A state-of-the-art review of solid waste leaching mechanisms and evaluation methodologies

Recovery and recycling are essential strategies in solid waste management, but the potential leaching of harmful substances poses significant environmental concerns. This review examines the framework, methodologies, and mechanisms of leaching tests, focusing on mass transport (e.g., diffusion, convection) and thermodynamic restrictions (e.g., solubility, adsorption-precipitation) that influence contaminant release. The classification of leaching tests into batch, column, and pH-dependent methods highlights the need for selecting appropriate protocols based on waste properties, with batch tests for short-term assessments, column tests for long-term behaviour, and pH-dependent tests for simulating varied environmental scenarios. Future leaching studies should incorporate climate change variables, such as rainfall patterns and temperature fluctuations, to enhance the predictive reliability of contaminant mobility. Standardizing leaching protocols across regions is critical to ensuring consistent results, supporting sustainable waste management strategies globally.