Filtration–UV irradiation as an option for mitigating the risk of microbiologically influenced corrosion of subsea construction alloys in seawater

• Biofilms ennobled Ecorr of offshore construction alloys in natural seawater.
• Filtration–UV irradiation delayed biofilm growth and activity on alloys.
• Localized corrosion in seawater was lowered by the use of filtration–UV irradiation.
• Biofilm community composition was affected by both substratum and seawater treatment.
• Filtration–UV irradiation can be an ecofriendly practice for protection against MIC.

The effect of filtration–UV irradiation of seawater on the biofilm activity on several offshore structural alloys was evaluated in a continuous flow system over 90 days. Biofilms ennobled the electrode potential by +400 to 500 mV within a few days of exposure to raw untreated seawater. Filtration–UV irradiation of the seawater delayed the ennoblement of the steels for up to 40 days and lowered localized corrosion rates in susceptible alloys. Ennobling biofilms were composed of microbial cells, diatoms and extracellular polymeric substances and the bacterial community in biofilms was affected by both the alloy composition and seawater treatment.