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Tham khảo tài liệu 'handbook of corrosion engineering episode 1 part 7', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 188 Chapter Two range of habitats and show a surprising ability to colonize water-rich surfaces wherever nutrients and physical conditions allow. Microbial growth occurs over the whole range of temperatures commonly found in water systems pressure is rarely a deterrent and limited access to nitrogen and phosphorus is offset by a surprising ability to sequester concentrate and retain even trace levels of these essential nutrients. A significant feature of microbial problems is that they can appear suddenly when conditions allow exponential growth of the organisms.65 Because they are largely invisible it has taken considerable time for a solid scientific basis for defining their role in materials degradation to be established. Many engineers continue to be surprised that such small organisms can lead to spectacular failures of large engineering systems. The microorganisms of interest in microbiologically influenced corrosion are mostly bacteria fungi algae and protozoans.66 Bacteria are generally small with lengths of typically under 10 pm. Collectively they tend to live and grow under wide ranges of temperature pH and oxygen concentration. Carbon molecules represent an important nutrient source for bacteria. Fungi can be separated into yeasts and molds. Corrosion damage to aircraft fuel tanks is one of the well-known problems associated with fungi. Fungi tend to produce corrosive products as part of their metabolisms it is these by-products that are responsible for corrosive attack. Furthermore fungi can trap other materials leading to fouling and associated corrosion problems. In general the molds are considered to be of greater importance in corrosion problems than yeasts.66 Algae also tend to survive under a wide range of environmental conditions having simple nutritional requirements light water air and inorganic nutrients. Fouling and the resulting corrosion damage have been linked to algae. Corrosive by-products such as organic acids are also associated with .
