Activity Of Sulfate-reducing Bacteria Research Articles

STUDY OF AMINOESTERS OF SYNTHETIC PETROLEUM ACID PRODUCED BY AEROBIC OXIDATION OF NAPHTHEN-PARAFFIN HYDROCARBONS, AS CORROSION INHIBITORS

This article presents the results of research in the field of synthesis of amino esters obtained on the basis of mono, di, triethanolamine and synthetic petroleum acid in a molar ratio of 1:1.The structure and structure of the obtained substances were confirmed by IR spectroscopy. The inhibitor-bactericidal effect of amino esterson the corrosion process has been studied. The inhibitory effect of the synthesized amino esters on CO2 steel corrosion at concentrations of 25, 50, and 100 mg/L was studied. Samples T-1, T-2, T-3 at a concentration of 25 mg/l for 20 hours showed an inhibitory effect of 40,36…74,15%, respectively, at a concentration of 50 mg/l, respectively 79,96…92,04 %, at a concentration of 100 mg/l, respectively, 98,09…99,59%. In order to study the antimicrobial activity of the obtained amino esters, their solutions were prepared in various media (isopropyl alcohol 60%) at five different concentrations (5; 50; 500; 600; 700 mg/l) and their effect on the vital activity of sulfate-reducing bacteria (SRB) was studied at 30…32 °C for 15 days. It has been established that at a concentration of 600 mg/l, the synthesized amino esters exhibit a 95,2…100% bactericidal effect, and at a concentration of 700 mg/l, they exhibit a 100% bactericidal effect, completely suppressing the vital activity of bacteria. The synthesized complexes exhibit a higher bactericidal effect even at low concentrations. Thus, the bactericidal and CO2-corrosion-inhibiting properties of amino esters synthesized on the basis of synthetic petroleum acid obtained in the process of aerobic oxidation of paraffin-naphthenic hydrocarbons isolated from the diesel fraction (boiling range 190…330 °C) in the presence of transition-metal-modified nanosized γ-Al2O3 catalyst, and ethanolamines.

Mechanistic insights into CO2 pressure regulating microbial competition in a hydrogen-based membrane biofilm reactor for denitrification.

CO2 is a proven pH regulator in hydrogen-based membrane biofilm reactor (H2-MBfR) but how its pressure regulates microbial competition in this system remains unclear. This work evaluates the CO2 pressure dependent system performance, CO2 allocation, microbial structure and activity of CO2 source H2-MBfR. The optimum system performance was reached at the CO2 pressure of 0.008MPa, and this pressure enabled 0.18gC/(m2·d) of dissolved inorganic carbon (DIC) allocated to denitrifying bacteria (DNB) for carbon source anabolism and denitrification-related proton compensation, while inducing a bulk liquid pH (pH 7.4) in favor of DNB activity by remaining 0.21gC/(m2·d) of DIC as pH buffer. Increasing CO2 pressure from 0.008 to 0.016MPa caused the markedly changed DNB composition, and the diminished DNB population was accompanied by the enrichment of sulfate-reducing bacteria (SRB). A high CO2 pressure of 0.016MPa was estimated to induce the enhanced SRB activity and weakened DNB activity.

3D modelling of long-term sulfide corrosion of copper canisters in a spent nuclear fuel repository

Copper canisters are a central component in the safety of the Finnish spent fuel repository concept (KBS-3), where the main corrodent potentially affecting the canister integrity is sulfide. In this study, a 3D numerical model is developed to assess the evolution of sulfide fluxes and the spatially resolved canister corrosion depths for the Finnish spent nuclear fuel repository concept. The backfilled tunnel and the disposal hole are implemented using repository geometries, with sulfide being produced at their interface with the rock (excavation damaged zone) by sulfate reducing bacteria (SRB). Recent experimental findings regarding the microbial sulfate reduction process as well as the scavenging of sulfide via iron (oxy)hydroxides are incorporated in the reactive transport model. Long-term simulations are performed, predicting a heterogeneous corrosion of the canister with a max. corrosion depth of 1.3 mm at the bottom corner after one million years. The evolution of sulfide fluxes shows two main phases, depending on the source of sulfate: first sulfate is supplied by the dissolution of gypsum from the bentonite barriers, followed by a steady, low-level supply from the groundwater. Sensitivity cases demonstrate that both the organic carbon and Fe(III) oxide contents in the bentonite are critical to the corrosion evolution, by being the main electron donor for SRB activities and the major sulfide scavenger in the bentonite, respectively. The backfilled tunnel contributes little to the flux of corrosive sulfide to the canister due to the attenuation by Fe(III)-oxides/hydroxides but induces a notable flux of sulfate into the disposal hole.

