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

Abstract

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.

Cell-free metabolic engineering enables selective biotransformation of fatty acids to value-added chemicals

“…The main compositions of food waste are carbohydrates, proteins, and lipids/oils; their proper disposal and/or recycling play an important role in global sustainable development ( Paritosh et al, 2017 ). Traditional solutions for the municipal waste treatment include landfilling and incineration, easily leading to seriously environmental issues such as air/soil pollution, greenhouse gas emission, and heavy metal leakage ( Hassan et al, 2020 ; Powell et al, 2016 ; Zhang et al, 2021 ). The use of food waste disposal units can decrease the amount of food waste; however, this method will aggravate the burden of water consumption and sewerage systems ( Iacovidou et al, 2012 ).…”

Analytical Solution for One-Dimensional Gas Pressure Distribution Considering the Variation of Gas Permeability Coefficients with Burial Depth

“…The model analyzed the effects of the gas generation rate, intrinsic permeability coefficient, intermediate cover layer, high-permeability horizontal permeable layer, and landfill gas drainage channel on the gas pressure distribution. Analytical solutions for the gas migration process through layered MSWs have also been proposed in Zeng [27], Zhang et al [28], and Wu et al [29].…”