GC/MS-SCAN to follow the fate of crude oil components in bioreactors set to remediate contaminated soil

In this paper GUMS-SCAN was used to identify the crude oil components that persist after bioremediation treatment of contaminated soil and the metabolites generated during this process. The soil was treated in bioreactors inoculated with an adapted bacterial population. In the first of two sets of conditions used, the water phase of the reactor was circulated continuously at a flow rate of 7 1 day], and in the other case, it was circulated for a short period once a day to give the equivalent of 0.5 l day(-1). Data showed that acyclic, n- and substituted alkanes greater than or equal to C-12 were still present after one year of remediation, while the majority of substituted derivatives of polycyclic and aromatic hydrocarbons could not be detected by GUMS-SCAN analysis. The number of components identified was about one-half of that initially observed. After treatment the same number of components was detected at the top and bottom of the reactor in which the water phase was circulated continuously, whereas a smaller number of metabolites were observed at the top rather than at the bottom of the reactor with discontinuous circulation. The analysis has pointed to the importance of n-alkanes, their substituted derivatives and polycyclic aromatic hydrocarbons as the most significant pollutants. (C) 2004 Elsevier Ltd. All rights reserved.