Experiments were designed to answer the following questions: Are issues for storing alternative fuels in contact with natural seawater different from those experienced with petroleum-based fuels? Does initial oxygen concentration in the seawater and fuel phases affect biodegradation? What roles do the differences in seawater compositions (chemical and microbiological) play in the degradation of alternative fuels and the resulting corrosion?
Under typical storage conditions, dissolved oxygen in seawater in contact with conventional petroleum-based (JP5 and F76) and alternative bio-based (camelina-derived JP5, algal-derived F76 and fatty acid methyl ester) fuels stored with uncoated carbon steel was reduced <100 ppb within days due to oxygen consumption by corrosion reactions and aerobic respiration. Sulfides, produced by anaerobic sulfate-reducing bacteria, and chlorides were co-located in corrosion products in both the seawater and fuel phases.
Transient oxygen influenced both metabolic degradation pathways and resulting metabolites. Catechols, indicative of aerobic degradation, and typically aerobic bacteria persisted after 90-day exposures. Detection of catechols suggested that initial exposure to oxygen resulted in their formation.
Two different seawaters, Coastal Key West, FL, USA and Persian Gulf seawaters, representing an oligotrophic and a more organic- and inorganic mineral-rich environment, respectively, were used to evaluate the effect of seawater properties on biodegradation and corrosion.