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unilogo Universität Stuttgart
Institute of Hydraulic Engineering

Research: VEGAS - Research Facility for Subsurface Remediation

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Investigations into the comparability of laboratory and lysimeter experiments for leachate prognosis
Project manager:Dr.-Ing. Norbert Klaas, M.Sc., Jürgen Braun, Ph.D.
Research assistants:Dr.-Ing. Sylvia Mackenberg
Duration:1.12.2004 - 31.12.2005
Funding:BMBF
Comments:

This project is part of the research area:
Behaviour of Contaminants in the Subsurface


Abstract:

The BBodSchV has established a method of estimating either the contaminated materials or the expected pollution amounts in the ground water via the leachate prognosis. The research differentiates between the terminology of source strength and pollutant transport. This particular research project focused on systematic column experiments to determine the source strength. The objective of the research was to analyse the impact of the contact time between the column eluate and the surrounding material, while focusing on potential correlations between laboratory and filed work – especially with respect to up-scaling from lab results to actual sites. Therefore, saturated column experiments with varying column dimensions and different flow rates as well as unsaturated column experiments with varying column dimensions were implemented. The column dimensions generally did not impact the eluate concentration in saturated experiments. The differing flow rates (i.e. very long contact times between eluate and the material in the columns) resulted in somewhat varying concentrations. When deviations occurred the eluate generally had a lower concentration. This is likely caused by biological reactions (carbonization, immobilization). The varying column dimensions of the unsaturated samples also only had a minimal impact on the eluate concentration. Some parameter show lower concentration when the column dimensions were increased (longer contact times). This can likely be attributed to the precipitation (CO2 contact with the atmosphere and biological reactions). Overall saturated column experiments tend to forecast somewhat higher concentrations of some parameters than in the actual unsaturated conditions. Generally the application of saturated column experiments can be recommended for the quality evaluation of most of the inorganic parameters. This approach continues to be problematic for the quality evaluation of the PAH. Realistic forecasts for an approximate correlation between laboratory and field work is only possible for unsaturated material with a high pH-value (such as construction debris) in which a biological degradation is not possible.