Volume: 5, 2026
5th International PhD Students’ Conference at the University of Life Sciences in Lublin, Poland:
ENVIRONMENT – PLANT – ANIMAL – PRODUCT
Abstract number: E004
DOI: https://doi.org/10.24326/ICDSUPL5.E004
Published online: 22 April 2026
Differential effects of protic ionic liquids on the speciation of potentially toxic elements in digested sewage sludges and the ecotoxicity of treated residues
Wiktoria Błaszczyk*1, Karolina Fila1, Paweł Muszyński1, Tadeusz Paszko1, Monika Raczkiewicz2, Patryk Oleszczuk2 and Anna Siatecka1
1 Department of Chemistry, Faculty of Food Science and Biotechnology, University of Life Sciences, 15 Akademicka St., 20-950 Lublin, Poland
2 Department of Radiochemistry and Environmental Chemistry, Institute of Chemical Sciences, Faculty of Chemistry, Maria Curie-Sklodowska University, 3 Maria Curie-Sklodowska Sq., 20-031 Lublin, Poland
* Corresponding author: wiktoria.blaszczyk@up.edu.pl
The continuously increasing amount of digested sewage sludges (SSLs) requires effective and safe treatment methods due to the presence of hazardous substances, including potentially toxic elements (PTEs). The aim of this study was to apply protic ionic liquids (PILs) for PTEs removal from SSLs, evaluating both removal efficiency and changes in PTE speciation in post-treatment residues. 1-methylimidazolium chloride ([H1Cim]Cl) and triethylammonium hydrogen sulfate ([TEA][HSO4]) were used to extract Zn, Cu and Pb from SSLs with different chemical characteristics. PTE speciation was determined using the Tessier sequential extraction method. The toxicity of SSLs (before and after PTE removal) toward plants (Lepidium sativum) and soil invertebrates (Folsomia candida) was also assessed.
[H1Cim]Cl showed higher extraction efficiency for PTEs than [TEA][HSO4], particularly for Zn and Cu. [H1Cim]Cl effectively removed PTEs associated with fractions F1–F4, especially those bound to organic matter, reducing the total ΣF1–F5 of most PTEs. Partial redistribution of released PTEs into the residual fraction (F5) was observed, indicating their secondary binding to the mineral phase. The extraction efficiency depended on SSL type and initial PTE speciation. Treatment with [TEA][HSO4] led to the formation of poorly soluble sulfate(VI) compounds (especially Zn and Pb), which remained in SSLs and accumulated mainly in fraction F1. The ecotoxicity of SSLs depended on the PIL, the SSL type, and test organism. At sludge doses recommended for agricultural applications (0.1–0.2%), [H1Cim]Cl-treated SSLs did not exhibit significant toxicity toward L. sativum. However, higher doses (0.3–1.5%) increased toxicity due to the accumulation of residual [H1Cim]+ cations in the treated SSLs. SSLs treated with [TEA][HSO4] showed no phytotoxicity across the entire dose range but were toxic to F. candida from a dose of 0.2%, likely due to Zn and Pb sulfate(VI).
The results indicate that properly selected PILs can reduce PTEs content and alter their speciation, thereby limiting bioavailability. This approach shows potential for SSL valorization in soil remediation and fertilization, while supporting resource recovery and circular economy principles.
This research was funded in whole by National Science Centre, Poland under Grant number 2021/43/D/NZ9/02718.
Keywords: ecological risk; mobility factor; sequential extraction; Tessier method; toxicity
How to cite
Błaszczykm W., Fila K., Muszyński P., Paszko T., Raczkiewicz M, Oleszczuk P., Siatecka A., 2026. Differential effects of protic ionic liquids on the speciation of potentially toxic elements in digested sewage sludges and the ecotoxicity of treated residues. In: 5th International PhD Students’ Conference at the University of Life Sciences in Lublin, Poland: Environment – Plant – Animal – Product. https://doi.org/10.24326/ICDSUPL5.E004