Transfer of Phenolic Compounds Through Landfill Bottom Liners

Abstract

Landfills contain toxic micropollutants such as phenolic compounds, which are toxic to humans and the environment even at very low concentrations. This paper presents a study of how the design of composite liners as per French and European regulations and the distribution of defects in the geomembrane affect the transfer through the liners of bisphenol A (BPA), pentachlorophenol, 2,4-dichlorophenol, and 2,4,6-trichlorophenol. Results obtained from numerical modeling show that, depending on the pollutant involved, the composite liner studied, and the micropollutant half-lives in waste and in soil, the peak concentration of micropollutants in the surrounding aquifer can exceed acceptable levels and thereby impact public health. For BPA, none of the composite-liner configurations considered in the study ensure adequate protection of the aquifer. For lower pollutant concentrations, adequate protection is possible in some configurations for the other three micropollutants studied. Despite the calculation not accounting for sorption in the soil, the study emphasizes the important effects of attenuation-layer thickness and the calculation parameters. In all cases, equivalence is obtained by reinforcing a compacted clay liner of reduced thickness by a geosynthetic clay liner. The study emphasizes the need for additional data on the half-lives and proportion of micropollutants in waste, which may be obtained from studying the behavior of phenolic compounds under anaerobic conditions in waste and in soil.