Review of MSWI bottom ash utilization from perspectives of collective characterization, treatment and existing application

Municipal solid waste incineration (MSWI) bottom ash has gained increasing attentions for its friendly application worldwide, due to promotion of waste recycling. One of the biggest concerns for incineration bottom ash (IBA) utilization lies in its elevated metal concentrations and leaching potential. While challenges faced by the user are miscellaneous based on several aspects-regulations and rules, the heterogeneity of IBA sources, specific risks arisen from individual applications and/or mixed public views, etc. Extensive knowledge on IBA characterization, existing treatment and application contributes to optimize life cycle of the bottom ash, herein enhancing the IBA management practices. On the understanding that both feedstock and the process for incineration are various, properties, treatments and applications of the IBA are accordingly different. Nevertheless, literature reviewed data indicate evidently that IBA, varying in its original resources and treatment facilities though, shares common geotechnical and chemical properties. As the technology development on the IBA is dominated by these common properties, through which the proper treatment and application could be well determined. In this review three perspectives were concentrated. First, general properties of IBA e.g. heavy metals and their leaching potential, bulk components, particle size distribution and pH were investigated, whereby the general trends were indicated with collective plots. Secondly, the existing status quo on IBA treatment methods and applications were investigated, suggesting a highest potential as low-strength aggregates. Thirdly, toxicity studies and LCA on IBA as emerging research topics were also investigated, to further justify its application feasibility.