Stevanoni, J. | CRC Care International Cleanup Conference, 8-12 September, Adelaide, Australia, 20 slides, 2019

Sandy clay (A soil) and clay (B soil) soils collected and spiked with AFFF 3M Light Water™ were amended using brown wastes, nutrients, and soil ameliorants to facilitate fungal growth and incubated in 1.5-L Pyrex bioreactors for 41 days. The soil ameliorants comprised equal weights of straw, woodchips and poultry manure and were mixed into the soils at ~40% wet weight to provide a low pH, high oxygen environment to grow fungi. Two bioreactors containing A soil were spiked with a starting concentration of ~106 mg/kg PFOS+PFHxS, and two bioreactors containing B soil were spiked with ~8 mg/kg. All the containers had water-saturated air pumped through the mixture to limit drying and provide oxygen. Samples were collected on days 0, 7, 12, 21, 27, 34, 41 and analyzed for 10 PFAS compounds. White rot fungal hyphae were observed at various times throughout the experiment but were more abundant in A soil. All soils showed an initial PFAS increase, attributed to bacterial precursor transformation. Overall, PFAS in A soils decreased 18-57%. PFOA and PFOS decreased by 53% and 57%, respectively. Trends in B soils increased throughout the 41 days for 7 compounds. From day 12-27, PFHpS, PFHxS, and PFOS decreased by 9%-18%. PFOA decreased by 17%. Differences between the two soils are attributed to differences in oxygen and sorption of enzymes onto the soils and in PFAS concentrations. Soil B did not allow sufficient oxygen for strong fungal activity, allowing bacteria to become dominant. Further research should examine PFAS bioremediation in various soil types, examining both enzyme sorption to soil and the sorption of PFAS to various soil types. http://adelaide2019.cleanupconference.com/wp-content/uploads/2019/09/M32b.pdf