Erarbeitung mikrobiologischer Grundlagen für die Nachbehandlung von zuvor PAK-verunreinigten Böden nach der Dekontamination mit Hilfe einer Mikroemulsion sowie mikrobiologische Entsorgung der im Verfahrensprozess anfallenden schadstoffhaltigen Ölphase

The aim of this work was to determine whether a PAH-containing oil phase arising from a novel soil remediation process for PAH contaminated soil, in which extraction is performed with a microemulsion, could be eliminated microbiologically in a fermenter. In addition, the possibility of microbiological "polishing" of the extracted soil was investigated. Following extraction of the PAH contaminated soil with a microemulsion, a PAH-containing oil phase was produced which contained residual amounts of surfactant. It could be shown in a batch culture experiments that the PAH were degraded by a micobial mixed culture in the presence of the more easily degradable components of the microemulsion (rape oil, rape oil methylester, surfactant). In continuous culture experiments, it was found that almost complete degradation of the 5 PAH employed as a model contamination was achieved, although at high retention times rape oil methylester were also practically completely eIiminated. Using different ratios of oil, PAH and surfactant as well as varying the inflow concentration of the mixture showed that the concentration of oil influenced the degree of PAH degradation. Increasing the proportion of oil in the mixture increased the percentual PAH elimination. Decreasing the proportion of oil caused a limitation. Limitation of PAH degradation due to lower oil concentrations could be relieved by addition of biologicall undegradable solvent heptamethylnonane. Experiments on the biological remedeation of soil extracted with a microemulsion were carried out using a phenanthrene-contaminated orthic luvisol. Biological activity after extraction was measurable in the form of increased respiration and bacterial count which correlated with the elimination of the substances applied (phenanthrene, oil, surfactant). Addition of allochthonous microorganisms was not necessary. The presence of oil and surfactant retarded phenanthrene degradation due to substrate competition. The treated soil appeared not to have a toxic influence on the soil microflora