A comprehensive study on quantification and characterization of microplastics in compost, landfill-soil and leachate

Microplastics (MPs), a category of synthetic emerging pollutants, have been detected in various environmental matrices. This study assesses the abundance of MPs in the soil, wet compost (WC), Black soldier compost (BSC) and landfill leachate (LL) of the municipal solid waste management plant. Samples were pretreated with a Fenton reagent, followed by density separation and analysed using a digital portable microscope. They were then categorized based on their shape, colour and size to provide information on their distribution. The work reveals an average MP count of 7590 ± 1004.092 MP kg^-1 in soil. MPs were 5900 ± 565.69 MP kg^-1 for BSC, 11,350 ± 353.55 MP kg^-1 for WC and LL samples 98.83 ± 6.83 MP L^-1. Notably, a significant proportion of MPs, 85% in soil, 86% in compost and 72.6% in LL, measured size less than 300 µm. Samples showed different proportions of fragments, microbeads and fibres, with white/transparent and black being the predominant colours of MPs. Additionally, the study identifies the physicochemical properties of the samples, and the polymer types are identified using attenuated total reflectance-Fourier transform infrared spectroscopy. The study revealed that polypropylene and polyethylene are the most abundant polymers in the samples, indicating that landfills serve as significant sources of MPs. The adopted MP extraction method was tested for its recovery efficiency, and the recovery rates for leachate, compost and soil were found to be 94.3%, 80% and 77.9%, respectively. This research offers insight into the types and abundance of MPs in southern India's landfills, prompting further studies on detection methods.