General Cleanup Technology

Self-cleaning potential of aquifers contaminated with explosive-typical compounds

Object of research are the natural sorption and reduction mechanisms of explosive-typical compounds in groundwater aquifers in Torgau/Elsnig. The results allow the assumption that complex contamination slows reduction of some explosive-typical compounds and that polar compounds display a lower capacity for self-reduction than non-polar compounds regardless solar irradiation.

Summary

Dissemination of anthropogenic organic substances in the environment particularly pollutes groundwater, which has to be purified by means of costly procedures. However, this purification can be supported by natural processes which can permanently convert a proportion of the pollutants into harmless substances (natural attenuation). But establishing whether these self-cleaning processes are sufficient to adequately minimise existing damage or whether additional decontamination measures need to be taken requires detailed, site-specific process analyses.
This project therefore researches sorption and reduction mechanisms for explosive-typical compounds as well as the effect the conditions within the aquifer have on these processes. To this end, laboratory experiments are conducted to identify the effect of geochemical boundary conditions on sorption and reduction of explosive-typical compounds and the results are verified by on-site field research.

Results:

  • Small amounts of residue were determined for all substances. This is caused by sorption on the small quantities of clay minerals. Sorption is determined by steric effects, the number of nitro functional groups and the aromaticity of the explosive-typical compounds.
  • For polar, multi-nitrified explosive-typical compounds, it was proven that some (RDX, 2,4,6-trinitrobenzoic acid, 2,4-dinitrobenzoic acid, 2,4-dinitrotoluolene-5 sulphonic acid and 2,4,6-trinitrophenol) can be converted under tertiary sediment conditions.
  • The research indicates that complex contamination may slow reduction of some explosive-typical compounds.
  • The examined polar explosive-typical compounds can be converted through sunlight but display slower reaction rates and a lower self-cleaning capacity than non-polar explosive-typical compounds.
  • The reduction constants of the explosive-typical compounds quantified through pillar tests were 0.01 d-1 to 0.6 d-1. The reduction constants determined through an analytical model lay within the range determined in the laboratory.

More Project Information

Project title: Verbundprojekt: KORA, Teil 5, Verbund: "Nutzung von Selbstreinigungspotentialen in STV-belasteten Böden und Grundwasserleitern" - TP 3: Überprüfung von Selbstreinigungspotentialen in STV kontaminierten Grundwasserleitern insbesondere unter Berücksichtigung von Milieubedingungen am Standortbeispiel Torgau/Elsnig

Project number: 0330509

Project period: 2002 - 2007

Project region: Germany (Saxony)

Project contact:

Frau Dr. Weber

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Source: German National Library of Science and Technology Hannover (TIB)