| Summary: | 碩士 === 國立中央大學 === 環境工程研究所 === 82 === Due to its dense population, limited land for waste disposal,
and increases in per capita waste generation, Taiwan is
entering a phase of applying incineration technology as an
alternative to landfills for municipal solid waste (MSW)
management. However, the potential emission of toxic heavy
metals from MSW incinerators into the environment may pose
serious threats on human health and ecology. This issue has not
been properly addressed and has caused more public concerns in
Taiwan recently since the concept of separation and recycling
of refuse is not generally adopted and the incinerators for
hazardous wastes are not commonly available here. In this
study, the concentrations of some heavy metals (including Hg,
Cd, Pb, and Zn) which exist in fly ash and bottom ash coming
out of a typical MSW incinerator located in northern Taiwan
were determined. Furthermore, the physical properties, such as
particle size, surface area, and porosity of fly ash were also
characterized for better understanding of their potential
effects on the concentration of these heavy metals. Preliminary
results indicate that the concentrations of mercury, cadmium,
and zinc are generally higher in fly ash than that found in
bottom ash. In fact, the property of municipal solid wastes,
varying operating conditions within incinerators, combustion
efficiency, and chloride content in the flue gas streams all
affect the partitioning of heavy metals among flue gas, fly ash
and bottom ash. As a result, the concentration of heavy metals
contained in fly ash may vary with different particle size. In
this study, collected fly ash was segregated into seven
different fractions based on particle size (Mesh 50-Mesh 325).
Analysis of particles with each fraction indicates that
particles around Mesh 50/80 with a specific area of about 6 m2/
g tend to adsorb more heavy metals (including Hg, Cd, Pb, and
Zn) than the particles with other sizes.
|
|---|
