Microbial corrosion, also called microbiologically influenced corrosion (MIC), microbially induced corrosion (MIC) or biocorrosion, is "

corrosion Corrosion is a natural process that converts a refined metal into a more chemically stable oxide. It is the gradual deterioration of materials (usually a metal) by chemical or electrochemical reaction with their environment. Corrosion engi ...

affected by the presence or activity (or both) of microorganisms in

biofilms A biofilm comprises any syntrophic consortium of microorganisms in which cells stick to each other and often also to a surface. These adherent cells become embedded within a slimy extracellular matrix that is composed of extracellular po ...

on the

surface A surface, as the term is most generally used, is the outermost or uppermost layer of a physical object or space. It is the portion or region of the object that can first be perceived by an observer using the senses of sight and touch, and is ...

of the corroding

material Material is a substance or mixture of substances that constitutes an object. Materials can be pure or impure, living or non-living matter. Materials can be classified on the basis of their physical and chemical properties, or on their geolo ...

." This corroding material can be either a

metal A metal (from Greek μέταλλον ''métallon'', "mine, quarry, metal") is a material that, when freshly prepared, polished, or fractured, shows a lustrous appearance, and conducts electricity and heat relatively well. Metals are typicall ...

(such as steel or aluminum alloys) or a nonmetal (such as

concrete Concrete is a composite material composed of fine and coarse aggregate bonded together with a fluid cement (cement paste) that hardens (cures) over time. Concrete is the second-most-used substance in the world after water, and is the most wid ...

glass Glass is a non-crystalline, often transparent, amorphous solid that has widespread practical, technological, and decorative use in, for example, window panes, tableware, and optics. Glass is most often formed by rapid cooling ( quenching ...

Bacteria

Some

sulfate-reducing bacteria Sulfate-reducing microorganisms (SRM) or sulfate-reducing prokaryotes (SRP) are a group composed of sulfate-reducing bacteria (SRB) and sulfate-reducing archaea (SRA), both of which can perform anaerobic respiration utilizing sulfate () as termina ...

produce hydrogen sulfide, which can cause sulfide stress cracking. ''

Acidithiobacillus ''Acidithiobacillus'' is a genus of the ''Acidithiobacillia'' in the " Pseudomonadota". The genus includes acidophilic organisms capable of iron and/or sulfur oxidation. Like all ''"Pseudomonadota"'', ''Acidithiobacillus'' spp. are Gram-negative ...

'' bacteria produce sulfuric acid; ''Acidothiobacillus thiooxidans'' frequently damages sewer pipes. '' Ferrobacillus ferrooxidans'' directly oxidizes

iron Iron () is a chemical element with Symbol (chemistry), symbol Fe (from la, Wikt:ferrum, ferrum) and atomic number 26. It is a metal that belongs to the first transition series and group 8 element, group 8 of the periodic table. It is, Abundanc ...

to iron oxides and iron hydroxides; the rusticles forming on the RMS ''Titanic'' wreck are caused by bacterial activity. Other bacteria produce various acids, both organic and mineral, or

ammonia Ammonia is an inorganic compound of nitrogen and hydrogen with the formula . A stable binary hydride, and the simplest pnictogen hydride, ammonia is a colourless gas with a distinct pungent smell. Biologically, it is a common nitrogenous wa ...

. In presence of oxygen,

aerobic bacteria Aerobic means "requiring air," in which "air" usually means oxygen. Aerobic may also refer to * Aerobic exercise, prolonged exercise of moderate intensity * Aerobics, a form of aerobic exercise * Aerobic respiration, the aerobic process of cell ...

like ''Acidithiobacillus thiooxidans'', ''Thiobacillus thioparus'', and ''Thiobacillus concretivorus'', all three widely present in the environment, are the common corrosion-causing factors resulting in

biogenic sulfide corrosion Biogenic sulfide corrosion is a bacterially mediated process of forming hydrogen sulfide gas and the subsequent conversion to sulfuric acid that attacks concrete and steel within wastewater environments. The hydrogen sulfide gas is biochemically ox ...

