Microbial Corrosion of X60 Pipeline Steel in Groundwater Containing Sulfate-Reducing Bacteria/Iron-Oxidizing Bacteria Mixed Colonies

Microbial corrosion of X60 pipeline steel was examined by polarization scan, electrochemical impedance spectroscopy, scanning electron microscopy, x-ray diffractometry, and energy dispersive spectroscopy during and after immersion in a groundwater environment containing mixed colonies of anaerobic sulfate-reducing bacteria (SRB) and aerobic iron-oxidizing bacteria (IOB). The results show that individual SRB and IOB affected the electrochemical process of steel, and they also have a significant synergistic effect on intensifying microbial proliferation and promoting corrosion. IOB improved the metabolic activities of SRB by O 2 consumption and biofilm formation, thus creating a suitable anaerobic environment for SRB and promoting localized corrosion. The corrosion process of the steel in SRB/IOB mixed culture was influenced comprehensively by dissolved oxygen, steel/biofilm interactions, metabolic activities, and by-products.