Analysis of heavy metals in Incineration Bottom Ash in Singapore and potential impact of pre-sorting on ash quality

Semakau Landfill, Singapore's only waste landfill, is estimated to be filled completely by 2035. To avert future crisis for a new landfill, it is crucial to divert the incineration ash and utilize it for construction purposes. Understanding characteristics of incineration ash would be the first step towards ash utilization. This paper analyses the chemical and physical characteristics of the bottom ash from a Singapore Incineration Plant via Toxicity Characteristic Leaching Procedure (TCLP) and Scanning Electron Microscope (SEM). These characteristics are used to identify and relate the ash components- heavy metals and unburnt waste, to their responsible sources in the various waste streams in Singapore. This paper also reviews waste streams that should be targeted for pre-sorting of municipal solid waste to improve the ash quality and complement any post-treatment processes for the ash.