. Without presence of oxygen, anaerobic bacteria, especially ''Desulfovibrio'' and ''Desulfotomaculum'', are common. ''Desulfovibrio salixigens'' requires at least 2.5% concentration of sodium chloride, but ''D. vulgaris'' and ''D. desulfuricans'' can grow in both fresh and salt water. ''D. africanus'' is another common corrosion-causing microorganism. The genus ''Desulfotomaculum'' comprises sulfate-reducing spore-forming bacteria; ''Dtm. orientis'' and ''Dtm. nigrificans'' are involved in corrosion processes. Sulfate-reducers require reducing environment; an electrode potential lower than -100 mV is required for them to thrive. However, even a small amount of produced hydrogen sulfide can achieve this shift, so the growth, once started, tends to accelerate. Layers of anaerobic bacteria can exist in the inner parts of the corrosion deposits, while the outer parts are inhabited by aerobic bacteria. Some bacteria are able to utilize

hydrogen Hydrogen is the chemical element with the symbol H and atomic number 1. Hydrogen is the lightest element. At standard conditions hydrogen is a gas of diatomic molecules having the formula . It is colorless, odorless, tasteless, non-toxic ...

formed during cathodic corrosion processes. Bacterial colonies and deposits can form

concentration cell In battery technology, a concentration cell is a limited form of a galvanic cell that has two equivalent half-cells of the same composition differing only in concentrations. One can calculate the potential developed by such a cell using the Nernst ...

s, causing and enhancing galvanic corrosion

Bacterial corrosion may appear in form of pitting corrosion, for example in pipelines of the oil and gas industry. Anaerobic corrosion is evident as layers of metal sulfides and hydrogen sulfide smell. On

cast iron Cast iron is a class of iron– carbon alloys with a carbon content more than 2%. Its usefulness derives from its relatively low melting temperature. The alloy constituents affect its color when fractured: white cast iron has carbide impur ...

, a graphitic corrosion selective leaching may be the result, with iron being consumed by the bacteria, leaving

graphite Graphite () is a crystalline form of the element carbon. It consists of stacked layers of graphene. Graphite occurs naturally and is the most stable form of carbon under standard conditions. Synthetic and natural graphite are consumed on lar ...

matrix with low mechanical strength in place. Various

corrosion inhibitor In chemistry, a corrosion inhibitor or anti-corrosive is a chemical compound that, when added to a liquid or gas, decreases the corrosion rate of a material, typically a metal or an alloy, that comes into contact with the fluid. The effectiveness ...

s can be used to combat microbial corrosion. Formulae based on

benzalkonium chloride Benzalkonium chloride (BZK, BKC, BAK, BAC), also known as alkyldimethylbenzylammonium chloride (ADBAC) and by the trade name Zephiran, is a type of cationic surfactant. It is an organic salt classified as a quaternary ammonium compound. ADBACs ha ...

are common in oilfield industry. Microbial corrosion can also apply to

plastic Plastics are a wide range of synthetic or semi-synthetic materials that use polymers as a main ingredient. Their plasticity makes it possible for plastics to be moulded, extruded or pressed into solid objects of various shapes. This adaptab ...

, and many other materials. Two examples are Nylon-eating bacteria and Plastic-eating bacteria.

Aviation fuel

Hydrocarbon utilizing microorganisms, mostly '' Cladosporium resinae'' and ''

Pseudomonas aeruginosa ''Pseudomonas aeruginosa'' is a common encapsulated, gram-negative, aerobic–facultatively anaerobic, rod-shaped bacterium that can cause disease in plants and animals, including humans. A species of considerable medical importance, ''P. aerug ...

'' and

Sulfate Reducing Bacteria Sulfate-reducing microorganisms (SRM) or sulfate-reducing prokaryotes (SRP) are a group composed of sulfate-reducing bacteria (SRB) and sulfate-reducing archaea (SRA), both of which can perform anaerobic respiration utilizing sulfate () as termina ...

, colloquially known as "HUM bugs", are commonly present in jet fuel. They live in the water-fuel interface of the water droplets, form dark black/brown/green, gel-like mats, and cause microbial corrosion to plastic and rubber parts of the aircraft fuel system by consuming them, and to the metal parts by the means of their acidic metabolic products. They are also incorrectly called algae due to their appearance. FSII, which is added to the fuel, acts as a growth retardant for them. There are about 250 kinds of bacteria that can live in jet fuel, but fewer than a dozen are meaningfully harmful.

