The recycling of bio-waste plays an important role in a circular economy as it transforms bio-waste into a valuable resource (organic fertilizer). However, even separately collected bio-waste can contain some plastic waste, which is usually separated after composting and not before it. Primary studies have confirmed the degradation of plastic during composting, but the release of microplastics from them has not been studied. This article presents a quantification and comparison of the release of microplastics from commonly used plastics during green waste composting. Microplastics were identified by Nile red staining and examination under a fluorescent microscope. Plastic degradation was assessed by weight loss calculation, scanning electron microscope (SEM), and Fourier-transform infrared spectroscopy (FTIR) analysis. On average, 17 to 52 microplastics’ are released from 5-by-5 cm pieces of conventional plastics during composting. The control polylactic acid sample showed the smallest amount of released microplastics: four particles on average. The number of released microplastics depended on the polymer type and thickness of the samples. The results of the current article can be further used for the prediction of microplastic generation and setting a limit on the plastic content in bio-waste
Almost a quarter of the plastic produced in Europe still ends up in landfills. In addition to the loss of valuable resources, this leads to the generation and accumulation of microplastics in landfills. The microplastics abundance in the refuse and their spatial distribution in the landfill body have not been practically studied. In the current work, changes in the abundance and characteristics of microplastics in landfill refuse from 3 age sections of the Lapės regional landfill, Lithuania, to a depth of 10–20 m were studied. A microplastics abundance of up to 55 particles/g or 52.8 g/kg was found. The lowest microplastics abundance was found in the old section, while the highest in the young (numerical) and the middle-aged (mass) sections. Moreover, microplastics abundance increased with the age of landfilled waste and depth, which may reflect the fragmentation of microplastics and their transport. Polyethylene and polypropylene were the dominant polymer types in all sections, while films were the dominant shape. The carbonyl index of PE microplastics was calculated to monitor microplastics oxidation. The analysis showed an increase of carbonyl index with landfill depth and landfill age, proving the intensive degradation of microplastics. Thus, landfills are large reservoirs of microplastics and their potential sources.