Incinerator ash characterization - Implications for elevated temperature landfills

Area of Science:

• Environmental Science
• Geochemistry
• Materials Science

Background:

• Elevated temperatures in municipal solid waste (MSW) landfills, termed Elevated Temperature Landfills (ETLFs), are a significant concern in the solid waste industry.
• Co-disposal of MSW incinerator ash (MSWIA) and coal combustion ash (CCA) with unburned MSW can lead to exothermic reactions, contributing to these high temperatures.

Purpose of the Study:

• To characterize ash samples and assess their potential to generate heat when co-disposed in landfills.
• To develop a model for estimating the relative heat potential (RHP) of different ash types.

Main Methods:

• Characterization of sixteen ash samples using X-ray diffraction (XRD), X-ray fluorescence (XRF), and scanning electron microscopy with X-ray energy dispersive spectroscopy (SEM/XEDS).
• Development of a simple model to estimate the relative heat potential (RHP) based on ash composition.

Main Results:

• Identified complex mineral and glassy phases enriched in calcium, silicon, aluminum, and iron in the ash samples.
• Estimated RHP values indicated that CCAs may generate approximately 15% more heat than MSWIAs.
• The heterogeneous nature of ash, influenced by incineration and weathering, contributes to its heat-generating capacity.

Conclusions:

• Ash composition, particularly aluminum content, plays a crucial role in the heat generated within landfills.
• CCA has a higher potential for generating heat compared to MSWIA when co-disposed in landfills.
• Understanding these properties is vital for managing ETLFs and optimizing waste disposal strategies.