Thomas Hartnik
Director
Biography
Education:
Doctoral degree (Dr.scient) in ecotoxicology from the Norwegian University of the Environment and Biosciences in 2008
Areas of expertise:
- management experience
- varied professional background from academia, state administration and private business within circular economy and pollution and climate-related issues.
- Project manager for larger R&D and consulting projects.
- Experience from boards of the Research Council of Norway and professional networks
Authors
Karen Ane Frøyland Skjennum Jan Mulder Gijsbert Dirk Breedveld Thomas Hartnik Nicolas Estoppey Erlend Grenager SørmoAbstract
The present study investigates the long-term immobilization efficiency of biochar on target per- and polyfluoroalkyl substances (PFAS) and precursors in well-drained soils contaminated by aqueous film-forming foam (AFFF) (Ʃ27PFAS = 1624 ± 276 µg/kg) over 2 years. The total oxidizable precursor (TOP) assay revealed a large precursor reservoir in the soil. Fifteen outdoor field-scale columns were packed with contaminated soil (48 kg) without (control columns, triplicates) and with biochar amendments: Three sewage sludge-based biochars were homogeneously mixed into the soil at a 1% (w/w) dose in triplicate columns. One of the biochars was additionally applied as a barrier at the column base (1% w/w) in a separate set of columns. The best-performing biochar immobilized long-chain PFAS by 91.0 ± 35.0% and short-chain PFAS by 96.7 ± 32.9%, possibly due to a well-developed porosity. Compared to the control columns, the fluctuating PFAS leaching were negligible in columns amended with the best-performing biochar, but the immobilization efficiency of short-chain PFAS decreased after one year (from 97.8% to 74.2%). Applying biochar as a barrier was two times more effective than homogenous mixing, and the effect was most pronounced for long-chain PFAS. Our findings suggest that biochar may immobilize precursors, notably CF3-CF5 precursors, to the same extent or better than their typical target perfluoroalkyl acids transformation products. More research is, however, needed to confirm these trends. Going beyond simple lab experiments, this study suggests that biochar is a promising solution for PFAS remediation and brings the technology closer to field application.
Authors
Karen Ane Frøyland Skjennum Thomas Hartnik Gijs D. Breedveld Erlend Grenager Sørmo Jan MulderAbstract
Per- and polyfluoroalkyl substances (PFAS) pose significant environmental and human hazards due to their resistance towards natural degradation. Anthropogenic activities have resulted in worldwide spreading of PFAS, and soil remediation of PFAS is challenging due to its persistent and mobile nature. Amendment with commercial activated carbon (AC) of fossil origin is one of the preferred immobilization strategies for contaminated soil. However, waste-based sorbents may represent a greener alternative to AC. Here, we review the status and potential for the use of waste-based materials as PFAS sorbents in soil remediation. Key properties in the search of candidate materials are discussed, followed by an overview of potential sorbents. The materials reviewed are bark, protein-rich waste, chitosan, amine-modified waste, compost, biosolids, biochar produced from waste-based substrates, and a selection of industrial waste, notably bottom- and fly ash, char and slag. Performance and sorption behavior of these materials are compared for long- and short-chain PFAS, and their applicability is further discussed. Besides great sorption capacity and affinity, promising amendments combine high abundance, low cost, a potential for modification and low risk. Biochar emerges as the most mature and promising candidate of the materials reviewed. Other waste-based materials also show great PFAS sorption capacities, but their performances in soil have not been properly assessed. Besides sorption studies in environmentally relevant matrices, upscaling and long-term studies are needed to further examine the potential use of waste-based sorbents in remediation of PFAS contaminated soil.
Abstract
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