Life-Cycle Burden Shifting in Solvent-Based Regeneration of PFOS-Laden Granular Activated Carbon.

Granular activated carbon (GAC) is widely used to remove perfluorooctane sulfonate (PFOS) from contaminated water, yet its sustainable regeneration remains challenging. Solvent-based regeneration preserves the carbon matrix but may shift environmental burdens toward solvent production, chemical use, energy demand, and downstream waste management. Here we present a life cycle assessment (LCA) of PFOS-laden GAC regeneration using deionized water (GAC-WR) and ethanol (GAC-ER). We identify electricity-driven elution and downstream incineration as the dominant environmental hotspots across 18 midpoint impact categories. Selected chemical-assisted configurations (NaOH-modified water and HCl-modified ethanol) improved regeneration efficiency and reduced environmental impacts under the evaluated conditions by reducing virgin GAC supplementation. An industrial-scale model incorporating equipment upscaling and thermal integration further mitigated laboratory-specific energy overestimation. Compared with the corresponding baseline scenarios using the global electricity mix, hydropower-based electricity reduces global warming potential to 3.30 and 8.26 kg CO2e kg-1 for GAC-WR and GAC-ER, respectively, while increasing life-cycle water consumption to 230% and 266% of the respective baselines. This cross-category burden shift demonstrates that reducing climate impacts does not necessarily reduce the broader life-cycle environmental footprint. Overall, sustainable solvent-based GAC regeneration requires balancing regeneration efficiency, energy supply, chemical inputs, solvent recovery, and management of PFAS-containing wastes.