Geotechnical characteristics of carbonated incineration bottom ash using exhaust and CO2 discharged from waste incineration facilities

In Japan, approximately 4 million tons of incineration bottom ash (IBA) from municipal solid waste (MSW) are discharged a year. Since Japan does not have enough space to bury this material in landfills, it is necessary to reuse IBA. However, since bottom ash includes toxic material, immobilization is needed for effective use. This study is focused on carbonating treatments that immobilize bottom ash by exhaust gas (EG) and carbon dioxide (CO2) generated from the Saga city incineration plant. In this incineration plant, CO2 is separated and collected from EG generated when garbage is incinerated; this is Japan's first carbon dioxide capture and utilization (CCU) plant at a waste incineration facility. The mechanical characteristics and leaching properties of carbonated IBA for use as construction materials, such as base course or embankment materials are determined in tis study using the California bearing ratio (CBR) test, cone index, and leaching tests. As a result, it was revealed that carbonated IBA can be reused as a subbase course material. Also, the leaching concentrations of heavy metals from carbonated IBA were influenced by carbonating treatment processing and its immobilization effect was higher in CO2 than in EG. It was also revealed that the concentration of lead meets the environmental quality standard values for soils set by the Japanese Ministry of the Environment.