Microbiologically Influenced Corrosion Capability of Bacteria Isolated from Yucca Mountain

• Published in: Corrosion (Houston, Tex.) Tex.), 2004-01, Vol.60 (1), p.64-74
• Main Authors: Pitonzo, B.J., Castro, P., Amy, P.S., Southam, G., Jones, D.A., Ringelberg, D.
• Format: Article
• Language: English
• Subjects: Applied sciences; Bacteria; Bacterial corrosion; Biofilms; Bridges; Calomel electrode; Carbon steels; Corrosion; Corrosion cell; Corrosion environments; Corrosion mechanisms; Corrosion rate; Corrosion resistance; Corrosion tests; Electrochemical corrosion; Electrochemistry; Electrode polarization; Electrodes; Electron microscopy; Exact sciences and technology; Exopolysaccharides; Fatty acids; Groundwater; Inoculation; Iron; Iron-oxidizing bacteria; Light microscopy; Metals. Metallurgy; Microorganisms; Microscopy; Mountains; Optical microscopy; Oxidation; Phospholipids; Pitting (corrosion); Platinum; Potassium; Potassium chloride; Scanning electron microscopy; Stabilizing; Sulfate reduction; Sulfate-reducing bacteria; Sulfates; Sulphate reduction; X ray analysis; X-ray spectroscopy
• ISSN: 0010-9312; 1938-159X
• DOI: 10.5006/1.3299233

ABSTRACTMicroorganisms, implicated in microbiologically influenced corrosion, were isolated from the deep subsurface at Yucca Mountain. Corrosion rates of iron-oxidizing, sulfate-reducing, and exopolysaccharide (EPS)-producing bacteria were examined in constructed electrochemical corrosion cells for periods up to 109 days. The test system consisted of a 1020 carbon steel (CS) coupon immersed in soft R2A agar prepared with simulated groundwater. A 1% potassium chloride (KCl) bridge was used to connect the test to a reference calomel electrode and a potential was applied with a platinum counter electrode. The corrosion process was measured by polarization resistance methodology. Average corrosion rates were measured in milli-inches per year (mpy) against time. Purified cultures of EPS-producing bacteria and enrichment cultures of iron-oxidizing and sulfate-reducing bacteria were tested separately and in various combinations. An uninoculated control cell was prepared to assess abiotic corrosion. The corrosion rates peaked at 35 days at 1.2 mpy (control), 2.3 mpy (iron-oxidizing bacteria), 3.30 mpy (sulfate-reducing bacteria), and 2.8 mpy (EPS-producing bacteria) before stabiCorrosion traditionally has been regarded as a sequence of electrochemical reactions at a metal surface in contact with an aqueous electrolyte-containing solution.1 This results in the dissolution of metal from anodic sites with subsequent electron acceptance at cathodic sites.2 However, it is now known that corrosion reactions actually may be induced or enhanced by microbial activity.2-3 Microorganisms implicated in microbiologically influenced corrosion (MIC) include iron-oxidizing, sulfate-reducing, acidproducing, and exopolymer-producing bacteria.1,4 When a metallic surface is immersed in an aqueous solution, a conditioning film of carbon and other nutrients forms on the surface, which attracts bacteria,