Joint aerobic biodegradation of synthetic and natural textile microfibers and laundry surfactants

Microfibers (MFs) represent one of the most prominent sources of microplastics in aquatic environments, primarily released during textile washing alongside surfactants found in laundry detergents. This study aimed to investigate the biodegradability of natural (cotton) and synthetic (polyester) MFs individually and in combination with two surfactants: sodium lauryl sulfate (SLS, anionic) and polyoxyethylene glycerol ester (PGE-OE6, nonionic). Using the OECD 301 F test, the research assessed biodegradation patterns and environmental interactions. Biodegradation profiles have been fitted to a pseudo first-order kinetic model and to a logistic kinetic model. Results showed that cotton MFs were partially biodegradable, achieving a 74.9% mineralization, while polyester MFs exhibited no biodegradability. Importantly, when combined with surfactants, the biodegradation of SLS was inhibited by polyester MFs, but cotton MFs enhanced SLS mineralization. Conversely, the combination of cotton MFs with PGE-OE₆ slowed the biodegradation of both the surfactant and the MFs, delaying the onset of cotton degradation. However, polyester MFs’ biodegradability remained unaffected by either surfactant. These findings emphasize the need for more comprehensive assessments of how MFs and surfactants interact in real-world environmental matrices, as these interactions can influence their persistence and ecological impact. The study highlights the scientific importance of understanding pollutant interactions to develop more effective environmental monitoring and mitigation strategies.