Investigation of indicating pollutant for landfill leachate breaking through anti-seepage system

The leachate of the landfills in China consists of different pollutants and has complex composition. Breaking through anti-seepage system and contaminating the underground water and soil by pollutants have become the concern of environmental safety for landfills. However, the criteria of breakthrough and the indicating pollutant used to calculate the time of breakthrough and evaluate the performance of the anti-seepage system are not clear. To solve this problem, based on the concentration of average pollutants in six typical landfills in China and the limit concentrations for different pollutants in environmental standards, one-dimensional advection-dispersion finite element models are established. Compared with heavy metals and persistent organic pollutants (POPs), COD breaks through the anti-seepage system first, and it can be regarded as the indicating pollutant to determine the breakthrough time. The time of breaking through the single and double HDPE composite liners is 84.2 years and 122.6 years. The breakthrough time is influenced by the initial pollutant concentration, limit pollutant concentration and parameters of pollutant migration together. The results can be a reference for calculating the breakthrough time and evaluating the performance of the anti-seepage system.