General Cleanup Technology

Technical support trials and the modelling of flow and transport characteristics of cleanup technologies for inorganic pollutants in the underground environment

The use of permeable reaction walls represents a practicable alternative to the cleanup measures which have customarily been applied hitherto to arsenic-contaminated sites. Conversely, the in-situ immobilisation process using iron hydroxide, which has been tested in a pilot plant, has proved to be of only limited practicability. 

 

Summary

In the past, the use of arsenic compounds led to frequent instances of soil contamination.  The toxic and carcinogenic properties of arsenic are such that soils must be decontaminated where the limiting values for arsenic are exceeded.

As part of the overall project “Cleanup technologies for inorganic pollutants in the underground environment”, this project involved the preparation, technical support and evaluation of laboratory tests. The key focus of investigations was an in-situ immobilisation process, together with the use of reaction walls with iron hydroxide-Fe(OH)3-coarse sand and the Ratio®Pur adsorber resin.

Results:

  • The practicability of the in-situ immobilisation process based upon Fe(OH)3 in the field is limited.  Preconditions for the application of this process are oxidising conditions in the underground environment and a groundwater pH value of 6 – 9.
  • Chemicals are introduced into the underground environment using a circulation well system.  The high density of wells required to ensure the uniform distribution of Fe(OH)3 generates process costs of the order of € 250 per 100 kg of Fe(OH)3.
  • The strong remobilisation properties of arsenic are such that the use of Fe(OH)3-coarse sand reaction walls is not recommended in practice.  Reaction walls using the Ratio®Pur adsorber resin have proved to be suitable for the cleanup of groundwater pollution.  By increasing the wall thickness from 10 to 20 cm, it has been possible to immobilise over 95% of arsenates; remobilisation observed was low, and the stability of arsenic immobilisation was sufficient.

More Project Informations

Project title:  Cleanup technologies for inorganic pollutants in the underground environment: recovery of samples, technical support trials and the modelling of flow and transport characteristics

Project number:  0271089

Project period:  1998 - 2001

Project region:  Germany (Baden-Württemberg)

Project contact:

Herr Dr. Ertel

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