Behavior of metals in municipal-sludge incinerators

The emission of toxic metals from sewage sludge incinerators can present a risk to human health and the environment. A significant base of data on the behavior of metals in sludge incinerators has been compiled. These data were examined in detail to identify the mechanisms responsible for metals emissions and determine the effect of key operating parameters. The primary metals escape mechanism identified involved the vaporization of metals in the combustion zone and subsequent condensation in the exhaust system. The process significantly increases the concentration of toxic metals on submicron particles. Combustion chamber temperature was found to have a strong effect on metals emissions. No relationship could be observed between total particulate emissions and metals emissions.