Biodegradation of hydrocarbons: microbiological degradation of residual oil fractions using fatty acid-modified amino acids – increase in bioavailability

The degradation of hydrocarbons in soils can be stimulated by the use of newly-developed surfactants. However, the reduction in the residual oil concentration achieved by this method is not sufficient for the thorough decontamination of soils. A combination of this method with other chemical and physical processes is therefore recommended.

A substantial number of industrial and military sites are contaminated by mineral oils which represent a hazard, both to persons and the environment.  In many cases, the microbiological decontamination processes which are frequently applied to polluted sites of this type will not allow compliance with statutory limiting values to be achieved.  In general, residues equivalent to 10 – 50% of the initial concentration will remain.  In combination with more effective mixing, surface-active agents are applied in an attempt to increase the bioavailability of pollutants.

The object of investigations conducted was the application of newly-developed surfactants from the fatty acid-acylated amino acid substance group.  It was intended to test the suitability of these surfactants for the acceleration of mineral oil degradation and the improvement of degradation performance.  To this end, degradation tests have been conducted on residual oil from a biostack in which the degradation process has stagnated, and on soil washing sludge.

Results:

• The addition of lauric acid-acylated aliphatic amino acids has improved the degradation of residual oil in the biostack by a further 50%, in comparison to operation without surfactants.
  
  
• By the addition of surfactants to soil washing sludges, it has been possible to reduce residual mineral oil concentrations by 10 – 15%.
  
  
• Since, in common with other chemical and physical processes, the application of surfactants alone will not allow satisfactory results to be achieved, the combined application of a number of processes represents a rational option.

Source Of Supply: The final report (call number F 99 B 797, in German) can be borrowed from:
Technische Informationsbibliothek (TIB) Hannover
Welfengarten 1B
30167 Hannover





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