Pilot-Scale Continuous Foam Fractionation for the Removal of Per- and Polyfluoroalkyl Substances (PFAS) from Landfill Leachate

Abstract

Per- and polyfluoroalkyl substances (PFAS) are of concern for their ubiquity in the environment combined with their persistent, bioaccumulative, and toxic properties. Landfill leachate is often contaminated with these chemicals, and therefore, the development of cost-efficient water treatment technologies is urgently needed. The present study investigated the applicability of a pilot-scale foam fractionation setup for the removal of PFAS from natural landfill leachate in a novel continuous operating mode. A benchmark batch test was also performed to compare treatment efficiency. The ΣPFAS removal efficiency plateaued around 60% and was shown to decrease for the investigated process variables air flow rate ( Q air ), collected foam fraction (% foam ) and contact time in the column ( t c ). For individual long-chain PFAS, removal efficiencies above 90% were obtained, whereas the removal for certain short-chain PFAS was low (<30%). Differences in treatment efficiency between enriching mode versus stripping mode as well as between continuous versus batch mode were negligible. Taken together, these findings suggest that continuous foam fractionation is a highly applicable treatment technology for PFAS contaminated water. Coupling the proposed cost- and energy-efficient foam fractionation pretreatment to an energy-intensive degradative technology for the concentrated foam establishes a promising strategy for on-site PFAS remediation.

Impact of Salinity and Temperature on Removal of PFAS Species from Water by Aeration in the Absence of Additional Surfactants: A Novel Application of Green Chemistry Using Adsorptive Bubble Fractionation

“…More recently, Burns et al provided information of the first full-scale treatment of an active landfill leachate catchment, a demonstration of foam fractionation efficiency where both PFAS species and non-PFAS amphiphilic substances are present in the feedwater. Their results indicate similar levels of removal for individual PFAS compounds when compared to the investigations reported by Robey et al and Smith et al with overall total PFAS removal highly dependent on the mix of short and long-chain PFAS in the feed.…”

“…Robey et al 24 obtained a median PFAS removal of 92%, with the process found to be ineffective at removal of the smallest and largest PFAS molecules. Smith et al 25 had a lower overall removal rate (∼60%), with the removal process constrained by the high percentage of short-chain PFAS (∼46% of the total PFAS content) in the leachate water, as these were only marginally removed. Neither study applied any additional surfactant to enhance PFAS removal.…”

EPA's detection methods, the drinking water treatability database, and innovative technologies for PFAS remediation

“…While approximately an average of 60% of total PFAS were removed using continuous foam fractionation, this study by S. J. Smith et al (2022b) demonstrated that it mattered if the influent (the PFAS-contaminated water) was introduced into the foam fractionation system from below the foam layer or from above the foam layer. Significantly more long-chain perfluoroalkyl carboxylates (PFCA) and perfluoroalkyl sulfonates (PFSA) were in the foam when the influent was added from above the foam layer than from below this layer.…”

“…Some of the innovative technologies for the remediation of PFAs have, in general, moved away from the use of activated carbon and resins in the EPA's drinking water TDB that have disposal challenges and the need to be replaced after they are saturated with PFAS, as discussed earlier in this article. These innovations, listed in Table 4, apply heat, surfactants, gas, biochar, and also the physical milling process to remove PFAS from water and compared to the EPA's drinking water TDB's technologies, they do not face disposal T A B L E 4 Some of the innovative technologies for the treatment of PFAS in water (Amusat et al, 2021;Berg et al, 2021;Cagnetta et al, 2016;S. J. Smith et al, 2022b;Zhao et al, 2009;Zozulya & Pletneva, 2015) et al, 2022).…”

Electrochemical Oxidation for Treatment of PFAS in Contaminated Water and Fractionated Foam─A Pilot-Scale Study

“…The influent, effluent, and collapsed foam samples ( n = 4 for each) from the FF were analyzed without analytical duplicates. The analytical methods for both the water samples and quartz microfiber filters are described in Supporting Information Sections 3 and 4 and have also been described in detail previously. , The influent and effluent samples of all electrochemical and FF tests were also analyzed with TOP assays, which aim to oxidize unknown PFAA precursors to PFCA to enable concentration measurements with targeted analysis. The TOP assay method is described in Supporting Information Section 5 and has been previously described by Houtz and Sedlak (2012) …”