Do PFAS changes in landfill leachate treatment systems correlate with changes in physical chemical parameters?

[Display omitted] •Fifteen landfill facilities, with on-site treatment systems in Florida, were evaluated.•Changes between influent and effluent (Δ) were analyzed.•Δ conductivity, pH, alkalinity, and ammonia were associated with Δ PFAS.•Δ PFAS were associated with Δ Ba, Co, Ca, Fe, Mg and Zn.•Associations may be due to effects from dilution and chemical precipitation. Per- and polyfluoroalkyl substances (PFAS) have been found at relatively elevated concentrations in landfill leachates. Some landfill facilities treat physical-chemical parameters of their leachates using on-site leachate treatment systems before discharge. The objective of this study was to evaluate whether changes in physical-chemical parameters of leachate at on-site treatment systems (including bulk measurements, oxygen demanding components, and metals) were associated with concentration changes in PFAS. Leachates were evaluated at 15 on-site treatment facilities which included pond systems, aeration tanks, powdered activated carbon (PAC), sand filtration, reverse osmosis (RO) and combination treatment processes. Results show that most physical-chemical parameters and PFAS were significantly reduced in RO systems (over 90 %). For pond systems, statistically significant correlations (rs > 0.6, p 0.6, p