Transient analytical solution for one-dimensional transport of organic contaminants through GM/GCL/SL composite liner

Feng, Shi‐Jin; Peng, Ming-Qing; Chen, Zhang‐Long; Chen, Hongxin

doi:10.1016/j.scitotenv.2018.08.413

Cited by 44 publications

(36 citation statements)

References 46 publications

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“…The physical properties incorporate diffusion, advection, and dispersion 15 – 16 . The chemical process includes sorption, dissolution, complexation, hydrolysis/substitution and oxidation 17 – 19 . To predict the leaching of chlorides, zinc, iron, lead, and copper numerical parameters engaged with governing set of equations that depict the model processes should be accurately characterized.…”

Section: Methodsmentioning

confidence: 99%

“…The one-dimensional vertical flow is numerically represented by the accompanying partial differential equation as expressed below and is the governing equation (Eq. 1 ) 15 , 19 . C t indicates the concentration corresponding to time, D h is the hydrodynamic dispersion coefficient, v represents the seepage velocity, represents the volumetric water content, R indicates the retardation factor of the fly ash–bentonite layer (can be determined by the following the procedures given by Chen et al 16 ; Xie et al 19 ) and can be determined by Eq.…”

Section: Methodsmentioning

confidence: 99%

“…The initial condition of the liner system can then be expressed as (Chen et al 16 ; Xie et al 9 ; Feng et al 18 , 19 ): …”

Section: Methodsmentioning

confidence: 99%

“…The thickness of the liner is an essential deciding factor since it determines the strength and permeability. Till date, many researchers studied the use of analytical 15 – 19 and numerical approaches 20 for contamination transport (mainly organic) and to determine the liner thickness. However, the analytical methods are timing consuming and difficult for solving non-linear and differential equations 20 .…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Modelling contaminant transport in fly ash–bentonite composite landfill liner: mechanism of different types of ions

Garg

Reddy

Huang

et al. 2020

Sci Rep

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Generated hazardous or toxic waste posses a serious threat if dumped into ponds or low lying areas which leads to contamination, this necessitates the effective landfill liner system. Mainly compacted clayey soils are used as an engineered barrier. Recently, composite materials have gained popularity as landfill liner materials, including the use of waste materials amended with low permeable soils. Though, studies on the composite optimum mix and its corresponding thickness are very scarce. Here, we evaluated the unconfined compressive strength and hydraulic conductivity of fly ash-bentonite composites. Efforts were also made to determine the thickness of landfill liner composite using a finite difference method (i.e. MATLAB). The results reveal that composite consists of 30% bentonite and 70% fly ash is suitable for landfill liner, which meets strength and permeability criteria. Numerical simulation for five major contaminants shows that the composite plays a crucial role in reducing the leaching of heavy metals and suggests an optimum thickness in the range of 126-154 cm. Overall, the findings of the study indicate that fly ash-bentonite composite can be used to solve real-life challenges in a sustainable way. Landfill liner is a low-permeable barrier, which acts as a partition between the waste and its surrounding environment. Well constructed landfills are more secure than open dumping 1. The fundamental factor influencing the nature of compacted clay liners is their low permeabilities, which should be as less as 1.0 × 10-7 cm/s suggested by RCRA (Subtitle D). To avoid contamination of groundwater (due to permeation of leachate), generally clayey soils are compacted to achieve desired permeability. Sand-bentonite composites are also used as engineered barriers or liners to prevent leaching of contaminants 2. Other than hydraulic conductivity, strength also needs to be considered in assessing landfill liner material. Earlier studies and environmental guidelines proposed a minimum unconfined compressive strength (UCS) of 0.20 MPa to utilize as a landfill liner material 3. Few studies reported that waste-bentonite composites satisfy the strength criteria when a correct mix proportion used 3,4. The utilization of wastes like fly ash solves the problems associated with waste management and also saves the extensive exploitation of natural materials 5,6. Fly ash and bentonite can replace the sand-bentonite liners because of lack of available natural sand and an increase in the cost, which is widely used in other construction activities. Fly ash is known for its pozzolanic reactions, and that solidifies and gains strength over time when cured. Therefore, the curing period prompts an increase in strength and reduction of hydraulic conductivity. Recent studies have examined the amendment of fly ash to the soil, found the enhanced geotechnical properties such as cation exchange capacity, shear strength, and hydraulic conductivity 3,7,8. Problems in landfill lining system of a waste containment facilities can be escalate...

