Anaerobic corrosion of iron occurs throughout the world and, from an economic standpoint, is quite costly. Sulfate-reducing bacteria, primarily of the genus Desulfovibrio, are responsible for this type of corrosion. It has been postulated that corrosion by these bacteria is caused by their removal of hydrogen from the surface of iron causing it to go into solution. Evidence is presented which indicates that this mechanism may not be responsible for the main corrosive effect of these organisms. These bacteria appear to cause corrosion by producing extracellularly, under anaerobic conditions, a highly corrosive product in addition to hydrogen sulfide. The factors controlling the fate of iron in anaerobic environments, conducive to the growth of sulfate-reducing bacteria, may depend on whether iron sulfide film formation by hydrogen sulfide occurs first, thereby inhibiting corrosion, or whether the highly corrosive substance comes in contact with the iron before film formation has occurred, thereby accelerating corrosion. The antagonistic actions of these two compounds, hydrogen sulfide and the corrosive product, on corrosion produced by sulfate-reducing bacteria, could explain the conflicting observations on anaerobic corrosion noted by investigators in the field and laboratory.
Anaerobic (bacterial) corrosion is an important cause of failures of underground structures such as pipelines. Pipeline failures could be prevented if better methods for determining the presence and location of areas of bacterial corrosion existed. A technique was developed which permits the detection and recording of rapid potential fluctuations (noise) produced in a corroding metal. It is believed that this noise is mainly caused by the breaking of protective films on the metal surface. Anaerobic bacterial corrosion also produces a type of noise, probably due to the breaking of iron sulfide films.
Preliminary evidence indicates that detection and production of this noise on pipelines may offer promise in locating areas of microbial corrosion as well as other types of corrosion. Differences in the type of noise signal could enable differentiation between biological and nonbiological corrosion. Continuing studies should verify or reject these premises.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.