Industrial-scale bioremediation of a hydrocarbon-contaminated aquifer’s sediment at the location of a heating plant, Belgrade, Serbia

The aim of this paper is to provide insight into research and activities of in situ remediation to remove petroleum hydrocarbon pollutants from a contaminated aquifer’s sediment, located near two radial collector wells of a water supply system. It was decided that the most appropriate method for remediation of this aquifer’s sediment is in situ bioremediation because it is clean, efficient and sustainable technology. Before the start of the bioremediation process, it was necessary to isolate and cultivate the microorganisms present at the contamination site, so they could be later applied in the bioremediation process. The samples before and after the bioremediation were studied using both GC and GC × GC–MS to determine how the concentrations of contaminants changed over time. Additionally, in this paper, a spatiotemporal representation of the change in hydrocarbon content by depth within the zone of the highest contamination over time is shown. After 12 months of bioremediation, the hydrocarbon content in the samples decreased by 82.0%, and based on GCxGC-MS analysis, the order of degradation of various hydrocarbon groups was as follows: steranes (99.6%), isoprenoids (98.4%), benzene derivatives (98.4%), alkanes (97.2%), and terpenes (49.3%). The exponential decay model showed the greatest decomposition rate of hydrocarbons occurred at depths of 8–10 m, with an average decay constant of 0.227, independent of the initial concentration of hydrocarbons. To the best of our knowledge, to date, the described approach has not been applied to an aquifer (the simultaneous treatment of groundwater and its associated sediment layers).