Analytical solution for one‐dimensional steady‐state contaminant transport through a geomembrane layer (GMBL)/compacted clay layer (CCL)/attenuation layer (AL) composite liner considering consolidation

Abstract

A composite liner system consisting of a geomembrane layer (GMBL), a compacted clay layer (CCL) and an attenuation layer (AL) is widely used in the modern landfills. The field and experimental observations highlight the potential detrimental effects on breakthrough of contaminants induced by consolidation of soil liner when a relatively high applied stress is caused by the waste placement. A one dimensional steady‐state model is developed to investigate the behaviour of contaminant transport in GMBL/CCL/AL composite liner system considering consolidation. Effects of the consolidation process on the transport of typical contaminants are investigated by the proposed analytical solution. The analytical results show that the magnitude of volume compressibility coefficient in the AL is important in controlling the overall magnitude of the consolidation induced effects. The process of consolidation shows a larger impact on the absorbable pollutants compared to the non‐absorbable pollutants. This may be due to the fact that the migration of solid particles induced by the consolidation may assist the transport of contaminant absorbed on them. The thickness of the AL shows large impacts on the bottom flux for the case with a high volume compressible coefficient. Increasing the thickness of AL from 1 to 3 m can results in a factor of 2.6 increase of the bottom flux. Increasing the thickness of the AL leads to a larger consolidation advection and a longer consolidation path, which may be the dominant mechanisms for contaminant transport compared to the diffusion process.

Review of the Anti-Pollution Performance of Triple-Layer GM/GCL/AL Composite Liners

“…When the GM is exposed to solar radiation during installation, it bends upward to form wrinkles [ 23 , 24 , 25 , 26 , 27 , 28 ]. Because of the large number of wrinkles on GM (the coverage rate of wrinkles can reach 30% or even higher) and most of them being hydraulically connected, the defects most likely combine with them [ 29 , 30 , 31 , 32 , 33 , 34 ]. To calculate the leakage rate of the hole combined with the wrinkle ( Figure 4 ), the length of the wrinkle is assumed to be significantly greater than its width, and that the leachate first moves laterally in the transfer layer, beyond the boundary of the wrinkle to a wetting radius, after which it moves longitudinally in the underlying soil layer.…”

Analytical solutions for chemical dissolution‐front instability problems involving radially divergent flow within fluid‐saturated porous media

“…[29][30][31][32] Even if they rely on some necessary assumptions that might not be valid in a specific application, such analytical solutions are widely adopted as a basic benchmark test tool for dealing with other specific mass transport problems in porous media. [33][34][35][36] If the chemical dissolution process is neglected, [37][38][39][40] then it is much easier to derive analytical solutions for mass transport problems than for CDFI problems, because the first-order perturbation equations of the system are not established and solved in the previous studies. [37][38][39][40] This means that only the analytical base solutions were derived for mass transport problems in the previous studies, [29][30][31][32][33][34][35][36][37][38][39][40] from the linear stability point of view.…”

“…[33][34][35][36] If the chemical dissolution process is neglected, [37][38][39][40] then it is much easier to derive analytical solutions for mass transport problems than for CDFI problems, because the first-order perturbation equations of the system are not established and solved in the previous studies. [37][38][39][40] This means that only the analytical base solutions were derived for mass transport problems in the previous studies, [29][30][31][32][33][34][35][36][37][38][39][40] from the linear stability point of view. 7,8,12 From the mathematical point of view, deriving analytical solutions for initially planar CDF propagating problems in fluid-saturated porous media, which is labeled the former case, is also much easier than deriving analytical solutions for initially circular CDF propagating problems in the same fluid-saturated porous media, which is labeled the latter case.…”

“…If the chemical dissolution process is neglected, 37–40 then it is much easier to derive analytical solutions for mass transport problems than for CDFI problems, because the first‐order perturbation equations of the system are not established and solved in the previous studies 37–40 . This means that only the analytical base solutions were derived for mass transport problems in the previous studies, 29–40 from the linear stability point of view 7,8,12 …”

Analytical solutions for a fully coupled hydraulic‐mechanical‐chemical model with non‐zero initial concentration of contaminant

“…In recent years, numerous studies have focused on deriving analytical solutions for contaminant transport models expressed by advection‐dispersion equations (ADEs), including the classical one‐dimensional ADE considering factors such as adsorption and/or decaying contaminant sources, 16–21 as well as two‐dimensional or three‐dimensional problems 22–24 . Furthermore, analytical solutions have also been developed for composite clay liners 25–45 and multicomponent contaminants 46–61 . Subsequently, research on analytical solutions that considered partial‐coupled HMC effect has been conducted 62–66 .…”