Transport fate of organic compounds with water through landfills

Hazardous organic compounds have previously been identified in landfill leachates. The emissions of the organic compounds with leachates from landfills are dependent, among other processes, on the water transport through the landfill and the sorption of the compounds to the waste. The purpose of this study was to examine the transport of organic compounds with percolating water through a pilot-scale landfill. The pilot-scale landfill was constructed at an actual landfill site and contained 540 m3 of ordinary household waste. Leachate collecting devices were placed at three levels. Lithium was used as a water tracer and was applied, together with specific organic compounds, at the top of the landfill. The waste was then irrigated with 10 mm of water per day, and leachate samples were collected and analyzed weekly. It was concluded that significant amounts of the water were percolating with preferential flow paths through the landfill, together with fractions of the organic compounds. It was also found that organic compounds transported in preferential flow paths were retained by sorption, but that the sorption did not reach equilibrium. It was suggested that preferential flow paths and organic compound sorption non-equilibrium should be taken into account when, for example, modelling landfill emissions. The results are applicable to the estimation of environmental risks from landfill leachates and for the evaluation of landfills as a treatment method for waste.