Effects of selection and fate of substrates supplied to anaerobic bacteria involved in the corrosion of pipe-line steel

Summary The corrosion of AISI C1020 carbon steel in an anoxic, marine, sulphide-containing environment was examined as a function of bacterial physiology and consortial complexity. The carbon steel was exposed to three organism;Eubacterium limosum, Desulfovibrio sp. andDesulfobacter sp. which were provided with H₂/CO₂, butanol, glucose, and acetate as carbon and electron sources. A consortium of these bacteria utilizing hydrogen gave rise to relatively high corrosion rates (5.7×10^–4 mhos cm^–2) with respect to corrosion resulting from bacteria supplied with organic electron sources (0.6–1.6×10^–4 mhos cm^–2). Disproportionation of electrons between sulphate reduction and fermentation had a significant effect on the corrosion rate in the case ofDesulfovibrio. Surface examination using scanning electron microscopy coupled with electrochemical impedance spectroscopy supported the hypothesis that the corrosion rate was controlled by the relative intactness of a ferrous sulphide film in which the bacteria were embedded.