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unilogo Universität Stuttgart
Institute of Hydraulic Engineering

Research: VEGAS - Research Facility for Subsurface Remediation

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Development of an immobilization technique for heavy metals by using the geogenic sulphate in groundwater
Project manager:Jürgen Braun, Ph.D.
Deputy:Dr.-Ing. Norbert Klaas, M.Sc.
Research assistants:Dr.-Ing. Sylvia Mackenberg
Duration:1.10.2005 - 31.12.2006
Funding:Baden-Württemberg-Programm Lebensgrundlage Umwelt und ihre Sicherung (BWPLUS)
Comments:

This project is part of the research area:
In-Situ Remediation Technologies

Publications: Link

Abstract:

Unlike organic contaminants there are only a few in-situ remediation techniques available for inorganic contaminants, in particular for heavy metals. Although the number of concerned sites is smaller, causes to the subject of protection created by heavy metals might be more serious.

The objective of the research activities carried out at VEGAS was to investigate the feasibility of a remediation technique to immobilize heavy metals by using the geogenic sulphate in the groundwater. The mechanism of action of this remediation technique is to permanently immobilize the mobile heavy metal components present in soil and groundwater as poorly water soluble metal sulfides or at least to limit the mobility of the heavy metal components to an extent that only ecotoxicologically irrelevant concentrations enter the cycle of matter. In the framework of the research project the heavy metal chromate was investigated. Though chromate does not form a sulfide, but it reacts to an immobile chrome(III)hydroxide under reductive conditions.

During field application the formation of metal sulfides will be achieved by using the geogenic sulphate content coupled with in anaerobic groundwater naturally occurring sulphate reduction. In the framework of this research project sodium sulphate was added to tap water to simulate sulphatic groundwater. To realize anaerobic conditions the applicability of molashine as an organic carbon source was investigated. The following heavy metals and metalloids were part of the studies: cadmium, lead, mercury, arsenic, zinc, barium, and chrome.