(231d) Managing PFAS-Contaminated Adsorbents with a Life-Cycle Perspective

Background: Adsorbents can remove PFAS from contaminated wastewater and drinking water. These PFAS-contaminated adsorbents must be dealt with in an environmentally responsible manner. They can be disposed of in landfills, but this poses leakage risks and requires manufacturing of increasing amounts of adsorbents. Incineration can release toxic compounds and is disallowed in many regions. Options that destroy PFAS and allow for adsorbent recycling include ball milling and low-temperature incineration. In our analysis, we evaluate different PFAS destruction and adsorbent recovery options in the context of full fuel cycle energy consumption, greenhouse gas emissions, and solid waste generation to identify the options with promising environmental performance.

Methods: Using the properties and preparation methods for biomass-derived adsorbents [Ching et al., 2020], we consider three routes for PFAS disposal or destruction and, when applicable, adsorbent recovery. These include landfilling, low-temperature incineration, and ball-milling. We generate material and energy balances for these three options and develop full fuel cycle energy consumption, emissions, and waste generation using background data and calculations in the Greenhouse gases, Regulated Emissions, and Energy use in Technologies (GREET) model [Argonne National Laboratory, 2023].

Results: Per m³ of water treated, energy consumption and life-cycle greenhouse gases are nearly identical across all treatment options. This result arises because the share of energy or greenhouse gas emissions of the treatment method is less than 5% of overall impacts. For example, regardless of whether PFAS is landfilled (with adsorbents undergoing single use), or destroyed with ball milling or low-temperature incineration, life-cycle greenhouse gas emissions are approximately 0.2 kg CO₂e. Ongoing analysis is evaluating additional destruction techniques such as supercritical water oxidation, exploring different adsorbent performance, and investigating the dependence of type of treated water on life cycle assessment results.

Implications: Preliminary results indicate that treating PFAS rather than landfilling contaminated adsorbents saves large volumes of solid waste without an increase in greenhouse gas emissions. Every effort should be made to use adsorbents that can be regenerated while PFAS is destroyed to limit solid waste impacts of PFAS management.

Citations:

Argonne National Laboratory. Greenhouse gases, Regulated Emissions, and Energy use in Technologies (GREET) model, 2023 release. https://greet.anl.gov/

Ching, C., Klemes, M. J., Trang, B., Dichtel, W. R., Helbling, D. E. β-Cyclodextrin Polymers with Different Cross-Linkers and Ion-Exchange Resins Exhibit Variable Adsorption of Anionic, Zwitterionic, and Nonionic PFASs. Environ. Sci. Technol. 2020. 54: 12693-12702.