## 5 Discussion  
The results of the chemical-physical and geotechnical analyses of the contaminated soil samples, along with the characterization of green materials and pelletization tests, provide valuable insights into the potential for soil remediation and the use of industrial by-products as sustainable alternatives in the production of stabilized soils. The geotechnical analyses revealed that the variability in the physical properties of the soils--such as compaction and moisture content--plays a crucial role in determining their suitability for practical applications. Samples with higher moisture content, such as Soil 5, tend to be more compact and stable, while those with lower moisture content, \begin{table}
\begin{tabular}{c c c c c} \hline
**Parameter** & **Units** & **Tested Values** & **Optimal Value** & **Results** \\ \hline Rotation speed & rpm & 15–45 & 45 & Best granule quality and consistency \\ Inclination angle & degrees & 30–45 & 45 & Best granule cohesion and pellet formation \\ Moisture content & \% & 5–15 & 10 & Best cohesion during granulation \\ Granulation time & min & 10–20 & 15 & Best pellet formation and granule consistency \\ \hline \end{tabular}
\end{table} 
Table 10: Characteristics of pelletization process. like Soil 3, are more permeable. These findings suggest that, before using contaminated soils in the stabilization process, a pretreatment phase to regulate moisture content and improve material cohesion would be beneficial, ensuring the quality and stability of the final product. The interaction between the soil's physical structure and the presence of contaminants could significantly affect the treatment's effectiveness, thus requiring careful management of process variables like moisture and soil compaction. Leaching tests, which identified contamination primarily from heavy metals (As, Cr, and Cd), are particularly relevant, suggesting that while the stabilization process may reduce the accessibility of these contaminants, long-term stability must still be monitored. The pH-dependent, percolation, and dynamic leaching tests demonstrated how contaminant mobilization varies under different environmental conditions. Therefore, it is crucial to design the stabilization process with consideration for the materials' ability to bind contaminants and prevent their release into the environment. Further analysis of the contaminants' behavior over the product's lifecycle could provide valuable insights for safer and more sustainable applications. The characterization of green materials highlighted the potential of several industrial by-products, such as municipal solid waste fly ash, ground granulated blast furnace slag, and marble sludge, all of which, despite their differing chemical compositions, share characteristics that make them suitable for the stabilization of contaminated soils. The significant presence of calcium in many of these materials suggests that they could improve the mechanical properties and chemical stability of the resulting pellets. However, the variability in composition--such as the difference in chloride content between MSWI-FA and W-FA--emphasizes the importance of preliminary treatments, like washing, to reduce corrosion risks and enhance environmental stability. Washing appears to be a crucial step in lowering chloride and sulfate content, which would otherwise compromise the durability of the final product. The XRD analysis results, showing the presence of crystalline phases such as calcite and portlandite, support the possibility of improving the rheological properties and thermal stability of the finished products. Among other advantages, as also highlighted in previous work [32], the presence of GGBFS reduces pore volume and has been recognized increases the immobilization ratio of heavy metals. Additionally, MS for improving the cohesion of the treated material and reducing the risks of contaminant dispersion.