Influence of Microorganisms on Corrosion Induction and Protection
The microbial corrosion or the microbiologically induced corrosion (MIC) is defined as the deterioration of metals as a result of metabolic activities of microorganisms. MIC leads to important economical losses in many industries and services. Anaerobic Sulfate-reducing bacteria (SRB) is a serious type of MIC commonly found in the oil and gas industry sector and are responsible for most highly corrosion damages to offshore steel structures. The SRB present in the crude oil uses the sulfate as an electron acceptor generating corrosive hydrogen sulfide (H2S) as one of their products. Other types of MIC are the aerobic iron and manganese bacteria mainly responsible about the accelerated pitting attacks of stainless steel. Most MIC takes the form of pits that form below the colonies of living organic matter and mineral and the deposits of biological origin. The most affected devices by MIC are stainless and carbon steel tanks, pipelines, heat exchangers, fuel storage tanks. On the other hand, many beneficial bacteria, (such as Bacillus lichiniformis) have the ability to protect metal surfaces from corrosion via different mechanisms including biofilms and formation of sticky protective layer of γ-poly-glutamate or antibiotics on metal surfaces. The aim of the present work is to present a spotlight on the history and the role of microorganisms in corrosion induction and prevention. This chapter includes corrosion inhibition mechanisms employing beneficial microorganisms with special reference to microbial biofilms to avoid the dramatic economic loss due to corrosion. On the contrary, different types of harmful microorganisms included in corrosion are also discussed including iron and sulfur reducing bacteria.
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