Most MIC studies have focused on bacterial involvement; however, under aerobic conditions, other single-celled organisms, such as fungi, yeast and diatoms, can influence corrosion. The predominant types of bacteria associated with MIC are sulfate-reducing bacteria (SRB), sulfur-oxidizing bacteria, iron-oxidizing/reducing bacteria, manganese oxidizing bacteria, and bacteria secreting organic acids and slime. These organisms coexist within a biofilm matrix on metal surfaces, functioning as a consortium in a complex and coordinated manner. The various mechanisms of biocorrosion reflect the variety of physiological activities carried out by these different types of microorganisms when they coexist in biofilms. Despite decades of study on MIC, it is still not known with certainty how many species of microorganisms contribute to corrosion, and researchers continue to report on the formation of biofilms by an ever-widening range of microbial species.
9. Give English equivalents to the following word combinations and learn them by heart:
деятельность микроорганизмов
различные среды
электрохимический процесс
органическая кислота
металлическая поверхность
сероокисляющие бактерии
образование биопленок
микробные виды
аэробные условия
синтетическая коррозия
10. Give Russian equivalents to the following word combinations and learn them by heart:
inhibit corrosion
entire surface
organic acid
hydrogen sulfide
manganese oxidizing bacteria
predominant type
biofilm matrix
physiological activities
11. Translate the following sentences into Russian.
1. Some bacteria can directly reduce metal atoms to ions.
2. Hydrogen ions are produced, along with hydroxyl ions, by the breakdown of water, and the electrons to form atomic hydrogen from the hydrogen ion are produced by the oxidation of atomic iron.
3. The source of electrons is the oxidation of the metal while the electron sink is reduction of hydrogen ions.
4. MIC has been observed as one of the major causes of underground pipeline corrosion.
5. Sulphate reducing bacteria (SRB) have been reported to be responsible for extensive corrosion in hydrocarbon industry.
6. There are other types of corrosion-enhancing bacteria such as iron-reducing bacteria, iron-oxidizing bacteria, nitrifying bacteria, methanogenic bacteria and so on.
7. New technologies that may assist mitigation are basically based on using certain biological technologies (such as use of “good” bacteria against corrosion-related bacteria).
8. Almost all known engineering materials (from carbon steel to stainless and duplex stainless steels and also non-ferrous metals such as copper alloys and non-metals such as some polymers and concrete) are susceptible to MIC.
9. Gas velocity and temperature in the pipeline play a significant role in determining if and where corrosion damage may occur.
10. Accelerated Low Water Corrosion (ALWC) is a particularly aggressive form of MIC that affects steel piles in seawater near the low water tide mark.
12. Translate the following sentences into English.
1. Биокоррозия (от греч. bios – жизнь и позднелат. corrosio – разъедание) – разрушение конструкционных материалов и противокоррозионных защитных покрытий под действием присутствующих в среде микроорганизмов (бактерий, грибов, водорослей, дрожжей).
2. Биокоррозия подразделяется на бактериальную и микологическую.
3. Наиболее опасными микроорганизмами являются бактерии, так как они быстро размножаются и легко приспосабливаются к условиям окружающей среды.
4. Благоприятными условиями для развития плесени является температура 25–35 °C и повышенная влажность воздуха, превышающая 75 %.