Microbially influenced corrosion of carbon steel in the presence of anaerobic sulphate-reducing bacteria

Abstract

Carbon steel is currently being considered as a candidate canister material for use in a deep geological repository of radioactive waste. Assessment of canister material corrosion through microbial activity is an important part of the safety assessment for the final repository. The aim of study was to compare and characterise the corrosion behaviour of carbon steel under sterile and non-sterile anaerobic conditions in natural groundwater containing sulphate-reducing bacteria (SRB). A molecular-biological approach was used to determine the presence and abundance changes of relevant bacterial groups. Carbon steel corrosion rates were higher in the presence of SRB compared with sterile control. EIS described the evolution of three time-constants under non-sterile conditions, while scanning electron microscopy confirmed that the carbon steel surface was covered with a two-layer biofilm. Molecular-biological analysis of the water and biofilm indicated the dominance of SRB, with Desulfomicrobium and Desulfovibrio species prevalent.