Evaluation of carbonated incineration bottom ash using exhaust gas and CO2 discharged from waste incineration facilities as ground material

Abstract

This study focused on a carbonation treatment that immobilizes trace elements such as lead (Pb) in incineration bottom ash (IBA) using the exhaust gas and the refined carbon dioxide generated (CO2) recovered at the Japan's first incineration facility, which recovers CO2 in the gaseous form. This study describes (1) the bearing capacity of IBA from the municipal solid waste (MSW) obtained through the California bearing ratio (CBR) test to investigate the possibility of using IBA as a base course material, (2) mechanical characteristics of IBA using the cone index test, to investigate the possibility of using as an embankment material, and (3) leaching properties of IBA from MSW obtained through a single batch leaching test and the long-term outdoor exposure of the leaching test to evaluate the effect of carbonation treatments. Results reveal that there was no effect of trace components not included in the separated and recovered CO2, and that the effect of carbonation could be obtained even if the exhaust gas was used directly. The carbonated IBA can be applied as a sub-base course material based on its mechanical properties, regardless of the carbonation conditions. In addition, carbonated IBA can be used as an embankment material owing to its sufficient cone index value. Regarding the heavy metal and metalloid leaching behavior, it was revealed that all the IBA samples satisfied the soil environmental standards set by the Ministry of the Environment, Japan, except for Cr (VI). The long-term leaching characteristics of carbonated IBA showed that Pb could be immobilized over a long period.