Glycerol amendment enhances biosulfidogenesis in acid mine drainage-affected areas: An incubation column experiment.

Microbial sulfate (SO4 2−) reduction in Acid Mine Drainage (AMD) environments can ameliorate the acidity and extreme metal concentrations by consumption of protons via the reduction of SO4 2− to hydrogen sulfide (H2S) and the concomitant precipitation of metals as metal sulfides. The activity of sulfate-reducing bacteria can be stimulated by the amendment of suitable organic carbon sources in these generally oligotrophic environments. Here, we used incubation columns (IC) as model systems to investigate the effect of glycerol amendment on the microbial community composition and its effect on the geochemistry of sediment and waters in AMD environments. The ICs were built with natural water and sediments from four distinct AMD-affected sites with different nutrient regimes: the oligotrophic Filón Centro and Guadiana acidic pit lakes, the Tintillo river (Huelva, Spain) and the eutrophic Brunita pit lake (Murcia, Spain). Physicochemical parameters were monitored during 18 months, and the microbial community composition was determined at the end of incubation through 16S rRNA gene amplicon sequencing. SEM-EDX analysis of sediments and suspended particulate matter was performed to investigate the microbially-induced mineral (neo)formation. Glycerol amendment strongly triggered biosulfidogenesis in all ICs, with pH increase and metal sulfide formation, but the effect was much more pronounced in the ICs from oligotrophic systems. Analysis of the microbial community composition at the end of the incubations showed that the SRB Desulfosporosinus was among the dominant taxa observed in all sulfidogenic columns, whereas the SRB Desulfurispora, Desulfovibrio and Acididesulfobacillus appeared to be more site-specific. Formation of Fe3+ and Al3+ (oxy)hydroxysulfates was observed during the initial phase of incubation together with increasing pH while formation of metal sulfides (predominantly, Zn, Fe and Cu sulfides) was observed after 1–5 months of incubation. Chemical analysis of the aqueous phase at the end of incubation showed almost complete removal of dissolved metals (Cu, Zn, Cd) in the amended ICs, while Fe and SO4 2− increased towards the water-sediment interface, likely as a result of the reductive dissolution of Fe(III) minerals enhanced by Fe-reducing bacteria. The combined geochemical and microbiological analyses further establish the link between biosulfidogenesis and natural attenuation through metal sulfide formation and proton consumption.

Arsenic and cadmium bioavailability to rice (Oryza sativa L.) plant in paddy soil: Influence of sulfate application

Arsenic (As) and cadmium (Cd) accumulate easily in rice grains that pose a non-negligible threat to human health worldwide. Sulfur fertilizer has been shown to affect the mobilization of As and Cd in paddy soil, but the effect of co-contamination by As and Cd has not been explored. This study selected three soils co-contaminated with As and Cd from Shangyu (SY), Tongling (TL) and Ma'anshan (MA). Incubation experiments and pot experiments were carried out to explore the effect of sulfate supply (100 mg kg−1) on the bioavailability of As and Cd in soil and the rice growth. The results showed that the exogenous sulfate decreased As concentrations in porewater of SY and TL by 51.1% and 29.2% through forming arsenic-sulfide minerals. The exchangeable Cd in soil also declined by 25.6% and 18.6% and transformed into Fe and Mn oxides-bound Cd. The relative abundance of Desulfotomaculum, Desulfurispora and dsr gene increased remarkably indicated that sulfate addition stimulated the activity of sulfate-reducing bacteria. In MA soil, sulfate addition immobilized Cd but had little effect on As solubility, which was speculated to be related to the high sulfate background of the soil. Further pot experiments showed that sulfate application significantly increased rice tillers, biomass, chlorophyll content in shoots, and decreased electrolyte leakage in root. Finally, sulfate significantly reduced As and Cd in SY rice shoots by 60.2% and 40.8%, respectively, while As decreased by 39.6% in TL rice shoots and Cd decreased by 23.0% in MA rice shoots. These results indicate that the application of sulfate can reduce the bioavailability of As and Cd in the soil-rice system and promote rice growth, and it is possible to reduce the accumulation of As and Cd in rice plants simultaneously.

