Effects of Placement Conditions on Decomposition of Municipal Solid Wastes in Cold Regions

Abstract

The effects of placement practices on decomposition of wastes were investigated at Anchorage Regional Landfill (Anchorage, Alaska) since 2002. Temperatures and gas concentrations of wastes placed at various seasons were monitored. Wastes were placed at sub-freezing temperatures during cold seasons. Waste temperatures generally increased upon placement.High variation was observed in waste temperatures near the surface whereas steady temperatures were obtained at depth. High maximum stable temperatures resulted from warm placement conditions. Steady temperatures between approximately -1 to +35°C were observed. The central portion of a frozen waste band (with a total initial thickness of 7 m at placement, currently between depths of approximately 8 m to 15 m) remains frozen 2 years after placement. Both the top and bottom regions of the frozen waste band have thawed. Heat Content (HC) varied between -8.2 (for 2-year-old waste at a depth of 11.9 m in frozen wastes) to +25.9°C-day/day (for 13-year-old waste at a depth of 32 m for waste placed in summer). The measured frost depths in waste ranged from 0.7 to 1.3 m and were less than that for native soil at the landfill site. Instantaneous thermal gradients ranged from -73 to +60°C/m. Gas concentrations were similar to air at the time of waste placement. Anaerobic decomposition conditions and onset of landfill gas production started within 3 to 4 years of placement for wastes placed during warm seasons. Virtually no decomposition or gas generation were observed in the frozen wastes. A 1-D numerical model was used to investigate distribution of temperatures for placement at varying temperatures and for varying lift thicknesses. It is recommended to minimize frozen lift thicknesses to obtain higher temperatures.

Waste heat generation: A comprehensive review

“…A temperature range of 40-45°C was identified as the optimum range for gas production at a landfill in England (Rees, 1980a,b) with highly inhibited and delayed gas http://dx.doi.org/10.1016/j.wasman.2015.04.004 0956-053X/Ó 2015 Elsevier Ltd. All rights reserved. generation observed at low waste temperatures (Hanson et al, 2006). Biomass transfer was reported to occur with landfill gas, where the cell counts in the gas were correlated to temperature (Barry, 2008).…”

Simulating waste temperatures in an operating landfill in Québec, Canada

“…The results of the model to date confirm landfill operators should consider staging waste placement to avoid placing consecutive frozen waste lifts in succession (Hanson et al, 2006;Houi et al, 1997;Vingerhoeds, 2011). For example, the effects of settlement should be incorporated in the model, as settlement will cause the thermal characteristics of the waste to change over time.…”

“…Many bioreactor landfills have been instrumented with sensors to monitor the stabilization process in order to evaluate the effectiveness of the bioreactor technology (Augenstein et al, 1997;Hunte et al, 2011;Reinhart et al, 2002;Yesiller et al, 2011;Zhao et al 2008;). However, the majority of the previous modelling efforts simulate bioreactor landfill operation in warmer climates; cold temperatures in northern climates can significantly affect waste stabilization (Hanson et al, 2006;Zhao et al 2008). However, the majority of the previous modelling efforts simulate bioreactor landfill operation in warmer climates; cold temperatures in northern climates can significantly affect waste stabilization (Hanson et al, 2006;Zhao et al 2008).…”

“…Instrumentation of landfills in northern climates has been implemented by researchers in Alberta (Davies and Colbran, 2010;Hunte et al, 2011), Alaska (Hanson et al 2006) and Michigan (Zhao et al, 2006(Zhao et al, , 2008. At the Northern Oaks Recycling and Disposal Facility in Harrison, MI, USA, results from temperature and gas composition data showed the first lift of waste placed in the summer months was degrading actively and produced high concentrations of methane gas, whereas waste placed during the winter months remained frozen for 6 months post-closure (Zhao et al, 2008).…”

Heat Transfer Model for an Engineered Landfill in Sainte-Sophie, Quebec, Canada

“…Faitli et al (2014) recently developed laboratory testing on MSW from a landfill in Hungary and measured the specific heat to range from 900 J/kgK to 2100 J/kgK. In the literature, the specific heat value ranged from 719 J/kgK to 2360 J/kgK (Hanson et al, 2006;Yoshida et al, 1997).…”