Mitigation of sulfate reducing Desulfovibrio ferrophilus microbiologically influenced corrosion of X80 using THPS biocide enhanced by Peptide A

Abstract

• Peptide A is a non-biocidal biofilm dispersal agent for biocide enhancement. • 20 ppm (w/w) THPS is insufficient to mitigate D. ferrophilus MIC of X80 steel. • 20 ppm THPS is enhanced by 100 ppb Peptide A, achieving 83% lower weight loss. • It also achieves 4-log extra sessile cell reduction compared with 20 ppm THPS. • 20 ppm THPS + 100 ppb Peptide A weight loss is similar to that for 50 ppm THPS. Tetrakis hydroxymethyl phosphonium sulfate (THPS) was enhanced by a 14-mer Peptide A, with its core 12-mer sequence mimicking part of Equinatoxin II protein, in the mitigation of sulfate reducing Desulfovibrio ferrophilus MIC (microbiologically influenced corrosion) of X80 carbon steel. Results proved that 50 ppm (w/w) THPS was sufficient to mitigate the D. ferrophilus biofilm, and its very agressive MIC (19.7 mg/cm 2 in 7 days or 1.31 mm/a), but not 20 ppm THPS. To achieve effective mitigation at a low dosage of THPS, biofilm-dispersing Peptide A was added to 20 ppm THPS in the culture medium. Sessile cell counts were reduced by 2-log and 4-log after enhancement by 10 ppb and 100 ppb Peptide A, respectively. Enhancement efficiency (further reduction in corrosion rate) reached 69% for 10 ppb Peptide A and 83% for 100 ppb Peptide A compared with 20 ppm THPS alone treatment, indicating that Peptide A was a good biocide enhancer for THPS.