Numerical simulation of landfill gas pressure distribution in landfills

Xi, Yang; Xiong, Hao

doi:10.1177/0734242x13502380

“…Overpressure corresponds to a decrease in atmospheric pressure, and causes the emission of gas from a landfill. Therefore, the rate of the barometric pressure variations is an important factor to consider when sampling and analyzing gas emissions (Nastev et al, 2001;Xi and Xiong;Xu et al, 2012). However, Fredenslund et al (2010) suggested that this relationship is more complex than a simple linear function.…”

Section: Influences Of Gauge Pressure On Methane Emission Flux and Concentrationmentioning

confidence: 99%

Estimation of methane emission flux at landfill surface using laser methane detector: Influence of gauge pressure

Park¹,

Kang²,

Lee

³

2016

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The aim of this study was to investigate the possibility of measuring methane emission fluxes, using surface methane concentration and gauge pressure, by analyzing the influence of gauge pressure on the methane emission flux and the surface methane concentration, as well as the correlation between the methane emission flux and surface methane concentrations. The surface methane concentration was measured using a laser methane detector. Our results show a positive linear relationship between the surface methane concentration and the methane emission flux. Furthermore, the methane emission flux showed a positive linear relationship with the gauge pressure; this implies that when the surface methane concentration and the surface gauge pressure are measured simultaneously, the methane emission flux can be calculated using Darcy's law. A decrease in the vertical permeability was observed when the gauge pressure was increased, because reducing the vertical permeability may lead to a reduced landfill gas emission to the atmosphere, and landfill gas would be accumulated inside the landfill. Finally, this method is simple and can allow for a greater number of measurements during a relatively shorter period. Thus, it provides a better representation of the significant space and time variations in methane emission fluxes.

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“…( 2 )–( 6 ) into Eq. ( 1 ), since the pressure of landfill gas is a very small value compared with the atmospheric pressure, then the pressure of landfill gas can be neglected when the sum of the gas pressure in landfills and the atmospheric pressure is calculating 29 , 30 , 32 , 33 . The gas pressure distribution in the landfill is a one-dimensional problem, because the landfill gas is only considered to migrate to the outside and into the old waste layer.…”

Section: Methodsmentioning

confidence: 99%

Simulation of gas transport in a landfill with layered new and old municipal solid waste

Zhang

¹

,

Shi

²

,

Wu

³

et al. 2021

Sci Rep

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Average biodegradation rate of newly filled municipal solid waste (MSW) in landfills is relatively fast, and the landfill gas produced by the new MSW biodegradation can cause great variations in gas pressure. To predict the gas pressure distribution in the MSW layer, a one-dimensional gas transport model is established in this study. The following factors are considered in this model: (1) the variation of gas permeability with depth; (2) the anisotropy ratio of gas permeability; (3) the settlement caused by waste biodegradation. Furthermore, a single peak model for gas production is applied as the source term of gas production. The equation for settlement caused by waste biodegradation is presented, and the time of peak gas production rate is obtained by fitting the settlement of the newly filled layer. The stratification of the unsaturated and saturated regions is taken into account by distinguishing the difference in gas saturation. The layering of the new and old waste layers is considered by distinguishing the difference in the length of time that waste has been degraded to produce gas. Based on the method of numerical calculation, the gas pressure distribution in the landfill with layered new and old MSW is well simulated. The position where the maximum gas pressure occurs is found. The sensitivity analysis shows that the influence of the anisotropy ratio on gas pressure distribution is more significant.

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“…where λt is waste biodegradation rate; ms0 is the waste mass at the initial moment; mst is the waste mass at the moment t; Vs0 is the waste volume at the initial moment; Vst is the waste volume at the moment t; h0 is the initial height of landfill; ht is the height of landfill at time t; e0 is the initial void ratio; et is the void ratio at time t. 2) -( 6) into Eq. (1), since the pressure of landfill gas is a very small value compared with the atmospheric pressure, then the pressure of landfill gas can be neglected when the sum of the gas pressure in landfills and the atmospheric pressure is calculating [29][30][32][33] . The gas pressure distribution in the landfill is a one-dimensional problem, because the landfill gas is only considered to migrate to the outside and into the old waste layer.…”

Section: Numerical Model For Gas Transportmentioning

confidence: 99%

Simulation of Gas Transport in A Landfill With Layered New and Old Municipal Solid Waste

Zhang

¹

,

Shi

²

,

Wu

³

et al. 2021

Preprint

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Average biodegradation rate of newly filled municipal solid waste (MSW) in landfills is relatively fast, and the landfill gas produced by the new MSW biodegradation can cause great variations in gas pressure. To predict the gas pressure distribution in the MSW layer, a one-dimensional gas transport model is established in this study. The following factors are considered in this model: (1) the variation of gas permeability with depth; (2) the anisotropy ratio of gas permeability; (3) the settlement caused by waste biodegradation. Furthermore, a single peak model for gas production is applied as the source term of gas production. The equation for settlement caused by waste biodegradation is presented, and the time of peak gas production rate is obtained by fitting the settlement of the newly filled layer. The stratification of the unsaturated and saturated regions is taken into account by distinguishing the difference in gas saturation. The layering of the new and old waste layers is considered by distinguishing the difference in the length of time that waste has been degraded to produce gas. Based on the method of numerical calculation, the gas pressure distribution in the landfill with layered new and old MSW is well simulated. The position where the maximum gas pressure occurs is found. The sensitivity analysis shows that the influence of the anisotropy ratio on gas pressure distribution is more significant.

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Numerical simulation of landfill gas pressure distribution in landfills

Cited by 15 publications

References 20 publications

Estimation of methane emission flux at landfill surface using laser methane detector: Influence of gauge pressure

Estimation of methane emission flux at landfill surface using laser methane detector: Influence of gauge pressure

Simulation of gas transport in a landfill with layered new and old municipal solid waste

Simulation of Gas Transport in A Landfill With Layered New and Old Municipal Solid Waste

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