Heat Generation in Municipal Solid Waste Landfills

Abstract

This study was conducted to investigate thermal aspects of municipal solid waste landfills as a function of operational conditions and climatic region. Spatial and temporal distributions of waste temperatures were determined at four landfills located in North America �Michigan, New Mexico, Alaska, and British Columbia�. Temperatures of wastes at shallow depths �extending to 6 to 8 m depth� and near the edges of a cell �within approximately 20 m� conformed to seasonal temperature variations, whereas steady elevated temperatures �23 to 57°C� with respect to air and ground temperatures were reached at depth and at central locations. Waste temperatures decreased from the elevated levels near the base of landfills, yet remained higher than ground temperatures. Thermal gradients in the range of approximately −30 to +22°C / m with average absolute values typically less than 5°C / m were measured within the wastes. Heat content �HC� of wastes was determined as the difference between measured waste mass temperatures and unheated baseline waste temperatures at equivalent depths. Peak HC values ranged from 12.5 to 47.8°C day/ day. The peak HCs were directly correlated with waste placement rates and initial waste temperatures, and they occurred at a specific average precipitation �2.3 mm/ day� beyond which further precipitation did not contribute to heat generation. HC was determined to conform to exponential growth and decay curve relationships as a function of climatic and operational conditions. Heat generation was determined based on HC using 1D heat transfer analysis. The heat generation values ranged from 23 to 77 MJ/ m 3 without losses and were significantly higher than biochemical prediction models, yet lower than values from incineration analyses. Overall, the highest values for temperatures, gradients, HC, and heat generation were observed in Michigan, followed by British Columbia, Alaska, and New Mexico. Integrated analysis of temperature and gas composition data indicated that temperature increases and HC values were greater during anaerobic decomposition than aerobic decomposition. Sustained high temperatures and heat generation occurred in wastes under anaerobic conditions.

Zero Waste: An Innovation for Less Polluting Emission Processes, Resource Management Practices and Policies

“…Under this condition organic matter will be degraded to humus substances. However, aerobic degradation will produce heat and as a result, temperature will rise in the landfill body (Yesiller et al, 2005) …”

“…The greenhouse gases emissions related to waste deposits are mainly due to methane (CH 4 ) and carbon dioxide (CO 2 ) present in the biogas produced by anaerobic bacteria using as carbon source the biodegradable carbon contained in the waste (Hoeks, 1983;Barlaz, Ham & Schaefer, 1990). In particular the disposal of waste in landfills generates methane that has high global warming potential (Yesiller, Hanson and Liu, 2005). Energy consumption contributes directly to climate change by adding carbon-based molecules to the atmosphere in excess of naturally occurring amounts.…”

Zero Waste: An Innovation for Less Polluting Emission Processes, Resource Management Practices and Policies

“…Global temperatures have increased as well (Yesiller et al, 2005). In particular the disposal of waste in landfills generates methane that has high global warming potential.…”

“…Under this condition organic matter will be degraded to humus substances. However, aerobic degradation will produce heat and as a result, temperature will rise in the landfill body (Yesiller et al, 2005). Source Reduction: This involves the reduction of waste through the alteration of manufacturing practices to reduce the creation of excess materials which get turned into waste.…”

“…The greenhouse gases emissions related to waste deposits are mainly due to methane (CH4) and carbon dioxide (CO2) present in the biogas produced by anaerobic bacteria using as carbon source the biodegradable carbon contained in the waste (Hoeks, 1983;Barlaz, Ham & Schaefer, 1990). In particular the disposal of waste in landfills generates methane that has high global warming potential (Yesiller, Hanson and Liu, 2005). Energy consumption contributes directly to climate change by adding carbon-based molecules to the atmosphere in excess of naturally occurring amounts.…”