Barrier materials for insulation of contaminated sediment

Summary

River sediment is frequently heavily loaded with pollutants. Even though particularly the estuary regions of large rivers are affected, no effective management strategy exists to date. The presently employed decontamination method (chemical extraction/biological reduction of pollutants) is rarely expedient due to the sedimet-specific heterogeneity of the pollutant mixes. Large-scale removal and storage is costly and the accumulated excavation matter needs to be handled in accordance with waste and soil conservation legislation.

The project's aim was therefore to develop reactive, permeable barriers capable of effectively insulating contaminated sediment and excavation matter as well as other mass waste, e.g. colliery waste, from its environs. The sub-project was concerned specifically with the identification of suitable materials for such barriers and the characterisation of these in regard to their applicability. Further, a reactive sediment cover was implemented in a model system under field conditions and facilities for long-term monitoring of pollutant propagation were developed.

Results:

• Zeolite minerals display good heavy metal retention through cation exchange, a good specific density (> 1), chemical stability in water bodies, no natural contamination and are available at low cost throughout the world.
• Cation antagonism at higher ionic strengths can dramatically reduce heavy metal retention capacity.
• Organic ligands result in a masking of heavy metals. Here, the slow decomplexation kinetics can drastically reduce retention.
• The mineral colloids transported in the pore water can contribute to pollutant transport.
• The monitoring concept established for long-term monitoring of active barrier systems is workable under field conditions. It is suitable for monitoring dissolution over time and over area and is resistant to long-term biological and chemical effects.

Project Participants

Implementing Institutions

Technische Universität Hamburg-Harburg - Institut für Umwelttechnik und Energiewirtschaft

Promotion

Promoting Institutions

Federal Ministry of Education and Research (BMBF)

More Project Information

Project title: Anwendung von aktiven Barriere-Systemen zur Minimierung der Schadstoff-Freisetzung aus kontaminierten Meeres- und Süßwassersedimenten - Teilvorhaben B: Auswahl und Prüfung von Materialien für die "aktive Barriere" (ABS)

Project number: 02WS9732/4

Project period: 1996 - 2002

Project region: Germany (Hamburg), Australia

Project contact:

Herr Prof. Dr. Förstner