Physicochemical characterization and heavy metals leaching potential of municipal solid waste incinerated bottom ash (MSWI-BA) when utilized in road construction.

In this study, the physicochemical properties, microstructure, and heavy metal leaching potential of various municipal solid waste incinerated-bottom ash (MSWI-BA) particle sizes were detected. The environmental risks that possibly result from the utilization of MSWI-BA aggregate in road construction are discussed. The air-dried MSWI-BA was sieved into four groups, including 4.75-9.5 mm, 2.36-4.75 mm, 0.075-2.36 mm, and < 0.075 mm. X-ray fluorescence (XRF), X-ray diffraction (XRD), and scanning electron microscopy (SEM) analyses were conducted. It was found that the main elements of MSWI-BA are Ca, Si, and Al; the major heavy metals are Zn, Cu, Cr, and Pb, and the main mineral compositions are quartz and calcite. Even though the major elements were found to be related to MSWI-BA particle size, the micropores, attached particles, and hydration products were shown to be independent on the particle size. The standard leaching test and a simulated leaching experiment with four solid/liquid ratios were implemented to study the leaching behavior of Zn, Cu, Pb, and Cr. Results showed that the leaching characteristics of selected metals were affected by the species of metal, MSWI-BA particle size, solid/liquid ratio, and the test method. The MSWI-BA aggregate was found to be an appropriate substitute material for natural aggregate in road construction due to its low metal leaching potential.