Detecting Landfill Leachate Contamination Using Soil Electrical Properties

Abstract

The use of complex permittivity and electrical conductivity to detect soil contamination by landfill leachate is discussed in this paper. The electrical conductivity and complex permittivity of a natural clayey soil are measured before and after permeation with multiple aqueous ionic solutions (synthetic leachate) that simulate the composition of leachate from a domestic solid waste disposal facility, and with aqueous CaCl2 solutions at various concentrations. The dielectric and electrical characteristics of soil, the experimental apparatus and procedure, and the analysis methodology are discussed, followed by the results of complex permittivity measurement before and after permeation using the synthetic leachate and CaCl2 solutions at various concentrations. The results show that the experimental system provides reliable measurement of the soil complex permittivity at 250 MHz and of the soil static electrical conductivity. The relative permittivity of soil is shown to decrease linearly with the overall cationic concentrations in the pore fluid, whereas the relative loss factor and electrical conductivity of soil increases linearly with the overall cationic concentration in the soil pore fluid. The cationic species can be distinguished in terms of the different linear regression trend lines of the electrical conductivity, relative permittivity, and loss factor versus ionic concentrations.