Effect Of Sulfate-reducing Bacteria Research Articles

Synergistic effect of microorganisms and a direct current electric field on X70 steel corrosion in a near-neutral solution

In this paper, the corrosion behavior of X70 steel in the near-neutral simulated soil solution (NS4 solution) under the synergistic effect of sulfate reducing bacteria (SRB) and a direct current electric field (DCEF) were explored. The corrosion rate was determined with the electrochemical technique and the corrosion morphology and corrosion products were respectively characterized by SEM and XPS. In the sterile solution, corrosion morphology of X70 steel was pitting and the corrosion rate increased with the increase in DCEF intensity and exposure time. When DCEF was absent, the corrosion rate of X70 steel in bacterial NS4 solution was faster than that in the sterile solution and the corrosion morphology was general corrosion. The acceleration effect of DCEF on corrosion was more significant than that of SRB. Under the synergistic effect of SRB and DCEF, when DCEF intensity increased below 500 V/m, the metabolic activity of SRB was gradually enhanced and the corrosion rate of X70 steel decreased. The protective effect of biofilm weakened the acceleration effect of DCEF on corrosion and the corrosion behavior was controlled by SRB corrosion. When DCEF intensity increased above 1000 V/m, SRB cells were inactivated and the corrosion rate of X70 steel increased. The corrosion behavior of X70 steel was controlled by DCEF. Based on the above research results, preventative actions were proposed.

Effect of coexistence of sulfate reducing bacteria and nitrate reducing bacteria on the under-deposit corrosion of carbon steel

The effect of sulfate reducing bacteria (SRB) and nitrate reducing bacteria (NRB) on under-deposit corrosion (UDC) of carbon steel is studied by weight loss tests, electrochemical measurements and surface analysis. The results show that SRB-induced UDC is significantly inhibited by NRB. This inhibition is attributed to the accumulation of NRB in deposits suppressing the growth of SRB, as revealed by the analysis of total accumulation number of bacteria and the characterization of bacteria-formed micro-holes indicating localized accumulation of bacteria in deposits. The suppressed SRB growth in deposits is discussed based on the NRB-induced biologically competitive exclusion and metabolite inhibition mechanisms.

Effect of sulfate-reducing bacteria on stainless steel: a review

Effect of sulfate-reducing bacteria on stainless steel: a review

The influence of SRB on corrosion behavior of Cu-based medium-entropy alloy coating sprayed by HVOF

In this study, a novel Cu-based (Cu55Al20Ni12Ti8Si5, at.%) medium-entropy alloy (MEA) coating was prepared by high-velocity oxygen-fuel (HVOF) spraying technology. Thermo-Calc was employed to simulate the phase diagram of the alloy system. Phase composition and microstructure of the as-sprayed coating were characterized by means of XRD, FESEM, TEM and STEM/EDX. The effect of sulfate-reducing bacteria (SRB) on the corrosion behavior of the coating and the as-cast Ni-Al bronze (NAB) was investigated using electrochemical measurements and surface characterization. The Thermo-Cala simulation results showed that the alloy system presented a single BCC solid solution phase, while the detailed characterization of microstructure indicated that a few NiTi-rich B2-ordered precipitates could be also found in the as-sprayed coating other than the Cu-rich BCC matrix. Electrochemical studies illustrated that the coating exhibited superior corrosion resistance than the NAB in SRB medium, the corrosion acceleration efficiency induced by SRB of the NAB (95.3 %) was more severe than that of the coating (63.8 %). Surface analysis results demonstrated the occurrence of pitting corrosion and the formation of Cu2S on the coating surface after corroded in SRB medium. Corrosive metabolite HS- induced microbiologically influenced corrosion was considered as the main corrosion acceleration mechanism caused by SRB.

Corrosion of Q235 carbon steel induced by sulfate-reducing bacteria in groundwater: corrosion behavior, corrosion product, and microbial community structure.

