Assessing the Chemical Behavior of Metals in Municipal Solid Waste Incineration Fly Ash Using an Enhanced CO2 Absorption

CO2 absorption was used to stabilize heavy metals in fresh fly ash from a municipal solid waste incinerator and achieved the aim of using waste to treat waste. The influence of fundamental parameters affecting the stabilization of heavy metals and the changes in the fly ash with carbonation was evaluated. Results indicated that different elements [cadmium (Cd), chromium (Cr), lead (Pb), zinc (Zn), arsenic (As), copper (Cu), iron (Fe), and silicon (Si)] showed different release curves in the pH range of 0-13 and pH value played an important role in leaching behavior of municipal solid waste incineration (MSWI) fly ash. Addition of 10-50% of water markedly accelerated the stabilization of Pb, Zn, and Cu in MSWI fly ash through the carbonation process. When the carbon dioxide (CCO2) partial pressure was 50%, the degree of carbonation was satisfied. Results of the X-ray diffraction (XRD) analysis and the sequential extraction procedure indicated that CO2 could combine with Ca(OH)(2) to form CaCO3 and that carbonation changes modality characteristics of some heavy metals in fly ash from exchangeable form to carbonated combination forms.