A critical review of the literature on microbiological factors involved in the corrosion of iron and steel is presented. A brief account of the historical aspects of the subject is given along with a discussion of the mechanisms by which microorganisms affect corrosion, a description of some typical examples of microbiological corrosion and a discussion of methods used to prevent microbiological corrosion.
It was found that while microorganisms do not corrode iron or steel, they often produce major physical and chemical changes in the environment. These changes may influence the electrochemical processes responsible for corrosion and thus markedly accelerate (or under different conditions decelerate) the corrosion rate.
It was found that microorganisms sometimes coat metal surfaces, influence galvanic cells, affect pH or acidity, affect redox potentials, catalyze chemical reactions which influence corrosion, and change oxygen tension. A description of how anaerobic bacterial corrosion is carried out by sulfate-reducing bacteria is given.
Methods of alleviating microbiological corrosion are found to include cathodic protection, protective coatings, germicide treatment of water, and alkali treatment.