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

“…The initial condition of the liner system can then be expressed as (Chen et al 16 ; Xie et al 9 ; Feng et al 18 , 19 ): …”

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Modelling contaminant transport in fly ash–bentonite composite landfill liner: mechanism of different types of ions

Garg

Reddy

Huang

et al. 2020

Sci Rep

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“…Many studies have been performed on mathematical simulations of pollutant migration [8][9][10][11][12][13][14][15][16][17][18]. The effect of boundary conditions on the simulation results has been discussed through theoretical analysis [8][9][10].…”

Section: Introductionmentioning

confidence: 99%

Analysis of Factors for Compacted Clay Liner Performance Considering Isothermal Adsorption

2021

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The concentration profiles and breakthrough curves of the 2 m thick compacted clay liner (CCL) given in the specification were compared, considering three different adsorption isotherms (upper convex, linear, and lower concave). In addition, the effects of transport parameters, sorption isotherms, and source concentrations on pollutant migration were analyzed. The results showed that the dimensionless breakthrough curves of different source concentrations considering the linear adsorption isotherm coincided with each other, as the partition coefficient of the linear adsorption isotherm was constant. For the lower concave isotherm, the migration of a large source concentration was slowest, because the partition coefficient of the lower concave isotherm increased with an increase in concentration. For the upper convex isotherm, the migration of a large source concentration was fastest, because the partition coefficient decreased with an increase in concentration. The effects of the nonlinear isotherms on the shape of the outflow curve were similar to the effects of a change in the hydrodynamic dispersion (Dh): the concentration front of the upper convex isotherm was narrower, which was similar to the effect of a reduction in Dh (i.e., PL), and the concentration front of the lower concave isotherm was wider and similar to the effect of an increase Dh (i.e., PL). Therefore, the diffusion and adsorption parameters were fitted separately in the study, in case the nonlinear adsorption behavior was mistakenly defined as linear adsorption.

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Semi‐analytical solution for the two‐dimensional transport of organic contaminant through geomembrane with strip defects to the underlying soil liner

Sun

Peng

et al. 2022

Num Anal Meth Geomechanics

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Geosynthetic materials are widely adopted as part of barrier liners in landfills, while the existence of defects in geomembrane (GM) will significantly reduce the barrier efficiency and lead to unexpected pollution in the surrounding environment. In this study, a novel semi-analytical model was proposed to investigate the two-dimensional (2D) migration of organic contaminant through the GM with strip defects to the underlying soil liner (SL). This model has the superiority to consider the concentration condition in the defects, and describe more accurate concentration profiles in the SL. The combination of discretization method and integral transforms were applied to obtain semi-analytical solutions, which were then verified by numerical solutions. Results show that the existence of defects can substantially accelerate the migration process of contaminant through flawed GM to the underlying SL. Specifically, the time interval between migration curves in the model with defects can be 2 or 3 orders of magnitude shorter than that without defects under the same condition.

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Transient analytical solution for one-dimensional transport of organic contaminants through GM/GCL/SL composite liner

Cited by 44 publications

References 46 publications

Modelling contaminant transport in fly ash–bentonite composite landfill liner: mechanism of different types of ions

Modelling contaminant transport in fly ash–bentonite composite landfill liner: mechanism of different types of ions

Analysis of Factors for Compacted Clay Liner Performance Considering Isothermal Adsorption

Semi‐analytical solution for the two‐dimensional transport of organic contaminant through geomembrane with strip defects to the underlying soil liner

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