Volume: 3, 2024
3rd International PhD Student’s Conference at the University of Life Sciences in Lublin, Poland:
ENVIRONMENT – PLANT – ANIMAL – PRODUCT
Abstract number: E002
DOI: https://doi.org/10.24326/ICDSUPL3.E002
Published online: 24 April 2024
ICDSUPL, 3, E002 (2024)
Occurrence and dissipation mechanism of organic contaminants during sewage sludge anaerobic digestion. A critical review
Wiktoria Błaszczyk1*, Anna Siatecka1, Pavel Tlustoš2, Patryk Oleszczuk3
1 Department of Chemistry, Faculty of Food Science and Biotechnology, University of Life Sciences, Akademicka 15, 20-950 Lublin, Poland
2 Department of Agro-Environmental Chemistry and Plant Nutrition, Faculty of Agrobiology, Food and Natural Resources, Czech University of Life Sciences Prague, Kamycka 129, Praha 6 – Suchdol, 165 00, Czech Republic
3 Department of Radiochemistry and Environmental Chemistry, Institute of Chemical Sciences, Faculty of Chemistry, Maria Curie-Sklodowska University, Maria Curie-Sklodowska 3, 20-031 Lublin, Poland
* Corresponding author: wiktoria.blaszczyk@up.lublin.pl
Abstract
Sewage sludge contains contaminants of different types and is characterized by a large number of pathogenic vectors. As a result, it must undergo treatment or stabilization (such as, for example, anaerobic digestion (AD)) before environmental disposal. AD-derived products (solid digestate and liquid fraction) can be used as fertilizers and soil amendments. During this process, biogas is also produced, which is used for energy purposes. All these components can be contaminated with various compounds, whose percentage depends on the feedstocks used in the process (and their mutual proportions). This paper is a review of the studies dealing with the distribution of organic contaminants between the individual phases (solid digestate, liquid fraction, and biogas) during sewage sludge AD. Moreover, the mechanisms responsible for their dissipation are discussed and further research prospects regarding the removal of contaminants during sewage sludge AD are stressed. AD proves to be an effective method for removing some groups of contaminants from sewage sludge. Nonetheless, compounds such as benzotriazoles or per- and polyfluoroalkyl substances are degraded to a small extent during AD, creating a potential risk to humans and the environment. Contaminants are predominantly removed through biodegradation, but many compounds, especially those with hydrophobic properties, are also sorbed onto digestate particles. The process of sorption is suggested to reduce the bioavailability of contaminants. As a result of sorption, contaminants accumulate in the largest amount in the solid digestate, whereas in smaller amounts in the other AD products. Polar pharmaceuticals are particularly leached, while volatile methylsiloxanes and polycyclic aromatic hydrocarbons, characterized by a high Henry’s law constant, are volatilized into the biogas. The removal of compounds can be affected by AD operational parameters (sludge residence time, temperature), the type of sludge, physicochemical properties of contaminants, and sludge pretreatment used. The above-mentioned factors ultimately determine their final concentration, persistence, and sorption potential as well as the formation of metabolites.
Keywords: solid digestate, liquid fraction, biogas, biodegradation, mesophilic and thermophilic digestion
How to cite
W. Błaszczyk, A. Siatecka, P. Tlustoš, P. Oleszczuk, 2024. Occurrence and dissipation mechanism of organic contaminants during sewage sludge anaerobic digestion. A critical review. In: 3rd International PhD Student’s Conference at the University of Life Sciences in Lublin, Poland: Environment – Plant – Animal – Product. https://doi.org/10.24326/ICDSUPL3.E002