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Optimization of Extraction Conditions for Production of Halophyte-based Biocides for Microbiologically Influenced Corrosion (MIC) Mitigation

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Abstract

Halophytes are plants that grow in saline water and salt-affected soil. To survive these conditions, the plants synthesize various phytochemicals to survive, some of which are biocidal and easily extractable. Offshore structures and subsea pipelines are susceptible to Microbiologically influenced corrosion (MIC) caused by sulfate-reducing prokaryotes (SRP). MIC is especially prevalent due to favorable growth conditions for these microorganisms and is currently mitigated by adding biocides to the pipelines and physically scraping away biofilm. Estimates put MIC at 40% of the corrosion-related maintenance costs. Our previous studies [1] have shown that these halophyte extracts can lower the activity of SRB to negligible levels, lower the relative abundance of common SRB species, and facilitate the breakdown of established biofilms. Different compounds are extracted from the plants as the extraction temperature increases. Some are biocidal, while others can promote growth, such as xylose and other sugars from the breakdown of the plant cells. Moreover, a lower extraction temperature will significantly reduce the production cost on a future commercial scale. Hence, optimization of the extraction temperature is essential. Our current ongoing study examines the biocidal efficacy of extracts from a single halophyte species produced at five different temperatures. Studies are being done in 100 ml serum bottles with Postgate medium and extracts. The bottles are inoculated with a microbial culture from water obtained from a production separator after a MIC afflicted pipeline in the North Sea. Specifics of the process and the plant are part of an ongoing patent application and cannot be disclosed yet. [1] Stein, J. L., Chaturvedi, T., Skovhus, T. L. & Thomsen, M. H. Clean Biocide Project: Halophilic plant extracts for prevention of microbiologically influenced corrosion (MIC). in IWA Biofilm Reactor Conference. Books of Abstracts 154–158 (2021).