Cent Eur J Public Health 1998, 6(2):79-87
Chemical aspects of combustion of hazardous wastes
- University of Dayton, Dayton, Ohio, USA
As a treatment option for hazardous wastes, incineration or thermal treatment is efficient and cost effective. However, there has been a long-standing concern over emissions of undestroyed waste and toxic combustion by-products. Much of this concern is a result of lack of understanding of the types of by-products that can be formed and their origin. This manuscript presents a zone model of incineration that can be used as a context in which to describe pollutant formation pathways. Five zones are identifies: the pre-flame zone, the post-flame thermal zone, the gas-phase quench zone, and the surface catalysis cool zone. It is shown that most combustion by-products are actually the result of thermal zone and surface catalysis zone chemistry. The manuscript categorizes and summarizes the various elementary reactions that can occur in each zone and identifies their relative importance in pollutant formation pathways. Molecular growth reactions that form polycyclic aromatic hydrocarbons (PAH) and chlorinated PAH are largely the result of gas-phase reactions in the thermal zone. However, surface catalyzed reactions may be the major source of most observed organic pollutant emissions. In addition to the documented role of surfaces in forming dioxins and furans, surfaces may catalyze the formation of many other chlorinated hydrocarbons (CHCs) and oxy-hydrocarbons. The discussion may be used as a guide for predicting and assessing emissions from a range of thermal treatment devices.
Published: June 1, 1998 Show citation