The diversity and degradation capacity of hydrocarbon-degrading consortia from surface and deep waters of the Eastern Mediterranean Sea were studied in time-series experiments. Microcosms were set up in ONR7a medium at in situ temperatures of 25 °C and 14 °C for the Surface and Deep consortia, respectively, and crude oil as the sole source of carbon. The Deep consortium was additionally investigated at 25 °C to allow the direct comparison of the degradation rates to the Surface consortium. In total, ~50% of the alkanes and ~15% of the polycyclic aromatic hydrocarbons were degraded in all treatments by Day 24. Approximately ~95% of the total biodegradation by the Deep consortium took place within 6 days regardless of temperature, whereas comparable levels of degradation were reached on Day 12 by the Surface consortium. Both consortia were dominated by well-known hydrocarbon-degrading taxa. Temperature played a significant role in shaping the Deep consortia communities with Pseudomonas and Pseudoalteromonas dominating at 25 °C and Alcanivorax at 14 °C. Overall, the Deep consortium showed a higher efficiency for hydrocarbon degradation within the first week following contamination, which is critical in the case of oil spills, and thus merits further investigation for its exploitation in bioremediation technologies tailored to the Eastern Mediterranean Sea.

Light cycle oil (LCO) can obtain the characteristics of a good diesel fuel-blending component, if first it has been upgraded. Solvent extraction is a method of choice, mostly due to the process economics. In this work the influence of temperature and solvent to feed ratio (S/F) in LCO extraction with acetonitrile was studied. Detailed composition of the extraction products was assessed by gas chromatography-mass spectrometry and high performance liquid chromatography. S/F ratio found to influence process performance more drastically compared to the temperature. Increase of S/F ratio decreases raffinate yield, while leading to a better product quality. Based on the results of this work, the extraction process can be optimized to achieve the highest possible raffinate yield with adequate properties as diesel fuel component.