Exploring the Fate of Microplastics Disturbed by Earthworms Activities During Sewage Treatment by Vermifilter

Microplastics (MPs), an emerging contaminant with potential harm to the environment and human health, has received increasing attention recently. For targeting the influence of earthworm activities on migration and fate of MPs during the sewage treatment by vermifiltraion, this study explored and identified the types and strength of MPs in the vermifilter (VF) employing conventional biofilter (BF) as control by density separation, stereomicroscope inspection, and Microscope Fourier Transform Infrared Instrument analysis. Most importantly, the balance of MPs during the vermifiltration process was mapped to show the disturbing effects of earthworms. The results indicated that the VF could retain the MPs with 25.6 ± 6.5%, twice that of the BF. Fiber and transparent MPs were the most common types in the influent. The biofilm of the VF could harbor MPs approximately 4.28×104 particles per day, 2.91×104 particles higher than the BF biofilm. Furthermore, the MPs in earthworms body could be negligible due to lower abundance than that of the biofilms. Notably, filter depth is essential for affecting the distribution of microplastics in the VF (p < 0.05). Conclusively, the earthworms’ activities substantially altered the fate in the vermifiltraion compared with the BF. Further research into the mechanism of earthworm on MPs is considered necessarily