Mineral accretion technology for end-of-life offshore platforms limits the development of corrosion-associated microbes supporting rig-to-reef conversion

Decommissioning practices of offshore oil and gas platforms at the end of their operational phase vary across countries and regions, depending on the legal framework, and generally require the complete removal of infrastructure. However, under specific circumstances, partial removal and conversion into artificial reefs may represent a more eco-sustainable option. In this case, the potential leaching of toxic compounds associated with corrosion of submerged metallic infrastructures, where microbially influenced corrosion (MIC) plays a major role, should be adequately considered. Since mineral accretion technology (i.e., the deposition of carbonates on metallic structures mediated by low-voltage electricity) offers a potential solution to prevent or mitigate corrosion, we assessed its effects on microbial biofilm development, its potential to reduce corrosion-associated microbes, and its capacity to create new substrates that support colonization by marine life. To this end, we used prototype electrified structures simulating the process as it could be applied to real end-of-life offshore platforms in the Mediterranean Sea. We investigated the microbial biofilm (both in terms of prokaryotic abundance and diversity), and its development over 9-month period on both electrified and non-electrified structures. Our results show that the biofilm on the electrified bars exhibited a higher microbial diversity, characterized by taxa generally encountered on carbonate substrates. Conversely, the biofilm on the non-electrified bars was dominated by taxa associated with MIC, which were nearly absent from the mineral-protected bars. These results suggest that mineral accretion technology has the potential to reduce the development of corrosion-associate microbes on end-of-life offshore platforms and to enhance substrate colonization by marine life. Overall, these findings support the potential implementation of rig-to-reef conversion. Rigs-to-reefs through mineral accretion technology. Comparison between prototypes of end-of-life offshore platforms with and without mineral accretion technology. Mineral-protected structures promote colonization of microbial taxa encountered on carbonate substrates and support sessile macrofauna growth. The structures without mineral accretion technology host microbial biofilm dominated by corrosion-associated microbes (e.g., sulfate-reducing, iron- and sulfur-oxidizing bacteria). • Mineral accretion technology limits the development of corrosion-associated microbes • Mineral-protected rigs host microbial taxa encountered on carbonate substrates • Mineral-protected rigs promote the colonization of sessile macro-organisms • Mineral accretion technology can be a sustainable tool for rig-to-reef conversion