The effect of different bacteria's on microbiological influenced corrosion behaviour on light alloys

Pipe systems are part of our manmade environments. They can be found in urban environment where it is usually used to transfer water or sewage, in industrial environment where it can carry hazardous waste (for instance in the chemical industry), or oil and its products in the petroleum industry. Leakage in all pipe system is an unwelcome event. The physical presence of microbial cells on a metal surface, as well as their metabolic activities, can cause Microbiologically Influenced Corrosion (MIC) or biocorrosion. It is caused usually by chemoautotrophs microorganisms. MIC is a problem in many industry areas. It can apply to both metals and non-metallic materials. The presence of bacteria could increase tenfold the corrosion rate; such corrosion rate can cause failure of pipelines within a year or two. Within this research we have investigated the phenomenon of MIC by testing several parameters such as the effect of different bacteria (Bacillus thuringiensis, Staphylococcus aureus and mixture of bacteria). The MIC was studied for Aluminum 5052 and steel St-57 under two incubation conditions. Corrosion was studied by using three different measurements: weight loss, Potentiodynamic and Impedance spectroscopy in order to have a comprehensive and accurate data. The result shows that Staphylococcus aureus is more corrosive to steel then Bacillus thuringiensis or the bacterial mixture. We have also found higher corrosion rates at higher temperature (37°C). We would like to suggest the idea of "probiotic" bacteria to piping, i.e. "good bacteria" will generate biofilm inside piping and could influence the corrosion control for MIC.