Immigration, transformation, and emission control of sulfur and nitrogen during gasification of MSW: Fundamental and engineering review

This paper proposes a comprehensive summary and analysis of an important issue during municipal solid waste (MSW) gasification-sulfur and nitrogen pollution. It provides an overview of the fundamentals of MSW and the basic aspects of nitrogen and sulfur elements. Their characteristics of immigration, transformation and distribution during gasification with control solutions in realized or potential engineering are also concluded. The analysis indicates that the complete scenario of the occurrence form of sulfur and nitrogen elements in MSW is difficult to obtain, owing to the diverse sources and complicated compositions. However, with the assistance of advanced characterization and quantification methods (XPS, XRD, TG-FTIR, et al.), the common sulfur- and nitrogen-containing compounds in both organic and inorganic states can be detected. Adjustment of gasification conditions can regulate the transformation of these elements for emission control. The multiple pollutants including H₂S, SO_x, COS, NH₃, HCN and NO_x cannot be eliminated by one-step treatment but a combination of adsorption and catalytic treatments may realize the control goal. This research aims to benefit meeting emission standards during MSW gasification and to provide a reference for other processes such as incineration, pyrolysis and other feedstocks like biomass and refuse derived fuel (RDF).