| dc.description.abstract | Per- and polyfluoroalkyl substances (PFAS), commonly referred to as "Forever chemicals," are characterized by their enduring persistence and wide distribution due to their chemical properties and extensive usage. Elevated levels of certain PFAS compounds have been associated with raised cholesterol, altered liver enzymes, decreased infant birth weights, compromised vaccine response in children, elevated risk of high blood pressure/pre-eclampsia in pregnant women, and increased likelihood of kidney/testicular cancer. Contaminated soil serves as a long-term source for PFAS, allowing these compounds to leach into groundwater and the surrounding ecosystem. Aqueous film-forming foams (AFFF) used at firefighting training sites is a significant source of PFAS contamination, as the compounds migrate into the soil, contaminating groundwater and potentially affecting the broader environment.
This study aims to remediate PFAS-contaminated soil from the firefighting training facility at Oslo airport by evaluating the efficacy of waste timber (TW and CWC) and wastewater treatment sludge biochar (DSL, USL, and MS) at concentrations of 1% and 4% in reducing PFAS levels. The specific PFAS compounds being targeted are 6:2 FTS, PFNA, PFOS, PFBS, and PFHxS. The investigation involves the use of up-flow percolation columns with flow circulation to assess the efficiency in reducing PFAS leaching and to validate derived Kd values with typical batch test data.
The results highlight the significant influence of biochar material choice on the sorption behavior of PFAS compounds. Wastewater treatment sludge-derived biochar (DSL, USL, and MS) showed superior performance in sorbing and reducing PFAS concentrations in water compared to waste timber-derived biochar (TW and CWC). PFAS compounds with longer fluorinated carbon chains exhibited greater sorption potential, as indicated by higher Log Kd values. The findings suggest that sorption observed in the up-flow percolation column test at equilibrium has lower Kd values than expected in batch systems, attributed to limited accessibility of soil surfaces. This approach provides a more realistic means of determining sorption parameters.
In conclusion, these results indicate that the selection of biochar material plays a crucial role in the sorption characteristics of PFAS compounds. The biochar derived from sludge demonstrates higher effectiveness in sorbing PFAS compounds and reducing their concentrations in water during up-flow percolation column with flow circulation. This underscores the potential of sludge-based biochar as a promising remediation option for PFAS-contaminated environments. | |