Microbiologically-influenced corrosion (MIC): Development of a model system to investigate the role of biofilm communities within MIC and their control using industrial biocides

The challenge in understanding and predicting microbially influenced corrosion (MIC) is the lack of robust and reproducible model biofilm systems that reflect real-world and operating environments. Furthermore, there are no nationally or internationally recognised standards or test methods with which to evaluate control strategies effective against biofilm-mediated corrosion. MIC is a major concern due to the interactions between biofilms and metallic surfaces. Biofilms are surface-adherent microbial communities that are more tolerant towards antimicrobials than planktonic bacteria. Their presence increases rates of corrosion of underlying metals, by providing conducive environments, causing significant damage and representing cost in both repair and management [1]. The associated costs, which have been estimated to amount to $1 billion annually in the US, contribute around 20% of the corrosion to the oil and gas industry alone [2]. Though, the exact mechanism can be difficult to accurately identify within industry. MIC can contribute to corrosion through a variety of different mechanisms. Biocorrosion can occur indirectly through the production of corrosive chemical agents, such as hydrogen sulphide, which causes chemical microbially influenced corrosion (CMIC). Alternatively, direct redox reactions can cause electrical microbially influenced corrosion (EMIC). The different processes make it difficult to correctly assess the threat, identify the appropriate mitigation strategy and effectively manage MIC [3, 4]. This research will develop and validate a representative model system in which inoculate typical of those found in operating pipelines can be cultured as biofilms and investigated. Commercially available biocides as well as novel antimicrobial compounds can then be introduced into the model system and investigated using a combination of techniques including standard microbiological assays, molecular tools, and electrochemical methods. These techniques will be employed to gain a holistic view and to investigate any impact on biofilm viability, changes in prevalence and activity of different species within the biofilm and changes in corrosion rate of the underlying metal. Through investigating the mechanistic relationships in this model system, we aim to provide novel insights into the specific effects of different biocides and potentially highlighting new approaches to biocide development.