Food-grade D-limonene enhanced a green biocide in the mitigation of carbon steel biocorrosion by a mixed-culture biofilm consortium.

Microbiologically influenced corrosion (MIC), or microbial biocorrosion, is caused directly by microbial metabolic activities/products or induced by microbial biofilm's damage of a protective film that exposes a solid surface to a pre-existing corrosive environment. MIC causes billions of dollars of losses in various industrial processes, especially in oil and gas and water utilities. The mitigation of problematic industrial microbes typically relies on biocides whose discharges can cause environmental problems. Thus, more effective biocide applications are desired to minimize environmental impact. D-Limonene, a citrus peel oil, generally regarded as safe (GRAS), was used to enhance the popular biodegradable tetrakis hydroxymethyl phosphonium sulfate (THPS) biocide. An oilfield mixed-culture biofilm was grown anaerobically in enriched artificial seawater containing C1018 carbon steel coupons for 7 days at 37 °C. One hundred ppm (w/w) D-limonene reduced general heterotrophic bacteria (GHB) and acid-producing bacteria (APB) effectively, leading to 5.4-log and 6.0-log reductions in sessile GHB and APB cell counts, respectively, compared to no treatment control. The combination of 100 ppm D-limonene + 100 ppm THPS achieved extra 1.0-log SRB, 0.6-log GHB and 0.5-log APB reductions in sessile cell counts, which led to extra 58% reduction in microbial corrosion mass loss (1.2 vs. 0.5 mg/cm2) and extra 30% reductions in maximum pit depth (11.5 vs. 8.1 µm), compared to 100 ppm THPS-only treatment. Linear polarization resistance and potentiodynamic polarization (PDP) corrosion data supported mass loss and pitting data. Mixed-culture biofilms on carbon steel coupons after 7 day incubation at 37 °C showing enhanced biocide treatment outcome using D-limonene + THPS: A no treatment, B 100 ppm D-limonene, C 100 ppm THPS, D 100 ppm D-limonene + 100 ppm THPS.

Efficacy of glutaraldehyde enhancement by D-limonene in the mitigation of biocorrosion of carbon steel by an oilfield biofilm consortium.

Microbiologically influenced corrosion (MIC) is one of the major corrosion threats in the oil and gas industry. It is caused by environmental biofilms. Glutaraldehyde is a popular green biocide for mitigating biofilms and MIC. This work investigated the efficacy of glutaraldehyde enhancement by food-grade green chemical D-limonene in the biofilm prevention and MIC mitigation using a mixed-culture oilfield biofilm consortium. After 7 days of incubation at 37 °C in enriched artificial seawater in 125 mL anaerobic vials, the 100 ppm (w/w) glutaraldehyde + 200 ppm D-limonene combination treatment reduced the sessile cell counts on C1018 carbon steel coupons by 2.1-log, 1.7-log, and 2.3-log for sulfate reducing bacteria, acid producing bacteria, and general heterotrophic bacteria, respectively in comparison with the untreated control. The treatment achieved 68% weight loss reduction and 78% pit depth reduction. The 100 ppm glutaraldehyde + 200 ppm D-limonene combination treatment was found more effective in biofilm prevention and MIC mitigation than glutaraldehyde and D-limonene used individually. Electrochemical tests corroborated weight loss and pit depth data trends.

Surface roughness influence on extracellular electron microbiologically influenced corrosion of C1018 carbon steel by Desulfovibrio ferrophilus IS5 biofilm.

Carbon steel microbiologically influenced corrosion (MIC) by sulfate reducing bacteria (SRB) is known to occur via extracellular electron transfer (EET). A higher biofilm sessile cell count leads to more electrons being harvested for sulfate reduction by SRB in energy production. Metal surface roughness can impact the severity of MIC by SRB because of varied biofilm attachment. C1018 carbon steel coupons (1.2 cm2 top working surface) polished to 36 grit (4.06 µm roughness which is relatively rough) and 600 grit (0.13 µm) were incubated in enriched artificial seawater inoculated with highly corrosive Desulfovibrio ferrophilus IS5 at 28 â„ƒ for 7 d and 30 d. It was found that after 7 d of SRB incubation, 36 grit coupons had a 11% higher sessile cell count at (2.0 ± 0.17) × 108 cells/cm2, 52% higher weight loss at 22.4 ± 5.9 mg/cm2 (1.48 ± 0.39 mm/a uniform corrosion rate), and 18% higher maximum pit depth at 53 µm compared with 600 grit coupons. However, after 30 d, the differences diminished. Electrochemical tests with transient information supported the weight loss data trends. This work suggests that a rougher surface facilitates initial biofilm establishment but provides no long-term advantage for increased biofilm growth.

