BIODEGRADATION PHENOMENA DURING SOIL VAPOR EXTRACTION .3. SENSITIVITYSTUDIES FOR 2 SUBSTRATES

In the bioventing technique, soil vapor extraction (SVE) is used to pr omote aerobic biodegradation of contaminants in the vadose zone. Kinet ics limited by mass transport of the contaminant and/or oxygen through the aqueous phase to the microorganisms and of contaminant to the gas eous phase may be expected during field operation. Sensitivity studies were performed with a one-dimension model for two substrates showing competitive inhibition, following Monod's kinetics. The mass transfer limitations were represented by means of lumped parameters, and result s for high and low values of these parameters were compared. Under kin etics severely limited by mass transport processes, biodegradation occ urs at a rate given by the availability of dissolved oxygen, and impor tant contributions of biological degradation to the overall cleanup ar e expected if oxygen is not utilized exclusively for the oxidation of other substances than the target contaminant. For relatively fast mass transport kinetics the system becomes quite sensitive to a rather lar ge number of parameters, but important reductions in the remediation t ime will usually occur if high removal percentages are mandated.