Biofilms microbiologically influenced corrosion

When biofilms are formed on metallic surfaces, they can seriously corrode performance oil production facilities, chemical processing plants, paper mills, ships, and water distribution networks. Microbiologically influenced corrosion (MIC) represents the most serious form of that degradation. 

G.G. Geesey, Biofilm Formation, A Practical Manual on Microbiologically Influenced Corrosion, Gregory Kobrin, Ed., NACE International, 1993, p 11-13... 

B. C. Syrett, P. J. Arps, J. C. Earthman et al.. Biofilms that prevent corrosion in Proc. Symp. Microbiologically Influenced Corrosion , CORROSION/2002 (Ed. B. Little), NACE International, Houston, Tex., 2002, pp. 145-154. 

Zhang, H. J. and Dexter, S. C., Effect of Biofilms on Critical Pitting Potentials for Stainless Steels S30400 and S31600 in Seawater, International Conference on Microbiologically Influenced Corrosion, P. Angell, Ed., NACE International, Houston, TX, 1995, pp. 70-71. 

Microbiologically influenced corrosion (MIC) is used to designate corrosion resulting from the presence and activities of microorganisms within biofilms on a material surface. Such microorganisms can accelerate and control corrosion reactions by several mechemisms formation of differential or concentration cells, formation of metabolites, such as sulfides md organic and inorganic acids metal oxidation and reduction, and deactivation of corrosion inhibitors. 

Control of MIC. Microorganisms in the injection water and produced water may have the opportunity to attach to metal surfaces in regions of low flow rates. If allowed to form biofilms, the microorganisms could contribute to microbiologically influenced corrosion (MIC) of the injection system. MIC events in the injection system can lead to corrosion failures of pipelines and pumps, with the related problems of equipment downtime, lost production and environmental hazards caused by spills or releases. It is safe to say that the overwhelming purpose of using biocides in the oilfield is to control MIC. 

Biofilm [I, 5./.]. A biofilm is an organic film containing microorganisms embedded in polymeric substances. Biofilms typically consist of water, microorganisms, extracellular polymeric substances (EPS), embedded particles and debris, and dissolved substances. The unchecked development of biofilms on paper machines can result in sheet defects, breaks, malodours, and Microbiologically Influenced Corrosion (M.I.C.). 

Geesey GG (1993) Biofilm formation. In A practical manual on microbiologically-influenced corrosion Kobrin G (ed) NACE Houston Texas USA... 

Kobrin G, Tatnall RE (1993) Introduction a practical manual on microbiological influenced corrosion. NACE International, Houston, pp 68-72 Koenig DW, Mishra SK, Pierson DL (1995) Removal of Burkholderia Cepacia biofilms with oxidants. Biofouling 9 51-62 Kong K, Johnstone DL, Yonge DR, Petersen JN, Brouns TM (1994) Long-term intracellular chromium partitioning with subsurface bacteria. Appl Microbiol Biotechnol 42 403 07... 

Geesey, G. G., Introduction Part II—Biofilm Formation, in Kobrin, G. (ed.), Microbiologically Influenced Corrosion, Houston, NACE International, 1993. 

More recently, attention has been directed to the "ninth form of corrosion, biologically influenced corrosion, which includes studies on an area referred to as "ennoblement. The presence of biofilms on metals and alloys immersed in natural seawater produces a complex, heterogeneous chemistry along the metallic surface. It has usually been observed that passive alloys such as aluminum, stainless steels, nickel-base alloys, or titanium show an increase to more noble (electropositive) potentials or ennoblement of several hundred millivolts with exposure time in natural seawater, thus magnifying the potential differences that may exist between dissimilar alloys [26,55-64]. Ennoblement is likely caused by the formation of microbiological films, which increase the kinetics of the cathodic reaction [55-63],... 

The presence of a biofilm on a metallic surface can greatly alter the local corrosion processes. In addition to the electrochemical changes that directly affect corrosion, biofilms can also modify other readily measured characteristics such as pressure drop or heat transfer resistance. Monitoring such microbiological influences can provide a useful indicator that a biofilm is present and that action should be taken to mitigate potential MIC. 

Stein AA (1993) MIC treatment and prevention. In A practical manual on microbiologi-cally-influenced corrosion Kobrin G (ed) NACE Houston Texas USA Lee J (1998) Bacterial biofilms less likely on electropolished steel Agricultural Res p. 10 Percival SL, Knapp JS, Wales DS, Edyvean RGJ (2000) Metal and iuorgauic ion accumulation in biofihns exposed to flowing and stagnant water. Brit Corrosion J 36(2) 105-110 Sreekumari KR, Nandakumar K, Kikuchi Y (2004) Effect of metal microstructure on bacterial attachment A contributing factor for preferential mic attack of welds. Paper No. 04597. CORROSION 2004, NACE International... 

---