Permeability is a very important parameter to evaluate the landfill gas (LFG) transport properties of municipal solid waste (MSW). Waste permeability is largely dependent on pore structure, which is affected directly by compression stress and degradation. In this article, laboratory tests were conducted to determine the permeability of MSW under different stresses and degradation phases. Test results showed that porosity and permeability values were in the range of 0.11–0.65 and 8.7 × 10−14–7.29 × 10−12 m2, respectively. The porosity of waste samples declined exponentially with the increase of compacted density and linearly with the increase in water content. Permeability decreased significantly with stress and degradation because of the increase in compacted density and finer particles of the waste, which led to low porosity of the samples. The influence of stress on permeability was in the scope of 1.6 × 10−12–3.7 × 10−12 m2, whereas porosity was 0.23–0.34. However, the effect of coupled stress and degradation on permeability was reduced to more than an order of magnitude. The power model was found to be suitable for fresh and degradation wastes, whereas Kozeny–Carman model was only suitable for old wastes. This study provides theoretical and practical significance for environmental pollution control and resource utilization of LFG in landfills. © 2017 American Institute of Chemical Engineers Environ Prog, 36: 1694–1699, 2017

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The field-scale test of aeration to accelerate biodegradation of the waste was conducted, which was selected in an old landfill in Hubei province in China. The long-term monitoring was presented, lasted for 11 months, to estimate the degradation stability of the landfill. The monitoring parameters included the temperature, COD and BOD of leachate, gas concentration, water level, settlement, and cellulose/lignin. The results show that the waste degradation rate was increased under the aeration condition, while there was a trend of the stability in the whole waste body. The water level within the landfill was adjusted by discharge measurements, contributing to the buildup of the oxygen environment in landfill. The C/L could be used to assess the stability of the full-scale waste during the degradation process. But, there was obviously discrete by means of drilled sampling. The field-scale test was needed to provide the evidence for aeration engineering operation.

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The dual permeability model (DPM) is used to describe the gas flow in landfills under the preferential flow effect. A steady‐state radial DPM was developed in this study to predict gas distribution at extraction well operations. Two typical cases of a short‐term pumping field test from a single extraction well were also studied. The sensitivity of kf/km and mass transfer coefficient in the DPM was simulated. The mechanism of higher deviation between the simulation result and the test could be explained by the gas flux and influence radius, as determined by the single permeability model based on gas pressure distribution in the radial direction. The reliability of the DPM in the prediction of gas flux and influence radius in extraction wells was initially verified. The study provides evidence of the improvement of the design and operation parameters of extraction wells in landfills using the proposed method. © 2016 American Institute of Chemical Engineers Environ Prog, 35: 1381–1386, 2016