Changes in the pore structures of municipal solid waste samples with different abilities to provide support to the landfill structure during degradation: Analysis of synthetic waste using X-ray computed microtomography

The pore structure, which serves as a conduit for gas and leachate migration during municipal solid waste (MSW) landfilling, undergoes continuous changes in pore size and connectivity with waste degradation. In this study, we established two types of landfill simulation containers filled with either formless or fixed-shaped MSW particles. Computer tomography (CT) scanning technology was used to monitor the pore structures regularly in situ during degradation, and Avizo image processing software was used to extract the characteristic parameters of the pore structure. The results showed that the pore structures all had unimodal distributions. The pore structures of the formless synthetic MSW particles continued to shrink, the sizes of the nodal pores decreased, and the pore channels narrowed and shortened with degradation. In contrast, the pore structures of the fixed-shaped MSW particles continued to grow during degradation, the nodal pores enlarged, and the pore channels expanded. Specifically, the pore channel length increased by nearly 1000 μm. This finding indicated that changes in the pore structures of wastes could be determined by the supporting factors of waste particles and by the biodegradation of microorganisms. The pore structures grew when the supporting factors were predominant and shrank when microorganism biodegradation was predominant.