The leaching potential of sewage sludge and municipal waste incineration ashes in terms of landfill safety and potential reuse

Incinerations residues from different types of materials (sewage sludge incineration ash and municipal waste incineration ashes) can either be by-products used in industry, or can pose a serious environmental problem related to their composition and the presence of potentially hazardous elements. State regulations and standards indicate whether material is inert, non-hazardous or hazardous. These standards, however, do not provide a complete overview on the leaching behavior of potentially hazardous elements in the environment. This study presents the result of batch experiment performed in accordance with the PN-EN 12457-2 (2006) and PN-EN 12457-4 (2006) standards. The results indicated that the leachability of elements is strongly dependent on the mineral composition of the waste product (the concentration and composition of soluble phase), the chemical composition (the mobility of hazardous elements and their affinity to soluble minerals), and the pH. To ensure environmental safety a thorough characterization of the waste is required followed by qualitative assignment to a particular waste type based on available guidance. Furthermore, to avoid leaching of potentially harmful elements into soils or surface water, it is also paramount to perform environmental impact assessment of wastes used as by-product in industry e.g., as building or road construction materials (aggregate) and fertilizers.