13C.1 INTRODUCTION

Combustion of wastes has long been recognized as a final disposal solution, because the organic matter is destroyed and only solid residues remain. By comparison, land-filling is a solution that amounts to storage, with the continuing risk of unwanted consequences (Taylor, 1992; Jones, 1994).

As of the year 2000, over 90 percent of municipal waste is combusted in Japan, 75 percent in Europe, where landfill of organic matter is essentially prohibited. In the United States, only 15 percent is combusted although in some states, it approaches 50 percent: the low cost competition of landfills has been a major factor in limiting combustion. Moreover, in the United States properly designed and maintained landfills are accepted by regulatory authorities. Emissions from landfills can be higher than those from waste combustion facilities, and collection of landfill gases has increasingly become a regulatory requirement (IWSA, undated).

Waste combustion results in discharge of gaseous and particulate matter to the atmosphere and causes public concern for health and the environment. In order to take advantage of combustion technology, great efforts and continuous evolution have been applied to minimize negative affects. In addition, it is necessary to dispose of the solid residues of combustion which have the potential for harm if not properly managed, mainly due to the solubility of metals, and the risk that they potentially impose on the environment. Management of the ash residues is treated in Sec. 13C.2.

To gain and maintain public acceptance for combustion of wastes, it has...