efficiency. Future research should focus on optimizing filtration systems, clarifying microbial contributions to PFAS remediation, and distinguishing degradation from adsorption processes.