Review Article on the Influence of Dissolved Oxygen on Sulfate-Reducing Bacteria Related Corrosion

Corrosion by sulfate-reducing bacteria (SRB) has been intensively studied during the last 40 years, but until now the importance of oxygen in SRB-related corrosion has rarely been emphasized (Hardy and Bown, 1984; Starkey, 1985; Hamilton, 1990; Hamilton, 1991). The impact of oxygen on SRB-related corrosion is attributed to a direct effect on the sulfur-related corrosion products rather than to any stimulation of SRB activity (Hamilton, 1990; Hamilton, 1991). Pitting corrosion is the characteristic mode of attack and deep pit is usually found underneath a porous corrosion products. However, the role that oxygen plays in the aerobic/anaerobic environments in relation to corrosion has not been clearly defined. The system is complex and dynamic. The role of SRB must be viewed in the context of biological consortia (biofilms) and/or mixed ecosystems. In addition to the biological factors, the chemical environments which influence corrosion are also complicated by the introduction of oxygen. The following statement is quoted from Starkey. “ Factors that have been suggested or may be concerned with anaerobic corrosion relate particularly to the effect of ferrous sulfide, sulfur, ferrous hydrate and all other products of the corrosion process, differential aeration cells, and various combinations of all of those factors”. In this review, we intended to focus on aspects of experimental systems that more accurately reflect those environmental conditions generally associated with corrosion in the field. Describing the role of dissolved oxygen on SRB-related corrosion, we will summarize the current published papers which describe the corrosion of mild steel underneath aerobic biofilms containing SRB (Lee and Characklis, 1990; Lee et al. 1992). Finally, we will discuss various experimental approaches in an attemp to elucidate the true mechanism of SRB-related corrosion in aerobic environments.