The decreasing deposit of fossil energy will promote the finding of alternative energy sources. Biofuels namely biodiesel, commonly mix with the diesel oil when used as energy sources. This kind of fuel is typically stored in a storage tank constructed from carbon steel. Carbon steel is preferred for the storage tank due to its good mechanical properties and relatively inexpensive material. However, the material can be easily corroded by microorganisms. In the storage tank, corrosion can occur, because microorganisms are capable of utilizing hydrocarbons as a nutrient source and forming a biofilm on the surface of the metal. Literatures showed that Bacillus sp. are species that dominate the biodegradation of petroleum hydrocarbons. With increasing role of biofuels, the corrosion resistance of the storage material should be improved, because this alternative fuel is one of the potential growth medium of microorganisms leading to biocorrosion.
This research project mainly focus on the investigation of concentration variation of biodiesel (15%, 20%, and 30% v/v) in diesel oil and types of microorganisms influencing the biocorrosion. In this study, the corrosion process was investigated through the evaluation of biofilm morphology and composition, and the corrosion product of carbon steel which was exposed in the mixture of hydrocarbons and the presence of B. megaterium.