Microplastic release and sulfate reduction response in the early stage of a simulated landfill.

[Display omitted] • Landfill has extremely strong MPs release capacity in the early stage. • The sedimentary phase of leachate is the main sink of MPs. • Leachate circulation accelerates MPs release and fragmentation. • Sulfate reduction process promotes the release of MPs. • MPs release behavior can be attenuated in advance by leachate circulation. Landfills are essential facilities for treating and disposing municipal solid waste. They emit sulfur-containing odors and serve as an important sink for a new type of pollutant called microplastics (MPs). This study focused on the initial stage of anaerobic degradation to establish the relationship between the release of MPs and odor generation. Our findings show the rapid release of MPs into the leachate in the early stage of landfill and their predominant accumulation in the leachate sediment. The circulating leachate contained 1.45 times higher concentrations of MPs than the noncirculating leachate, with a peak concentration of 39 items·L−1. In addition, fragmentation of MPs occurred. The percentage of MPs with particle sizes of 2.5–5 mm decreased from 66.70 % to 22.32 %, while those measuring 0.1–0.5 mm increased by 33.12 %. A positive correlation was observed between MP release and sulfate reduction. Although leachate circulation increased the release of MPs, it also reduced the overall release time and total amount of MPs exported from the landfill. Compared with the initial landfill waste, the leachate operation mode, regardless of circulation, resulted in a 6.15–8.93-fold increase in MP release. These findings provide a valuable foundation for the simultaneous regulation of traditional pollutant odor and new pollutants (MPs) in landfills. [ABSTRACT FROM AUTHOR]