Effects of Hydrodynamic Environment on the Interaction of Shewanella oneidensis with Low Carbon Steel and the Impacts on Corrosion

Microbiologically influenced corrosion (MIC) impacts various industries such as oil/gas production and transmission, wastewater treatment, power generation, and chemical processing. In such settings, the combined impacts of microbiological activities and fluid flow dynamics could be primary controllers of metal corrosion. We examined the relative influences of fluid flow and the activities of the facultative Fe(III) reducing bacterium, Shewanella oneidensis MR-1, on the corrosion of carbon steel. Rotating cylinder electrode experiments were used to determine the shear stress and velocity at the surface of the metal coupon in a newly constructed flow system. The system was then used to study the impact of increasing fluid velocity and shear stress on the corrosion rate of coupons in O₂-limited and O₂-nonlimited incubations. Confocal scanning laser microscopy was used to monitor biofilm development on the metal surface at increasing shear stress. We found that the activities of S. oneidensis inhibited corrosion, even under conditions of high shear stress and limited attachment, indicating that the respiratory consumption of O₂ by planktonic S. oneidensis protects the metal surface from enhanced corrosion.