Microbiologically influenced corrosion (MIC) is one of the reasons leading to the service failure of pipelines buried in the soil. In this work, the effect of sulfate-reducing bacteria (SRB) on the corrosion behavior of Q235 carbon steel in groundwater was investigated by electrochemical methods, surface analysis, and biological analysis. The results show that SRB utilizes iron as electron donor to sustain the vital activities of organic carbon-starved groundwater during the 14-day experimental period. The microbial community composition analysis at the genus level demonstrate that the diversity and richness decrease after corrosion, and the dominant SRB species has changed from Desulfovibrio to Desulfosporosinus. Moreover, the impedance of the carbon steel in the presence of biofilm was 1 order of magnitude higher than that of other periods in the electrochemical test, indicating that the biofilm and formed ferrous sulfide layer impeded the occurrence of corrosion. Although the 3D topography indicated that the surface of carbon steel was more uneven and pits were increased in the presence of SRB, the average weight loss (0.0396 ± 0.0050 g) was much higher than that without SRB (0.0139 ± 0.0007 g). These results implied that the growth of SRB makes the corrosion process of Q235 carbon steel more complicated.

Insight into sulfate-reducing bacteria corrosion behavior of X80 pipeline steel welded joint in a soil solution

The effect of sulfate-reducing bacteria (SRB) on the corrosion behavior of X80 steel welded joint in a soil solution was studied. The results indicated that SRB enhanced the corrosion of X80 steel welded joint. The corrosion behavior in the heat affected zone (HAZ) was quite different from those of in the weld metal (WM) and base metal (BM). The HAZ was an active region that could be preferentially and more quickly corroded. Macro-galvanic corrosion in the welded joint had a significant effect on the MIC behavior of the X80 steel welded joint, leading to the preferential corrosion of the HAZ.

Effect of sulfate reducing bacteria on the galvanic corrosion behavior of X52 carbon steel and 2205 stainless steel bimetallic couple

Effect of sulfate reducing bacteria (SRB) on the galvanic corrosion between 2205 SS (stainless steel) and X52 carbon steel in enriched artificial seawater (EASW) was comprehensively investigated, which was significant for understanding the microbiologically influenced corrosion of bimetallic composite pipelines. Electrochemical tests indicate that the galvanic effect in the SRB-containing medium was higher than that in the sterile medium. The coupling also promoted the corrosion of 2205 SS in biotic medium with a 13-fold increase in weight loss. The galvanic effect could increase the sessile cell density and accelerate the deterioration of the passive film of 2205 SS.

Effect of Sulfate-Reducing Bacteria on the Production of Iron Sulfides

Using Fourier transform infrared spectroscopy (FTIR) to identify the sulfate-reducing bacteria (SRB) in Daqing Oilfield sewage. The growth curve of SRB and the adsorption ability of extracellular polymeric substances (EPS) to the Fe2+ were combined to explore iron sulfide generation. X-ray diffraction (XRD) results showed that different species of SRB produce iron sulfides, mainly composed of mackinawite. The growth characteristics of SRB affected the formation of iron sulfides and had a negative charge. Various SRB growth trends were different. The growth of the bacterium in an exponential phase or log phase can be described by the greater concentration of inoculation. And smooth growth trends were contributed to the formation of FeS. At the same time, sulfur-rich, like FeS2, was easily formed when S2− (or S2 2−) played a major role compared with the protein and polysaccharide functional groups in the negatively charged EPS at the process of Fe2+ adsorption.

Influence of Sulfate Reduction on Arsenic Migration and Transformation in Groundwater Environment

The sulfate-reducing bacteria-mediated reduction process is considered to be an important mechanism affecting arsenic migration and transformation in anaerobic environments. To investigate the effect of sulfate-reducing bacteria in a high-arsenic aquifer on arsenic migration and transformation, the typical sulfate-reducing bacteria Desulfovibrio vulgaris was selected for micro-cosmic experiments to simulate a groundwater environment with or without sulfate amendment. The reduction of Fe(III) and As(V) by Desulfovibrio vulgaris was identified, and Fe(III) and As(V) were reduced in both sulfate-free and sulfate-containing systems. However, the addition of 1 mM sulfate significantly enhanced Fe(III) and As(V) reduction. Compared with no sulfate addition, 1 mM sulfate increased the reduction rates of Fe(III) and As(V) by 111.9% and 402.2%, respectively. The sulfate process mediated by Desulfovibrio vulgaris also remarkably promoted arsenic release in sediments. These results indicated that sulfate concentration should be considered when sulfate reduction is used as a remediation method for arsenic pollution in groundwater.