Assessing Alternative Supporting Organic Materials for the Enhancement of Water Reuse in Subsurface Constructed Wetlands Receiving Acid Mine Drainage

Acid mine drainage (AMD) is a global problem with severe consequences for the environment. South Africa’s abandoned mines are a legacy from the country’s economic dependence on the mining sector, with consequent negative impacts on ecosystems. AMD remediation includes active and passive techniques. Constructed wetlands (a passive technique) have lower operational costs but require larger spaces and longer timeframes to achieve the remediation of AMD, and are supported by anaerobic sulphate-reducing bacteria (SRB), which capable of remediating high-sulphate-laden AMD while precipitating dissolved metals from the AMD. Organic substrates supporting these activities are often the limiting factor. When enhancing existing passive AMD remediation technologies, alternative waste material research that may support SRB activity is required to support the circular economy through the reduction in waste products. Chicken feathers show potential as a substrate enhancer, boosting organic carbon availability to SRB, which sustains passive AMD treatment processes by achieving pH elevation, sulphate and metal reductions in AMD water for reuse. Microbial biodiversity is essential to ensure the longevity of passive treatment systems, and chicken feathers are proven to have an association with SRB microbial taxa. However, the longer-term associations between the AMD water parameters, microbial diversity and the selected substrates remain to be further investigated.

SYNTHESIS OF AMINOMETHOXY DERIVATIVES OF CYCLOHEXANOL AND STUDYING THEM AS BACTERICIDE INHIBITORS

Based on cyclohexanol, cyclic amines (piperidine, morpholine, hexamethyleneimine), and formaldehyde, new Mannich bases have been synthesized. The reaction was carried out at a temperature of 78–800C for 4–5 h in a benzene solution at an equimolar ratio of the starting components. The yield of compounds was 69–75%. The physicochemical data of the synthesized compounds were determined. The composition and structure of the target products were confirmed by elemental analysis, IR, 1H and 13C NMR spectroscopy, and mass spectrometry. Their effect on the vital activity of sulfate-reducing bacteria of the "Desulfovibrio desulfuricans" type at three concentrations (25; 50; 100 mg/l) was studied. The obtained compounds showed high bactericidal properties, 1% solutions of these compounds in isopropyl alcohol at a concentration of 100 mg/l showed 100% bactericidal effect. A 1% solution of the compound with a fragment of morpholine already at a concentration of 50 mg/l exhibits a 100% bactericidal effect. Compounds with a fragment of piperidine and hexamethyleneimine at a concentration of 50 mg/l showed 96.2 and 98% bactericidal effects, respectively. And at a concentration of 25 mg/l, the bactericidal effect of all three compounds was 16.4%, 36.4%, and 58.2%, respectively. The results obtained show that the synthesized compounds showed more bactericidal properties compared to the industrially used bactericide-inhibitors АМДОР ИК-7 and АМДОР ИК-10 taken as a standard. Established, that these aminomethoxy derivatives of cyclohexanol affect bacteria at very low concentrations, they can be proposed as effective inhibitors against sulfate-reducing bacteria

Inhibition of Sulfate Reduction and Cell Division by Desulfovibrio desulfuricans Coated in Palladium Metal.

