Atmospheric Emissions of Metals from Sewage Sludge Incineration

Abstract

Increased emphasis is being placed on incineration of sewage sludge at higher temperatures to insure complete destruction of organic compounds. Increasing the combustion temperature, however, increases the potential emissions of volatile metals such as cadmium and lead. The data presented, which were compiled from a review of the literature, indicate an increase in the percent of metals emitted to the atmosphere with rising temperatures in the 700° to 930°C (1300° to 1700°F) range for both multiple-hearth and fluidized-bed sludge incinerators. It appears that especially arsenic, cadmium, mercury, zinc, and some lead compounds may be emitted in larger amounts with increasing combustion temperatures. Combined with this trend is the fact that volatilized metals tend to condense as submicron particulafe or as a fume which is more difficult to capture with commonly used control devices. More investigation is needed on innovative control devices and their effect on submicron metal emissions from this type of source, especially at higher combustion temperatures. This report focuses on summarizing available metals emission data from sewage sludge incinerators and noting the air pollution control problems evidenced by this data. © Taylor & Francis Group, LLC.