A comparative study of sulfate-reducing Desulfovibrio desulfuricans induced corrosion behaviors in Q235, X65, X70, and X80 pipeline steels

The effects of sulfate-reducing bacteria (SRB) on the corrosion behaviors of Q235, X65, X70 and X80 pipeline steels in the soil environment of Shenyang were evaluated. Both the results of weight loss and electrochemical measurements showed that the corrosion rates of these steels decreased in the order of X70 > Q235 > X65 > X80. The corrosion rate from weight loss of X70 steel was 1.2 times as much as that for X80 steel during the 14-day of immersion. Pitting corrosion was observed on the surfaces of these steels. The maximum pit depth of X70 steel was 12.9 μm, which was 3.4 times that of X80 steel. It was also found that the Stern-Geary constants (B values) of different steels in the MIC system has a certain difference, which is less than the generally recognized B value under the active corrosion state 26 mV.

Effect of SRB and Applied Potential on Stress Corrosion Behavior of X80 Steel in High-pH Soil Simulated Solution.

The effect of SRB and applied potential on the stress corrosion sensitivity of X80 pipeline steel was analyzed in high-pH soil simulated solution under different conditions using a slow strain rate tensile test, electrochemical test, and electronic microanalysis. The experimental results showed that X80 pipeline steel has a certain degree of SCC sensitivity in high-pH simulated solution, and the crack growth mode was trans-granular stress corrosion cracking. In a sterile environment, the SCC mechanism of X80 steel was a mixture mechanism of anode dissolution and hydrogen embrittlement at −850 mV potential, while X80 steel had the lowest SCC sensitivity due to the weak effect of AD and HE; after Sulfate Reducing Bacteria (SRB) were inoculated, the SCC mechanism of X80 steel was an AD–membrane rupture mechanism at −850 mV potential. The synergistic effect of Cl− and SRB formed an oxygen concentration cell and an acidification microenvironment in the pitting corrosion pit, and this promoted the formation of pitting corrosion which induced crack nucleation, thus significantly improving the SCC sensitivity of X80 steel. The strong cathodic polarization promoted the local corrosion caused by SRB metabolism in the presence of bacteria, whereby the SCC sensitivity in the presence of bacteria was higher than that in sterile conditions under strong cathodic potential.

Early corrosion behavior of X80 pipeline steel in a simulated soil solution containing Desulfovibrio desulfuricans

Microbiologically influenced corrosion (MIC) is one of the reasons leading to the service failure of pipelines buried in the soil. The effects of sulfate-reducing bacteria (SRB) on steel corrosion without organic carbon are not clear. In this work, SRB cells were enriched in the simulated soil solution, aiming to study SRB corrosion behavior without organic carbon source using weight loss, electrochemical measurements, and surface analysis. Effects of DO on SRB corrosion were also studied. Results indicate that SRB can survive after 14 days of incubation without organic carbon source, but approximately 90% SRB have died. SRB without organic carbon source could inhibit the uniform corrosion but enhance the pitting corrosion compared with the control specimen. The corrosion rate of the control calculated from weight loss is highest with a value of (0.081 ± 0.013) mm/y. The highest localized corrosion rate of (0.306 ± 0.006) mm/y is obtained with an initial SRB count of 107 cells/mL. The presence of DO influences the steel corrosion process. Oxygen corrosion dominates for the specimens in the absence and presence of SRB with an initial count of 103 cells/mL, while SRB MIC is primary for the specimens with high SRB counts.

