Change of isoprenoids, steranes and terpanes during ex situ bioremediation of mazut on the industrial scale

Abstract

This paper presents the results of an ex situ bioremediation of soil contaminated by mazut (heavy residual fuel oil) in the field scale (600 m 3. The treatment-bed (thickness 0.4 m) consisted of mechanically mixed mazut-contaminated soil, softwood sawdust as an additional carbon source and crude river sand, as a bulking and porosity increasing material. The inoculation/rein- oculation was conducted periodically using a biomass of a consortium of zy- mogenous microorganisms isolated from a bioremediation substrate. The bio- stimulation was performed through addition of nutritious substances (N, P and K). The aeration was improved by systematic mixing of the bioremediation system. After 50 days, the number of hydrocarbon degraders had increased a 100 fold. Based on the changes in the group composition, the average biode- gradation rate during bioremediation was 24 mg kg-1 day -1 for the aliphatic fraction, 6 mg kg-1 day-1 for the aromatic fraction and 3 mg kg-1 day-1 for the nitrogen-sulphur- oxygen compounds (NSO)-asphaltene fraction. In the saturated hydrocarbon fraction, gas chromatography-mass spectrometry (GC-MS) in the single ion-monitoring mode (SIM) was applied to analyse isoprenoids pristane and phytane and polycyclic molecules of sterane and triterpane type. Biodegradation occurred during the bioremediation process, as well as a reduction of the relative quantities of isoprenoids, steranes, tri- and tetracyclic terpanes and pentacyclic terpanes of the hopane type. 2010 Copyright (CC) SCS.