The growth of sulfate-reducing bacteria (SRB) and associated hydrogen sulfide production can be problematic in a range of industries such that inhibition strategies are needed. A range of SRB can reduce metal ions, a strategy that has been utilized for bioremediation, metal recovery, and synthesis of precious metal catalysts. In some instances, the metal remains bound to the cell surface, and the impact of this coating on bacterial cell division and metabolism has not previously been reported. In this study, Desulfovibrio desulfuricans cells (1g dry weight) enabled the reduction of up to 1500 mmol (157.5 g) palladium (Pd) ions, resulting in cells being coated in approximately 1 μm of metal. Thickly coated cells were no longer able to metabolize or divide, ultimately leading to the death of the population. Increasing Pd coating led to prolonged inhibition of sulfate reduction, which ceased completely after cells had been coated with 1200 mmol Pd g-1 dry cells. Less Pd nanoparticle coating permitted cells to carry out sulfate reduction and divide, allowing the population to recover over time as surface-associated Pd diminished. Overcoming inhibition in this way was more rapid using lactate as the electron donor, compared to formate. When using formate as an electron donor, preferential Pd(II) reduction took place in the presence of 100 mM sulfate. The inhibition of important metabolic pathways using a biologically enabled casing in metal highlights a new mechanism for the development of microbial control strategies. IMPORTANCE Microbial reduction of sulfate to hydrogen sulfide is highly undesirable in several industrial settings. Some sulfate-reducing bacteria are also able to transform metal ions in their environment into metal phases that remain attached to their outer cell surface. This study demonstrates the remarkable extent to which Desulfovibrio desulfuricans can be coated with locally generated metal nanoparticles, with individual cells carrying more than 100 times their mass of palladium metal. Moreover, it reveals the effect of metal coating on metabolism and replication for a wide range of metal loadings, with bacteria unable to reduce sulfate to sulfide beyond a specific threshold. These findings present a foundation for a novel means of modulating the activity of sulfate-reducing bacteria.

AMINOMETHOXY DERIVATIVES OF CYCLOHEXANOL AS BIOCORROSION INHIBITORS

Based on cyclohexanol, aliphatic amines (diethylamine, dipropylamine, dibutylamine, dihexylamine), and formaldehyde, new Mannich bases have been synthesized. The reaction was carried out at a temperature of 78–80°C for 4–5 h in a benzene solution at an equimolar ratio of the starting components. The yield of compounds was 63–80%. The physicochemical data of the synthesized compounds were determined. The composition and structure of the target products were confirmed by elemental analysis, IR, 1H and 13C NMR spectroscopy. Their influence on the vital activity of sulfate-reducing bacteria (SRB) of the "Desulfovibrio desulfuricans" type at three concentrations (25; 50; 100 mg/l) was studied. The resulting compounds showed high bactericidal properties. 1% solutions of these compounds in isopropyl alcohol at a concentration of 100 mg/l showed a 100% bactericidal effect. Given that these aminomethoxy derivatives of cyclohexanol affect bacteria at very low concentrations, they can be proposed as effective inhibitors against sulfate reducing bacteria. Keywords: cyclohexanol, aliphatic amines, Mannich bases, sulfatereducing bacteria, inhibitor-bactericides, biocorrosion.

Dynamic experiments of acid mine drainage with Rhodopseudomonas spheroides activated lignite immobilized sulfate-reducing bacteria particles treatment

Aiming at the problem that the treatment of acid mine drainage (AMD) by sulfate-reducing bacteria (SRB) biological method is susceptible to pH, metal ions, sulfate and carbon source. Lignite immobilized SRB particles (SRB-LP) and Rhodopseudomonas spheroides (R. spheroides) activated lignite immobilized SRB particles (R-SRB-LP) were prepared using microbial immobilization technology with SRB, R. spheroides and lignite as the main substrates. The dynamic experimental columns 1# and 2# were constructed with SRB-LP and R-SRB-LP as fillers, respectively, to investigate the dynamic repair effect of SRB-LP and R-SRB-LP on AMD. The mechanism of AMD treated with R-L-SRB particles was analyzed by scanning electron microscopy (SEM), fourier transform infrared (FTIR) spectrometer and low-temperature nitrogen adsorption. The result showed that the combination of R. spheroides and lignite could continuously provide carbon source for SRB, so that the highest removal rates of SO42−, Cu2+ and Zn2+ in AMD by R-SRB-LP were 93.97%, 98.52% and 94.42%, respectively, and the highest pH value was 7.60. The dynamic repair effect of R-SRB-LP on AMD was significantly better than that of SRB-LP. The characterization results indicated that after R-SRB-LP reaction, the functional groups of −OH and large benzene ring structure in lignite were broken, the lignite structure was destroyed, and the specific surface area was 1.58 times larger than before reaction. It illustrated that R. spheroides provided carbon source for SRB by degrading lignite. The strong SRB activity in R-SRB-LP, SRB can co-treat AMD with lignite, so that the dynamic treatment effect of R-SRB-LP on AMD is significantly better than that of SRB-LP.