Effect of Sulfate-Reducing Bacteria (SRB) on the Corrosion of Buried Pipe Steel in Acidic Soil Solution

The influence of sulfate-reducing bacteria (SRB) on the corrosion behaviors of X80 pipeline steel was investigated in a soil environment by electrochemical techniques and surface analysis. It was found that SRB grew well in the acidic soil environment and further attached to the coupon surface, resulting in microbiologically influenced corrosion (MIC) of the steel. The corrosion process of X80 steel was significantly affected by the SRB biofilm on the steel surface. Steel corrosion was inhibited by the highly bioactive SRB biofilm at the early stage of the experiment, while SRB can accelerate the corrosion of steel at the later stage of the experiment. The steel surface suffered severe pitting corrosion in the SRB-containing soil solution.

Effect of sulfate-reducing bacteria on hydrogen permeation and stress corrosion cracking behavior of 980 high-strength steel in seawater

980 high-strength steel has been widely used in marine engineering structures due to its high strength and toughness. However, it is easily affected by the harsh environmental conditions (such as the presence of sulfate-reducing bacteria, SRB), leading to the risk of stress corrosion cracking (SCC). In this paper, the effects of SRB and its metabolites on hydrogen permeation and SCC mechanism of 980 steel in seawater solution were investigated by slow strain rate tensile test, scanning electron microscope, X-ray energy spectroscopy, Raman spectroscopy and Devanathan-Stachurski double electrolytic cell. Results demonstrated that the SCC susceptibility of 980 steel was promoted in the presence of SRB, which was related to the cultivation time of the bacteria. When SRB were cultivated for 3 d and 6 d, the SCC mechanism was controlled by hydrogen-induced cracking (HIC); while the cultivation time extended to 11 d, the SCC of 980 steel was under the combined effect of the anodic dissolution (AD) and HIC mechanism. When cultivated for 16 d, the SCC of 980 steel was caused by the dominant AD. Both the SRB accelerated hydrogen permeation under cathodic depolarization process and SRB assisted AD (pitting corrosion) played an enhancing role in promoting SCC susceptibility of 980 steel.

Effect of sulfate reducing bacteria and stress on corrosion behavior of X100 steel in sea mud environment

The effects of different loading methods on the corrosion behavior of X100 steel in the sea mud environment were investigated. The results showed that the stress promoted the acceleration of the local dissolution of the metal surface and formed pitting. The poisoning effect of SRB prevents hydrogen atoms from combining into hydrogen molecules, promoting the penetration of hydrogen atoms into the metal, and increasing the probability of hydrogen embrittlement of the material. Therefore, in the simulated sea mud environment, the corrosion mechanism of X100 steel were affected by stress and SRB was based on anode dissolution, and there was the possibility of hydrogen embrittlement.

Effect of sulfate-reducing bacteria on corrosion of X80 pipeline steel under disbonded coating in a red soil solution

Effect of sulfate-reducing bacteria on the corrosion behaviors of API-X80 pipeline steel has been studied in crevices under simulated disbonded coatings in red soil solution. The results show that there are amounts of SRB in the crevice under the simulated disbonded coating in the red soil solution during the whole period of experiment. The electrochemical impedance spectroscopy shows that SRB can enhance the corrosion of the steel in the crevice under the simulated disbonded coating, and the thermodynamic analyses indicate that SRB can accelerate the corrosion of steel using not only sulfate but also ferric hydroxide as electron acceptors.