Electrochemical Assessment of Mitigation of Desulfovibrio ferrophilus IS5 Corrosion against N80 Carbon Steel and 26Cr3Mo Steel Using a Green Biocide Enhanced by a Nature-Mimicking Biofilm-Dispersing Peptide.

MIC (microbiologically influenced corrosion) is problematic in many industries, especially in the oil and gas industry. In this work, N80 carbon steel for pipelines was tested with 26Cr3Mo chromium pipeline steel for comparison in SRB (sulfate-reducing bacterium) MIC mitigation using a THPS (tetrakis hydroxymethyl phosphonium sulfate)-based commercial biocide (Biotreat 5475 with 75-80% THPS by mass). Peptide A, a nature-mimicking synthetic cyclic peptide (cys-ser-val-pro-tyr-asp-tyr-asn-trp-tyr-ser-asn-trp-cys) with biofilm dispersal ability was used as a biocide enhancer. Metal coupons covered with 3-d old Desulfovibrio ferrophilus IS5 biofilms were immersed in different biocide solutions. After 1-h treatment, 200 ppm Biotreat 5475, 200 ppm Biotreat 5475 + 200 nM (360 ppb) Peptide A, and 400 ppm Biotreat 5475 achieved 0.5-log, 1.7-log and 1.9-log reductions in sessile cell count on N80, and 0.7-log, 1.7-log, and 1.8-log on 26Cr3Mo, respectively. The addition of 200 nM Peptide A cut the THPS biocide dosage by nearly half. Biocide injection tests in electrochemical glass cells after 1 h exhibited 15%, 70%, and 72% corrosion inhibition efficiency (based on corrosion current density) on N80, and 27%, 79%, 75% on 26Cr3Mo, respectively. Linear polarization resistance and electrochemical impedance spectrometry results also indicated antimicrobial efficacies.

Microbiologically influenced corrosion of titanium by Desulfovibrio vulgaris biofilm under organic carbon starvation.

Desulfovibrio vulgaris biofilm was pre-grown on Ti coupons for 7 d and then the biofilm covered coupons were incubated again with fresh culture media with 10 % (reduced) and 100 % (normal) carbon source levels, respectively. After the pre-growth, sessile D. vulgaris cell count reached 107 cells/cm2. The sessile cell counts were 2 × 107 and 4.2 × 107 cells/cm2 for 10 % and 100 % carbon sources, respectively after the subsequent 7 d starvation test. The maximum pit depth after the 7 d pre-growth was 4.7 µm. After the additional 7 d of the starvation test, the maximum pit depth increased to 5.1 µm for 100 % carbon source vs 6.2 µm for 10 % carbon source. Corrosion current density (icorr) from potentiodynamic polarization data at the end of the 7 d starvation test for 10 % carbon source was more than 3 times of that for 100 % carbon source, despite a reduced sessile cell count with 10 % carbon source. The polarization resistance (Rp) started to decrease within minutes after 20 ppm (w/w) riboflavin (electron mediator) injection. The carbon starvation data and riboflavin corrosion acceleration data both suggested that D. vulgaris utilized elemental Ti as an electron source to replace carbon source as the electron donor during carbon source starvation.

Mechanical property degradation of X80 pipeline steel due to microbiologically influenced corrosion caused by Desulfovibrio vulgaris.