Improved sulfate reduction efficiency of sulfate-reducing bacteria in sulfate-rich systems by acclimatization and multiple-grouting

The acclimation of sulfate-reducing bacteria (SRB) was performed to improve its adaptation in sulfate-rich systems with high sodium sulfate as a solution for disposing of soil salinization. The effects of pH, temperature, and carbon–sulfur ratio (CSR) on the activity and reduction efficiency (RE) of SRB were analyzed, and the influence of grouting times (GTs) on RE was studied. The impact of different sulfate-rich systems (i.e., sulfate-rich solution and soil) with different salinity on the RE of SRB was investigated. Results show that the optimum temperature and pH for the best activity and RE of SRB were 30°C and 7.0, respectively. The multiple acclimations for SRB significantly improved the activity and RE of SRB at high CSR. The RE of SRB decreased with increasing salinity since high salinity could inhibit SRB activity. The maximum RE of SRB-200 in sulfate-rich soils with 2% salinity is 40%, which may be due to the significant salinity tolerance degree of SRB-200, which is higher than SRB-150 and SRB-175. In addition, the RE of SRB in sodium sulfate solution was higher than that in sulfate-rich soil due to the soil having a complex skeletal structure. The RE of SRB significantly increased after low GTs (<5) and then remained constant after high GTs (>5). The optimal GTs obtained by SRB-150, SRB-175 and SRB-200 were 4, 4 and 5, respectively, corresponding to the final cumulative REs of 37.2%, 45.2% and 55.2%, respectively. The SEM results shows the formation of sulfides verified the reliability of SRB reduction in sulfate-rich systems. All results provide an important reference for the effective utilization of SRB in sulfate-rich systems.

SYNTHESIS OF ALKYLAMINE COMPLEXES BASED ON MALEIC ACIDS AND INVESTIGATION OF BACTERICIDAL PROPERTIES

This article presents the results of research in the field of synthesis of organic complexes based on propyl, butyl, pentyl and hexylamine and maleic acid in a molar ratio of 1:1. The structure and structure of the obtained substances were confirmed by IR and 1H NMR spectroscopy. Some physicochemical properties of the synthesized complex have been determined. In order to study the antimicrobial activity of the complexes obtained, their solutions were prepared in various media (water, isopropyl alcohol and ethyl alcohol) at three different concentrations (2.5; 5; 25 mg/l) and their effect on the vital activity of sulfate-reducing bacteria was studied at a temperature of 30... 32 °C for 15 days. It has been established that at a concentration of 2.5 mg/l, the synthesized complex salts exhibit a 96…98% bactericidal effect, and at a concentration of 5…25 mg/l, they exhibit a 100% bactericidal effect, completely suppressing the vital activity of bacteria. The synthesized complexes exhibit a higher bactericidal effect even at low concentrations. Thus, the preparation of organic complexes based on amines and maleic acid, as well as special-purpose inhibitors, components and composite materials based on them, is a very urgent problem. A number of studies have been carried out in this direction.

Cooperative microbial interactions mediate community biogeochemical responses to saltwater intrusion in wetland soils.

In freshwater wetlands, competitive and cooperative interactions between respiratory, fermentative and methanogenic microbes mediate the decomposition of organic matter. These interactions may be disrupted by saltwater intrusion disturbances that enhance the activity of sulfate-reducing bacteria (SRB), intensifying their competition with syntrophic bacteria and methanogens for electron donors. We simulated saltwater intrusion into wetland soil microcosms and examined biogeochemical and microbial responses, employing metabolic inhibitors to isolate the activity of various microbial functional groups. Sulfate additions increased total carbon dioxide production but decreased methane production. Butyrate degradation assays showed continued (but lower) levels of syntrophic metabolism despite strong demand by SRB for this key intermediate decomposition product and a shift in the methanogen community toward acetoclastic members. One month after removing SRB competition, total methane production recovered by only ∼50%. Similarly, butyrate assays showed an altered accumulation of products (including less methane), although overall rates of syntrophic butyrate breakdown largely recovered. These effects illustrate that changes in carbon mineralization following saltwater intrusion are driven by more than the oft-cited competition between SRB and methanogens for shared electron donors. Thus, the impacts of disturbances on wetland biogeochemistry are likely to persist until cooperative and competitive microbial metabolic interactions can recover fully.

