In-situ filter regeneration for the removal of TNT from groundwater: application of process to an activated carbon fibre adsorber

Summary

Activated carbon filters are generally used for the decontamination of trinitrotoluene (TNT) – polluted groundwater and leachate from abandoned armaments sites.  These filters are generally regenerated by thermal processes in centralised and large-scale installations.  This method generates both flue gas and CO2 emissions, and also necessitates extensive transport operations between the filtration installation and the regeneration installation.

As an alternative option, a forerunner to this project involved the development of a chemical regeneration process for in-situ application.  By this method, the desorption of pollutants from the activated carbon is achieved using caustic soda.  Hydrochloric acid is then used to restore the adsorbent properties of the activated carbon.

The present project was intended to investigate the extent to which results achieved using granulated activated carbon (GAC) as an adsorbent might be transposed to activated carbon fibre (ACF).

Results:

• In comparison with other adsorbent materials, ACF shows very high charging capacities, very rapid adsorption kinetics and effective levels of permeability.  In each specific case, these advantages must be set against the high price of ACF.
• The regeneration of ACF adsorbers uses comparable methods and generates wastewaters which are similar to those associated with GAC.  After the first regeneration, however, a substantial reduction has been recorded in the adsorption capacity of ACF, which has nevertheless been observed to stabilise in subsequent cycles.
• A software has been developed for purposes of process design and the setting of process parameters.

Project Participants

Implementing Institutions

TU Berlin, Department of Urban Water Management

Promotion

Promoting Institutions

Federal Ministry of Education and Research (BMBF)

More Project Information

Project title: In-situ filter regeneration for the removal of TNT from groundwater: application of process to an activated carbon fibre adsorber

Project number: 02WA0016

Project period: 2001 - 2002

Project region: Germany (Berlin)

Project contact:

Herr Prof. Dr.-Ing. Hegemann
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