Identification of steel corrosion associated with sulfate-reducing bacteria by electrochemical noise technique

Deterioration of steel structures in natural waters can result from microbiologically influenced corrosion (MIC) such as that caused by sulfate-reducing bacteria (SRB). Corrosion pits associated with MIC have been recently observed in submerged steel bridge piles and there is renewed interest to assess their deterioration. Conventional electrochemical techniques to identify MIC have been complicated due to the effects of the surface films and the mechanism for charge transfer by the bacteria on the steel surface. An electrochemical noise (EN) technique to identify steel corrosion in an aqueous solution has been developed and the method ideally can identify the onset of local pitting, but complications and limitations relating to data acquisition, filtering, and interpretation exist. EN analysis was shown to differentiate SRB and corrosion activity including initial biofilm development, pitting corrosion development, and diminution of SRB activity. Electrochemical behavior, environmental characteristics, SRB activity, and corrosion modality provided consistent correlation to EN and localized corrosion development.