Recovery of anaerobic system treating sulfate-rich wastewater using zero-valent iron

The anaerobic digestion (AD) process often fails in treating wastewater containing high levels of sulfate because sulfate-reducing bacteria (SRB) can reduce sulfate to sulfide and compete with methane-producing archaea (MPA) for their common substrates. The sulfide produced from the sulfate reduction could inhibit both MPA and SRB. In this study, we investigated the application of zero-valent iron (ZVI) to recover the growth and activities of MPA and SRB in an AD process treating wastewater with a relatively low ratio of chemical oxygen demand (COD) to sulfate ratio (SO42-) (9,000 mg COD/L glucose and 4,500 mg/L SO42-). The one-time addition of 210 g ZVI increased the CH4 production rates from near zero to 0.54 ± 0.15 L/L·d. An electron flow analysis (in terms of COD) demonstrated that the CH4-COD was approximately eight times higher than the COD contributed by ZVI electrons. The results indicated that ZVI not only provided extra electrons for use in hydrogenotrophic methanogenesis, but also provided ferrous ions that could co-precipitate with sulfides and reduced the inhibition of acetoclastic methanogens from undissociated H2S. ZVI helped recover the acetoclastic activity of the biomass to approximately the same level as the activity of the inoculum before being inhibited by sulfides and improved the hydrogenotrophic activity by over 72 times. In addition, ZVI had different effects on the acetoclastic activities of the culture attached to ZVI and the suspended culture. The acetoclastic activity of the culture attached to ZVI (0.446 ± 0.003 g COD/g COD·d) was only approximately half of that of the suspended culture (1.056 ± 0.070 g COD/g COD·d).

Authigenic Minerals of the Derbent and South Caspian Basins (Caspian Sea): Features of Forms, Distribution and Genesis under Conditions of Hydrogen Sulfide Contamination

This paper presents the results of complex lithological, mineralogical, and geochemical studies of bottom sediments of deep-water basins of the Caspian Sea (Derbent and South Caspian Basins) in areas contaminated by hydrogen sulfide. In the course of complex studies, numerous manifestations of authigenic mineral formation associated with the stage of early diagenesis have been established. Authigenic minerals belonging to the groups of sulfates (gypsum, barite), chlorides (halite), carbonates (calcite, low Mg-calcite; kutnohorite), and sulfides (framboidal pyrite), as well as their forms and composition, have been identified by a complex of analytical methods (X-ray diffractometry (XRD), scanning electron microscopy (SEM) with energy-dispersive X-ray spectroscopy (EDS); atomic absorption spectroscopy (AAS); coulometric titration (CT)); the nature of their distribution in bottom sediments has been assessed. Carbonates and sulfates are predominant authigenic minerals in the deep-water basins of the Caspian Sea. As a part of the study, differences have been established in the composition and distribution of associations of authigenic minerals in the bottom sediments in the deep-water basins. These are mineral associations characteristic of the uppermost part of the sediments (interval 0–3 cm) and underlying sediments. In the Derbent Basin, in sediments of the interval 3–46 cm, an authigenic association is formed from gypsum, calcite, magnesian calcite, siderite, and framboidal pyrite. An association of such authigenic minerals as gypsum and calcite is formed in sediments of the 0–3 cm interval. In the South Caspian Basin, in sediments of the interval 3–35 cm, an association of such authigenic minerals as gypsum, halite, calcite, magnesian calcite, and framboidal pyrite is formed. The association of such authigenic minerals as gypsum, halite, calcite, magnesian calcite, kutnohorite, and framboidal pyrite is characteristic of sediments of the 0–3 cm interval. We consider the aridity of the climate in the South Caspian region to be the main factor that determines the appearance of such differences in the uppermost layer of sediments of the basins. Judging by the change in the composition of authigenic associations, the aridity of the South Caspian increased sharply by the time of the accumulation of the upper layer of sediments (interval 0–3 cm). Taking into account lithological, mineralogical and geochemical data, the features of the processes of authigenic mineral formation in the deep-water basins of the Caspian Sea under conditions of hydrogen sulfide contamination have been determined. Analysis of the results obtained and published data on the conditions of sedimentation in the Caspian Sea showed that hydrogen sulfide contamination recorded in the bottom layer of the water column of the deep-water basins of the Caspian Sea may affect the formation of authigenic sulfides (framboidal pyrite), sulfates (gypsum), and carbonates (calcite and kutnohorite) associated with the activity of sulfate-reducing bacteria in reducing conditions.

