Biological upgrading of heavy oil cuts using native microbial consortia as an environmental-friendly technology in petroleum refineries

Refineries are amongst the most energy-intensive and polluting industries in the world. Biotechnology may serve as an alternative low-cost and environmental-friendly tool to the current costly, toxic and hazardous refining processes. In this study, the compositional redistribution of a heavy hydrocarbon cut is investigated under biological conversion using native microbial consortia. The native consortia were obtained by batch enrichment method applied on oil-polluted soil samples from oil refineries of Iran. The bioconversion experiments were conducted with 20% and 40% (v/v) of the heavy cut as the sole carbon source and 10% (v/v) of the consortia broth in 250 ml flasks containing a mineral medium. The samples kept at 30°C stirring at 120 rpm for one week. The biotreated hydrocarbons were then separated and analyzed for determination of saturate, aromatic and resin fractions using column chromatography and gravimetric measurements. The results showed that the amounts of saturates increased by 6% to 92% while the resins decreased by 10% to 70% in most cases, compared to the blank. The GC-Mass analysis of the saturate fractions also revealed an increase in the cyclic and branched alkanes and a decrease in the S-containing and N-containing compounds.