Waste heat generation: A comprehensive review

Abstract

A comprehensive review of heat generation in various types of wastes and of the thermal regime of waste containment facilities is provided in this paper. Municipal solid waste (MSW), MSW incineration ash, and mining wastes were included in the analysis. Spatial and temporal variations of waste temperatures, thermal gradients, thermal properties of wastes, average temperature differentials, and heat generation values are provided. Heat generation was influenced by climatic conditions, mean annual earth temperatures, waste temperatures at the time of placement, cover conditions, and inherent heat generation potential of the specific wastes. Time to onset of heat generation varied between months and years, whereas timelines for overall duration of heat generation varied between years and decades. For MSW, measured waste temperatures were as high as 60-90°C and as low as -6°C. MSW incinerator ash temperatures varied between 5 and 87°C. Mining waste temperatures were in the range of -25 to 65°C. In the wastes analyzed, upward heat flow toward the surface was more prominent than downward heat flow toward the subsurface. Thermal gradients generally were higher for MSW and incinerator ash and lower for mining waste. Based on thermal properties, MSW had insulative qualities (low thermal conductivity), while mining wastes typically were relatively conductive (high thermal conductivity) with ash having intermediate qualities. Heat generation values ranged from -8.6 to 83.1MJ/m(3) and from 0.6 to 72.6MJ/m(3) for MSW and mining waste, respectively and was 72.6MJ/m(3) for ash waste. Conductive thermal losses were determined to range from 13 to 1111MJ/m(3)yr. The data and analysis provided in this review paper can be used in the investigation of heat generation and thermal regime of a wide range of wastes and waste containment facilities located in different climatic regions.

Heat management strategies for MSW landfills

“…Significant amounts of heat are generated in different types of waste containment facilities including municipal solid waste (MSW) landfills, landfills that are used solely to contain municipal solid waste incinerator ash, and mining waste piles (Yeşiller et al 2015a). Heat generation occurs due to bacterially mediated decomposition of the organic fraction of the waste materials and also due to chemical and biochemical reactions that occur within the wastes.…”

“…An extensive review of heat generation in MSW landfills and other types of containment facilities was provided in Yeşiller et al (2015a). In MSW landfills, waste temperatures tend to increase over a period of months to years until reaching steady elevated temperature conditions (as compared to ambient ground temperatures) generally at the central regions of the waste mass.…”

The impacts of temperature and thermal properties on municipal solid waste stabilization

“…Mesophilic and thermophilic bacteria are responsible for anaerobic biodegradation, and each operate under different temperature regimes. Mesophilic bacteria are those involved in waste degradation at mid range temperatures of 35 to 40 • C (Lefebvre et al, 2000;Yesiller et al, 2005Yesiller et al, , 2015, 35 • C (Lee, 1996), 20 to 44 • C (Farquhar & Rovers, 1973). Thermophilic bacteria are those involved in waste degradation at higher temperatures of 50 to 60 • C (Lefebvre et al, 2000;Yesiller et al, 2005Yesiller et al, , 2015, 55 to 60 • C (Lee, 1996), 44 • C and greater (Farquhar & Rovers, 1973),…”

“…Table 2.2 provides a summary table of the thermal conductivity and specific heat values found in the literature. (Hanson et al, 2000;Yesiller et al, 2015). It is common to have void spaces of air throughout MSW, which significantly lowers the thermal conductivity since air has a lower thermal conductivity than MSW (Faitli et al, 2014).…”

“…Heat (as well as leachate and landfill gas) is a primary by-product of MSW landfills and is generated as a result of biological activity within the landfill (El-Fadel et al, 1996a;Hanson et al, 2013;Yesiller et al, 2005Yesiller et al, , 2015. Heat gain within a landfill can be directly related to gas generation (El-Fadel et al, 1997a).…”