Корозія бетону надводної частини нафтопастки в водному господарстві нафтовидобувного підприємства

The purpose of the work is to identify the type and kinetic indicators of concrete corrosion of the surface part of the oil trap in the water management of oil-and-gas facilities. Biogenic sulfuric acid concrete corrosion is a constant risk for water management facilities, in which hydrogen sulfide and its derivatives are present in the operating environment. Based on the analysis of the cycle of the oil production enterprise, the above processes are inherent in the water management of oil-and-gas facilities. The presence of hydrogen sulfide in water operating environments indicates a very high probability of the development of biogenic sulfuric acid aggression in the above-water moistened part of the structure - the influence of sulfuric acid produced by thion bacteria. An attractive environment for the accumulation of hydrogen sulfide by microbiological sulfate reduction is reservoir water at oil production sites, especially at water management sites where long-term sedimentation occurs. About 80% of losses from corrosion of oil industry equipment are associated with the activity of sulfate-reducing bacteria. In the experimental studies, concrete samples were studied, which were taken from the upper surface of the oil traps at the studied oil production facility located in the Dnipro-Donetsk depression. The results of a chemical study of concrete samples (decrease in pH, accumulation of sulfur compounds, and leaching of calcium compounds) indicated that the concrete is affected by biogenic sulfuric acid aggression. The experimentally determined dynamics of calcium compounds in the studied concrete samples indicated its leaching by aggressive sulfuric acid: the lower the pH of concrete, the lower the concentration of total calcium and the higher the concentration of mobile calcium. Based on data determined using a concrete corrosionmeter, the rate of microbiological corrosion of concrete was calculated - up to 0.08 mm/year, and the depth of diffusion of biogenic acids - up to 1.9 mm. The calculated average annual concentration of hydrogen sulfide in the atmosphere affecting concrete was 3.4 - 5.4 mg/m3, which exceeds the MPC of the working zone in the oil and gas industry.

Pengaruh Nitrat terhadap Biokorosi Logam oleh Konsorsium Bakteri Pereduksi Sulfat dari PLTA Saguling

&lt;div&gt;&lt;strong&gt;The Influence of Nitrate in Metal Biocorrosion caused by Sulfate Reducing Bacteria from Saguling Hydropower&lt;/strong&gt;. The corrosion facilitated and accelerated by the activities of microorganism is called biocorrosion. Sulfate reducing bacteria (SRB) is known as the bacteria that cause biocorrosion in anaerobic condition by using sulfate as the final electron acceptor. Biocorrosion reduces equipment lifetime and increases maintenance cost in industry. In the cooling system in Saguling hydropower, corrosion was commonly caused by utilization of contaminated water due to anorganic and organic waste, especially sulfate. In this research, sulfate reducing bacteria was isolated from biofilms in the cooling system of Saguling Hydropower. Molecular analysis using PCR-DGGE method with dsrB gene (350 bp) as molecular markers showed that SRB consortium contained 12 bands and assumed as different species of SRB. SRB consortium was tested to determine its biocorrosion activity over metal material of ST37 (carbon steel) and SUS304 (stainless steel). The consortium then treated with 7 different nitrate concentrations to determine its effect against the sulfate reducing bacteria activity. SRB consortium caused higher corrosion to ST37 than SUS304L, with the corrosion rate of 0.07660 mm/year and 0.00265 mm/year, respectively. Concentration of 10 mM nitrate effectively inhibited corrosion rate on ST37 and caused the changes in sulfate reducing bacteria communities, indicated by the disappearance of 6 bands in DGGE profile&lt;/div&gt;

Stimulation of dissimilatory sulfate reduction in response to sulfate in microcosm incubations from two contrasting temperate peatlands near Ithaca, NY, USA.

