Sewage sludge spreading on arable land – PFAS in sludge, soil, crop and earthworm
Is the use of municipal sewage sludge on arable land a spreading route for PFAS?
Per- and polyfluoroalkyl substances (PFAS) are used in products and industrial processes and have been shown to be long-lasting with negative effects on the environment and health. There are more than 5,000 different PFASs in circulation and about 20 of them are usually monitored in sludge from municipal wastewater treatment plants (WWTPs). Previous studies have shown that known PFASs make up 11-15% of the extractable organic fluorine (EOF) in sludge.
The project Sludge spreading on arable land has been ongoing since 1981 and is carried out on two experimental areas outside Malmö and Lund, respectively: Petersburg with light clay (14% clay) and Igelösa with medium clay (26% clay). The purpose of the experiments in Skåne is to investigate the effects on soil and crops when sewage sludge is spread on arable land.
The aim of this project is to carry out an extended characterisation of PFAS including EOF in applied sludge, soil, earthworm and crop and to compare the concentrations with samples from a reference site.
The study also aims to provide insight into both known and unknown PFASs in sludge-improved soil, accumulation in crops and worms, and to assess whether precursors in sludge constitute a long-term emission reservoir of more mobile PFASs.
The project has been granted funding from Svenskt Vatten Utveckling (project number 21-107), but Ragn-Sells and Revaq also contribute funding.
Samples for analysis of PFAS will be taken on sludge from the Sjölunda WWTP in Malmö, which is spread in the field trial in Petersburg. Extraction and analysis with methodology developed at Örebro University for targeted analysis of a sample of PFAS, and EOF (Kärrman et al. 2017, Yeung et al. 2017). Sampling will mainly take place during the autumn of 2021 and the autumn of 2022.