Fly ash treatment by desalination couples with solidification of heavy metals

Fly ash is the solid by-product of waste incineration. It contains high content of soluble salts and heavy metals, which causes difficulty in treatment. In this study, desalination coupled with heavy metal solidification is investigated for the treatment of fly ash from hazardous waste incineration. The distribution of salt and heavy metal and the leaching toxicity of heavy metal were detected. Sintering not only reduces the bulk density of fly ash but also can reduce heavy metal leaching toxicity. For instance, the soluble heavy metal was reduced by 95.4% after 700 °C sintering. The bulk density of fly ash increases from 0.295 g/cm3 to 1.046 g/cm3 after treatment, which significantly save the space of landfill. Meanwhile, the treated ash can meet the leaching limit of heavy metals for the flexible landfill in China. This research is meaningful for fly ash treatment industry and the sustainable development of waste incineration industry.