The Release Characteristic and Removal of Heavy Metal and HCl During Co-Combustion of MSW and Aged Refuse: A Preliminary Study Based on Thermodynamic Equilibrium Analysis

Co-combustion in a refuse incinerator is a primary method for treating aged refuse (AR). Given the high contents of heavy metals and chlorine in AR, it is crucial to investigate their release and fate during co-combustion to achieve environmentally sound treatment. This study investigated the release and volatilization of heavy metals (Cd, Cr, Zn, Ni, Cu, Pb) and HCl during the co-combustion of AR and municipal solid waste (MSW) through chemical thermodynamic equilibrium analysis. The effects of several parameters on the volatilization of heavy metals and HCl were analyzed, including incineration temperature, the N₂/O₂ ratio, the degree of refuse classification, the blending ratio of AR, and the effects of conventional calcium-based additives. The results showed that high temperature promoted the volatilization of Cd, Pb, Cu, Ni, and HCl. A lower N₂/O₂ ratio suppressed Zn and HCl volatilization. A higher degree of MSW classification (with lower proportions of kitchen and wood waste) and an increased AR blending ratio enhanced Zn fixation. CaO at high temperature only suppressed HCl volatilization, with a minor effect on heavy metals. Two modified calcium-based additives (CaBSiO₄OH and CaB₅SiO₉(OH)₅) with strong high-temperature Cu removal capabilities were explored, and their risk index was analyzed.