Pb stabilization in fresh fly ash from municipal solid waste incinerator using accelerated carbonation technology

Carbonation technology with CO2 absorption was used to enhance the stabilization of heavy metals in fresh fly ash from a municipal solid waste incinerator (MSWI). The influence of fundamental parameters affecting the stabilization of heavy metals, especially Pb and diffusivity and reactivity of CO2, was evaluated. The results indicated that the addition of 10% or more of water could remarkably accelerate the absorption of CO2 and could also accelerate the stabilization of MSWI fly ash. The stabilization of MSWI fly ash is not distinct within 1 d in the air atmosphere for low content of CO2 (0.03%). The result of the XRD analysis indicated that CO2 could combine with Ca(OH)2 to form CaCO3 and CO2 could also combine with heavy metal oxide to form heavy metal carbonate in the adsorption of CO2. The TGA analysis showed that MSWI fly ash has the sequestration capability of 3% (w/w) CO2. The sequestration of CO2 has a large impact on Pb, and the exchangeable Pb can be converted into carbonated form in rich CO2 condition to be stabilized.