Experimental investigation on asphaltene biodegradability using microorganism: cell surface properties’ approach

Asphaltene precipitation is known to be responsible for serious challenges in oil industry such as wellbore damage, oil flow reduction, and plugging of transportation lines. The traditional methods to remove asphaltene deposition are mostly based on chemical solvent. One of the recent proposed green and cost–effect remedial methods is the application of microorganisms capable of consuming the heavy hydrocarbon chains. The cell surface hydrophobicity among others effectively manipulates the efficiency of the microorganism for asphaltene degradation. Besides, surface active agents would affect the microorganism adhesion and cell surface properties, and alters its hydrophobicity. Investigating the effect of these parameters on biodegradability of asphaltene leads to a better understanding of the microorganism effects on asphaltenic oil. In the current investigation, different asphaltenic solutions with the concentration of 2, 4, and 10 g/l are prepared using different southern Iranian crude oil sources, namely Ahwaz-Bangestan and Kuh-e-Mond oil fields. To estimate asphaltene biodegradability, the solutions were used as a carbon source for three different microorganisms namely Enterobacter cloacae, Enterobacter cloacae, and Pseudomonas aeruginosa for a period of 10 days, while the temperature and rotational speed were kept constant under 40 °C and 150 rpm, respectively. The tests were also repeated using sodium dodecyl benzene sulfonate as surface active agent to evaluate the effect of surfactant on microorganism adhesion and cell surface hydrophobicity. The results pointed to the direct effects of the initial concentration of asphaltene in the solution as well as the presence of surfactant which alters the cells hydrophobicity and leads to more asphaltene biodegradability up to 49%.