Investigation of methane fluxes from temporary cover of Xi’an Jiangcungou landfill, China

WangQiao,; FeiShuangke,; WangLiang,; Bouazza, Abdelmalek; ShenSiliang,; XieHaijian,

doi:10.1680/jenge.19.00224

Cited by 7 publications

(7 citation statements)

References 55 publications

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“…Understanding the stress-dependent water retention curve (WRC) of intact loess is essential for addressing many geotechnical problems in loess regions, such as rainfall-induced excessive embankment settlement [1][2][3], failure of landfill cover system [4][5][6] and slope instability [7,8]. Thus, some experimental studies have been carried out in this area.…”

Section: Introductionmentioning

confidence: 99%

Effects of In-Situ Drying–Wetting Cycles on the Stress-Dependent Water Retention Behavior of Intact Loess

Shi

et al. 2023

Advances in Civil Engineering

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Understanding the effects of in-situ drying–wetting pattern on the stress-dependent water retention curve of intact loess is vital for addressing geotechnical problems in loess regions. The principal objective of this study is to investigate the influence of in-situ drying–wetting on the stress-dependent water retention behavior of intact loess. To meet this objective, six drying–wetting tests were carried out using a suction- and stress-controlled pressure plate extractor. Intact loess was sampled from three different depths: 1.0, 3.0, and 5.0 m. For specimens from each depth, two vertical net stresses (i.e., 0 and 50 kPa) were applied prior to the drying–wetting cycle. Experimental results revealed that the in-situ drying–wetting pattern greatly affected various aspects of the water retention behavior, particularly the hysteresis. The hysteresis of the specimen from 5.0 m is about 82% and 77% larger than that of the specimens from 1.0 and 3.0 m, respectively. This is because the specimen from 5.0 m has some large-size pores (i.e., >400 μm), which were not found in specimens from 1.0 and 3.0 m. These large-size pores enhance pore nonuniformity and hence the hysteresis. Furthermore, specimens from different depths consistently showed a reduction of hysteresis when the stress was increased from 0 to 50 kPa. The reduction is the most significant for a specimen from 5.0 m due to the collapse of large-size pores under compression.

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Section: Introductionmentioning

confidence: 99%

Effects of In-Situ Drying–Wetting Cycles on the Stress-Dependent Water Retention Behavior of Intact Loess

Shi

et al. 2023

Advances in Civil Engineering

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“…The capacity of the Tedlar bag for gas collection is 0.5 L, which accounts for 0.72% of the volume of the chamber. Therefore, it is reasonable to assume that volume change in the chamber induced by gas collection in the bag can be neglected (Wang et al, 2020 ). Both pumps (GP-2000) and Tedlar bags were provided by Huibin Instrument Company (Shanghai, China).…”

Section: Methodsmentioning

confidence: 99%

“…All the valves were then shut off to allow gas to accumulate in the chamber. The sealing process can effectively prevent gas exchange between the chamber and the atmosphere (Wang et al 2020 ). There was no air bubble in the water observed during the test, which indicates that the seal was good.…”

Section: Methodsmentioning

confidence: 99%

“…The meteorological data, including wind speed, humidity, temperature, and atmospheric pressure, during the field monitoring tests obtained from the local meteorological bureau are shown in Table 1 . It should be pointed out that extensive studies have demonstrated that the surface gas emission fluxes may exhibit prominent spatial and temporal variations as landfill gas emissions may be largely affected by waste age, cover types, components of wastes and landfill management strategies (Pierini et al 2018 ; Wang et al 2020 ; Duan et al 2021 ). The organic content, porosity and water distribution in cover soils can affect the reaction rate and migration of gases in the system.…”

Section: Applications Of the Model In A Field Studymentioning

confidence: 99%

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Numerical model for static chamber measurement of multi-component landfill gas emissions and its application

Xie

Zuo

Chen

et al. 2022

Environ Sci Pollut Res

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The quantitative assessment of landfill gas emissions is essential to assess the performance of the landfill cover and gas collection system. The relative error of the measured surface emission of landfill gas may be induced by the static flux chamber technique. This study aims to quantify effects of the size of the chamber, the insertion depth, pressure differential on the relative errors by using an integrated approach of in situ tests, and numerical modeling. A field experiment study of landfill gas emission is conducted by using a static chamber at one landfill site in Xi’an, Northwest China. Additionally, a two-dimensional axisymmetric numerical model for multi-component gas transport in the soil and the static chamber is developed based on the dusty-gas model (DGM). The proposed model is validated by the field data obtained in this study and a set of experimental data in the literature. The results show that DGM model has a better capacity to predict gas transport under a wider range of permeability compared to Blanc’s method. This is due to the fact that DGM model can explain the interaction among gases (e.g., CH4, CO2, O2, and N2) and the Knudsen diffusion process while these mechanisms are not included in Blanc’s model. Increasing the size and the insertion depth of static chambers can reduce the relative error for the flux of CH4 and CO2. For example, increasing the height of chambers from 0.55 to 1.1 m can decrease relative errors of CH4 and CO2 flux by 17% and 18%, respectively. Moreover, we find that gas emission fluxes for the case with positive pressure differential (∆Pin-out) are greater than that of the case without considering pressure fluctuations. The Monte Carlo method was adopted to carry out the statistical analysis for quantifying the range of relative errors. The agreement of the measured field data and predicted results demonstrated that the proposed model has the capacity to quantify the emission of landfill gas from the landfill cover systems.

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“…This land ll has been in operation since 1994 and covers an area of 730,000 m 2 . The capacity of the land ll is 49 million m 3 (Shen et al, 2018;Wang et al, 2020;Dang et al, 2020). A layer of loess with 30 cm is used for the temporary land ll cover.…”

Section: Land Ll Descriptionmentioning

confidence: 99%

Field investigation and numerical modelling of gas extraction in a heterogeneous landfill with high leachate level

Xie

Fei

et al. 2022

Environ Sci Pollut Res

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A eld gas extraction experiment is carried out at a high-kitchen food large-scale land ll site with high leachate level. The leachate level was decreased to improve the gas extraction e ciency. Considering the heterogeneity of the municipal solid waste (MSW), the voids in the unsaturated MSW are divided into matrix pores and fractures. A transient dual-porosity model was then developed to analyze the pumping test results. The rst and second boundary conditions considering the effect of cover layers of land lls was involved. The results show that the gas ow rate can be increased by 14%-25% due to the drawdown of the leachate level. Compared with the single pore model, the dual-porosity model can better predict the eld results, indicating that the preferential ow in the land ll caused by the heterogeneity of MSWs is very important. As the pumping pressure increases by 5 times, the ratio of fractures to pores w f can be decreased by 4.4 times. This may be due to the fact that the fractures will be compressed when the effective stress was increased as the negative pumping pressure was applied. The pumping pressure and the anisotropy value of the MSWs have the greater in uence on the well radius of in uence. The proposed model can be used for effective design of the eld gas pumping experiments. The obtained gas generation rate, gas permeability of the dual porosity MSWs can be useful for gas transport analysis and gas pumping well design for the high-kitchen food content land lls.

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Investigation of methane fluxes from temporary cover of Xi’an Jiangcungou landfill, China

Cited by 7 publications

References 55 publications

Effects of In-Situ Drying–Wetting Cycles on the Stress-Dependent Water Retention Behavior of Intact Loess

Effects of In-Situ Drying–Wetting Cycles on the Stress-Dependent Water Retention Behavior of Intact Loess

Numerical model for static chamber measurement of multi-component landfill gas emissions and its application

Field investigation and numerical modelling of gas extraction in a heterogeneous landfill with high leachate level

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