Impact of Municipal Solid Waste (MSW) Quality on the Behavior of Alkali Metals and Trace Elements during Combustion: A Thermodynamic Equilibrium Analysis

Municipal solid waste (MSW) is a complex fuel. To study the impact of its composition on speciation during incineration, a novel approach consisting of studying separate waste fractions with the help of thermodynamic equilibrium calculations is used. The focus is on the behavior of alkalis, Pb, Zn, trace elements (As, Cr, and Cd), Cl, and S. The calculations show that (i) the concentration and thermodynamic properties of a given chemical element impact its speciation differently in different waste fractions, (ii) the chemistry of ash and trace elements in different fuels can be similar regarding behavior and speciation, (iii) ratios related to input parameters allow for a better understanding of elemental chemistry, (iv) some chemical elements have a versatile chemistry, i.e., shifting widely with fuel composition, such as Zn, while some others do not (Cr), and (v) S and Cl chemistries are strongly linked. Taking into account interactions between two waste fractions during incineration may have negative consequences (such as increased corrosion) but may also produce synergies mitigating operational challenges.