Porous Ca-based bead sorbents for simultaneous removal of SO₂, fine particulate matters, and heavy metals from pilot plant sewage sludge incineration

In this study, a porous calcium-based sorbent was prepared for simultaneous removal of SO₂, particulate matter (PM), and heavy metals generated during incineration of sewage sludge. The prepared sorbent was confirmed to have a 3-dimensional-network pore structure, a high specific surface area of 68.5m²/g, and gas permeability of 1.12×10^-10m². Laboratory-scale tests indicated that there was an improvement in the performance of SO₂ removal as the porosity and the specific surface area of the sorbent increased. Additionally, increasing reaction temperature led to greater SO₂ removal. Meanwhile, the SL-4 and LS-3 sorbents prepared in this study were installed for operation during pilot tests treating the sewage sludge combustion gas generated by a fluidized incinerator in order to compare and evaluate their feasibility for use in industrial applications. The results showed that the reactivity between SO₂ and the starting material of the sorbent (Ca(OH)₂>CaCO₃), as well as the high specific surface area of the sorbent, were confirmed to be critical factors that improved the performance of SO₂ removal. Notably, the results confirmed that both fine PM (≤1μm) and heavy metals were simultaneously removed with increasing efficiency over the time of operation.