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

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
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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.