Commercial-scale remediation of per- and polyfluoroalkyl substances from a landfill leachate catchment using Surface-Active Foam Fractionation (SAFF®)

Abstract

This article presents the results from a commercial-scale field trial of the Surface-Active Foam Fractionation (SAFF) process for the removal of per- and polyfluoroalkyl substances (PFAS) from a landfill leachate catchment at the Telge Recycling plant, Sweden. There have been 23 sampling events for PFAS influent and effluent concentrations over the course of 10 months, during which approximately 80,000 m3 of leachate feed has been successfully treated without the need for complex pretreatment. The contracted throughput was 330 m3 per day (120,000 m3/year), but, in practice, it varied between 200 m3 and 500 m3 per day depending upon the inventory of the upstream leachate catchment. Over the trial period, it was demonstrated that SAFF was successful in removing ≥98.7% perfluorooctane sulfonate (PFOS), ≥99.7% perfluorooctanoic acid (PFOA), and ≥98.8% perfluorohexane sulfonate (PFHxS) from the feed stream without using absorbent media or chemical amendment consumables, including the partial/significant removal of other PFAS species. The reported removal percentages are constrained by the limit of reporting (LOR) of analytical testing of the “treated stream”; the actual removal percentages could be higher as detailed by a single sampling event “I” included herein. The mean concentrations of the treated stream were ≤2.34 ng/L PFOS, ≤1.28 ng/L PFOA, and ≤1.00 ng/L PFHxS; the contractual criteria requirement was to reduce PFOS to <50 ng/L. The results are concordant with those obtained by Burns et al. (2021) who demonstrated that SAFF technology removed ≥99.8% PFOS, ≥99.8% PFOA, and ≥98.4% PFHxS from a PFAS-contaminated groundwater stream at the Army Aviation Centre Oakey military base in Australia. The present study extends what was learned from the previous Australian groundwater study in that there is more complex chemistry associated with the leachate feed stream arising from landfill receipt of domestic, commercial, and industrial waste to the landfill cells. In addition, the climatic dependency that was considered by Burns et al. (2021) is explored in a colder environment and is found to be practically insignificant with respect to PFAS removal. Burns et al. (2021) asserted that nearly complete PFAS removal is achieved if the Brusseau adsorption coefficient is greater than approximately 1 µm. The present study extends this analysis to demonstrate that removal percentages fall to approximately 0 at an adsorption coefficient of 0.02 µm with a functional form of a sigmoid on semi-log axes. A full set of third-party laboratory test certificates are provided in the Supporting Information.