Abstract
Many consumer and industrial products containing per- and polyfluoroalkyl substances (PFAS) are disposed of in landfills at the end of their usage. These PFAS were detected at high levels in landfill leachates and these leachates are ultimately discharged into an adjacent natural water body or to a wastewater treatment plant (WWTP). Therefore, it is important to track the fate of PFAS within landfill environments.
The overall goal of this dissertation is to assess PFAS in landfill environments, which can be used to establish policies that will minimize the cycling of PFAS in the environment including the possible requirements for treating PFAS in landfill leachates. In order to achieve this overall goal, three focused studies were conducted with the following objectives: a) Identify the change of PFAS concentrations for 15 on-site leachate treatment systems through experimental measurements; b) Identify PFAS concentrations in aqueous components for 39 landfills through experimental measurements and identify their relationships with landfill characteristics by correlation analysis; c) Identify PFAS mass fluxes in different aqueous components within two selected landfill environments based on mass balance analysis, and identify the fraction of PFAS released from the solid waste.
The results of the first study suggested that reverse osmosis (RO) is the only evaluated system that showed considerable decrease of PFAS concentrations (98% to 99%) in the permeate. The results of the second study suggested that PFAS concentrations in groundwater and stormwater are lower than that in gas condensate and landfill leachate, and PFAS concentration in leachate is also impacted by the operational status of landfills (active or not) and short-term rainfall. The results of the third study suggested that the mass flux of PFAS released from disposed solid waste was around 36.8 g/ha-yr, which was approximately 1% to 3% of total amount of PFAS within the solid waste. Results also show that a major portion of PFAS (95% to 97%) released from solid waste flows into landfill leachate.