Behaviour of heavy metals in soil beneath a landfill; Results of model experiments

Column experiments were set up in order to study the behaviour of heavy metals from landfill leachate in the soil. Special attention was given to the influence of fatty acids in the leachate on the mobility of lead, copper, nickel and zinc. In addition the influence of the kind of soil material was investigated. Of the six columns used in the experiments, three were percolated with synthetic landfill leachate and three with the same leachate without fatty acids. In both cases the three columns contained sand, sand mixed with fine clay particles and sand mixed with large clay aggregates. All experiments were carried out under anaerobic conditions. The soil solution of each column was periodically analysed. At the end of the experiments, after 7 months, the soil was analysed for precipitates and adsorption of metals. In the presence of fatty acids, breakthrough of respectively nickel, zinc and lead took place, whereas copper accumulated in the soil. In the absence of fatty acids precipitation and adsorption of the metals took place.