The controlling of landfill leachate evapotranspiration from soil–plant systems with willow: Salix amygdalina L

Abstract

The use of willows ( Salix amygdalina L) to manage landfill leachate disposal is an effective and cost-effective method due to the high transpiration ability of the willow plants. A 2-year lysimetric experiment was performed to determine an optimum leachate hydraulic loading rate to achieve high evapotranspiration but exert no harmful influence on the plants. The evapotranspiration rate of a soil–plant system planted with the willow was 1.28–5.12-fold higher than the rate measured on a soil surface lacking vegetation, suggesting that soil– willow systems with high volatilization rates are a viable landfill leachate treatment method. Of the soil–willow systems, the one with willow growing on sand amended with sewage sludge soil at an hydraulic loading rate of 1 mm day-1 performed best, with evapotranspiration ranging from 2.25 to 3.02 mm day-1 and a biomass yield of 8.0–9.85 Mg dry matter ha-1. The organic fraction of the soil increased as much as 2.5% of dry matter, due to the sewage sludge input, which exerted a positive effect on the biomass yield as well as on transpiration and evaporation. It was observed that the plants in the sand-and-sewage sludge soil systems displayed higher resistance to toxic effects from the applied landfill leachate relative to plants in the sand–soil systems.