Corrosion of Mild Steel by Actively Growing Cultures of Sulphate-Reducing Bacteria. The Influence of Ferrous Iron

Abstract

The rate of corrosion of mild steel has been studied in the presence of actively growing pure cultures of a number of different strains of sulphate reducing bacteria using a culture medium containing sufficient ferrous iron to prevent the accumulation of free sulphide ions in the culture and hence to prevent the direct interaction between the metal and sulphide ions to give partially protective films. This was only partially successful in so far as some patchy film formation was experienced. Nevertheless, it was found that all the bacteria induced corrosion to approximately the same extent and that corrosion time curves were essentially linear. There was no relationship observable between the rate of corrosion and the hydrogenase activity of the bacteria. Desulfotomaculum orientis, an organism previously thought to be relatively innocuou, was found to show hydrogenase activity in the conditions used and to be almost equally aggressive as Desulfovibrio desulfuricans.