Abstract
Due to coal’s availability and low cost, coal combustion continues to be the United States’ primary energy source. However, coal combustion produces large quantities of waste material. Some coal combustion by-products (CCBs) have chemical and physical characteristics that make them potentially useful as soil amendments. The objectives of this study were to characterize a relatively new, high-calcium dry flue gas desulfurization (DFGD) by-product and compare its agronomic liming potential to a Class-C fly ash (FA) and reagent-grade calcium carbonate (CaCO3). Calcium car-bonate equivalence (CCE), degree of fineness (DOF), and effective neutralizing value (ENV) for each CCB were determined using standard methods. The CCBs and CaCO3 were also incubated with an acidic (~4.5) clay sub-soil at application rates equiva-lent to 0, 0.5, 1, and 2 times the soil’s lime requirement and compared to an una-mended control. Soil pH was then measured periodically during a 40-day incubation. The ENV of 79.4% for the DFGD by-product and 57.3% for the FA were comparable to those of commercially available liming materials, but were significantly lower (P
Highlights
Coal combustion for energy production accounted for 39% of the 3.9 billion kilowatthours of electricity generated in the United States in 2014 [1]
Continuous application of either the dry flue gas desulfurization (DFGD) by-product or Class-C fly ash (FA) may cause an increase in soil EC and limit growth for plants that are sensitive to saline soils [10]
Millions of megagrams of coal combustion by-products (CCBs) are disposed of in landfills and surface impoundments, which increases the likelihood of accidental releases to the environment
Summary
Coal combustion for energy production accounted for 39% of the 3.9 billion kilowatthours of electricity generated in the United States in 2014 [1]. In 2008, it was estimated that more than 123 million Mg of coal combustion by-products (CCBs) were produced, making CCBs the second largest waste stream in the United States behind municipal solid waste [2]. In 2007, only 44% of the CCBs generated in the United States were beneficially reused, which left 68 million Mg to be disposed of in landfills or surface impoundments [3]. As of 2012 in the United States, 310 active on-site landfills and 735 on-site surface impoundments were used to dispose of CCBs that were not beneficially reused [4]
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