Effect of bacteria on the corrosion resistance of structural metals in water sources and systems

Pipe systems are part of our manmade environments. They can be found in urban environments, where they are usually used to transfer water or sewage, in industrial environments, where they can carry hazardous waste, or in the petroleum industry, where they carry oil and its products. Leakage in all pipe systems 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. The presence of bacteria could significantly increase the corrosion rate, which could cause failure of pipelines within a year or two. The long term goal of the project is to develop biological and non-biological ways to control MIC. Towards this goal the MIC phenomenon was investigated by testing several parameters, such as the effect of different bacteria on different alloys, and under two incubation conditions. Corrosion was studied by using three different measurements - weight loss, potentiodynamic spectroscopy, and impedance spectroscopy - to produce comprehensive and accurate data. The results show that some bacteria are more corrosive to steel than others. The study concluded with a finding that further investigation is essential in order to develop water tanks and systems that are corrosion-controlled.