MSW Incinerated Ashes from Delhi: Study of Leaching Characteristics for Disposal and Reuse Options

Municipal solid waste (MSW) incineration (MSWI) in waste-to-energy (WtE) facilities generates about 20–25% residues as bottom ash (85%) and fly ash (15%). This study aims to determine the leaching behavior of these residues collected from two MSWI plants in Delhi to ascertain whether they are suitable for reuse in geotechnical applications or must be disposed in landfills. EN 12457-2/4 (2002) batch leaching tests were performed on bottom ash (BA), fly ash (FA), and combined ash (85% bottom ash and 15% fly ash). The leaching characteristics were compared to international regulatory standards for disposal toeur% landfills and reuse in field applications. It was revealed that bottom ash and combined ash were acceptable for disposal to non-hazardous waste landfills, whereas fly ash can only be disposed in hazardous waste landfills due to excessive leaching of total dissolved solids (TDS), Cl− and \({\text{SO}}_{4}^{ - 2}\) from FA. BA was found acceptable for reuse in field applications in a restricted manner, whereas the issue of excess sulfates and chlorides needs to be addressed before unrestricted reuse. Mixing of BA and FA result in transfer of contaminants from highly contaminated FA to less contaminated bottom ash and thereby necessitate intensive treatment of CA prior to reuse in field applications. Hence, co-disposal of BA and FA is should be avoided.