SIMPLE METHOD FOR DETERMINING BREAKTHROUGH TIME OF ANTI-SEEPAGE LINERS IN LANDFILL

Abstract

A method for determining breakthrough time of anti-seepage liners in a landfill, includes (a) detecting a leachate sample of the landfill to determine the initial concentration C.sub.0 of pollutants, and monitoring the leachate head h of the landfill; (b) determining the pollution-causing concentration C.sub.A of the pollutants according to functional orientation of local groundwater of the landfill; (c) determining, related parameters of the anti-seepage liners including the thickness z of the anti-seepage liners, the permeability coefficient k of the liners, and the porosity n of the material of the liners, and determining the related parameters of pollutant migration including the effective diffusion coefficient D.sub.a* and the mechanical dispersion coefficient D.sub.m of the pollutants in the anti-seepage liners, and the adsorption retardation factor R.sub.d of the anti-seepage liners on the pollutants; and (d) calculating the breakthrough time t of the anti-seepage liners according to a formula,

[00001]$t=\frac{{\mathrm{nR}}_d.Math.z^2}{\left(h+z\right).Math.k}.Math.\left(\left({a?\left(\frac{C_0}{C_A}\right)}^b\right).Math.\ln ?\left(\frac{\left(h+z\right).Math.k}{n?\left(D_a^{*}+D_m\right)}\right)+c\right).$

Claims

1. A method for determining breakthrough time of anti-seepage liners in a landfill, comprising the following steps: (a) detecting a leachate sample of the landfill to determine an initial concentration C.sub.0 of typical pollutants, and monitoring a leachate head of the landfill; (b) determining a harm-causing or pollution-causing concentration C.sub.A of the pollutants according to a functional orientation of local groundwater of the landfill; (c) determining related parameters of the anti-seepage liners and related parameters of pollutant migration, the related parameters of the anti-seepage liners comprising the thickness z of the anti-seepage liners, a permeability coefficient k of the anti-seepage liners, and a porosity n of a material of the anti-seepage liners; and the related parameters of pollutant migration comprising an effective diffusion coefficient D.sub.a* and a mechanical dispersion coefficient D.sub.m of the pollutants in the anti-seepage liners, and an adsorption retardation factor R.sub.d of the anti-seepage liners on the pollutants; and (d) calculating the breakthrough time t of the anti-seepage liners according to a formula $t=\frac{{\mathrm{nR}}_d.Math.z^2}{\left(h+z\right).Math.k}.Math.\left(\left({a?\left(\frac{C_0}{C_A}\right)}^b\right).Math.\ln ?\left(\frac{\left(h+z\right).Math.k}{n?\left(D_a^{*}+D_m\right)}\right)+c\right),$ where a, b, c are state coefficients independently.

2. The method for determining breakthrough time of anti-seepage liners in a landfill according to claim 1, wherein in the step (a), the initial concentration C.sub.0 of the typical pollutants is detected according to the Chinese National Standard GB 5750-2006: Standard examination methods for drinking water

3. The method for determining breakthrough time of anti-seepage liners in a landfill according to claim 1, wherein in the step (a), the leachate head h of the landfill is monitored according to the Chinese Industry Standard CJJ 176-2012: Technical code for geotechnical engineering of municipal solid waste sanitary landfill.

4. The method for determining breakthrough time of anti-seepage liners in a landfill according to claim 1, wherein in the step (b), the harm-causing or pollution-causing concentration C.sub.A of the pollutants is the limiting concentration of the pollutants in different quality classifications that are specified in GB/T 14848-93: Quality standard for ground water or GB 3838-2002: Environmental quality standards for surface water.

5. The method for determining breakthrough time of anti-seepage liners in a landfill according to claim 1, wherein a is 0.2899, b is ?0.1343, and c is ?0.01094.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0017] FIG. 1 is a comparison diagram of breakthrough time of anti-seepage liners in a landfill according to the present invention against calculated values obtained by using an analytical solution; and

[0018] FIG. 2 is a comparison diagram of breakthrough time of 2-m compacted clay anti-seepage liners according to the present invention against finite-element calculated values.

DETAILED DESCRIPTION

[0019] Preferred embodiments of the present invention are described in detail below.

