Sulfate Reducing Bacterial Corrosion of Mild Steel in Liquid and Solid Media

Abstract

This study was carried out to check the corrosive impact of sulfate-reducing bacteria (SRB) on mild steel coupons in solid and liquid media under two variable nutritional conditions. The bacterial species for the experimental trials was isolated from buried corroded metallic installment and found motile, Gram- negative, non-spore former and identified by 16S rRNA gene sequencing as Desulfovibrio desulfuricans . The corrosive impact of SRB on steel coupons was performed in water as liquid medium and the processed clay as the solid medium without and with the provision of Postgate B medium. After 60 days of anaerobic incubation, corrosion rate (CR) and average percent weight loss (APWL) of the steel pieces were calculated. Higher CR and APWL were observed in the liquid medium (water) than in the solid medium (clay). The CR and APWL in water were 249 ± 2 µg dm −2 d −1 and 4.16 ± 0.25 %, respectively, while the corresponding figures for CR and APWL in clay were 108 ± 2 and 1.88 ± 0.29, respectively. In addition, the CR and APWL were higher in the presence of Postgate B medium compared to the medium without it. X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopic analyses reveals the presence of FeS in the corrosion product. Our findings of this study will be helpful for devising corrosion-protecting strategies.