Corrosion Control of Mild Steel by Aerobic Bacteria Under Continuous Flow Conditions

• Published in: Corrosion (Houston, Tex.) Vol. 58; no. 5; pp. 417 - 423
• Main Authors: Ismail, Kh.M., Gehrig, T., Jayaraman, A., Wood, T.K., Trandem, K., Arps, P.J., Earthman, J.C.
• Format: Journal Article
• Language: English
• Published: Houston, TX NACE International 01-05-2002; NACE
• Subjects: Aerobic bacteria; Aerobic conditions; Analytical methods; Applied sciences; Bacteria; Bacterial corrosion; Biofilms; Continuous flow; Corrosion; Corrosion control; Corrosion effects; Corrosion prevention; Corrosion rate; Electrochemical impedance spectroscopy; Electrochemistry; Exact sciences and technology; Flow rates; Flow system; Flow velocity; Low carbon steels; Metals. Metallurgy; Monoculture; Monoculture (aquaculture); Nutrient flow; Oxic conditions; Pseudomonas fragi; Scavenging; Spectroscopy; Steel; Corrosion resistance; Mild steel; Aerobiosis; Corrosion; Electrochemical method; Check; Bacteria; Steel; Bacterial corrosion; Experimental study; Corrosion protection
• DOI: 10.5006/1.3277631
• EISSN: 1938-159X
• ISSN: 0010-9312

ABSTRACTCorrosion of mild steel under aerobic conditions in the presence of a monoculture of aerobic bacteria (Pseudomonas fragi K [P. fragi K]) has been studied in a continuous flow system using electrochemical impedance spectroscopy (EIS). P. fragi K grown in Luria-Bertani (LB) medium causes a 10- to 20-fold decrease in the corrosion rate of mild steel after a biofilm becomes visible on the surface of the samples. Live viable bacteria are necessary for the observed corrosion reduction of mild steel, indicating an active role rather than a barrier effect of the biofilm. Flowing nitrogen through the solution was found to be less effective than P. fragi K in lowering the corrosion rate of mild steel, suggesting that an effect by bacteria, in addition to scavenging oxygen, is involved. The effect of nutrient flow rate on the ability of the bacteria toThe presence of bacterial biofilms is often shown to be associated with elevated corrosion rates.1-2 These attached bacterial colonies can cause serious damage to structures exposed to soil, fresh water, and seawater, and they will affect a variety of metals.3 Controlling the growth of these bacterial colonies with biocides has proven to be very difficult because cells in a biofilm can be up to 500 times more resistant to antibacterial agents than those in fluid suspension. While antibiotics have been designed to kill suspended cells, biofilm bacteria undergo phenotypic changes that make them entirely different from those in suspension.4-7 Furthermore, since no inherently colonizationresistant material has yet been found, there has been no easy answer to this problem.8 Several studies have shown, however, that certain bacterial systems decrease corrosion rates.9-15 In particular, work performed by Pedersen and Hermansson has shown that substantial corrosion reduction is possible in mild steel exposed to monocultures of Pseudomonas sp.S9 and Serratia marcescens EF190 compared to a sterile control.11-12 Pedersen and Hermansson and Jayaraman, et al.,13-14 suggest that this protective behavior was the result