Metal capture during fluidized bed incineration of solid wastes

Abstract

One of the current concerns associated with waste incineration is heavy metals, such as arsenic, barium, beryllium, chromium, cadmium, lead, mercury, nickel and zinc, because of their presence in many hazardous wastes and because of possible adverse health effects from human exposure to emissions. An incineration system which is capable of retaining metals during incineration is highly desirable because it greatly reduces the amount of metals in stack emissions. Of available incineration systems, fluidized bed incinerators appear to offer the best hope for metal capture during incineration. Specific data on the effectiveness of metal capture by various sorbents, however, are not available. In this study, experiments are carried out in a 7.62-cm (3″) fluidized bed incinerator to evaluate the effectiveness of lead capture by limestone during fluidized bed incineration of lead contaminated solid wastes. Experimental parameters include air flow rate, limestone size, waste-to-limestone ratio and incineration temperature. An atomic absorption analyzer is used to determine lead concentrations in both the original and the incinerated limestone. The results have indicated that limestone is capable of capturing lead during fluidized bed incineration. Small particle size, high turbulence and low temperature favor lead absorption.