Study on the synergistic removal of chlorine and heavy metals during the Co-combustion of aged refuse and municipal solid waste by modified calcium-based additives

A central challenge in co-combustion of aged refuse is suppressing the synergistic release of heavy metals and HCl in high-temperature flue gas. To address the limitations of conventional Ca-based additives, three modified Ca-based sorbents doped with Si, B, and P (CA-I, CA-II, CA-III) were developed. Their structural properties were systematically characterized. Removal efficiency for HCl and six heavy metals (Cd, Cr, Zn, Ni, Cu, Pb) was evaluated between 650°C and 950°C, along with an assessment of ecological risk from heavy metals. CA-II exhibited the highest specific surface area, while CA-III showed stable adsorption above 750°C and significantly reduced ecological risk, with Cd and Zn identified as key risk elements. The optimal additive dosage was 5% to avoid agglomeration. This study provides a novel design strategy and fundamental data for synergistic control of pollutants and ecological risk during co-combustion.Implication: This study offers a viable engineering solution for the synergistic control of HCl and heavy metals during waste co-combustion, providing practitioners with a high-efficiency, high-temperature adsorbent (CA-III). From a policy perspective, the technology significantly reduces ecological risks – particularly for Cadmium and Zinc – by stabilizing toxic pollutants, thereby supporting “zero-waste city” initiatives and helping to mitigate public opposition (NIMBY) to incinerators. These findings provide scientific evidence to promote the use of phosphorus-modified additives in solid waste management regulations, facilitating the safe energy recovery of aged landfill refuse and improving the sustainability of waste-to-energy operations.