Apart from pinhole leaks, MIC (microbiologically influenced corrosion) can also cause catastrophic failures such as pipe ruptures and support beam collapses due to mechanical property degradation or stress corrosion cracking. In this work, X80 pipeline steel dogbone coupons and square coupons were immersed in 150 ml broths containing Desulfovibrio vulgaris, a common corrosive sulfate reducing bacterium (SRB), for up to 14 days. The headspace volumes in the anaerobic bottles were increased from 150 ml to 200 ml and 300 ml to increase MIC severity. After 14 days of SRB incubation in ATCC 1249 culture medium with X80 coupons at 37°C, the sessile cell counts were 6.5 × 107 cells cm-2 for 150 ml, 2.3 × 108 cells cm-2 for 200 ml and 1.4 × 109 cells cm-2 for 300 ml headspace volumes, respectively owing to reduced H2S cytotoxicity in the broth with a larger headspace because it allowed more biogenic H2S to escape from the broth. Weight losses were 1.7 mg cm-2, 1.9 mg cm-2 and 2.3 mg cm-2 for 150 ml, 200 ml and 300 ml headspace volumes, respectively. The corresponding pit depths were 2.6 µm, 4.2 µm and 6.2 µm for 150 ml, 200 ml and 300 ml headspace volumes, respectively. Electrochemical impedance spectroscopy (EIS), linear polarization resistance (LPR) and potentiodynamic polarization results corroborated the increasing weight loss and pitting data trends as a result of increased headspace. Tensile testing of dogbone coupons after the 14-day SRB immersion test indicated that more severe MIC pitting led to a higher ultimate strain loss by up to 23% (300 ml headspace) compared to the abiotic control, while the ultimate strength losses for all headspace volumes were quite small (3% and lower).

Mitigation of carbon steel biocorrosion using a green biocide enhanced by a nature-mimicking anti-biofilm peptide in a flow loop.

Biocorrosion, also called microbiologically influenced corrosion (MIC), is a common operational threat to many industrial processes. It threatens carbon steel, stainless steel and many other metals. In the bioprocessing industry, reactor vessels in biomass processing and bioleaching are prone to MIC. MIC is caused by biofilms. The formation and morphology of biofilms can be impacted by fluid flow. Fluid velocity affects biocide distribution and MIC. Thus, assessing the efficacy of a biocide for the mitigation of MIC under flow condition is desired before a field trial. In this work, a benchtop closed flow loop bioreactor design was used to investigate the biocide mitigation of MIC of C1018 carbon steel at 25 °C for 7 days using enriched artificial seawater. An oilfield biofilm consortium was analyzed using metagenomics. The biofilm consortium was grown anaerobically in the flow loop which had a holding vessel for the culture medium and a chamber to hold C1018 carbon steel coupons. Peptide A (codename) was a chemically synthesized cyclic 14-mer (cys-ser-val-pro-tyr-asp-tyr-asn-trp-tyr-ser-asn-trp-cys) with its core 12-mer sequence originated from a biofilm dispersing protein secreted by a sea anemone which possesses a biofilm-free exterior. It was used as a biocide enhancer. The combination of 50 ppm (w/w) THPS (tetrakis hydroxymethyl phosphonium sulfate) biocide + 100 nM (180 ppb by mass) Peptide A resulted in extra 1-log reduction in the sulfate reducing bacteria (SRB) sessile cell count and the acid producing bacteria (APB) sessile cell count compared to 50 ppm THPS alone treatment. Furthermore, with the enhancement of 100 nM Peptide A, extra 44% reduction in weight loss and 36% abatement in corrosion pit depth were achieved compared to 50 ppm THPS alone treatment.

Aggressive corrosion of carbon steel by Desulfovibrio ferrophilus IS5 biofilm was further accelerated by riboflavin.

EET (extracellular electron transfer) is behind MIC (microbiologically influenced corrosion) of carbon steel by SRB (sulfate reducing bacteria). This work evaluated 20 ppm (w/w) riboflavin (an electron mediator) acceleration of C1018 carbon steel MIC by Desulfovibrio ferrophilus IS5 in enriched artificial seawater (EASW) after 7-d incubation in anaerobic vials at 28 °C. Twenty ppm riboflavin did not significantly change cell growth or alter the corrosion product varieties, but it led to 52% increase in weight loss and 105% increase in pit depth, compared to the control without 20 ppm riboflavin. With 20 ppm riboflavin supplement in EASW, D. ferrophilus yielded weight loss-based corrosion rate of 1.57 mm/y (61.8 mpy), and pit depth growth rate of 2.88 mm/y (113 mpy), highest reported for short-term pure-strain SRB MIC of carbon steel. Electrochemical tests in 450 mL glass cells indicated that the biofilm responded rather quickly to the riboflavin injection (20 ppm in broth) to the culture medium. Polarization resistance (Rp) began to decrease within minutes after injection. Within 2 h, the riboflavin injection led to 31% decrease in Rp and 35% decrease in Rct + Rf from electrochemical impedance spectroscopy (EIS). The Tafel corrosion current density increased 63% 2 h after the injection.