Peatlands are responsible for over half of wetland methane emissions, yet major uncertainties remain regarding carbon flow, especially when increased availability of electron acceptors stimulates competing physiologies. We used microcosm incubations to study the effects of sulfate on microorganisms in two temperate peatlands, one bog and one fen. Three different electron donor treatments were used (13C-acetate, 13C-formate and a mixture of 12C short-chain fatty acids) to elucidate the responses of sulfate-reducing bacteria (SRB) and methanogens to sulfate stimulation. Methane production was measured and metagenomic sequencing was performed, with only the heavy DNA fraction sequenced from treatments receiving 13C electron donors. Our data demonstrate stimulation of dissimilatory sulfate reduction in both sites, with contrasting community responses. In McLean Bog (MB), hydrogenotrophic Deltaproteobacteria and acetotrophic Peptococcaceae lineages of SRB were stimulated, as were lineages with unclassified dissimilatory sulfite reductases. In Michigan Hollow Fen (MHF), there was little stimulation of Peptococcaceae populations, and a small stimulation of Deltaproteobacteria SRB populations only in the presence of formate as electron donor. Sulfate stimulated an increase in relative abundance of reads for both oxidative and reductive sulfite reductases, suggesting stimulation of an internal sulfur cycle. Together, these data indicate a stimulation of SRB activity in response to sulfate in both sites, with a stronger growth response in MB than MHF. This study provides valuable insights into microbial community responses to sulfate in temperate peatlands and is an important first step to understanding how SRB and methanogens compete to regulate carbon flow in these systems.

The influence of carbon steel chemical composition on the biochemical activity of sessile sulfate-reducing bacteria

The technogenic failure caused by biological corrosion of pipelines and other oilfield equipment is an urgent problem for all oil-producing countries of the world. It has been established that many types of corrosion are initiated by the development of sulfate-reducing bacteria on the inner pipe surfaces. This paper presents the results of model laboratory experiments aimed at assessing the effect of the chemical composition of pipeline steel on the number and biochemical activity of sulfate-reducing bacteria development on its surface. Three chromium-containing corrosion-resistant steels were selected for the experiment, steel samples alloyed with 1% manganese were used as control samples. The bacteria for model experiments, mostly belonging to the genus Desulfovibrio, were taken from the inner surface of the damaged pipe after exploitation at an oil field in the Samara Region. In model experiments a reliable influence of the chemical composition of pipe steel on the quantitative characteristics and biochemical activity of bacteria developing on its surface was established. The biochemical activity of sulfate-reducing bacteria, determined by the stimulation of hydrogen sulfide formation and a change in dehydrogenase activity, significantly depended on the chromium content. An increase in the chromium concentration in the tested steel samples by up to 5% reduced the number of sulfate-reducing bacteria and their biochemical activity. The experiments allow us only to make a conclusion about the influence of the chemical composition of pipe steels on the number and biochemical activity of sulfate-reducing bacteria, but do not reveal its resistance to bacterial corrosion.

Insights into how poly aluminum chloride and poly ferric sulfate affect methane production from anaerobic digestion of waste activated sludge

Poly aluminum chloride (PAC) and poly ferric sulfate (PFS) are widely used in wastewater treatment and sludge dewatering, resulting in their amounts being accumulated substantially in waste activated sludge (WAS). Till now, however, little information about their influence on WAS digestion is available. This work therefore aims to provide insights into how PAC and PFS affect sludge anaerobic digestion. The experimental results showed that PFS's inhibition to methane production was much severer than PAC, in control reactor (0 mg Al or Fe /g TSS), the maximum cumulative methane production was 152.99 ± 7.18 mL/g VSS, when flocculants concentration increased to 30 mg Al/g TSS or 30 mg Fe/g TSS, the yields decreased to 129.54 ± 6.18 mL/g VSS and 89.52 ± 4.82 mL/g VSS respectively. Mechanism explorations exhibited that protein in WAS could bond with flocculants, which would inhibit protein bioconversion. It was also observed that the apparent activation energy (AAE) of organic solubilisation of PAC and PFS-contained sludge were increased by 38.58% and 18.67% respectively. Meanwhile, compared to the PFS, PAC led to more serious suppression of hydrolysis and acidogenesis processes, with propionic acid used as substrate, PFS inhibit methanogenesis more severely than PAC. Illumina MiSeq sequencing analyses showed that the number of sulfate-reducing bacteria (SRB) enriched obviously in PFS reactor. The results revealed that although PFS reduced methane production more severely than PAC, the reduction was mainly enforced by the activity of SRB but not organic enmeshment. Furthermore, PAC severely suppresses acetotrophic methanogens but PFS depress hydrogenotrophic methanogenesis microorganism mainly. Additionally, malodor control and dewaterability enhancement of digested sludge can be realized with PAC existence. The finding obtained in this study would provide insights into the PFS or PAC-involved sludge anaerobic digestion system and might support the important implication for further manipulate WAS treatment in the future.