Nuclear waste

Microorganisms can negatively affect radioactive elements confined in

nuclear waste Radioactive waste is a type of hazardous waste that contains radioactive material. Radioactive waste is a result of many activities, including nuclear medicine, nuclear research, nuclear power generation, rare-earth mining, and nuclear weapons ...

Sewerage

Sewer network structures are prone to biodeterioration of materials due to the action of some microorganisms associated to the sulfur cycle. It can be a severely damaging phenomenon which was firstly described by Olmstead and Hamlin in 1900 for a brick sewer located in Los Angeles. Jointed mortar between the bricks disintegrated and ironwork was heavily rusted. The mortar joint had ballooned to two to three times its original volume, leading to the destruction or the loosening of some bricks. Around 9% of damages described in sewer networks can be ascribed to the successive action of two kinds of microorganisms.

Sulfate-reducing bacteria Sulfate-reducing microorganisms (SRM) or sulfate-reducing prokaryotes (SRP) are a group composed of sulfate-reducing bacteria (SRB) and sulfate-reducing archaea (SRA), both of which can perform anaerobic respiration utilizing sulfate () as termina ...

(SRB) can grow in relatively thick layers of sedimentary sludge and sand (typically 1 mm thick) accumulating at the bottom of the pipes and characterized by anoxic conditions. They can grow using oxidized sulfur compounds present in the effluent as electron acceptor and excrete hydrogen sulfide (H₂S). This gas is then emitted in the aerial part of the pipe and can impact the structure in two ways: either directly by reacting with the material and leading to a decrease in pH, or indirectly through its use as a nutrient by sulfur-oxidizing bacteria (SOB), growing in oxic conditions, which produce biogenic sulfuric acid.Islander et al., 1991; Roberts et al., 2002; Okabe et al., 2007 The structure is then submitted to a biogenic sulfuric acid attack. Materials like

calcium aluminate cements Calcium aluminate cements are cements consisting predominantly of hydraulic calcium aluminates. Alternative names are "aluminous cement", "high-alumina cement" and "Ciment fondu" in French. They are used in a number of small-scale, specialized ap ...

, PVC or vitrified clay pipe may be substituted for ordinary concrete or steel sewers that are not resistant in these environments. Mild steel corrosion reduction in water by uptake of dissolved oxygen is carried out by Rhodotorula mucilaginosa(7).

References

* Olmstead, W.M., Hamlin, H., 1900. Converting portions of the Los Angeles outfall sewer into a septic tank. Engineering News 44, 317–318. * Kaempfer, W., Berndt, M., 1999. Estimation of service life of concrete pipes in sewer networks. Durability of Building Materials and Components 8, 36–45. * Islander, R.L., Devinny, J.S., Mansfeld, F., Postyn, A., Shih, H., 1991. Microbial ecology of crown corrosion in sewers. Journal of Environmental Engineering 117, 751–770. * Roberts, D.J., Nica, D., Zuo, G., Davis, J.L., 2002. Quantifying microbially induced deterioration of concrete: initial studies. International Biodeterioration and Biodegradation 49, 227–234. * Okabe, S., Odagiri, M., Ito, T., Satoh, H., 2007. Succession of sulfur-oxidizing bacteria in the microbial community on corroding concrete in sewer systems. Applied and Environmental Microbiology 73, 971–980. * Mansouri, H., Alavi, S. A., & Fotovat, M.
Microbial Influenced Corrosion of Corten Steel Compared to Carbon Steel and Stainless Steel in Oily Waste Water by Pseudomonas Aeruginosa.
JOM, 1–7. *Madhusudan P Dabhole and K N Joishy.2003 Mild steel corrosion reduction in water by uptake of dissolved oxygen by Rhodotorula mucilaginosa.Journal of Scientific and Industrial Research,Vol. 62, no. 7, P 683-689.

Notes

External links

Dialog to odor and biogenic corrosion in sewage, exhaust air arrangements and fermentation gas arrangements