Mitigating carbon steel corrosion in cooling water systems via bioaugmentation: Dynamic simulation and the modulation of sulfate reduction pathways

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Microbiologically influenced corrosion (MIC) compromises the sustainability of industrial water, driving the need for environmentally benign alternatives to traditional agents. This study evaluated a bioaugmentation strategy using a defined Bacillus consortium in a 100 L dynamic system replicating actual industrial hydrodynamics. The strategy achieved a 71.18% corrosion inhibition efficiency on Q235B carbon steel. Electrochemical measurements confirmed the formation of a protective organic-inorganic composite film, evidenced by a reduction in corrosion current density ( i corr ) from 48.9 to 7.71 μA cm −2 and a distinct increase in charge transfer resistance. The treatment also maintained circulating water quality. Ecologically, assembly analysis revealed that the consortium restructured the indigenous community via intensified deterministic selection. Consequently, corrosive taxa, such as sulfate-reducing bacteria (SRB) and iron-oxidizing bacteria (IOB), were competitively excluded, disrupting their synergistic corrosion cycle. Metagenomic and end-product analyses indicated the inhibition of corrosive dissimilatory sulfate reduction (DSR) and the enhancement of benign assimilatory sulfate reduction (ASR), evidenced by a 93.44% increase in cysteine and a 77.78% reduction in sulfide. Additionally, enriched urease and carbonic anhydrase genes, alongside increased enzymatic activities, facilitated biomineralization to fortify the protective composite matrix. These findings elucidate a targeted ecological regulation mechanism, offering a reliable foundation for scaling up industrial corrosion management.