In North America, temperatures nearing 100°C have been reported in a few municipal solid waste landfills. Elevated temperature landfills have unique characteristics and challenges including substantial changes in the composition and quantity of landfill gas and leachate, rapid waste subsidence, and, in some cases, elevated liquid and gas pressures. Using a batch reactor model that was developed to estimate temperatures in landfills in consideration of biological and chemical reactions, we estimated that the presence of 1.7% elemental aluminum (Al) in a landfill would result in a temperature rise of 26°C in 10 years relative to a case with MSW only and assuming 100% corrosion of the elemental Al. However, the Al corrosion rate data were adopted from the literature on systems other than landfills. The objectives of this study are to develop a methodology to investigate the rate and extent of Al corrosion under landfill-relevant conditions and to use the resulting landfill-relevant corrosion rate to parameterize the batch and 3D landfill heat models. A number of variables are being tested including the impacts of the major constituents of leachate (chloride ions, ammonia, volatile fatty acids, humic substances), pH, temperature (50,70°C) and the type of aluminum (foil, cans, sheet). Tests are being conducted in a batch system (0.16 L serum bottles) with selected tests also conducted in a 5-L reactor system in the presence of a cellulosic substrate. H2 generation was used to calculate the rate and extent of Al corrosion. Fig. 1a shows the impacts of major constituents of leachate on the Al corrosion rate as represented by H2 yield. The results indicate that humic substances (HS) inhibit the rate of Al corrosion. Fig.1b illustrates the impact of the source of HS on Al corrosion by using 3 commercially available HS obtained from Sigma Aldrich (Sig), Acros (ARC) and Beantown Chemical (BTC). The rate of Al corrosion in the HS from BTC was 3 to 4 orders of magnitude greater than that of other HS, indicating that Al corrosion is sensitive to the source of HS. As a result, subsequent work was conducted with landfill leachates from multiple sources.

Experimental measurement of heat production from Al corrosion under landfill-relevant conditions

ACS Spring 2022

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