Effectiveness of Crude Biosurfactant Mixture for Enhanced Biodegradation of Hydrocarbon Contaminated Soil in Slurry Reactor

Abstract

A crude biosurfactant mixture was produced in a 1.4 L tubular reactor by a mixed culture; after<br />the thermal treatment of the whole culture an increase in emulsification activity and surface tension was<br />observed, with a main effect on the first one. The emulsification index of the mixture obtained was of 60.4 %. The crude mixed biosurfactant was used to enhance hydrocarbon biodegradation of intemperized soil in a<br />slurry reactor, for which two biodegradation assays were carried out. In the first reactor (R1), the crude mixed<br />biosurfactant was added along with inoculum at initial stage, and the second reactor (R2) was inoculated 5 days after the initial biosurfactant addition. When the crude biosurfactant mixture was added as a pretreatment (R2), the extent and rate of hydrocarbon biodegradation was increased efficiently in the slurry phase reactor 1.3-folds in comparison to non-biosurfactant control. So, the initial hydrocarbon content (9,275 g/kg of dry soil) was reduced to 674 ± 34 mg kg-1 with about 92% of removal efficiency at the 10 days of treatment in the slurry reactor. On the other hand, the bioreactor that received the biosurfactant and the inoculum at the initial stage showed slower hydrocarbon consumption and as result hydrocarbon content was reduced by approximately 34%.