Leachate recirculation to reduce PFAS discharge from landfills.

Area of Science:

• Environmental Science
• Environmental Chemistry
• Waste Management

Background:

• Persistent challenge of per- and polyfluoroalkyl substances (PFAS) removal from complex landfill leachate.
• Need for innovative strategies to enhance PFAS retention within landfill environments.

Purpose of the Study:

• Investigate leachate recirculation as a method to increase PFAS retention in landfill materials.
• Evaluate the effectiveness of leachate recirculation for PFAS reduction in landfill leachate.

Main Methods:

• Lab-scale column reactor experiments simulating landfill conditions.
• Analysis of eleven PFAS compounds (nine carboxylates, two sulfonates) at varying concentrations.
• Monitoring PFAS concentrations in leachate, landfill organics, and plastics over twelve recirculation cycles.

Main Results:

• Leachate recirculation significantly enhanced PFAS sorption onto landfill organics and plastics.
• PFAS concentrations increased dramatically in landfill organics (134-1000x) and plastics (37-329x) after twelve recirculations.
• Higher PFAS removal efficiency observed with increased carbon chain length and Log K_oc values.
• Complete removal of PFAS with eight or more carbons (except PFOA) from leachate after six and twelve recirculations.
• Short-chain PFAS (C≤7) showed 20-65% retention after twelve recirculations.
• No significant PFAS desorption observed from landfill materials.

Conclusions:

• Leachate recirculation is a viable strategy for effective PFAS removal from landfill leachate.
• This approach facilitates high concentrations of PFAS retention within landfill organics and plastics.
• Further large-scale studies in real-world landfills are necessary to confirm performance and feasibility.