Simultaneous removal of nitrite and organics in a biofilm-enhanced high-salt wastewater treatment system via mixotrophic denitrification coupled with sulfate reduction

The reduction of sulfate to sulfide was seldom considered for high-salt wastewater treatment, although sulfide could supply electron donors to remove nitrite. The sulfate reduction, heterotrophic denitrification and autotrophic denitrification were integrated in one biofilm-enhanced high-salt wastewater treatment system and the sulfate reduction was used as an intermediate reaction. Both the reactor performances and the spatial distribution of the bacterial communities were studied. The metabolic pathways of carbon, nitrogen and sulfur were also discussed based on functional genes analysis. The removal efficiencies of nitrite and organics reached 100%, attributed to the stable and functional bacterial community. Desulfobacter, Sulfurimonas, Fastidiosipila and Pseudomonas were the dominant functional bacteria in the biofilm. The abundance and diversity of bacteria decreased with the increase of water depth because the different spatial concentrations of the substrates brought the various strength of each bio-reaction. Sulfate reduction was achieved through the assimilation pathway by various sulfate reduction genes. The oxidation of sulfide and reduction of nitrite were achieved through the autotrophic/heterotrophic denitrification pathways with functional genes. The seawater’s high salinity promoted the synergistic effect of sulfate reducing bacteria and desulfurization-denitrification bacteria, which helped the efficient operation of this biofilm-enhanced treatment system.

Microdefects of Biocorroded Pipe Steel Surfaces and Safety Assessment of Localized Stress Concentrators

The effect of sulfate-reducing bacteria (SRB) on the corrosion of steel 20 was investigated. Results demonstrated that the chemical composition of corrosion products, the corrosion rate, and corrosion type were altered due to the adherence of SRB and the subsequent formation of biofilm on the steel 20 surface. The micromechanisms of biocorrosion damage of specimens from pipe steel 20 were quantified on the basis of the microgeometry of the degraded surface and the localization parameters of corrosive stress microconcentrators. Stress concentrators in the vicinity of the micro-cuts, which are the depths of the profilograms, make it possible to evaluate safe (allowable) microcorrosion damage. The proposed approach complements the well-known methods for monitoring biodeterioration of pipe steels. With its help, it was found that a decrease in the corrosion rate of specimens with the addition of an inhibitor does not always clearly indicate its effectiveness. The case where the introduction of an inhibitor led to the destruction of the SRB biofilm on the surface of specimens from steel 20, but caused the activation of local corrosion processes and the formation of a more developed microrelief, is considered. The hollows of such microrelief are potential places of origin of defects, which require additional control.

Corrosion of 907 Steel Influenced by Sulfate-Reducing Bacteria

The effect of sulfate-reducing bacteria (SRB) on the corrosion of 907 steel was investigated. Results demonstrated that the chemical composition of corrosion products, the corrosion rate, and corrosion type were altered due to the adherence of SRB and the subsequent formation of biofilm on the 907 steel surface. Different from the case in sterile medium that ferrous oxides predominated in the corrosion products, ferrous sulfide was an important component in SRB-containing medium. Meanwhile, corrosion of 907 steel was enhanced by SRB, and the corrosion rate was dependent on their metabolic activity, which increased, stabilized, and decreased in the exponential growth, death, and residual phases, respectively. Furthermore, the corrosion type was changed from uniform corrosion to localized corrosion with the introduction of SRB, and the development process was analyzed based on the current distribution map of wire beam electrodes. In sterile medium, the maximum current density decreased with the immersion time extended, and there were no significant anodic current peaks in the late period, while in SRB-containing medium, the ratio between cathodic areas and anodic areas was high in the exponential growth phase, and stable anodic sites formed gradually in death and residual phases, which facilitated the development of localized corrosion.

Effect of Alternating Current and Sulfate-Reducing Bacteria on Corrosion of X80 Pipeline Steel in Soil-Extract Solution.

AC corrosion has been considere d as a threat to the corrosion of buried pipelines. Effects of sulfate-reducing bacteria (SRB) and alternating current (AC) on corrosion of X80 pipeline steel in soil-extract solution were investigated by electrochemical and surface analysis techniques. AC current can inhibit the growth of planktonic and sessile SRB. The corrosion current density of steel with 10 mA/cm2 AC current is about nine times bigger than that without AC current. Corrosion morphology changes from small pitting to large pitting holes with increasing AC current density. Corrosion of steel with SRB and AC current is controlled by both active dissolution of iron and film degradation.