Ion-exchange treatment is an effective treatment technology for many problematic water pollutants. For instance, ion-exchange treatment can effectively remove per- and polyfluoroalkyl substances (PFAS) from impacted water; however, the environmental impacts associated with ion-exchange regeneration of PFAS-laden resin have not been explored. In particular, the trade-offs of altering the composition of the regeneration solution and disposing of or recycling the waste regeneration solution are not known. To fill these important gaps in the literature, this research conducted a comparative life cycle assessment (LCA) of a hypothetical ion-exchange-based PFAS remediation system with different regeneration scenarios including disposing of waste regeneration solution via incineration, reusing the organic cosolvent and brine fractions of the waste regeneration solution, and altering the composition of the regeneration solution to avoid organic cosolvent or NaCl. The results show that disposing of waste regeneration solution via incineration, without recycling organic cosolvent or brine, had the greatest environmental impact, and that incineration accounted for the greatest impact among contributing processes. Recycling of the cosolvent, or cosolvent and brine, fraction of the waste regeneration solution resulted in lower environmental impacts due to reduced mass of waste disposed of via incineration. Replacing NaCl in the brine with an alternative salt resulted in higher environmental impacts, with salts derived from chemical production, such as ammonium chloride and potassium carbonate, showing the largest increases in impacts. The results of this research highlight the insights that can be gained by conducting a LCA on ion-exchange treatment such as altering regeneration conditions and minimizing the volume of waste regeneration solution to dispose of.

Insights on ion-exchange processes and operation through life cycle assessment: Example of PFAS remediaiton by ion exchange

ACS Spring 2022

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