Biological remediation of contaminated sites: development of microbiological/adsorptive methods for in-situ decontamination

For in situ and on site treatment of PAH contaminated soils biotechnological methods were developed and applied. Several reactor types for biotreatment of contaminated soil were tested in order to estimate an optimum degree of PAH removal from different types of soil. For the treatment of silty soils a hydraulic fluidized bed reactor proved to be most suitable.

The object of this project was the development of microbiological processes for the in-situ and on-site treatment of contaminated soils with a hard coal content, together with test processes which can be used as a basis for the evaluation of the potential success and costs of biological decontamination.

The following tasks have been undertaken:

• Selection of two appropriate sites and characteristic definition of soil samples,
  
  
• Development and testing of microbiological decontamination methods,
  
  
• Establishment of a clean-up strategy for soils contaminated with polycyclic aromatic hydrocarbons (PAHs).

Results:

• The geological, chemical and microbiological characteristics of the sites of two former coking plants have been established.  Using soil samples from these and other sites, investigations into the kinetic behaviour, degradation rates and degradability of PAHs by micro-organisms have been conducted.
  
  
• The resulting test indicating scope for decontamination delivers reliable forecasts on the rate and extent of microbial PAH degradation in soil samples.  For the ecotoxicological evaluation of soils, biological tests have been developed and optimised for application to the soil medium.
  
  
• On many sites, the high superfine particle content of soils is a significant factor, since only reactor processes are suitable for the treatment of these soils.  To this end, a circulating fluidised bed process has been developed, optimised and tested on a pilot plant scale.  This process operates with a high solids content (50%) in the biological stage, and is distinguished by limited dwell times and the low energy input required for the maintenance of the suspension.

Source Of Supply: The final report (call number F 95 B 898, in German) can be borrowed from:
Technische Informationsbibliothek (TIB) Hannover
Welfengarten 1B
30167 Hannover





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