Microbiologically Induced Corrosion of Aluminum Alloy by Manganese Oxidizing Bacterium

Abstract

As the most preferred fuel in passenger aircraft Jet A-1 is one of the kerosene-type fuels used as a carbonsource by microorganisms in aircraft fuel tanks. Bacteria inevitably multiply on the tank surfaces incontact with the fuel to provide their metabolic needs, causing both maintenance costs and safetyproblems due to microbiologically induced corrosion (MIC) and biofilm formation. Manganeseoxidizing bacteria (MOB) are considered as one of the groups of corrosion-causing microorganisms.Therefore, in order to reduce/prevent MIC in aircraft fuel tanks, it may be essential to investigate thecorrosive effects of MOB on the fuel tank surfaces.The aim of this study is to determine whether MOB isolated from the jet A-1 fuel cause the MIC of7175-T7351 aluminum alloy, which is frequently used as an aircraft fuel tank material. For this purpose,corrosion experiments were carried out in a lab-scale test system set up with the 1 g/L final Mnconcentration. The MIC of the aluminum coupons was determined by the gravimetric method as well asby investigating the Mn oxidation ability of MOB strain during the experiment.Mn oxidation of the MOB strain detected after 25 days of exposure continued increasingly until the endof the experiment. Aluminum coupons were corroded by the MOB strain from the first sampling day ofthe experiment. It was determined that the ratio of corrosion rate in the test system to the control systemat the end of the experiment was 2 times higher than the rate on the 4 day of exposure, which is the firstsampling day of the experiment.