[0020] A simple method for determining breakthrough time of anti-seepage liners in a landfill provided by the present invention includes the following steps:

[0021] (a) detecting a leachate sample of the landfill to determine the initial concentration C.sub.0 (mg/L) of typical pollutants, and monitoring the leachate head h (m) of the landfill, where the initial concentration C.sub.0 of the typical pollutants is detected according to the Chinese National Standard GB 5750-2006: Standard examination methods for drinking water; the leachate head h of the landfill is monitored according to the Chinese Industry Standard CJJ 176-2012: Technical code for geotechnical engineering of municipal solid waste sanitary landfill;

[0022] (b) determining the harm-causing or pollution-causing concentration C.sub.A (mg/L) of the pollutants according to functional orientation of local groundwater of the landfill, where the harm-causing or pollution-causing concentration C.sub.A of the pollutants is the limiting concentration of the pollutants in different quality classifications that are specified in GB/T 14848-93: Quality standard for ground water or GB 3838-2002: Environmental quality standards for surface water;

[0023] (c) determining, through researches, related parameters of the anti-seepage liners and related parameters of pollutant migration, the related parameters of the anti-seepage liners including the thickness z (m) of the anti-seepage liners, the permeability coefficient k (m/s) of the liners, and the porosity n (?) of the material of the liners; and the related parameters of pollutant migration including the effective diffusion coefficient D.sub.a* (m.sup.2/s) and the mechanical dispersion coefficient D.sub.m (m.sup.2/s) of the pollutants in the anti-seepage liners, and the adsorption retardation factor R.sub.d (?) of the anti-seepage liners on the pollutants; and

[0024] (d) calculating the breakthrough time t of the anti-seepage liners according to a formula (1):

[00003]$\begin{array}{cc}t=\frac{{\mathrm{nR}}_d.Math.z^2}{\left(h+z\right).Math.k}.Math.\left(\left({a?\left(\frac{C_0}{C_A}\right)}^b\right).Math.\ln ?\left(\frac{\left(h+z\right).Math.k}{n?\left(D_a^{*}+D_m\right)}\right)+c\right),& \left(1\right)\end{array}$

[0025] where a, b, c are state coefficients independently, a is 0.2899, b is ?0.1343, and c is ?0.01094.

[0026] For points in FIG. 1, x-coordinates represent breakthrough time of anti-seepage liners in different working conditions that is obtained by using a conventional analytical solution, and y-coordinates represent breakthrough time of anti-seepage liners in corresponding working conditions that is calculated by using the formula (1). The points are basically close to the line y=x, and the correlation coefficient R.sup.2 of a fitting formula reaches 0.997, which indicates that the calculation accuracy of the formula (1) is still very high.

[0027] In addition, taking 2-m compacted clay anti-seepage liners that are commonly used in a landfill for example, the breakthrough time of organic matters (COD) in different leachate head conditions that is calculated by using the present invention is compared with the breakthrough time obtained by finite-element calculation.

TABLE-US-00001 TABLE 1 Parameters related to compacted clay anti-seepage liners in a landfill and parameters related to pollutant migration Leachate head h (m) 0.3 2 5 8 10 The thickness z (m) of liners 2 The permeability coefficient k (m/s) 1 ? 10.sup.?9 of liners Porosity (?) 0.54 Pollutants COD Diffusion coefficient D.sub.a* (m.sup.2/s) 2.5 ? 10.sup.?10 Dispersity ? (m) * 0.1 Retardation factor (?) 3.3 * Note: the dispersity ? is used to calculate the dispersion coefficient D.sub.m (m.sup.2/s): [00004]$\begin{array}{cc}{D}_m=?.Math.v_A=\frac{\left(h+z\right).Math.k.Math..Math.?}{\mathrm{nz}},& \left(2\right)\end{array}$where v.sub.A is average velocity (m/s).

[0028] For points in FIG. 2, horizontal coordinates represent leachate heads, vertical coordinates represent breakthrough time of 2-m compacted clay liners, the breakthrough time calculated by using a finite-element method is marked with solid dots, and the breakthrough time in corresponding working conditions that is calculated by using the formula (1) is marked with solid triangles. It is found by comparison that, the results of the two calculation methods are very close, which also indicates that the calculation accuracy of the formula (1) is very high.

[0029] The above embodiment merely illustrates the technical idea and features of the present invention, aiming to make persons skilled in the art learn about the content of the present invention and implement the present invention accordingly, and is not intended to limit the protection scope of the present invention. Any equivalent variations or modifications made based on the spirit of the present invention shall fall within the protection scope of the present invention.