Environ Sci Pollut Res Int. 2022 Jan 21. doi: 10.1007/s11356-022-18696-z. Online ahead of print.
ABSTRACT
Municipal solid waste (MSW) is a highly heterogeneous porous medium that contains a variety of components and has complex pores and solid structures. Macroscale experiments are insufficient to describe the hydraulic and mechanical properties of MSW, especially for preferential flow in pores and the reinforcing effect of solids. For a deep understanding of the microscale structure of MSW, CT scanning tests were carried out on two kinds of samples prepared in the laboratory and drilled in landfills. MSW images were divided into pores and solids through dynamic threshold segmentation and morphological denoising methods. The distributions of pore size and structural solid angle were calculated by the maximum inscribed sphere (MIS) algorithm and angle statistical algorithm based on the surface model, respectively. According to the pore-size distribution, the pores were divided into large (diameter > 1 mm), medium (1 mm > diameter > 0.1 mm), and small (diameter < 0.1 mm) pores in MSW. Under a vertical stress of 50 kPa, the porosities of the large, medium, and small pores were 35%, 12%, and 26%, respectively. As the vertical stress increased to 400 kPa, the porosity of large pores decreased significantly to 15%, while the porosities of medium and small pores remained almost unchanged. In addition, the structural solid angle tended to be horizontal under compression, but its influence was limited. The structural solid angle was mainly concentrated at approximately 30-32°. The probability distribution of the structural solid angle could be well fitted using the Gauss function.
PMID:35064512 | DOI:10.1007/s11356-022-18696-z
